Analysis of a ZVS Converter with the Balanced Output Currents

A new three-level zero voltage switching (ZVS) pulse-width modulation (PWM) converter with the balanced output currents is presented for medium input voltage and high load current applications. Three-level converter with two clamped diodes and one flying capacitor is adopted to reduce the voltage stress of power semiconductors for medium voltage application and achieve ZVS operation for power MOSFETs. In order to reduce the size of the magnetic core and copper windings and to decrease the current rating of the rectifier diodes, three circuit cells are adopted in the proposed converter for high current applications. In each circuit cell, two transformers with a series connection are used in order to balance the output currents. To overcome the drawback of a wide range of switching frequencies in conventional series resonant converters, the duty cycle PWM control is adopted in the proposed circuit to achieve ZVS turn-on for power MOSFETs and zero current switching (ZCS) turn-off for rectifier diodes. Finally, experimental results are provided to demonstrate the performance of the proposed converter.