抑制汽车点火系统电磁干扰的光电隔离方法

The optical isolation method of suppressing electromagnetic interference of automotive ignition system

汽车发动机点火系统工作时产生的电磁辐射是车内最强的电磁干扰源,也是造成大多数电控单元(electrical control unit,ECU)误动作的主要原因。为了减小点火噪声对ECU的干扰,采用光电隔离技术来实现干扰源与控制电路的电气隔离。在分析点火系统电磁干扰形成机理的基础上,探讨了光电隔离技术抑制点火系统电磁干扰的可行性,设计了抑制点火系统电磁干扰的平台实验电路。实验结果表明,光电隔离电路在20～100MHz频段抑制点火噪声效果明显,在解决汽车电磁兼容问题上是可行的。

Electromagnetic radiation,which is caused by the engine ignition system,is the most powerful electromagnetic interference（EMI） source in the vehicles,as well as the main reason of most electronic control unit（ECU） malfunction.In order to reduce interference from ignition noise on ECU,we use optical isolation technology to isolate electrical connections between the interference source and the control circuit.The formation mechanism of the ignition system EMI is analyzed.The possibility of suppressing ignition system EMI with optical isolation technology is discussed.Then,as a result we design an experimental platform of suppressing ignition system EMI.The experimental results show that the effect of suppressing ignition noise,in 20~100 MHz frequency band,is obvious after applying optical isolation circuit.It can address the issue of automotive EMC.