Practical application of valley current mode control in a flyback converter with a large duty cycle

Author

Chu, Grace M. L. ; Lu, D.D.C. ; Agelidis, Vassilios Georgios

Author_Institution

Sch. of Electr. & Inf. Eng., Univ. of Sydney, Sydney, NSW, Australia

Volume

5

Issue

5

fYear

2012

fDate

5/1/2012 12:00:00 AM

Firstpage

552

Lastpage

560

Abstract

This study proposes the application of valley current mode (VCM) control in a flyback dc-dc converter with a large duty cycle. The use of VCM control eliminates the need of slope compensation in operation under a duty cycle greater than 50-. For operation with duty cycle near the boundary value (50-), a relatively small compensation ramp is required comparing with that of the conventional peak current mode (PCM) control. Moreover, the noise sensitivity issue of PCM control is also addressed by the change of the current sensing position in VCM and hence the immunity against the current spike. The VCM-controlled flyback converter achieves consistent steady-state and transient-response performances as its PCM-controlled counterpart. Stability analyses of inner current loop and overall closed-loop system are presented. Experiments are also conducted to evaluate the effectiveness of VCM control in controlling the flyback dc-dc converter.

Keywords

DC-DC power convertors; closed loop systems; compensation; electric current control; power system stability; transient response; PCM control; VCM control; closed loop system; compensation ramp; duty cycle; flyback DC-DC converter; noise sensitivity; peak current mode; stability analyses; steady-state performance; transient response performance; valley current mode;

fLanguage

English

Journal_Title

Power Electronics, IET

Publisher

iet

ISSN

1755-4535

Type

jour

DOI

10.1049/iet-pel.2011.0225

Filename

6226917