Isolated interleaved-phase-shift-PWM dc-dc ZVS converter

This paper presents a new isolated dc-dc zero-voltage-switching (ZVS) converter, which is composed of two half-bridge converters associated in series operating at constant frequency. The converter can be seen as an alternative to the ZVS-phase-shift full-bridge dc-dc converter for high-voltage applications. The paper proposes a new command strategy, named interleaved phase shift, which allows equalization of the input capacitor voltage, where each capacitor shares one-quarter of the total input voltage. Due to phase-shift modulation, the current is equally shared among main switches, reducing the converter conduction losses, when compared with conventional pulsewidth modulation. Furthermore, the input capacitors voltage oscillations are reduced due to load variations, as well as due to input dc-bus 120-Hz ripple. Just as with a ZVS-phase-shift full-bridge converter, the proposed converter achieves ZVS in a wide load range, as a function of the transformer leakage inductance. The paper describes the analysis, operating principles, and design procedure for the proposed converter. Experimental results from a 1.5-kW prototype converter operating at 100 kHz with isolated 60-V/25-A output are presented to validate the theoretical analysis and to demonstrate the performance of the proposed converter. Index Terms--DC-DC converters, multilevel converters, power supply, soft switching.