Single Stage Isolated AC/DC LLC Resonant Power Conversion Stage with Reduced Current/Voltage Stress for Light EV Charger

The operation of PFC stage in hard-switching is quite common, which reduces overall conversion efficiency in two stage EV chargers. To cater this issue, a single stage direct AC/DC LLC resonant converter based EV charger design is presented in this paper. Converter utilizes interleaved concept at grid end and each interleaved phase realizes only half of grid voltage. This effective implementation reduces voltage stress across MOSFETs for its discontinuous interleaved inductor current mode (DIICM) operation. DICM design features small passive footprints and easy control implementation. A time weighted average designing (TWAD) design ensures zero voltage switching (ZVS) with reduced turn-off switching losses. Additionally, with DICM of interleaved state and TWAD design of LLC tank parameters, single charging current control loop provides DC link boost capability with charging current tracking. A O.5kW EV charger is designed to validate TWAD design technique and single stage AC/DC power converter.