Spectral Analysis of DC-DC Buck Converter with Chaotic Dynamics

Chaos, a specific type of nonlinearity is commonly found in nonlinear deterministic systems. The DC-DC converters have been reported as exhibiting a wide range of bifurcation and chaotic behavior under certain conditions. Thus the design objective of Buck converter must include the stable operation of Buck converter at switching frequency and prevention of any bifurcation within the intended operating range. This paper reviews our studies on the observation of nonlinear, ubiquitous chaos in designed DC-DC buck converter whose output voltage is controlled by PWM switching, operating in continuous mode. Subharmonics, ultraharmonics and chaos of buck converter have been investigated and different route to chaos were derived by simulation and confirmed by numerical analysis. The nonperiodic appearance of the converter´s response may suggest chaos. But it does not by itself prove that a response is chaotic. Quantitative measures like a distributed frequency spectrum of the system response is required to prove chaos Hence Time frequency analysis is used for investigating the frequency pattern of chaos generated in Buck converter circuit. Power spectrumn and spectrograms are used as principle tools for the qualitative evaluation of behavior of nonlinearity in Buck converter and the results confirm the advantages of this advanced method for better explanation and prediction of chaos.