Bifurcation Characteristics Of The Converter Under Parasitic Parameters

With the development of science and technology, the traditional linear analysis method cannot effectively solve the problem of nonlinear, nonlinear dynamics emerged, mainly includes three aspects:bifurcation, chaos and soliton. Using the nonlinear circuit model is a good way to solve the problem of power electronic technology, the stability of the whole circuit analysis and the analysis of chaotic phenomena are of great help, by choosing appropriate parameters can effectively avoid the state of chaos, produce positive effects on circuit performance optimization.In recent years, with the widely application of the switch power converter, the switching frequency of the exponential rise, more and more strict with the power loss of switch power supply, the existence of the internal circuit parasitic parameters become one of the main loss of switch power converter, these parasitic parameters can make the efficiency of the whole circuit is low, the reactive power increasing, the absorption of output power loss and damage to the transducer signal at the input, so as to affect the service life of the input power supply. In order to design the parameters of the switch power converter better, we need to study these components parasitic parameters on the stability of the circuit.This thesis first introduces the definition, characteristics, importance of nonlinear dynamics, specific examples, and is closely related to the DC-DC converter type of bifurcation, discussed the specific methods of DC-DC converter modeling and other basic knowledge; And then analyzes the detailed work process of the Buck converter, using state space average method of converter modeling;Finally in the Buck converter, for example, there are five:its main parasitic parameters on the dc source internal resistance, switch tube on resistance, diode is the guide of parasitic resistance on the voltage, capacitance, inductance on the parasitic resistance. Fixed by four parameters constant, with the rest of the a parameter as a variable, into the equation of state of the circuit, observe its bifurcation points and bifurcation diagram ideally bifurcation point, what is concluded that the stability of the circuit interval, which concluded that the parameters to affect the overall circuit. Discrete iterative mapping function by constructing the Buck converter, USES the stroboscopic map, the method of computing jacobian matrix of the system, and get the balance place characteristic root, at the same time build Simulink simulation model section switch to the Buck converter, get change with the input voltage E characteristics of root locus, to judge the stability of the system, if the unit circle term system stability; If outside the unit circle, then the system is unstable. Theoretical analysis and simulation results are consistent, suggesting that the parasitic parameters of the Buck converter indeed caused a certain influence to the stability of the system, namely the converter parameters can make the system unstable bifurcation phenomenon.The conclusion of this thesis for the analysis and design of the actual circuit has a great significance to subsequent workers can effectively avoid because of the influence of the parameters of system bifurcation, the appropriate choice of parameter values can make the system stable range becomes larger, the whole circuit loss is smaller and less reactive power.