Application of the Wavelet Packet Transform for the Identification of Chaotic Signals in the Current-Programmed DC/DC Boost Converters

The wavelet packet transform (WPT), a digital realization of the wavelet transform (WT), has been used in this work for identifying and characterizing sub-harmonic and chaotic signals in a current-mode-controlled boost converter. The operation of the boost converter under current-programmed control is explained, and some computer-generated waveforms are presented in order to illustrate the various possible operating regimes of the current-programmed dc/dc converters. Samples of the state variables of different periodic and chaotic operating conditions of the converter are decomposed up to a certain level of resolution of the wavelet packet tree using a selected mother wavelet in order to characterize different sub-harmonic and chaotic signals occurred in the converter. The wavelet-transformed coefficients of the sampled state variables of different frequency sub bands of the wavelet packet tree are able to differentiate effectively between different periodic and chaotic operating conditions of the converter.