An SRM Torque Ripple Suppression Method Based On Model Predictive Control

Switched Reluctance Motor(SRM)has the advantages of simple structure,reliable operation,and high efficiency.The speed control system,which is the switched reluctance motor drive(SRD),has the characteristics of wide speed range and large starting torque of the traditional AC/DC speed control system.It is widely used in electric vehicles,households appliances,aviation industry and other fields.The switched reluctance motor has a double salient pole structure.The magnetic circuit saturation,eddy current and hysteresis effect make the motor have strong nonlinearity.It is difficult to obtain an accurate mathematical model,and a large torque ripple occurs during motor operating.The magnitude of torque ripple will directly affect the speed regulation performance of the switched reluctance motor speed control system.Therefore,it is of great significance to study the SRM torque ripple suppression method.As a new control method,model predictive control(MPC)has been widely used in motor control,such as permanent magnet synchronous motor,brushless DC motor,induction motor,etc,and has achieved good control effects.According to the mechanism of torque ripple generation of SRM,a torque ripple suppression method based on improved angle position control(DAC)and a reluctance suppression method of switched reluctance motor based on model predictive control(TMPC)are proposed.The basic structure,mathematical model of the switched reluctance motor and the basic speed control principle of SRD system and several traditional speed control methods are introduced firstly in this paper.The relevant factors affecting the speed regulation performance and torque ripple of the speed control system are qualitatively analyzed.Based on the influence of turn-on angle and turn-off angle on torque,the DAC control method is proposed based on the traditional angle position control method(APC).The turn-on angle and the turn-off angle are adjusted online by the speed loop to realize the speed control of the motor and suppress the torque ripple of the motor.The motor torque is taken as the direct control target,and the TMPC control method is proposed.The basic principle of MPC is introduced.The nonlinear model of switched reluctance motor based on Ansoft is established.The mathematical model is used to obtain the motor torque value at the next moment according to the state quantities at the previous moment and the current moment sampled in real time,including the phase current of the stator winding,the rotor position and the bus voltage,and the objective function based on the torque ripple size is established;an optimal control sequence is obtained by combining the target function with the candidate sequence that changes the working state of the upper and lower tubes of the power variator;and thecontrol is obtained.The state value corresponding to the sequence is used in the switched reluctance motor predictive control system to suppress the motor torque ripple.In order to further verify the control effect of the proposed control strategy,an 11 kW three-phase 12/8-pole SRM is taken as the research object in this paper.The comparison experiment between DAC control method and traditional APC control method based on MATLAB simulation and the pure physical experiment based on TMS320X2812 DSP are completed.The experimental results show that the DAC control method is effective and the torque ripple suppression ability is strong.Through the comparison experiment of MATLAB simulation and RT-LAB based semi-physical simulation under DAC control method and TMPC control method,the two control methods proposed in this paper can realize the speed control of SRD system,and the speed regulation performance is good and effective,at the same time,the torque ripple can be effectively suppressed;in comparison,the TMPC control method has a stronger torque ripple suppression capability,while the motor has less over-adjustment time of speed under the DAC control method in the event of a sudden speed change in operating state.