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 PMSM drives. The proposed DNFD method consists of the current normalizer, the time-domain fault variable determinator, the Time-Domain to Angle-Domain Converter, Angle Normalizer and the fault identification encoder. The affections of the variable torque can be eliminated by the current normalizer while the affections of the variable speed can be eliminated by the angle normalizer, which is the main contribution of this article. In order to reduce the affections of the following factors: the calculation error of 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 threshold are required. Compared with the conventional single normalization fault diagnosis (SNFD) method, the DNFD method has better robustness. The effectiveness of the proposed DNFD method is verified by the experimental results.