Research On Torque Ripple Suppression Of Switched Reluctance Motor Based On Torque Distribution

Switched Reluctance Motor's stator and rotor are two convex core structure,and only the stator is equipped with concentrated windings,so its structure is simple and firm,and the maintenance cost is low.But the non-sinusoidal winding current and the magnetic circuit saturation,hysteresis effect and mutual inductance which create nonlinear magnetic field have a severe effect on the establishment of mathematical model for SRM,so it is difficult to get the simple and unified analytical model.The traditional control methods do not consider the smooth transition of torque during commutation process,so there will be a large torque ripple during the phase change of SRM.And torque ripple will cause rotation speed fluctuation,reduce the position control accuracy,weaken the performance of the speed control system,so torque ripple suppression is one of the pressing problems and research difficulties to be solved.First of all,this article elaborates the characteristics,principle and basic structure of SRM and SRD,expounds its current situation and development direction,then analyzes the basic equations,linear model,quasi linear model and nonlinear model of SRM,this paper also points out the advantages and disadvantages of different models.Secondly,the dissertation expounds the means of finite element analysis,then uses the finite element software Ansys Maxwell to establish its three-dimensional physical model and figure out the torque and flux linkage parameters based on the different rotor position and phase current.Then the interpolation method is used to establish the experimental motor's torque and flux parameters of the nonlinear model.Thirdly,the torque distribution control strategy,amplitude modulation control mode and a nonlinear PID controller are introduced in this paper.Then established the torque inverse model using interpolation method and set up a model of the experiment motor in Matlab/Simulink environment depending on the calculated torque and flux data.Aiming at the problem of SRM's severe instantaneous torque ripple,the fixed chopping limit of current chopping control method will be replaced by the fixed chopping time,which also can improve the efficiency and output of the motor.Aiming at the problem of severe torque ripple during the commutation,the torque ripple suppression method based on torque sharing function is described,which use the current closed loop to make the desired torque follow the given torque.At the same time,a class of nonlinear PID is applied to the control system,which has enhanced the system response speed and reduced the steady-state error.Finally,this paper takes TMS320F2812 as the core chip to design the Switched Reluctance Drive,which contains the asymmetry half-bridge circuit,MOSFET driving circuit,auxiliary power supply circuit,sampling circuit,photoelectric coding circuit and protection circuit.Also has written the SRM amplitude modulation control mode C language program based on torque distribution function and nonlinear PID,used the look-up table method to obtain real-time torque.Simulation and experimental results show that the proposed control scheme can effectively reduce the torque ripple,and the nonlinear PID can significantly improve the system response speed and reduce the steady-state error.