IS200VAICH1DAB燃機(jī)通用卡件
對(duì)于繼電器未供電，常開(kāi)點(diǎn)已經(jīng)吸合的情況，即繼電器觸點(diǎn)短路失效，一般存在以下三種可能，下面對(duì)以下三種可能原因一一進(jìn)行分析排查：
1.繼電器動(dòng)作頻率過(guò)高，使用次數(shù)已超過(guò)繼電器所能承受的開(kāi)關(guān)次數(shù)；
2.繼電器所處環(huán)境溫度過(guò)高；
3.繼電器流經(jīng)浪涌電流過(guò)大。
IS200VAICH1DAB燃機(jī)通用卡件通過(guò)對(duì)圖1電路工作原理的分析和實(shí)際監(jiān)測(cè)繼電器K1觸點(diǎn)兩端電壓，繼電器K1僅在上電過(guò)程中動(dòng)作，正常工作后觸點(diǎn)不會(huì)再有開(kāi)關(guān)動(dòng)作，因此繼電器K1的開(kāi)關(guān)次數(shù)僅與人為輸入的開(kāi)關(guān)次數(shù)有關(guān)。通過(guò)查閱繼電器的規(guī)格書(shū)可知，該繼電器的使用次數(shù)為1*104次，產(chǎn)品還在調(diào)試階段，不可能達(dá)到1*104次，所以不是使用次數(shù)超過(guò)壽命的原因?qū)е隆！更S色為輸入電壓，藍(lán)色為繼電器觸點(diǎn)電流」
通過(guò)實(shí)際測(cè)量，如圖2，該繼電器工作時(shí)觸點(diǎn)電流約3A，繼電器環(huán)境溫度為83℃。查閱本款應(yīng)用的繼電器規(guī)格書(shū)標(biāo)明環(huán)境耐溫參數(shù)為10A/85℃，通入電流7A時(shí)可用于105℃，對(duì)比實(shí)際使用的環(huán)境和電流，可以排除由于使用環(huán)境溫度過(guò)高的原因?qū)е??！更S色為輸入電壓，藍(lán)色為繼電器觸點(diǎn)電流」
繼電器K1后端負(fù)載為感性負(fù)載(L1、L2)及容性負(fù)載（C1、C2、C8），實(shí)測(cè)繼電器K1觸點(diǎn)電流，如圖3所示。從圖中可以發(fā)現(xiàn)繼電器K1觸點(diǎn)在導(dǎo)通后的一段時(shí)間內(nèi)出現(xiàn)了尖峰電流，最大尖峰Imax=39.4A。繼電器規(guī)格參數(shù)最大耐電流10A，而在調(diào)試產(chǎn)品時(shí)經(jīng)過(guò)多次開(kāi)機(jī)產(chǎn)生的浪涌電流沖擊（39.4A）會(huì)使觸點(diǎn)處損傷進(jìn)而導(dǎo)致粘合失效。
03 繼電器吸合中出現(xiàn)浪涌電流的原因
通過(guò)排查，了解到繼電器觸點(diǎn)短路失效的原因是繼電器流經(jīng)浪涌電流過(guò)大，那么在圖1的電路中，是什么原因引起繼電器吸合中出現(xiàn)浪涌電流，對(duì)以下可能導(dǎo)致浪涌電流的器件進(jìn)行監(jiān)測(cè)和分析：
1）是否PFC電感L2飽和；
2）是否L1差模電感飽和；
3）是否π型濾波電容C1太大；
4）是否PFC限制鉗位電流太大。
principles of PCB design, and meet the requirements of anti-interference design.
1、 General principles of PCB design
In order to obtain the best performance of electronic circuits, the layout of components and wires is very important. In order to design PCB with good quality and low cost, the following general principles should be followed.
1. Layout of special components
First of all, we should consider the size of PCB: when the size of PCB is too large, the printing line is long, the impedance increases, the anti noise ability decreases, and the cost also increases; If it is too small, the heat dissipation is poor, and the adjacent lines are easy to be disturbed. After determining the size of PCB, determine the position of special components. Finally, according to the functional units of the circuit, all components of the circuit are laid out.
The following principles shall be observed when determining the position of special components:
① Try to shorten the wiring between high-frequency components and try to reduce their distribution parameters and mutual electromagnetic interference. Components that
