Fault remedial strategies in a fault-tolerant brushless permanent magnet AC motor drive with redundancy

In this paper the fault-tolerant brushless permanent magnet AC motor drive with redundancy is investigated. The motor modules are designed to provide both magnetic and electrical isolation between phases and the redundancy is achieved by using two motor modules connected on a common shaft. The effect of potential faults on the output torque and torque ripple factor are examined and the fault analysis shows that the output torque will be reduced and the torque ripple will be increased after fault(s). Three fault remedial strategies are proposed to compensate the torque loss due to the fault(s) and their features are discussed as well. Zero torque ripple with minimum copper loss fault remedial strategy is the most suitable method which can result in minimum torque ripple factor with only a modest increase in copper loss comparing with the minimum possible value. The experimental setup of the motor drive is developed and the experimental test results are provided to verify the analysis results and the validity of the proposed fault remedial strategies.