World Journal of Engineering Research and Technology

Yefim Berkovich* and Sagi Moshe

ABSTRACT

The present paper is a study of dynamic modes in DC-DC converters on the basis of energy principles. As is known, the dynamic modes in converters are usually analyzed by forming differential equations systems according to Kirchhoff?s laws ? also using commutation functions ? and subsequently solving them. This leads to non-linear equations of high orders, solved by the averaging method and that by small signal analysis. The analysis turns out to be work consuming and its results are cumbersome and non-transparent, so in practice they can be only applied to the simplest converters. At the same time, with the progress in power electronics the converters? designs are becoming considerably more complicated, making it relevant to seek others, more efficient methods of study. In the present paper the analysis of converter dynamics is based on an approach, which long ago has become classical in mechanics and other fields, yet is still rarely used in electrical engineering. It is based on the use of a function containing the values of the magnetic and electrical energy in a circuit, that is, the function called the Lagrangian which makes it possible to rather easily obtain linearized equations for the averaged voltages and currents values, as well as corresponding linear circuits, the dynamic processes in which are identical with those going on in original converters. In order to illustrate the opportunities and efficiency of the approach, we have made an analysis of the dynamics of all the base converters: the buck-, boost- and buck-boost converters, as well as the Cuk, Sepik and Zeta converters. We also have analyzed a number of converters with more complex structures having an increased number of reactive elements, which more clearly exemplify the advantages of the present approach. All our theoretical results have been confirmed by computer experiments and, in addition, many of the converters under consideration were realized as laboratory models and tested experimentally. The results of the experiments completely confirm our theoretical conclusions.

[Full Text Article] [Download Certificate]