@article{sadilek_huber_jang_barbosa_husain_2023, title={Analysis, Design, and Performance Evaluation of SiC Active Soft-Switching Cell for 1-ph3-ph Universal Voltage Input PFC for On-Board Charger Applications}, volume={38}, ISSN={["1941-0107"]}, DOI={10.1109/TPEL.2022.3199204}, abstractNote={In this article, a detailed analysis, design, and experimental evaluation of a continuous-conduction-mode, pulsewidth modulated, boost-type active soft-switching cell suitable for 1-ph/3-ph universal input voltage power factor correction (PFC) rectifier for on-board charging applications is introduced. The soft-switching cell features zero-voltage switching and simple control. The evaluation of the concept was performed on a 1-ph/3-ph combo 7.2-kW/12.5-kW prototype designed to operate at 230 V RMS 1–ph and 480 V RMS 3-ph line input and deliver 650–750 V output. At full load and 150 kHz switching frequency, the prototype achieves 98.8% efficiency in 3-ph operation and 98% efficiency in 1-ph interleaved operation. The soft-switching PFC concept naturally morphs between an interleaved totem-pole converter for 1-ph ac line voltage and a 3-ph converter for 3-ph ac line voltage.}, number={1}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Sadilek, Tomas and Huber, Laszlo and Jang, Yungtaek and Barbosa, Peter and Husain, Iqbal}, year={2023}, month={Jan}, pages={1204–1217} } @article{rachi_awal_husain_2023, title={Asymmetrical Fault Ride-Through and Power Oscillation Characterization for Grid-Tied Voltage Source Converters}, volume={59}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2023.3268280}, abstractNote={As the number of converter-interfaced distributed energy resources connected to the power system continues to increase rapidly, recent grid codes require these grid-tied converters to maintain grid connection during faults to ensure power supply security and reliability. In this work, we analyze the oscillation in the injected real and reactive power that a grid-tied voltage source converter (VSC) introduces as it attempts to contribute to the power quality and improve the voltage at the point of common coupling (PCC) during an asymmetrical fault. We propose a new double sequence current reference generation method that can be utilized to derive a closed-form quantification of the peak value of both the real and reactive power oscillation during asymmetrical fault ride-through (AFRT) analytically. The effect of the resulting bus voltage oscillation and ripple current requirement at twice the grid frequency, corresponding to the real power oscillation, on the input DC bus capacitor and upstream converter is analyzed for facilitating system component sizing. Furthermore, the proposed current reference generation formulation helps control the negative-sequence current injection during fault to assist with fault identification. The theoretical analysis is validated through simulation in PLECS for both asymmetrical and symmetrical fault scenarios. Experimental results for a three-phase, grid-tied VSC operating under both asymmetrical and symmetrical faults are provided to evaluate the performance of the proposed current reference generation method and validate the analysis presented}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Rachi, Md Rifat Kaisar and Awal, M. A. and Husain, Iqbal}, year={2023}, pages={4550–4561} } @article{awal_rachi_yu_husain_lukic_2023, title={Double Synchronous Unified Virtual Oscillator Control for Asymmetrical Fault Ride-Through in Grid-Forming Voltage Source Converters}, volume={38}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2022.3227729}, DOI={10.1109/TPEL.2022.3227729}, abstractNote={In this work, a double synchronous unified virtual oscillator controller is proposed for grid-forming voltage source converters to achieve synchronization to the fundamental frequency positive- and negative-sequence components of unbalanced grid voltage without any phase-locked loop. The proposed controller leverages a positive-sequence virtual oscillator and a negative-sequence virtual oscillator, a double-sequence current reference generator, and a double-sequence vector limiter. Under fault conditions, the controller enables to limit the converter output current below/at the maximum value allowable by the converter hardware while retaining synchronization regardless of the nature of grid faults. Consequently, symmetrical and asymmetrical fault ride-through can be achieved without the need for switching to a backup controller. This article presents the implementation and detailed analysis of the double-synchronous structure, which enables simultaneous synchronization to both sequences during current-unconstrained and -constrained operations. Validation of the proposed controller is provided through laboratory hardware experiments.}, number={6}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Awal, M. A. and Rachi, Md Rifat Kaisar and Yu, Hui and Husain, Iqbal and Lukic, Srdjan}, year={2023}, month={Jun}, pages={6759–6763} } @article{sadilek_huber_barbosa_husain_2023, title={Evaluation of Split-Phase Inverter Mode for 1-ph/3-ph Combo Soft-switching PFC for On-Board Charger Applications}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131600}, abstractNote={A detailed analysis and experimental evaluation of a split-phase inverter mode for 1-ph/3-ph universal voltage input electric vehicle (EV) on-board charger (OBC) is introduced. The power-factor-correcting (PFC) / inverter stage in the OBC is based on a simple continuous-conduction-mode (CCM), pulse-width-modulated (PWM), boost-type active soft-switching cell. The operating region of the split-phase inverter is investigated and experimentally verified. Due to soft-switching, the inverter achieves high efficiency, peaking at 98% at full load, at 150 kHz switching frequency.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Sadilek, Tomas and Huber, Laszlo and Barbosa, Peter and Husain, Iqbal}, year={2023}, pages={1888–1895} } @article{awal_rachi_yu_schroeder_dannehl_husain_2023, title={Grid-Forming Nature Retaining Fault Ride-Through Control}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131145}, abstractNote={A ride-through controller is proposed to enable inverter based resources (IBRs) to retain grid-forming (GFM) nature under current-constrained operation, such as faults or overload conditions. In this context, GFM nature for IBR is denoted by a voltage source behind reactance that preserves synchronism with the grid leveraging power-synchronization. A comparative analysis of existing GFM controllers is presented to demonstrate that the current state-of-the-art, either fails to preserve the GFM nature under fault, or offers only sub-optimal ride-through performance with regard to converter capacity uti-lization and transient stability. The proposed solution maximizes capacity utilization while retaining GFM nature under fault as well as enhances transient stability. Furthermore, detection of fault occurrence and/or clearance is not required and the identical control structure is preserved regardless of normal or fault/overload operation. Hence, the proposed controller avoids recurring fault-mode operation observed for existing GFM controllers at fault clearance especially under weak grid conditions. Experimental results are presented to validate the proposed solution.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Awal, M. A. and Rachi, Md Rifat Kaisar and Yu, Hui and Schroeder, Stefan and Dannehl, Jorg and Husain, Iqbal}, year={2023}, pages={2753–2758} } @article{sadilek_huber_barbosa_husain_2023, title={Investigation of Non-unity Power Factor Operation of 3-ph ZVS PFC Rectifier for On-Board Charging of Electric Vehicles}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131275}, abstractNote={In this paper, an analysis and experimental eval-uation of a non-unity power-factor operation of a 3-ph soft-switched on-board charger (OBC) for electric vehicles (EV) is introduced. With deeper penetration of distributed energy resources (DER), it is envisioned that OBC manufacturers will need to provide static compensation functionality to support the electric grid, which results in non-unity power factor operation. Soft-switching techniques generally constrain the operating region of a converter. In this research, it is shown that the soft-switching PFC rectifier can sustain operation power factor of 0.9 with discontinuous pulse-width modulation (PWM) scheme and power factor of 0.8 with sinusoidal PWM scheme due to the soft-switching cell capacitor voltage trajectory.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Sadilek, Tomas and Huber, Laszlo and Barbosa, Peter and Husain, Iqbal}, year={2023}, pages={1928–1935} } @article{awal_montes_teng_wang_bipu_yu_lukic_husain_2023, title={Medium Voltage Solid State Transformer for Extreme Fast Charging Applications}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131285}, abstractNote={A modular and scalable solid state transformer (SST) with direct medium voltage (MV) AC connectivity is proposed to enable DC extreme fast charging (XFC) of electric vehicles. Single-phase-modules (SPMs), each consisting of an active-front-end (AFE) stage and an isolated DC-DC stage, are connected in input-series-output-parallel (ISOP) configuration. The modular hardware is co-designed with decentralized control of the DC-DC stages where voltage and power balancing are achieved by each SPM using only its local sensor feedback; a centralized controller (CC) regulates the low voltage (LV) DC bus through the AFE stages without any sensor feedback form the SPMs. The controller architecture contrasts sharply with the prior art for MV AC to LV DC SSTs where high-speed bidirectional communication among SPMs and a CC are required for module-level voltage and power balancing, which severely limits the scalability and practical realization of higher voltage and higher power units. Detailed small-signal analysis and controller design guidelines are developed. Furthermore, a soft start-up strategy is presented. The proposed converter and control structure are validated through simulation and experimental results.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Awal, M. A. and Montes, Oscar Andres and Teng, Fei and Wang, Dakai and Bipu, Md Rashed Hasan and Yu, Wensong and Lukic, Srdjan and Husain, Iqbal}, year={2023}, pages={1528–1535} } @article{agoro_husain_2023, title={Model-Free Predictive Current and Disturbance Rejection Control of Dual Three-Phase PMSM Drives Using Optimal Virtual Vector Modulation}, volume={11}, ISSN={["2168-6785"]}, DOI={10.1109/JESTPE.2022.3171166}, abstractNote={Model-based predictive current control (MBPCC) relies heavily on adequate system modeling and accurate parameters. The detailed models of dual three-phase permanent magnet synchronous motors (PMSMs) contain mutual cross-coupling dynamics which make it difficult to extract accurate parameters. Also, some of the physical parameters of PMSMs are generally nonlinear functions of current and rotor position. In this article, a model-free predictive current control (MFPCC) based on an ultralocal model and an extended state observer is proposed for an asymmetrical dual three-phase (ADTP) PMSM. The MFPCC method is shown to provide superior current regulation when compared to the standard MBPCC approach under uncertain parameter conditions. Furthermore, the harmonic currents and the current ripple in the ADTP PMSM drive have been regulated to near-zero values by using optimized voltage vectors comprised of virtual vectors and null vectors. A generalized center-aligned pulsewidth modulation (PWM) scheme is presented to facilitate the synthesis of the optimal virtual voltage vectors for implementation on a low-cost digital signal processing platform. The performance improvements of the MFPCC with optimal virtual vector modulation are verified and compared with the conventional MBPCC method in both simulations and experiments on a surface-mount type dual three-phase PMSM.}, number={2}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Agoro, Sodiq and Husain, Iqbal}, year={2023}, month={Apr}, pages={1432–1443} } @article{bipu_dadzie_lukic_husain_2023, title={Open Circuit Switch Fault Management Method of a Multi-Phase Synchronous Buck Converter for EV Charging Application}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131648}, abstractNote={Multi-phase synchronous buck converter (MSBC) is becoming popular for the electric vehicle (EV) charging application because of its higher efficiency, smaller passive component sizes, bidirectional power flow, and output current ripple reduction through interleaving. This converter also provides higher reliability than the traditional single phase converter since its modular structure enables fault tolerant operation. Fault management in the converter requires the detection of switch fault, shut down of the faulty phase, and reconfiguration of the PWM signals for the healthy phases to avoid circulating current and high output current ripple. In addition, it is desirable that the fault management method can be implemented using the micro-controller unit (MCU) or digital signal processor (DSP), which are widely used to control power converters. This paper presents a fault management method for detecting switch faults and reconfiguring healthy phases using a DSP. The method is validated through simulations and experiments using a commercial off-the-shelf power stack.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Bipu, Md Rashed Hassan and Dadzie, David and Lukic, Srdjan and Husain, Iqbal}, year={2023}, pages={2218–2222} } @article{stevens_husain_2022, title={Automated Controller Design for the PMSM Using Dynamic Mode Decomposition}, volume={10}, ISSN={["2169-3536"]}, DOI={10.1109/ACCESS.2022.3156086}, abstractNote={This work presents a method to automatically generate a high performance controller for the permanent magnet synchronous motor (PMSM). The method consists of two components, a nominal system identification and a harmonic component identification. Both identification methods are based on dynamic mode decomposition (DMD). The nominal system identification is used to assign the feedback gaines by matching the desired closed-loop eigenvalues and eigenvectors. The harmonic system identification is used to generate vectors that are multiplied by a delay embedding of the current to predict harmonic components at the next time-step. The method is applied to two experimental test setups, one interior permanent magnet (IPM) and one surface mount permanent magnet (SPM) motor. It is shown that the automatically generated feedback controller is able to achieve a more precise transient response than the traditional rule-based PI controller. It is also shown the harmonic compensation method is able to reduce total demand distortion (TDD) on phase currents better than a traditional adaptive filter approach without the need for gain tuning. This work shows a novel approach to using DMD for the complete system identification of the PMSM, and lays the foundation for using DMD with delay embeddings to analyze and manipulate harmonic signals in a predictive way.}, journal={IEEE ACCESS}, author={Stevens, Adam and Husain, Iqbal}, year={2022}, pages={26101–26116} } @article{jung_husain_2022, title={Comparison of Subdomain Models for Outer Rotor Slotless Halbach Array Permanent Magnet Synchronous Motors}, DOI={10.1109/ITEC53557.2022.9813907}, journal={2022 IEEE/AIAA TRANSPORTATION ELECTRIFICATION CONFERENCE AND ELECTRIC AIRCRAFT TECHNOLOGIES SYMPOSIUM (ITEC+EATS 2022)}, author={Jung, Junyeong and Husain, Iqbal}, year={2022}, pages={55–60} } @article{rachi_husain_2022, title={Metal Oxide Varistor Design Optimization and Main Breaker Branch Switch Control of a Progressively Switched Hybrid DC Circuit Breaker}, volume={58}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2022.3156534}, abstractNote={In this article, metal oxide varistor (MOV) design optimization and switching control in the main circuit breaker (MCB) branch of a progressively switched hybrid dc circuit breaker (DCCB) is presented. A progressively switched hybrid DCCB can achieve faster fault isolation with reduced peak fault current magnitude and transient recovery voltage compared with a regular hybrid DCCB due to its modified switching strategy. Consequently, thermal stress on the semiconductor devices in MCB is significantly reduced. Analytical model of the system dynamics during fault isolation with progressive switching is derived to demonstrate the switching scheme’s effect on the energy-absorbing component, MOV, during turn- off process. Derived analytical model in conjunction with the displacement curve of the fast mechanical switch of the hybrid DCCB is utilized to optimize the components of the main circuit breaker branch to reduce MOV degradation through asymmetric energy dissipation. A model of the circuit breaker is built in PSCAD to validate the performance of the proposed optimization method in a 10-kV/250-A system with four stage progressive switching. Additionally, a low voltage system model at 380 V is developed in PLECS for two stage progressive switching that works as the basis of experimental validation. This includes both lookup table-based MOV model and device thermal model for junction temperature estimation. Experimental results are provided for a 380-V system to demonstrate reduced fault current peak in a progressive switching and near uniform energy absorption in optimally selected MOVs.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Rachi, Md Rifat Kaisar and Husain, Iqbal}, year={2022}, pages={3064–3075} } @article{awal_della flora_husain_2022, title={Observer Based Generalized Active Damping for Voltage Source Converters With LCL Filters}, volume={37}, ISSN={["1941-0107"]}, DOI={10.1109/TPEL.2021.3093504}, abstractNote={An observer-based active damping (AD) controller is proposed along with a unified design and implementation framework for LCL-equipped voltage source converters. The AD controller uses feedback of either of the converter-side current or the grid-side current along with that of the grid voltage. The state of the arts offer observer-based AD only for current-mode control and are limited by their inflexibility to be used in conjunction with established supplementary control methods or by the lack of damping efficacy for all configurations of LCL resonance frequency and the measured current (grid-side vs. converter-side). The proposed AD method is identically applicable for current-mode control and virtual oscillator control (VOC) where explicit voltage/current tracking loops are not used. The proposed AD controller thus overcomes a major limitation of VOC which otherwise offers robust synchronization in reduced/zero-inertia networks and enhanced fault ride-through capability. Simplified design guidelines are presented through comprehensive small-signal analysis including the observer dynamics. The proposed method is shown to be effective for both converter-side and grid-side current measurements irrespective of the LCL resonance frequency relative to the critical frequency. The analysis and design methods are validated through laboratory hardware experiments.}, number={1}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Awal, M. A. and Della Flora, Leandro and Husain, Iqbal}, year={2022}, month={Jan}, pages={125–136} } @article{feng_teng_montes_awal_bipu_husain_lukic_2022, title={Passive Capacitor Voltage Balancing of SiC-Based Three-Level Dual-Active-Bridge Converter Using Hybrid NPC-Flying Capacitor Structure}, volume={37}, ISSN={["1941-0107"]}, DOI={10.1109/TPEL.2021.3119210}, abstractNote={Three-level (TL) dual-active-bridge (DAB) converter serves a critical role in the medium-voltage (MV) solid-state-transformers in which high voltage rating and bidirectional power flow are required. The regular neutral-point-clamping (NPC) topology is easily subjected to capacitor voltage unbalance due to nonideal operating conditions. In this article, a hybrid structure incorporating NPC and flying capacitor (FC) is presented to resolve the voltage unbalance issue. The key advantages include minimal additional hardware efforts and no need to resort to active control. The FC behaves as a buffer to leverage the upper and lower capacitor so that passive voltage balance between the two dc-link capacitors can be achieved on a switching cycle basis. Closed-form analysis further reveals the impact of FC value on voltage unbalance. Moreover, the appropriate modulation scheme, switching condition, and commutation loop are evaluated to provide detailed rule of thumb to the implementation of FC circuit. Analysis shows the FC also brings favorable switching loss performance and is friendly to employ upon fast switching of wide bandgap devices such as SiC. Finally, a 1.6 kV input, 400 V output, 8 kW scaled-down hybrid NPC-FC-based DAB converter is built to validate the above analysis.}, number={4}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Feng, Hao and Teng, Fei and Montes, Oscar Andres and Awal, M. A. and Bipu, Md Rashed Hassan and Husain, Iqbal and Lukic, Srdjan}, year={2022}, month={Apr}, pages={4183–4194} } @article{agoro_husain_2022, title={Robust Deadbeat Finite-Set Predictive Current Control With Torque Oscillation and Noise Reduction for PMSM Drives}, volume={58}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2021.3130022}, abstractNote={This article proposes a unique control strategy for a deadbeat multiple vector finite-set model predictive current control with an embedded integral action (MV-FMPC) for permanent magnet synchronous motor drives. Torque ripple and phase current distortions in permanent magnet synchronous motor (PMSM) drives are minimized with the proposed controller by adopting the multiple vector approach to the finite-set model predictive control. The controller uses a hexagonal co-ordinate system to simplify the location and identification of the virtual vectors created, thereby eliminating the use of large look-up tables and reducing computational burden. When used with the proposed deadbeat prediction model, the overall steady-state performance, system robustness, and quality of disturbance rejection are improved compared to the state-of-the-art finite-set model predictive current control (FS-MPC) methods with pulsewidth modulation. The improvements are due to the modified deadbeat prediction model with integral action, the algorithm used for multiple virtual voltage identification and the retention of the cost function in the proposed method. The proposed deadbeat MV-FMPC method and its improvements over the conventional FS-MPC have been verified through simulation and experiments with an interior-type permanent magnet synchronous machine.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Agoro, Sodiq and Husain, Iqbal}, year={2022}, month={Jan}, pages={365–374} } @article{islam_mikail_kabir_husain_2022, title={Torque Ripple and Radial Force Minimization of Fractional-Slot Permanent Magnet Machines Through Stator Harmonic Elimination}, volume={8}, ISSN={["2332-7782"]}, DOI={10.1109/TTE.2021.3104758}, abstractNote={This article proposes a torque ripple minimization strategy based on minimizing interactive space harmonics of fractional-slot permanent magnet (PM) machines using a space-shifted wye–delta stator winding. A radial force analysis has also been carried out, which showed a substantial reduction in the second-order mode for these space-shifted wye–delta wound machines; this will improve the noise and vibration performance. The effectiveness of the proposed method is shown by analyzing the performances of a low-power surface-mounted permanent magnet (SPM) machine for the electric power steering (EPS) applications and a high-power interior permanent magnet (IPM) machines for the hybrid electric vehicle (HEV) applications on the 12-slot/10-pole (12 S/10 P) configuration. The proposed winding doubles the stator slot number of the base model, and as a result, the base 12 S/10 P configuration becomes 24-slot/10-pole (24 S/10 P) combination. Compared with the existing ripple minimization techniques of magnet shaping or rotor skewing, the proposed stator winding-based strategy achieves better torque ripple performance and magnet utilization leading to an improvement in average torque while reducing the amplitude of the low-order radial force. A 10-pole SPM machine has been built and tested for experimental validation of both the concept and the finite element analysis (FEA) simulation results.}, number={1}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Islam, Md Sariful and Mikail, Rajib and Kabir, Md Ashfanoor and Husain, Iqbal}, year={2022}, month={Mar}, pages={1072–1084} } @article{chattopadhyay_islam_jung_mikail_husain_2022, title={Winding Embedded Liquid Cooling for Slotless Motors in Transportation Applications}, volume={58}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2022.3191629}, abstractNote={A novel winding embedded liquid cooling (WELC) concept is presented to improve the thermal management of slotless motors for transportation applications. The concept introduces liquid cooling channels through the non-magnetic thermal plastic winding support in a slotless motor to reduce the thermal resistance between the heat source and the sink. This article demonstrates the efficacy of the WELC concept for a 11.5-kW slotless motor using computational fluid dynamics (CFD). A lumped parameter thermal network has also been developed for the WELC concept, which has been validated using the CFD analysis. The simulation results of WELC concept have been experimentally validated for an 11.5-kW slotless motor. It is shown that the WELC concept can achieve a continuous current density of 19.0 A(rms)/mm $^{2}$ for an allowable temperature rise of 80 $^{\circ }$ C; the achieved continuous current density is 35% higher than that of a conventional axial in-slot water jacket cooling. The short time (18 s) peak current density achieved with the WELC concept is 39.8 A(rms)/mm $^{2}$ .}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Chattopadhyay, Ritvik and Islam, Md Sariful and Jung, Junyeong and Mikail, Rajib and Husain, Iqbal}, year={2022}, month={Nov}, pages={7110–7120} } @article{sadilek_jang_hao_jia_barbosa_husain_2021, title={A New PFC CCM Boost Rectifier with Extended Gain and Reduced Voltage Switching for 1-ph/3-ph Universal Input On-Board Charger for Electric Vehicles}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487021}, abstractNote={A new power-factor-correction (PFC), continuous-conduction-mode (CCM) bidirectional boost rectifier for 1-ph/3-ph universal voltage input on-board charging applications is introduced. The rectifier features extended voltage gain, automatic input current sharing, and reduced voltage switching when it operates from 1-phase input voltage. Due to the extended-gain property, the proposed topology is suitable for converting low line voltages to a high dc link voltage. Switching at reduced voltage results in decreased switching losses, which allows the converter to achieve significantly increased power conversion efficiency. Unlike in standard interleaved PFC topologies, input current sharing is achieved without any sensing circuits or additional control loops. The evaluation was performed on a 3.3 kW prototype designed to operate from 85-134 V line input and deliver 775 V dc output. The prototype achieves 93.6% efficiency at 110 V RMS line input and full load. The proposed converter naturally morphs into the standard 6-switch converter for 3-phase ac voltage inputs.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Sadilek, Tomas and Jang, Yungtaek and Hao, Sun and Jia, Minli and Barbosa, Peter and Husain, Iqbal}, year={2021}, pages={556–563} } @article{cisneros_gao_ortega_husain_2021, title={A PI plus passivity-based control of a wind energy conversion system enabled with a solid-state transformer}, volume={94}, ISSN={["1366-5820"]}, DOI={10.1080/00207179.2019.1710768}, abstractNote={In this paper, we propose a new control scheme for a wind energy conversion system connected to a solid-state transformer-enabled distribution microgrid. The system consists of a wind turbine, a permanent magnet synchronous generator, a rectifier and a load which is connected to the distribution grid dc bus. The scheme combines a classical PI placed, in a nested-loop configuration, with a passivity-based controller. Guaranteeing stability and endowed with disturbance rejection properties, the controller regulates the wind turbine angular velocity to a desired value – in particular, the set-point is selected such that the maximum power from the wind is extracted – maximising the generator efficiency. The fast response of the closed-loop system makes possible to operate under fast-changing wind speed conditions. To assess and validate the controller performance and robustness under parameter variations, realistic simulations comparing our proposal with a classical PI scheme are included.}, number={9}, journal={INTERNATIONAL JOURNAL OF CONTROL}, author={Cisneros, Rafael and Gao, Rui and Ortega, Romeo and Husain, Iqbal}, year={2021}, month={Sep}, pages={2453–2463} } @article{awal_rachi_bipu_yu_husain_2021, title={Adaptive Pre-Synchronization and Discrete-Time Implementation for Unified Virtual Oscillator Control1}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595171}, abstractNote={Unified virtual oscillator controller (uVOC) is a nonlinear time-domain controller which offers robust synchronization and enhanced fault ride-through for grid-following (GFL) and grid-forming (GFM) converters without the need for switching to a back-up controller. An adaptive pre-synchronization method is proposed for uVOC to enable smooth start-up and seamless connection to an existing grid/network with non-nominal frequency and/or voltage magnitude at the point of coupling (PoC). Furthermore, we evaluate the efficacy of different discretization methods for discrete-time (DT) implementation of the nonlinear dynamics of uVOC and demonstrate that zero-order-hold (ZOH) discretization fails at sampling frequencies up to tens of kHz. DT implementation of uVOC using second-order Runge-Kutta method is presented, which offers a reasonsable compromise between computational overhead and discretization accuracy. In addition, an inductor (L) or an inductor-capacitor-inductor (LCL) type input filter used in typical voltage source converter (VSC) applications leads to voltage deviation at the converter output terminal depending on the power flow. A terminal voltage compensator (TVC) for such voltage deviation is proposed. The efficacy of the proposed methods are demonstrated through laboratory hardware experiments.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Awal, M. A. and Rachi, Md Rifat Kaisar and Bipu, Md Rashed Hassan and Yu, Hui and Husain, Iqbal}, year={2021}, pages={3418–3424} } @article{awal_tu_xu_lukic_husain_2021, title={Circulating Reactive Power and Suppression Strategies in DC Power Electronics Networks}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487129}, abstractNote={In DC electrical networks consisting of pulse-width-modulated converters, large circulating reactive power may be caused by parallel resonance among the passive filters and the parasitic elements of the interconnecting power-line cables. Such undesired circulating currents at switching frequencies and their harmonics lead to larger ripple in the network voltage, shorter component lifetime, and increased loss. In this work, the condition for such resonances is derived analytically and two suppression methods, namely, an inductor-capacitor (LC) trap filter and an L-termination filter, are proposed. Through analysis, we demonstrate that the proposed methods can guarantee resonance suppression in a generic DC network consisting of arbitrary N converters. Systematic design rules are developed. The analysis and suppression methods are validated through laboratory experiments.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Awal, M. A. and Tu, Hao and Xu, Bei and Lukic, Srdjan and Husain, Iqbal}, year={2021}, pages={796–803} } @article{sadilek_barbosa_husain_2021, title={Comparative Evaluation of Asymmetric and Symmetric Series-Capacitor Extended-Gain DC/DC Converters}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487058}, abstractNote={In this paper, an analysis of a two-phase, continuous-current-mode (CCM), pulse-width-modulated (PWM) step-up dc/dc converter family that exhibits high output-to-input voltage conversion ratio is presented. The asymmetric and symmetric series-capacitor converters feature extended gain, reduced voltage switching, and automatic input current balancing. It is shown that the symmetric converter exhibits a wider operational range with reduced voltage switching and balanced semiconductor thermal stress while the asymmetric converter offers the benefit of simple control scheme and lower component count. The developed analytical models for all operating modes of the converter family are verified through laboratory experiments on a 1-kW 600-V prototype. Moreover, a conventional interleaved boost converter is analytically and experimentally compared to the extended-gain converters to provide a baseline for deeper insights.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Sadilek, Tomas and Barbosa, Peter and Husain, Iqbal}, year={2021}, pages={1881–1888} } @article{rahman_kercher_yu_husain_2021, title={Comparative Evaluation of Current Sensors for High-Power SiC Converter Applications}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487428}, abstractNote={An evaluation procedure for comparative analysis of various current sensor technologies is proposed in which performance parameters such as latency and resolution are measured under realistic conditions for a high-power SiC converter. Testing techniques are developed to allow fair comparison between dissimilar sensor types. Experimental data is given for an open-loop Hall Effect sensor and two types of shunt-based sensors utilizing Delta-Sigma modulators.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Rahman, Dhrubo and Kercher, Michael and Yu, Wensong and Husain, Iqbal}, year={2021}, pages={2206–2210} } @article{yu_awal_tu_husain_lukic_2021, title={Comparative Transient Stability Assessment of Droop and Dispatchable Virtual Oscillator Controlled Grid-Connected Inverters}, volume={36}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2020.3007628}, DOI={10.1109/TPEL.2020.3007628}, abstractNote={With the increasing integration of power electronics interfaced distributed generators, transient stability assessment of grid-connected inverters subjected to large grid disturbances is of vital importance for the secure and resilient operation of the power grid. Dispatchable virtual oscillator control (dVOC) is an emerging approach to implement nonlinear control of grid-forming inverters. Through coordinate transformation, a simple first-order nonlinear power angle dynamic equation is uncovered from the complex oscillator dynamics. Furthermore, this article proposes a concise and straightforward graphical approach to assess transient stability of dVOC using vector field on the circle. To provide a more in-depth analysis, a complete large-signal model is derived and the impact of dVOC voltage amplitude dynamics is analyzed. For comparison, transient stability of the currently prevalent droop control is also assessed using phase portraits. Salient transient stability features of dVOC and droop control during grid faults are summarized and compared. The theoretical analysis is validated by controller hardware-in-the-loop testbed using industry-grade hardware.}, number={2}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Yu, Hui and Awal, M. A. and Tu, Hao and Husain, Iqbal and Lukic, Srdjan}, year={2021}, month={Feb}, pages={2119–2130} } @article{chowdhury_tesfamicael_islam_husain_2021, title={Design Optimization of a Synchronous Reluctance Machine for High-Performance Applications}, volume={57}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2021.3091416}, abstractNote={The article presents a torque ripple minimization process using symmetrical rotor flux barrier shaping for synchronous reluctance (SyncRel) machines. High-performance applications demand stringent torque-speed, torque ripple, noise, and vibration requirements to satisfy the overall system performance. An iterative design approach incorporating electromagnetic, structural, and thermal analyses is presented that led to the design of a SyncRel motor with low torque ripple and minimized second-order vibration mode. The contributions demonstrated that the 30-slot, 4-pole SrncRel machine is a viable option for high-performance and packaging-constrained applications. Global response surface method that has the capability for parallel analysis has been used for the multiobjective optimization problem. A 2D finite element (FE) tool with the HyperStudy optimization routine has been used to implement the proposed design process. A quick and easy-to-use motor parameter-based model along with 2D FE analysis is used to evaluate the performance of the optimized design. Experimental results are provided to validate the iterative and comprehensive design, and design procedure.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Chowdhury, Mazharul and Tesfamicael, Abraham and Islam, Mohammad and Husain, Iqbal}, year={2021}, month={Sep}, pages={4720–4732} } @article{rachi_husain_2021, title={Design and Development of A Hybrid DC Circuit Breaker for 380V DC Distribution System}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487071}, abstractNote={Design and operation of a hybrid DC circuit breaker for 380V DC distribution system is presented in this work. A hybrid DC circuit breaker offers reduced on-state loss compared to its full solid-state alternative while ensuring arc-free, fast current interruption. Power electronic converters’ current limiting capability during overload in a DC distribution system can be leveraged to accommodate slow response time of mechanical switch compared to its solid-state counterpart to increase system efficiency during normal operation. A hybrid circuit breaker for a 380V/10kW system, along with its control and device thermal models, is implemented in PLECS. Operational and thermal simulation results are provided to validate safe breaker operation. Additionally, a compact hybrid DC circuit breaker design is presented and a prototype has been fabricated. Performance of the constructed hybrid DC circuit breaker has been evaluated experimentally for a scaled down 380V/5kW DC system to demonstrate very low on-state loss and arc-free current interruption.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Rachi, Md Rifat Kaisar and Husain, Iqbal}, year={2021}, pages={1122–1127} } @article{rachi_cen_bipu_khan_husain_2021, title={Design and Development of a Multi-Port Converter for Marine Microgrid Applications}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595808}, abstractNote={In this work, a multi-port converter (MPC) design is presented that works as the key building block of a marine microgrid. An emulated wave energy converter (WEC) serves as the renewable energy resource of this microgrid system. The proposed MPC is comprised of a WEC interfacing port, energy storage port, and a split-phase AC load/grid port. Stable power exchange among these dissimilar energy resources are facilitated through a 400V internal DC bus. The full MPC design along with its control and thermal model is developed and implemented in PLECS. Commercially available SiC power modules have been used to leverage its high switching frequency capability that to achieve compact system design with reduced passive component sizes. Individual controller for each energy resource interfacing converter is analyzed, developed and implemented initially. A state-machine is developed utilizing these discrete controllers for MPC operation where all three ports are active simultaneously. These discretized controllers along with voltage/current sensor models with limited bandwidth and response delay in the feedback path are implemented in PLECS to emulate practical controller deployment. Simulation results are provided to validate both the power stage and the discrete controller design. Furthermore, iterative thermal analysis is carried out to have a realistic estimation of the device junction temperature during rated condition to evaluate the efficacy of the thermal management system. Finally, a virtual prototype design of the MPC is presented.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Rachi, Md Rifat Kaisar and Cen, Siye and Bipu, Md Rashed Hassan and Khan, Mehnaz Akhter and Husain, Iqbal}, year={2021}, pages={1184–1190} } @article{sadilek_jang_barbosa_husain_2021, title={Design and Evaluation of SiC Active Soft-Switching Cell for 1-ph/3-ph Universal Voltage Input PFC for On-Board Charger Applications}, ISSN={["2473-7631"]}, DOI={10.1109/ITEC51675.2021.9490179}, abstractNote={A detailed analysis and experimental evaluation of a continuous-conduction-mode (CCM), pulse-width-modulated (PWM), boost-type active soft-switching cell suitable for 1-ph/3-ph universal-voltage-input PFC for on-board charging (OBC) applications is introduced. The soft-switching cell features zero-voltage switching (ZVS) of all switches, reduced reverse-recovery loss at any operating point, and simple control. The cell achieves high efficiency for converting low line voltage to the high dc-link voltage required for the OBC dc-dc converter. The evaluation of the concept was performed on a single-phase leg 3.4 kW prototype designed to operate at 220 V RMS line input and deliver 650 V output. The prototype achieves 97.8% efficiency at full load and 100 kHz switching frequency. The soft-switching PFC rectifier concept naturally morphs between an interleaved totem-pole converter for 1-ph ac line voltage and a 3-ph converter for 3-ph ac line voltage.}, journal={2021 IEEE TRANSPORTATION ELECTRIFICATION CONFERENCE & EXPO (ITEC)}, author={Sadilek, Tomas and Jang, Yungtaek and Barbosa, Peter and Husain, Iqbal}, year={2021}, pages={738–743} } @article{latif_husain_2021, title={Design and analysis of an induction motor for an enhanced constant power region with electronic pole changing}, DOI={10.1109/IEMDC47953.2021.9449577}, abstractNote={Pole changing motors can be very useful for traction applications, which require high torque at low speeds and an extended speed range of operation. The dual pole operation can be used to extract high torque during starting with a high pole configuration and an increased constant power region with a lower pole operation. Although pole changing motors have been studied in the past, there is essentially no research related to how a motor can be optimized for improved performance in terms of the overall torque-speed characteristics of operation. In this paper, we discuss the design and analysis of a 4-pole/2-pole induction motor using the Finite Element Analysis and analytical computation tools in Motor-CAD software. An induction motor is designed and optimized for improved performance for the entire range of operation. Torque and power characteristics of the pole changing motor are shown to have enhanced performance in the constant power region in comparison to the baseline motor.}, journal={2021 IEEE INTERNATIONAL ELECTRIC MACHINES & DRIVES CONFERENCE (IEMDC)}, author={Latif, Taohid and Husain, Iqbal}, year={2021} } @article{husain_ozpineci_islam_gurpinar_su_yu_chowdhury_xue_rahman_sahu_2021, title={Electric Drive Technology Trends, Challenges, and Opportunities for Future Electric Vehicles}, volume={109}, ISSN={["1558-2256"]}, DOI={10.1109/JPROC.2020.3046112}, abstractNote={The transition to electric road transport technologies requires electric traction drive systems to offer improved performances and capabilities, such as fuel efficiency (in terms of MPGe, i.e., miles per gallon of gasoline-equivalent), extended range, and fast-charging options. The enhanced electrification and transformed mobility are translating to a demand for higher power and more efficient electric traction drive systems that lead to better fuel economy for a given battery charge. To accelerate the mass-market adoption of electrified transportation, the U.S. Department of Energy (DOE), in collaboration with the automotive industry, has announced the technical targets for light-duty electric vehicles (EVs) for 2025. This article discusses the electric drive technology trends for passenger electric and hybrid EVs with commercially available solutions in terms of materials, electric machine and inverter designs, maximum speed, component cooling, power density, and performance. The emerging materials and technologies for power electronics and electric motors are presented, identifying the challenges and opportunities for even more aggressive designs to meet the need for next-generation EVs. Some innovative drive and motor designs with the potential to meet the DOE 2025 targets are also discussed.}, number={6}, journal={PROCEEDINGS OF THE IEEE}, author={Husain, Iqbal and Ozpineci, Burak and Islam, Md Sariful and Gurpinar, Emre and Su, Gui-Jia and Yu, Wensong and Chowdhury, Shajjad and Xue, Lincoln and Rahman, Dhrubo and Sahu, Raj}, year={2021}, month={Jun}, pages={1039–1059} } @article{chattopadhyay_islam_boldea_husain_2021, title={FEA Characterization of Bi-Axial Excitation Machine for Automotive Traction Applications}, DOI={10.1109/IEMDC47953.2021.9449514}, abstractNote={Bi-axial excitation generator for automobiles (BEGA) machines are ideally suitable for unity power factor at the base speed which would give the best power density and lowest cost for a traction-motor inverter system. In this paper, three different designs of bi-axial excitation motors are presented: One employing rare-earth free ferrite magnets and two employing NdFeB magnets. The permanent magnets are oriented along the q-axis and are used to compensate the stator flux in order to achieve higher power factor. This reduces the required inverter size thus bringing down the overall system cost. The flux compensation is analyzed using 2D FEA and the motor performances are compared to other commonly used traction motor topologies.}, journal={2021 IEEE INTERNATIONAL ELECTRIC MACHINES & DRIVES CONFERENCE (IEMDC)}, author={Chattopadhyay, Ritvik and Islam, Md Sariful and Boldea, Ion and Husain, Iqbal}, year={2021} } @article{luo_awal_yu_husain_2021, title={FPGA-Based High-Bandwidth Motor Emulator for Interior Permanent Magnet Machine Utilizing SiC Power Converter}, volume={9}, ISSN={["2168-6785"]}, DOI={10.1109/JESTPE.2020.3015179}, abstractNote={A high-bandwidth (>20 kHz) motor emulator (ME) prototype for ac machines, utilizing field programmable gate array (FPGA)-based hybrid model predictive control (MPC) and a high fidelity motor model and implemented with a voltage source power converter, and fast-switching SiC devices, is presented in this article. The hybrid MPC incorporates a unique gate stitching modulation strategy that synchronizes the inverter switching state with the ME switching state for an accurate representation of the emulated motor currents in the physical inverter hardware output. The gate stitching MPC hybrid algorithm avoids the need for an excessively high switching frequency of the ME power converter. The developed high-bandwidth ME can emulate up to the switching ripple current of the inverter under test (IUT) where the current slope can change up to six times within one switching period when using space vector pulse width modulation (PWM). The FPGA-based fast iterating online motor model is another key component which along with the high-performance ME current regulation algorithm can accurately emulate the motor current. The bandwidth achieved far exceeds that of existing ME solutions that can only emulate fundamental current and only a few orders of harmonic content. The high bandwidth also allows the use of a small line inductor, which reduces the size and cost of the ME system. Simulation and experiment results are provided to the FPGA implementation and validate the high-bandwidth current emulating capability.}, number={4}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Luo, Yukun and Awal, M. A. and Yu, Wensong and Husain, Iqbal}, year={2021}, month={Aug}, pages={4340–4353} } @article{islam_mikail_husain_2021, title={Field Weakening Operation of Slotless Permanent Magnet Machines Using Stator Embedded Inductor}, volume={57}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2021.3061043}, abstractNote={This article presents a comprehensive design methodology to improve the field weakening (FW) operation of low inductance slotless permanent magnet synchronous machines (PMSMs). The proposed concept of using a stator embedded inductor integrated with the torque producing machine windings helps achieve a wide constant power speed range (CPSR) and a desired torque/speed characteristics. Key performance parameters including system efficiency and PWM induced current ripple are summarized for scenarios with and without the embedded inductor in the entire operating range using 2-D finite element analysis. The concept helps to achieve the desirable extended torque/speed range. It also helps to improve the efficiency beyond the base speed operation for a high speed, high power machine. In addition to achieving desired CPSR, this method also helps to reduce the PWM induced current ripple, short circuit current, and current ripple induced core losses. A slotless machine with the integrated embedded inductor has been designed following the proposed design guidelines to extend the CPSR, and a prototype motor has been built to validate the simulation results with the experimental results.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Islam, Md Sariful and Mikail, Rajib and Husain, Iqbal}, year={2021}, pages={2387–2397} } @article{islam_agoro_chattopadhyay_husain_2021, title={Heavy Rare Earth Free High Power Density Traction Machine for Electric Vehicles}, DOI={10.1109/IEMDC47953.2021.9449585}, abstractNote={A compact, heavy rare earth free permanent magnet synchronous machine with a volumetric power density of 50kW/liter is designed for electric traction applications. This is facilitated by innovations in the stator winding topology, magnet arrangement, and cooling technique. A 24-slot/10-pole dual three-phase asymmetric winding layout is adopted to improve power density, reduce harmonic losses, and improve fault tolerant capabilities. Furthermore, a novel segmented V-type magnet arrangement is proposed to address the demagnetization issues of the heavy rare earth free magnets under extreme temperatures and negative electromagnetic fields. An extensive finite element analysis has been conducted and results are presented to show the electromagnetic and demagnetization performance as well as the thermal capabilities and structural integrity of the proposed design.}, journal={2021 IEEE INTERNATIONAL ELECTRIC MACHINES & DRIVES CONFERENCE (IEMDC)}, author={Islam, Md Sariful and Agoro, Sodiq and Chattopadhyay, Ritvik and Husain, Iqbal}, year={2021} } @article{rachi_khan_husain_2021, title={Local Measurement-Based Protection Coordination System for a Standalone DC Microgrid}, volume={57}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2021.3091945}, abstractNote={A reliable protection coordination system between the power electronic converters and solid-state device-based fast protection unit in a standalone dc microgrid supplied by a wave energy converter (WEC) and an energy storage unit is presented. A system model with solid-state circuit breakers is developed in Piecewise Linear Electrical Circuit Simulation (PLECS) to analyze the steady-state operation as well as faulted conditions. The effect of both resistive and constant power loads on a current-limited bus controlling converter behavior during an overload event is analyzed theoretically. Also, the variation in the WEC power output and its effect on bus voltage during overload are investigated. The analysis has led to a novel dual current-voltage feedback-based protection coordination system. The method does not require any communication between the solid-state circuit breakers and converters and eliminates the need for adaptive updating of the overcurrent threshold with varying renewable generation output. Bus capacitor discharge during a short-circuit is analyzed theoretically as well to formulate an instantaneous trip threshold selection utilizing device gate driver functionality. The proposed protection coordination system ensures rapid fault isolation and continued power delivery to the healthy segments. An SiC-based bidirectional, solid-state dc circuit breaker prototype is designed and fabricated, which has been used to implement the proposed protection method with a 380-V dc bus-based system.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Rachi, Md Rifat Kaisar and Khan, Mehnaz Akhter and Husain, Iqbal}, year={2021}, month={Sep}, pages={5332–5344} } @article{latif_jaffar_husain_2021, title={Loss Minimization Control of an Electronic Pole Changing 4-pole/2-pole Induction Motor}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595843}, abstractNote={A pole changing motor can operate in a dual pole configuration for high torque during low-speed operation with a higher pole configuration and an enhanced constant power speed region at higher speeds with a lower pole configuration. In these motors, electronic pole changing is accomplished by changing the currents in certain windings by using an inverter. Although pole-changing transition on the fly has been explored in literature, the specifics as to when a pole change is required is yet to be established. This paper discusses the control of a 4-pole/2-pole induction motor where the controller initiates a pole change from one pole configuration to another to minimize the power loss of the motor when the operating region overlaps for the two pole configurations. Results from Simulink based on parameters extracted from Motor-CAD are provided to validate the control method. The pole changing control results demonstrate a smooth torque transition while minimizing the motor loss. The open loop experimental results are also given.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Latif, Taohid and Jaffar, Mohamed Zubair M. and Husain, Iqbal}, year={2021}, pages={4097–4102} } @article{chowdhury_islam_husain_2021, title={Modeling of Electromagnetic Torque Including Ripple Harmonics in Synchronous Reluctance Machines}, volume={57}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2021.3107806}, abstractNote={In this article, an analytical model to predict the instantaneous torque profile in a synchronous reluctance (SyncRel) machine is developed, which can predict the machine's torque performance based on either inductance or flux-linkage harmonics. High-performance torque-ripple-sensitive applications have stringent torque ripple and noise and vibration requirements to satisfy the overall system requirements. The prediction of the torque ripple is critical in these applications to identify the root cause and then mitigate the torque ripple through design alternations under different loading (current) conditions of the machine. The developed analytical model provides a simpler, intuitive, and significantly less time consuming yet reasonably accurate alternative approach compared to multiple finite-element runs on the same baseline design. The developed analytical model provides design support through fast iterations with design variations or for motor electronic controller implementation. A 2-D finite-element model has been developed to validate the proposed analytical model. The analytical model is also validated with experimental data of a 30-slot four-pole SyncRel machine.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Chowdhury, Mazharul and Islam, Mohammad and Husain, Iqbal}, year={2021}, month={Nov}, pages={5851–5863} } @article{islam_chowdhury_shrestha_islam_husain_2021, title={Multiload Point Optimization of Interior Permanent Magnet Synchronous Machines for High-Performance Variable-Speed Drives}, volume={57}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2020.3040141}, abstractNote={Multiobjective and multiload point design optimization of an interior permanent magnet (IPM) synchronous machine using a global response surface method to achieve low torque ripple with high average torque over the entire speed range is presented in this article. The approach consisting of a set of design steps and multiobjective optimization to obtain high-performance electric machines with optimum usage of rare-earth materials for mass production is presented. The design optimization has been applied to a 12-slot eight-pole IPM machine with two different rotor structures to arrive at the optimized design for a variable-speed high-performance application. Motor parameters are extracted under different load conditions to predict the torque/speed performance of the motors. The proposed design approach provides a machine design with maximized output torque, improved torque density, lower torque ripple, and optimum usage of rare-earth materials. Finally, the finite-element-based modeling results are validated with the experimental results.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Islam, Md Sariful and Chowdhury, Mazharul and Shrestha, Amina and Islam, Mohammad and Husain, Iqbal}, year={2021}, month={Jan}, pages={427–436} } @article{oh_husain_2021, title={Optimal Torque Distribution of Dual-Motor All-Wheel Drive Electric Vehicles for Maximizing Motor Energy Efficiency}, ISSN={["2473-7631"]}, DOI={10.1109/ITEC51675.2021.9490089}, abstractNote={This paper presents the suitable choices for the front- and rear-wheel motors of a dual-motor all-wheel drive electric vehicle (EV) based on the optimal torque distribution for high efficiency. Interior permanent magnet synchronous, induction, and PM-assisted synchronous reluctance machines are among the top machine contenders for either of the axles of the vehicle. The fuel economy analysis according to motor combinations and torque distribution is conducted. The B-segment EV is used for fuel economy tests with the UDDS and the HWY driving cycles in MATLAB/SIMULINK. The simulation results show that induction machine for the front-wheel motor with the proposed optimal torque distribution when the rear-wheel motor is the permanent magnet synchronous machine reduces the total amount of motor energy consumption.}, journal={2021 IEEE TRANSPORTATION ELECTRIFICATION CONFERENCE & EXPO (ITEC)}, author={Oh, Mingi and Husain, Iqbal}, year={2021}, pages={188–193} } @article{chattopadhyay_islam_mikailz_husain_2021, title={Partial Discharge Analysis and Insulation Design of High Speed Slotless Machine for Aerospace Applications}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595949}, abstractNote={Slotless motor is a suitable propulsion component candidate for high speed aerospace applications due to their light Rotor Support weight, low iron losses and superior efficiency at higher speeds (high frequency) of operation. However, insulation design for Halbach Array the winding, non-magnetic teeth and the surrounding regions Stator Windings for a slotless machine require added attention during the design process due to the low pressure and high altitudes associated with aerospace applications. This paper presents the analysis and Winding Support insulation design of a slotless motor with random wound magnet Stator Lamination wire conductors for a low pressure environment. The effect of potting thickness, air bubbles in the potting, relative permittivity of insulation, and slew rate on insulation design is analyzed using finite element methods.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Chattopadhyay, Ritvik and Islam, Md Sariful and Mikailz, Rajib and Husain, Iqbal}, year={2021}, pages={4075–4080} } @article{bipu_awal_cen_zabin_khan_lubkeman_husain_2021, title={Secondary Voltage and Frequency Regulation for Grid Re-Synchronization in Microgrid with Unified Virtual Oscillator Controlled Multi-port Converters}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595901}, abstractNote={Unified Virtual Oscillator Controller (uVOC) is a type of oscillator based nonlinear time domain controller that achieves faster primary control response than conventional droop control as no phase-locked loop (PLL) is required. uVOC can be used effectively for either grid following or grid-forming voltage source converters. Grid-forming converter is essential for a microgrid to operate in islanded mode in addition to the more common grid-connected mode. In this paper, a secondary regulation scheme is proposed to augment the capability of uVOC based on a Multi-port Converter (MPC) by adding voltage and frequency regulation for grid re-synchronization. With this method, changing primary controller is not required and seamless transition is achieved. To implement this secondary regulation, communication or data exchange between different components is required. The network connectivity is implemented based on the RIAPS platform, an open-source distributed operating system developed for real-time control of microgrid/smartgrid systems. Finally, the suitability of proposed secondary regulation with uVOC based MPC was verified through simulation and experiment on a microgrid testbed.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Bipu, Md Rashed Hassan and Awal, M. A. and Cen, Siye and Zabin, Salina and Khan, Mehnaz and Lubkeman, David and Husain, Iqbal}, year={2021}, pages={900–905} } @article{mehta_kabir_pramod_husain_2021, title={Segmented Rotor Mutually Coupled Switched Reluctance Machine for Low Torque Ripple Applications}, volume={57}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2021.3073384}, abstractNote={Mutually coupled switched reluctance motors (MCSRMs) are alternatives in the family of reluctance machines that can overcome switched reluctance motor's (SRM's) system-level integration and control challenges by utilizing standard three-phase voltage source inverters. In this article, a novel segmented-rotor, fractional-slot, tooth-wound MCSRM with notched rotor design is presented, which has very low torque ripple compared to other machine types in the SRM family. The torque ripple is reduced to 3.6% without utilizing any current profiling techniques or torque sharing functions. The ripple minimization is achieved primarily through rotor segment shaping, which has a strong influence on stator flux densities, flux linkages, and torque harmonics. The design strategy, along with the optimization details, is presented for a 120 W, 12 slot-8 pole MCSRM. The designed MCSRM is prototyped for experimental verification and validation of the finite element analysis results and design methodology.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Mehta, Siddharth and Kabir, Md Ashfanoor and Pramod, Prerit and Husain, Iqbal}, year={2021}, pages={3582–3594} } @article{mehta_pramod_husain_kabir_2021, title={Small-Signal Modeling of Mutually Coupled Switched Reluctance Motor}, volume={57}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2020.3030873}, abstractNote={A small-signal model based on the net flux method is developed for mutually coupled switched reluctance machines (MCSRMs) to facilitate the design and analysis of the current controller for the drive. The underlying methodology of using net flux allows MCSRM modeling on a per-phase basis which reduces the time involved in characterizing the motor and the number of machine model parameters. A comprehensive theory of modeling the machine and extracting the machine parameters with analytical derivations is provided. Furthermore, a complete design procedure and analysis for a proportional-integrator controller is presented. The derived MCSRM small-signal model is useful to evaluate the controller's current tracking performance, disturbance rejection capability, and response features over a wide speed range. Simulation analysis and experimental results for a 3 phase, 150 W, full-pitched MCSRM drive system are provided both for small-signal model validation and current controller performance evaluation.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Mehta, Siddharth and Pramod, Prerit and Husain, Iqbal and Kabir, Md Ashfanoor}, year={2021}, month={Jan}, pages={259–271} } @article{awal_husain_2021, title={Transient Stability Assessment for Current-Constrained and Current-Unconstrained Fault Ride Through in Virtual Oscillator-Controlled Converters}, volume={9}, ISSN={["2168-6785"]}, DOI={10.1109/JESTPE.2021.3080236}, abstractNote={Unified virtual oscillator controller (uVOC) inherits the rigorous analytical foundation offered by oscillator-based grid-forming (GFM) controllers and enables fast overcurrent limiting and fault ride through (FRT). Control design for effective FRT requires transient stability analysis. Existing transient stability analysis methods and studies are limited in either considering only current-unconstrained scenarios or neglecting the simultaneous power-angle and voltage dynamics. Under current-constrained faults, the voltage and power-angle dynamics are strongly coupled and both play critical roles in determining transient stability. Therefore, decoupled analysis of the two, typically used in transient stability studies, does not offer comprehensive insight into the system dynamics. In this work, a comprehensive modeling and analysis method for transient stability in uVOC-based converters is developed under both current-saturated and current-unsaturated symmetrical ac faults. We utilize a phase-plane analysis of the overall system in a single graphical representation to obtain holistic insights into the coupled voltage and power-angle dynamics. The FRT controller and the analysis method have been validated through simulations and hardware experiments. The results demonstrate that uVOC is not constrained by a critical clearing angle unlike droop and virtual synchronous machine (VSM)-type second-order controllers.}, number={6}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Awal, M. A. and Husain, Iqbal}, year={2021}, month={Dec}, pages={6935–6946} } @article{awal_husain_2021, title={Unified Virtual Oscillator Control for Grid-Forming and Grid-Following Converters}, volume={9}, ISSN={["2168-6785"]}, DOI={10.1109/JESTPE.2020.3025748}, abstractNote={A unified virtual oscillator controller (uVOC) is proposed, which enables a unified analysis, design, and implementation framework for both grid-forming (GFM) and grid-following (GFL) voltage-source converters (VSCs). Oscillator-based GFM controllers, such as dispatchable virtual oscillator control (dVOC), offer a rigorous analytical framework with enhanced synchronization but lack effective fault handling capability, which severely limits practical application. The proposed uVOC facilitates synchronization with an arbitrarily low grid voltage and fast overcurrent limiting; this enables effective fault ride-through unlike existing GFM controllers which typically switch to a back-up controller during the fault. GFM operation with uVOC is achieved in both grid-connected and islanded modes with seamless transitions between the two. In GFL converters, bidirectional power flow control and dc bus voltage regulation are achieved with uVOC. No phase-locked loop (PLL) is required for either GFL or GFM operation circumventing the synchronization issues associated with PLLs in weak grid applications. Detail small-signal models for GFM and GFL operation have been developed, and the systematic design guidelines for controller parameters are provided. The proposed controller is validated through hardware experiments in a hybrid ac-dc microgrid.}, number={4}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Awal, M. A. and Husain, Iqbal}, year={2021}, month={Aug}, pages={4573–4586} } @article{awal_husain_2021, title={Unified Virtual Oscillator Control for Synchronization Under Ultra-Weak Grid Conditions}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487212}, abstractNote={A unified virtual oscillator controller (uVOC) with fast power control response is proposed for enhanced synchro-nization under ultra-weak grid conditions. The recently proposed uVOC offers a unified analysis, design, and implementation framework for both grid-following and grid-forming converters; leveraging its superior synchronization capability, enhanced fault ride-through response is achieved without the need for a back-up controller during faults. In this work, we propose an improved uVOC design and implementation which enables fast power-flow control. Through analysis, we demonstrate that the proposed controller retains synchronization as long as a feasible equilibrium exists. Furthermore, using dynamic reactive power control the feasible power-flow range is extended under ultra-weak grid conditions. Systematic design guidelines for controller parameters are presented. The analysis and design are validated through hardware experiments.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Awal, M. A. and Husain, Iqbal}, year={2021}, pages={105–110} } @article{sadilek_kumar_jang_barbosa_husain_2020, title={A Low-THD Two-Switch PFC DCM Boost Rectifier for Aviation Applications}, volume={6}, ISSN={["2332-7782"]}, DOI={10.1109/TTE.2020.2993925}, abstractNote={In this article, a new two-switch, single-phase, power-factor-correction, discontinuous-conduction-mode boost rectifier that features zero-voltage switching turn on and can achieve less than 5% input-current total harmonic distortion (THD) by injecting a simple feedforward signal obtained from input and output voltages to the output voltage feedback control is introduced. Since low THD is achieved without high- bandwidth active current shaping control, the proposed topology is suitable for modern aviation applications that require line frequency up to 800 Hz. The evaluation was performed on a 320-W prototype designed to operate from 94-134-V line input and deliver 220-V dc output. The prototype achieves 3.3% THD at full load over the line frequency range from 360 to 800 Hz and meets the required harmonic limits specified by the DO-160 standard that describes the environmental conditions and test procedures for airborne equipment.}, number={4}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Sadilek, Tomas and Kumar, Misha and Jang, Yungtaek and Barbosa, Peter and Husain, Iqbal}, year={2020}, month={Dec}, pages={1755–1766} } @article{islam_kabir_mikail_husain_2020, title={A Systematic Approach for Stator MMF Harmonic Elimination Using Three-Layer Fractional Slot Winding}, volume={56}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2020.2984195}, abstractNote={A systematic approach based on a novel space-shifted three-layer winding (SSTLW) to eliminate both the sub- and superharmonics of fractional slot concentrated winding ac machines is presented. In this proposed three-layer fractional slot winding, the number of turns in one layer and the relative positions of other two layers are optimized to cancel subharmonics. The cancellation of superharmonics is achieved through series connection of two SSTLWs through effective doubling of the number of slots. The cancellation of the dominant sub- and superharmonics using this approach leads to reducing the total harmonic distortion, torque ripple, PM eddy current loss, and rotor core loss, while simultaneously improving power factor and saliency ratio. The proposed design methodology and ensuring improvements have been validated through finite element analysis for the widely used 12-slot/10-pole and 18-slot/14-pole permanent magnet synchronous machine (PMSM) configurations. A prototype three-layer winding is built for a 10-pole PMSM to validate the simulation results experimentally.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Islam, Md Sariful and Kabir, Md Ashfanoor and Mikail, Rajib and Husain, Iqbal}, year={2020}, pages={3516–3525} } @article{islam_husain_ahmed_sathyan_2020, title={Asymmetric Bar Winding for High-Speed Traction Electric Machines}, volume={6}, ISSN={["2332-7782"]}, DOI={10.1109/TTE.2019.2962329}, abstractNote={A new asymmetric bar winding concept along with the analysis and benefits for high-speed traction electric machines is presented. The objective is to reduce the ac losses, especially at high speeds, utilizing optimized and asymmetric conductor heights within a slot for bar-wound stators. Detailed winding diagram, height optimization, ac loss analysis, and thermal performance are presented for both symmetric, i.e., conventional, and asymmetric bar windings. The proposed idea is validated using the closed-form analytical equation and 2-D time-stepped finite-element analysis (FEA). A substantial reduction of ac losses and improvement in continuous power over the wide operation range is achieved as demonstrated for a 12-pole, 100-kW high-speed (15 000 r/min) PM traction machine. Thermal performance analysis using forced liquid cooling is also included. The design and analysis methodology is presented to support high-speed traction electric machine designers meet the ever-increasing demand on efficiency and performance with bar-type windings.}, number={1}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Islam, Md Sariful and Husain, Iqbal and Ahmed, Adeeb and Sathyan, Anand}, year={2020}, month={Mar}, pages={3–15} } @article{awal_bipu_montes_feng_husain_yu_lukic_2020, title={Capacitor Voltage Balancing for Neutral Point Clamped Dual Active Bridge Converters}, volume={35}, ISSN={["1941-0107"]}, DOI={10.1109/TPEL.2020.2988272}, abstractNote={A capacitor voltage balancing method is proposed for a full-bridge neutral point diode clamped (NPC) dual-active bridge (DAB) converter. In existing literature, capacitor voltage balancing is achieved by actively selecting between the small voltage vectors, i.e., connecting either the upper or the lower capacitor on the dc bus to the transformer winding, on the basis of measured voltage mismatch. These balancing methods are dependent on the direction of power flow through the DAB converter. In this work, we propose a voltage balancing controller, which is independent of power flow direction and does not require adjustments of active voltage vectors through the modulator. Irrespective of the direction of transformer current, by dynamically shifting the switching instants of the inner switch pairs in the two NPC legs during the free-wheeling/zero voltage vector time, either of the two capacitors can be selectively charged without introducing any offsets in the voltage-second seen by the transformer. A simple bidirectional phase-shift modulator is designed to facilitate voltage balancing irrespective of power flow direction or mode of operation. The proposed method is highly and universally effective under any converter operating condition and was verified and demonstrated through analysis, simulation, and hardware experiments using a laboratory prototype.}, number={10}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Awal, M. A. and Bipu, Md Rashed Hassan and Montes, Oscar Andres and Feng, Hao and Husain, Iqbal and Yu, Wensong and Lukic, Srdjan}, year={2020}, pages={11267–11276} } @article{awal_yu_lukic_husain_2020, title={Droop and Oscillator Based Grid-Forming Converter Controls: A Comparative Performance Analysis}, volume={8}, ISSN={["2296-598X"]}, DOI={10.3389/fenrg.2020.00168}, abstractNote={Two distinct approaches, one droop based phasor domain modeled and the other nonlinear oscillator based time domain modeled, have emerged for the analysis and control of power electronic converters at the system interface layer where these converters are integrating distributed energy resources (DERs). While the droop type controllers are based on distinct time-scale separation of control loops, purposefully slowing down the response of the DERs, the oscillator based controllers deliver fast dynamic response with accurate power sharing capability as well as stability guarantee. In this paper, we analyze both the droop and oscillator type converters in the context of grid forming converters with respect to steady state terminal response, transient stability, and harmonic compensation in converter output current or in network voltage. Simulation and experimental results are provided to demonstrate the easier implementation of oscillator based controls that can also achieve supplementary control objectives pertinent to power quality.}, journal={FRONTIERS IN ENERGY RESEARCH}, author={Awal, M. A. and Yu, Hui and Lukic, Srdjan and Husain, Iqbal}, year={2020}, month={Oct} } @article{moorthy_aberg_olimmah_yang_rahman_lemmon_yu_husain_2020, title={Estimation, Minimization, and Validation of Commutation Loop Inductance for a 135-kW SiC EV Traction Inverter}, volume={8}, ISSN={["2168-6785"]}, DOI={10.1109/JESTPE.2019.2952884}, abstractNote={With growing interests in low-inductance silicon carbide (SiC)-based power module packaging, it is vital to focus on system-level design aspects to facilitate easy integration of the modules and reap system-level benefits. To effectively utilize the low-inductance modules, busbar and interconnects should also be designed with low stray inductances. A holistic investigation of the flux path and flux cancellations in the module-busbar assembly, which can be treated as differentially coupled series inductors, is thus mandatory for a system-level design. This article presents a busbar design, which can be adopted to effectively integrate the CREE's low-inductance 1.2-/1.7-kV SiC power modules. This article also proposes a novel measurement technique to measure the inductance of the module-busbar assembly as a whole rather than deducing it from individual components. The inductance of the overall commutation loop of the inverter that encompasses the SiC power module, interconnects, and printed circuit board (PCB) busbar has been estimated using finite-element analysis (FEA). Insights gained from FEA provided the guidelines to decide the placement of the decoupling capacitors in the busbar to minimize the overall commutation loop inductance from 12.8 to 7.4 nH, which resulted in a significant reduction in the device voltage overshoot. The simulation results have been validated through measurements using an impedance analyzer (ZA) with less than 5% difference between the extracted loop inductance from FEA and measurements. The busbar design study and the measurement technique discussed in this article can be easily extended to other power module packages. Finally, the 135-kW inverter has been compared to a similar high-power inverter utilizing a laminated busbar to highlight the performance of the former.}, number={1}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Moorthy, Radha Sree Krishna and Aberg, Bryce and Olimmah, Marshal and Yang, Li and Rahman, Dhrubo and Lemmon, Andrew N. and Yu, Wensong and Husain, Iqbal}, year={2020}, month={Mar}, pages={286–297} } @article{awal_yu_tu_lukic_husain_2020, title={Hierarchical Control for Virtual Oscillator Based Grid-Connected and Islanded Microgrids}, volume={35}, ISSN={["1941-0107"]}, DOI={10.1109/TPEL.2019.2912152}, abstractNote={Virtual oscillator control (VOC) is a nonlinear time domain controller that achieves significantly faster primary control response in islanded microgrids, compared to droop or virtual synchronous machine (VSM) control. Despite its superior performance, adoption of VOC is limited due to the lack of compatible secondary regulation or grid synchronization techniques. This is attributed to the nonlinear nature of VOC that complicates secondary control design, and the third-harmonic component in VOC output voltage that severely restricts grid-tied operation. To leverage the faster primary control response characteristics of VOC, we propose a compatible hierarchical control structure that enables operation and seamless transition between islanded and grid-connected modes. In the islanded mode, the controller achieves voltage and frequency regulation and grid synchronization; in the grid-tied mode, notch filters are used to suppress harmonic currents and tertiary level power reference tracking is achieved. The proposed controllers are validated through a series of real-time hardware-in-the-loop tests and hardware experiments using laboratory inverter prototype and state-of-the-art controls and communications hardware.}, number={1}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Awal, M. A. and Yu, Hui and Tu, Hao and Lukic, Srdjan M. and Husain, Iqbal}, year={2020}, month={Jan}, pages={988–1001} } @article{mehta_kabir_husain_pramod_2020, title={Modeling of Mutually Coupled Switched Reluctance Motors Based on Net Flux Method}, volume={56}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2020.2968834}, abstractNote={Modeling and accurate estimation of mutual flux in switched reluctance motors are complex due to interphase flux interactions, magnetic saturation, and harmonics. The mutual flux contributes significantly toward torque production of mutually coupled switched reluctance motors (MCSRMs); therefore, their accurate modeling directly influences the control design. In this article, a net-flux-based machine model is proposed to model MCSRMs. The model utilizes dual-phase excitation and multiphase excitation methods to generate the flux lookup tables from the finite-element model of the MCSRM. The modeling process is simple, as it does not require the segregation of the self- and mutual flux components, and machine performance can be predicted accurately using the net flux. The proposed modeling method is validated by implementing it for a fully pitched and concentrated-wound MCSRM and evaluating accuracy against the finite-element method. Details of the developed model are presented along with its comparison with existing methods. A prototype of a fully pitched MCSRM has been built, and the model is validated experimentally. Results show that the proposed model has excellent accuracy even under saturated operating conditions.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Mehta, Siddharth and Kabir, Md Ashfanoor and Husain, Iqbal and Pramod, Prerit}, year={2020}, pages={2451–2461} } @article{mackey_rachi_peng_husain_2020, title={Optimization and Control of a Z-Source, Ultrafast Mechanically Switched, High-Efficiency DC Circuit Breaker}, volume={56}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2020.2970657}, abstractNote={A novel design of the Z-source circuit breaker topology is presented to minimize on-state losses of the protection device. An ultrafast mechanical switch is proposed to commutate the fault current and improve the controllability of the circuit breaker. Replacing the power thyristor in the Z-source circuit breaker and integrating an advanced control scheme reduces energy losses with a low-resistance mechanical contactor. The proposed design facilitates bidirectional current flow, enhances control capability for distributed energy resources, and improves ride-through capabilities during load transients. Z-source circuit breakers utilize an impedance network to create a forced current zero crossing in the event of a fault, allowing the inline thyristor to isolate the fault from the source through reverse bias. However, full load current flows through the thyristor, resulting in high loss and heat generation. The concept is validated, and a proper control scheme is developed for this circuit breaker through an analytical estimation model of the system dynamics during a fault. Simulation and modeling are performed in power systems computer aided design (PSCAD) and piecewise linear electrical circuit simulation (PLECS). Finally, an experimental laboratory prototype is tested to validate the analytical and simulation models and certify the control logic.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Mackey, Landon and Rachi, Md Rifat Kaisar and Peng, Chang and Husain, Iqbal}, year={2020}, pages={2871–2879} } @article{awal_yu_husain_2020, title={Passivity-Based Predictive-Resonant Current Control for Resonance Damping in LCL-Equipped VSCs}, volume={56}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2019.2959594}, abstractNote={In this article, we propose a frequency-domain passivity-based damping controller combined with predictive current control for LCL-filter-equipped voltage source converters (VSCs) connected to an arbitrary ac network to achieve passive VSC input admittance almost up to the Nyquist frequency. The controller guarantees resonance damping in the corresponding frequency range irrespective of the network impedance seen by the VSC. Resonant current compensation is added to eliminate the steady-state tracking error and to achieve superior disturbance rejection. We have used impedance-based method for the analysis of harmonic resonance instabilities caused by current controllers. The developed passivity-based predictive-resonant current controller is analytically shown to stabilize interactions among multiparalleled VSCs. Resonance damping capability of the proposed method is validated through simulation and hardware experiments.}, number={2}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Awal, M. A. and Yu, Wensong and Husain, Iqbal}, year={2020}, pages={1702–1713} } @article{hafiz_awal_queiroz_husain_2020, title={Real-Time Stochastic Optimization of Energy Storage Management Using Deep Learning-Based Forecasts for Residential PV Applications}, volume={56}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85084192067&partnerID=MN8TOARS}, DOI={10.1109/TIA.2020.2968534}, abstractNote={A computationally proficient real-time energy management method with stochastic optimization is presented for a residential photovoltaic (PV)-storage hybrid system comprised of a solar PV generation and a battery energy storage (BES). Existing offline energy management approaches for day-ahead scheduling of BES suffer from energy loss in real time due to the stochastic nature of load and solar generation. On the other hand, typical online algorithms do not offer optimal solutions for minimizing electricity purchase costs to the owners. To overcome these limitations, we propose an integrated energy management framework consisting of an offline optimization model concurrent with a real-time rule-based controller. The optimization is performed in receding horizon with load and solar generation forecast profiles using deep learning-based long short term memory method in rolling horizon to reduce the daily electricity purchase costs. The optimization model is formulated as a multistage stochastic program where we use the stochastic dual dynamic programming algorithm in the receding horizon to update the optimal set point for BES dispatch at a fixed interval. To prevent loss of energy during optimal solution update intervals, we introduce a rule-based controller underneath the optimization layer in finer time resolution at the power electronics converter control level. The proposed framework is evaluated using a real-time controller-hardware-in-the-loop test platform in an OPAL-RT simulator. The proposed real-time method is effective in reducing the net electricity purchase cost compared to other existing energy management methods.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Hafiz, Faeza and Awal, M. A. and Queiroz, Anderson Rodrigo and Husain, Iqbal}, year={2020}, pages={2216–2226} } @article{islam_kabir_mikail_husain_2020, title={Space-Shifted Wye-Delta Winding to Minimize Space Harmonics of Fractional-Slot Winding}, volume={56}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2020.2975766}, abstractNote={A space-shifted wye-delta winding for fractional-slot concentrated winding (FSCW) is proposed that can simultaneously cancel both sub- and super-order harmonics of its stator MMF. The new winding concept proposes two sets of three-phase windings by doubling the number of stator slots connected in the wye-delta configuration. These two winding sets are shifted in space with respect to each other and are connected in series. The wye-delta configuration eliminates subharmonics and enhances the torque-producing component, whereas their relative shifting angle eliminates the dominant higher order harmonics to provide a cleaner and enhanced MMF spectrum. In FSCW motors, dominant space harmonics other than the torque-producing component give rise to undesirable losses in the magnet and rotor core. The efficacy of the proposed method is demonstrated through its stator MMF, harmonic spectrum, and motor performance using finite-element analysis. The application of the proposed winding to a permanent magnet (PM) machine showed dominant sub- and super-order harmonics cancellation, total harmonic distortion reduction, and magnetic loss reduction along with torque density and power factor improvements. A prototype PM machine is built, and the performance of the proposed concept is verified experimentally.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Islam, M. D. Sariful and Kabir, Md Ashfanoor and Mikail, Rajib and Husain, Iqbal}, year={2020}, pages={2520–2530} } @article{husain_hasan_sozer_husain_muljadi_2019, title={Cogging Torque Minimization in Transverse Flux Machines}, volume={55}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2018.2868541}, abstractNote={This paper presents the design considerations in cogging torque minimization in two types of transverse flux machines. The machines have a double stator-single rotor configuration with flux concentrating ferrite magnets. One of the machines has pole windings across each leg of an E-Core stator. Another machine has quasi-U-shaped stator cores and a ring winding. The flux in the stator back iron is transverse in both machines. Different methods of cogging torque minimization are investigated. Key methods of cogging torque minimization are identified and used as design variables for optimization using a design of experiments (DOEs) based on the Taguchi method. A multilevel DOE is proposed as an optimization method to reach an optimum solution with minimum simulations. The case study is analyzed in a two-level DOE optimization. Finite element analysis (FEA) is used to study the different effects. Two prototypes are fabricated for validating the FEA results.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Husain, Tausif and Hasan, Iftekhar and Sozer, Yilmaz and Husain, Iqbal and Muljadi, Eduard}, year={2019}, pages={385–397} } @article{hafiz_queiroz_husain_2019, title={Coordinated Control of PEV and PV-Based Storages in Residential Systems Under Generation and Load Uncertainties}, volume={55}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85075497159&partnerID=MN8TOARS}, DOI={10.1109/TIA.2019.2929711}, abstractNote={Energy storage deployment in residential and commercial applications is an attractive proposition for ensuring proper utilization of solar photovoltaic (PV) power generation. Energy storage can be controlled and coordinated with PV generation to satisfy electricity demand and minimize electricity purchases from the grid. For optimal energy management, PV generation and load demand uncertainties need to be considered when designing a control method for the PV-based storage system. Another resource available at the residential level is the plug-in electric vehicle (PEV) which also has bi-directional power flow capability. The charging and discharging routines of the PEV can be controlled to help reduce the energy drawn from the power grid during peak hours. In this paper, a method of coordinated optimal control between PV-based storage and PEV storage is proposed considering the stochastic nature of solar PV generation and load demand. The stochastic dual dynamic programming algorithm is employed to optimize the charge/discharge profiles of PV-based storage and PEV storage to minimize the daily household electricity purchase cost from the grid. Simulation analysis shows the advantage of the coordinated control compared to other control strategies.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Hafiz, Faeza and Queiroz, Anderson Rodrigo and Husain, Iqbal}, year={2019}, pages={5524–5532} } @article{kabir_jaffar_wan_husain_2019, title={Design, Optimization, and Experimental Evaluation of Multilayer AC Winding for Induction Machine}, volume={55}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2019.2910775}, abstractNote={This paper presents the design characterization, optimization, and experimental validation of a multilayer ac winding that provides a high quality rotating MMF with reduced end-turn length. Harmonics in the airgap MMF have been characterized with standard winding functions and verified using finite element analysis (FEA). The multilayer winding design is optimized for a commercial premium efficiency/IE3 benchmark machine using grid multiobjective genetic algorithm (GMGA) and a prototype has been built. Performance of the designed motor has been verified with both FEA and experiments. Evaluation under IEEE 112 test standard demonstrates that by only updating its stator winding design, the designed motor can achieve IE4 class efficiency under the same frame size and cooling type as its IE3 class benchmark.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Kabir, Md Ashfanoor and Jaffar, Mohamed Zubair M. and Wan, Zhao and Husain, Iqbal}, year={2019}, pages={3630–3639} } @article{hafiz_queiroz_fajri_husain_2019, title={Energy management and optimal storage sizing for a shared community: A multi-stage stochastic programming approach}, volume={236}, ISSN={["1872-9118"]}, DOI={10.1016/j.apenergy.2018.11.080}, abstractNote={Abstract The aim of this paper is to propose a new energy management framework and storage sizing for a community composed of multiple houses and distributed solar generation. Uncertainties associated with solar generation and electricity demand are included to make the mathematical models more realistic, and as a result, provide more accurate control strategies to manage storage devices utilization. To evaluate that, a multi-stage stochastic program model designed to minimize community electricity purchase cost per day is used to support decision-making by creating control policies for energy management. Two different strategies are created to represent the interest of a single household (the individual energy management - IEM) and households that share their assets with the community (shared energy management - SEM). Our strategies consider time-of-use rates (ToU), load and resource variation during different seasons, with their distinct days of the year, to calculate net present value (NPV) associated with the energy savings. IEM and SEM are then used in a framework designed to establish the requirement of optimal energy storage size for each house of the community based on NPV values. The results of this study for an analysis considering a community with five houses show that the proposed SEM strategy reduces the overall electricity purchase costs for a summer day up to 11% and 3% compared with heuristic and IEM control respectively. Moreover, our results suggest that the application of the methodology increases peak energy savings up to 17%, scales up solar generation usage up to 23%, and the optimal storage size obtained in the shared community case reduces up to 50%.}, journal={APPLIED ENERGY}, author={Hafiz, Faeza and Queiroz, Anderson Rodrigo and Fajri, Poria and Husain, Iqbal}, year={2019}, month={Feb}, pages={42–54} } @article{hasan_husain_sozer_husain_muljadi_2019, title={Mechanical Performance of Transverse Flux Machines}, volume={55}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2019.2916392}, abstractNote={This research examines the structural and vibrational characteristics of double-sided flux-concentrating transverse flux machines (TFMs), designed for direct-drive application. Two prototypes of TFM with different stator cores, one with Quasi U-Core and the other with E-Core, have been used for this study. Three-dimensional finite element analysis has been carried out to determine the no-load and with-load performances of the TFMs along with their fluctuating axial electromagnetic force densities acting on the stator teeth. The deformation response of the stator cores was observed in the static structural analysis. Acceleration and noise measurements were experimentally obtained to characterize the vibrational performance of the prototypes.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Hasan, Iftekhar and Husain, Tausif and Sozer, Yilmaz and Husain, Iqbal and Muljadi, Eduard}, year={2019}, pages={3716–3724} } @article{islam_mikail_husain_2019, title={Slotless Lightweight Motor for Aerial Applications}, volume={55}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2019.2935055}, abstractNote={A slotless, lightweight permanent-magnet (PM) motor with high pole count is designed and analyzed for a drone system that requires four motors of 0.5 kW each for a 2-kW propulsion power to attain the required torque-speed profile. The design optimization was carried out using finite-element analysis that lead to a slotless stator with outer rotor Halbach PM configuration achieving high power density, zero cogging torque, low torque ripple, sinusoidal back electromotive force, and good system efficiency. The Halbach configuration is found to have superior power density and torque ripple over the conventional concepts for the aerial applications. The power density and efficiency of the slotless motor can be enhanced through the use of nonconventional thermoplastic material and Halbach segmentation. The resulting low inductance of the slotless machine introduces a controls challenge, but it can be overcome with today's enabling technology of wide bandgap devices. A comprehensive analysis and comparison of the slotless design with an equivalent slotted-radial version showed the superiority of the former. An optimum slotless design has been prototyped and test results along with analysis are presented.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Islam, Md Sariful and Mikail, Rajib and Husain, Iqbal}, year={2019}, pages={5789–5799} } @article{husain_elrayyah_sozer_husain_2019, title={Unified Control for Switched Reluctance Motor for Wide Speed Operation}, volume={66}, ISSN={["1557-9948"]}, DOI={10.1109/TIE.2018.2849993}, abstractNote={In this paper, a unified controller for switched reluctance motors is proposed for wide speed operations. The proposed controller achieves minimum output torque ripple at low and medium speeds and operates in a single-pulse mode at high speeds. Overlapping regions between the phases are controlled such that direct instantaneous torque control (DITC) and current control (CC) can be implemented simultaneously on different phases. This simplifies the torque sharing during commutation and minimizes torque ripple due to imperfect current tracking and mutual torque. A demagnetization curve concept to demagnetize the phase currents at an optimum angle is introduced to ensure high torque per ampere and single-pulse mode operation. This results in extending low ripple operation to medium speed ranges. The seamless combination of DITC, CC, and the demagnetization curves leads to torque ripple minimization, automatic excitation angle control, and smooth operation over a wide speed range. The effectiveness of the proposed unified controller is verified through simulation and experimental studies.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Husain, Tausif and Elrayyah, Ali and Sozer, Yilmaz and Husain, Iqbal}, year={2019}, month={May}, pages={3401–3411} } @article{hafiz_chen_chen_queiroz_husain_2019, title={Utilising demand response for distribution service restoration to achieve grid resiliency against natural disasters}, volume={13}, ISSN={["1751-8695"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85069476402&partnerID=MN8TOARS}, DOI={10.1049/iet-gtd.2018.6866}, abstractNote={The increased frequency of power outages due to natural disasters in recent years has highlighted the urgency of enhancing distribution grid resilience. The effective distribution service restoration (DSR) is an important measure for a resilient distribution grid. In this work, the authors demonstrate that DSR can be significantly improved by leveraging the flexibility provided by the inclusion of demand response (DR). The authors propose a framework for this by considering integrated control of household-level flexible appliances to vary the load demand at the distribution-grid level to improve DSR. The overall framework of the proposed system is modelled as a three-step method considering three optimization problems to (i) calculate feasible controllable aggregated load range for each bus, (ii) determine candidate buses to perform DR and their target load demand, and (iii) maintain the load level in each house through home energy management during the DSR, considering uncertainties in load and solar generation sequentially. The optimization problems are formulated as linear programming, mixed-integer linear programming, and multistage stochastic programming (solved using the stochastic dual dynamic programming) models. Case studies performed in the IEEE 123-node test feeder show improvements in resilience in terms of energy restored compared to the restoration process without DR.}, number={14}, journal={IET GENERATION TRANSMISSION & DISTRIBUTION}, publisher={Institution of Engineering and Technology (IET)}, author={Hafiz, Faeza and Chen, Bo and Chen, Chen and Queiroz, Anderson Rodrigo and Husain, Iqbal}, year={2019}, month={Jul}, pages={2942–2950} } @article{kabir_husain_2018, title={Application of a Multilayer AC Winding to Design Synchronous Reluctance Motors}, volume={54}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2018.2859033}, abstractNote={This paper presents the design and experimental validation of a synchronous reluctance motor (SynRM) using a multilayer (ML) ac winding that meets the ultra-premium/IE5 class efficiency requirement. Compared to conventional double-layer ac windings, the ML winding yields a more sinusoidal stator magnetomotive force (MMF) with a shorter end-turn length. The ML winding is characterized using an analytical stator MMF model with verification against finite element analysis (FEA). The proposed winding configuration is optimized under a given design benchmark. The multi-barrier rotor design is also optimized based on FEA using a genetic algorithm. The performance of the designed ML-SynRM is compared against a commercial premium efficiency induction motor and a conventionally wound SynRM for the same standard frame and cooling type. Results show significant efficiency gain with SynRM designs, and also, the designed ML-SynRM yields lower torque ripple with an improved power factor compared to the conventional SynRM. The prototype ML-SynRM is built, and its simulation results are experimentally validated against the benchmark including their performances at a thermal steady state.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Kabir, Md Ashfanoor and Husain, Iqbal}, year={2018}, pages={5941–5953} } @article{husain_hasan_sozer_husain_muljadi_2018, title={Design of a Modular E-Core Flux Concentrating Transverse Flux Machine}, volume={54}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2018.2794376}, abstractNote={In this paper, a novel E-Core transverse flux machine (TFM) is proposed. The machine has a double stator-single rotor configuration with flux concentrating ferrite magnets and pole windings across each leg of an E-Core stator. E-Core stators with the proposed flux-concentrating rotor arrangement result in better magnet utilization and higher torque density. The machine also has a modular structure facilitating simpler construction. This paper presents a single phase and a two-phase version of the E-Core machine. Case study for a 1 kW, 400 r/min machine for both the single phase and two-phase TFM is presented.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Husain, Tausif and Hasan, Iftekhar and Sozer, Yilmaz and Husain, Iqbal and Muljadi, Eduard}, year={2018}, pages={2115–2128} } @article{khan_milani_chakrabortty_husain_2018, title={Dynamic Modeling and Feasibility Analysis of a Solid-State Transformer-Based Power Distribution System}, volume={54}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2017.2757450}, abstractNote={This paper presents a comprehensive state-space dynamic model of a future power distribution system for plug-and-play interface of distributed renewable energy resources and distributed energy storage devices. The system, called the future renewable electric energy delivery and management (FREEDM) system, comprises of multiple solid-state transformers (SSTs), and load, generation, and storage connected to each SST in a distributed network. The system allows for high penetration of renewable generation with energy storage at the distribution level. A physics-based 70th-order state-space average model is first developed considering the physical and controller properties of a single-SST FREEDM system along with its distribution components. This fundamental model is then extended to build a multi-SST FREEDM system for feasibility and dynamics behavior analysis of the entire system, which is essential to ensure system power balance. The full average model with multiple SSTs has been incorporated in an IEEE 34 bus distribution testbed for a scaled analysis of the system.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Khan, Md Tanvir Arafat and Milani, Alireza Afiat and Chakrabortty, Aranya and Husain, Iqbal}, year={2018}, pages={551–562} } @article{milani_khan_chakrabortty_husain_2018, title={Equilibrium Point Analysis and Power Sharing Methods for Distribution Systems Driven by Solid-State Transformers}, volume={33}, ISSN={["1558-0679"]}, DOI={10.1109/tpwrs.2017.2720540}, abstractNote={The feasible equilibria of operation of distribution-level power system models interfaced with solid-state transformers (SST) are analyzed and presented through a set of analytical relationships. The active and reactive power balances in the SST are realized through control of power electronic converters with appropriate choices for voltage and current setpoints. These setpoints parameterize the nonlinear model of the SST. Therefore, choosing them appropriately in sync with the generation and load profiles in the system is critical for maintaining a feasible equilibrium. These equilibrium sets are derived by first considering a fundamental physics-based model of a single-SST system, and thereafter, by extending them to systems with multiple SSTs connected to a radial distribution feeder. Power sharing methods are developed by which multiple SSTs can share a given change in load by generating an appropriate set of feasible setpoints for their input stage rectifiers. A control architecture is proposed for executing these load-sharing methods for both instantaneous and predictive load commands. The algorithms are verified by simulations on a representative distribution test system with nine SSTs.}, number={2}, journal={IEEE TRANSACTIONS ON POWER SYSTEMS}, author={Milani, Alireza Afiat and Khan, Md Tanvir Arafat and Chakrabortty, Aranya and Husain, Iqbal}, year={2018}, month={Mar}, pages={1473–1483} } @inproceedings{aberg_moorthy_yang_yu_husain_2018, title={Estimation and minimization of power loop inductance in 135 kW SiC traction inverter}, DOI={10.1109/apec.2018.8341257}, abstractNote={The paper discusses the estimation and minimization of commutation loop inductance for a printed circuit board (PCB) busbar based 135 kW SiC inverter with a 1 kV DC link using finite element analysis (FEA) simulations. For the inductance estimation of the power module (Wolfspeed: HT-3231-R), PCB busbar, and customized interconnects constituting the commutation loop have been modelled accurately in Ansys Q3D Extractor. Based on the simulation results, subsequent modification to the original PCB busbar design has been proposed to lower the loop inductance. FEA simulation results have resulted in an optimized PCB busbar with lower commutation loop inductance, thereby limiting the device voltage spike well below its rated value. Loop inductance results from the Q3D simulation have been validated through double pulse tests (DPT) and the performance improvements achieved therefore have been highlighted.}, booktitle={Thirty-third annual ieee applied power electronics conference and exposition (apec 2018)}, author={Aberg, B. and Moorthy, R. S. K. and Yang, L. and Yu, Wensong and Husain, I.}, year={2018}, pages={1772–1777} } @article{su_gao_husain_2018, title={Model Predictive Control Based Field-Weakening Strategy for Traction EV Used Induction Motor}, volume={54}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2017.2787994}, abstractNote={The field-weakening scheme is generally adopted for traction motors to achieve a wider speed range where the common proportional and integration compensator is needed to regulate the flux-producing current. However, the regulator performance deteriorates due to dc-link voltage disturbances and motor parameter nonlinearities in the different speed regions. To solve this issue, a model predictive control (MPC) based field-weakening algorithm is proposed for a traction electric vehicle using a low-voltage induction motor. The augmented prediction state relationship between stator voltage and flux-producing current is established for motor current control. The steady-state error can be eliminated with an integrator embedded within the augmented equation. The overall closed-loop control is presented where the system eigenvalues are adjusted in real time for various speed regions, and accordingly, the controller performance can be evaluated with the amplitude of the eigenvalues. Moreover, the weight coefficient in the cost function can be adjusted corresponding to speed variation for guaranteed motor control performance. The simulation and experimental results are provided to verify the proposed MPC-based field-weakening algorithm.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Su, Jianyong and Gao, Rui and Husain, Iqbal}, year={2018}, pages={2295–2305} } @article{ahmed_husain_2018, title={Power Factor Improvement of a Transverse Flux Machine With High Torque Density}, volume={54}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2018.2840487}, abstractNote={Design of a transverse flux machine (TFM) with high power factor and high torque density is presented. Detailed analysis and verification of the benefit of TFMs over conventional radial flux machines, in terms of torque production capability, is described. A comprehensive investigation of the ideal torque production capability, power factor, and deviation from ideal cases is explained. Factors contributing to performance degradation are identified and a robust method is proposed to design and improve the machine performance. Simulation and experimental results are provided to validate the innovation and the robustness of the design process.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Ahmed, Adeeb and Husain, Iqbal}, year={2018}, pages={4297–4305} } @article{hafiz_queiroz_husain_2018, title={Solar Generation Storage, and Electric Vehicles in Power Grids}, volume={6}, ISSN={["2325-5897"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85057761435&partnerID=MN8TOARS}, DOI={10.1109/MELE.2018.2871319}, abstractNote={Solar energy is an abundant renewable energy source that is available all around the world every day. Each hour, the solar rays that reach our Earth (if properly converted to electricity and other forms of energy) represent more than the total energy consumption of the entire human race over the course of one year. Wind energy is another important renewable resource available in large amounts every day. These two renewable energy sources are attracting significant investment as countries seek technology cost reductions to aid sustainability.}, number={4}, journal={IEEE ELECTRIFICATION MAGAZINE}, author={Hafiz, Faeza and Queiroz, Anderson Rodrigo and Husain, Iqbal}, year={2018}, month={Dec}, pages={83–90} } @article{peng_song_huang_husain_2017, title={A Medium-Voltage Hybrid DC Circuit Breaker-Part II: Ultrafast Mechanical Switch}, volume={5}, ISSN={["2168-6777"]}, DOI={10.1109/jestpe.2016.2609391}, abstractNote={This paper presents the test results of an ultrafast (less than 2 ms) medium-voltage hybrid dc circuit breaker prototype that consists of three switching devices: a 15-kV silicon carbide (SiC) emitter turn-off thyristor as the main breaker (MB), a fast acting mechanical switch, and a commutating switch (CS) to quickly divert the primary current to the MB for arcless interruption. The hybrid dc circuit breaker prototype can interrupt a circuit in less than 2 ms in dc power systems up to 10 kV, such as in electric ships. The ultrafast operations and extremely low loss can effectively limit the fault current level and switching transients in all medium-voltage systems, and can provide intelligent and fast protection function for smart power distribution and critical loads in a modernized grid. The design considerations of the three switching devices of the hybrid dc circuit breaker are presented. This paper focuses on the ultrafast mechanical switch and the testing of the hybrid dc circuit breaker, while a companion paper addresses the high-voltage solid-state main switch and the low-voltage solid-state CS.}, number={1}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Peng, Chang and Song, Xiaoqing and Huang, Alex Q. and Husain, Iqbal}, year={2017}, month={Mar}, pages={289–296} } @inproceedings{husain_hasan_sozer_husain_muljadi_2017, title={A comprehensive review of permanent magnet transverse flux machines for direct drive applications}, DOI={10.1109/ecce.2017.8095933}, abstractNote={The use of direct drive machines in renewable and industrial applications are increasing at a rapid rate. Transverse flux machines (TFM) are ideally suited for direct drive applications due to their high torque density. In this paper, a comprehensive review of the permanent magnet (PM) TFMs for direct drive applications is presented. The paper introduces TFMs and their operating principle and then reviews the different type of TFMs proposed in the literature. The TFMs are categorized according to the number of stator sides, types of stator cores and magnet arrangement in the rotor. The review covers different design topologies, materials used for manufacturing, structural and thermal analysis, modeling and design optimization and cogging torque minimization in TFMs. The paper also reviews various applications and comparisons for TFMs that have been presented in the literature.}, booktitle={2017 ieee energy conversion congress and exposition (ecce)}, author={Husain, T. and Hasan, I. and Sozer, Y. and Husain, I. and Muljadi, E.}, year={2017}, pages={1255–1262} } @inproceedings{yang_gao_yu_husain_2017, title={A geometrical linearization approach for salient-pole PMSM optimal voltage/current constrained control over whole speed range}, DOI={10.1109/ecce.2017.8095803}, abstractNote={Permanent Magnet Synchronous Machine (PMSM) torque control over a wide speed range is essentially an optimization problem that treats torque error minimization as the objective function with inverter voltage and current as constraints. It is usually time consuming and difficult to solve such optimization problem for closed-form solutions since torque, voltage and current equations are all non-linear in the problem. In this paper, a model linearization based approach is proposed to manage the calculation complexity for such non-linear optimization. By dividing the problem into two sub-optimizations and solving them sequentially, the calculation is simplified. By identifying different operating regions of the PMSM, the closed-form solutions can be obtained geometrically with model linearization, which further simplifies the optimization process. The proposed algorithm is implemented for PMSM current loop controller design; simulation results show a good performance of the controller.}, booktitle={2017 ieee energy conversion congress and exposition (ecce)}, author={Yang, L. and Gao, R. and Yu, Wensong and Husain, I.}, year={2017}, pages={350–356} } @article{peng_mackey_husain_huang_yu_lequesne_briggs_2017, title={Active Damping of Ultrafast Mechanical Switches for Hybrid AC and DC Circuit Breakers}, volume={53}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2017.2740830}, abstractNote={An active damping method for Thomson coil actuated ultrafast mechanical switches is proposed, including its control. Ultrafast mechanical switches are crucial for both dc and ac circuit breakers that require fast-acting current-limiting capabilities. However, fast motion means high velocity at the end of travel resulting in over-travel, bounce, fatigue, and other undesirable effects. The active damping proposed in this paper not only avoids such issues but actually enables faster travel by removing limitations that would otherwise be necessary. This active damping mechanism is applicable in particular to medium- and high-voltage circuit breakers, but can be extended to actuators in general. A 15 kV/630 A/1 ms mechanical switch designed to enable the fast protection of medium voltage dc circuits is used as a testbed for the concept. The switch is based on the principle of repulsion forces (Thomson coil actuator). By energizing a second coil, higher opening speeds can be damped, resulting in limited over-travel range of the movable contact. The overall structure is simple and the size of the overall switch is minimized. To validate the concept and to study the timing control for best active damping performance, both finite element modeling and experimental studies have been carried out.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Peng, Chang and Mackey, Landon and Husain, Iqbal and Huang, Alex Q. and Yu, Wensong and Lequesne, Bruno and Briggs, Roger}, year={2017}, pages={5354–5364} } @inproceedings{hasan_husain_sozer_husain_muljadi_2017, title={Analytical modeling of a double-sided flux concentrating E-core transverse flux machine with pole windings}, DOI={10.1109/iemdc.2017.8002348}, abstractNote={In this paper, a nonlinear analytical model based on the Magnetic Equivalent Circuit (MEC) method is developed for a double-sided E-Core Transverse Flux Machine (TFM). The proposed TFM has a cylindrical rotor, sandwiched between E-core stators on both sides. Ferrite magnets are used in the rotor with flux concentrating design to attain high airgap flux density, better magnet utilization, and higher torque density. The MEC model was developed using a series-parallel combination of flux tubes to estimate the reluctance network for different parts of the machine including air gaps, permanent magnets, and the stator and rotor ferromagnetic materials, in a two-dimensional (2-D) frame. An iterative Gauss-Siedel method is integrated with the MEC model to capture the effects of magnetic saturation. A single phase, 1 kW, 400 rpm E-Core TFM is analytically modeled and its results for flux linkage, no-load EMF, and generated torque, are verified with Finite Element Analysis (FEA). The analytical model significantly reduces the computation time while estimating results with less than 10 percent error.}, booktitle={2017 IEEE International Electric Machines and Drives Conference (IEMDC)}, author={Hasan, I. and Husain, T. and Sozer, Y. and Husain, I. and Muljadi, E.}, year={2017} } @article{khan_norris_chattopadhyay_husain_bhattacharya_2017, title={Autoinspection and Permitting With a PV Utility Interface (PUI) for Residential Plug-and-Play Solar Photovoltaic Unit}, volume={53}, ISSN={["1939-9367"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85018514651&partnerID=MN8TOARS}, DOI={10.1109/tia.2016.2631135}, abstractNote={Renewable energy resources are becoming popular with mass adoption in residential and commercial applications because of gradual cost reduction along with continuous technical advancements. Photovoltaic (PV) energy is one of the biggest players of renewable energy installations although soft costs remain as the major barrier for higher penetration of PV systems. To address the cost challenges, a plug-and-play (PnP) system for a quick, low-cost installation is proposed and designed. The method is much less invasive and labor intensive than the traditional installation methods. This paper presents the PnP electrical system, with emphasis on the controls, software, and system-level communications within the system. A PV utility interface circuit has been developed for automated electrical safety checks and authentication for the PnP PV system. A data protocol has been used to deal with the master-slave controller setup in the system. This research has the potential to reduce the residential PV system price by $0.6/W.}, number={2}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Khan, Md Tanvir Arafat and Norris, Gregory and Chattopadhyay, Ritwik and Husain, Iqbal and Bhattacharya, Subhashish}, year={2017}, pages={1337–1346} } @article{husain_sozer_husain_2017, title={DC-Assisted Bipolar Switched Reluctance Machine}, volume={53}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2017.2675363}, abstractNote={In this paper, a sinusoidal excited four-phase switched reluctance machine (SRM) with modified dc-assisted windings is presented. The proposed four-phase SRM configuration with modified dc windings has a reduced number of controllable phases and power converter devices. The dc winding configuration is modified from its traditional form by taking advantage of the machine's inherent 90° phase shift between adjacent phases to achieve the desired simplification in the drive. Different power electronic converters for the proposed winding configuration have also been investigated. The proposed concepts are then verified through finite element analysis and an experimental prototype.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Husain, Tausif and Sozer, Yilmaz and Husain, Iqbal}, year={2017}, pages={2098–2109} } @inproceedings{kabir_jaffar_wan_husain_2017, title={Design and experimental evaluation of a multilayer AC winding configuration for sinusoidal MMF with shorter end-turn length}, DOI={10.1109/ecce.2017.8096966}, abstractNote={This paper presents the design and characterization of a multilayer AC winding configuration that provides high quality rotating MMF with reduced end-turn length. Harmonics in the airgap MMF have been characterized with standard winding functions and verified using finite element analysis (FEA). The multilayer winding design is optimized for a commercial premium/IE3 efficiency class benchmark machine and a prototype has been built. Performance of the designed motor has been verified with both FEA and experiments. Experimental evaluation under IEEE 112 standard shows that the designed motor can yield higher torque per unit Cu-loss and efficiency compared to its benchmark.}, booktitle={2017 ieee energy conversion congress and exposition (ecce)}, author={Kabir, M. A. and Jaffar, M. Z. M. and Wan, Z. and Husain, I.}, year={2017}, pages={5834–5839} } @inproceedings{wan_husain_2017, title={Design of a flux switching transverse flux machine based on generalized inductance analysis}, DOI={10.1109/iemdc.2017.8002333}, abstractNote={This paper is dedicated to studying the inductance of Transverse Flux Machines (TFMs). The high inductance of TFMs causes low power factor, high armature reaction, high core loss, and core saturation that limits available torque. This paper aims to conduct a quantitative study on various components of TFM inductance through analytical equations and 3-D finite element analysis (FEA) to show the reasons for, and the effects of, TFM's high inductance. The study finds that even though the high inductance and low power factor are unavoidable in TFM because of its unique winding structure, there are design methods to mitigate this issue. Finally, utilizing the proposed methods, a novel flux switching TFM (FS-TFM) is designed that achieves reduced inductance and improved power factor.}, booktitle={2017 IEEE International Electric Machines and Drives Conference (IEMDC)}, author={Wan, Z. and Husain, I.}, year={2017} } @inproceedings{kabir_husain_2017, title={Design of synchronous reluctance motor with multilayer AC winding}, DOI={10.1109/iemdc.2017.8002131}, abstractNote={This paper presents a new synchronous reluctance motor (SynRM) design with multilayer AC winding to take the advantages of shorter end-winding length and lower stator MMF harmonics compared to the conventional distributed winding. The multilayer winding concept is described along with a discussion on the winding configuration selection. A multi-barrier rotor is designed for the SynRM using finite element analysis (FEA) based multidimensional optimization. Machine rated performances are compared with a commercial squirrel cage induction motor (SCIM) and a conventionally wound SynRM. Significant efficiency gains were achieved with SynRMs compared to the benchmark SCIM. Compared to conventional wound SynRM, the designed SynRM with multilayer winding yields higher torque output with the same copper loss, lower torque ripple, and better power factor, thereby improving the overall SynRM performance. A prototype SynRM with multilayer winding has been built and FEA results have been experimentally verified.}, booktitle={2017 IEEE International Electric Machines and Drives Conference (IEMDC)}, author={Kabir, M. A. and Husain, I.}, year={2017} } @inproceedings{wan_husain_2017, title={Design, analysis and prototyping of a flux switching transverse flux machine with ferrite magnets}, DOI={10.1109/ecce.2017.8095929}, abstractNote={This paper presents a novel Flux Switching Transverse Flux Machine (FS-TFM) topology. This new topology is well suited to use low cost ferrite magnets in a flux focusing design to achieve high torque density. An electric scooter traction motor featuring the proposed topology is designed using soft magnetic composites through 3D finite element analysis. Design optimization and analysis are conducted regarding cogging torque, efficiency, power factor, and demagnetization. The designed FS-TFM has extremely low cogging torque, high torque density even with ferrite magnets, and moderate power factor. A prototype motor is under construction to verify the motor performance through experimental evaluation. Benchmark comparison shows the proposed topology is promising for low-cost, direct-drive applications.}, booktitle={2017 ieee energy conversion congress and exposition (ecce)}, author={Wan, Z. and Husain, I.}, year={2017}, pages={1227–1233} } @inproceedings{gao_yang_yu_husain_2017, title={Gate driver design for a high power density EV/HEV traction driveu using silicon carbide MOSFET six-pack power modules}, DOI={10.1109/ecce.2017.8096484}, abstractNote={Targeting the development of a silicon carbide (SiC) inverter for electric vehicle/hybrid electric vehicle (EV/HEV) applications, the design considerations of the gate driver for the adopted SiC metal-oxide-semiconductor field-transistor (MOSFET) power modules are presented. Given the system power density requirement, the gate driver design challenges for the commercial off-the-shelf (COTS) SiC modules are identified, analyzed, and tackled with proposed solutions. To accomplish such design with the constraint of limited layout space, a single chip MAX 13256 (3 mm×3 mm) enabled high frequency link based isolated bias supply structure is proposed for each six-pack module. Moreover, the gate driver design guidelines for module phase-leg parallel operation are introduced with a comparison study confirming the printed circuit board (PCB) layout effectiveness for electromagnetic interference (EMI) mitigation. Experimental validation is conducted on the traction inverter prototype.}, booktitle={2017 ieee energy conversion congress and exposition (ecce)}, author={Gao, R. and Yang, L. and Yu, Wensong and Husain, I.}, year={2017}, pages={2546–2551} } @inproceedings{hasan_husain_sozer_husain_muljadi_2017, title={Mechanical and thermal performance of transverse flux machines}, DOI={10.1109/ecce.2017.8095926}, abstractNote={This research examines the vibration and thermal characteristics of double-sided flux concentrating Transverse Flux Machines (TFM), designed for direct drive application. Two TFM prototypes with different stator cores, one with Quasi U-Core and the other with E-Core, has been used for the study. 3D Finite Element Analysis (FEA) has been carried out to determine the no-load and with load performance of the TFMs along with their fluctuating axial electromagnetic force densities acting on the stator teeth. The deformation response of the stator cores was observed in the static structural analysis. Thermal analysis for the TFM was performed through FEA based on copper and iron losses in the machine to examine the temperature rise in different parts of the machine structure. Acceleration and noise measurements were experimentally obtained to characterize the vibrational performance of the prototypes.}, booktitle={2017 ieee energy conversion congress and exposition (ecce)}, author={Hasan, I. and Husain, T. and Sozer, Y. and Husain, I. and Muljadi, E.}, year={2017}, pages={1205–1211} } @inproceedings{hafiz_de queiroz_husain_2017, title={Multi-stage stochastic optimization for a PV-storage hybrid unit in a household}, volume={2017-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85044105670&partnerID=MN8TOARS}, DOI={10.1109/ias.2017.8101704}, abstractNote={In the face of increasing global energy supply challenges, renewable energy sources provide a cleaner and environmentally friendly energy alternative. To address the intermittency in PV power generation, battery storage can be used to store energy during lower demand periods. This requires the charging and discharging routine of the storage system to be controlled to achieve optimal economic benefits. In this paper, coordinated control between PV component and an accompanying storage unit is presented considering the stochastic nature of PV generation. The stochastic dual dynamic programming (SDDP) algorithm is employed to optimize the charge/discharge profiles with the goal to minimize the overall cost of satisfying the daily household load demand. The PV-storage hybrid unit can jointly contribute in reducing the consumer costs as shown through simulation analysis.}, booktitle={2017 IEEE Industry Applications Society Annual Meeting, IAS 2017}, author={Hafiz, F. and De Queiroz, A.R. and Husain, I.}, year={2017}, pages={1–7} } @inproceedings{mackey_rachi_peng_husain_2017, title={Optimization of a Z-source, ultra-fast mechanically switched, high efficiency DC circuit breaker}, DOI={10.1109/ecce.2017.8096665}, abstractNote={A novel modification of the Z-source circuit breaker topology is presented for low voltage applications. An ultra-fast mechanical switch has been used in place of the solid-state switch (thyristor) in the Z-source circuit breaker to reduce the energy loss utilizing the very low resistance of mechanical contactors. The proposed modification also facilitates bi-directional current flow for distributed energy resource integration and improves ride through capabilities during downstream load transients. Existing Z-source circuit breaker designs utilize an impedance network to create a forced zero current crossing in the event of a fault in commutating thyristor to isolate the fault from source. However, all load current must flow through the thyristor during normal operation resulting in high loss due to on-state voltage drop of the solid-state switch. To validate the concept and develop proper control for this circuit breaker, both simulations and experimental studies have been carried out. The proposed breaker has been modelled in PSCAD for analysis. Additionally, an analytical estimation model of the system dynamics during fault has been developed to validate the simulations. A test circuit rated for 400 V and 20 A has been designed, constructed and tested.}, booktitle={2017 ieee energy conversion congress and exposition (ecce)}, author={Mackey, L. and Rachi, M. R. K. and Peng, C. and Husain, I.}, year={2017}, pages={3764–3770} } @inproceedings{jaffar_husain_2017, title={Path permeance based analytical inductance model for IPMSM considering saturation and slot leakage}, DOI={10.1109/iemdc.2017.8002132}, abstractNote={The magnetizing q-axis inductance of an optimally designed interior permanent magnet machine (IPM) exhibits a saturating behavior as the current excitation increases. This research work proposes an analytical method to study this behavior by expressing armature reaction as the product of stator MMF and flux path permeance function. The path permeance is a function of both the lamination geometry and the saturated conditions in steel regions. In slotted IPMs, the stator tooth conducts both the magnetizing flux and slot leakage flux, which superpose with each other to determine the saturation condition. This subsidiary phenomenon is investigated in detail using Ampere's law and flux continuity law. Two models are developed and applied to IPMs with single layer and double layer rotor topologies. The results are validated with FEA and a single variable optimization of slot dimensions is illustrated.}, booktitle={2017 IEEE International Electric Machines and Drives Conference (IEMDC)}, author={Jaffar, M. Z. M. and Husain, I.}, year={2017} } @inproceedings{ahmed_husain_2017, title={Power factor improvement of a transverse flux machine with high torque density}, DOI={10.1109/iemdc.2017.8002298}, abstractNote={Design of a permanent magnet transverse flux machine optimized for high torque density and high power factor is presented. The optimization process focuses on performance enhancement through improvement of power factor without sacrificing torque density. Simple magnetostatic simulation based method is proposed for the optimization process. Magnetic couplings among axially separated phases are also discussed in the article. Experimental results demonstrating the correlation of measured inductances with that of simulation results are provided.}, booktitle={2017 IEEE International Electric Machines and Drives Conference (IEMDC)}, author={Ahmed, A. and Husain, I.}, year={2017} } @inproceedings{awal_husain_yu_2017, title={Predictive current control for stabilizing power electronics based AC power systems}, DOI={10.1109/ecce.2017.8096792}, abstractNote={Frequency domain passivity theory is used to evaluate harmonic resonance instabilities in a system with multiple grid-tied voltage source converters (VSCs), and subsequently, a stabilizing controller using predictive current control (PCC) method is proposed to prevent such instabilities. The input admittance of VSCs using PCC can achieve passivity almost up to the Nyquist frequency. This research demonstrates that a very simple and easy implementation of PCC can extend the controller delay dependent stability range of converter side current control for VSCs equipped with LCL-filters up to that point. The alternative approaches achieved stability over similar frequency range by combining complicated active damping techniques with proportional-integral or proportional-resonant type controllers. The frequency domain analysis of the proposed PCC based method is validated via simulation and hardware experiments. The controller is experimentally shown to achieve stable operation irrespective of model imperfections.}, booktitle={2017 ieee energy conversion congress and exposition (ecce)}, author={Awal, M. A. and Husain, I. and Yu, Wensong}, year={2017}, pages={4634–4641} } @article{gao_she_husain_huang_2017, title={Solid-State-Transformer-Interfaced Permanent Magnet Wind Turbine Distributed Generation System With Power Management Functions}, volume={53}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2017.2679679}, abstractNote={The higher penetration of wind energy poses increasing demand for grid support and power management functions of a wind energy conversion system (WECS). This paper investigates a medium-voltage solid-state transformer (SST)-interfaced permanent magnet synchronous generator system with integrated active power management and reactive power compensation functions. Specifically, a WECS consisting of wind turbines, SSTs, and dc loads is presented. In addition, a distributed power management algorithm is proposed for a dc network with local wind turbine controls incorporated to achieve a self-contained power-balanced condition without the need for energy storage or communication devices. Scenarios considered include the grid-connected mode, the islanding mode, and the mode transitions. Simulation results are provided to verify the effectiveness of the proposed strategy. Additionally, the concept is experimentally verified using a scaled-down laboratory prototype.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Gao, Rui and She, Xu and Husain, Iqbal and Huang, Alex Q.}, year={2017}, pages={3849–3861} } @inproceedings{alkuhayli_hafiz_husain_2017, title={Volt/VAR control in distribution networks with high penetration of PV considering inverter utilization}, DOI={10.1109/pesgm.2017.8273823}, abstractNote={In this paper, a Volt/Var control strategy in distribution networks with high PV penetration considering inverter thermal model is presented. This strategy considers a central distribution control to schedule active power and reactive power to deal with solar power generation intermittency. The objective is to provide voltage regulation control while solving for optimal power flow to minimize both distribution system losses and inverter losses. A radial distribution feeder with high PV penetration is considered for the analysis. Simulation results verify the effectiveness of the proposed strategy in regulating voltage within limits while allowing optimal reactive power allocation among distributed generation (DG) units to relieve the stress on some inverters especially those at the end of the feeder.}, booktitle={2017 ieee power & energy society general meeting}, author={Alkuhayli, A. and Hafiz, F. and Husain, I.}, year={2017} } @inproceedings{mackey_rachi_peng_husain_2017, title={Z-source circuit breaker utilizing ultra-fast mechanical switch for high efficiency DC circuit protection}, DOI={10.1109/icdcm.2017.8001084}, abstractNote={A novel modification to Z-Source DC circuit breakers has been proposed to reduce power consumption from its predecessor significantly. The power thyristor serves as the means of circuit isolation and voltage blocking in the event of a fault in traditional Z-Source DC circuit breakers. However, Z-Source circuit breakers direct full load current through the Thyristor. The resulting voltage difference and current flow yield substantial power consumption, heat generation, and reduced efficiency. Integrating a fast-mechanical switch and associated control, a zero current crossing and circuit isolation is achieved without significant on-state switch losses.}, booktitle={2017 IEEE Second International Conference on DC Microgrids (ICDCM)}, author={Mackey, L. and Rachi, M. R. K. and Peng, C. and Husain, I.}, year={2017}, pages={452–458} } @article{peng_husain_huang_lequesne_briggs_2016, title={A Fast Mechanical Switch for Medium-Voltage Hybrid DC and AC Circuit Breakers}, volume={52}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2016.2539122}, abstractNote={This paper presents the design and experimental results of a Thomson coil-based fast mechanical switch for hybrid ac and dc circuit breakers rated at 30-kV voltage and 630-A current. The compact design with optimized circuit parameters and geometric dimensions of components targets 2-mm travel within 1 ms when driven by a 2-mF capacitor bank precharged to 500 V. The use and design of a disc spring as the damping and holding mechanism is presented. Structural design of a complete switch assembly rather than just the actuator is given. Experimental results show that the switch can travel 1.3 mm in the first 1 ms and 3.1 mm in the first 2 ms when driven by a 360-V 2-mF capacitor bank. Such fast mechanical switches facilitate hybrid circuit breaker interruptions within 2 or 3 ms for ultra-fast and highly efficient protections in 5-35 kV medium-voltage dc as well as ac systems.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Peng, Chang and Husain, Iqbal and Huang, Alex Q. and Lequesne, Bruno and Briggs, Roger}, year={2016}, pages={2911–2918} } @inproceedings{peng_mackey_husain_huang_lequesne_briggs_2016, title={Active damping of ultra-fast mechanical switches for hybrid AC and DC circuit breakers}, DOI={10.1109/ecce.2016.7854816}, abstractNote={An active damping method for Thomson coil actuated ultra-fast mechanical switches is proposed, including its control. Ultra fast mechanical switches are crucial for both DC and AC circuit breakers that require fast-acting, current-limiting capabilities. However, fast motion means high velocity at the end of travel, resulting in over-travel, bounce, fatigue, and other undesirable effects. The active damping proposed in this paper not only avoids such issues, but actually enables faster travel by removing limitations that would otherwise be necessary. This active damping mechanism is applicable in particular to medium and high voltage circuit breakers, but can be extended to actuators in general. A 15kV/630A/1ms mechanical switch, designed to enable the fast protection of medium voltage DC circuits, is used as a testbed for the concept. It is based on the principle of repulsion forces (Thomson coil actuator). By energizing a second coil, higher opening speeds can be damped with limited over-travel range of the movable contact. The overall structure is simple, and the size of the overall switch is minimized. To validate the concept and to study the timing control for best active damping performance, both finite element modeling and experimental studies have been carried out.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Peng, C. and Mackey, L. and Husain, I. and Huang, A. and Lequesne, B. and Briggs, R.}, year={2016} } @inproceedings{gao_husain_huang_2016, title={An autonomous power management strategy based on DC bus signaling for solid-state transformer interfaced PMSG wind energy conversion system}, DOI={10.1109/apec.2016.7468353}, abstractNote={The solid-state transformer (SST) enabled DC/AC Microgrid provides an effective solution for distributed renewable energy resources (DRER) integration with conventional utility grid. This paper investigates a DC network system consisting of wind turbines, SST, and DC loads. Without any energy storage devices, an autonomous power management strategy based on improved DC bus signaling (DBS) is proposed to achieve system stable operation and power balance under various scenarios, specifically system grid-connected mode, islanding mode, and the mode transition. The extreme conditions were emphasized and analyzed as a testament to verify the feasibility of proposed control. DC bus voltage level and its gradient information have been employed as the only indication for distinguishing different modes and control implementation. System power management competence has been simulated and verified with MATLAB/Simulink.}, booktitle={Apec 2016 31st annual ieee applied power electronics conference and exposition}, author={Gao, R. and Husain, I. and Huang, A. Q.}, year={2016}, pages={3383–3388} } @inproceedings{hasan_husain_sozer_husain_muljadi_2016, title={Analytical model-based design optimization of a transverse flux machine}, DOI={10.1109/ecce.2016.7854881}, abstractNote={This paper proposes an analytical machine design tool using magnetic equivalent circuit (MEC)-based particle swarm optimization (PSO) for a double-sided, flux-concentrating transverse flux machine (TFM). The magnetic equivalent circuit method is applied to analytically establish the relationship between the design objective and the input variables of prospective TFM designs. This is computationally less intensive and more time efficient than finite element solvers. A PSO algorithm is then used to design a machine with the highest torque density within the specified power range along with some geometric design constraints. The stator pole length, magnet length, and rotor thickness are the variables that define the optimization search space. Finite element analysis (FEA) was carried out to verify the performance of the MEC-PSO optimized machine. The proposed analytical design tool helps save computation time by at least 50% when compared to commercial FEA-based optimization programs, with results found to be in agreement with less than 5% error.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Hasan, I. and Husain, T. and Sozer, Y. and Husain, I. and Muljadi, E.}, year={2016} } @inproceedings{husain_hasan_sozer_husain_muljadi_2016, title={Cogging torque minimization in transverse flux machines}, DOI={10.1109/ecce.2016.7854923}, abstractNote={This paper presents the design considerations in cogging torque minimization in two types of transverse flux machines. The machines have a double stator-single rotor configuration with flux concentrating ferrite magnets. One of the machines has pole windings across each leg of an E-Core stator. Another machine has quasi-U-shaped stator cores and a ring winding. The flux in the stator back iron is transverse in both machines. Different methods of cogging torque minimization are investigated. Key methods of cogging torque minimization are identified and used as design variables for optimization using a design of experiments (DOE) based on the Taguchi method. A three-level DOE is performed to reach an optimum solution with minimum simulations. Finite element analysis is used to study the different effects. Two prototypes are being fabricated for experimental verification.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Husain, T. and Hasan, I. and Sozer, Y. and Husain, I. and Muljadi, E.}, year={2016} } @inproceedings{khan_milani_chakrabortty_husain_2016, title={Comprehensive dynamic modeling of a solid-state transformer based power distribution system}, DOI={10.1109/ecce.2016.7854949}, abstractNote={This paper presents a physics based comprehensive dynamic model of a future power distribution system, termed as the FREEDM system, for plug-and-play interface of distributed renewable energy resources and distributed energy storage devices. The system allows for high penetration of renewable generation with energy storage at the distribution level. FREEDM system consists of an energy router, which is the power electronics based solid-state transformer (SST) that interfaces distributed generation, storage and local loads on the low voltage side with the medium voltage node of the distribution grid. In this paper, state-space modeling and dynamic performance of the SST is analyzed along with the renewable generation sources and storage components with the goal of studying the feasible operating points of the FREEDM system. The actual model of the single-SST system amounts to highly complex dynamics with more than hundred state variables. Singular perturbation based model reduction techniques are applied, thereby leading to a 70th order state-space average model suitable for AC and DC energy cell system sizing, stability analysis, and controller design. The analysis with the system model revealed the SST input stage system parameters have the dominant effect on the feasible operation region.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Khan, M. T. A. and Milani, A. A. and Chakrabortty, Aranya and Husain, I.}, year={2016} } @inproceedings{morgan_xu_hopkins_husain_yu_2016, title={Decomposition and electro-physical model creation of the CREE 1200V, 50A 3-Ph SiC module}, url={https://www.lens.org/005-651-099-193-878}, DOI={10.1109/apec.2016.7468163}, abstractNote={The CREE 1200V/50A, 25mΩ 6-Pack SiC MOSFET module (CCS050M12CM2) is decomposed into a full 3D CAD model, and materials identified, for use in electrical circuit and multi-physics simulations. A reverse engineering technique is first developed, outlined, and then demonstrated on the CREE module. The ANSYS Q3D Extractor is applied to the 3D CAD model where electrical, lumped parameter, parasitic circuit elements are determined. The model is also analyzed with a multi-physics simulator to provide in-situ thermal maps of the baseplate surface for application scenarios, e.g. with a thermal interface material and pin fin heat sink to capture the thermal spreading from junction to case. The complete model is made open source and freely distributed for use by the reader.}, note={\urlhttps://ieeexplore.ieee.org/document/7468163 ; \urlhttps://works.bepress.com/kang-peng/10/download/ ; \urlhttps://works.bepress.com/kang-peng/10/}, booktitle={Apec 2016 31st annual ieee applied power electronics conference and exposition}, author={Morgan, A. J. and Xu, Y. and Hopkins, Douglas C and Husain, I. and Yu, W. S.}, year={2016}, pages={2141–2146} } @article{uddin_husain_sozer_husain_2016, title={Design Methodology of a Switched Reluctance Machine for Off-Road Vehicle Applications}, volume={52}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2015.2514283}, abstractNote={This paper presents the design of a switched reluctance machine (SRM) for off-road hybrid electric vehicle applications. SRMs are ideally suited for this application for their low cost, fault tolerance, and reliable operations. A multistage fast design methodology for SRM is presented in this paper. The process aims to determine the best speed at which the SRM would start single-pulse mode operation. This ensures the best efficiencies over the specified operating range. The machine is initially designed at that operating point using analytical design tools and then further optimized through finite-element analysis (FEA). The designed machine has been prototyped and then experimentally tested.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Uddin, Wasi and Husain, Tausif and Sozer, Yilmaz and Husain, Iqbal}, year={2016}, pages={2138–2147} } @inproceedings{husain_hasan_sozer_husain_muljadi_2016, title={Design considerations of a transverse flux machine for direct-drive wind turbine applications}, DOI={10.1109/ecce.2016.7855015}, abstractNote={This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The TFM has a modular structure with quasi-U stator cores and ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating arrangement to achieve high air gap flux density. The design considerations for this TFM with respect to initial sizing, pole number selection, key design ratios, and pole shaping are presented in this paper. Pole number selection is critical in the design process of a TFM because it affects both the torque density and power factor under fixed magnetic and changing electrical loading. Several key design ratios are introduced to facilitate the design procedure. The effect of pole shaping on back-emf and inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis. A prototype is under construction for experimental verification.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Husain, T. and Hasan, I. and Sozer, Y. and Husain, I. and Muljadi, E.}, year={2016} } @inproceedings{rahman_morgans_xu_gao_yu_hopkins_husain_2016, title={Design methodology for a planarized high power density EV/HEV traction drive using SiC power modules}, url={https://www.lens.org/036-754-675-774-950}, DOI={10.1109/ecce.2016.7855018}, abstractNote={This paper provides a methodology for overall system level design of a high-power density inverter to be used for EV/HEV traction drive applications. The system design is guided to accommodate off-the-shelf SiC power modules in a planar architecture that ensures proper electrical, thermal, and mechanical performances. Bi-directional interleaved DC-DC boost structure and a three-phase voltage source inverter (VSI) have been utilized with the primary focus on the size, weight and loss reduction of passive components. A stacked layer approach has been used for a unique PCB-based busbar, ultra-low profile gate driver, and controller board. This holistic design approach results in a highly compact traction drive inverter with power density of 12.1 kW/L that has lower volume and weight compared to the commercially available state-of-the-art power converter systems.}, note={\urlhttps://ieeexplore.ieee.org/document/7855018/}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Rahman, D. and Morgans, A. J. and Xu, Y. and Gao, R. and Yu, W. S. and Hopkins, Douglas C and Husain, I.}, year={2016} } @article{kabir_husain_2016, title={Design of Mutually Coupled Switched Reluctance Motors (MCSRMs) for Extended Speed Applications Using 3-Phase Standard Inverters}, volume={31}, ISSN={["1558-0059"]}, DOI={10.1109/tec.2015.2499086}, abstractNote={Design of a mutually coupled switched reluctance motor (MCSRM) competitive to the third generation interior permanent magnet synchronous motor (IPMSM) of Toyota Prius 2010 is presented. Compared with conventional SRM (CSRM), the proposed machine utilizes the standard six-switch voltage source inverter, which can facilitate the adoption of reluctance machines for traction applications. The structure of the MCSRM has been optimized for 60 kW output power over wide speed range of operation (2768-13500 r/min). Design details to improve machine torque density and to achieve the wide constant power speed range are presented. Performance evaluation under the targeted benchmark shows that the designed MCSRM can attain competitive performance metrics as that of the third generation IPMSM.}, number={2}, journal={IEEE TRANSACTIONS ON ENERGY CONVERSION}, author={Kabir, Md Ashfanoor and Husain, Iqbal}, year={2016}, month={Jun}, pages={436–445} } @inproceedings{xu_husain_west_yu_hopkins_2016, title={Development of an ultra-high density power chip on bus (PCoB) module}, url={https://www.lens.org/092-761-376-063-354}, DOI={10.1109/ecce.2016.7855040}, abstractNote={A traditional power module uses metal clad ceramic (e.g. DBC or DBA) bonded to a baseplate that creates a highly thermally resistive path, and wire bond interconnect that introduces substantial inductance and limits thermal management to single-sided cooling. This paper introduces a Power Chip on Bus (PCoB) power module approach that reduces parasitic inductance through an integrated power interconnect structure. The PCoB maximizes thermal performance by direct attaching power chips to the busbar, integrating the heatsink and busbar as one, and uses a dielectric fluid, such as air, for electrical isolation. This new power module topology features all planar interconnects and double-sided air cooling. Performance evaluations are carried out through comprehensive electrical and multi-physics simulation and thermal testing for a 1200V, 100A rated single-switch PCoB design. Fabrication and assembly processes are included. For the developed double-sided air-cooled module, 0.5°C/w thermal resistance and 8nH power loop parasitic inductance are achieved.}, note={\urlhttp://ieeexplore.ieee.org/document/7855040/}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Xu, Y. and Husain, I. and West, H. and Yu, W. S. and Hopkins, Douglas C}, year={2016} } @inproceedings{peng_huang_husain_lequesne_briggs_2016, title={Drive circuits for ultra-fast and reliable actuation of Thomson coil actuators used in hybrid AC and DC circuit breakers}, DOI={10.1109/apec.2016.7468279}, abstractNote={Thomson coil actuators (also known as repulsion coil actuators) are well suited for vacuum circuit breakers when fast operation is desired such as for hybrid AC and DC circuit breaker applications. This paper presents investigations on how the actuator drive circuit configurations as well as their discharging pulse patterns affect the magnetic force and therefore the acceleration, as well as the mechanical robustness of these actuators. Comprehensive multi-physics finite-element simulations of the Thomson coil actuated fast mechanical switch are carried out to study the operation transients and how to maximize the actuation speed. Different drive circuits are compared: three single switch circuits are evaluated; the pulse pattern of a typical pulse forming network circuit is studied, concerning both actuation speed and maximum stress; a two stage drive circuit is also investigated. A 630 A, 15 kV / 1 ms prototype employing a vacuum interrupter with 6 mm maximum open gap was developed and tested. The total moving mass accelerated by the actuator is about 1.2 kg. The measured results match well with simulated results in the FEA study.}, booktitle={Apec 2016 31st annual ieee applied power electronics conference and exposition}, author={Peng, C. and Huang, A. and Husain, I. and Lequesne, B. and Briggs, R.}, year={2016}, pages={2927–2934} } @article{malik_husain_2016, title={Dynamic and Steady-State 3-D Thermal Design and Investigation of the Rotating Power Electronic IGBT Converter}, volume={4}, ISSN={["2168-6777"]}, DOI={10.1109/jestpe.2016.2539124}, abstractNote={This paper deals with a 3-D development of a thermal model of a power electronic converter mounted on the generator shaft and rotating with it. The dimensions of the heat sink are determined, and the temperature gradients of the converter, its heat sink, and shaft during natural and forced convection are analyzed for variable rotor speeds. It is shown that the chosen sizes of the insulated gate bipolar transistor (IGBT) and the heat sink offer a compact design of the rotating converter, which is sufficient for its mounting in limited space offered by the generator shaft. Furthermore, a transient temperature profile is also presented. In addition, a transient thermal profile of the converter and dimensions of the cooling fan are also calculated. Besides, the analysis of the cooling requirements of the converter during over-currents due to grid faults is also investigated.}, number={2}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Malik, Naveed-ur-Rehman and Husain, Iqbal}, year={2016}, month={Jun}, pages={679–688} } @article{husain_elrayyah_sozer_husain_2016, title={Flux-Weakening Control of Switched Reluctance Machines in Rotating Reference Frame}, volume={52}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2015.2469778}, abstractNote={A flux-weakening control for switched reluctance motors (SRMs) in the rotating reference frame is proposed in this paper. This rotating reference frame control of SRM mimics the control of synchronous machines (SMs). The method uses the periodic nature of the quasi-sinusoidal static torque characteristics to establish the rotating reference frame. A novel negativity removal block and a simplified nonlinearity handling block are introduced to ensure a smooth torque sharing among different phases and adjust for the SRMs unique operating principle. In the dq control method, a d-axis current is commanded for weakening the flux. An adaptive control method that uses the commanded and actual currents determines the required amount of flux weakening. Through the unique features of dq controls, the proposed method offers smooth torque at low speed and supports a wide-speed operation. The proposed control method is verified experimentally.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Husain, Tausif and Elrayyah, Ali and Sozer, Yilmaz and Husain, Iqbal}, year={2016}, pages={267–277} } @inproceedings{hafiz_fajri_husain_2016, title={Load regulation of a smart household with PV-storage and electric vehicle by dynamic programming successive algorithm technique}, DOI={10.1109/pesgm.2016.7741717}, abstractNote={With increasing concerns on gasoline demand and for a cleaner environment, plug-in hybrid electric vehicles (PHEVs) and zero emission electric vehicles (EVs) have recently received great attention. However, the integration of these vehicles into the power grid has a significant impact on the household load profile. In this paper, load leveling of a residential household by means of coordinated control between solar PV system storage and vehicle battery storage is discussed. Dynamic programming successive algorithm (DPSA) is employed to obtain the optimal charging strategies by minimizing the overall load variance of daily household load demand. The PHEV battery and PV system energy storage can be charged during low demand and the stored power can provide power during high demand period. Thus, both energy storage systems can participate effectively in balancing the demand of the consumer. The simulation results show that the proposed optimal charging strategy reduces the load variance compared to uncontrolled cases of smart household.}, booktitle={2016 ieee power and energy society general meeting (pesgm)}, author={Hafiz, F. and Fajri, P. and Husain, I.}, year={2016} } @inproceedings{su_gao_husain_2016, title={Model predictive control based field-weakening strategy for traction EV used induction motor}, DOI={10.1109/ecce.2016.7855249}, abstractNote={In typical traction Electric Vehicle applications, the DC-link voltage varies during transient accelerating and decelerating process in field-weakening region. The calculated reference voltages of current PI regulators tend to be larger than the one in steady state, which will result in the undesired flux-producing current oscillations. This further deteriorates the electromagnetic torque performance. To solve this issue, a model predictive control (MPC) based field-weakening algorithm is proposed for traction EV used low-voltage induction motor (IM). n this paper, the DC-link voltage utilization, which is usually set as high as possible to output maximum torque, is decreased temporarily to keep the flux-producing current unchanged during the braking process. The model predictive control is adopted for the voltage loop, in which the steady voltage is calculated with steady flux equation. The influence of overlarge voltage calculated from PI regulator is decreased. The simulation and experimental results provide the evidence of improvements of the proposed field-weakening algorithm.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Su, J. Y. and Gao, R. and Husain, I.}, year={2016} } @inproceedings{kabir_husain_2016, title={New multilayer winding configuration for distributed MMF in AC machines with shorter end-turn length}, DOI={10.1109/pesgm.2016.7741756}, abstractNote={New multilayer winding configuration for AC machines is presented that can provide high quality rotating MMF with reduced space harmonics. Compared to the traditional distributed windings the designed winding has shorter end-winding length which will reduce stator I2R loss to improve power conversion efficiency. Unlike the existing fractional-pitch/concentrated winding counterparts, the designed winding provides near sinusoidal airgap MMF which reduces eddy current losses, iron losses and improves power factor. Performance of the designed winding is evaluated for a commercially available premium efficiency induction machine to show that the designed machine attain higher torque density and efficiency compared to the design benchmark. This new winding configuration can be a technology trend in gaining efficiency improvement with low cost non-PM designs under the standard frame sizes.}, booktitle={2016 ieee power and energy society general meeting (pesgm)}, author={Kabir, M. A. and Husain, I.}, year={2016} } @article{cisneros_gao_ortega_husain_2016, title={PI Passivity-Based Control for Maximum Power Extraction of a Wind Energy System with Guaranteed Stability Properties}, volume={17}, ISSN={["1553-779X"]}, DOI={10.1515/ijeeps-2016-0072}, abstractNote={Abstract The present paper proposes a maximum power extraction control for a wind system consisting of a turbine, a permanent magnet synchronous generator, a rectifier, a load and one constant voltage source, which is used to form the DC bus. We propose a linear PI controller, based on passivity, whose stability is guaranteed under practically reasonable assumptions. PI structures are widely accepted in practice as they are easier to tune and simpler than other existing model-based methods. Real switching based simulations have been performed to assess the performance of the proposed controller.}, number={5}, journal={INTERNATIONAL JOURNAL OF EMERGING ELECTRIC POWER SYSTEMS}, author={Cisneros, Rafael and Gao, Rui and Ortega, Romeo and Husain, Iqbal}, year={2016}, month={Oct}, pages={567–573} } @inproceedings{gao_husain_cisneros_ortega_2016, title={Passivity-based and standard PI controls application to wind energy conversion system}, DOI={10.1109/ecce.2016.7855335}, abstractNote={The controller design for wind energy conversion systems (WECS) is complicated considering the highly nonlinear properties of electric machines and power converters. Targeting at a controller for WECS, this article adopts a passivity-based PI control (PI-PBC) method, to which the stability can be analytically guaranteed. Then, a comparative study between the proposed method and a standard PI is provided. The wind energy system consists of a wind turbine, a Permanent Magnet Synchronous Generator (PMSG), a pulse width modulation (PWM) rectifier, a dc load and an equivalent distributed energy storage device, which is formed with a dc source with internal resistor. The generator rotational velocity is regulated at maximum power point (MPPT) for the investigated wind turbine.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Gao, R. and Husain, I. and Cisneros, R. and Ortega, R.}, year={2016} } @inproceedings{kabir_husain_2016, title={Segmented rotor design of concentrated wound switched reluctance motor (SRM) for torque ripple minimization}, DOI={10.1109/ecce.2016.7855420}, abstractNote={Torque ripple minimization of concentrated wound segmented rotor SRM is achieved through rotor segment designs. Compared to existing ripple minimization techniques the proposed method does not require current profiling, controller complexity or additional converter components. First, an FEA based semi-numerical machine model is developed to identify the torque ripple sources. Next, a new design of rotor segment is presented with segmented dip to effectively minimize torque ripple. Effect of different rotor design parameters on machine performance are studied. Both `one factor at a time' and multi-dimensional, multi-objective optimization of design parameters are performed to evaluate their performances. The optimized design can reduce torque ripple by 29% which is a significant improvement considering the simplicity of this method.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Kabir, M. A. and Husain, I.}, year={2016} } @inproceedings{gao_yang_yu_husain_2016, title={Single chip enabled high frequency link based isolated bias supply for silicon carbide MOSFET six-pack power module gate drives}, DOI={10.1109/ecce.2016.7855435}, abstractNote={Regarded as one of the most successful wide bandgap (WBG) devices, Silicon Carbide (SiC) metal-oxide-semiconductor field-transistors (MOSFETs) are being considered in an increasing number of power electronics applications. One of those applications is the hybrid and electric vehicle (HEV/EV) traction inverters where high-efficiency and high-power density is essential. From the system-level perspective, the gate driver circuit design for such device is challenging considering the device's fast switching speed and compact system structure. This paper presents a low profile (6 mm) isolated bias supply design using commercially available components for the SiC MOSFET modules targeting an HEV/EV traction inverter application. A single chip MAX 13256 (3 mm∗3 mm) is adopted to form the high-frequency link for entire power module gate drive supply. Distributed transformer strategy is highlighted to provide multiple isolated output and compact structure with minimized parasitic capacitance between all the isolation barriers. The featured low profile optimization reduces the parasitic parameters that might deteriorate the system performance for the fast switching WBG devices. Moreover, the open-loop high-frequency link architecture allows easy configuration for customized output voltage level, polarity and higher reliability. A prototype gate driver has been built for 1.2 kV, 50 A SiC six-pack MOSFET power module, and experimental results are presented.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Gao, R. and Yang, L. and Yu, Wensong and Husain, I.}, year={2016} } @inproceedings{kabir_mikail_englebretson_husain_2015, title={3D FEA based squirrel cage rotor model for design tradeoffs and performance analysis}, DOI={10.1109/apec.2015.7104732}, abstractNote={An accurate rotor resistance estimation model of squirrel cage induction motors (SCIMs) is developed in 3D FEA. 2D transient analysis was utilized for excitations in the 3D model to improve its accuracy over previous 2D and analytical methods. Rated and starting performance from the FEA model match with the nominal and locked-rotor performance of a 3-phase, 460 V, 1 hp test machine. A modified ring model has been proposed and machine torque-slip characteristics and nominal performance have been analyzed. The effect of slot opening and 4 classes of SCIM bar geometry have been investigated to analyze their relative performance. Finally, four different ring and bar combinations are suggested, with the modified rotor structure presenting gain in starting and rated performance compared to the test machine. Results present the design tradeoffs and performance analysis, first for a 1 hp SCIM and then extended for a higher power (10 hp) machine.}, booktitle={2015 thirtieth annual ieee applied power electronics conference and exposition (apec 2015)}, author={Kabir, M. A. and Mikail, R. and Englebretson, S. and Husain, I.}, year={2015}, pages={2696–2702} } @article{ofori_husain_sozer_husain_2015, title={A Pulse-Injection-Based Sensorless Position Estimation Method for a Switched Reluctance Machine Over a Wide Speed Range}, volume={51}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2015.2420618}, abstractNote={In this paper, a pulse-injection-based method for determining the rotor position of a switched reluctance motor (SRM) over its entire speed range is presented. In this method, a single high-frequency pulse is injected in an idle phase to determine the rotor position at high speeds. The proposed method estimates the rotor position through analysis of the resultant current after voltage pulse injection. A low-speed sensorless method previously developed based on pulse injection has also been extended to improve robustness against varying operating conditions. The developed pulse injection with varying duty ratios provided uniform sensing thresholds over varying dc bus voltages. The low- and high-speed methods are integrated together to provide a robust wide-speed-range rotor position estimator for SRM.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Ofori, Ernest and Husain, Tausif and Sozer, Yilmaz and Husain, Iqbal}, year={2015}, pages={3867–3876} } @inproceedings{wan_ahmed_husain_muljadi_2015, title={A novel transverse flux machine for vehicle traction aplications}, DOI={10.1109/pesgm.2015.7286494}, abstractNote={A novel transverse flux machine topology for electric vehicle traction application using ferrite magnets is presented in this paper. The proposed transverse flux topology utilizes novel magnet arrangements in the rotor that are similar to Halbacharray to boost flux linkage; on the stator side, cores are alternately arranged around a pair of ring windings in each phase to make use of the entire rotor flux that eliminates end windings. Analytical design considerations and finite element methods are used for an optimized design of a scooter in-wheel motor. Simulation results from Finite Element Analysis (FEA) show the motor achieved comparable torque density to conventional rare-earth permanent magnet machines. This machine is a viable candidate for direct drive applications with low cost and high torque density.}, booktitle={2015 ieee power & energy society general meeting}, author={Wan, Z. and Ahmed, A. and Husain, I. and Muljadi, E.}, year={2015} } @inproceedings{peng_husain_huang_lequesne_briggs_2015, title={A past mechanical switch for medium voltage hybrid DC and AC circuit breakers}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Peng, C. and Husain, I. and Huang, A. and Lequesne, B. and Briggs, R.}, year={2015}, pages={5211–5218} } @inproceedings{hasan_husain_uddin_sozer_husain_muljadi_2015, title={Analytical modeling of a novel transverse flux machine for direct drive wind turbine applications}, DOI={10.1109/ecce.2015.7309965}, abstractNote={This paper presents a nonlinear analytical model of a novel double sided flux concentrating Transverse Flux Machine (TFM) based on the Magnetic Equivalent Circuit (MEC) model. The analytical model uses a series-parallel combination of flux tubes to predict the flux paths through different parts of the machine including air gaps, permanent magnets (PM), stator, and rotor. The two-dimensional MEC model approximates the complex three-dimensional flux paths of the TFM and includes the effects of magnetic saturation. The model is capable of adapting to any geometry which makes it a good alternative for evaluating prospective designs of TFM as compared to finite element solvers which are numerically intensive and require more computation time. A single phase, 1 kW, 400 rpm machine is analytically modeled and its resulting flux distribution, no-load EMF and torque, verified with Finite Element Analysis (FEA). The results are found to be in agreement with less than 5% error, while reducing the computation time by 25 times.}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Hasan, I. and Husain, T. and Uddin, M. W. and Sozer, Y. and Husain, I. and Muljadi, E.}, year={2015}, pages={2161–2168} } @inproceedings{khan_norris_chattopadhyay_husain_bhattacharya_2015, title={Auto-inspection and permitting with a PV Utility Interface (PUI) for residential plug-and-play solar photovoltaic unit}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963549051&partnerID=MN8TOARS}, DOI={10.1109/ecce.2015.7310469}, abstractNote={Renewable energy resources are becoming popular with mass adoption in residential and commercial applications because of gradual cost reduction along with continuous technical advancements. Photovoltaic (PV) energy is one of the biggest players of renewable energy installations although soft costs remain as a major barrier for higher penetration of PV systems. To significantly lower the soft costs related to residential photovoltaic system installations, a Plug-and-Play (PnP) system has been designed which allows for a quick, low-cost installation. The method is much less invasive and labor intensive than traditional installation methods involving drilling holes through walls and installing additional panel boxes within the house. This paper presents the PnP electrical system, with emphasis on the controls, software, and system level communications within the system. A PV Utility Interface (PUI) circuit has been developed for automated electrical safety checks and authentication for implementing the PnP PV system. A data protocol has been used to deal with the master-slave controller setup in the system.}, booktitle={2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015}, author={Khan, M.T.A. and Norris, G. and Chattopadhyay, R. and Husain, I. and Bhattacharya, Subhashish}, year={2015}, pages={5763–5770} } @inproceedings{kabir_ahmed_husain_2015, title={Axial flux segmental rotor flux-switching synchronous motor}, DOI={10.1109/ecce.2015.7309963}, abstractNote={A novel three-phase, concentrated winding, axial flux, segmental rotor, flux-switching synchronous motor is presented. The proposed topology has rotor segments made of only iron laminations and operates with flux-switching principle. Compared to existing axial flux permanent magnet (AFPM) topologies, the proposed machine contains reduced amount of permanent magnets located only in its stator. This approach makes the assembly easier and reduce the cost compared to conventional AFPM. Moreover, the proposed topologies have higher torque density and torque-to-weight ratio compared to reported axial flux SRMs (AFSRMs). Detailed design and operation of the proposed machine is presented; the performance of the machine is evaluated for an in-wheel traction application.}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Kabir, M. A. and Ahmed, A. and Husain, I.}, year={2015}, pages={2148–2152} } @article{sikder_husain_ouyang_2015, title={Cogging Torque Reduction in Flux-Switching Permanent-Magnet Machines by Rotor Pole Shaping}, volume={51}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2015.2416238}, abstractNote={Cogging torque in flux-switching permanent-magnet (FSPM) machines is relatively high compared with that of other types of PM machines because of their unique doubly salient structure. Reducing the cogging torque in the FSPM machine is of particular importance to make it a viable alternative to conventional rotor-PM machines. A new pole shaping method has been proposed to reduce the cogging torque. The validity of the proposed method has been confirmed by analytical methods and finite-element-analysis-based simulation. The influence of the proposed pole shaping method on the back-electromotive force (EMF) and average electromagnetic torque has also been investigated.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Sikder, Chandan and Husain, Iqbal and Ouyang, Wen}, year={2015}, pages={3609–3619} } @inproceedings{kabir_husain_2015, title={Concentrated winding segmented rotor switched reluctance machine (SRM) using three-phase standard inverters}, DOI={10.1109/ecce.2015.7310443}, abstractNote={Two new topologies of three-phase segmented rotor switched reluctance machine (SRM) that enables the use of standard voltage source inverters (VSIs) for its operation are presented. The topologies has shorter end-turn length, axial length compared to SRM topologies that use three-phase inverters; compared to the conventional SRM (CSRM), these new topologies has the advantage of shorter flux paths that results in lower core losses. FEA based optimization have been performed for a given design specification. The new concentrated winding segmented SRMs demonstrate competitive performance with three-phase standard inverters compared to CSRM.}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Kabir, M. A. and Husain, I.}, year={2015}, pages={5567–5572} } @inproceedings{husain_sozer_husain_2015, title={DC assisted bipolar switched reluctance machine}, DOI={10.1109/apec.2015.7104360}, abstractNote={In this paper, a sinusoidally excited four-phase switched reluctance machine (SRM) with modified DC assisted windings is presented. The proposed four-phase SRM configuration with modified DC windings has reduced number of controllable phases and power converter devices. The DC winding configuration is modified from its traditional form by taking advantage of the machine's inherent 90 degree phase shift between adjacent phases to achieve the desired simplification in the drive. Different power electronic converters that can be used with the proposed winding configuration have also been investigated. The proposed concepts are then verified through coupled FEA circuit simulations on a case study motor.}, booktitle={2015 thirtieth annual ieee applied power electronics conference and exposition (apec 2015)}, author={Husain, T. and Sozer, Y. and Husain, I.}, year={2015}, pages={254–261} } @inproceedings{husain_sozer_husain_muljadi_2015, title={Design of a modular E-core flux concentrating axial flux machine}, DOI={10.1109/ecce.2015.7310392}, abstractNote={In this paper a novel E-Core axial flux machine is proposed. The machine has a double stator-single rotor configuration with flux concentrating ferrite magnets, and pole windings across each leg of an E-Core stator. E-Core stators with the proposed flux-concentrating rotor arrangement result in better magnet utilization and higher torque density. The machine also has a modular structure facilitating simpler construction. This paper presents a single phase and a three-phase version of the E-Core machine. Case study for a 1.1 kW, 400 rpm machine for both the single phase and three-phase axial flux machine is presented. The results are verified through 3D finite element analysis.}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Husain, T. and Sozer, Y. and Husain, I. and Muljadi, E.}, year={2015}, pages={5203–5210} } @inproceedings{hafiz_fajri_husain_2015, title={Effect of brake power distribution on dynamic programming technique in plug-in series hybrid electric vehicle control strategy}, DOI={10.1109/ecce.2015.7309675}, abstractNote={Plug-in Hybrid Electric Vehicle (PHEV) control strategies have received much attention in recent years for their significant impact in reducing the overall fuel cost. Dynamic programming (DP) is a control method which calculates every possible outcome at each step to find out the optimal supervisory control trajectory. In this work, DP is applied to a PHEV control strategy using a backward looking powertrain model while demonstrating the effect of considering the regenerative braking power distribution. A case study with a Series PHEV model is considered using DP based powertrain control strategy with different drive cycles to demonstrate the importance of considering brake power distribution on the cost-to-go function of these vehicles. The simulation results show that there is significant deviation from the optimal trajectory especially in heavy stop and go traffic situations while brake power distribution is considered.}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Hafiz, F. and Fajri, P. and Husain, I.}, year={2015}, pages={100–105} } @inproceedings{peng_husain_huang_2015, title={Evaluation of design variables in Thompson coil based operating mechanisms for ultra-fast opening in hybrid AC and DC circuit breakers}, DOI={10.1109/apec.2015.7104673}, abstractNote={The paper presents the operation transient analysis and multi-physics complexities in the design of a Thompson coil based ultra-fast mechanical switch for hybrid AC and DC circuit breakers. The electromagnetic, mechanical and thermal behavior of the switch has been analyzed through simulation using a multi-physics finite element software. The design variables have been classified into lumped circuit and geometric parameters; the sensitivity analysis by means of systematic and comprehensive simulations on these parameters helped establish the design guidelines. The switch has been designed with optimization for both the circuit parameters and geometrical dimensions of components targeting 2 mm travel for separation within 1 ms.}, booktitle={2015 thirtieth annual ieee applied power electronics conference and exposition (apec 2015)}, author={Peng, C. and Husain, I. and Huang, A. Q.}, year={2015}, pages={2325–2332} } @article{mikail_husain_islam_sozer_sebastian_2015, title={Four-quadrant torque ripple minimization of switched reluctance machine through current profiling with mitigation of rotor eccentricity problem and sensor errors}, volume={51}, DOI={10.1109/tia.2014.2365715}, abstractNote={This paper presents a method of profiling the phase currents to minimize the torque ripple of switched reluctance machines (SRMs) operating in four-quadrant mode over the entire speed range of operation. The method is based on machine and controller design through coupled simulation of the finite-element-based machine model and the dynamic controller model. The method considers the mutual coupling effect between conducting phases. The research quantifies the effect of sensor error and manufacturing build variations on the level of torque ripple minimization. The mitigation processes to address the issues in mass production are also presented.}, number={3}, journal={IEEE Transactions on Industry Applications}, author={Mikail, R. and Husain, I. and Islam, M. S. and Sozer, Y. and Sebastian, T.}, year={2015}, pages={2097–2104} } @article{sozer_husain_torrey_2015, title={Guidance in Selecting Advanced Control Techniques for Switched Reluctance Machine Drives in Emerging Applications}, volume={51}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2015.2444357}, abstractNote={This paper presents advancements in the control techniques of switched reluctance machines (SRMs) for traction and automotive applications. The high performance of the SRM drive system is embodied in the smooth torque output and high-efficiency control methods in the motoring and generating modes of operation. Wide speed operating ranges for both motoring and generating operations are considered. An SRM designed and built for an off-road traction application is used as an application example. Simulation results for the proposed techniques using an SRM system designed for off-road traction application are presented.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Sozer, Yilmaz and Husain, Iqbal and Torrey, David A.}, year={2015}, pages={4505–4514} } @inproceedings{kabir_husain_2015, title={Hybrid excitation topologies for three-phase mutually coupled reluctance machine with standard inverters}, DOI={10.1109/pesgm.2015.7286004}, abstractNote={New winding configurations for mutually coupled salient pole switched reluctance machines (MCSRMs) have been proposed that enables the application of three-phase standard inverters for variable speed drives. The proposed topologies comprise phase windings carrying balanced three phase currents from standard inverters along with DC excitation coils in the stator slots. Both concentrated and distributed hybrid winding configurations are proposed and performances of these MCSRMs are compared with that of the conventional SRM under the same machine geometry and phase excitation levels. The analysis and results show that the proposed machine configurations with standard inverters are more suitable for low cost, variable speed drives with higher power densities and lower torque ripples compared to conventional SRM drives.}, booktitle={2015 ieee power & energy society general meeting}, author={Kabir, M. A. and Husain, I.}, year={2015} } @article{khan_ahmed_husain_sozer_badawy_2015, title={Performance Analysis of Bidirectional DC-DC Converters for Electric Vehicles}, volume={51}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2015.2388862}, abstractNote={This paper presents the performance analysis and comparison of two types of bidirectional dc-dc converters-cascaded buck-boost capacitor in the middle and cascaded buck-boost inductor in the middle for use in plug-in electric and hybrid electric vehicles. The comparison of the two converters is based on device requirements, rating of switches and components, control strategy, and performance. Each of the converter topologies has some advantages over the other in certain aspects. Efficiency analysis has been carried out for specific scenarios in vehicle applications. The simulation and experimental results are provided for both converter types.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Khan, Mehnaz Akhter and Ahmed, Adeeb and Husain, Iqbal and Sozer, Yilmaz and Badawy, Mohamed}, year={2015}, pages={3442–3452} } @inproceedings{ahmed_wan_husain_2015, title={Permanent magnet transverse flux machine with overlapping stator poles}, DOI={10.1109/ecce.2015.7309770}, abstractNote={A Transverse Flux Machine (TFM) topology with ring winding configuration is proposed. A novel approach for stator pole configuration is presented that ensures lower leakage between adjacent poles. The unique stator pole configuration permits an overlapping region between adjacent stator poles resulting in a significant improvement in space utilization that helps attain higher torque-to-volume ratio. In addition, the innovative pole design reduces the end winding length which helps reduce the copper mass. Simulation results are presented based on 3D Finite Element Analysis (FEA). Significant performance improvement was achieved compared to similar transverse flux machines.}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Ahmed, A. and Wan, Z. and Husain, I.}, year={2015}, pages={791–798} } @inproceedings{safayet_fajri_husain_2015, title={Reactive power management for overvoltage prevention at high PV penetration in low voltage distribution system}, DOI={10.1109/ecce.2015.7309941}, abstractNote={In this paper, a new approach for reactive power management based on inverter's capacity and sensitivity to the critical bus has been presented. The approach addresses the voltage rise and reverse power flow issue when residential renewable energy sources such as rooftop solar panels produce more energy than the local load demand. The overvoltage issues are controlled by active management of reactive power flow. This method improves the voltage regulation of distributed system with high penetration of renewable energy sources while utilizing the inverters' reactive power capacity.}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Safayet, A. and Fajri, P. and Husain, I.}, year={2015}, pages={1988–1994} } @inproceedings{alkuhayli_safayet_husain_2015, title={Single-phase distributed generation synchronization with a distorted or weak grid}, DOI={10.1109/ecce.2015.7309819}, abstractNote={Fast and accurate synchronization of power electronics interfaced distributed generation to the grid or a microgrid is an important step in the management and utilization of the distributed energy resources. Several synchronization algorithms have been proposed to improve the phase tracking of the grid voltage. However, when the grid is weak or distorted, the synchronization process may suffer from poor frequency regulation. Therefore, Sliding Discrete Fourier Transform Phase-locked-loop (SDFT-PLL) algorithm is proposed to extract an accurate angle of the fundamental voltage while rejecting the harmonics in a distorted or weak grid. The SDFT-PLL algorithm and simulation results to validate this method are presented in this paper.}, booktitle={2015 ieee energy conversion congress and exposition (ecce)}, author={Alkuhayli, A. and Safayet, A. and Husain, I.}, year={2015}, pages={1143–1148} } @inproceedings{gao_husain_wang_huang_2015, title={Solid-state transformer interfaced PMSG wind energy conversion system}, DOI={10.1109/apec.2015.7104517}, abstractNote={The solid-state transformer (SST) has been regarded as an emerging technology where emphasis is mainly on the design of the device. To explore its system integration opportunities, this paper proposes and demonstrates a SST interfaced permanent magnet synchronous generator (PMSG) wind energy conversion system. The system integration issues along with wind turbine level control methods have been presented and simulated for power management. Moreover, the lab hardware prototype has been set up, which consists of an induction motor based wind turbine emulator (WTE), PMSG, pulse-width modulation (PWM) rectifier, SST, and resistive load bank. Experiments have been carried out to validate the proposed system and control strategy.}, booktitle={2015 thirtieth annual ieee applied power electronics conference and exposition (apec 2015)}, author={Gao, R. and Husain, I. and Wang, F. and Huang, A. Q.}, year={2015}, pages={1310–1317} } @article{mikail_husain_sozer_islam_sebastian_2014, title={A Fixed Switching Frequency Predictive Current Control Method for Switched Reluctance Machines}, volume={50}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2014.2322144}, abstractNote={The paper presents a novel fixed switching frequency predictive current control method for switched reluctancemachines (SRM). The proposed deadbeat predictive current controller accurately predicts the required duty ratio for thePWM pulse for a given reference current in each digital time step over the entire speed range of operation. The pulsewidth depends on the operating conditions, machine parameters and the rotor position. The controller utilizes themachine inductance profile as a function of current and rotor position to accurately predict the required voltage. Thecontrol method is studied through computer simulation and followed by experimental validation. The method is suitablefor torque ripple sensitive applications requiring accurate tracking of a given current profile and mitigating theaudible noise due to the switching of the inverter.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Mikail, Rajib and Husain, Iqbal and Sozer, Yilmaz and Islam, Mohammad S. and Sebastian, Tomy}, year={2014}, pages={3717–3726} } @article{elrayyah_namburi_sozer_husain_2014, title={An Effective Dithering Method for Electromagnetic Interference (EMI) Reduction in Single-Phase DC/AC Inverters}, volume={29}, ISSN={["1941-0107"]}, DOI={10.1109/tpel.2013.2277665}, abstractNote={A comprehensive method of electromagnetic emission interference (EMI) reduction in dc/ac inverters through periodic dithering of the pulse-width modulated (PWM) switching frequency is presented in this paper. The periodic dithering is the process of changing the switching frequency of the PWM signal that drives the switches of the power electronics inverter. The effects of the various parameters involved in the PWM dithering process have been analyzed in this paper. The important parameters involved in the dithering process are the frequency range used for dithering, the periodic time of the dithering signal, and the phase of the dithering signal. The effect of each of these parameters has been studied to determine their values that minimize the EMI. Additionally, analytical expressions for theoretical prediction of the EMI levels at different frequencies have been derived for performance analysis during the design stage. The theoretical predictions for the dithering signals have been found to accurately correlate with both the simulation and experimental results.}, number={6}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Elrayyah, Ali and Namburi, Krishna M. P. K. and Sozer, Yilmaz and Husain, Iqbal}, year={2014}, month={Jun}, pages={2798–2806} } @article{khan_husain_islam_klass_2014, title={Design of Experiments to Address Manufacturing Tolerances and Process Variations Influencing Cogging Torque and Back EMF in the Mass Production of the Permanent-Magnet Synchronous Motors}, volume={50}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2013.2271473}, abstractNote={A number of manufacturing challenges exist in creating a robust permanent-magnet synchronous motor (PMSM) design to meet critical requirements for cogging torque and torque ripple in specific applications. In addition, reduction of the back electromotive force (BEMF) harmonics that lead to torque ripple is also required during design. Due to manufacturing tolerances, maintaining capability with these requirements is very difficult, particularly for mass production of units. A design of experiments (DOE) that combines manufacturing tolerances with assembly process variations is proposed here to address the sensitivity of cogging torque and harmonics. The limits for the parts and the process variations are extracted from an actual production environment. The DOE is laid out according to one of the robust engineering matrices chosen from Taguchi's method. The DOE results are then utilized to set the tolerance limits for manufacturing the rotor magnets and to set the allowance for the rotor assembly process variations. The method helps to limit the cogging torque and harmonics within predefined bands, thereby producing a robust motor. This paper also investigates the capability of maintaining the tolerances of magnets for a surface-mounted PMSM. The analysis is done using a finite-element method and verified with experimental results.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Khan, Mehnaz Akhter and Husain, Iqbal and Islam, Mohammed Rakib and Klass, Jeffrey T.}, year={2014}, pages={346–355} } @article{elrayyah_safayet_sozer_husain_elbuluk_2014, title={Efficient Harmonic and Phase Estimator for Single-Phase Grid-Connected Renewable Energy Systems}, volume={50}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2013.2266392}, abstractNote={Renewable energy sources (RESs) in any power system can participate in removing the harmonics from the line voltage, but the RESs need to estimate these harmonics first. In this paper, an efficient method to estimate grid harmonics is proposed to be used by single-phase RESs. The proposed method provides accurate estimation for the harmonics while it has lower computation complexity than the other existing methods. To make the harmonic estimation process fast and accurate, the harmonics in the sampled grid voltage is eliminated before passing it to the phase-locked-loop block used for estimating the grid phase. Another application of the proposed method is to transform single-phase voltage or current from the stationary reference frame into the dq rotating reference frame. In this application, the use of the proposed method eliminates the need of generating fictitious voltage or current waveforms orthogonal to the measured quantities. The elimination of need to generate fictitious waveforms speeds up the transformation transients and reduces the operations to less than half of those required by traditional methods. Simulation and experimental results verified that the algorithm achieves fast and accurate harmonic estimation of highly distorted grid voltage.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Elrayyah, Ali and Safayet, Ali and Sozer, Yilmaz and Husain, Iqbal and Elbuluk, Malik}, year={2014}, pages={620–630} } @article{cheng_hu_yang_husain_inoue_krein_lefevre_li_nishi_taiber_et al._2014, title={Electrified Vehicles and the Smart Grid: The ITS Perspective}, volume={15}, ISSN={["1558-0016"]}, DOI={10.1109/tits.2014.2332472}, abstractNote={Vehicle electrification is envisioned to be a significant component of the forthcoming smart grid. In this paper, a smart grid vision of the electric vehicles for the next 30 years and beyond is presented from six perspectives pertinent to intelligent transportation systems: 1) vehicles; 2) infrastructure; 3) travelers; 4) systems, operations, and scenarios; 5) communications; and 6) social, economic, and political.}, number={4}, journal={IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS}, author={Cheng, Xiang and Hu, Xiaoya and Yang, Liuqing and Husain, Iqbal and Inoue, Koichi and Krein, Philip and Lefevre, Russell and Li, Yaoyu and Nishi, Hiroaki and Taiber, Joachim G. and et al.}, year={2014}, month={Aug}, pages={1388–1404} } @inproceedings{kabir_husain_2014, title={Mutually coupled switched reluctance machine (MCSRM) for electric and hybrid vehicles}, DOI={10.1109/pesgm.2014.6939100}, abstractNote={A mutually coupled switched reluctance machine (MCSRM) comparable with interior permanent magnet synchronous machines (IPMSM) and conventional switched reluctance machines (CSRM) have been designed for hybrid electric vehicle (HEV) applications. The MCSRM can utilize the standard six switch inverter. The designed MCSRM is capable of wide speed range operation and has power and torque densities comparable to IPMSM and CSRM.}, booktitle={2014 ieee pes general meeting - conference & exposition}, author={Kabir, M. A. and Husain, I.}, year={2014} } @article{badawy_yilmaz_sozer_husain_2014, title={Parallel Power Processing Topology for Solar PV Applications}, volume={50}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2013.2277546}, abstractNote={An efficient converter topology for extracting maximum power from a photovoltaic module is presented in this paper. The proposed topology is implemented on a stand-alone battery charging system. A reversed buck-boost converter enabling parallel power processing (PPP) with a power switch referenced to the common return is the core of the charging system. Small-signal analysis of the proposed charging system is carried out to facilitate the design of a compensator for maximum power point (MPP) tracking. The simulation and experimental results confirm the validity of the model and verify the high efficient operation while tracking the MPP. The use of the PPP with split loads is also presented which would improve the converter size, efficiency, and step-down duty ratio.}, number={2}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Badawy, Mohamed O. and Yilmaz, Ahmet S. and Sozer, Yilmaz and Husain, Iqbal}, year={2014}, pages={1245–1255} } @article{sikder_husain_sozer_2014, title={Switched Reluctance Generator Control for Optimal Power Generation With Current Regulation}, volume={50}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2013.2270971}, abstractNote={This paper presents a novel method of controlling switched reluctance generators (SRGs) for maximum efficiency with active current regulation. The effect of varying the input control parameters on the efficiency of the SRG is first analyzed through exhaustive data collection through simulation and experiments. The analysis of the collected data showed that the input control parameters that minimize the dc-link current ripple also maximize the generating efficiency. A novel control strategy based on the analysis is then developed to maximize the efficiency indirectly through the control parameters that minimize the dc-link current ripple in real time while delivering the commanded generation power. The controller algorithm has been implemented with a 1-kW experimental three-phase SRG drive system charging a NiMH battery pack.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Sikder, Chandan and Husain, Iqbal and Sozer, Yilmaz}, year={2014}, pages={307–316} } @article{yarlagadda_hartley_husain_2013, title={A Battery Management System Using an Active Charge Equalization Technique Based on a DC/DC Converter Topology}, volume={49}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2013.2264794}, abstractNote={An active charge equalization technique based on a dc/dc converter topology is proposed in this paper. The technique achieves cell balancing of batteries in a stack in terms of both voltage and charge as the pack is being charged/discharged and in idle periods to maximize the energy and reliability of stack operation. A set of MOSFET switches controlled by a voltage monitoring circuit ensures that each battery module has the same output voltage by transferring charge from an individual battery module with the highest voltage to a weak module. An overvoltage and overdischarge protection circuit is presented to reduce the degradation of battery life and to operate each battery within the voltage limits.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Yarlagadda, Sriram and Hartley, Tom T. and Husain, Iqbal}, year={2013}, pages={2720–2729} } @inproceedings{sikder_husain_ouyang_2013, title={Cogging torque reduction in flux-switching permanent magnet machines by rotor pole shaping}, DOI={10.1109/ecce.2013.6646890}, abstractNote={Cogging torque in flux-switching permanent magnet machines (FSPMs) is relatively high compared with other types of PM machines because of their unique doubly salient structure. Reducing the cogging torque in the FSPM machine is of particular importance to make it a viable alternative to conventional rotor-PM machines. A new pole shaping method has been proposed to reduce the cogging torque. The validity of the proposed method has been confirmed by analytical methods and finite element analysis based simulation. The influence of the proposed pole shaping method on the back-EMF and average electromagnetic torque have also been investigated.}, booktitle={2013 ieee energy conversion congress and exposition (ecce)}, author={Sikder, C. and Husain, I. and Ouyang, W.}, year={2013}, pages={1555–1562} } @inproceedings{mikail_husain_islam_2013, title={Finite element based analytical model for controller development of switched reluctance machines}, DOI={10.1109/ecce.2013.6646801}, abstractNote={This paper presents a novel method of modeling SRM including mutual coupling effect based on Finite Element Analysis (FEA). Once the machine geometry and design is completed in FEA, it is required to analyze the performance of the machine at different operating conditions with different control methods. Designing control algorithm with FEA in the loop is not convenient because of the complexity and simulation time involved. An analytical model performing similar to the FEA model and including the mutual coupling effect is desired variable speeds of operation. The self and mutual λ-i-θ during tuning of the control algorithm at different modes and characteristics of the machine can be derived from the FEA on the λ-i-θ characteristics of the machine is developed which can model and stored in a look-up table. A state space model based be readily coupled to any controller model. The method incorporates the mutual coupling effect which cannot be neglected for accurate modeling and good controller performance.}, booktitle={2013 ieee energy conversion congress and exposition (ecce)}, author={Mikail, R. and Husain, I. and Islam, M.}, year={2013}, pages={920–925} } @inproceedings{safayet_husain_elrayyah_sozer_2013, title={Grid harmonics and voltage unbalance effect elimination for three-phase PLL grid synchronization algorithm}, DOI={10.1109/ecce.2013.6647133}, abstractNote={The conventional synchronous reference frame phase locked loop (SRF-PLL) works perfectly for synchronization of utility interactive systems with grid that has no imperfections such as harmonics, unbalanced voltage or frequency fluctuation. However, the power grid suffers from these types of imperfections. For large distributed systems such as solar, onshore and offshore wind or wave energy, there is a need for synchronization with the frequency and phase angle of the three-phase grid contaminated with harmonics. For three-phase systems, the other imperfection of the grid that needs to be eliminated before feeding the grid voltage to PLL is the voltage unbalance. The proposed algorithm demonstrates a method to eliminate both the three-phase grid voltage harmonics and unbalance effects to improve the steady state performance of grid synchronization with high bandwidth PLL.}, booktitle={2013 ieee energy conversion congress and exposition (ecce)}, author={Safayet, A. and Husain, I. and Elrayyah, A. and Sozer, Y.}, year={2013}, pages={3299–3304} } @article{khan_husain_sozer_2013, title={Integrated Electric Motor Drive and Power Electronics for Bidirectional Power Flow Between the Electric Vehicle and DC or AC Grid}, volume={28}, ISSN={["1941-0107"]}, DOI={10.1109/tpel.2013.2258471}, abstractNote={This paper presents an integrated traction machine and converter topology that has bidirectional power flow capability between an electric vehicle and the dc or ac supply or grid. The inductances of the traction motor windings are used for bidirectional converter operation to transfer power eliminating the need for extra inductors for the charging and vehicle-to-grid converter operations. These operations are in addition to the vehicle traction mode operation. The electric powertrain system size and weight can be minimized with this approach. The concept has been analyzed with finite-element- coupled simulation with dynamic analysis software. Experimental results are also provided with electric machines. The interleaving technique has been used with the inductors to share the current and reduce the converter switching stresses.}, number={12}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Khan, Mehnaz Akhter and Husain, Iqbal and Sozer, Yilmaz}, year={2013}, month={Dec}, pages={5774–5783} } @inproceedings{safayet_husain_sozer_2013, title={Reactive power scheduler for voltage regulation of distributed energy systems}, DOI={10.1109/ecce.2013.6647092}, abstractNote={A new reactive power scheduler control algorithm for the distributed voltage regulation with PQ inverters is proposed in this research. An elegant approach to achieve voltage regulation in utility grid is proposed through appropriate control of the renewable energy systems. PQ inverter capable of producing the reactive power is used to either achieve local voltage regulation or produce the reactive power commanded from the outer voltage regulator in the upper hierarchy of the grid management system. The proposed PQ scheduler and PQ inverters will work harmoniously in the local substation with minimum communication interface. The proposed control techniques achieve efficient utilization of the PQ inverters with maximum efficiency. The proposed energy network and the control algorithms are modeled at the system level to verify the effectiveness of the proposed system architecture.}, booktitle={2013 ieee energy conversion congress and exposition (ecce)}, author={Safayet, A. and Husain, I. and Sozer, Y.}, year={2013}, pages={2996–3002} } @article{mikail_husain_sozer_islam_sebastian_2013, title={Torque-Ripple Minimization of Switched Reluctance Machines Through Current Profiling}, volume={49}, ISSN={["0093-9994"]}, DOI={10.1109/tia.2013.2252592}, abstractNote={This paper presents a novel method of profiling the phase currents to minimize the torque ripple of a switched reluctance machine. The method is a combination of machine design and control algorithm. The minimization is accomplished in three steps: The first step is to design a machine that has symmetric torque characteristics with an extended flat portion, the second step is to find the required current profile through simulation, and the third step is the fine tuning of the profile. The simulation is done to verify the method through a coupling of the finite-element-based machine model and the Matlab/Simulink-based dynamic controller model. The coupled simulation considers the nonlinearities, electrical loss, magnetic loss, and mutual coupling. Experimental verification validated the torque-ripple minimization procedure.}, number={3}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Mikail, Rajib and Husain, Iqbal and Sozer, Yilmaz and Islam, Mohammad S. and Sebastian, Tomy}, year={2013}, pages={1258–1267} } @inproceedings{mikail_husain_sozer_islam_sebastian_2012, title={A fixed switching frequency predictive current control method for switched reluctance machines}, DOI={10.1109/ecce.2012.6342731}, abstractNote={The paper presents a novel fixed switching frequency predictive current control method for switched reluctance machines (SRM). The proposed deadbeat predictive current controller accurately predicts the required amount of on-time for the PWM pulse for a given reference current in each digital time step over the entire speed range of operation. The required pulse width depends on the operating conditions, machine parameters and the rotor position. The controller utilizes the machine inductance profile as a function of current and rotor position to accurately predict the required voltage. The control method is studied through computer simulation and followed by experimental validation. The method is suitable for torque ripple sensitive applications requiring accurate tracking of a given current profile and mitigating the audible noise due to the switching of the inverter.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Mikail, R. and Husain, I. and Sozer, Y. and Islam, M. and Sebastian, T.}, year={2012}, pages={843–847} } @inproceedings{khan_husain_islam_klass_2012, title={Design of experiments to address manufacturing tolerances and process variation influencing cogging torque and back EMF in the mass production of the permanent magnet synchronous motors}, DOI={10.1109/ecce.2012.6342359}, abstractNote={A number of manufacturing challenges exist in creating a robust permanent magnet synchronous motor (PMSM) design to meet critical requirements for cogging torque and torque ripple in specific applications. In addition, reduction of back EMF harmonics that lead to torque ripple is also required during design. Due to manufacturing tolerances, maintaining capability with these requirements is very difficult especially for mass production of units. A design of experiments (DOE) that combines manufacturing tolerances with assembly process variations is proposed here to address the sensitivity of cogging torque and harmonics. The limits for the parts and the process variations are extracted from an actual production environment. The DOE is laid out according to one of the robust engineering matrices chosen from Taguchi's method. The findings of the DOE are then utilized to set the tolerance limits for manufacturing the rotor magnets and to set the allowance for the rotor assembly process variation. The method helps limit the cogging torque and harmonics within predefined bands and make the motor design robust. This paper also investigates the capability of maintaining the tolerances of magnets for a surface mounted PMSM. The analysis is done using finite-element method and verified with experimental results.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Khan, M. A. and Husain, I. and Islam, R. and Klass, J.}, year={2012}, pages={3032–3039} } @inproceedings{mikail_husain_sozer_islam_sebastian_2012, title={Four-quadrant torque ripple minimization of switched reluctance machine through current profiling with mitigation of rotor eccentricity problem and sensor errors}, DOI={10.1109/ecce.2012.6342732}, abstractNote={The paper presents a method of profiling the phase currents to minimize the torque ripple of switched reluctance machines (SRM) operating in four quadrant mode over the entire speed range of operation. A single quadrant current profiling presented in [1] is extended to be applicable in the four quadrant mode of operation. The method is based on machine and controller design through coupled simulation of the finite element based machine model and the dynamic controller model. The coupled simulation considers the magnetic nonlinearities, electrical and magnetic losses, and mutual coupling. The research quantifies the effect of position sensor error and manufacturing build variations on the level of torque ripple minimization. The mitigation processes to account for those issues in mass production are also presented.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Mikail, R. and Husain, I. and Sozer, Y. and Islam, M. and Sebastian, T.}, year={2012}, pages={838–842} } @inproceedings{khan_husain_sozer_2012, title={Integrated electric motor drive and power electronics for bidirectional power flow between electric vehicle and DC or AC grid}, DOI={10.1109/ecce.2012.6342328}, abstractNote={This paper presents an integrated traction machine and converter topology that has bidirectional power flow capability between an electric vehicle and the DC or AC supply or grid. The inductances of the traction motor windings are used for bi-directional converter operation to transfer power eliminating the need for extra inductors for the charger and vehicle-to-grid (V2G) converter operation. The electric powertrain system size and weight can be minimized with this approach. The concept has been analyzed with finite element coupled simulation with dynamic analysis software. Experimental results are also provided with an electric machine. The interleaving technique has been used with the inductors to share the current and reduce the converter switching stresses. The proposed integrated converter can operate in the traction mode and in the bidirectional power flow mode when energy can be transferred between the vehicle and the DC or single phase AC supply.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Khan, M. A. and Husain, I. and Sozer, Y.}, year={2012}, pages={3403–3410} } @inproceedings{agamloh_husain_safayet_2012, title={Investigation of the electrical system design concept and grid connection of ocean energy devices to an offshore compressed energy storage system}, DOI={10.1109/ecce.2012.6342377}, abstractNote={One of the biggest challenges of ocean wave and wind energy systems is the mitigation of the intermittency effects, in order to allow for their integration into the electric grid. Energy extraction using an ocean based compressed air energy storage system (OCAES) is proposed to enhance the economic dispatch of these energy sources onto the grid. There are land based compressed air energy systems storage systems. The ocean based version is a relatively new concept that is not proven and has not been studied in detail, yet it has significant advantages over the land based systems. The focus of the paper is on the power transmission and grid control utilizing the OCAES. System design concepts are discussed and simulation results are provided.}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Agamloh, E. B. and Husain, I. and Safayet, A.}, year={2012}, pages={2819–2826} } @article{narla_sozer_husain_2012, title={Switched Reluctance Generator Controls for Optimal Power Generation and Battery Charging}, volume={48}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2012.2209850}, abstractNote={This paper presents the control strategy for varying the turn-on and turn-off angles of three-phase switched reluctance generators (SRGs) to maximize the efficiency as well as to reduce the dc-link ripple current resulting from the commutation of the phases at high speeds. The behavior of the commutation angles is analyzed first through the offline measurement of dc-link current and voltage, generator speed, and phase currents. The analysis of the collected data has shown that the commutation angles providing the minimum ripple on the dc-link current achieve the maximum generating efficiencies. A novel control technique, developed based on the finding, achieves the desired generating set point with maximum efficiency and minimum ripple on the charging current. The control algorithm actively searches the turn-off angles to reduce the amount of normalized ripple on the dc-link current, which also ensures the generation with the maximum efficiency. The turn-on angle is controlled through a proportional-integral controller to generate a desired power level. The algorithm is implemented successfully on a 1-kW three-phase SRG charging a NiMH battery pack.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Narla, Sandeep and Sozer, Yilmaz and Husain, Iqbal}, year={2012}, pages={1452–1459} } @article{arafat_palle_sozer_husain_2012, title={Transition Control Strategy Between Standalone and Grid-Connected Operations of Voltage-Source Inverters}, volume={48}, ISSN={["1939-9367"]}, DOI={10.1109/tia.2012.2210013}, abstractNote={This paper proposes a smooth transition control strategy for voltage-source inverters between standalone (SA) and grid-connected (GC) modes of operation. In the GC mode, the amount of power exchanged with the utility grid is controlled by regulating the phase currents. In the SA mode, the load voltage is regulated by the inverter with its phase dictated by the inverter control. The transition between SA and GC operations that will ensure continuous power delivery to the load requires continuation in the phase of the system voltage. The proportional-integral, trapezoidal, sinusoidal, and staircase frequency variation techniques have been analyzed to find the best approach for minimizing the total harmonic distortion (THD). A smooth frequency variation technique has been developed, which provides lower THD on the voltage waveforms compared with the other techniques. The new algorithm has been implemented on a 5-kW single-phase utility interactive inverter having the SA operation capability. The simulation and experimental results show that the proposed technique provides seamless transition between the inverter modes of operation with minimal distortion at the inverter output voltage.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Arafat, Md. Nayeem and Palle, Sreeshailam and Sozer, Yilmaz and Husain, Iqbal}, year={2012}, pages={1516–1525} }