Study On Electromagnetic Interference Of Intercity Train Vehicles To Axle Counter

With the rapid development of China’s modernization in the 21 st century and the rapid increase of urban population,urban rail transit has attracted more and more attention,and there is a huge demand in the future.Axle counter is an important detection equipment of urban rail transit,which plays a decisive role in the safety of railway operation.The traditional urban rail adopts DC power supply.In recent years,some new rail lines adopt 25 k V AC power supply.The addition of new power supply mode must be accompanied by the problem of electromagnetic compatibility between urban rail systems.At present,the axle counter in some lines is subject to electromagnetic interference during train operation,which seriously affects the normal operation of the train and personnel safety.Therefore,it is necessary to study the electromagnetic compatibility between the new urban rail train and axle counter.Most of the research on EMC of axle counter at home and abroad mostly focuses on the electromagnetic characteristics of axle counter itself,and the object is DC powered vehicles;At present,a few studies on electromagnetic compatibility of vehicle and axle counter system under AC 25 k V power supply system focus on testing,and there is no systematic simulation modeling research on vehicle and axle counter,and there is no systematic analysis on its interference mechanism and interference path.There are still deficiencies in the systematicness and depth of the research.Therefore,the research on the electromagnetic interference of intercity train vehicles on axle counters has important theoretical significance and practical value.Aiming at the common transient conditions of operating circuit breaker and the steady-state conditions of normal operation of traction system of a certain type of urban rail vehicle,this paper takes the axle counter as the research object,analyzes the electromagnetic interference mechanism of vehicle to axle counter,establishes the system level electromagnetic compatibility simulation analysis model of vehicle and axle counter,and verifies the accuracy of the model through the test of existing vehicles,The interference characteristics of the operating overcurrent of the circuit breaker and the conducted current of the traction system on the axle counter are analyzed,and the interference amount to the axle counter is predicted.On this basis,the research on the suppression technology of the interference of intercity trains on the axle counter is further carried out,so as to provide simulation assistance and guidance for the EMC design and rectification of intercity trains and axle counters.The research results of this paper show that under the condition of circuit breaker closing,the interference current in the working frequency band of axle counter is mainly distributed on the grounding wire of transformer and the grounding wire of shielding layer of high-voltage cable,and the interference current component of high-voltage cable path is about 20 d BA larger than that of transformer grounding wire,Therefore,the overcurrent generated by the closing of the circuit breaker mainly enters the rail through the high-voltage line and interferes with the axle counter through the rail radiation;In the worst case,the magnetic field intensity of axis Z at the position of axle counter exceeds its interference limit by about 16 d B;Under the traction operation condition of intercity train,the component of the interference current caused by the vehicle traction system in the working frequency band of axle counter on the path of high-voltage cable is about 40 dba less than that on the grounding wire of transformer.Therefore,the interference generated by the traction system mainly enters the steel rail through the working grounding of transformer,and then returns to the interference source through the protective grounding of vehicle body,In the worst case,the magnetic field intensity of axis Z at the position of axle counter exceeds its interference limit by about 7d B;In order to suppress the electromagnetic interference of intercity trains to the axle counter,this paper proposes a shielding structure that can be used for the axle counter head.Based on the established simulation analysis model of the axle counter head and shielding structure,the interference suppression effect of about 3.2db is realized in the working frequency band,and the working signal of the axle counter is basically not affected.