Characterization of winding insulation of electrical machines fed by voltage waves with high dV/dt

The insulation of electrical machines driven by power converters with pulse width modulation are subjected to repetitive surges due to fast changing voltage pulses and reflection phenomena in supply cable, as well as non-uniform voltage distribution in the stator winding. The overvoltage at motor terminals may lead to partial discharge inception accelerating winding insulation degradation and causing its premature failure. The implementation of wide bandgap power semiconductors as Silicon Carbide allows to create converters with high power density for variable frequency drive applications. The fast and high frequency switching of electronic devices based on wide bandgap semiconductors increase electrical stresses caused by steep voltage changing rates in controlled electrical machine. It may increase a risk of partial discharges and accelerate insulation aging and destruction. The experimental investigation and numerical simulation study performed in this work is essentially focused on the effects of impulse voltage with high dV/dt and high switching frequency on winding insulation robustness of inverter-fed electrical machines. Therefore, the work covers a number of issues related to electric drives, power electronics, electrical machines, dielectric materials and partial discharges.