Simulink Model for Chopper Control of Switched Reluctance Motors

In the field of motor control, switched reluctance motors (SRMs) have gained significant attention due to their simple structure and high reliability. For 12/8 pole SRMs operating at low speeds, current chopper control (CCC) effectively addresses torque ripple issues. When implementing this control strategy through Simulink modeling, several key components require special attention.

First, establishing a nonlinear mathematical model of the motor is essential, accounting for magnetic saturation effects. The winding inductance exhibits periodic characteristics with rotor position variation, which represents the core modeling challenge. Secondly, designing a current hysteresis controller - the executive mechanism of chopper control - enables precise phase current regulation through setting upper and lower threshold values. In implementation, this typically involves creating a hysteresis comparator block that generates switching signals when current deviates from the preset band.

The Simulink control module primarily consists of three parts: position detection, current sampling, and PWM signal generation. Position sensors provide real-time rotor position information, which serves as critical input for determining the conducting phase. The current sampling subsystem compares actual phase current with reference values, utilizing hysteresis comparators to produce switching signals. The power drive circuit then activates or deactivates corresponding phase windings based on these signals, typically implemented using MOSFET/IGBT blocks with appropriate gate drivers.

For 12/8 pole motors, each revolution contains 24 stepping positions, requiring careful design of commutation logic. During low-speed operation, selecting appropriate current chopping frequency is crucial - it must ensure control accuracy while avoiding excessive switching losses. The model should incorporate state-flow or logic blocks to manage the 15-degree mechanical angle commutation sequence. Additionally, protection circuit modules must be included to prevent overcurrent damage to power devices, often implemented using current limiting blocks and fault detection algorithms.

This control method achieves smooth torque output in low-speed regions and demonstrates superior dynamic response characteristics compared to traditional control approaches. Through parameter optimization techniques, such as adaptive hysteresis band adjustment and PWM frequency tuning, torque ripple can be further reduced while improving system efficiency.