@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{feng_dayerizadeh_lukic_2021, title={A Coupling-Insensitive X-Type IPT System for High Position Tolerance}, volume={68}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2020.3000116}, DOI={10.1109/TIE.2020.3000116}, abstractNote={The output characteristic of an inductive power transfer (IPT) system is highly susceptible to variations in magnetic coupling. In this article, a primary-side X-type compensation topology is proposed to acquire stable output characteristics against a wide range of magnetic coupling without resorting to tight control and coil design. By introducing the concept and derivation principle for the coupling-insensitive compensation topologies, the X-type network is presented to provide self-regulation ability for primary coil current against variable coupling, thereby enabling steady power transfer in a highly dynamic environment. The design considerations for the passive parameters are elaborated, followed by the comparison with regular compensation methods. Owing to its unique structure and design flexibility, the X-type compensation exhibits a stable output characteristic that is beneficial in enhancing the tolerance to position shifts. Moreover, it also features a wide soft-switching range and more flexible design for the output level range than previous topologies. Experimental results show stable power transfer over a coupling factor of 0.14–0.28, where the power fluctuation is less than 20%. The presented method is seen as a potential solution for low power IPT systems, where high mobility is demanded.}, number={8}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Feng, Hao and Dayerizadeh, Alireza and Lukic, Srdjan M.}, year={2021}, month={Aug}, pages={6917–6926} }
 @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{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{dayerizadeh_feng_lukic_2020, title={Dynamic Wireless Charging: Reflexive Field Containment Using Saturable Inductors}, volume={56}, ISSN={["1939-9367"]}, url={https://doi.org/10.1109/TIA.2020.2964215}, DOI={10.1109/TIA.2020.2964215}, abstractNote={In dynamic wireless charging applications, segmented transmitter coils transfer power to a moving receiver coil. This article proposes a method in which the field strength in coupled transmitter coils automatically adjusts based on the position of the receiver. Specifically, a saturable inductor is applied to provide a high uncompensated inductive reactance in the uncoupled condition. By exploiting the reflected reactance as the system approaches the maximum coupled condition, the inductor saturates and the field strength in the coupled transmitter coils automatically increases. The field strength is at its peak when the transmitting and receiving coils reach their maximum coupling and sharply decreases when the receiver is decoupled from the transmitter. Consequently, the difference between the coupled and uncoupled currents in the transmitter coil is maximized, resulting in a near six-fold improvement in field containment performance compared to previously reported findings. This allows for system-level efficient power transfer and compliance with electromagnetic emission standards without complex shielding circuits and auxiliary active position detection approaches. We present the analysis, design criteria of the compensation network, and experimental validation for the proposed method.}, number={2}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Dayerizadeh, Alireza and Feng, Hao and Lukic, Srdjan M.}, year={2020}, pages={1784–1792} }
 @article{chen_yang_li_feng_zhou_he_mai_2020, title={Reconfigurable Topology for IPT System Maintaining Stable Transmission Power Over Large Coupling Variation}, volume={35}, ISSN={["1941-0107"]}, DOI={10.1109/TPEL.2019.2946778}, abstractNote={Coupling variations in inductive power transfer (IPT) systems are almost inevitable, which results in unstable transmission power. In order to withstand the coupling variation for an IPT system with stable transmission power, a new approach based on reconfigurable compensation topology is proposed. The basic principle is to create two transfer power-coupling coefficient (P–k) curves of two compensation topologies. A switch is utilized to alter one topology to the other topology for the IPT system so that the system can operate within the top regions of the P–k curves of the reconfigurable topology. First, the P–k curve of the detuned series–series (SS) topology is elaborated. Then, the reconfigurable topology is proposed based on the equivalent detuned SS topology, and followed by the parameter design method. Finally, a 400-W prototype is built to verify the validity of the proposed approach. With coupling coefficient variation ranging from 0.1 to 0.25, the transmission power fluctuation of the proposed topology is only 5% with efficiency climbing from 85.8% to 91.7%.}, number={5}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Chen, Yang and Yang, Bin and Li, Qiao and Feng, Hao and Zhou, Xiaobing and He, Zhengyou and Mai, Ruikun}, year={2020}, month={May}, pages={4915–4924} }
 @article{tu_feng_srdic_lukic_2019, title={Extreme Fast Charging of Electric Vehicles: A Technology Overview}, volume={5}, ISSN={["2332-7782"]}, DOI={10.1109/TTE.2019.2958709}, abstractNote={With the number of electric vehicles (EVs) on the rise, there is a need for an adequate charging infrastructure to serve these vehicles. The emerging extreme fast-charging (XFC) technology has the potential to provide a refueling experience similar to that of gasoline vehicles. In this article, we review the state-of-the-art EV charging infrastructure and focus on the XFC technology, which will be necessary to support the current and future EV refueling needs. We present the design considerations of the XFC stations and review the typical power electronics converter topologies suitable to deliver XFC. We consider the benefits of using the solid-state transformers (SSTs) in the XFC stations to replace the conventional line-frequency transformers and further provide a comprehensive review of the medium-voltage SST designs for the XFC application.}, number={4}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Tu, Hao and Feng, Hao and Srdic, Srdjan and Lukic, Srdjan}, year={2019}, month={Dec}, pages={861–878} }