Research On Characteristics Of Linear Synchronous Motor For High-speed Maglev Train

As a new type of non-contact ground transportation,high-speed maglev train is mainly used to solve people’s demand for fast and easy travel.Linear synchronous motor is the key structure to realize the traction and levitation of maglev train.Its performance determines whether the train can run smoothly and safely.In order to analyze the output performance of the linear synchronous motor,this thesis separately studied the influence of different parameters on the electromagnetic characteristics based on the finite element analysis method.Considering the loss of the motor,the temperature rise of the stator core is also analyzed.Combined with the actual power supply situation of the linear synchronous motor,a field and circuit coupling model is established based on inverter power supply to analyze the influence of different fault conditions on electromagnetic forces and motor temperature rise.Firstly,according to the structure of high-speed maglev train,the finite element simulation model of linear synchronous motor is established,which is used to calculate the distribution of magnetic field at different running time and to discuss the distribution of magnetic flux density in suspension gap simultaneously.Based on the 2D finite element simulation model,the traction and levitation forces are calculated and their results are compared with the actual test data of the test sample vehicle under the conditions of speed 50km/h and 40km/h.The results confirms that simulation model can be used to calculate the motor approximately.Secondly,the influence of different parameters on the electromagnetic performance of the linear synchronous motor is analyzed,which contains traction force,levitat ion,electromotive force and core loss relying on the changes of stator current,excitation current,levitation gap length,power angle and running speed respectively.Then,considering the influence of the loss caused by the large current of stator windings on the temperature rise,a three-dimensional temperature field model based on finite element method is established to analyze the whole region temperature distribution of the stator.Meanwhile,the temperature changes of each structure are calculated.By investigating the temperature changes of the stator under different operating speeds,it proves that the stator insulation meets the temperature rise requirements under high-speed operation conditions.Finally,a field-circuit coupling model of the linear synchronous motor is established based on the SPWM control mode,and the influence of the different carrier wave ratio and modulation on the stator input current,the traction force and levitation force is analyzed.In addtion,the transient current changes are investigted after stator winding having a single-phase grounding fault or inverter having faults respectively,and the influence of fault on electromagnetic force and motor temperature rise is analyzed.In the above analysis,inverter faults include single power device open circuit fault,single-phase bridge open circuit fault and single power device short circuit fault.According to the simulation results,the influence of various faults on the fluctuation of traction force and levitation force is analyzed...