Model Predictive Current Control Stratery For Permanent Magnet Synchronous Motor Drive System

The permanent-magnet synchronous motor(PMSM)drive system fed by a voltage-source inverter(VSI)has a lot of merits,such as simple structure,good reliability,and highpower density,etc.It has been applied in various industrial fields including aviation,rail traction,and so on.Model predictive control is a kind of online optimal control algorithm which is produced in industrial process control.It shows great advantage in dealing with complex constrained optimization problem of nonlinear system.In recent years,the model predictive control has the advantages of fast dynamic response,flexible configuration of the objective function,easy to handle constrained optimization problems,and has been widely used in the field of electric drive.But,the traditional model predictive current control exist two problem that the number of voltage vectors are limited and dutycycle modulation can't be used effectively.Aiming at two problems,this paper carried out relevant research work.In this paper,a predictive current control based on the operating time of vector is proposed for voltage source inverter(VSI)–permanent magnet synchronous motor(PMSM)drive system.The steady state performance of the system is improved by extending the finite control set and changing the selection method of the optimal voltage vector.Firstly,the finite control set(FCS)is extended by adding the virtual voltage vectors and optimized according to the different increasing and decreasing effects of vectors on the d-axis current in each sector.Then making the predictive d,q-axis current values of next time equals to their expected values,so the d,q-axis operating time of each vector are obtained separately.The d,q-axis operating time of each vector are used to evaluate the action effects on d,q-axis current,which replaces the predictive current part in the traditional model predictive current control.Meanwhile,depending on the operating time of vector to select the optimal voltage vector,the proposed method can solve the problem that the duty cycle doesn't work effectively in the redictive current control with duty cycle modulation.Finally the experimental verification of the traditional one vector model predictive current control,one active vector and zero vector modulation model predictive current control and the proposed methed in this paper are comleted in the two level inverter control system of permanent magnet synchronous motor.The steaty experimental results show that the proposed algorithm can effectively solve the question that the duty cycle modulation link can not be effectively used.Meanwhile,the dynamic experimental results show that the proposed algorithm has the same dynamic response speed as the traditional model predictive current control method.