Predictive Compensation-Based Harmonics Suppression for Speed-Sensorless Induction Motor Drives With Improved Feedback Gains

The adaptive magnetizing current control (AMCC) has been presented for speed-sensorless induction motor (IM) drives to enhance speed observability around zero stator frequency. However, adaptive variations of magnetizing current result in inevitable harmonics of speeds and torque. Addressing this problem, this article proposes a predictive compensation-based AMCC (PC-AMCC) method to compensate the reference of torque current and relieve the harmonics of speeds and torque. With the equivalent model of synchronous speed control (SSC) loop, the analysis is carried out to clarify the origin of harmonics. Then, the torque current variations are predicted by tangent of electromagnetic torque in sampling periods according to the variations of stator current and torque current error. On this basis, the reference of torque current of current loop can be compensated to relieve the hysteresis effect and suppress speeds and torque harmonics. Furthermore, the selections of feedback gains are elaborated with respect to flux error in low-speed motoring region. Finally, the effectiveness of the proposed method is verified on a 2.2-kW IM experimental setup.