Size Comparison of Passive Devices of Buck-Boost-Type Converters With LC Filters in CCM: Theory and Method

Abstract

This paper presents a comparison method of passive devices which is applied to buck-boost- type converters with LC filters in order to ascertain the topology for the compact design of such devices in continuous conduction mode (CCM). Design engineers can use the proposed method of size comparison to achieve an efficient and compact buck-boost converter, since volume of the passive devices generally defines converter size. Furthermore, this paper confirms that there is no an unique converter for any specifications instead of that there is a certain topology for a given specifications. This work considers the following buck-boost-type converters: the classical, the interleaved and the three-state switching cell topology. The three-state switching cell is included to show its greater capability to reduce the filter sizes, especially for design with duty cycles of around 1/2. This paper shows also that the filter arrangement is an option to reduce the volume of passive devices and, additionally to provide non-dissipative clamping of the switching devices. In this study idealized mathematical analysis was performed to compare the buck-boost-type converters.