| The core of switching power supply is switching converters. Therefore, the studies of switching converter topology and modeling of switching converters have been a research hotspot issues and key issues. In this paper, on the basis of equivalent small parameter method, modeling analysis and simulation on switching converter were studied.The state-space averaging method is the most widely used method to model and analysis switching converter. It has clear physical meaning and simple modeling method. But the converter is a typical nonlinear system, due to the state space method uses the "average" approach and the restriction on application, it exist some shortcoming, such as it can not be applied to low-frequency converters, steady-state analysis is not accurate and it does not reflect the ripple characteristics. The equivalent small parameter method can fill this gap. This method not only can be used in DC-DC converters, but also can be used for modeling analysis of quasi-resonant converterThis paper describes the modeling theories of the equivalent small parameter method, take BUCK converter as example to illustrate the general steps of modeling. The simulation results comparing of it and state space method as well as physical simulation proved that the small parameter method used on converter modeling is the validity and accuracy. It also illustrated the equivalent small parameter method has advantages compared to state-space method. A prominent advantage of small parameter method is analyze the ripple. On the view of numerical analysis, with the traditional four-order Runge-Kutta method, verify the feasibility of which the equivalent small-parameter method analysis to solve ripple.Finally, the equivalent small parameter method was extended to the closed-loop switching converter control system. We can sum up the closed-loop system modeling methods and its benefits. Compared to other modeling methods, the equivalent small parameter method can be simple, intuitive, and accurately to find the DC solution and the second harmonic component, expressed the non-linear characteristics of the converter maximum. At the end of the article, the author made some prospect on the future research work, and presented some problems to resolve. |
