Current-Residual-Based Stator Interturn Fault Detection in Permanent Magnet Machines

Interturn short-circuit fault, also known as turn fault, is a common fault in electric machines, which can cause severe damages if no prompt detection and mitigation are conducted. This article proposes a turn fault detection method for permanent magnet machines based on current residual. After the impact of the turn fault is first analyzed on a simplified mathematical machine model to assess the fault signature, a finite-element model is developed to obtain healthy machine behavior. The residual between the measured and estimated currents by the model with the same applied voltages contains mainly the fault features. The quality of the fault detection can be improved because the fault signatures are enhanced, and the impact of the current controller bandwidth on fault signature is minimized. The dc components in the negative-sequence current residuals are extracted through angular integration, and their magnitude is defined as the fault indicator. The robustness of the fault detection against transient states is achieved. The effectiveness of the proposed method is validated on a triple redundant fault-tolerant permanent-magnet-assisted synchronous reluctance machine.