Modeling, Control And Application Of PWM DC/DC Converter Based On Chaotic Dynamics

Power electronic circuits can show rich nonlinear phenomena, such as bifurcations, chaos and etc. Therefore chaotic dynamics is needed to analyze these phenomena. Modeling power electronic circuits with chaotic dynamics can help us to learn more about dynamic behaviors of power electronic circuits, which is beneficial to engineering design. On the other hand, power circuits will supply instances for the study of nonlinear science, which, as a result, can also contribute to the development of nonlinear science. For example, a C-bifurcation phenomenon is observed in this dissertation, while at present, there is no such C-bifurcation theory to describe and predict the C-bifurcation phenomenon. In this dissertation the nonlinear phenomena in PWM DC/DC converter are studied from three aspects: a complete PWM DC/DC modeling method with chaotic dynamics was first generated; and then chaotic controlling technology in PWM DC/DC converter was studied based on the modeling method; at last, the research on engineering application of chaotic phenomenon in DC/DC converter is illustrated. In this dissertation Genetic Arithmetic is used to find periodic fixed point of DC/DC converter system. While a new crossover operator is submitted to accelerate the convergence speed of GA. Three kinds of discrete models of PWM DC/DC converter are deduced from Sample-Data method. Then a complete chaotic dynamics modeling method is proposed based on Float Genetic Arithmetic and Sample-Data method. Nonlinear phenomena in a Buck converter and a Zeta converter are analyzed with the modeling method.OGY method was used to control chaos in DC/DC converter. But the periodic orbit of the system must be found, before OGY method can work. Sometimes it is difficult to predict and calculate the periodic orbit, so the chaotic control technology based on Washout filter is used to control chaotic phenomena of DC/DC converter. And the simulation results show the validity of the method.Since a DC/DC converter running in chaotic state can improve its EMC, we can make engineering application. But if we use chaotic phenomenon directly, three disadvantages exist: (1) the applied range was limited by dynamic character of the DC/DC converter system; (2) high current fluctuation is found, and it is hard to be controlled; (3) high output voltage fluctuation. To overcome the first shortage chaos control technology is used to control a DC/DC converter from periodic state to chaotic region. And then a new scheme, named chaotic sequence parameter perturbation method, was proposed. Computer Simulation shows that the new scheme can avoid the three disadvantages mentioned above.