Model-based Medium-voltage Induction Machine Insulation Material Characterization

The voltage and frequency handling capability of power converter modules have tremendously increased with the penetration of wide-band-gap (WBG) semiconductor technology in power electronics. However, very little is known about the effect of the high-voltage high-frequency transients exerted by WBG power electronics on insulation materials. This thesis investigates the effect of high-voltage, high-frequency transients on aging and breakdown characteristics of insulation materials. The aim of this research was to analyze this breakdown and develop the behavioral model of the breakdown time when such insulation materials are used in inverter-fed medium-voltage induction machines. As a part of this research, a series of breakdown tests have been performed on high temperature insulation films using high-voltage high-frequency pulses with a large slew rate (dV/dt) of around 4GV/sec. Behavioral models of breakdown characteristics were modeled as a function of film gauge (insulation material thickness), pulse voltage (breakdown voltage) and frequency under simulated pulse-width-modulated wave forms. The testing methodology and the modeling methodology have also been developed.