Comparison of Fault-Tolerant Operations for Permanent-Magnet Hybrid Brushless Motor Drive

The permanent-magnet hybrid brushless (PMHB) motor adopts both DC field windings and PMs for excitation. It not only offers effective online flux control, but also flexible brushless DC (BLDC) or brushless AC (BLAC) operations. The key of this paper is to investigate two remedial strategies for fault-tolerant operations of the PMHB motor drive under open-circuit faults. First, by utilizing field excitation boosting, the reduced torque due to one phase loss can be remedied, the so-called remedial BLDC operation mode. Second, by reconstructing armature fields due to the healthy phase currents, the reduced torque can also be remedied, the so-called remedial BLAC operation mode. Finally, these two remedial operation modes are compared and verified by experimentation, hence confirming the validity of the proposed fault-tolerant PMHB motor drive.