Time–Frequency and Wavelet Transforms of EMI Dynamic Spectrum in Chaotic Converter

In this paper, a system description of the spectrum of different pulsewidth modulation (PWM) schemes based on time-frequency and wavelet transforms is developed for electromagnetic interference (EMI) suppression in a converter. The wavelet reconstructions of different PWM schemes are obtained exactly. The wavelet coefficients of periodic PWM and of constant PWM have the property of being analogous. The wavelet coefficients of chaotic PWM lack resemblance. The peak of wavelet power spectrum of chaotic PWM fell off sharply at frequency domain and energy transfer to the low-frequency belt. Based on time, frequency transforms, Renyi information, marginal characteristics, and time torque of different PWM schemes are obtained. At last, conduct EMI of an adapter was tested in the case of constant PWM, periodic PWM, and chaotic PWM, respectively, and experimental results testify the theoretical analysis.