Pulsed transformer base drives for high-efficiency high-current low-voltage switches

An overview of the literature on base drives is followed by a description of a novel transformer-coupled base drive circuit that is particularly suitable for high-current transistor switches. It has the advantages of very low component count and cost, small size and high efficiency with no driver transistors being rated at full base current. The operation of the main transistor in deep saturation results in low conduction losses, and the dynamic characteristics of the switch are shown to be suitable for inverter applications. A simple mathematical model is proposed and experimental results on a drive for 350 A 100 V switch are given.>