Research On Predictive Control Strategy Of Electrical Locomotive Traction Motor

Predictive control is a control method with a simple structure,easy to deal with multi-variable and multi-constraint problems,and has excellent dynamic response capability.It has been widely used in the field of power electronics.Compared with vector control,predictive control does not have proportional and integral structure,and has stronger dynamic response capability.Compared with direct torque control,the selection of the optimal voltage vector is more accurate.Based on the above advantages of predictive control,this paper takes PMSM as the research object,and makes a detailed research on the application of predictive control strategy of electrical locomotive traction motor.The main contents are as follows:Based on the model predictive control,a low switching frequency predictive control based on boundary circle confining strategy is studied.Aiming at the problem that the current vector cannot always be controlled within the boundary by changing the switch state when the current vector reaches or exceeds the boundary,and an improved boundary current error prediction strategy is studied.This improved strategy control the current vector within the boundary by switching the switch state one control cycle in advance.Aiming at the problem of weight contradiction of the optimization criterion and the large amount of computation,a control method based on adjacent vectors is studied,and the average switching frequency is further reduced.The detailed comparisons of current harmonics,average switching frequency and dynamic response capability with vector control are performed,through which the effectiveness and superiority of predictive current control are validated.Based on the deadbeat control,deadbeat direct torque and flux control which requires the modulation is studied.Compared with the model predictive control,this method has less computation and lower control frequency.At the same time,the Gopinath flux observer was studied so as to accurately obtain the necessary flux variables and torque variables in the control process.In order to verify the superiority of deadbeat direct torque and flux control in dynamic performance,a detailed comparison is made between deadbeat direct torque and flux control and vector control through simulation and experiment.Finally,through Matlab/Simulink software and towing experiment platform of PMSM,the strategies in this paper are simulated and experimentally verified.Simulation and experimental results prove the effectiveness and correctness of the algorithm.