A simple PWM method for improving lamp current crest factor of valley-filled electronic ballast

作者：Lee Zhi Ren; Hsiao Horng Ching

来源：International Journal of Circuit Theory and Applications, 2010, 38(3): 291-305.

DOI：10.1002/cta.573

• PWM
• current crest factor
• valley-filled electronic ballast
• power factor
• duty ratio
• THD

In this paper, a PWM method to improve the lamp current crest factor (CCF) of the valley-tilled electronic ballast (VFEB) is presented. The VFEB has merits of high power factor, simple structure, and low cost. However, it results in an excessive CCF, which will shorten the lifetime of low-pressure discharge lamp. The proposed method controls switching duty ratio by feeding forward the dc-link voltage waveform of VFEB. It decreased the duty ratio with rising of dc-link voltage. Therefore, the proposed method could restrain the lamp peak current and improve the lamp CCF. The control block diagram and basic theory are introduced to improve the CCF. The computer simulations verify the proposed method and derive a minimum lamp CCF. The experimental results demonstrate that the lamp CCF was reduced from 1.9 to 1.58, the ac line power factor is 96%, and the input current THD is 29.3%. The fixed switching frequency operation gains a satisfactory power quality.

• 出版日期2010-4