High-Efficiency Single-Stage Single-Phase Bidirectional PFC Converter for Plug-in EV Charger

Power factor correction (PFC) operation, high density, galvanic isolation, low cost, and high efficiency are the prime factors while designing an electric vehicle (EV) battery charger. The power electronic circuit topology plays a cardinal role for ac-to-dc power conversion with the abovementioned features. This paper presents an isolated single-stage single-phase bidirectional PFC ac/dc converter without an intermediate DC-link for EV charger application. The proposed topology comprises a current-fed push-pull circuit on the primary side and a full-bridge circuit on the secondary side via a high-frequency transformer (HFT). The proposed converter attains the natural commutation of the primary side semiconductor devices through zero current switching (ZCS). This lessens the hardware complexity and makes the topology snubberless or without a clamping circuit. This proposed configuration employs simple yet effective fixed-frequency pulse-width modulation. A novel modulation technique is established to ensure the soft-switching of the devices during all modes of operation with bidirectional power flow. This article explains detailed analysis, operation, and design of the new current-fed push-pull bidirectional configuration operated with novel modulation technique. Analysis and design have been validated by the PSIM 11 simulation results. Also, a 1.5 kVA proof-of-concept prototype has been designed and tested to verify the claims and demonstrate the derived converter performance with the proposed modulation scheme. The laboratory prototype has achieved an input power factor of 0.99, an input current total harmonic distortion of 2.67%, and a high efficiency of 96.7%.