Study On Sensorless Control For Switched Reluctance Motor

Switched Reluctance Motor Drive system(Switched Reluctance Motor Drive,SRD)a new type of mechanical and electrical integration ac Drive system,which is applied gradually in recent years.Because of its simple and solid structure,reliable performance and good performance in speed adjustment,it has broad development prospects in various fields.In order to get good motor control performance,accurate acquision of rotor position information is indispensable.Traditional SRD acquires rotor position information by the position sensor.It not only increases the complexity of the system,but also reduce the reliability of the system greatly.Therefore,how to implement sensorless switched reluctance motor control system becomes one of the important research subjects at present.The thesis first analyzes the composition of SRD and the traditional motor control strategy.Then the research is mainly focused on the current chopper double closed-loop control structure.Besides,the research applies the direct torque control which is widely used in the field of ac drive to the control of switched reluctance motor,thus forming the switched reluctance motor direct torque control system.In this way,the direct control of the instantaneous torque can be realized and the torque ripple is reduced.In the matlab/sumilink environment,two kinds of control structure are modeled and simulated,and the simulation results validate the correctness of the theoretical analysis,that is,the direct torque control system can well restrain the torque ripple of SRM.For the sake of the realization of sensorless control system,the thesis studies the simplified flux method and the sliding mode observer method.Simplified flux method is based on real-time magnetic chain compared with flux data that is stored in advance,to determine the commutation position time.Then we use the commutation time interval to estimate the rotor speed and Angle position information.This method can do well in recognizing the position Angle,after speed stability is realized.However,in the process of motor transient adjustment,its estimation of the rotor position is not so accurate.Therefore,the thesis studies the sliding mode observer method,based on direct torque control method of sliding mode observer.By building a second-order sliding mode observer,and using motor feedback of voltage,current value to estimate the rotor speed and position,the simulation results verify the feasibility of the two estimating methods.In order to improve the dynamic performance and robustness of the sensorless control system,compared to the traditional PI regulator,we designed the fuzzy PI controller.The simulation results show that the fuzzy PI can make the system achieve faster response speed,stronger anti-interference ability and better robustness.