Comprehensive Review of Torque Ripple Minimization in Switched Reluctance Motor Drives: From Geometric Design to Advanced Digital Control

The Switched Reluctance Motor (SRM) has recently experienced a renaissance in industrial and automotive sectors, driven by its rare-earth-free construction, high fault tolerance, and robust thermal performance. However, the doubly salient structure of the SRM inherently produces significant torque ripple, which manifests as acoustic noise and mechanical vibration, limiting its adoption in high-performance traction applications. This paper presents an extensive review of the state-of-the-art techniques for torque ripple minimization. We categorize these techniques into two primary domains: magnetic design optimization (geometric modification) and advanced electronic control. Special emphasis is placed on the evolution from classical single-phase excitation to modern multi-phase excitation strategies (Improved Digital Control), Torque Sharing Functions (TSF), and Direct Torque Control (DTC). Through a comparative analysis of recent literature and fundamental electromagnetic theory, we demonstrate that while geometric alterations offer passive ripple reduction, active digital control strategies provide the dynamic adaptability required for wide-speed-range operation in electric vehicles.