A Bridgeless Isolated Half-Bridge Converter Based EV Charger With Power Factor Preregulation

Conventional full-bridge and half-bridge (HB) converters are quite popular for front-end power factor preregulation (PFP) in electric vehicle (EV) battery chargers. Discontinuous conduction mode (DCM) operation at high power causes increased oscillation in the circuit. These oscillations increase with parasitic components of circuit. During deep DCM operation, these oscillations are seen to be significant and contribute to harmonic content in the input current. Therefore, a PFP bridgeless isolated HB converter based EV charger with reduced LC oscillation in DCM is presented in this article. To reduce LC oscillation, two diodes are used in series with minimum number of magnetic components. The design of proposed charger in DCM is illustrated to facilitate uniform battery current during constant current/constant voltage charging. The inherent advantage of reduced conduction loss with bridgeless topology is achieved. The performance of this isolated HB converter based charger is shown for improved oscillation characteristics and power quality operation at steady state and over a range of varying input voltages.