Search

A commutation torque ripple suppression strategy for the brushless DC motor (BLDCM) with commutation time is proposed. First, a torque model considering back electromotive force (back‐EMF) variation is presented, and the cause of commutation torque ripple is analysed. The results show that the commutation torque ripple of BLDCM is inevitable even if the non‐commutation current remains steady. On this basis, the influence and quantitative relationships of non‐commutation current and commutation time on commutation torque ripple are studied. Furthermore, two impact factors are proposed to comprehensively consider their effects on commutation torque ripple. The three‐phase windings are modulated in the commutation process at individual duty cycles. The comprehensive optimisation index of commutation torque ripple for different working conditions is obtained by calculating the relative relationship of the impact factors. The optimisation index determines the proper modulation duty cycles. Therefore, the motor parameters and working conditions do not limit the strategy. Finally, the experimental results verify the correctness of the theoretical analysis and the feasibility of the proposed strategy. The proposed strategy can reduce the commutation torque ripple by 16.28% and 21.80% and shorten the commutation time by 50.00% and 36.67% at low speed and high speed, respectively, compared with the conventional strategy. [ABSTRACT FROM AUTHOR]

This study proposes a novel inter‐turn fault diagnosis method for a permanent magnet synchronous machine. Search coils are set on every stator tooth to measure the tooth fluxes. The high‐order harmonics produced by the inverter are adopted to diagnose the inter‐turn fault existence and locate the fault tooth. The fault severity coefficient is proposed on the basis of theoretical analysis and can identify the fault severity. A comparative[AQ ID=Q1] analysis of a traditional method based on co‐simulation shows that the proposed method is sensitive and that the fault severity coefficient is accurate, intuitive and independent of the operating condition of the motor. An experimental platform is set up, and it validates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]