Parallel asymmetric pulse-width modulation converters with same power switches for medium power applications

Abstract

A new zero-voltage switching (ZVS) half-bridge converter with three circuit modules is presented in this study to reduce the switching losses of power switches and current stress of passive components for medium power applications. Three circuit modules with the same power switches are connected in parallel at input and output sides. Thus, the switch counts are reduced compared with the parallel half-bridge converter with the same power rating. Each circuit module supplies one-third of load power to output side. Owing to the half-bridge converter leg, the voltage stress of each power switch is clamped at input DC voltage. Three centre-tapped rectifiers are adopted at low voltage side to share load current and reduce the size of magnetic cores. Asymmetric pulse-width modulation is adopted to regulate output voltage at the desired voltage level. Owing to the resonant behaviour by resonant capacitance [or output capacitance of metal-oxide semiconductor fieldeffect transistors (MOSFETs)] and leakage inductance (or external inductance) at the transition interval, power MOSFETs can be turned on under ZVS. The system analysis, circuit characteristics and design example of the proposed converter are discussed in detail. Finally, experiments with a 1620 W prototype are provided to verify the effectiveness of the proposed converter.