Novel Characterization of Si- and SiC-Based PWM Inverter Bearing Currents Using Probability Density Functions

The high frequency PWM voltage pulses from a two-level six-switch inverter produce common-mode in an electric machine’s windings, fraction of which appears on the machine shaft due to electrostatic (capacitive) coupling. When exceeds dielectric strength bearing lubricating grease, discharge machining (EDM) discharges occur within bearing, can lead premature failure. According pulsed theory, breakdown across increases with increase slew rate (dv/dt). Therefore, faster rise times wide bandgap devices are expected higher magnitude voltages and EDM currents. This paper presents circuit modeling currents compares current amplitudes silicon- silicon carbide-based inverters through experimental measurements statistical analysis using probability density functions. provides insights regarding correlation between failure number damage causing over time is key step developing lifetime prediction models.