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Technical Lecture

Power Electronics for Hybrid and Electric Vehicles

T08.4 - Reconfigurable LLC Resonant Converter for Wide Voltage Range and Reduced Voltage Stress in DC-Connected EV Charging Stations

Tuesday, March 18, 2025
9:30 AM – 9:50 AM ET
Location: Level Three, A314
The LLC resonant converter is known for its high efficiency and compact design but faces challenges in achieving a wide voltage gain. To overcome this, complex multi-stage circuits, hybrid control trategies, and multi-mode operations are often used. This paper introduces an innovative LLC resonant converter with a stacked bridge structure that simplifies this process by employing basic PFM and secondary turn-on/off control. The design includes a stacked half-bridge primary and a reconfigurable multi-voltage rectifier, extending the output voltage range while reducing voltage stress by half. The rectifier operates as a double-voltage rectifier at low output voltages and a quadruple-voltage rectifier at high output voltages, making it ideal for high-voltage applications like on-board charging and DC fast charging. Experimental validation with a prototype operating at 400V input and 200-800V output at 500W demonstrated effective soft-switching across the voltage range, confirming the design's feasibility.