Speed Harmonic Based Decoupled Torque Ripple Minimization Control for Permanent Magnet Synchronous Machine With Minimized Loss

This article proposes a closed-loop decoupled current control for torque ripple minimization (TRM) of permanent magnet synchronous machines (PMSMs) by using the speed measurements. In the proposed control, a decoupled scheme is developed to control the harmonic currents for TRM, in which the control of phase angle and magnitude is decoupled to simplify the controller design. The decoupled scheme consists of two PI controllers and one control rule: one PI is responsible for phase angle control, the other is responsible for magnitude control, and the control rule is responsible for coordinating the two PIs for TRM. The harmonic currents can produce additional loss, and thus this paper derives the optimal condition for TRM with minimized loss. With the derived condition, one can control q-axis current and calculate d-axis current from the derived condition, which can minimize the torque ripple with minimized loss and simplify the control structure. The proposed decoupled approach is evaluated with extensive experiments and comparative study on a laboratory PMSM drive.