A Variable Gain Nonlinear Current Controller for Torque Ripple Minimization in Switched Reluctance Motor Drives

In switched reluctance motor (SRM) drives, conventional current controllers often struggle to cope with the highly time-varying phase inductance and nonlinear back electromotive force (EMF). This article proposes a discrete-time adaptive sliding mode controller (ASMC) to reduce torque ripple and improve current tracking performance. Unlike conventional continuous-time designs, the proposed controller is formulated entirely in the discrete domain, making it suitable for digital implementation. An adaptive law based on the sliding mode surface dynamics mitigates current overshoot caused by time-varying phase inductance during commutation. To enhance robustness, a high-frequency switching term is incorporated to compensate for system uncertainties and nonlinear back EMF effects. The closed-loop stability of the system is rigorously proven using discrete Lyapunov theory. Experimental results demonstrate that the proposed ASMC significantly reduces torque ripple, lowers torque root mean square error (RMSE), and increases average torque compared to traditional controllers, validating its effectiveness for practical SRM applications.