Research On Model Predictive Control Strategy Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors（PMSM）have been used as mainstream drive motors in electric vehicles,aerospace and other fields,so it had attracted more and more attention from researchers.Therefore,it is of great significance to promote the development and progress of industry by studying the control strategy of PMSM to improve the important performance parameters output by PMSM.Due to the existence of the PI controller in the field-oriented control（FOC）designed based on the PI controller leads to the problem of a low dynamic response speed,saturation of the integrator,difficult to deal system constraints,fast response with overshoot and so on.After theoretically deriving and researching the model predictive control（MPC）,the improved MPC strategy is applied to the FOC designed based on the PI controller to realize the model predictive-field oriented control（MP-FOC）for the PMSM.Firstly,setting the d and q axis reference currents corresponding to different working conditions,and input the current into the mathematical model of the PMSM.Then the voltage vector combination corresponding to the six sectors and the zero-voltage vector combined with the deadbeat predictive control algorithm are used to calculate the action timet₁^x、t₂^x、t₀^xcorresponding to the three vectors,and the optimal control voltage vector combination is selected by the constructed objective function.When the effective time t₁^x、t₂^x、t₀^xof the effective voltage vector in the three vectors is negative or no solution,the voltage vector combination corresponding to the current sector or the adjacent sector is used as the optimal voltage vector in the next control cycle to ensure the important parameters such as current and torque of the PMSM will not be greatly distorted.Secondly,after determining the optimal control sectorN_opt and the corresponding action time t₁^*、t₂^*、t₀^*,the modulation process is performed to obtain the final action time of the reference voltage vector u_α^*、u_β^* based on the coordinate system.Then the reference voltage u_d^*、u_q^*under the dq coordinate αβ system is calculated by the motor rotor position angle and the corresponding action time₁t^*、t₂^*、t₀^*of the optimal voltage vector.Finally,The reference output voltage u_α^*、u_β^* was converted to the reference output voltage u_d^*、u_q^*in the rotating coordinate system by the Park transfer,and then use the space vector modulation unit SVPWM to implement the MP-FOC for the PMSM.The system model was built and simulated by Matlab/Simulink to verify the feasibility of the proposed scheme.Based on dSPACE,the corresponding peripheral hardware circuits are designed for the PMSM experimental platform in this paper.The experimental platform of the PMSM drive system based on two-phase three-phase inverter feeding is used for experimental verification of the MP-FOC.Meanwhile,the FOC experiments are used to conduct comparative analysis and research to demonstrate the feasibility,correctness and accuracy of the MP-FOC proposed in this paper.The experimental results show that the proposed scheme has the advantages of simple parameter setting,no overshoot,fast current response,avoiding the problem of dq axis current coupling and multi-step predictive control.So the MP-FOC has the higher control accuracy compared with the FOC based on the PI controller.