Analysis of insulation characteristics of low-voltage induction motor driven by IGBT PWM inverter

IGBT PWM inverter driven induction motors for variable speed applications have been widely used since their introduction. Recently, stator winding insulation failures have attracted much concern due to high dv/dt of IGBT inverter output. In this paper, the detailed insulation test results of 26 low-voltage induction motors are presented. Six different types of insulation techniques are applied to 26 motors. The insulation characteristics are analyzed with partial discharge, dissipation factor, and discharge inception voltage tests. Also, breakdown tests by high voltage pulses are performed.