Novel parallel ZVS converters with shared power switches for medium power applications

A new DC/DC converter with parallel circuits is presented for medium voltage and power applications. There are five pulse-width modulation (PWM) circuits in the proposed converter to reduce current stress at low voltage side for high output current. These five circuits have the same power switches so that the switch counts are reduced compared with the conventional parallel converters. In order to reduce the converter size, conduction loss and voltage stress of power semiconductors, the series connections of power MOSFETs with high switching frequency instead of IGBTs with low switching frequency are adopted. Thus, the voltage stress of MOSFETs is clamped at half of input voltage. The switched capacitor circuit is adopted to balance input split capacitor voltages. Asymmetric PWM scheme is adopted to generate the necessary switching signals of MOSFETs and regulate output voltage. Based on the resonant behavior at the transition interval of power switches, all MOSFETs are turned on under zero voltage switching (ZVS) from 50% load to 100% load. The circuit configuration, operation principle, converter performance and design example are discussed in detail. Finally, experimental verifications with a 1.92kW prototype are provided to verify the performance of the proposed converter.