Torque Ripple Reduction Using Even Harmonic Average Periodic Delay Repetitive Control Under Single-Phase Open-Circuit Fault of PMSMs

This paper proposes a torque ripple reduction control method under single-phase open-circuit (SPOC) fault of permanent magnet synchronous motors (PMSMs). The proposed method consists of a dq-axis harmonic current reference generator and an even harmonic average periodic delay repetitive controller (EHAPDRC). The dq-axis harmonic current reference generator produces a compensatory current reference to reduce torque ripple caused by spatial harmonics, regardless of the fault. The torque ripple, derived from the post-fault PMSM model, contains even harmonic frequencies of the motor's fundamental electrical frequency. By operating in parallel with a conventional proportional-integral (PI) current controller, the EHAPDRC ensures accurate current regulation to reduce the torque ripple of PMSMs under various speed and torque conditions. The design methodology for EHAPDRC is detailed, and the stability of the proposed control strategy according to speed and parameter variations of PMSMs is analyzed. Experiments on a surface-mounted PMSM (SPMSM) are conducted to verify the torque ripple suppression performance of the designed controller at various speeds and torques under fault conditions.