开关电源近场辐射效应分析与模型研究

本文实验考察了一台功率因数校正器(PFC)主电路产生的辐射电磁场对传导干扰发射的影响,细致分析了PFC与EMI滤波器、电源输入线缆间的电磁耦合效应,在此基础上,建立了包含电场耦合效应的传导干扰电路模型并加以验证。基于电源共模传导干扰简化模型,提出了临界耦合距离概念并进行了实测,该参数可为开关电源早期阶段的EMC布局设计提供参考。最后,提出了几种辐射效应抑制新措施。

Near field effect analysis and common mode conducted EMI model of a switched mode power supply

In this paper,the electromagnetic near field coupling effects among a PFC power supply,an EMI filter and input power cord are studied by experiments and theoretical analysis in detail.Near field coupling nature and its influence positions are analyzed firstly.Then a Saber conducted EMI circuit simulation model of this power converter is built up and verified,which includes the electric coupling effect.After ignoring some small parameters in common mode EMI paths of this power supply,a simplified common mode EMI model is obtained and electric coupling influence is analyzed based on the model.Critical sensitivity coupling distance concept is then proposed and applied between this PFC and EMI filter.Its value can be obtained by approximated calculation or measurement and it is helpful for power supply EMC optimizing design in early stage.Finally,some novel coupling EMI control methods,such as relative angle arrangement,are proposed and verified.