Fault-tolerant control of multi-phase permanent magnetic bearingless motors

The fault-tolerant control of multi-phase permanent-magnet bearingless motors (PMBM) is vital for their safe operation. In this paper, the mathematical model of current-controlled multi-phase PMBM with different open-circuit faulty phase(s) is analysed based on a uniform matrix. The fault-tolerant controllability of multi-phase PMBM is investigated in general and the feasibility of fault-tolerant control with arbitrary single, double or triple open-circuit faulty phase(s) for a six-phase PMBM is discussed in detail. Simulation results from finite-element analysis are presented to illustrate the levitation forces and torque under the proposed fault-tolerant control and experimental results are given to verify the proposed method.