Analytical modeling of device-circuit interactions for the powerinsulated gate bipolar transistor (IGBT)

The device-circuit interactions of the power insulated gate bipolar transistor (IGBT) for a series resistor-inductor load, both with and without a snubber, are simulated. An analytical model for the transient operation of the IGBT, previously developed, is used in conjunction with the load circuit state equations for the simulations. The simulated results are compared with experimental results for all conditions. Devices with a variety of base lifetimes are studied. For the fastest devices studied (base lifetime=0.3 μs), the voltage overshoot of the series resistor-inductor load circuit approaches the device voltage (500 V) for load inductances greater than 1 μH. For slower devices, though, the voltage overshoot is much less, and a larger inductance can therefore be switched without a snubber circuit (e.g. 80 μH for a 7.1 μs device). The simulations are used to determine the conditions for which the different devices can be switched safely without a snubber protection circuit. Simulations are also used to determine the required values and ratings for protection circuit components when protection circuits are necessary