Design considerations for a level-2 on-board PEV charger based on interleaved boost PFC and LLC resonant converters

In this paper, a two-stage on board battery charger is proposed for plug-in electric vehicles (PEVs). An interleaved boost topology is employed in the first stage for power factor correction (PFC) and to reduce total harmonic distortion (THD). In the second stage, a half bridge LLC multi-resonant converter is adopted for galvanic isolation and dc-dc conversion. Design considerations are discussed focusing on the reducing the charger volume, and increasing conversion efficiency over the wide battery pack voltage ranges. Detailed design procedure is provided for a 7.6 kW prototype, charging the battery with an output voltage range of 320 V to 420 V from 240 V, 60 Hz single phase grid. Results of the analyses show that the first stage PFC converter achieves THD less than 4% and power factor higher than 0.99, and the second stage LLC converter operates with high efficiency over the full output voltage range under ZVT.