Online Detection of MOSFET Gate Oxide Degradation in a Three-Phase Inverter-Drive Application

Failure in electrical machines or their drives can be catastrophic in safety-critical applications. Both silicon and silicon-carbide MOSFETs experience gate oxide degradation that leads to device failure. It is ideal to detect gate oxide degradation early using noninvasive, online techniques. In this article, an online gate oxide degradation detection method is proposed to reduce the reliability concern of using MOSFET switching devices. Gate oxide degradation causes a delay in phase current rise. Although the delay is short, it affects the voltage commands calculated in the controller. It is shown through analysis, simulation, and experiment that space vector pulsewidth modulation (SVPWM) duty cycle commands reflect the delay in phase current rise caused by gate oxide degradation.