Insulation failure prediction in inverter-fed induction machines using line-neutral voltages

This paper applies a new condition monitoring technique to inverter-fed induction machines. Regardless of the harsh switching (PWM) environment of adjustable speed drives, stator turn faults are detectable from the sum of the machine line-neutral voltages. The work focuses on an experimental validation for a range of machine synchronous speeds and loads, but also addresses two concerns when using the technique in an inverter: additional filtering demands; and means to obtain the line-neutral voltages. The technique of obtaining line voltages from the DC-link capacitor allows this technique to predict failure in both the machine and the power semiconductor switches