【摘要】 利用频率调制技术从噪声产生源头上降低了开关电源传导电磁干扰。分析了频率调制降低EMI噪声的原理,并试制了一台周期频率调制反激变换器电源样机。比较了不同周期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,但是三角波调制信号的扩频效果优于正弦波调制信号。更多还原

【Abstract】 Reduction of conducted EMI in switching power supplies by using frequency modulation scheme (FMS) was proposed. The principle of suppressing EMI noise under FMS was analyzed and an experimental prototype of the flyback converter was constructed. The power spectral densities of the MOSFET current and the conducted EMI test results were presented under different periodic modulating signals. The experimental results demonstrate that both modulating signals can reduce the peak level of the switching harmonics effectively and the spread-spectrum result of the triangular modulating signal is better than that of the sinusoidal modulating signal.更多还原