反激式开关电源的电磁干扰建模及抑制方法分析

EMI modeling and suppression method analysis of flyback switching power supply

开关电源在众多领域已被广泛应用,开关电源的高频特性导致了严重的干扰问题。若在设计时能够明确单一元件和EMI的关系,在此基础上经参数控制达到开关电源的EMI控制,将对开关电源的开发设计起到巨大的作用。本文将以反激式开关电源的EMI建模及抑制方法分析作为切入点,对变压器的等效模型进行分析,得出变压器寄生电容对骚扰电压的影响机理,提出一种通过外加电容来补偿变压器寄生电容的EMI抑制方法,并对该方法的有效性进行实验验证。

Switching power supply has been widely used in many fields, and the high frequency characteristics of switching power supply lead to serious interference problems. If the relationship between single component and EMI can be made clear in design, and then EMI control of switching power supply can be achieved by parameter control, it will play a great role in the development and design of switching power supply. In this paper, the author takes EMI modeling and suppression method analysis of flyback switching power supply as the breakthrough point, analyzes the equivalent model of transformer, obtains the influence mechanism of transformer parasitic capacitance on disturbance voltage, proposes an EMI suppression method to compensate transformer parasitic capacitance by adding capacitance, and verifies the effectiveness of this method by experiments.