Diagnosis of Interturn Short Circuit Fault in BLDCM Based on Coupled High-Frequency Signal Injection

The Brushless dc motors (BLDCMs) are a key technology for electric vehicles (EVs) as they exhibit excellent performance in terms of high efficiency and controllability. However, their reliability poses a technical challenge where interturn short circuit (ITSC) faults are a major type of fault. Detecting these faults quickly and reliably can save lives and reduce operational costs. A method for diagnosing ITSC faults in BLDCMs is proposed in this article, which employs a coupled high-frequency (HF) signal injection technique. The HF detection signals are injected into the motor windings through a coupling circuit, and the three-phase HF currents at the injected frequency are obtained to analyze the fault characteristics. The root-mean-square (rms) ratios of the HF currents are used as fault indicators. The effectiveness of the proposed method is confirmed by both simulation and experimental tests. It is proven to be resilient to environmental factors and measurement noise. The developed technology will gain in popularity of the BLDCMs in the applications of green transportation such as EVs, electric aircraft, and ships.