Wavelet analysis of the effectiveness of conducted EMI reduction in power converters

It has been demonstrated that modulating the switching frequency of a power converter is a worthy way to reduce EMI due to switching process. Since modulations following periodic patterns are time dependent processes, wavelets are well suited to analyze the performance of such techniques. Wavelet analysis shows the frequency content of the switching waveform as a function of time that cannot be seen using conventional Fourier analysis. In this paper, wavelets are used to compare three periodic modulation patterns by means of figures of merit derived from time-dependent energy density distribution in frequency, represented by the scalogram. Similar indexes of merit, involving coscalograms, are proposed to be used in the future work.