Current-Loop Control In Switching Converters Part 1: Historical Overview

Focus:

Peak or valley current control of switching converters is well established in engineering practice. Yet the irony of current-loop control is that, after decades, its theory is still undergoing refinement. This is the result, in part, of the complexity of the seemingly simple current-loop controller circuit. Its typical circuit diagram has few parts, yet the current-feedback loop is nonlinear and switched, having discrete-time behavior. This series of articles reviews the history of current-loop control theory (i.e how to accurately model current-mode control.) This article attempts to clarify established concepts, identify problems with the existing theories or models of the current-mode control, and then offer what might be the first truly unified model of current control. Here in part 1, the author reviews the previous work done in modeling current-mode control using waveform-based approaches. These include work by Erickson and Macsimovi?; Ridley; Tymerski and Li; Tan and Middlebrook; Hong, Choi and Ahn; and Holloway and Eirea. The author also discusses Sheehan's circuit-based modeling. Following this historical review, the author discusses subtleties in the waveform based models and how they are relevant to the development of the "ultimate waveform-based model" of current-mode control, which the author aims to develop in this series.

What you’ll learn:

• How to understand historical development of models for current-mode control in switching power converters
• How to understand differences between and limitations of various models of current-mode control in switching power converters

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Author & Publication:

Dennis Feucht, Innovatia Laboratories, Cayo, Belize, How2Power Today, Sep 27 2011

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