Effects of WBG Devices in Medium-voltage Inverters on Induction Machine Stator Insulation

Wide bandgap (WBG) power semiconductor devices, such as SiC and GaN, have broadened the applications of motor drives in medium- and high-voltage regimes by pushing the limits of voltage, frequency, and power. These advantages of WBG inverters are being leveraged in aircraft and ship industries as they move towards next generation more- and all-electric designs. While the superiority of WBG technology in terms of faster switching, greater voltage breakdown strength, and short recovery time are known, its effect on the motor drive insulation is relatively unknown. This paper focuses on high-voltage high-frequency WBG inverters and analyses their effect on medium-voltage machine insulation. Specifically, analysis of dielectric stress and leakage current density is carried out on a 3-phase medium voltage motor's stator ground-wall insulation excited by a 2 level hex-bridge WBG inverter and a 3 level multilevel inverter in Ansys Maxwell and the results are presented.