Quantitative Analysis And Control Of Dynamics In High Order Systems Of DC-DC Converters

DC-DC converter is the basic circuit unit of many other types of power electronicconverters, the stability and the reliability of its operational status has important referentialsignificance to analyze the working performance of the power electronic converters. Thenonlinear dynamics phenomena of DC-DC converter, such as period-doubling bifurcations,border collision bifurcation, coexisting attractors and chaos, have been verified byexperimental analysisis. However, the current researches have focused on low order systems,such as Buck, Boost, and Flyback converters. And there is little studies for high order systems,including uk, SEPIC and full-bridge DC-DC converters, which have more than four statevariables. Especially, quantitative analysis and control of bifurcation and chaos phenomenafor DC-DC coverters of high order systems are in the beginning state. Therefore, quantitativeanalysis and control of nonlinear dynamical behavior in high order systems of DC-DCswitching converters will help ones to further broaden the understanding of power electronicstechnology and its applications.The study in this dissertation can be summarized as follows:(1) The complex instabilities and coexistion of different bifurcation phenomena nearcodimension-2bifurcation point are analyzed in a single inner current loop controlled ukconverter with an inductive impedance load. the coexistion phenomena of fast-and slow-scalebifurcation behavior is analyzed theoretically in a uk converter with a constant currentsource load, and its characteristics of nonlinear dynamics is revealed.(2) The switching time map and modal symbolic sequence method is utilized to reveal thecomplex dynamic behavior in high order system of DC-DC converter, and the quantitativeanalysis of its complex nonlinear states is actualized in terms of joint entropy. According tothe characteristics of changing topologies of SPEIC converter, moreover, the stability indexconcept is put forward to quantify the stabilities and nonlinear dynamic character of its highorder systems based on Lemper-Ziv complexity.(3) The nonlinear model of DC-DC full-bridge resonace converter is estabilished withloosely coupled transformer and voltage mode control, and the onlinear behavior of thesystem, e.g. Hopf bifurcation, is analyzed when it work in resonace state. There has theoryand engineering significance to design the more stable and reliable resonance wireless powertransmission system based on DC-DC full-bridge resonance converter. (4) The nonlinear stabilizing method of LLC resonance full-bridge DC-DC converter isput forward. The state variables of the converter is sampled and fed back in this method,which effectively stabilizes the bad behavior of nonlinear dynamics. Moreover, the EMI ofthis converter is reduced by the spread spectrum technology with chaotic n-croll wave.In summary, four high order DC-DC converters, including uk converter, SPEICconverter, DC-DC full-bridge resonance converter with loosed coupled transformer and LLCresonance full-bridge DC-DC converter, is took as the studing object in this dissertation. Thenonlinear dynamic method is utilized to quantify and analyze their complex nonlineardynamics behavior. Additionally, the novel stabilizing method of nonlinear behavior and thetechnology of suppressing EMI are put forward. This dissertation promotes the study ofdynamic characteristic in high order DC-DC converter.