Dissertation > Industrial Technology > Electrotechnical > Transformers, converters and reactors > Converter

Study of Chaos and Its Control in the DC-DC Converters

Author DongZhongWen
Tutor HeLiHong
School Northeastern University
Course Theory and New
Keywords DC-DC converters Poincare section bifurcation chaos chaos control
Type Master's thesis
Year 2009
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DC-DC switching converter is an important part of power electronics, belonging to strong nonlinear time-varying systems. In the course of their traditional research, which rarely involves the study of nonlinear phenomena. However, in the actual design process of the switching converter, sometimes we would find a number of non-normal phenomena, such as that output voltage and magnitude is not fixed; bring about harsh noise and so on, all these phenomena indicates that the existence of chaos. Because chaos is a state as a result of instability, the uncertainty will lead the operation of the system to phenomena like Random, which affect the control performance of converter, even lead to not working, the study of chaos in the switching converter and its control methods which have important guiding significance in the correct designing and debugging switching converter will help us to avoid or eliminate this phenomenon in the design, so that the converter works in a stable cycle.This paper firstly reviews the history of the development on the study of chaos and its control, and the relevant non-linear phenomena in electronic circuits, then research on bifurcation and chaos theory of the converters, and make a lot of in-depth study of the chaos phenomenon in the Buck and Boost circuit, the iterative discrete mapping model and state-space equation on their continuous mode are builded up. Through simulation, their time-domain waveforms and phase trajectory map are got, through programming, their Poincare sections, bifurcation diagram are got respectively, then the mutative process are revealed from stability to bifurcation to chaos in DC-DC converters with the change of parameters, and point out the region of coexisting attractors. In addition, through accurate simulation of the Boost circuit, we detail period-3 window, tangential bifurcation and intermittency chaos.In this paper, we analyze chaos control of DC-DC converters under the chaotic state, using differential current negative feedback control for Buck circuit, we successfully fix the orbits on period-1, period-2, period-4 state; for Boost circuit through adding a nonlinear feedback controller of piecewise quadratic function x|x| forms, the state of Boost can be well fixed at period-8 and period-4. And the controllable range of these two methods are given respectively under certain conditions.

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