开关变换器混沌PWM抑制EMI的机理和实验研究

在分析定频、周期扩频和混沌PWM频谱分布基础上，深入探讨了开关变换器混沌PWM抑制EMI的机理和特点。由此在1台AC-DC反激式变换器上进行了详尽的实验研究。分别进行的定频、周期扩频和混沌PWM实验结果表明，EMI的频谱分布取决于 PWM频谱分布，其中混沌PWM抑制EMI效果最好，虽然开关变换器输出电压的纹波频率随混沌扩频信号改变，但峰峰值基本不变。稳定性和效率测试显示，混沌PWM下开关变换器运行稳定，效率变化不大。该文较好地弥补了现有混沌PWM抑制EMI实验研究的不足。

Experiment and Mechanism Research of Chaotic PWM of Converter in EMI Suppressing

Based on analysis of the spectrum of constant frequency PWM, periodical frequency-spreading PWM and chaotic frequency-spreading PWM, mechanism and characters of the chaotic PWM of converter for EMI suppressing were discussed. Experiments were made on an AC-DC flyback converter. The experimental results show that the PWM spectrum decides the EMI spectrum of converter and the chaotic PWM has the best effect in EMI suppressing. The shape of ripple changes but the peak value of the ripple keeps almost the same as before, the system works stably under chaotic frequency-spreading circumstance.