Research On Direct Thrust Control Of Traction Linear Induction Motor

With the urban traffic congestion problem appears to be increasingly serious, our country enters into the peak period of the development of urban railway system. Due to its unique advantages, the railway system powered by linear induction motor has enjoyed widespread attention. The direct thrust control technology is highly appropriate for the control of traction motor in accordance with its simplicity of algorithms, the rapidity of dynamic response and the strong robustness to parameter change. This thesis use the short primary single-sided linear induction motor for urban rail transit train traction as the study object, and undergoes profound research on the operating characteristic and direct thrust control strategy of linear induction motor from the perspective of theoretical analysis and computer simulation. The main research contents are as follows:Firstly, this thesis conducts systematic analysis of linear induction motor edge end effect and vertical force. The transverse end effect and the first longitudinal edge side effect have slight influence on linear induction motor performance, whereas the second longitudinal edge side effect has much. In light of this, the mathematical model of rotating induction motor that amends no unit dimension of Q is introduced, and then the mathematical model of linear induction motor is derived.Secondly, with the linear induction motor electromagnetic simulation which taking the discontinueous of secondary plate at the turnout area into consideration built by way of Ansoft Maxwell software, this thesis elaborately analyzes the distribution situation of air gap magnetic field in conditions when linear induction motor primary partly into, fully into, partly leave and fully leave no induction plate area, and derives that linear induction motor will Lose thrust in no induction plate area which based on the study of control law of thrust and vertical force.Moreover, direct thrust control strategy which is suitable for the railway traction is studied. Through s function, the simulation model of mathematical model of linear induction motor is built in Matlab/Simulink software. Aiming at the existing observation error of flux linkage observer, the direct thrust simulation model is established after the amendment of observation error. Through the speed step simulation of linear induction motor with or without the consideration of the end effects, the validity of the motor model is verified. The speed and the thrust step simulation results to the control system of different flus observer show the validity of the control strategy.Finally, In the purpose of maintaining the total thrust stability when the mass transit vehicles pass by the turnout, taking the NO.4line of Guangzhou underground for example, and aiming at there is no secondary reaction plate on turnout, then established the motor model only included the primary and simulated the system with four motors, the result show that the total thrust maintains stable and avoid the loss of thrust when the mass transit vehicles pass by no induction plate area.