Research On Dual-Vector-Based Predictive Current Control Of Permanent Magnet Synchronous Motor Drive System

Model predictive control(MPC)for permanent magnet synchronous motors(PMSM)has the advantages of simple structure,fast dynamic response,and ability to handle multi-objective optimization.It is considered as a new generation of high-performance control strategies.The steady-state performance of the dual-vector-based model predictive current control(PCC)is higher than that of the single-vector-based PCC,and the switching frequency is lower than that of the three-vector-based PCC.It is a better control method,but there are still problems such as a large amount of calculation and a complicated algorithm.This article researches the above problems and proposes corresponding improvement methods.Firstly,PMSM mathematical model and MPC pulse generation method are introduced.The single-vector-based PCC and dual-vector-based PCC are described in detail.The methods used in dual-vector-based PCC include expanding vector set,deadbeat control of q-axis current,and deadbeat control of q-axis current and d-axis current.Then,the improved dual-vector-based PCC is proposed.1)Aiming at the problem of large calculation amount of dual-vector-based PCC with deadbeat control of q-axis current,a method of mixed vector selection is proposed.The running state of the motor is determined according to the speed error.During transient operation,all candidate vectors are traversed.In the steadystate operation,the calculation amount is reduced by optimizing from three effective vectors adjacent to and coincident with the effective vectors applied at the previous time.After that,the first voltage vector is determined and the second voltage vector is set to zero vector.On this basis,the selection range of the second voltage vector is expanded to improve the steady-state performance.2)An improved overmodulation optimization method is proposed to solve the problem that the selected vector of dual-vector-based MPC is not the global optimum which affects the steady-state performance.The proposed method determines the optimal voltage vector according to the region of the ideal voltage vector,which improves the steady-state performance.In addition,the proposed dual-vector-based PCC has a better three-phase current balancing control effect than the dual-vector-based PCC with deadbeat control of q-axis current.3)An improved common-mode voltage suppression strategy is proposed to solve the problems of large calculation amount and complicated algorithm of the existing dual-vector-based MPC for common-mode voltage suppression.The proposed method discards the zero vector in order to suppress the common-mode voltage.Two effective voltage vectors adjacent to the ideal voltage vector are selected and their action time is calculated,which reduces the calculation amount and the complexity of the algorithm.Finally,the effectiveness of the proposed dual-vector-based PCC based on hybrid vector selection,dual-vector-based PCC considering overmodulation optimization,and dual-vector-based PCC considering common-mode voltage suppression were simulated and verified.The experimental platform of the PMSM speed regulation system is introduced,and some research contents are verified by experiment.