Achieving monotonic variation of spectral composition in DC-DC converters using pulse skipping modulation

Abstract

This paper presents a new type of pulse skipping modulation (PSM) in a dc-dc converter, which is controlled by a voltage mode scheme. The duty ratio of the pulses, instead of being constant as in the conventional PSM, is controlled using a voltage mode control scheme along with a feed-forward path of the input voltage and an adjustable voltage. In the conventional PSM, spectral composition varies nonmonotonically which results in problems due to electromagnetic interference (EMI). We show, both analytically and experimentally, that the proposed scheme results in monotonic spectral behavior for a wide range of input voltage and load resistance. Hence one can obtain the small signal model of the system. Because of the synchronism with the external clock, it facilitates the design of an input filter for reduction of EMI.