Common-Mode and Differential-Mode Harmonic Current Based Insulation Degradation Detection Method for Aerospace Fault Tolerant Permanent Magnet Synchronous Motor System

To improve the system maintainability and the mission reliability, this article proposes the common-mode (CM) and differential-mode (DM) harmonic current-based insulation degradation detection method for the aerospace fault-tolerant permanent magnet synchronous motor (FTPMSM) system, which can detect the interturn (IT) insulation and groundwall (GW) insulation degradation. The CM and DM equivalent insulation degradation models are firstly proposed for the H-bridge drive-based FTPMSM system, which can accurately predict the CM and DM impedance behaviors associated with the insulation degradation. The high-frequency differential-mode (HFDM) and middle-frequency common-mode (MFCM) harmonic current-based insulation degradation detection methods are then proposed, which consists of DM and CM current extractor, band-pass filter, periodic root-mean-square (PRMS) calculator and degradation index calculator. The resulting detection method is noninvasive with simple structure and good robustness. The effectiveness of the proposed insulation degradation model is verified by the impedance analyzer, while the proposed insulation degradation detection method is verified by a six-phase FTPMSM experimental platform.