Research On Application Of Direct Torque Control Of Interior Permanent Magnet Synchronous Motor In Rail Traction

In recent years,Permanent Magnet Synchronous Motor(PMSM)has attracted more and more attention in rail traction system because of its simple structure,high power density and low operating noise,which the advantages of the built in IPMSM.Commonly using motor control strategies are Field Oriented Control(FOC)and Direct Torque Control(DTC).Only through the controlling of torque angle,the direct torque control can e asily control the torque speed,Simple and does not require complex decoupling operations and less depends on the parameters.Firstly this paper introduces the development history of rail traction system,the research status and development trend at home and abroad.Then,the basic mechanism,working principle and mathematical model of the built-in PMSM are analyzed and studied,and the DTC system of PMSM is built in Matlab / Simulink.In order to overcome the shortcomings of the switching table in the traditional control method,the Space Vector Pulse Width Modulation(SVPWM)method is used to replace the switch table,which improves the accuracy of the system and reduces the pulsation of the system.Matlab/Simulink,a model of SVPWM based on PMSM-DTC system is built.In order to enhance the anti-jamming and robustness of the system,this paper introduces the second-order sliding mode theory,the super-twisting algorithm and the Matlab/Simulink simulation.The simulation results show that the system can obviously reduce the torque and flux fluctuation,improving the stability of the system,showing strong robustness to the torque mutation.However,due to the influence of stator resistance factor,the stator flux observation error is huge at the beginning of the system operation.To reduce the influence of flux linkage caused by stator resistance,this thesis will launch the on-line estimate on stator resistance to effectively weaken pluse.