PI Controller Design for a 5-Phase Switched Reluctance Motor with Bipolar Excitation Segmental Rotor

Year 2025, Volume: 8 Issue: 1, 28 - 41, 28.03.2025

Erdal Büyükbıçakcı

https://doi.org/10.33187/jmsm.1637233

Abstract

Switched Reluctance Motors (SRMs) are a type of motor that converts electrical energy into mechanical energy using the variable reluctance principle in industry, electric vehicles, and renewable energy. However, due to the nonlinear characteristic of the magnetic circuit depending on the rotor position, the dynamic performance of SRMs varies according to the operating conditions and they need a powerful drive circuit and an advanced control algorithm for maximum torque and stable speed control. In this regard, our solution involves the implementation of a PI control algorithm in a novel ST-SRM configuration that has been previously documented and is distinct from the conventional SRM design, which features a 5-phase 10/8 pole segmental rotor and bipolar excitation. has been developed to enhance the motor's overall operating performance and boost energy efficiency. The rotor of this five-phase, 10/8 pole configuration motor is made of silicon steel sheet packs and a lightweight aluminium block, in which these packs are placed to reduce the motor weight. Thus, the magnetic flux follows a short-circuited path between neighbouring stator poles, preventing stray fluxes and increasing the torque generated per unit weight. Short magnetic flux loops are used by simultaneous excitation of two neighboring phases, which reduces core losses, minimizes torque fluctuations, and allows higher torque production. However, the mathematical model of the motor becomes more complex as the cooperation of two phases results in mutual inductances between the phases. In this study, the mathematical model of the ST-SRM in the state space is derived, and the equation set required to control the system is obtained. The developed driver circuit is designed in a dual microcontroller architecture to manage the dual-phase supply of the motor. In this configuration, the primary microcontroller governs the five-phase power circuit, while the secondary microcontroller executes the PI algorithm in response to the speed signal from the optical rotor position sensors and autonomously modifies the source voltage. The instantaneous voltage adjustment of the drive system enables the ST-SRM speed to be maintained at the reference value, contingent on the fluctuating load conditions, thereby enhancing stability and energy efficiency. Experimental studies have demonstrated the efficacy of the PI controller in maintaining motor speed at a target value despite variations in load and in effectively dampening deviations during speed transitions. The measured phase current waveforms exhibit significant overlap with the simulation results, thereby substantiating the accuracy of the mathematical model and control method. Instantaneous monitoring of quantities such as current and speed through the developed user interface reveals the satisfactory dynamic performance of the system and the reliability of the control algorithm. In conclusion, an innovative PI-controlled driving and monitoring system for ST-SRM has been designed and successfully implemented. Thanks to the integrated drive system, the stable operation of the motor under speed and load is ensured, and the user interface makes real-time monitoring of critical parameters possible.

Keywords

Mathematical model, PI control, Segmental rotor, Switched reluctance motor, Two phase excitation

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