Phase-Shifted PWM Converter With a Wide ZVS Range and Reduced Circulating Current

Abstract

A phase-shifted (PS) pulse-width-modulation (PWM) converter that can solve the drawbacks of existing PS full-bridge converters, such as narrow zero-voltage-switching (ZVS) range, large duty-cycle loss, large circulating current, and serious secondary-voltage overshoot and oscillation, is proposed in this paper. The proposed converter is composed of two symmetric half-bridge converters (TSHBCs) that are placed in parallel on the primary side and are driven in a phase-shifting manner. Their transformers are connected in series on the secondary side. At the output, a simple energy-recovery circuit (ERC) is employed. Due to this structure, the proposed converter has the advantages of wide ZVS range, less duty-cycle loss, reduced circulating current, and no secondary-voltage overshoot and oscillation, which results in the reduction of rectifier diodes' voltage stress and EMI. Therefore, the conversion efficiency is higher and the cost of the secondary rectifier is reduced compared to its PS PWM counterparts. In this paper, the circuit configuration, operation principle, and relevant analysis results of the proposed converters are presented. Experimental results on a prototype converter realized with an 80-in plasma display panel sustain power module (320-385 V-dc input, 205 V-dc/5 A output) validate the theoretical analysis.