Reconfigurable LLC Resonant Converter for Wide Voltage Range and Reduced Voltage Stress in DC-Connected EV Charging Stations
Yu Zuo, Xiaobing Shen, Wilmar Martínez
Abstract
To meet the charging demands of current electric vehicles (400 V and 800 V) and next generation powertrain architectures (1200 V), this letter introduces a reconfigurable <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter connected to dc charging stations, capable of supporting a wide output voltage range for low-, medium-, and high-voltage EV charging by selecting various inverter and rectification methods. Unlike traditional <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> pulse frequency modulation approaches, the proposed converter maintains high efficiency across the entire output range and operates at a narrow switching frequency. The converter design features a stacked structure on both primary and secondary sides, including stacked half-bridges, diodes, and capacitors, which halves the voltage stresses on switches and diodes. This configuration also possesses voltage self-balancing among the stacked capacitors. In addition, soft-switching is achieved throughout the wide voltage range. Finally, experimental results from a prototype with an 8:1 output voltage ratio validate the feasibility of the proposed scheme.