Stationary Frame Fault-Tolerant Current Control of Polyphase Permanent-Magnet Machines Under Open-Circuit and Short-Circuit Faults

The paper presents a stationary frame control strategy to achieve optimal current control for star-connected polyphase permanent-magnet machine under asymmetric phase faults, namely, phase open circuit (OC) and phase short-circuit (SC) condition. Current regulation under these faults is particularly challenging because optimal torque control strategy generates nonsinusoidal current references with unbalance in both fundamental and higher order working harmonics, to achieve minimal copper losses and torque ripple under fault condition. Under field-weakening operation, voltage limit introduces additional control problems. The paper describes a solution for these control issues by employing a novel controller in stationary frame. This control strategy allows minimal reconfiguration of the control structure from healthy to postfault operation. Extensive simulation and experimental results are presented as validation for the proposed strategy.