车联网系统中电磁干扰问题分析与优化

Analysis and optimization of electromagnetic interference in vehicle networking system

针对车联网系统中电磁干扰不合格的问题,基于系统架构和测试设计方案分析频点超标的具体原因,将骚扰源定位在开关电源和语音芯片内部的锁相环倍频上,并根据原理图和布局布线提出抑制传导干扰和辐射干扰的优化措施,对开关电源采用RC吸收电路解决与噪声不匹配的问题,对于语音电路采用对高频噪声吸收较好的磁珠和共模滤波器等用于抑制噪声,结合π型滤波器电路降低噪声的峰值。经过优化后的方案复测已满足认证标准要求,并且配合整车联调测试通过EMC的标准,满足了整车使用的可靠性要求。

In view of the unqualified electromagnetic interference in the Internet of vehicles system,based on the system architecture and test design scheme,analyze the specific reasons for the frequency point exceeding the standard. The disturbance source is located on the PLL frequency doubling inside the switching power supply and voice chip,and put forward the optimization measures to suppress the conductive interference and radiation interference according to the schematic diagram and layout and wiring,RC absorption circuit is used for switching power supply to solve the problem of noise mismatch,magnetic beads and common mode filter with good absorption of high-frequency noise are used for speech circuit to suppress noise,and π filter circuit is combined to reduce the peak value of noise. The retest of the optimized scheme has met the requirements of certification standard,and passed the EMC standard in coordination with the vehicle joint commissioning test, meeting the reliability requirements of the whole vehicle.