Low Torque Ripple Control Method For Switched Reluctance Motor Drives

Switch reluctance motor(SRM) has many advantages, such as simple and solid structure, small starting current, strong fault-tolerant capability, flexible control and highly cost effective so that it gets wide attention in recent years. It has been used in many industrial circles like mining, oil exploitation, the driving of the electric vehicle, household appliances and so on. Because of the double salient construction of the SRM and the characteristic of saturation nonlinearity of the flux linkage, it makes a greater torque ripple and noisy, which restricts switch reluctance motor from a further development and application in the industrial area. How to effectively decrease the torque ripple gradually becomes one of the hot topic in the study of the switch reluctance machine. This article proposes an optimal control strategy of the torque ripple based on online compensation and correction of the torque sharing function, aiming at decrease the torque ripple.Firstly, this article introduces the research status of the switch reluctance motor in the field of optimizing the torque ripple, the basic operating principle and mathematical equations. Then it lists the flux linkage and torque modeling methods, and creates a model of switch reluctance machine used by this article.Later on, this article introduces basic control method of switch reluctance motor, operating characteristic and four conventional torque sharing function and gives the evaluation criterion of the torque sharing function. On the basic of the given torque sharing function, this article compares the torque, flux, current, rate of change of flux linkage waveform and the loss of four traditional torque sharing function. Then this article lists the off-line analysis of the influence of opening angle, overlap angle, expected torque on the torque sharing function of the rate of change of the flux change rate and loss.Further more, switching angle, overlapping angle, expected torque make a great influence on the torque sharing function, and there are different optimum switching angle and overlapping angle in the different operation condition. However, it is hard to directly confirm torque ripple off-line. So, we use the rate of change of flux linkage as an indirect way to evaluate torque ripple. This article uses the excellent search ability of the differential evolution algorithm in the process of search of the best switching angle of the torque sharing function. At the same time, it directly uses the torque ripple as the optimization target to confirm the best switching angle. The effect of the torque ripple of the torque sharing function is depending on the distance with the ideal output wave of TSF on current operation condition. So, This article takes in the real-time feedback signal of the torque to build the online compensation method of the torque sharing function in order to the further approximation of the ideal wave of TSF so that to decrease the torque ripple. This article building a simulation platform by the MATLAB/Simulink to check the search process of the switching angle in the using of the DE algorithm, and to contrastive analysis the effect of before and after the online compensation and correction in the torque sharing function of the four conventional torque sharing function. Then this article also study the influence of the load torque, opening angle, overlap angle and speed to the traditional torque sharing function control method and torque online compensation torque sharing function control method.At the last part, this article introduce the soft and hard structure of the experiment platform of the switch reluctance motor, and make an experimental verification of the suggested the torque ripple minimization control strategy of the switched reluctance motor. The experiment results show that the torque ripple minimization control strategy proposed by this article suggested is feasible and effective.