Disturbance Free Operation of Permanent Magnet Motor Drives Under Short Circuit Faults Using Center-Split Winding

Abstract

This paper studies permanent magnet (PM) motor drives with centre-split stator windings and auxiliary switches. By proper control algorithm, the proposed configuration guarantees continuous operation under various short-circuit conditions. Each of the stator phases is split at the center into two windings having equal number of turns and a common magnetic axis. Auxiliary switches are used to break the fault current path or to isolate the faulty winding. Under short-circuit fault condition; the current in the healthy half of the phase winding is controlled to cancel the rotor magnetic flux linkage of the shorted turns in the faulty half of the winding belonging to the same phase. This diminishes the detrimental fault currents in the shorted turns and allows the drive to continue operation under faulty condition. The currents in the healthy phases are controlled properly to generate the desired output torque. In this work, an optimal fault-tolerant control method is presented for controlling the healthy phase currents of a general n phase machine. Simulation results of a five phase PM machine are presented for verification of the proposed strategy.