| Chaos is one kind of internal quasi-random movement, which appears in deterministicsystems. It has been paid great attention as a property of nonlinear system in recent20years.A switched-mode DC/DC converter is a typical high non-linear control system, which cangenerate chaotic phenomenon under certain parameters to unstable operation status of thesystem. Thus, with the increasing demand of control performance of DC/DC converter, it’s ofgreat importance in reality to analyze the phenomenon of unstable action and subharmonic ofDC/DC converter from nonlinear theory and chaos theory, and make a much better DC/DCconverter performance.At first, the article introduces briefly the research status and the development of chaosdynamics, discusses the development of nonlinear research in DC/DC converter both in thedomestic and overseas, and presents the content and technical route of this dissertation.Secondly, it introduces in detail the basic conception of differential dynamics theories andchaos dynamics, including classification of Equilibrium point, definition and features of chaos,the route to chaos and common methods to research chaos, etc.Thirdly, combined with the work principle of DC/DC converters, a set of state equationof boost converter will be given. For questions that hardly present systematic high-frequencydynamical behaviors of DC/DC models built by State Space Averaging method, one discreteprecise model of DC/DC converters is suggested by means of Stroboscopic Mapping methodthat completely deducing state-transition matrix in different circuit modes, to discuss andanalyze the chaos and other complicated phenomena in the system, as well as its precision andeffectiveness. Simulations indicate that this model can truly reflect dynamical behaviors inDC/DC converter to acquire fine-structure of evolution from Period doubling Bifurcation(PDB) to chaos. Then, this discrete model is verified by data alignment of another continuousDC/DC model to identify its accuracy and effectiveness.At last, a survey of chaos control is taken to introduce control aids and ideas withcomparison of strength and weakness of different chaotic control method. In order to achievebetter and applicable effects of chaos control in engineering, according to the principle of timedelay feedback control method, a chaotic control has been taken to control chaos in DC/DCconverter. There is no need to generate external periodic small-perturbation signals to changeoperation trajectory from unstable to stable, but to use one part of output signal. The result ofsimulation shows it’s able to change systematic trajectory from chaos to stable periodic statewith a good dynamical performance, which validates the feasibility of chaotic control inDC/DC converter. |
PDF Full Text Request