Post-Fault Operation of Fault-Tolerant Three Phase Surface Mounted PMSM

Fault tolerance is a necessity for motor drives used in safety-critical applications. Permanent magnet synchronous motor (PMSM) with rare-earth magnets have high torque density, high efficiency. To achieve fault-tolerance, those are to be designed with high inductance. With this, currents during winding short-circuit get limited. In this paper, a fault-tolerant three-phase PMSM operation during its post-fault (both open and short-circuit conditions) situation is presented. In this work, a fault situation refers to one of the phases becoming open or short. The proposed control involves modelling the motor in stationary reference frame. With this model, closed-form expressions are obtained for the currents in the remaining healthy phases during post-fault operation. Using these expressions, speed control during post-fault operation is proposed such that the torque ripple gets minimized. To experimentally validate the proposed control, a fault-tolerant PMSM (12-slots, 10-poles, fractional slot concentrated winding) is designed and prototyped. Results pertaining to motor design validation and torque-speed profile during post-fault operation are presented.