Detection and Classification of Demagnetization and Interturn Short Faults of IPMSMs

We present a method that detects and classifies demagnetization and interturn short faults (ISFs), which degrade the performance of permanent-magnet synchronous machines (PMSMs). Demagnetization and ISF are analyzed using models; we focused on changes of magnitude and angle of currents in the synchronous frame. Those two faults increase the magnitude of the input current compared with normal machines at the same load torque. However, our analysis suggests that demagnetization causes increase in the current angle β, whereas ISF causes decrease in β. We exploit this difference in response to classify the fault if one is detected in the PMSM. Experimental studies on interior-type PMSMs verify that demagnetization and ISF can be detected and classified in various operation conditions.