1971 - [YU71A]

Yuan Yu and John Biess of TRW give first explanation and analysis of the problem in current power electronics literature. They propose a two stage input filter with controlled damping that remains a popular solution. [KP]

1971 - [BIES71A]

John Biess and Yuan Yu of TRW provide a detailed analysis of a two-section input filter with controlled damping, a widely used solution to the input filter interaction problem.

1973 - [SOKA73A]

Nathan Sokal of Design Automation, Inc. discusses the system aspects of the input filter interaction problem, makes efficiency an explicit variable of the analysis, and suggests remedies.

1975 - [MIDD75A]

R. David Middlebrook of Caltech, in an application of a circuit-averaging analysis technique, shows that the presence of an input filter can cause a severe disturbance, even a null, in the control duty ratio describing function, with consequence potential performance difficulties.

1976 - [MIDD76C]

R. David Middlebrook of Caltech provides the definitive analysis of the problem for voltage-mode control using modeling techniques newly developed at Caltech. Shows shortcomings in earlier analysis in predicting oscillations and shows degradation of other performance parameters under certain conditions. Develops graphical method called the Middlebrook Criterion that is routinely used to test for potential problems. Discusses input damping techniques for single-section low- pass LC filters, two stage input filter with controlled damping, and a shunt damped single-section low pass LC input filter. [KP]

1978 - [MIDD78C]

R. David Middlebrook of Caltech revisits and expands his earlier analysis and provides detailed analysis of the deceptively simple shunt-damped single-section low-pass LC input filter.

1979 - [PHEL79A]

T. K. Phelps and W. S. Tate of Hughes Aircraft provide the characteristics of nine commonly used input filters with damping for use with switching mode power supplies. [KP]

1982 - [KELK82A]

S. S. Kelkar and F. C. Lee of VPI propose, analyze, and measure a feed-forward pole-zero cancellation technique to minimize the effect on the control loop of the input filter. The use of this technique is controversial.

1983 - [MHB241]

Criterion developed by R. D. Middlebrook of Caltech is incorporated into the MIL-HDBK-241B design guide for electromagnetic interference reduction in power supplies and called the Middlebrook Criterion.

1985 - [MIDD85B]

R. D. Middlebrook of Caltech presents the need to damp input and output filters for both small-signal and large-signal reasons in practical designs. An argument against the utility of feed-forward pole-zero cancellation in practical designs.

1989 - [LEWI89A]

L. R. Lewis, B. H. Cho, F. C. Lee, and B. A. Carpenter show how cascaded switching-mode power supplies interact and how to place an EMI filter between them.

1990 - [ERIC90A]

S. Y. Erich and W. M. Polivka develop both analytical and graphical impedance criteria for current-programmed converters similar to those for duty-ratio programmed converters. This criteria is more complex, usually requiring computers to calculate the curves, which look much different than the duty-ratio curves, and are highly dependent on converter type and parameters. They show for a buck converter example that the voltage loop gain and output impedance can essentially be unaffected by an input filter about to cause instability in a buck converter, negating these traditional measures of performance as indicators of system stability for current-programmed buck converters. Also discussed is the "black box" problem of designing a filter with partial knowledge of the circuit and of paralleling multiple converters on one filter. Republished without the "black box" and paralleling discussion in ERIC92A

1990 - [KOHU90A]

C. R. Kohut develops an analytical and graphical admittance criteria for the current-programmed buck converter that supports the findings of Erich and Polivka. Substantially revised in KOHU92A

1991 - [JANG91B]

Y. Jang and R. W. Erickson revisit the Middlebrook criteria for current-programmed converters, show that the origin of the current-programmed converter instability is a feed-forward loop and the original Middlebrook criteria, with the addition of a condition associated with the feed-forward loop, assures stability. The APEC'91 paper was not available for publication but the paper is in printed in a 1992 PELS paper.

1991 -

Cho, B.H., and B. Choi, **Analysis and Design of
Multi-Stage Distributed Power Systems**, INTELEC Conf. Rec. 1991, pp.
220-226. (To be completed. JF)

1993 - [FLOR93A]

Martin Florez-Lizarraga and Arthur F. Witulski develop criteria for operating multiple converters from a dc bus with non zero source impedance. Updated in 1996 paper.

1995 - [CHOI95A]

Byungcho Choi and Bo H. Cho expand the Lewis et.al. 1989 cascaded converter work to develop a noniterative design procedure for placing an EMI filter between cascaded converters and illustrate the procedure for a popular one section and two section filter.

1996 - [FLOR96A]

Martin Florez-Lizarraga and Arthur F. Witulski update and republish their 1993 criteria for operating multiple converters from a dc bus with non zero source impedance.