Series connection of multiple MOSFETs using ZCZV commutation

Abstract

Series-connection of multiple MOSFETs using an improved Zero Current Zero Voltage (ZCZV) commutation cell in high power PWM DC-DC boost converter is introduced. It provides Zero Current Switching (ZCS) and Zero Voltage Switching (ZVS) simultaneously, at both turn on and turn-off of the main switches. Where single devices are unable to handle the open circuit voltages, series connection is the only solution. This method however faces the problem of ensuring equal voltage sharing among the series connected MOSFETs in their off state. An improved solution, which is to utilize ZCZVS (Zero Current and Zero Voltage Switching) cells with series-connection of multiple MOSFETs, is proposed. The basic analysis and operation of the ZCZVS for series-connection of two and four MOSFETs commutation cell applied to a boost converter are presented. The ZCZVS commutation cell has been analyzed theoretically and verified experimentally. Two prototypes operating at 40 kHz were built and measured. Simulated and measured results are presented.