Bidirectional Resonant Converter with Integrated Magnetics for On-Board Chargers

Electric vehicles (EV) are usually equipped with an on-board charger to recharge the vehicle's drive battery in every place where power sockets are available. A bidirectional charger can also be used to transfer energy back from the battery to the AC side for grid support. In addition, an active bridge on the secondary side enables synchronous rectification in order to reduce the conduction losses. This paper presents a bidirectional LLC resonant converter with integrated magnetics and a synchronous rectification detection circuit. Laboratory measurements revealed a maximum efficiency eta = 98.1 % in charge mode and eta = 97.2 % in discharge mode.