An Efficient Torque Sharing Function for Optimizing the Commutation Zone Control Strategy of Switched Reluctance Motors

The development of electric vehicles can effectively solve the problem of energy shortage. At the same time, the torque ripple and efficiency are essential characteristics of the operational performance of electric vehicles. Switched reluctance motor (SRM) is widely used in electric vehicles due to its strong robustness, fast speed, and low cost. Therefore, it is very important to effectively reduce the torque ripple and improve the efficiency of switched reluctance motors. The following aspects are necessary to achieve efficient control and low torque ripple: (1) Distribute more torque to the phase with stronger torque generation ability in the commutation area. The outgoing phase has a higher torque generation ability at the initial position of the commutation zone. Then, more torque should be allocated to the outgoing phase in this area. The efficiency of the motor will be improved. In this situation, the actual torque can better track the reference torque when the incoming phase torque generation ability is weak. The torque ripple of the motor will also be reduced. (2) Reduce the negative torque of the motor. However, most previous studies have mainly considered one aspect. Therefore, a new TSF control method is proposed that divides the motor commutation area into two areas, which are controlled separately. At the end of the latter area, the phase current of the outgoing phase will decrease to zero, and the negative torque can be reduced. Meanwhile, less torque will be distributed to the incoming phase when the incoming phase has less torque generation ability. Firstly, the proposed torque sharing function (TSF) based on the sigmoid function is divided into two parts in the commutation area. Then, the two regions of the commutation area will be controlled separately. Secondly, a simple adaptive control strategy is adopted to obtain the relevant parameters of the proposed method. The optimal control parameters can be effectively obtained under different loads and speeds when the adaptive control strategy is adopted. In general, the complexity of the algorithm and the computational costs will be reduced. The experimental results of an actual switched reluctance motor show that the peak phase current is 17 A, the torque ripple is 38.89%, and the motor efficiency is 31.2% when the sinusoidal TSF control strategy is adopted at 500 r/min and 0.6 N∙m. However, the peak phase current, the torque ripple, and the motor efficiency are 12 A, 20.67%, and 36.7% at 500 r/min and 0.6 N∙m, and 18.1 A, 47.77%, and 40.4% at 1 000 r/min and 0.6 N∙m using the sinusoidal TSF control strategy. In contrast, when the proposed strategy is adopted, the peak phase current is 14.5 A, the torque ripple is 28.45%, and the efficiency of the motor is 44.3%. At 1 500 r/min and 0.6 N∙m, the peak phase current, the torque ripple, and the efficiency are 20.7 A, 52.22%, and 42.9% when the sinusoidal TSF control strategy is adopted, while they are 16.2 A, 31.33%, and 46.1% using the proposed strategy. The results show that the peak current of the proposed control strategy and the torque ripple will be reduced, and the efficiency of the motor will be improved at different working conditions. © 2024 China Machine Press. All rights reserved.