A simpler and more efficient iterative learning controller for PMSM torque ripple reduction

Abstract

Torque ripple minimization for permanent magnet synchronous motor (PMSM) based on PI-type iterative learning control (PIILC) strategy is discussed in this paper. Iterative learning control is naturally a good choice for minimize periodic torque ripple due to its data storage characteristic. To assure parameter convergence, infinite norm is used in controller design fo r learning gains. The approach proposed is not only simpler than conventional methods but more efficient because it is not necessary to detect electromagnetic torque and fe ed it back to the current loop. Several simulations are presented, suggesting that the method addressed is effective for constant-speed reference commands in torque ripple reduction.

A Fractional Delay Variable Frequency Repetitive Control for Torque Ripple Reduction in PMSMs

“…In order to minimize interferences between the speed PI controller and the RC and minimize convergence time, the latter is connected in a plug-in configuration in the proposed control topology instead of a parallel implementation as it was done in [8,10,12].…”

“…In such way, a lookup table would be required for generating the periodic current references which cannot be generated from the speed loop due to the limitation of its bandwidth. Alternatively, the RC can be placed in the speed loop where the controller can use the speed error [10,11] or the torque error [8,12] as an input producing periodic current references. Among these two methods, the latter one may be preferred to avoid the computation of current lookup tables.…”

A Variable Frequency Angle-Based Repetitive Control for Torque Ripple Reduction in PMSMs

“…In order to minimize interferences between the speed PI controller and the RC and minimize convergence time, the latter is connected in a plug-in configuration in the proposed control topology instead of a parallel implementation as it was done in [7,[9][10][11].…”

“…For example, repetitive control can work in conjunction with normal PI controllers in current loops to remove errors between periodic current references and current feedback [8]. Alternatively, the repetitive control can be placed in the speed loop where the controller can use the speed error [9][10] or the torque error [7,11] as an input producing periodic current references. Among these two methods, the latter one may be preferred to avoid computing current lookup tables.…”

“…Repetitive control has been applied successfully for torque ripple reduction in some existing works in scientific literature [7,[9][10][11]. RC is effective on reducing any periodic torque ripple without necessarily knowing the machine parameters, no matter the ripple is caused by cogging torque, inverter nonlinearities [12], flux harmonics, current offset, current scaling error, or mechanical unbalance.…”