| Since the 21st century,with the continuous expansion of China’s urbanization process,urban rail transit has been developed rapidly in China.Maglev transportation using SLIM as traction motors has also achieved breakthrough results from scratch.However,in actual projects,short-primary maglev transportation exposes many technical problems in the fields of shoe-track flow,vehicle weight reduction,and vehicle speed increase due to the short application time.Professor Li Qunzhan from Southwest Jiaotong University proposed a four-track power supply control system for short-primary maglev trains that not only optimizes and solves existing engineering technical difficulties,but also performs very well in other performances.This article takes the four-track power supply control system of the short-primary maglev train as the guide,and launches a series of analyses.First,this article compares the advantages and disadvantages of the short-primary and long-primary maglev transportation systems from the vehicle system and the power supply system.According to the four-track power supply control system of the short-stator maglev train,a three-phase power supply short-stator maglev train scheme is derived,and the composition and operation mechanism of the power supply system and the traction control system are analyzed.Secondly,the power rail plays the role of traction backflow in the scheme.Considering the characteristics of its irregular cross-sectional shape,the electromagnetic field finite element method is used to analyze the electrostatic field and eddy current field of the power rail.The frequency variation characteristics of the corresponding electrical parameters per unit length are studied,and the equivalent radius of the power supply rail is determined.Combining with the Carson method,which is suitable for calculating the electrical parameters of circular cross-section conductors,the transmission line matrix of the power supply rail system is derived.Then,the SLIM dynamic mathematical model was established by using the eddy current theory.The space vector model of the power rail and SLIM in the synchronous rotating coordinate system is derived,and the SLIM constant slip frequency control strategy is studied.Aiming at the disadvantages of reduced control performance caused by changes in electrical parameters of the power supply rail system,vector control based on speed loop feedforward and current loop decoupling compensation and vector control based on a composite sliding mode variable structure current controller are proposed.Finally,taking a maglev test line as an example,the train traction calculation method suitable for this scheme is used to study and calculate the position of the following train points on the line and the performance parameters of the traction substation;in terms of train traction control,simulation compares The slip frequency,the constant slip frequency based on the speed loop feedforward and current loop compensation,and the three vector control strategies based on the composite sliding mode current controller verify the constant slip of the proposed composite sliding mode current controller The frequency vector control strategy is decoupled and robust,and meets the requirements of safe operation of maglev trains. |
