Quasi-Online Technique for Health Monitoring of Stator Winding Insulation in Inverter-Fed Motor Using Switching Transient Voltage Response

The condition monitoring technique for stator winding insulation in inverter-fed motors has gained significant attention, though current methods relying on high-sensitivity current sensors for minor current signals pose limitations, particularly for larger motors. In contrast, voltage measurement offers heightened reliability. To address this, a quasi-online methodology capitalizing on the switching transient voltage response is proposed, thereby circumventing the necessity for current sensors and exclusively employing voltage sensors. This approach entails the inverter’s injection of surge voltage excitation into the stator winding, followed by the measurement of voltage responses at the terminals of the other two phase windings. Importantly, this technique enables the automatic identification of stator insulation condition during motor standstill, providing a non-intrusive and easily implementable solution compatible with existing motors.