Stator Turn Fault Detection by Relative Voltage Residual Slopes With High-Frequency Injection

Stator turn fault has been recognized as one of the most extreme faults for permanent magnet (PM) machines, which needs to be detected promptly and reliably. To this end, a new turn fault detection scheme based on relatively voltage residual slopes (RVRSs) with proper high-frequency (HF) injection is proposed. The HF analytical model of the machine under turn fault conditions is deduced, and the HF RVRSs are derived based on three stationary coordinate systems established for each phase. The results reveal that there are significant HF voltage residuals on the
$\alpha $
-axis when using faulty phase as the reference, while it is negligible on the relative
$\beta $
-axis. To enhance the sensitivity of fault detection and localization, RVRSs are proposed to amplify the amplitude difference in HF voltage residuals between the relative
$\alpha \beta $
-axis, and the HF RVRSs can be calculated without additional voltage sensors. To validate the effectiveness and robustness of the proposed method, extensive experiments have been conducted on a 5-kW PM machine under different speeds and loads.