工艺控制卡的电磁兼容设计

Electromagnetic compatibility designing forswitching control card on automatic welding machine

针对外界电磁骚扰源引起的对系统的骚扰,或系统内部的PCB布线不合理而引起的电磁干扰问题,自动焊机工艺控制卡以电磁兼容的方法进行设计.自动焊机工艺控制卡的各个部分(开关量的输入输出、模拟量的输入输出和系统的内部)受到的干扰不同:前两者的信号量受到外界干扰的影响较大,应在输入输出口之间加入光电耦合器;后者应着重考虑元件摆放及其PCB布线.信号量的不同所选择的光电耦合器也有所不同.给出了用于模拟量的线性光耦LOC110的测试数据,表明用线性光耦能有效减少电磁干扰,维持信号量的基本形状.

Switching control card of automatic machine is usually designed in electromagnetic compatibility method .However,different disturbance source interferes the working of the switching_control card. There are 3 different disturbance sources in the design.Consist in the switch part between input and output,the analog part between input and output,and the internal system of the control card .It is recommended that the two formers should add the opto_coupler between input and output while the final should give emphasis to the displacement of electromagnetic elements and its PCB.Different opt_ocoupler should be used if signals were different.The reducing disturbance is explained with the test data of linear opto_coupler LOC110.Finally the causes of EM1 are found and settled.