Enhanced Fault-Tolerant Control for Multi-Phase BLDC Motors: Achieving Smooth Torque Output

For the symmetrical winding multi-phase brushless DC (BLDC) motor, to reduce torque ripple after an open-circuit fault, this article proposes a fault-tolerant control method. When a power-switch device or phase winding experiences an open-circuit fault, the proposed method adjusts the conduction relationship of windings in specific sectors, thereby modifying the magnitude and direction of the magnetomotive force (MMF) to reduce torque ripple. After fault-tolerant adjustment, this method does not increase the phase current amplitude, maintaining the same level as during the fault to ensure stable output. The method does not require phase shifting of healthy phases and is implemented by actively disabling the conduction phases of specific sectors. The effectiveness of the proposed method is validated through experiments on a nine-phase BLDC motor test platform.