Eliminating the Temperature Effect of Piezoelectric Transformer in Backlight Electronic Ballast by Applying the Digital Phase-Locked-Loop Technique

Author

Lin, Chang-Hua ; Lu, Ying ; Chiu, Huang-Jen ; Ou, Chung-Lun

Author_Institution

Dept. of Comput. & Commun. Eng., St. John´´s Univ., Taipei

Volume

54

Issue

2

fYear

2007

fDate

4/1/2007 12:00:00 AM

Firstpage

1024

Lastpage

1031

Abstract

A new controller for eliminating the temperature effect of a piezoelectric transformer (PT) in a backlight electronic ballast is proposed in this paper. First, a class-D backlight inverter is employed to simplify the circuit configuration and to raise system efficiency. Next, to reduce the dimensions of the backlight module for satisfying the thin-shaped design trend and to overcome the drawbacks of a conventional transformer, a PT is incorporated instead. Then, a digital phase-locked-loop (DPLL) controller is embedded into the backlight system as a feedback control mechanism to track the optimal operating frequency of the PT, so that the PT´s temperature effect is removed; hence, system efficiency and stability is improved. The design considerations are detailed, and the experimental results confirm the validity of the proposed control strategy

Keywords

digital phase locked loops; embedded systems; feedback; fluorescent lamps; lamp accessories; piezoelectric devices; power transformers; resonant invertors; CCFL; DPLL embedded controller; backlight electronic ballast; class-D resonant inverter; cold cathode fluorescent lamp; digital phase-locked-loop technique; feedback control; piezoelectric transformer; temperature effect; Circuits; Control systems; Digital control; Electronic ballasts; Feedback control; Frequency; Inverters; Optimal control; Phase locked loops; Temperature control; Backlight; cold cathode fluorescent lamp (CCFL); digital phase-locked loop (DPLL); electronic ballast; piezoelectric transformer (PT);

fLanguage

English

Journal_Title

Industrial Electronics, IEEE Transactions on

Publisher

ieee

ISSN

0278-0046

Type

jour

DOI

10.1109/TIE.2007.892733

Filename

4135422