Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/699
Title: Sustained slow-scale oscillation in higher order current-mode controlled converter
Authors: Wong, Siu-chung
Wu, Xiaoqun
Tse, C. K. Michael
Subjects: Bifurcation
DC-DC converters
Ćuk converter
Current-mode control
Issue Date: May-2008
Publisher: IEEE
Source: IEEE transactions on circuits and systems. II, Express briefs, May 2008, v. 55, no. 5, p. 489-493.
Abstract: DC-DC converters under current-mode control have been known to exhibit slow-scale oscillation as a result of a Hopftype bifurcation as one or more of the parameters of the outer voltage loop are varied. In the absence of the outer voltage loop (i.e., open loop), slow-scale oscillation was generally not observed in simple low-order dc-dc converters, i.e., buck, buck-boost, and boost converters. In this paper, slow-scale bifurcation in a higher order current-mode controlled converter is studied. It has been found experimentally that, even in the absence of a closed outer voltage loop, a current-mode controlled Ćuk converter can exhibit a slow-scale Hopf-type bifurcation. The phenomenon was observed in a commercial low-ripple dc-dc converter which has been designed using the Ćuk converter and the LM2611 controller. Such slow-scale oscillation of the inner current loop can also be observed in full-circuit SPICE simulations. An averaged model has been developed and implemented in SPICE to find the Hopf bifurcation boundaries. With this averaged model, the Hopf bifurcation can be explained conveniently using the traditional loop gain analysis. Specifically, the extra degrees of freedom in higher order dc-dc converters have opened up a new possible mode of instability which has not been found in simple low-order dc-dc converters.
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Type: Journal/Magazine Article
URI: http://hdl.handle.net/10397/699
DOI: 10.1109/TCSII.2007.914438
ISSN: 1549-7747
Appears in Collections:EIE Journal/Magazine Articles

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