基于容性耦合的钢轨压力传感器电磁干扰分析

The electromagnetic interference analysis of rail pressuresensor based on capacitive coupling

目前随着弱电装置在铁路通信、传感测量等方面的普及,电磁干扰问题越来越引起人们的重视,但是关于电磁干扰机理的耦合分析等方面的工作开展较少。本文针对一则典型的钢轨压力传感器电磁干扰问题,从干扰源排查入手,建立了电源线与信号线的容性耦合物理模型,提取线缆间分布电容参数,定量分析了耦合电场大小;同时找出干扰源,确定为电源线容性耦合导致的串扰电压干扰,给出了相应抑制干扰的措施,该分析与实测相符合。研究结果表明,接地装置对电源线地线的电磁干扰影响很大,从而进一步影响了信号线的信号电压。当接地电阻的埋入深度从0.1 m增加到0.6 m时,电源线的干扰电压得到了抑制;信号线的连接端头是容易耦合到外界电磁干扰的薄弱环节,是改善屏蔽效能的关键点。本文所提出的关于容性耦合的机理分析、计算方法、以及传感器信号的电磁干扰抑制措施,能够为今后电气设备的电磁干扰分析抑制提供普遍的借鉴意义。

Nowadays,with the popularization of low current device in railway communications,sensors and other aspects,electromagnetic interference has attracted more and more attention,however,the work about the coupling analysis of electromagnetic interference mechanism is rare.This study focuses on a typical electromagnetic interference problem of rail pressure sensors.First a physical model of capacitive coupling between power and signal lines is established based on the investigation of interference sources.Then the distributed capacitance parameters between cables are extracted,and the value of coupling electric field is quantitatively analyzed.At the same time,the interference source is identified and the capacitive coupling voltage interference caused by power line crosstalk is determined.Corresponding measurements of suppressing interference are provided,which verifies the analysis.The results show that the grounding device has a great influence on the electromagnetic interference of signal voltage.When the buried depth of the grounding resistance increases from 0.1 m to 0.6 m,the electromagnetic interference voltage of the power line is suppressed.Furthermore it′s found that the connecting end of signal line is a weak link valuable to the electromagnetic interference,which is the key to improve the shielding efficiency.The mechanism analysis and calculation method of capacitive coupling proposed in this paper and the suppression measures of electromagnetic interference of sensors can provide a general reference for suppressing the electromagnetic interference of electrical equipment in engineering.