A Reliable Passive Gate Driver Circuit for IGBT in Traction Applications

In traction inverters for automotive applications IGBTs are predominantly utilized. In recent years, as the semiconductor devices are being developed to meet their highest possible performance limit in automotive industry applications, to improve the loss performance of the traction electric inverter, the design of gate driver is playing a major role. In the high frequent operation regions of the semiconductor devices, the worst scenarios that affect the switching speed are to be considered by the standard gate driver design. Especially, while choosing the gate resistors, under any conditions the stray inductance and the switch (IGBT) surge voltage induceddue to change in current must be lower than the device ratings. Load current and dc bus voltage reaching highest values are the worst cases that are considered. But practically, the inverter in traction applications chiefly operates at bus voltage a lot under the worst case voltage and low current regions. A passive gate driver circuit which alleviates the trade-off between high device stresses and low switching loss is suggested in this paper. Inthe proposed circuit just a resistor, two Zener diodes and a low voltage PNP BJT are additional when compared with standard gate driver circuit. The increment in potential cost is low and implementation of the proposed circuit is simple. To achieve low surge voltage across IGBT, faster dv/dt and less turn-OFF delay, the various phases in the turn-OFF transient are controlled separately in the proposed gate driver circuit. This methodology will be used for fast switching applications as the proposed process doesn't need any logic and control circuits, feedback circuits that may limit the bandwidth of the circuit.