A Improved Condition Monitoring Method for Winding Insulation in Inverter-Fed Motor Using Matrix Pencil Method

The degradation speed of winding insulation in inverter-fed motors is accelerated due to high dv/dt voltage and overvoltage at the terminal. Therefore, many online monitoring methods are proposed based on current-measurement. However, high accuracy current sensors are needed for this application because the change caused by insulation degradation is minor. In addition, the large load current also affects the accuracy of online monitoring. The authors proposed a quasi-online monitoring method based on transient voltage response to solve this problem. In this method, the inverter injects a surge voltage into the winding and the voltage responses at the other terminals of winding are measured when the motor is at stand-still mode. In this paper, a new scenario is considered when asymmetrical aging happens in stator winding, while the existing method only considers symmetrical scenario. The matrix pencil method is also proposed in extracting the features in response, which is more accurate and lower demand for sampling equipment compared to the existing method. The experimental results prove that the proposed method can detect the insulation degradation in high accuracy.