频率调制抑制DC／DC变换器EMI的研究

开关电源是采用高速半导体器件来进行电能转换的，开关切换过程中产生的电压电流尖峰造成了严重的EMI问题。常规的DC／DC变换器工作在频率固定的PWM模式下，频谱是离散的，开关频率和低次谐波的能量尖峰很高。文章研究了频率调制技术抑制DC／DC变换器EMI噪声的效果，通过对一台Boost变换器样机进行周期频率调制，证明了频率调制技术对抑制DC／DC变换器EMI的有效性。

Study on DE/DE Converters EMI Suppression by Frequency Modulation Technique

In switching mode power supply, voltage or current transformation for power conversion is conducted by semiconductors and the high voltage spike and current spike produced in the process of switching cause serious EMI problems. Ordinary DC/DC converters work under the fixed switching frequency mode, so the spectrum is discrete and the energy concentrate at the low frequency. Frequency modulation（FM） technique in DC/DC converter EMI suppression is studied in this paper. By modulating a Boost converter with periodic signal, the spike of spectrum is significantly lower down, and the EMI suppressing effect is proven.