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Study On Discrete Time Mapping Modeling And Nonlinear Behaviors Analysis For Soft Switched Circuit

Posted on:2007-04-19Degree:DoctorType:Dissertation
Country:ChinaCandidate:X DaiFull Text:PDF
GTID:1102360212468464Subject:Control theory and control engineering
Abstract/Summary:PDF Full Text Request
In power electronics circuits, there are mainly two switching modes, named hard switching mode and soft switching mode. The hard switching mode realizes energy transformation with aid of abrupt change of power flow. And the soft switching mode realizes flexible energy transformation with aid of natural zero crossing points of power flow. For switching components switching at the zero voltage or zero current points, the switching loss will become zero in theory, and switching loss and switching noise can be minimized. So, soft switching circuits get widely used in the past decade and become the main stream and research interest of power electronics converter.However, in the soft switching circuits running, many strange phenomena are observed, such as abrupt state change, unknown electro-magnetic noise, frequency unstable and unwanted operating state. Recent research show: some strange phenomena are rooted in the inherent nonlinear characteristics such as bifurcation and chaos in soft switching circuits. These strange phenomena will result in that system running state can't be predicted and controlled. Aimed at nonlinear modeling and dynamic behaviors analysis, the main works of this paper are as follows:1. The paper analyzes recent soft switching circuits and relative operating mode and concludes the system characteristics of soft switching circuits, namely, high dimension, autonomous piecewise smooth and vibration. These characteristics differ soft switching system from hard switching system , and result in different dynamics behaviors in operation.2. For the autonomous piecewise smooth characteristic of soft switching system, the classical discrete mapping method can't be directly used. This paper proposes a precise discrete time mapping modeling method. This method is a numerical one. Furthermore, in order to improve the solution accuracy on the switching boundary, this paper put forwards a correct method for this discrete mapping model based on Girlerkin method. At last, this paper takes Multi-Resonant soft switching circuits as an example of this modeling method. The simulation results get verified by accurate analytical model.3. The precise discrete time mapping modeling method is a numerical method. There exist some shortcomings such as implicit physical meaning, large computing work. In this paper, a generalized discrete time mapping modeling method is proposed.
Keywords/Search Tags:Soft switching circuit, Discrete time mapping modeling, Frequency jump phenomena, Discontinuous bifurcation
PDF Full Text Request
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