The Torque Ripple Reduction For Switched Reluctance Motor

With the continuous development of the motor industry,switched reluctance motor is a novel motor.It has a doubly salient structure and windings on the stator.Because there is no windings on the rotor.Contrasting to the traditional induction motor or DC motor,it has a simple structure,high fault tolerance,more control parameters and lower maintenance costs features.Switched reluctance motor has been increasingly used in various fields.However,because of its structural features and step-wise during operation,switch reluctance motor has strong nonlinearity and large torque ripple.Traditional control strategies can not meet the actual demand,which greatly limits the application of switched reluctance motor.Therefore,on the one hand,this dissertation is based on improving its speed tracking performance and increasing ability with load.On the other hand,this dissertation researchs on the drive and control strategy to achieve the ultimate goal of reducing the torque ripple.Given the nonlinear characteristic of switched reluctance motor and combining the advantages and disadvantages of three different flux models,this dissertation is based on flux nonlinear model.It also combines with the relationship between torque or flux and rotor position angle or phase current.The relationship is obtained by finite element analysis.In this dissertation,12/8 pole prototype simulation model is established by look-up table.The program of starting switched reluctance motor is discussed particularly.Because of the complexity of nonlinear flux model.linear model can not reflect the magnetic saturation characteristics of switched reluctance motor.It is different from induction motors and permanent magnet synchronous motors.Switched reluctance motor can not use coordinate transformation to achieve a goal that the electromagnetic torque is not affected by the rotor position angle.In order to achieve good dynamic response,this dissertation uses the theory of nonlinear output regulation and combines with the model of switched reluctance motor.Speed tracking controller is designed which can simplify the hardware structure of switched reluctance motor drive system by eliminating current sensors.By analyzing the source of generating torque ripple and the influence of overlap angle on the efficiency,this dissertation uses torque share function to reduce torque ripple.It can achieve high efficiency operation in lower torque ripple situation.The overall simulation model of switched reluctance motor drive system is established in MATLAB/Simulink and the control strategies are verified by simulation.The results have shown that the designed speed controller can achieve good speed tracking ability and carrying load ability.Torque ripple suppression strategy also has good torque ripple suppressing effect.As for switched reluctance motor drive system,hardware and software modules have been designed.A lot of simulation experiments have been carried out to verify the feasibility of the algorithm by using RT-lab simulation platform.