离线式PWM开关电源传导电磁干扰的分析研究

该文利用分析和测量相结合的方式，详细研究了一台离线式PWM开关电源的传导电磁干扰(EMI)特性。在分析各个器件作用的基础上，得出了反映典型电磁干扰发射时，传导干扰发射量、干扰源和干扰传播通道关系的线性化方程，进而提出了测量典型传导干扰耦合通道特性的新方法，并进行了验证。利用测得的传导干扰耦合通道特性，具体分析了PWM开关电源高频功率开关器件中dv/dt,di/dt对传导干扰发射的作用。根据变换器主要的杂散参数和共模干扰的基本传播途径，可得出低阶的等效共模传导干扰模型，以指导电源滤波器的设计。

RESEARCH ON CONDUCTED EMI OF AN OFF-LINE PWM SWITCHED MODE POWER SUPPLY

In this paper, the conducted EMI characteristic of an off-line PWM power supply is analyzed in detail. Considering the high frequency switches as main EMI sources, a group of simple equations can be deduced, which describe the typical relationship among EMI emissions, the noise sources and the coupling paths. Based on the equations, a novel measurement is proposed to characterize the conducted EMI coupling paths. According to the equations and the characteristics of the coupling paths, the different roles of dv/dt and di/dt in high frequency switches on conducted EMI emissions can be analyzed concretely. An equivalent common mode conducted EMI model is built according to the basic coupling paths and the main stray parameters of the converter. This model avoids complicated stray parameters extraction process and is useful for the design of EMI filter.