Minimising power losses and torque ripples of permanent-magnet synchronous motor by parallel execution of a two-stage predictive control system

Abstract

In this study, an advanced predictive control system is proposed which consists of two cascade predictive controllers; the first one minimises the power losses while the second one minimises the torque ripple. In the first controller, motor losses are formulated as a function of stator-flux linkage components. Then, the optimal stator-flux linkage vector which causes the minimum losses is found by adopting fast-iterative shrinkage thresholding algorithm (FISTA). The second controller is a predictive direct torque controller adopted to control the stator-flux linkage and torque directly. In this controller, torque ripple is formulated as a function of the stator-voltage vector. Then, the optimal voltage vector which causes the minimum torque ripple is found by adopting FISTA. In the second controller, deadbeat control of the stator-flux linkage is considered as a constraint in minimisation of torque ripple. To assess the effectiveness of the proposed control system, performance of the motor is assessed through various experimental tests, where the results confirm that the proposed control system minimises the power losses and torque ripple, simultaneously. The comparative assessment with the recent predictive controllers indicates that the proposed control system has higher efficiency as well as lower torque ripples in all operating points. © 2020 Institution of Engineering and Technology. All rights reserved.