Sensorless position estimation in a fault tolerant surface-mounted permanent magnet AC motor drive with redundancy

Abstract

Although mechanical rotor position sensors are one of the least reliable parts in motor drives, past research in fault-tolerant PM drives has largely focused on motor and inverter topologies. While there has been substantial research on sensorless control algorithms, these are generally not directly applicable to the electrically isolated phase windings used in fault-tolerant PM drives. This paper proposes a position sensorless algorithm which is suitable for fault-tolerant PM drives and is capable of operating under fault conditions. The algorithm is based on examining the phase winding incremental flux linkages, and then estimating multiple incremental rotor positions using every pair of phases of the motor drive. Computer simulation results are provided to demonstrate the accuracy of the position estimation under both healthy and faulted conditions.