High-Speed Gate Voltage Control Method Equalizing Loss of Many Parallel MOSFETs

Abstract

It has been said that connecting MOSFETs in parallel makes power consumption reduce without concentrating current on one of MOSFETs easily, because the resistance of MOSFET have a positive temperature characteristic. But switching MOSFETs under low voltage and high current condition causes concentration of switching loss owing to unbalance of avalanche characteristics of MOSFETs and the concentration of switching loss leads a MOSFET to thermal destruction. In this paper, a novel gate drive circuit dividing the switching loss equally between MOSFETs connected in parallel is proposed. The surge energy at turn-off time is not consumed by the avalanche characteristic of MOSFETs, but by the channel resistance of the MOSFET, because the new circuit controls the gate voltage. The switching loss in the new circuit hardly increases compared to the conventional one, because its switches operate with a high-speed response.MOSFET