HHO-Optimized Adaptive PI Control and Hybrid Smooth Torque Sharing Function For Ripple Torque Reduction in Switched Reluctance Motor

Abstract

Switched reluctance motors (SRMs) offer a simple and robust structure, but their doubly salient topology and sequential phase excitation result in significant electromagnetic ripple torque, particularly during phase commutation. This paper proposes a ripple torque  reduction strategy for a four-phase 8/6 SRM drive based on the combination of an error- and error-rate-dependent smooth adaptive proportional-integral (EDSA-PI) controller and a hybrid smooth torque sharing function (TSF). The EDSA-PI controller dynamically adjusts its proportional gain according to the magnitude and rate of change of the speed error, while its integral gain is adapted according to the speed error. An anti-windup mechanism is also incorporated to handle controller-output saturation. At the torque-sharing level, the proposed hybrid TSF preserves the conventional rising–constant–falling structure while combining linear and minimum-jerk polynomial transitions to provide smoother phase-torque transfer during commutation. The six EDSA-PI parameters are optimized offline using the Harris Hawks Optimization (HHO) algorithm through closed-loop MATLAB/Simulink simulations. The optimized controller is evaluated at two operating points, namely 500 rpm with a load torque of 5 N·m and 1000 rpm with a load torque of 7 N·m. Using the same hybrid smooth TSF in both configurations, the proposed EDSA-PI configuration reduces the steady-state torque ripple from 56.92% to 20.12% at 500 rpm and from 47.15% to 12.80% at 1000 rpm, corresponding to reductions of 64.65% and 72.89%, respectively. The results demonstrate that the combination of HHO-optimized adaptive speed control and hybrid smooth torque sharing can substantially improve the electromagnetic torque quality of the investigated four-phase 8/6 SRM drive.