Research On Model Predictive Current Control Strategy Of Permanent Magnet Synchronous Motor

Permanent Magnet Synchronous Motor(PMSM)has been widely used in numerical control,aerospace,new energy vehicles and other fields by virtue of its small size and excellent torque performance.In parameter adjustment,the traditional PI control strategy has the disadvantages of difficult adjustment and mutual restriction between response speed and overshoot.In order to meet the requirements of PMSM speed control system control performance in different fields,it is necessary to study high-performance control strategies.In this context,in this thesis,the PMSM model predictive current control(MPCC)strategy is studied.Firstly,the structure of PMSM is analyzed,the mathematical models of surface-mounted PMSM in different coordinate systems is derived,and the PMSM vector control strategy is introduced,which lays the foundation for the model predictive control strategy.Secondly,aiming at the problem that the second voltage vector in the traditional optimal duty cycle model predictive current control(ODC-MPCC)is fixed to a zero vector,which results in poor steady-state performance,two control strategies are proposed.The first control strategy,in order to improve the steady-state performance of the system,an improved optimal duty model predictive current control(IOD-MPCC)strategy is proposed,that is,When the voltage vector is combined,the location of the optimal voltage vector at the previous moment is used as the candidate voltage vector at the next moment.The number of candidate voltage vectors is reduced from 6 to 3.In order to reduce the switching frequency of the system,unnecessary voltage vector combinations are screened,and the current is predicted 5 times.The second control strategy,aiming at the problem that the calculation burden of the IOD-MPCC has not been significantly reduced,the deadbeat concept is introduced into the i_q deadbeat control,and an MPCC with reduced computational burden(RCB-MPCC)is proposed.The second control strategy is subdivided into two control strategiesⅠandⅡaccording to whether the second voltage vector is fixed to zero.Then,using matlab/simulink simulation,the results show that the first control strategy has better steady-state performance than the traditional ODC-MPCC without affecting the calculation burden of the algorithm and the dynamic response speed of the system.In the second control strategy,compared with the traditional ODC-MPCC,the control strategy I reduces the computational burden by 66.67%,and the dynamic and static performance of the system has not changed.Compared with control strategy I,the control strategyⅡincreases the calculation amount by one time,but the steady-state performance of the system is improved.Therefore,compared with the traditional ODC-MPCC and the IOD-MPCC,the control strategy II has not only improved steady-state performance,but also reduced the computational burden,which is the optimal control in the proposed strategy.Finally,the RT-LAB platform is used to verify the optimal control strategy and the traditional control strategy.The experimental results prove the effectiveness and feasibility of the proposed algorithm.