Research On Driving Motor And Control Strategy Of Permanent Magnet Hybird Maglev Train

With the ongoing urbanization and the increasing city size, the Mid-low speed maglev train has become a new development aspect of maglev technology which can be used in urban rail transit system. Compared with the traditional electromagnetic maglev train, permanent magnet hybrid maglev train uses the long stator permanent linear synchronous motor (PMLSM) as its driving motor. The secondary poles of PMLSM consist of permanent magnet materials. This design has a lot of advantages such as reducing power consumption significantly, increasing air gap length, simplifying the structure of maglev system. In terms of performance and cost, permanent magnet hybrid maglev train has obvious advantage which gives it a broad prospects in the field of Mid-low speed maglev train. As one of the core technologies of maglev train, researching on the linear motor drive technology of permanent magnet hybrid Maglev train has a great realistic significance.To begin with, the main types and differences of the drive motor of maglev train are conduced in this thesis. And the working principle and characteristics of PMLSM used in M3maglev train is analyzed. The relationship between the horizontal thrust of driving motor and its major structural parameters has been thoroughly analyzed by analytical method and finite element method (FEM).Secondly, the causes of thrust fluctuation of the driving motor are studied, especially the effect of cogging effective and harmonic electromotive force (EMF) on the thrust fluctuation is in-depth analyzed. According to the theory of fractional-slot design for rotating motor, a fluctuation restraining method based on unequal polar distance design of PMLSM driving motor is applied. The analyzing results by FEM using Ansoft Maxwell show that the appropriate unequal polar distance design can restrain cogging force and harmonic EMF consequently.Finally Mathematics model of the drive motor in d-q coordinate system is established and the control strategy of driving motor are studied in the last chapter. After comparing the advantages and disadvantages of four different kinds of current control methods of vector control, the isd=0vector control is selected as the control strategy of the driving motor. In addition, a voltage feed-forward method and a sensor-less technology based on model reference adaptive system (MRAS) are studied and applied to the driving motor control system. The validity of the control strategy is verified by the simulation in MATLAB/Simulink.