Design and analysis of a switched-capacitor-based step-up DC/DC converter with continuous input current

Abstract

This paper presents the use of the current control scheme in switched-capacitor (SC)-based step-up dc/dc converter. It not only includes all positive characteristics of previous SC converters, including small size, light weight, high power density, and the amenability to IC hybridization, but also has the prominent features of continuous input current waveform and better regulation capability than the traditional SC converters. The problem of conducted electromagnetic interference with the supply network, which generally exists in previous SC converters, is highly suppressed. The concept of energy transfer is achieved by using dual SC step-up converter cells operating in antiphase. Each cell is switching between two topologies for the same duration. The dc voltage conversion ratio is controlled by the current control scheme in order to adjust the charging profile of the capacitors. A generalized n-stage converter is presented and is analyzed by a simplified third-order state-space equation set. The static and dynamic behaviors and the design constraints of the converter are derived. A prototype of the 30 W 5 V/12 V two-stage converter has been built, giving an overall efficiency of 78% with power density of 15 W/in/sup 3/. Its stability of operation is also presented.