Thermal Stress Reduction of Power MOSFET in Electric Drive Application with Dynamic Gate Driving Strategy

While operating an electric drive under different load conditions, power semiconductor devices experience thermal stress which compromises lifetime. In this paper, a model based gate voltage control is proposed to reduce the thermal stress by shaping the profile of conduction losses. Thermal stability criterions are introduced, which confine the gate voltage range to prevent current focalization and local heat up. This method is verified by using a custom proof-of-concept gate driver that supplies an adjustable three-level gate voltage. A three-phase electric drive is prototyped, on which power cycling tests are conducted and the results confirm the thermal control method.