A Novel Postfault Torque Control Scheme for Modular Multiple Three-Phase Machine

Modular multiple three-phase machine (MTPM) systems are capable of continuous operation after winding or inverter failures. Such machines are considered promising candidates for integrated machine drive (IMD) systems, where reliability and compactness are critical. However, due to magnetic coupling among different modules, significant second-harmonic components appear in the electromagnetic torque, resulting in reduced average torque and degraded torque quality during fault-tolerant operation. To address this issue, a novel post-fault torque control strategy is proposed to explicitly consider inter-module magnetic coupling. The influence of magnetic coupling on modular machine operation under fault conditions is systematically elucidated from both magnetic and electric field perspectives. Then, an optimized current reference generation scheme is developed to compensate for the coupling effects. An enhanced proportional-integral-resonant (PIR) controller architecture is introduced to improve current tracking performance and operational reliability. Finally, both simulation and experimental results validate that the proposed control strategy effectively enhances the torque performance of modular MTPMs under fault conditions, without requiring additional hardware, demonstrating its suitability for high-reliability IMD systems.