single-switch led driver with the function of power factor...
TRANSCRIPT
Single-switch LED Driver with the Function of Power
Factor Correction
Geun-Yong Park and Gang-Youl Jeong*
Department of Electronic Information Engineering, Soonchunhyang University
22 Soonchunhyang-Ro, Shinchang-Myun, Asan-Si, Choongnam, South Korea
Abstract.This paper proposes asingle-switch LED driver with the function of
power factor correction (PFC). The proposed driver uses a single-switch power
conversion circuit topology which are the boost converter and the flyback
converter into. The proposed converter can be more simplified than the
conventional LED drivers. An operation principle is explained, briefly, and
exprimental results are shown to verify the performance of the proposed
converter.
Keywords: Single-switch LED driver, boost converter, fly back converter.
1 Introduction
The conventional lamps have many environmental problems such as much lead and
mercury, a lot of power consumption, and short lifetimes. However, because light-
emitting diodes (LEDs) have many advantages such as small size, high luminous
efficiency, long lifetime, fast response, and excellent color rendering, they have been
widely used in many lighting applications. LEDs are environmentally friendly devices
compared with conventional fluorescent lamps that require mercury and may produce
pollution. Therefore, in pursuit of energy-saving and pollution free light sources,
LEDs have gradually replaced fluorescent lamps and have become increasingly and
more widely used [1-8]. Therefore this paper presents a simple single-switch LED
driver with the function of PFC, which can operate LED-lighting device, effectively.
2 Operational principles
Figure 1 shows the main power circuit of the proposed driver. The proposed driver is
composed of a power circuit and a control circuit. Figure 2 shows the theoretical
waveforms of the key parts of the proposed driver.
The proposed driver operates in critical conduction mode (CCM). This is different
from the conventional single-switch LED drivers that operate in either continuous
conduction mode or discontinuous conduction mode. The proposed driver operating
with the CCM has an advantage in that it can achieve zero-voltage switching without
any additional active snubber circuit. Other advantages include a lower THD of the
Advanced Science and Technology Letters Vol.51 (CES-CUBE 2014), pp.20-23
http://dx.doi.org/10.14257/astl.2014.51.05
ISSN: 2287-1233 ASTL Copyright © 2014 SERSC
line current, lower turn-off switching losses, and lower conduction losses due to a
smaller peak inductor current when compared with conventional single-stage LED
converters [6].
Fig. 1. The main power circuit of the proposed single-switch LED driver.
Fig.2. The theoretical waveforms of the key parts of the proposed converter.
D o
S
R
C o
L m
v p v s
iD o
im
V o
v A C V inC inE M I
F ilte r
iA C
I o
ip
v d s
D C -D C B o o s t C o n v e r te rF ly b a c k C o n v e r te r
v A C
V in
iA C
i p
t
T s
v s ,
v g s
tto n t o ff
t
v p
V in
t
-V o /n
v d s
I oV o ,
im
t
I p , p e a k= k V D C = k |v A C |
t
v A C
iA C
V in
i p
t
I p = I p , p e a k2
1
T
i p n iD o
Advanced Science and Technology Letters Vol.51 (CES-CUBE 2014)
Copyright © 2014 SERSC 21
Figure 3 shows the operation modes of the proposed single-switch LED driver in a
positive half cycle of the AC input source, where the bold line represents the
conduction line and the dotted line represents the no conduction line.
(a) Mode A (b) Mode B
Fig.3. The operation modes of the proposed single-stage LED converter.
If the AC input voltage is in a negative half cycle, the rectified DC input voltage
Vin is the same as when the AC input voltage is at a positive half cycle due to the
operation of the FB diode rectifier (Vin=|vAC|). Therefore, the operations of the driver
at a negative half cycle are also the same as in modes A and B. Thus, the f of the
proposed driver in a negative half cycle of the AC input voltage is omitted.
3 Experimental results
Fig.4. The experimental waveforms of the AC input voltage and current, and the DC output
voltage and current of the proposed LED converter.
Fig.5. The experimental waveforms of the key parts of the proposed converter at a line
frequency scale.
C o
D o
V o
C in
v sv p
R:V in
L m
N p N S
v A C
ip
iA C
v d sS
im
iD o I o
C o
D o
V o
C in
v sv p
R:V in
L m
N p N S
v A C
ip
iA C
v d sS
im
iD o I o
Advanced Science and Technology Letters Vol.51 (CES-CUBE 2014)
22 Copyright © 2014 SERSC
Fig.6. The experimental waveforms of the key parts of the proposed converter at a switching
frequency scale.
To validate the feasibility of the proposed LED converter, a prototype converter
was constructed and tested. Figures 4~6 show the experimental waveforms of the key
parts of the proposed driver. These show the good performance of the proposed driver.
4 Concluding remarks
In this paper, a single-switch LED driver with the function of PFC has been proposed,
and the operational principle and the experimental result have been described, briefly,
and shown to verify the feasibility of the proposed driver, respectively. The proposed
driver has good performance as an LED driver.
References
1. Doshi, M. and Zane, R.: Control of Solid-State Lamps Using a Multiphase Pulse width
Modulation Technique, IEEE Trans. on Power Elec., Vol. 25, No. 7, pp. 1894-1904 (2010)
2. Lee, B., Kim, H. and Rim, C.: Robust Passive LED Driver Compatible With Conventional
Rapid-Start Ballast, IEEE Trans. on Power Elec., Vol.26, No. 12, pp. 3694-3706(2011)
3. Hsieh, Y. T., Liu, B. D., Wu, J. F., Fang, C. L., Tsai, H. H. and Juang, Y. Z.: A High-
Dimming-Ratio LED Driver for LCD Backlights, IEEE Trans. on Power Elec., Vol.27, No.
11, pp. 4562-4570(2012)
4. Moo, C. S., Chen, Y. J. and Yang, W. C.: An Efficient Driver for Dimmable LED Lighting,
IEEE Trans. on Power Elec., Vol.27, No. 11, pp. 4613-4618(2012)
5. Chen, N. and Chung, H. S. H.: An LED Lamp Driver Compatible With Low- and High-
Frequency Sources, IEEE Trans. on Power Elec., Vol.28, No. 6, pp. 2551-2568(2013)
6. Liu, K. H. and Lin, Y. L.: Current Waveform Distortion in Power Factor Correction Dircuits
Employing Discontinuous-Mode Boost Converters, In Proceeding of the IEEE Power
Electronics Specialists Conference ’89, pp. 825-829, IEEE Press, Milwaukee (1989)
Advanced Science and Technology Letters Vol.51 (CES-CUBE 2014)
Copyright © 2014 SERSC 23