LLC Resonant Converter for Fast Electric Vehicle Charging Module with a Reconfigurable Bi-Directional Switch

This paper presents a new reconfigurable LLC converter in fast electric vehicle (EV) charger applications. By using a reconfigurable bi-directional switch, the proposed converter restructures the secondary side windings of the transformers of two LLC converters in series or parallel, providing an adjustable effective turns ratio. The most powerful advantage of the proposed converter is the simple structure for reconfiguration. Also, the proposed converter does not contain capacitor in series with the resonant current path, which is appropriate for a large charging current in fast EV charger. Furthermore, the proposed converter maintains identical for the same switching frequency range both 400 V and 800 V batteries, due to the same quality factors in both cases. To verify the effectiveness of the proposed converter as a fast EV charger module, a prototype converter with a 150-1000 V and 25 kW/62.5 A output was constructed.