| DC-DC switching converter is one of the core contents of the switching power supply,its invention started in the 1950s,but at the beginning of the invention,it was only used in the fields of military and aviation due to the high cost.By the 1970s,with the development of power devices and their widespread use,more and more switching converters were used in power supplies.The main advantages of the switching converter are:high efficiency,light weight,small size,the cost is lower than the linear converter after the power is greater than a certain value,suitable for a wide range of supply voltage,suitable for a wide range of supply frequency,but at the same time,switching converters There are some shortcomings,such as:large ripple,RF and magnetic field interference,no special measures can not be empty,the circuit is more complicated than the linear converter and the failure rate higher.The DC-DC switching converter,as a kind of strong nonlinear system,exhibits some nonlinear dynamic behavior during the operation.The conventional control algorithm can not achieve satisfactory results for the study of these behaviors.By the 1980s,people combined power electronics with nonlinear dynamics,which provided a new way for people to study the complex dynamics in DC-DC switching converters.National experts and scholars make use of the theory of bifurcation and chaos in nonlinear dynamics to explain the nonlinear dynamic behavior of DC-DC switching converter more reasonably.It is found in the study that it will produce double Periodic bifurcation,Hopf bifurcation and boundary collision bifurcation.At the same time,the mechanism of bifurcation is also analyzed theoretically.The results show that these bifurcations cause the system to produce chaos.These findings have effectively solved some of the problems that have long plagued electronic engineers.This thesis is based on the research of predecessors.Based on current-mode controlled Boost converter circuit and parallel Boost circuit,the bifurcation and chaos behavior of them are discussed.Finally,use a bifurcation control methods,the stability of the system has been improved.The main contents of this thesis include the following points:(1)Review the research progress of nonlinear dynamic behavior in DC-DC switching converter,and explain the purpose and significance of the research direction,and propose the research direction and content of this thesis.(2)Introducing the theoretical knowledge of nonlinear dynamics,starting from the three aspects of linearization and stability,bifurcation theory and chaos theory respectively,which provide the theoretical basis for the later development.(3)Taking the current-mode controlled Boost converter as the research object,the discrete iterative mapping model and the exact state equation model are established respectively.According to the state equation,the simulation model is established in simulink in Matlab,and the bifurcation diagram is obtained when different parameters change.At the same time,four different values of one of the parameters were selected and their waveforms,phase diagrams and Poincare sections were drawn,which proves to be consistent with the results indicated by the bifurcation diagram.(4)The parallel Boost converter is taken as the research object,its working principle is introduced,its state equation is deduced,and its simulation model is established.At the same time,the bifurcation diagram of the Boost converter with different parameters is deduced to reveal its dynamic behavior.(5)Based on the previous research,in order to control the bifurcation behavior of parallel Boost converter and use delay feedback control method,the stability of the system is improved. |
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