Flux-Trajectory-Optimization-Based Predictive Flux Control of Permanent Magnet Synchronous Machines

Abstract

This article proposed a predictive flux control strategy for permanent magnet synchronous machines based on flux trajectory optimization. Instead of minimizing the instantaneous flux tracking error at the end of each sampling period, the effect of different control sets on flux trajectories within the entire sampling interval is taken into account in the cost function. As a result, steady-state torque and flux ripples can be suppressed. Besides, inaccurate sector determination found in the conventional predictive control strategies can be successfully avoided. As well as highly dynamic performances inheriting from the predictive characteristics, enhanced steady-state torque control performances can be guaranteed under different operating conditions. Although the extended control set is utilized to augment the control freedom and further reduce torque ripple, the control effect of the proposed algorithm does not rely on the increase of switching frequency. Compared with the traditional predictive control strategies based on either finite control set or an extended control set, a superior control effect can be obtained while keeping a low switching frequency. Moreover, duty cycle signals are directly obtained in the prediction process, and no additional space vector pulsewidth modulation method is needed. Experimental validations and comprehensive comparison are conducted to demonstrate the effectiveness of the proposed strategy.