Monitoring of Gate Leakage Current on SiC Power MOSFETs: An Estimation Method for Smart Gate Drivers

Silicon Carbide (SiC) power transistors are more and more used in electric energy conversion systems. SiC power semiconductors devices, such as SiC metal-oxide-semiconductor field-effect transistor (mosfet) can operate at higher frequency and higher temperature compared to Silicon power mosfet or insulated-gate bipolar transistor. However, the maturity of the SiC technology is moderate compared to the well-known Silicon-based power semiconductor devices. Recent research works on reliability of SiC power mosfet identified gate leakage currents as an ageing indicator. The monitoring of ageing indicators during normal operation may definitely help to predict damages and simplify the maintenance on the energy conversion systems. Due to the low amplitude of gate leakage currents, its direct measurement is difficult even under laboratory conditions and requires an offline characterization. This article presents a new method for estimating the gate leakage current using the gate drive circuit. The proposed method takes advantage of the internal structure of the typical gate drivers used to command SiC power mosfets.