Research On The Traction Control System Of Linear Induction Motor For Medium And Low Speed Maglev Train

The medium and low speed maglev train has begun to be promoted in use because of its advantages in low noise and strong gradeability. As the driving motor of the medium and low speed maglev train, the linear induction motor (LIM) is similar to asynchronous motor in operating principle. But the edge effects and normal force impact directly tractive performance and suspending stability. Therefore traction control system is researched intensively. Based on the analysis of linear induction motor’s electromagnetic properties, the thesis researched the traction system applicable to the medium and low speed maglev train.First of all, the thesis researched the electromagnetic properties and the edge effects of LIM by the distributed parameter electromagnetic theory and the lumped parameter equivalent circuit. The T-type equivalent circuit considering the edge effects was built. The physical model of LIM was built in the finite element analysis software Ansoft Maxwell 2D to analyze the relations between thrust, normal force and slip, current magnitude, slip frequency, running speed, air gap length. Through comparative analysis, the constant slip frequency control was adopted and the constant slip frequency to achieve the optimal control of electromagnetic force and normal force was worked out.Then, the thesis adopted the SVPWM modulation after analyzing its principle, algorithm and advantages. The mathematical model was established on the dq synchronously rotating coordinate system. The constant slip frequency vector control was adopted to control LIM in Simulink. The simulation results proved that the control system could achieve the optimal control of electromagnetic force and normal force. It made the normal force small within a tight band, electromagnetic force constant and the system have a good performance in transient response.Finally, the thesis established the LIM traction system and software to control the system. The train running test was completed in the test site of Southwest Jiaotong University Changzhou Institute of Rail. The results showed that the designed traction system was reasonable and the control scheme was simple and reliable. The normal force has little effect on the magnetic suspended system, and the traction system and magnetic suspended system ran stably.