@article{pratik_pantic_2024, title={Comprehensive Modeling of a Back-to-Back Diodes-Based Linear Variable Capacitor}, volume={39}, ISSN={["1941-0107"]}, url={https://doi.org/10.1109/TPEL.2023.3335344}, DOI={10.1109/TPEL.2023.3335344}, abstractNote={The parasitic nonlinear capacitance of diodes is well-known in power electronics literature. This manuscript analytically describes how the nonlinear parasitic capacitance of two back-to-back reverse-biased diodes can act as a linear variable capacitor (LVC) when driven from an ac current or voltage source. An LVC is a bipolar symmetric structure whose conduction principle is based on the displacement current flowing through the junction capacitance of diodes, and no biasing circuit is needed. The manuscript analytically describes the LVC capacitance dependence on the circuit (current, voltage, and frequency) and diode parameters. An in-depth current- and voltage-based LVC capacitance modeling is presented, including the harmonic analysis, safe operation boundary, and the impact of parasitics. SPICE simulations were used to verify the proposed modeling methodology, followed by experiments on three LVCs made of Schottky diodes. The nonlinear capacitance of the diodes is first characterized for differential capacitance, and then, derived parameters are used to verify the proposed LVC capacitance model with current sources at 1 and 2 MHz. The proposed framework can be used to design resonant power circuits with the LVC as a passive component. An integrated LVC can be applied in high-frequency power circuits for load impedance transformation and power control.}, number={2}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Pratik, Ujjwal and Pantic, Zeljko}, year={2024}, month={Feb}, pages={2489–2504} }
 @article{akhmetov_pratik_pantic_2023, title={Accuracy Analysis of the LCR Meter-Based Method for C-V Characterization of a Capacitor}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131396}, abstractNote={The capacitance-voltage (C-V) characterization of capacitors and power semiconductor devices (MOSFETs and diodes) is crucial for circuit analysis and loss modeling. This paper discusses an LCR meter-based capacitive coupling method for C-V characterization. It requires an LCR meter and a few inexpensive passive components. However, the unaccounted effects of the parameters, such as blocking capacitance, filtering inductance, parasitic inductance, or power supply impedance can significantly affect the accuracy of the measuring circuit. In this paper, these effects are analyzed, and the expected error is described analytically. Thus, the measuring circuit can be designed using the derived formulas to achieve the targeted accuracy and frequency range. The measuring circuit with the measuring range of 10 kHz-1 MHz with less than 1% error was designed using the derived analytical equations and validated experimentally.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Akhmetov, Zhansen and Pratik, Ujjwal and Pantic, Zeljko}, year={2023}, pages={2481–2488} }
 @article{azad_pratik_tavakoli_pantic_2023, title={Design of Grid-side Power Management for Bidirectional DWPT Chargers on EV Roadways}, ISSN={["2473-7631"]}, DOI={10.1109/ITEC55900.2023.10186936}, abstractNote={Dynamic Wireless Power Transfer (DWPT) entails an inherently transient power profiles from the electric grid. These power profiles, ranging from tens to hundreds of kilowatts, could expose the grid to significant stress, potentially affecting grid stability. This operating scenario occurs irrespective of the grid-to-vehicle (G2V) or vehicle-to-grid (V2G) charging infrastructure on EV roadways. In this paper, bidirectional DWPT system is designed which manages the grid-side transients, significantly reducing the grid peak-power transients for both G2V and V2G charging scenarios. Supercapacitor units are employed on the grid side as power-buffering units. This design does not require additional grid-side converters, and facilitates downsizing grid side power electronics and cable ratings.}, journal={2023 IEEE TRANSPORTATION ELECTRIFICATION CONFERENCE & EXPO, ITEC}, author={Azad, Ahmed and Pratik, Ujjwal and Tavakoli, Reza and Pantic, Zeljko}, year={2023} }
 @article{akhmetov_abdelraziq_pantic_2023, title={Low Conducted-EMI Single-Phase Boost PFC with Sliding Frequency Modulation}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131650}, abstractNote={A boost Power Factor Correction (PFC) circuit is connected between the AC grid and converters to meet Electromagnetic Interference (EMI) and Total Harmonic Distortion (THD) standards. An EMI filter should be utilized at the input of the PFC to attenuate high-frequency noise injected into the grid. This article discusses the low-conducted EM emission boost PFC with Sliding Frequency Modulation (SFM) proposed by Power Integrations. The proposed boost PFC is compared with a conventional boost PFC operated using Constant Frequency Modulation (CFM) at 120 kHz. Both PFCs are rated for the same nominal power (i.e., 300 W) and output voltage (i.e., 383 V). An analytical loss model is also developed to compare the performance of the SFM and CFM PFCs. The analytical findings are verified by means of simulations and experiments.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Akhmetov, Zhansen and Abdelraziq, Muhammad and Pantic, Zeljko}, year={2023}, pages={1784–1789} }
 @article{azad_tavakoli_pratik_pantic_2023, title={Rapid Prototyping of G2V/V2G DWPT Charge-Control and Grid-side Power Management for EV Applications}, ISSN={["2473-7631"]}, DOI={10.1109/ITEC55900.2023.10186929}, abstractNote={Development and testing of the impact of different wireless charging systems on Electric Vehicle(EV) infrastructures involves considerable effort as it requires different types of coil structures embedded in roadways, different types of EVs, and also requires a test-track setup. Moreover, it requires high speed real-time data measurement and communication to/from an in-motion EV which makes it involving coordinating and testing new control algorithms for such applications. To address this issue, a bidirectional wireless charging system model is proposed in a hardware-in-loop environment, which enables rapid control prototyping of such systems from a benchtop setup. The proposed system can emulate Grid-to-Vehicle(G2V) and Vehicle-to-Grid(V2G) charging profiles for stationary and dynamic charging scenarios. As an additional feature, a versatile grid-side power management algorithm is also developed which significantly reduces grid-side power transients resulted from different types of wireless charging profiles.}, journal={2023 IEEE TRANSPORTATION ELECTRIFICATION CONFERENCE & EXPO, ITEC}, author={Azad, Ahmed and Tavakoli, Reza and Pratik, Ujjwal and Pantic, Zeljko}, year={2023} }
 @article{tavakoli_dede_chou_pantic_2022, title={Cost-Efficiency Optimization of Ground Assemblies for Dynamic Wireless Charging of Electric Vehicles}, volume={8}, ISSN={["2332-7782"]}, DOI={10.1109/TTE.2021.3105573}, abstractNote={Dynamic wireless power transfer (DWPT) allows electric vehicles (EVs) to be charged while in motion. However, high cost and efficiency concerns limit the widespread adoption of DWPT. A ground assembly (GA) accounts for most of the system cost since it is implemented on a significant portion of the road. This article proposes a cost-efficiency optimization algorithm to determine the optimum design of a DWPT transmitter (Tx) pad. Elongated rectangular pads are considered a compromise between cost and efficiency. An optimization methodology is put forward to maximize Tx pad efficiency while minimizing GA cost over a selected road. The optimum design allows constant power transfer inside a selected rated power zone while considering EV lateral misalignment as a random variable. Main cost factors are accounted for, including the cost of the pad coil Litz wire and ferrite material and Tx power electronics and compensation network. Particle swarm optimization allowed the number of finite element analysis simulations to be reduced by intelligently selecting test designs. Statistical analysis is applied to understand the impact of different variables on the final design and the interdependence between variables. Additional analyses are conducted to evaluate the impact of different DWPT aspects, including the wire gauge, probability density of the misalignment variable, multilayer coil design, and capacitor cost modeling. The algorithm is used to design a 3.7-kVA Tx pad with respect to the SAE J2954 receiver test stand VA WPT1/Z1. The optimization Pareto fronts illustrate the family of optimum designs, while the chosen 3.7-kVA pad offers the statistical expected value of pad efficiency as 96%, GA per meter cost of $\$ $ 1004, and an optimum pad length of 1.75 m. The 3.7-kVA optimized pad is manufactured and tested for several operating conditions verifying the simulation results.}, number={1}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Tavakoli, Reza and Dede, Ercan M. and Chou, Chungchih and Pantic, Zeljko}, year={2022}, month={Mar}, pages={734–751} }
 @article{pratik_pantic_2022, title={Design of Variable Air-Core Coupled Co-axial Solenoidal Inductors}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9948050}, abstractNote={Variable inductors find their application in many power electronics circuits. This paper discusses the design and prototype of an air-core coupled co-axial solenoidal inductor as a variable inductor. Analytical modeling and FEA simulations are used to design and optimize a coupled solenoidal variable inductor with a maximum inductance of 18.4 µH at 2 MHz. It is observed that the quality factor of a coupled variable inductor is a function of coupling between the inner and outer windings. It is shown that the quality factor of the variable inductor can be increased by 20% by following the proposed optimization. An experimental inductor prototype is built using 3-D printed support and Litz wire. It is observed that the experimental results closely match the simulation ones.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Pratik, Ujjwal and Pantic, Zeljko}, year={2022} }
 @article{tavakoli_shabanian_dede_chou_pantic_2022, title={EV Misalignment Estimation in DWPT Systems Utilizing the Roadside Charging Pads}, volume={8}, ISSN={["2332-7782"]}, DOI={10.1109/TTE.2021.3091969}, abstractNote={This article presents a magnetic field-based method for vehicle misalignment estimation in dynamic wireless power transfer (DWPT) systems. Road-embedded Transmitter (Tx) pads are employed to both charge a moving electric vehicle (EV) and participate in the estimation of the EV lateral and vertical misalignments (VMs). The EV is equipped with a power receiver (Rx) pad and four sensing coils. The proposed system exploits the existing road-embedded pads to generate a magnetic field for misalignment estimation. The sensing coils measure the magnetic field produced by Tx pads. These measurements are uniquely affected by EV lateral and VMs. Misalignments are estimated by analyzing the voltage induced in sensing coils. Six artificial neural networks (ANNs) are employed to calculate misalignment values in real time and report them to the EV control system or the vehicle driver. To demonstrate the system practicality, a 500-W DWPT prototype consisting of two Tx pads is developed and tested. Misalignment estimation is tested in the range [−15, 15] cm laterally and [16.5, 22.5] cm vertically, and the estimation error is identified to be less than 1.9% and 3.8% of the full misalignment ranges, respectively.}, number={1}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Tavakoli, Reza and Shabanian, Tahmoures and Dede, Ercan M. and Chou, Chungchih and Pantic, Zeljko}, year={2022}, month={Mar}, pages={752–766} }
 @article{chenevert_arora_pantic_2022, title={Evaluation of Low Power Wi-Fi Modules in Emulated Ocean Environments}, ISBN={["978-1-6654-6809-1"]}, ISSN={["0197-7385"]}, DOI={10.1109/OCEANS47191.2022.9977125}, abstractNote={The major problem acoustic underwater communication faces is the low data rate due to low signal frequency. By contrast, the Wi-Fi communication protocol offers high throughput, but limited operating range due to the attenuation effect of the sea and ocean medium. However, short-range near-field underwater wireless power transfer systems offer an environment where Wi-Fi communication can be effectively integrated to collect data and deliver instructions to sensors in underwater sensor networks. In this paper, low-power, low-cost off-the-shelf Wi-Fi modules are explored experimentally for four selected parameters for the different distances between units and different water salinities. The results reveal a shorter operating range and stronger dependence on water salinity than reported so far for high-end Wi-Fi modules.}, journal={2022 OCEANS HAMPTON ROADS}, author={Chenevert, Gabriel and Arora, Abhilash and Pantic, Zeljko}, year={2022} }
 @article{namadmalan_tavakoli_goetz_pantic_2022, title={Self-Aligning Capability of IPT Pads for High-Power Wireless EV Charging Stations}, volume={58}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2022.3158636}, abstractNote={This article studies magnetic forces between transmitter (Tx) and receiver (Rx) coils in an inductive power transfer (IPT) system aiming to use those forces to align the coils and, consequently, improve power transfer. Due to its popularity, the analysis is conducted on a series–series compensated IPT system with planar spiral coils. The proposed method utilizes the bifurcation operation mode of the system and unloaded resonating receiver to maximize attractive force between magnetic couplers. Three-dimensional finite-element method simulations indicate that high-power IPT systems can develop enough attractive force to align coils even under nominal current. Regardless of the coil shape, e.g., spiral or Double-D (DD), the attractive forces tend to align the coils. Hence, a smart charging station can be devised based on self-aligning capability. Furthermore, this article proposes a mechanical structure to facilitate the attractive lateral force for the alignment of high power applications, i.e., wireless fast-charging stations. The forces are analyzed, modeled, and simulated for a 100-kW IPT system with an operating frequency of 20 kHz, while the self-aligning capability is experimentally verified on a downscale 11-kW prototype.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Namadmalan, Alireza and Tavakoli, Reza and Goetz, Stefan M. and Pantic, Zeljko}, year={2022}, month={Sep}, pages={5593–5601} }
 @article{ahluwalia_chenevert_pratik_pantic_2022, title={System for Wireless Charging of Battery-Powered Underwater Sensor Networks}, ISBN={["978-1-6654-6809-1"]}, ISSN={["0197-7385"]}, DOI={10.1109/OCEANS47191.2022.9977272}, abstractNote={Battery-powered Underwater Sensor Networks (USNs) can have limited durability owing to their battery life. This paper proposes an energy delivery system for wireless recharging of USNs using a Remotely Operated Vehicle (ROV), which allows us to extend their lifespans and reduce waste. The wireless charging system’s efficiency is maximized using 3-D Finite Element Analysis (FEA) and an analytical loss model to design and optimize the magnetic coupler. We evaluate the proposed method using a prototype and provide experimental results for coils submerged in water at different salinity levels. These results are also compared with coils placed in the air. A detailed analysis of system operation with changes in the surrounding medium is presented. When operated at an output power of 50 W and an output voltage of 15.6 V, the developed prototype works at a best-case efficiency of 90% with coils submerged in a seawater medium.}, journal={2022 OCEANS HAMPTON ROADS}, author={Ahluwalia, Urvi and Chenevert, Gabriel and Pratik, Ujjwal and Pantic, Zeljko}, year={2022} }
 @article{philips_clark_wallace_coopmans_pantic_bodine_2022, title={User-centred design, evaluation, and refinement of a wireless power wheelchair charging system}, volume={17}, ISSN={["1748-3115"]}, DOI={10.1080/17483107.2020.1818135}, abstractNote={Abstract Purpose To enable power wheelchair users with limited mobility to safely and independently charge their wheelchairs. Methods Stakeholders of multiple roles – including potential users, their caregivers, and clinicians with specifically relevant expertise – were engaged in a user-centred design process. Initial informal interviews, focus groups, online surveys, prototype demonstrations, semi-structured interviews, and expert reviews were utilized to guide development and iteratively evaluate prototypes. Results The resulting wireless charging system enables independent charging while also significantly increasing capacity and charging speed. Autonomous positioning and remote control features further address the particular use cases of the target population, and vital features of existing power wheelchairs are retained according to stakeholder input. Pertinent topics emerging from stakeholder input are discussed. Conclusions Careful application of user-centred design principles is essential to the successful development of usable assistive technology devices, particularly for target populations with complex disabilities. The diverse perspectives of all relevant stakeholders must be considered and synthesized to produce a practical and usable solution. Implications for rehabilitation Battery charge is a constant and critical concern for power wheelchair users. Many power wheelchair users cannot independently use and monitor existing chargers. A wireless wheelchair charging system was developed to alleviate this issue. Sustained user engagement is crucial in the effective development of such assistive technology.}, number={7}, journal={DISABILITY AND REHABILITATION-ASSISTIVE TECHNOLOGY}, author={Philips, Gavin R. and Clark, Cecilia and Wallace, Jeffrey and Coopmans, Calvin and Pantic, Zeljko and Bodine, Cathy}, year={2022}, month={Oct}, pages={815–827} }
 @article{pratik_abdelraziq_ahluwalia_akhmetov_chenevert_pantic_2021, title={Design of a Dual-Loop Controller with Two Voltage- Dependent Current Compensators for an LLC-Based Charger}, ISSN={["1093-5142"]}, DOI={10.1109/COMPEL52922.2021.9645959}, abstractNote={A two-stage charger (PFC+LLC) is developed for Power Mobility Device (PMD) charging applications (i.e., power wheelchairs). The LLC topology is selected due to its ability to maintain ZVS operation over a wide range of load variations. This paper discusses the challenges of designing a dual-loop controller for an LLC-based charger with a wide operation region. It proposes modifying the inner current loop to maintain stable operation over a wide input and output range—the proposed internal loop control switches intelligently between two current controllers based on the output voltage level. A 300-W prototype is designed and tested with a resistive load. Moreover, simulation and experimental results are compared to validate the robustness and stability of the proposed controller.}, journal={2021 IEEE 22ND WORKSHOP ON CONTROL AND MODELLING OF POWER ELECTRONICS (COMPEL)}, author={Pratik, Ujjwal and Abdelraziq, Muhammad and Ahluwalia, Urvi and Akhmetov, Zhansen and Chenevert, Gabriel and Pantic, Zeljko}, year={2021} }
 @article{wang_pratik_jovicic_hasan_pantic_2021, title={Dynamic Wireless Charging of Medium Power and Speed Electric Vehicles}, volume={70}, ISSN={["1939-9359"]}, url={https://doi.org/10.1109/TVT.2021.3122366}, DOI={10.1109/TVT.2021.3122366}, abstractNote={For a broad range of industrial, service, and household electric vehicles, dynamic charging is a viable option for energy replenishing that could reduce the size of the onboard energy storage, remove range limitations, and increase operating time. For these systems, timely detection of an approaching vehicle and the detection of strong coupling conditions between transmitter and receiver coils are of prime interest. A novel method is proposed in this article, which utilizes the existing embedded transmitter coil and power electronics modules to establish a precise detection system based on the power footprint of a traveling receiver. Next, a control algorithm is proposed to control charger activation and deactivation time accurately and deliver the required energy during the maximum coupling of the coils. The proposed sigmoid-curve-based control algorithm achieves a robust, speed-independent, smooth transition between two states while providing fast dynamics for aligned and misaligned conditions. Finally, a novel approach to test high-speed dynamic charging in laboratory conditions based on the receiver emulator is developed and used for experimental validation. The vehicle detection and control techniques have been validated through simulations and experimentally on a speed-controlled dynamic charging test station for a wide speed range. The proposed method does not require any additional hardware, sensing devices, or high-speed communication between the vehicle and the charging infrastructure.}, number={12}, journal={IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Wang, Hongjie and Pratik, Ujjwal and Jovicic, Aleksandar and Hasan, Nazmul and Pantic, Zeljko}, year={2021}, month={Dec}, pages={12552–12566} }
 @article{varghese_sealy_gupta_pantic_2021, title={Experimental and Usability Evaluation of Wireless Power Devices Based on the AirFuel Alliance Magnetic Resonance Standard}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487226}, abstractNote={In the domain of consumer magnetic field wireless power transfer, the two major standards available are the AirFuel Alliance Magnetic Resonance standard developed by the AirFuel Alliance (AFA) and the Qi inductive standard developed by the Wireless Power Consortium. The present work evaluates various AFA-based wireless power devices for consumer electronics. The performed tests include determining the area of nominal power and the 3D charging space for a power receiver unit on the power transmitter unit (PTU), the DC-DC efficiency tests, transmitter and receiver unit temperature tests with and without metallic foreign objects, and leakage magnetic flux density tests.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Varghese, Benny J. and Sealy, Ky and Gupta, Sanjay and Pantic, Zeljko}, year={2021}, pages={2586–2592} }
 @article{tavakoli_pratik_dede_chou_pantic_2021, title={Minimizing the Rebar Impact on Power Dissipation in Dynamic Wireless Power Transfer Systems}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487149}, abstractNote={Dynamic wireless charging of Electric Vehicles (EVs) is realized by embedding magnetic transmitter (Tx) pads into concrete roads. However, the surrounding material may affect the performance of the Tx pads. This paper studies the extra power losses caused by the rebar inserted in the reinforced concrete road behind Tx pads. Furthermore, it is investigated and proved that an aluminum shield can reduce losses in the pad - rebar system. By employing 3-D Finite Element Analysis (FEA), the aluminum shield is optimized such that the losses in the rebar, aluminum sheet, and ferrite core are minimized. A 1.75-m long Tx pad is considered when analyzing the performance of the aluminum shield. It is experimentally validated that the aluminum shield can reduce the transmitter side no-load losses by more than 30% in a 3.7-kW system. Finally, using a reference 3.7-kW receiver (Rx) pad, it is demonstrated that the proposed aluminum shield does not impact the mutual inductance between Tx and Rx pads significantly.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Tavakoli, Reza and Pratik, Ujjwal and Dede, Ercan M. and Chou, Chungchih and Pantic, Zeljko}, year={2021}, pages={1599–1603} }
 @misc{teeneti_truscott_beal_pantic_2021, title={Review of Wireless Charging Systems for Autonomous Underwater Vehicles}, volume={46}, ISSN={["1558-1691"]}, DOI={10.1109/JOE.2019.2953015}, abstractNote={Autonomous underwater vehicles (AUVs) are increasingly used for undersea exploration. The endurance of AUVs is limited by the onboard energy storage among which the battery systems dominate. Various underwater recharging methods are employed to increase the AUV range and autonomy. Currently, contact-based underwater recharging utilizes the wet-mate connector technology that requires a high-precision AUV docking, and is prone to electrical safety issues. To overcome these limitations, underwater wireless recharging techniques for AUVs have been explored in recent years. Wireless charging offers a safe and reliable method for autonomous power transfer between a charging station and a vehicle. This article reviews the state-of-the-art inductive wireless power transfer (IWPT) solutions for underwater applications and discusses the engineering challenges of the IWPT system design. Underwater environmental factors, such as seawater conductivity, temperature, pressure, water currents, and biofouling phenomenon, impose constraints on IWPT systems. A comprehensive review of AUV energy storage systems, docking methods, IWPT system control methods, and compensation networks is presented in this article. Based on the main operational and constructional principles, the AUV IWPT systems are categorized as loosely coupled transformers and resonant IWPT systems. Each of the categories is illustrated through their main design principles and implementations reported in the literature so far. Technical challenges, such as integration of IWPT system into an AUV hull, interoperability, alignment and retention issues, docking station sinking and stability, the design of pressure-tolerant charging electronics, data transfer, and the battery operation in the underwater environment are discussed in this article too. The article is concluded with the best practice overview of designing an IWPT system for AUVs.}, number={1}, journal={IEEE JOURNAL OF OCEANIC ENGINEERING}, author={Teeneti, Chakridhar Reddy and Truscott, Tadd T. and Beal, David N. and Pantic, Zeljko}, year={2021}, month={Jan}, pages={68–87} }
 @article{teeneti_pratik_philips_azad_greig_zane_bodine_coopmans_pantic_2021, title={System-Level Approach to Designing a Smart Wireless Charging System for Power Wheelchairs}, volume={57}, ISSN={["1939-9367"]}, url={https://doi.org/10.1109/TIA.2021.3093843}, DOI={10.1109/TIA.2021.3093843}, abstractNote={New technology design and its integration into a social environment in a noninvasive way are recognized as one of the main challenges of the rapidly growing technology world. The design complexity is amplified if the system is intended for a sensitive user category, e.g., persons with disabilities and aging adults. A high percentage of power wheelchairs (PWCs) users rely on caregivers or family members to charge their PWC units. In this article, a design methodology is presented that describes a system-level approach for designing a 1-kW smart wireless charger for PWCs. This article describes how power electronics, communication, automation, software, and internet technologies are integrated to deliver a functional hands-free, free-position PWC charging solution. The proposed solution utilizes a multicoil transmitter pad to achieve a free-positioning feature and dual-side control to regulate the power. The researchers adopted a human-in-the-loop approach to seek feedback from end-users and tailor the final design through multiple generations of prototypes. Moreover, some existing technical solutions regarding pad design and stray field shielding are adapted or advanced to meet the application requirements, and their effectiveness is validated on a 1-kW prototype.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Teeneti, Chakridhar and Pratik, Ujjwal and Philips, Gavin and Azad, Ahmed and Greig, Mark and Zane, Regan and Bodine, Cathy and Coopmans, Calvin and Pantic, Zeljko}, year={2021}, month={Sep}, pages={5128–5144} }
 @article{feng_tavakoli_onar_pantic_2020, title={Advances in High-Power Wireless Charging Systems: Overview and Design Considerations}, volume={6}, ISSN={["2332-7782"]}, DOI={10.1109/TTE.2020.3012543}, abstractNote={Wireless charging systems are foreseen as an effective solution to improve the convenience and safety of conventional conductive chargers. As this technology has matured, recent broad applications of wireless chargers to electrified transportation have indicated a trend toward higher power, power density, modularity, and scalability of designs. In this article, commercial systems and laboratory prototypes are reviewed, focusing mostly on the advances in high-power wireless charging systems. The recent endeavors in magnetic pad designs, compensation networks, power electronics converters, control strategies, and communication protocols are illustrated. Both stationary and dynamic (in-motion) wireless charging systems are discussed, and critical differences in their designs and applications are emphasized. On that basis, the comparisons among different solutions and design considerations are summarized to present the essential elements and technology roadmap that will be necessary to support large-scale deployment of high-power wireless charging systems. The review is concluded with the discussion of several fundamental challenges and prospects of high-power wireless power transfer (WPT) systems. Foreseen challenges include utilization of advanced materials, electric and electromagnetic field measurement and mitigation, customization, communications, power metering, and cybersecurity.}, number={3}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Feng, Hao and Tavakoli, Reza and Onar, Omer C. and Pantic, Zeljko}, year={2020}, pages={886–919} }
 @article{lukic_onar_pantic_2019, title={Guest Editorial Special Issue on High-Power Fast Chargers and Wireless Charging}, volume={5}, ISSN={["2332-7782"]}, DOI={10.1109/TTE.2019.2959159}, abstractNote={Electric transportation systems have made great strides forward in terms of performance and cost-effectiveness. Electric drivetrains provide better efficiency and higher reliability due to the lower complexity and smaller part numbers compared to combustion-based drivetrains. As such, electric transportation concepts are becoming viable for all modes of transportation. This move toward transportation electrification is enabled by the drastic improvements in battery performance, making passenger vehicles with a range of over 200 mi cost-competitive with petroleum-powered vehicles. Despite the increasing number of electric vehicles (EVs) on the roads, the lack of charging infrastructure and long charging times restricts the use of these vehicles for daily commutes and short-distance trips.}, number={4}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Lukic, Srdjan and Onar, Omer and Pantic, Zeljko}, year={2019}, month={Dec}, pages={858–860} }
 @article{lee_pantic_lukic_2014, title={Reflexive Field Containment in Dynamic Inductive Power Transfer Systems}, volume={29}, ISSN={["1941-0107"]}, DOI={10.1109/tpel.2013.2287262}, abstractNote={We present a new topology appropriate for “dynamic” wireless charging. Possible applications include charging of electric vehicles or robots moving in a large, predesignated area. We propose a system with a transmitter made from multiple coils commensurable with the moving receiver(s), and powered by a single inverter. The proposed system uses the reactance reflected by the receiver to automatically increase the field strength in coupled portions of the transmitter-receiver system, thus allowing efficient power transfer and adherence to electromagnetic field emission standards without complex shielding circuits, switches, electronics, and communication. The power transfer is at its peak when the transmitting and receiving coils approach their maximum coupling (as defined by the geometrical constraints of the system), resulting in improved system-level efficiency. The presented analysis is supported with simulations and experiments.}, number={9}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Lee, Kibok and Pantic, Zeljko and Lukic, Srdjan M.}, year={2014}, month={Sep}, pages={4592–4602} }
 @article{pantic_lukic_2013, title={Computationally-Efficient, Generalized Expressions for the Proximity-Effect in Multi-Layer, Multi-Turn Tubular Coils for Wireless Power Transfer Systems}, volume={49}, ISSN={["1941-0069"]}, DOI={10.1109/tmag.2013.2264486}, abstractNote={Wireless power transfer (WPT) based on magnetic induction is used in numerous applications where physical contact between the power source and the load is not desired. For efficient power transfer, the resonant coils should have a low equivalent series resistance at the resonant frequency and have a high packing factor while being simple to manufacture. Coils made from hollow copper tubes might be an acceptable alternative to Litz wire designs due to low skin-effect resistance, easy manufacturing, and simplicity in implementing active cooling; however, the lack of an analytical model for complex coil designs poses a difficulty in systematically assessing its benefits and limitations. This paper presents a new method, based on the Fourier series, for evaluating proximity-effect losses in a multi-turn, multi-layer tubular coil. The model evaluates the proximity factor Gp as a function of coil and tube parameters, which can be incorporated into the design and optimization procedures. The derivations are supported by simulations that compare analytic and finite element models (FEM) of current density distribution in the coil. The model is further validated via experimental measurements of the resulting equivalent series resistance for two prototype coils.}, number={11}, journal={IEEE TRANSACTIONS ON MAGNETICS}, author={Pantic, Zeljko and Lukic, Srdjan}, year={2013}, month={Nov}, pages={5404–5416} }
 @inproceedings{lee_pantic_lukic_2013, title={Field containment in dynamic wireless charging systems through source-reciever interaction}, DOI={10.1109/ecce.2013.6647183}, abstractNote={This paper presents a new topology appropriate for dynamic wireless charging of electric vehicles. We propose a source coil made from multiple lumped coils powered by a single inverter, with the receiver coil mounted on the vehicle. The proposed system uses the reflected reactance from the receiver to automatically limit the field strength in uncoupled portions of the source-receiver system, thus allowing the system to more easily meet the electromagnetic field emission standards without complex shielding circuits, switches, electronics and communication systems. The power transfer is at its peak when the source-receiver coils pair is strongly coupled resulting in improved system-level efficiency. The analysis is supported by simulation and experiments.}, booktitle={2013 ieee energy conversion congress and exposition (ecce)}, author={Lee, K. and Pantic, Z. and Lukic, S.}, year={2013}, pages={3658–3663} }
 @inproceedings{pantic_lee_lukic_2013, title={Inductive power transfer by means of multiple frequencies in the magnetic link}, DOI={10.1109/ecce.2013.6647080}, abstractNote={In this paper we explore the concept of transmitting and receiving power wirelessly at multiple frequencies. This proposed frequency multiplex is achieved by using multi-resonant tanks at the transmitter and receiver to amplify and extract power at multiple frequencies. Frequency multiplexed IPT system is a new concept that has numerous advantages over the state of the art: (1) low switching frequency converters can be used to drive high-frequency IPT systems, (2) emission standards may become easier to meet by spreading the power transfer over a spectrum of frequencies, (3) single-frequency receivers tuned to different frequencies can be charged simultaneously even though their coils are at close proximity and mutually coupled, etc. In this paper we develop the theory of source and receiver resonant tank design, and present the complete methodology for determining the system quality factor, effective resistance and power transfer at each frequency. We present a case study of a system that transfers equal amounts of power at 25 kHz and 75 kHz through simulations and experiments.}, booktitle={2013 ieee energy conversion congress and exposition (ecce)}, author={Pantic, Z. and Lee, K. and Lukic, S.}, year={2013}, pages={2912–2919} }
 @inproceedings{pantic_heacock_lukic_2012, title={Magnetic link optimization for wireless power transfer applications: modeling and experimental validation for resonant tubular coils}, booktitle={2012 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Pantic, Z. and Heacock, B. and Lukic, S.}, year={2012}, pages={3825–3832} }
 @inproceedings{pantic_bai_lukic_2011, title={A new tri-state-boost-based pickup topology for inductive power transfer}, DOI={10.1109/ecce.2011.6064241}, abstractNote={In this paper we present a new circuit design for multi-pickup high-power inductive power transfer systems. The proposed design combines parallel compensated resonant tank with tri-state boost converter. By synchronizing tri-state boost switching period with the half-period of resonant tank voltage, we position the inherently discontinuous current pulse drawn by tri-state boost to control both active and reactive power flow from the resonant circuit to tri-state boost. Controllable reactive current can be used effectively to emulate appropriate inductance or capacitance to tune the resonant tank and achieve optimal power transfer.}, booktitle={2011 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Pantic, Z. and Bai, S. Z. and Lukic, S.}, year={2011}, pages={3495–3502} }
 @article{pantic_bai_lukic_2011, title={ZCS LCC-Compensated Resonant Inverter for Inductive-Power-Transfer Application}, volume={58}, ISSN={["1557-9948"]}, DOI={10.1109/tie.2010.2081954}, abstractNote={Inductive power transfer (IPT) is commonly used to transmit power from an extended loop (track) to a number of galvanically isolated movable pick-ups. To maximize the power transfer and minimize converter requirements, various compensation circuits have been proposed for both the track (primary) and the pick-up (secondary). This paper investigates the suitability of the LCC series-parallel compensation for IPT primary design. A new compensation-circuit design procedure is proposed that considers high-order current harmonics and results in inverter zero-current switching. The proposed compensation is compared with the classical compensation designed for zero phase angle between the inverter voltage and current fundamental components. Expressions for the bifurcation boundary, voltampere rating of reactive-compensation elements, and the current at the moment of switching are derived and analyzed. Analytical results are verified both via PSpice simulations and experimentally using a 1-hp MOSFET-based prototype.}, number={8}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, publisher={IEEE}, author={Pantic, Zeljko and Bai, Sanzhong and Lukic, Srdjan M.}, year={2011}, month={Aug}, pages={3500–3510} }
 @inproceedings{bai_pantic_lukic_2010, title={A comparison study of control strategies for ZVS resonant converters}, DOI={10.1109/iecon.2010.5675019}, abstractNote={This paper studies three fundamental switching patterns for resonant converters to achieve Zero Voltage Switching (ZVS) operation. To evaluate the performance of the three control methods, three resonant topologies are taken into consideration: series resonant, parallel resonant and seriesparallel resonant. The criteria functions for ZVS operation are derived for each control method and topology. The results show that the Asymmetrical Clamped Mode control (ACM) can guarantee lower switching frequency than other two control methods while keeping ZVS operation. Moreover, the circulating power for each control method is analyzed. The relationships between the switching frequency and the maximum power transfer of the three resonant topologies are derived and the series-parallel resonant topology shows a superior characteristic. Experiment results are given to verify some of the results.}, booktitle={Iecon 2010: 36th annual conference of the ieee industrial electronics society}, author={Bai, S. Z. and Pantic, Z. and Lukic, S.}, year={2010} }
 @inproceedings{pantic_bai_lukic_2009, title={Inductively coupled power transfer for continuously powered electric vehicles}, booktitle={2009 ieee vehicle power and propulsion conference, vols 1-3}, author={Pantic, Z. and Bai, S. and Lukic, S. M.}, year={2009}, pages={1097–1104} }