Severity Estimation of Inter Turn Short Circuit Fault for PMSM

This paper presents a novel method to estimate the number of shorted turns in a permanent magnet synchronous machine (PMSM) following the detection of inter turn short circuit (ITSC) fault and its location. In this proposed method, PMSM is excited through a low sinusoidal voltage at stand still condition to obtain the winding resistance and synchronous inductance by current response. It is shown that, the inter turn short circuit (ITSC) fault introduces variation in the current response which is used to calculate the number of shorted turns under zero fault resistance assumption. Using this practical procedure, the fault severity can be estimated directly in a straight-forward manner. In other words, the severity estimation for a given machine can be done without complex machine modeling or experiments on ITSC prototype with multiple taps. The findings in this paper are essential for a comprehensive solution including fault mitigation algorithms and post-fault operations. In order to verify the findings, a three phase equivalent circuit model supported by FEA results is used to take saturation and space harmonics into account. In addition, experimental results are presented to demonstrate the validity and practicability of the severity estimation.