Water-cooled on-board charger with optimized cooling channel

This contribution deals with the design of a water-cooled on-board charger for electric vehicles. The charger consists of two power stages: a bridgeless power factor correction boost rectifier and an isolating resonant converter. Though wide-bandgap semiconductors with excellent reverse recovery behavior exist, the comparably high cost still advices the use of traditional silicon semiconductors. However, employing fast IGBTs in the PFC rectifier and trench MOSFETs in the resonant converter facilitate a reasonable maximum efficiency of about 96.5 %. Besides efficiency, also high power density is obligatory. Therefore, water cooling is used for maximized heat transfer. In order to achieve low pressure loss, the profile of the cooling channel is optimized by means of computational fluid dynamics. The cooling concept enables a size reduction of the charger, where 1.4 kW/l power density was achieved.