PMSM periodical torque ripple minimization using iterative learning control

To minimize the low speed torque ripple of permanent magnet synchronous motor(PMSM) used in high-performance servo system,the traditional torque ripple suppression methods were discussed,the main components of torque ripple were analyzed and its periodic characteristic was pointed out.Based on these,a new method using iterative learning control(ILC) was proposed to minimize the periodic torque ripple of PMSM with constant voltage frequency ratio control.The method minimizes the torque ripple by on line learning and compensating the control voltage.The controller was designed and its convergence condition was derived.The simulation results show that the iterative learning process has fast convergence speed and the torque ripple can be effectively minimized from 11.2% to 3.1%.This method needs a small amount of changes to the original system,the structure and algorithm are both simple and do not depend on the prior system knowledge and parameters,thus can obtain strong robustness.