Rotor Resistance Estimation for Sensorless Induction Motor Drives with A Torque Ripple Reduction Method

The accuracy of rotor resistance is crucial for speed sensorless induction motor (IM) drives. Furthermore, the persistent excitation (PE) should be satisfied to distinguish rotor resistance from rotor speed for the simultaneous speed and rotor resistance estimation methods in steady states. Thus, the torque ripple is inevitable due to the injection on fundamental magnetizing current reference. However, few researches concentrate on simultaneous speed and rotor resistance estimation with attention paid to torque ripple reduction. To cope with this problem, this paper presents a joint signal injection method to satisfy the PE condition and relieve the torque ripples as well. Compared with the exiting methods, the joint signal of the proposed method is imposed both on magnetizing current reference and torque current reference. Theoretical analysis shows the amplitude of the ripples is significantly reduced. Finally, the effectiveness of the proposed method is verified on a 2.2kW IM setup.