A Three-Port Resonant DC/DC Converter With Fixed-Switching-Frequency PWM Control and Reduced Component Count for PV System

This paper proposes a three-port resonant DC/DC converter with fixed-switching-frequency pulse width modulation (PWM) method and reduced component count for the stand-alone photovoltaic (PV) system to process the power flow among PV source, battery and load. The proposed three port resonant converter (TPRC) employs the structure with dual half-bridge and coupled inductor to reduce the component count, which contains only four semiconductor devices and two magnetic components. By applying the centrosymmetric PWM method with two independent control variables, the proposed TPRC can realize decoupled port control, wide voltage regulation range and full-range zero voltage switching (ZVS) for all the switches with fixed switching frequency. In addition, the power-independent voltage gain and consistent gate driving logic in four power transmission modes help reduce control complexity and achieve smooth mode transition for the proposed TPRC. The operation principle, operation characteristics and design consideration of the proposed converter are analyzed in detail, and a 500-W experimental prototype with peak efficiency of 96.4% is established to verify the effectiveness of the proposed converter.