随机频率调制降低电磁干扰的调制信号类型比较研究

摘要

Reduction of conducted EMI noise in switching power converters using random frequency modulation 9cheme (RFMS) was proposed. The principle of suppressing EMI noise under RFMS was analyzed briefly and an experimental prototype of the flyback converter was constructed. The power spectral densities of the MOSFETs current and the conducted EMI test results were presented under different random modulating signals. The experimental results demonstrate that both modulating signals can reduce the peak level of the switching harmonics effectively and the modulated result of the uniform distribution modulating signal is better than that of the normal distribution modulating signal.%利用随机频率调制技术从噪声产生源头上降低了开关变换器的电磁干扰.分析了具有不变概率密度分布的离散随机信号频率调科降低开关变换器EMI噪声的原理,并试制了一台随机频率调制开关变换器电源样机.比较了不同随机调制信号情况下开关管电流信号的频谱以及传导干扰测试的结果.实验结果表明,两种调制信号均能有效降低开关谐波峰值,但是均匀分布随机信号的调制效果优于正态分布随机信号的调制效果.