开关频率抖动技术中调制波优化选取的理论分析

本文采用解析式的方法描述开关频率抖动的过程，对三种常用的正弦波、三角波及指数波在调制正弦载波信号时产生的频谱结构进行详细的计算和分析，得出采用三角波调制可以产生最优的频谱峰值幅度衰减。总结产生不同频谱结构的现象和原因，以此预测任意周期性调制波形对PWM载波调制后的频谱结构，有助于在应用开关频率抖动法降低变换器电磁干扰时调制波形的优化选取。

Theoretical Analysis of Selection for Optimal Modulating Waveform Applied in Switching Frequency Jitter

An analytic formulation method is used for expressing the process of the jittering switching frequency. The spectrum of sinusoidal carrier modulated by three common modulating waveform is calculated in detail and the optimal triangular waveform is derived. The phenomena and wherefore of the modulating result are summarized to predict the effect of amplitude reduction of the spectrum of PWM signal modulated by arbitrary waveforms. These rules of selection for the periodical modulating waveform is useful for when adopting the method of switching frequency jitter to reduce the EMI of the converter.