Contents 1. Introduction
The current mode controlled dc/dc boost converter, being one of the most commonly used switch converters in communication and control systems for its high efficiency, is prone to sub-harmonic behavior and chaos. The occurrence of the nonlinear phenomena in the converter has long been a universal experience of practicing engineers [1]. Since the converter has wide industrial application, it becomes necessary to characterize and identify sub harmonics and chaotic signals occurring in the system in order to design stable and reliable dc/dc converters. The first detailed analysis of chaos in power electronics was carried out in reference [2]. Wood, et. al., [3]–[4] have described chaos in the controlled switch mode dc/dc converters. Several other techniques were developed in references [5]–[6] dealing with prediction and experimental confirmation of chaos in dc/dc converters under various control schemes. Most of the conducted research relating to chaotic signals in converter circuits concentrated on the identification of bifurcation path with variations of different parameters in the time-domain trajectory plane. However, a detailed investigation of chaotic signals having different periodicities of the current mode controlled dc/dc boost converter in both time and frequency domains has not been carried out to date. In the last ten years, the wavelet transform has been introduced as a new approach in digital signal processing analysis. The wavelet theory states that a signal can be represented by superposition of some special signals called wavelets. Wavelets are waveforms of limited duration, with zero average value. Apart from the Fourier transform (FT), where a signal is represented by superposition of only one fundamental function (sine or cosine), the WT has an unlimited number of fundamental functions [7]. The WT is somewhat similar to finite response filters, and as such it does not transform the signal into discrete harmonics. However, it transforms signal into frequency bandwidths, which cover all significant harmonics.
