Double Normalization Fault Diagnosis Method for Open-Circuit Faults of PMSM Drives

In this article, a double normalization fault diagnosis (DNFD) method is proposed to cope with open-circuit faults of permanent magnet synchronous motor drives. The proposed DNFD method consists of a current normalizer, a time-domain fault variable determinator, a time-domain to angle-domain converter, an angle normalizer, and a fault identification encoder. The affections of the variable torque can be eliminated by the current normalizer, whereas the affections of the variable speed can be eliminated by the angle normalizer, which is the main contribution of this article. To reduce the affections of the following factors, i.e., the calculation error of the time-domain to angle-domain converter, the measurement noises of current sensors, the performance of the analog-to-digital converter, the sampling frequency, and the electromagnetic interference of the system, the hysteresis comparator is employed, in which two fault thresholds are required. Compared with the conventional single normalization fault diagnosis method, the DNFD method has better robustness. The effectiveness of the proposed DNFD method is verified by the experimental results.