A robust multi-stage FOPI(1+PIDn) controller for precision control of switched reluctance motors under nonlinear and uncertain conditions

Switched reluctance motors (SRMs) are recognized for their robustness, simplicity, and cost-effectiveness, yet they face inherent challenges in precise speed regulation and torque ripple minimization due to their doubly salient structure and nonlinear magnetic characteristics. This study introduces a novel and high-performance FOPI(1+PID n ) multi-stage controller, specifically designed to address these critical limitations. The proposed control strategy synergistically integrates a fractional order proportional integral (FOPI) controller in the primary stage to enhance stability and transient response, with a proportional integral derivative controller augmented with a derivative filter (PID n ) in the subsequent stage to improve dynamic adaptability and noise rejection. To achieve optimal tuning of controller parameters, a particle swarm optimization with time-varying acceleration coefficients (PSO-TVAC) is employed, using a robust cost function that simultaneously minimizes speed and current errors over simulation time. The effectiveness of the FOPI(1+PID n ) controller is rigorously validated through extensive simulations in MATLAB/Simulink under a range of adverse conditions: no-load, static and dynamic loads, time-delay-induced nonlinearity, stepwise load increments, and parameter uncertainties for sensitivity analysis. Comparative assessments against conventional PID, PID n , and FOPID controllers demonstrate that the proposed controller consistently achieves superior performance, with an average improvement exceeding 45% across key dynamic response metrics including rise time, settling time, overshoot, and torque ripple. Notably, the proposed controller exhibits a 57% reduction in the cost function, a 65% reduction in integral of squared error (ISE), and enhanced robustness under uncertainty, establishing its efficacy for real-time control applications in SRMs. This work advances the state-of-the-art by offering a simple yet powerful control architecture that fuses classical and modern optimization techniques to deliver ultra-fast speed tracking, significant torque ripple attenuation, and strong resilience against nonlinear disturbances, thus broadening the operational viability of SRMs in precision-demanding industrial applications. • A novel multi-stage FOPI(1+PID n ) controller is proposed for precise SRM speed regulation and torque ripple reduction. • Combines fractional-order PI and filtered PID for robust, smooth transient control under nonlinearities and delays. • PSO-TVAC optimization automatically tunes controller parameters, ensuring fast convergence and robust performance. • MATLAB/Simulink tests show 57% lower cost function, 65% lower ISE, and 45% faster response than conventional controllers. • The FOPI(1+PID n ) controller provides efficient, scalable, real-time SRM control and supports future hardware implementation.