Based on the analysis of constant frequency, periodical frequency-spreading scheme and chaotic frequency-spreading scheme, the article has discussed the mechanics and the characters of the chaotic PWM suppressing EMI in the converter. Experiments have been made on an AC-DC forward converter. The experiment results show that the EMI spectrum is decided completely by the PWM spectrum, and the chaotic frequency-spreading has an obvious impact on EMI suppressing, compared with the other schemes. The frequency character of the ripple has been changed but the peak value and the shape of the ripple have kept almost the same as before, and after the frequency is spread chaotically, the converter system works stable. The article has made up the lack of theory analysis and experiment analysis of chaotic PWM suppressing EMI.

No abstract