A Half-Bridge/Dual Stacked-Switches Structured AC/DC Electrolytic Capacitor-Less Bidirectional Converter With Soft-Switching for High-Voltage EV Charger

This article presents a half-bridge (HB)/dual stacked switches, fully soft-switched bidirectional electrolytic capacitor-less ac/dc resonant converter, tailored for high-voltage (HV) electric vehicle (EV) systems. The proposed converter integrates a closed-loop power factor correction (PFC)mechanism based on the $dq$ model of the input LCL filter, ensuring high-quality sinusoidal input current and reduced total harmonic distortion in both ac/dc conversion and dc/ac inversion modes. The front-end HB PFC circuit operates in continuous conduction mode with soft-switching operation, which eliminates the high peak current issue that happens in the switches in discontinuous conduction mode. Moreover, the dual stacked switches configuration of the proposed converter reduces the voltage stress on the switches to half of the dc-link and output voltage. A dedicated duty ratio-based closed-loop control system in both primary and secondary sides of the dual-stacked-switches resonant converter drastically reduces the double-line frequency voltage ripple, thereby eliminating the need for bulky electrolytic storage capacitors. Output voltage regulation in ac/dc conversion mode is achieved through variable frequency modulation, and soft-switching is maintained for all switches for all the operating condition in both modes. The performance of the proposed bidirectional converter is validated through a 1 kW, 120 V rms/750 V dc proof-of-concept prototype.