反激式开关稳压电源传导干扰研究

开关式直流稳压电源的电磁干扰不仅对电网产生干扰,导致在同一电网上供电的其它设备不能正常工作,而且严重的谐波电压电流会在开关电源内部产生电磁干扰,从而造成开关电源内部工作不稳定,使开关电源性能降低。文中以反激式开关稳压电源为研究对象,主要分析了传导测试中,差模、共模传导两种方式噪声源的产生机理,建立了开关电源传导干扰模型,采用EMI滤波器即共模滤波和差模滤波,并详细研究了加入π型滤波器、输入x电容、共模扼流圈等对开关稳压电源传导干扰的抑制效果,得出传导干扰抑制在标准限制范围的改进措施,整改后可让传导干扰强度从100μV降低到200 nV并通过认证。研究结果表明该措施对抑制开关稳压电源传导干扰是有效的。

Analysis of Conduction Interference of Flyback Switching DC Power Supply

The electromagnetic interference of switching DC power supply interferes with the power grid,resulting in the fact that other equipments in the same power supply line don＇t work normally,and electromagnetic interference generated in the switching modepower supply internally by the serious harmonic voltage and current leads to instability of the inner operation of switching mode power supply,thus decreasing the performance of switching mode power supply.This article makes a studying on the flyback switching mode power supply.It mainly analyzes the generation mechanism of noise sources in the conduction tests of common-mode and differential mode.It establishes interference model for the conduction of switching mode power supply,and employ the common-mode EMI filter and differential mode filter to make a detailed study of the join-type π filter,and the suppression effect of the conduction of switching mode power supply by inputting x capacitors,common mode choke,etc.Then,this thesis offers the measures of improvement by limiting the conduction interference within a standard boundary.The conduction disturbance reduces from 100 μV to 200 nV after renovation and is certified.The results show that the measures are effective to suppress conduction interference of the switching mode power supply.