Application of the Wavelet Transform to the Analysis of Conducted EMI in SMPSs

The Continuous Wavelet Transform (CWT) is used to extract information about the time evolution of the conducted noise generated by a Switch Mode Power Supply (SMPS). The CWT is compared to the Discrete Fourier Transform (DFT) in an analysis of the noise signal measured by a pre-compliance Electromagnetic Interference (EMI) receiver. The results show how the CWT makes it possible to identify noise-generating events by correlating the converter time operation to the measured spectrum. This may be the base for a design tool to be used as a guide in the mitigation of the generated EMI.