Torque Ripple Reduction in Sensorless PMSM Drives

The paper proposes a method for the compensation of the torque ripple that is caused by motor unidealities in sensorless permanent magnet synchronous motor drives. The sensorless control of the interior-magnet motor is based on a speed-adaptive observer augmented with a pulsating high-frequency signal injection technique at low speeds. The harmonics in the permanent magnet flux and stator inductances are taken into account in the estimation, and a torque ripple compensator is developed for suppressing the harmonics in the estimated electromagnetic torque. The high-bandwidth current control required for torque ripple reduction is based on additional PI controllers implemented in reference frames rotating at the harmonic frequencies. Simulations and laboratory experiments show the effectiveness of the proposed method