Research Of Chaos In DC-DC Converters

The appearance of strange or irregular phenomenon , including intangible electromagnetism noise,control system's instability and system state's abrupt collapse is a representation of chaotic operation of power converters. Chaos is the exterior representation of nonlinear character of DC-DC converters. Now the chaos research has been a most popular topic in power electronics research field. But, because of the nonlinear and complexity, the study of chaos is still in a elementary phase. Based on Boost/Buck converters, this paper has studied and simulated deeply in the aspect of operation procession, discrete-time modeling, bifurcation discussion of converters.The main work of this paper is shown in details as follows:(1) Briefly introduce the former study of chaos and the common method of chaos modeling. These content has set a foundation of time-discrete modeling of the soft-switching converters and the introduction of transform-domain analysis method.(2) Based on module theory, the operation state analysis of voltage-feed ZCS Boost converter has been simplified and the time-discrete mathematic modeling of DCM mode has been setup.(3) The stability operation parameter range has been decided according to the stability criterion, and the analysis of influent of resonance inductance and capacitance to converter's chaos character is carried out.(4) The transform-domain analysis method is firstly introduced into the nonlinear analysis of DC-DC converters. The mathematic model of current-control Boost/Buck converters operating under CCM/DCM mode is proposed, and the time-discrete system function is established based on Z-transformation.(5) The stability parameter range is decided according to the time-discrete system stability criterion under Z-transformation. The change procession of DC-DC converters from instability to chaos is validated according to Pspice simulation. And the decisive influence of operation mode and feedback control method is discussed.