The plasma extraction transit-time oscillation in bipolar power Devices-Mechanism,EMC effects, and prevention

Under certain conditions, radio frequency (RF) oscillations may occur during the turn off of bipolar power devices. These oscillations are related to the plasma extraction transit time (PETT) effect. The mechanism of the oscillation and the complex dependencies for the occurrence of the effect are discussed in this paper. Three-dimensional electromagnetic compatibility (EMC) simulation is used to investigate modifications of the power module layout that shift its resonance point and therefore, effectively suppress the unwanted RF oscillations. EMC measurements and examples of failures of power electronic equipment related to the occurrence of PETT oscillations demonstrate the necessity for suppressing this effect.