The Research On Direct Thrust Fuzzy Control Of Linear Induction Motor

With the linear induction motor (LIM) driven subway cars in the rail transportation plays an increasingly huge role, the control technology of the LIM is particularly critical. Since the traditional vector control has some shortcomings on engineering applications such as large of calculations, complex system structure, it has a great of significance on researching direct thrust control strategy which is applied to the LIM. The paper uses LIM as the control object, and research the control performance when the direct thrust control strategy is applied to the LIM.The edge effect cannot be ignored when the subway cars were driven by LIM. For the purpose, the paper proposed a new mathematical model of the LIM which was based on the edge effect. On this basis, the model of the LIM was simulated, and the results showed that the motor model more accurately reflected the characteristics of LIM which was used for urban rail transit. It provided a good research object for the control technology of the LIM.The paper carried out an in-depth analysis using simulated method on direct thrust control strategy which was applied to the LIM. The direct thrust control system had a faster thrust and velocity response, high robustness from the simulation results. However, there was a little thrust ripple in the control system. Focused on this problem, the paper used fuzzy logical algorithm, and put forward a new method based on fuzzy logical which was designed for reclassifying the error of the flux and the thrust. The thrust ripple due to choosing the same space voltage vector had been successfully solved.Comparison of the simulation results of the traditional direct thrust control system, the control system based on fuzzy logic decreased the thrust and velocity ripple obviously. It improved the output characters and the performance of the control system. The results also showed that the new model based on fuzzy logic has high value on engineering application.