Research On Model Predictive Current Control For Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor is widely used in high performance motor control system.As the innermost loop of the servo drive system,the performance of the current loop is the basis of the servo drive performance.Model predictive control has high dynamic control performance.The finite control set model predictive control has high dynamic response,but poor steady-state control performance and large computational load.The continuous control set model predictive control can achieve better steady-state control performance,but it needs to combine the method of space vector modulation to output voltage vector,and usually needs to combine the over-modulation algorithm to improve the voltage output capacity.Aiming at the problems existing in model predictive control,this thesis combines the advantages of traditional model predictive control methods to improve the model predictive current control method.In this thesis,the method of three-sector vector synthesis is derived,and then the model predictive current control is realized by calculating the phase voltage duty ratio.The three-phase voltage duty ratio can be obtained directly by predictive control,which can reduce the computational burden of predictive control compared with the original six-sector vector synthesis method.This method not only improves the steady-state control performance of the system,but also saves the space vector modulation and over-modulation algorithm.In addition,this thesis proposes a dead zone adaptive compensation algorithm based on model predictive control to solve the problem of low load control performance of model predictive control.This algorithm calculates the voltage vector for dead zone compensation through the prediction model,reduces the adverse effect caused by inaccurate judgment of current polarity in the traditional compensation scheme,improves the compensation accuracy,and reduces the phase current harmonic content.Combined with the two improved algorithms proposed in this thesis,the new model predictive current control scheme will greatly improve the predictive control accuracy and control performance under low speed and light load.In this thesis,the feasibility of the proposed scheme was verified by MATLAB/Simulink simulation software,and a physical experiment platform was built based on R5F562 TAANFP DSP chip to verify the feasibility and effectiveness of the proposed scheme.Compared with the traditional control method,the control effect of the proposed scheme is evaluated.Experimental results show that the proposed model predictive current control algorithm has good dynamic and steady-state control performance,and the adaptive compensation algorithm has good compensation effect,which greatly improves the current loop control performance.