A Multi-Mode High-Efficiency Fault-Tolerant Permanent Magnet Machine

This article proposes a new multi-mode high-efficiency fault-tolerant permanent magnet machine with an inner stator to place AC field windings. The q-axis current in the field windings enables the proposed machine to be driven individually or together with the armaturewindings. On the other hand, the flux can be regulated by applying the d-axis current to the fieldwindings. As a result, multiple operation modes are realized. The proposed machine can run in different modes at different torque and speed operating conditions, implementing the multi-zone high-efficiency operation. Meanwhile, a new fault-tolerant control method can be applied in the proposed machine by combining themode switching and compensation current in the healthy windings, thus improving the efficiency under fault-tolerant operation. Moreover, the multizone high-efficiency regions of the proposed and conventional machines are investigated. The proposed and traditional fault-tolerant methods for the proposedmachine are compared. The results reveal that the proposedmachine offers a larger high-efficiency region and is capable of stronger fault tolerance. Furthermore, since the double stators in the proposed machine need to operate individually, a swallow-shaped rotor with auxiliary salient poles is adopted to reduce outer torque ripple and inner torque ripple. Finally, the experiments are performed to verify the predicted performances.