Small Signal Modeling of a High Bandwidth Voltage Regulator Using Coupled Inductors

Author

Xu, Ming ; Zhou, Jinghai ; Yao, Kaiwei ; Lee, Fred C.

Author_Institution

Dept. of Electr. & Comput. Eng., Virginia Polytech. Inst. & State Univ.

Volume

22

Issue

2

fYear

2007

fDate

3/1/2007 12:00:00 AM

Firstpage

399

Lastpage

406

Abstract

Today´s voltage regulator (VR) for the microprocessor requires a current loop to achieve adaptive voltage positioning and phase current sharing. A fundamental limitation, current loop sample hold effect, limits the control bandwidth to be pushed beyond 1/6 of the switching frequency. This paper reveals the limitation of the control bandwidth of a two-phase buck converter using peak current control scheme. The limitation can be overcome by coupling the two output inductors. A new small signal model is proposed to study the sample hold effect in coupled-inductor implementations. The relationship between the coupling coefficient and the sample hold effect is then discussed. Based on these understandings, a strongly coupled two-phase buck converter has double the bandwidth of the noncoupled VR; and this is experimentally verified

Keywords

electric current control; inductors; position control; power convertors; voltage regulators; adaptive voltage positioning; coupled inductors; high bandwidth voltage regulator; peak current control scheme; phase current sharing; sample hold effect; small signal model; switching frequency; two-phase buck converter; Bandwidth; Buck converters; Capacitors; Current control; Inductors; Microprocessors; Regulators; Switching frequency; Virtual reality; Voltage; Coupled inductors; high bandwidth; small signal modeling;

fLanguage

English

Journal_Title

Power Electronics, IEEE Transactions on

Publisher

ieee

ISSN

0885-8993

Type

jour

DOI

10.1109/TPEL.2006.889905

Filename

4118337