Permanent Magnet Synchronous Motor Model Predictive Control Based On Urban Rail Traction System

With the urbanization rate is increasing year by year,the urban traffic situation is becoming more and more serious.Because of its high reliability,large passenger turnover and strong anti-interference,urban rail traffic has become a good medicine for cracking down on urban denounces.The traction control system of urban rail is an important configuration of urban rail transit equipment.The permanent magnet synchronous motor(PMSM)has been successfully applied to the traction control system of urban rail with the advantages of small size,great power factor,high efficiency and reliability.In order to promote the theoretical research and application of permanent magnet synchronous motor traction system for urban rail vehicles,this dissertation analyzes the research status at home and abroad.With the traction system of urban rail transit as the subject background,the interior permanent magnet synchronous motor as the research object,the dissertation proposes model predictive torque control method of permanent magnet synchronous motor based on MTPA to improve the shortcomings of large torque ripple and poor robustness of direct torque control.Mainly includes the following aspects of the research content:(1)The cost function control goal of traditional finite set model predictive control is single,which can't play the advantage of model predictive control rolling optimization effectively,and it also has the shortcomings of unstable switching frequency and poor dynamic response.Therefore,the cost function of multiple control objectives can be constructed in this dissertation,for example,the minimum torque error,the maximum torque per ampere control and the current constraint condition,in addition,the Lyapunov function is constructed to calculate the duty cycle of each space voltage vector in the finite set for further optimization.(2)According to the working characteristics of stator current vector in different operation areas,the finite set model predictive control algorithm is applied to flux-weakening control.The flux-weakening control is realized by introducing the penalty function of the voltage constraint conditions and maximum torque per voltage control in the cost function to meet the requirements of the wide speed range of the urban rail traction system.(3)The simulation models of direct torque control,traditional finite set model predictive control and forward finite set model predictive control algorithm are built in Matlab/Simulink environment.The steady and dynamic characteristics of the three control algorithms are compared and analyzed by simulating the load variation and acceleration / deceleration conditions of urban rail traction system,at the same time,the influence of different parameters(such as stator resistance,flux and dq-axis inductor)on the three control strategies is analyzed.Simulation results show that the improved finite set model predictive control has a long acceleration and deceleration time,but it has the advantages of small torque ripple,fast dynamic response and strong robustness.Finally,the permanent magnet synchronous motor flux weakening control model based on finite set model prediction is built,and the effectiveness and feasibility of the algorithm are analyzed.