Bifurcation Analysis Of The Converter Based On Nonlinear Circuit Theory

Since the1960s, nonlinear science, as well as various non-linear phenomenon has aroused people’s interest. With the rapid upgrading of computer hardware performance and the development of scientific theories,which laid a good foundation for the rapid development of nonlinear science. The nonlinear science study the commonality between a variety of nonlinear phenomena. Development of nonlinear science being called "the third great revolution of the20th century natural science", which covered almost all aspects of the natural and social sciences,including:biology, meteorology, economics, electronics, fluid mechanics, and so on. Nonlinear theory of science not only have great significance to science, but also have a more broad application prospects. Nonlinear scientific research has involved the chance and necessity, the identification theory and stochastic theory, ordered and unordered, qualitative and quantitative changes, refresh the common concepts for those and change the understanding of the traditional world.The development of nonlinear scientific expand people’s viewpoint of recognizing the world. It provides a powerful tool to increase awareness and improvement of the natural and human world.In the process of nonlinear science development, study of chaotic phenomena accounts for a significant part. Sine1975,the word "Chaos" appear in the scientific literature by given a whole new meaning. Today, the chaos phenomena has been widely accepted, and for the development of chaos theory is bound to further deepen the understanding of the natural and social phenomena. The development of Chaos also need to face the problem of the application. The one hand, the successful application of chaos theory will help to encourage people to invest more energy, on the other hand, the new challenges faced by the chaotic application will also promote further study of chaos theory.Due to the initial value sensitivity of chaotic motion, as well as long-term behavior of the unpredictability of features,chaos control become the key of chaos application. Since the late1980s, a lot of paper about chaos control theory have published and many chaos control and chaos synchronization ideas have been proposed, and chaos control experiments completed, chaos control and chaos synchronization became the hot areas of chaos theory. The consensus about chaos control is that impacting the chaotic system effectively, let the system to step out of the chaotic state and achieve the actual needs of the state.Switching converter is a common power electronic circuit, widely used in power transmission systems. Switching converter as a class of strongly nonlinear systems, in the course of their operation can produce a wealth of nonlinear phenomena, such as: bifurcation, coexistence attractor, chaos and so on. This thesis takes switching converters as examples to analyze the work process and principles, and establish the corresponding dynamic model, using Matlab-Simulink software to build simulation models, simulation its work progress thus achieve accurate simulation results.In this thesis we describe the nonlinear characteristics in a general current control mode Buck converter during its operation and the nonlinear characteristics in the Buck converter whose constant current source instead of rectifier source.When the system parameters change make qualitative change of dynamic system, we call it " bifurcation ". Power electronics converter is usually designed to work under certain conditions, such as a specific output voltage ripple and so on. However, when the input voltage or a load resistance changes, will make fundamental changes in the operation of the system. Therefore, the study of bifurcation in such systems is very important. Through the bifurcation diagram of the system to reaserch is quite convenient. Because it can directly show as the system parameters incremental change, how the system state is changed. System period and the operational status of system parameters in which to enter the chaotic state shown in bifurcation diagram. But the bifurcation diagram we usually see is one-dimensional, that is caused by one of the system parameters changes. In this thesis, based on a one-dimensional bifurcation diagram,we increase the number of bifurcation parameter to two or even three, and we will drawing two-dimensional bifurcation diagram in the two system parameters and drawing three-dimensional bifurcation diagram in the three system parameters change.