Research On Control Of Doubly-fed Linear Motor Based On Mover Current

In recent ten years, China's rail transit has made great progress. With the economic development, the major cities have new requirements of rail transport like the subway, maglev train, light rail, tram and so on. This paper mainly studies doubly feed linear motor (doubly feed linear induction motor) for urban rail, and the mathematical model of the motor, the vector control method based on the mover current, the end effect of the linear motor, the adjustment principle of the energy in the running and so on have been studied deeply.In this paper, the structure of the doubly-fed linear motor is analyzed. Compared to the single-side linear induction motor, the structure of the doubly-fed linear motor is obviously different. In order to construct the motor model accurately, it is needed to correct the edge effect coefficient. The one-dimensional electromagnetic field analysis method of the linear motor is used to derive the air-gap magnetic field expression of the motor, and then the longitudinal dynamic effect coefficient is deduced according to the relationship between the electromagnetic power inside the motor, and obtains the "T" equivalent circuit. The main performance parameters of the motor were calculated. The equivalent circuit provides a model basis for subsequent motor performance analysis and control.The finite element simulation is carried out using Ansoft Maxwell software. In the simulation, the excitation current, the air gap size and the running speed of the motor are mainly changed, and the change of the horizontal thrust of the motor under different conditions is studied, compared with the calculated value of the equivalent model to verify the validity of the model.According to the basic principle of the motor, the mathematical model of the motor under the synchronous rotating coordinate (dq0) system is established, the characteristics of the common control methods of doubly-fed machine are briefly analyzed, and the control method based on the mover current is decided. The whole control system is simulated by MATLAB /Simulink, and the effectiveness of the mover current control scheme is verified. The energy flow relation in the speed regulation of the doubly fed linear motor is studied. It can be seen from the analysis that the application of voltage with different amplitude and phase can change the motor speed, adjust the motor power factor, the direction of flow of energy can be judged by the phase angle difference between the respective voltage and current of the stator and the mover.