Typical Electromagnetic Interference Of Maglev Vehicle PIS System Coupling Mechanism And Suppression Study

At present,there are few researches on electromagnetic compatibility of medium and low speed maglev vehicle in China,and many studies are based on foreign software.In order to solve the typical EMI problem of liquid crystal display(LCD)snowflake failure in the passenger information system(PIS)of medium and low speed maglev vehicle,in accordance with the usual thinking of dealing with EMI problems,that is,"the check of EMI source and coupling path--the analysis of the formation mechanism of EMI--the establishment of measures for solving EMI",a detailed study was carried out.First of all,the working principle and magnetic field distribution of the suspension electromagnet in the suspension system and the linear motor in the drive system are summarized.Based on the Maxwell 3D finite element simulation software,the simulation model of the suspension module and the linear motor is built.The magnetic field intensity distribution of suspended electromagnet coil,track,yoke and linear motor is studied,which lays a foundation for subsequent analysis of the interference source of the LCD fault in the PIS system.Then,the function and working principle of vehicle PIS system are analyzed,and the fault phenomenon EMI LCD screen is summarized.Based on theoretical analysis and simulation calculation,two kinds of interference sources,suspended electromagnet and collector boots,are excluded.At the same time,it is concluded that the transverse end effect of linear motor leakage magnetic field is the main interference source causing the fault of LCD screen,and its coupling way is inductive coupling.With the help of finite element simulation software,the inductive voltage generated in the closed loop connected between the LCD screen and the control system is calculated.The EMI coupling mechanism is analyzed by comparing the induced voltage calculated by simulation with the voltage tested by oscilloscope.As a result,the transverse end effect of the linear motor will cause the LCD shell grounding potential to rise,resulting in fine lines and even snowflakes on the screen.Finally,the solution of EMI problem is introduced,and four kinds of interference suppression measures are classified.On the basis of the actual situation of the vehicle,considering the improvement of the anti-interference ability for the LCD equipment,a scheme of using models of transient voltage suppressor(TVS)to discharge accumulated charge of the equipment is proposed.The above scheme is verified.The results show that the above suppression scheme can effectively eliminate the interference phenomena LCD flower screen and flash screen in the vehicle PIS system,make the interference waveform disappear and ensure that the LCD function is normal during the vehicle operation.