Research On Torque Ripple Reduction Of Switched Reluctance Motor

Switched reluctance motor(SRM)is a new type of speed control system developed in the past two decades.It has centralized windings on the stator and no winding or permanent magnet on the rotor.It has the advantages of durability,low cost,wide speed range and strong fault tolerance.It has been widely used in some occasions where frequent start-stop and positive-reverse operation are frequent.However,due to the doubly salient structure of SRM and the high non-linearity of inductance,the switched reluctance motor will produce serious torque ripple when it works,especially at low speed,which limits its application and development.Torque ripple can be suppressed by optimizing the motor structure and improving the control strategy.This paper mainly studies the control strategy to improve the overall performance of SRM speed control system.Firstly,the paper studies the advantages and disadvantages of the operating principle of the switched reluctance motor and the conventional control method.The reasons for the torque ripple of the switched reluctance motor are introduced,and the direct torque control method is adopted to reduce the torque ripple.The paper analyzes the basic theory of direct torque control of switched reluctance motor and explains the establishment process of voltage space vector.On this basis,the simulation model of direct torque control of double closed-loop switched reluctance motor is established by using MATLAB/SIMULINK software.It shows that the direct torque method can better suppress the torque ripple of the motor compared with the current chopping control strategy.Based on the traditional direct torque control strategy of switched reluctance motor,in order to further improve the practicability,this paper combines the fuzzy control theory,designs the fuzzy adaptive PID controller,expounds the structure and construction process of the controller,and uses the newly designed fuzzy adaptive PID control system replaces the original fixed-parameter PID system,which improves the shortcomings of the fixed parameter PID in the face of nonlinear and control parameters.The simulation results show that the response speed and adjustment precision of the new system are better than those of the traditional PID method,which improves the dynamic and static performance of the system,and enhances the anti-disturbance and self-adaptability of the system.At the same time,in the conventional direct torque control technology,the reference value of the flux linkage is fixed,which makes the stator current value of the switched reluctance motor too large and increases the copper loss of the motor.Combined with the above fuzzy adaptive technology,the influence of different flux on system performance is analyzed,and the relationship between given flux and torque is given,and an improved method of fuzzy direct torque control with variable flux is proposed,and a model is built.The simulation results show that the variable flux control method can reduce the stator current amplitude in steady state,reduce the motor loss and suppress the torque ripple.In addition,the problem of excessive stator current amplitude during motor start-up is further studied.The current control module is added to the above method,which can reduce the current amplitude during start-up and improve the overall performance of the system.In conclusion,his paper focuses on the direct torque control technology of switched reluctance motor,designs a fuzzy adaptive PID control model,proposes an improved direct torque control method with variable flux linkage,and combines with current control module to improve current control ability,the simulation results in MATLAB show that the control strategy proposed in this paper is feasible.