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The fault-tolerant control method of dual three-phase permanent-magnet synchronous motor (PMSM) drives has gained more and more attention in some applications, such as aircraft system and offshore wind energy system. In this letter, the reason for the torque ripple caused by the standard control method has been investigated in view of the frequency domain after the occurrence of a single open-phase fault. Based on the theoretical analysis, a universal control scheme has been proposed for the dual three-phase PMSM drives with two isolated neutral points, which can be implemented under either healthy condition or fault condition. The key is to modify with a closed-loop controller on harmonic subspace with the notch filter. The proposed method not only realizes the seamless transition between two operation conditions without fault diagnosis but also avoids the reconfiguration of the control structure. Moreover, the system optimization of the minimum copper loss under postfault condition has been integrated into the proposed method. The experimental results are presented to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In standalone brushless doubly-fed induction generator (BDFIG) power generation systems, unbalanced and nonlinear loads can produce distorted power winding (PW) voltage, and consequently affects the normal operation of other loads and degrades the performance of the power generation system. Although the negative-sequence and harmonic components of the PW voltage can be eliminated by the conventional control methods implemented in either machine-side converter (MSC) or load-side converter (LSC), it causes higher voltage rating of converters and needs more current sensors. In this article, the detailed analysis for the impact of conventional control methods on the voltage rating of the two converters is presented. And then, an improved collaborative control method considering the power converter voltage rating is proposed, in which the MSC can be employed to eliminate the seventh-harmonic voltage of PW, and the LSC can be used to reject the negative-sequence and fifth-harmonic components of PW voltage without extra current sensors. The proportional-integral-resonant controller is applied to the current control loops in both MSC and LSC so as to obtain good current track ability. Comprehensive experimental results based on a 30-kVA BDFIG demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]