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4th International Science, Social Science, Engineering and Energy Conference
11th-14th December, 2012, Golden Beach Cha-Am Hotel, Petchburi, Thailand
I-SEEC 2012
www.iseec2012.com
A Zero-Voltage Switching and Zero-Current Switching PWM
DC/DC SEPIC Converter for High Power LED Applications
B. Hiransinga,e1, T. Tongleamb,e2, C. Buasric,e3, A. Jangwanitlertd,e4
a,b
Department of Electronics Engineering, Faculty of Science and Technology,
Nakhon Pathom Rajabhat University, Nakhon Pathom, 73000, Thailand
c
Department of Electrical Engineering, Faculty of Engineering,
Thonburi University, Bangkok, 10160, Thailand
d
Department of Electrical Engineering, Faculty of Engineering,
King Mongkut’s Institute of Technology Ladkrabang, Bangkok, 10520, Thailand
e1
[email protected], [email protected],
e3
[email protected], [email protected]
Abstract
This paper presents the design of a zero-voltage switching (ZVS) and zero-current switching (ZCS) PWM
SEPIC dc/dc converter for high power LED applications. The proposed circuit using a novel lossless
commutation cell for high switching frequency operation. The most important property in this circuit is
the ability to regulate output power and voltage by Pulse-Width-Modulation (PWM), with constant
operating frequency, without load limitation and without sacrificing the lossless commutation. The
proposed circuit consists one main and one auxiliary switch under ZVS and ZCS conditions, respectively.
The switching frequency of the power MOSFETs is 100 kHz with Atmel AVR ATmega16
microcontroller for prototype. The simulation results obtained from the PSpice program have confirmed
the ZVS and ZCS conditions of the proposed circuit and confirmed the experimental results, with an input
voltage range of 9V to 15 V, an output voltage rang of 18V to 22V and an output power rating of up to
22 W. The output voltage and current waveforms also show a good response with the load.
Keywords: zero-voltage switching and zero-current switching; SEPIC converter; dc-dc converter; high power LED
1. Introduction
It has been of interest the development of dc/dc converters and switching power supply with high
efficiency, small size and weight, low cost, high power operation, high frequency, low harmonic and unity
power factor
In this paper, it is proposed a zero-voltage switching (ZVS) and zero-current switching (ZCS) PWM
SEPIC dc/dc converter for high power LED applications which provide non-dissipative switching in high
frequency and high efficiency.
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1.1. Structure of the proposed system
The circuit configuration of the proposed system is shown in Figure 1. The system is composed of five
main parts namely, AC power source, TRIAC dimmer, AC/DC full bridge rectifier, soft switching PWM
SEPIC dc/dc converter and high power LED load.
L
D1
D3
C1
Ls
AC
Sm
TRIAC
C
D4
R
TRIAC DIMMER
C
Dm
Cr
V
Do
Lr
Da Lm
o
Co
LED
Sa
D2
Vgsm Vgsa Auxiliary Circuit
BRIDGE RECTIFIER
PWM
AVR ATmega16
Microcontroller
Vref
Fig. 1. A zero-voltage switching (ZVS) and zero-current switching (ZCS) PWM SEPIC dc-dc converter for high power LED
applications
1.2. Soft Switching SEPIC dc/dc converter
The soft switching PWM SEPIC dc/dc converter is shown in Figure 2. In this circuit in shown in
Figure 2. (a) consist of a constant DC voltage source, SEPIC dc/dc converter with hard switching,
auxiliary circuit for soft switching and a load. Figure 2. (b) show the theoretical wave form
Vg,Sa
L
Vin
C
Sm
Dm
Cr
Do
Lr
Da
Lm
Sa
Co
RL
Vo
Vg,Sm
t
Vcr
t
t
ILr
IL+Ism
Ism
t
Auxiliary Circuit
t0
(a)
t1
t2 t3 t4
t5
t6
t7
t
(b)
Fig. 2. (a) A zero-voltage switching (ZVS) and zero-current switching (ZCS) PWM SEPIC dc-dc converter ; (b) Theoretical
waveforms
In this converter the auxiliary switch Sa of the feedback resonant circuit is closed in the ZCS form to
provide the soft switching condition from the main switch Sm which responsible by PWM characteristics.
Author name / Procedia Engineering 00 (2011) 000–000
2. Simulation Results
The proposed circuit simulation with PSpice program. Figure 3(a) show voltage and current waveform
at switch and Figure 3 (b) show output voltage at full load
(a)
(b)
Fig. 3.simulation (a) voltage and current waveform at switch Sm (b) output voltage at full load
3. Experimental Results
The experiment prototype of the proposed circuit is shown in Figure 4. It is waveform of Pulse Width
Modulation (PWM) signal with Atmel AVR ATmega16 microcontroller switching frequency 100 kHz
49% duty cycle
Fig. 4. PWM signal Atmel AVR ATmega16 microcontroller
4. Conclusions
This paper presents the design of a zero-voltage switching (ZVS) and zero-current switching (ZCS) PWM
SEPIC dc/dc converter for high power LED applications. The proposed circuit using a novel lossless
commutation cell for high switching frequency operation. The most important property in this circuit is
the ability to regulate output power and voltage by Pulse-Width-Modulation (PWM), with constant
operating frequency, without load limitation and without sacrificing the lossless commutation. The
proposed circuit consists one main and one auxiliary switch under ZVS and ZCS conditions, respectively.
The switching frequency of the power MOSFETs is 100 kHz with Atmel AVR ATmega16
microcontroller for prototype. The simulation results obtained from the PSpice program have confirmed
the ZVS and ZCS conditions of the proposed circuit and confirmed the experimental results, with an input
voltage range of 9V to 15 V, an output voltage rang of 18V to 22V and an output power rating of up to
22 W. The output voltage and current waveforms also show a good response with the load.
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