Research On Key Technology Of Torque Ripple Suppression Of Switched Reluctance Motor

Switched reluctance motor has many advantages,such as simple structure,low cost and good speed performance.It has been widely used in the fields of household appliances,electric tools and industrial servos.However,its unique double salient pole structure causes large torque ripple when the motor operates at low speeds,which limits the development of switched reluctance motors.In order to get smaller ripple at low speed,this paper mainly studies the suppression strategy.First of all,this paper introduces the development and research status of switched reluctance motor at home and abroad.And it describes the basic structure,working principle,mathematical model and basic control strategy of switched reluctance motor.Besides,it analyses the reason for the torque ripple of the motor.Secondly,in view of the large torque ripple of the switched reluctance motor when running at low speed,it analyses several main torque ripple suppression control strategies recently.And a current chopper controller based on fuzzy logic rules is designed.According to different current deviation values and load change rates,it determines the output PWM duty cycle size,which controls the on-time of the switch tube,reduce current fluctuations during steady-state operation.And it combines with the torque sharing function control strategy to control the torque fluctuations in the commutation interval,which outputs constant torque and reduces torque ripple.Furthermore,an improved simulation model of the current chopping control system was built using simulation software.And the different modules in the simulation model,such as the motor body,torque sharing function,current improvement algorithm are specifically analyzed.Compared with the traditional current chopping control system,the parameters such as current and torque in the model are analyzed.Finally,this paper designs hardware and software of system,and determines the control plan that switches different control modes according to different speed settings,which mainly voltage PWM mode,speed-current double closed loop mode and angle position control mode.When the speed is lower than 450 rpm,the motor is in Voltage PWM mode,and when the motor is between 450 and 1000 rpm,the motor is in the speed-current double closed-loop mode.In both modes,the improved current chopper controller is used,the speed reaches 1000 rpm,and the control mode is switched to angle position control mode.Besides,three-phase 6/4-pole and three-phase 12/8-pole switched reluctance motor control system experimental platforms were built respectively.At the same time,a new type of positioning magnetic ring design is adopted on the 6/4 pole motor to simplify the positioning steps.At last,no-load and load experiments were carried out.Verified by simulation and actual measurement platform,the improved current chopper controller can output stable torque and effectively reduce the torque ripple of the motor at low speed.