@misc{won_srdic_lukic_2022, title={Optimized Multi-Carrier PWM Strategy and Topology Review for Multi-Cell Series-Parallel Medium-Voltage Rectifier}, volume={10}, ISSN={["2168-6785"]}, DOI={10.1109/JESTPE.2021.3129797}, abstractNote={Solid-state transformer (SST) acting as a medium-voltage (MV) rectifier is a viable solution to supply low-voltage DC (LVDC) loads directly from the MV ac grid. Different from a classical boost-derived power-factor-correction (PFC) topology, the multicell series-parallel (MCSP) converter steps down and distributes the input ac voltage by multiple switching cells while providing the PFC function. We propose an optimized multicarrier pulsewidth modulation (PWM) strategy to avoid unwanted modes by modified multicarrier waveforms for ensuring frequent parallel connectivity to improve balancing effect while preserving simple current control implementation. Compared with conventional phase-shifted (PS) PWM and other modified multilevel carrier methods, the proposed method has no adverse effect on the input current distortion and optimizes the balancing effect on the capacitor voltages resulting suppressed circulating currents. Effectively reduced current stresses on the switch devices could lead a reduction of conduction loss on the device. Topology discussion, circulating currents, digital implementation, and loss analysis are provided. Finally, the superiority of the proposed PWM method is validated by thermal-based simulation presenting a power loss breakdown and comparing with other PWM methods. A full-scale prototype is developed, and the experimental outcomes verify the remarkable performance of proposed PWM scheme in balanced and even suppressed switch currents with improved system efficiency.}, number={6}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Won, Jehyuk and Srdic, Srdjan and Lukic, Srdjan M.}, year={2022}, month={Dec}, pages={6770–6783} }
 @article{won_jalali_liang_zhang_srdic_lukic_2019, title={Auxiliary Power Supply for Medium-Voltage Power Converters: Topology and Control}, volume={55}, ISSN={["1939-9367"]}, DOI={10.1109/TIA.2019.2915511}, abstractNote={This paper presents an isolated auxiliary power supply for medium-voltage power electronics systems. The proposed converter comprises two stages: a non-isolated ac/dc stage that connects directly to the medium-voltage line, and an isolated dc/dc stage that provides 100-W output power at 24 V, with 10 kV isolation. The proposed modular ac/dc stage uses just one active semiconductor device per module, features an internal capacitor voltage balancing, and achieves power factor correction by employing predictive current control. High switching frequency operation of both converter stages enable a reduction in system size and weight when compared to traditional low-frequency transformer-based approach. The proposed converter is simulated and its operation is validated experimentally on a 100-W prototype.}, number={4}, journal={IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS}, author={Won, Jehyuk and Jalali, Gholamreza and Liang, Xinyu and Zhang, Chi and Srdic, Srdjan and Lukic, Srdjan M.}, year={2019}, pages={4145–4156} }
 @inproceedings{won_jalali_liang_zhang_srdic_lukic_2018, title={Auxiliary power supply for medium-voltage power electronics systems}, DOI={10.1109/apec.2018.8341005}, abstractNote={This paper presents an auxiliary power supply for medium-voltage (MV) power electronics systems, based on modular multilevel series-parallel converter (MMSPC). The converter connects to 2.4 kV RMS at the input, and produces 24 V dc at the output, providing 100 W of power with 10 kV isolation. Unlike the traditional solutions which use a grid-frequency bulky and heavy potential transformers, the proposed converter can operate at higher switching frequencies, thus reducing the weight and providing higher power density, compared to the traditional approach. Additionally, the proposed converter features an internal capacitor voltage balancing and achieves power factor correction (PFC) by using predictive control. The proposed converter is simulated and its operation is experimentally validated on the developed prototype at low input voltage.}, booktitle={Thirty-third annual ieee applied power electronics conference and exposition (apec 2018)}, author={Won, J. and Jalali, G. and Liang, X. Y. and Zhang, C. and Srdic, S. and Lukic, S.}, year={2018}, pages={173–179} }