| Chaos is a motion state that is determined but unpredictable in system. This kind of ’unpredictable’ phenomenon is mainly produced in non-linear systems. By researching DC-DC converter in switching power supply, we found discovered that corresponding to the circuit configuration is also different due to the state of the switch tube, a large number of bifurcation and chaos phenomenon are produced in the changing process, such as system collapse caused by sudden disorder, output instability in systems caused by the intermittent oscillation and the emergence of much of electromagnetic interference. Therefore, by research of chaos phenomena in DC-DC converters, we can learn more about this nonlinear behavior, in this way, we can choose reasonable parameters in the design of switching power supply circuit, in order to avoid chaos phenomenon, so that the output can be more stable.This thesis describes the knowledge of chaos theory, a few basic features of chaos phenomenon, technical indications used to determine a chaos system, as well as several typical circuits that lead to chaos in DC-DC converters. Then by a thorough study of the chaos dynamics modeling methods in DC-DC converters, and ultimately discrete-time nonlinear iteration mapping of the system state variables is selected to analyze the Buck-Boost, Flyback converter Chaos and bifurcations, Buck-Boost Converter flyback converter as the object of study, by a brief analysis of their basic working principles, their discrete-time iterative nonlinear mapping model is established, the simulation is also did in Matlab, input voltage and inductor power are selected as sensitive parameter of the system, we obtain the bifurcation diagram of a converter when they change, in this way, we can research the relationship between chaos phenomena as well as bifurcation phenomena and sensitive parameters in systems. Finally system simulation circuit of Buck-Boost Converter is established in Saber, Input voltage as a sensitive parameter of the system, to observe the time-domain waveform of the voltage across the capacitor and inductor current changes in each cycle, and further verify the correctness of discrete mathematical model and Chaos as well as bifurcation phenomenon in converters.An irreplaceable position in the power market, application flyback converters in the design of the power, has a great advantage in the output power of less than150W, we designed a small flyback switching power supply which the output is18W, based on earlier research, the related component selection and parameter calculation are also given, a sample machine was made to test related functions. Experimental results show that:the switching power supply output is relatively stable, and can meet the design requirements basically. |
PDF Full Text Request