ABSTRACT:
Poor power
quality, slow dynamic response, high device stress, harmonic rich, periodically
dense, peaky, distorted input current are the major problems that are
frequently encountered in conventional switched mode power supplies (SMPSs)
used in computers. To mitigate these problems, it is proposed here to use a
nonisolated bridgeless buck-boost single-ended primary inductance converter
(SEPIC) in discontinuous conduction mode at the front end of an SMPS. The
bridgeless SEPIC at the front end provides stiffly regulated output dc voltage
even under frequent input voltage and load variations. The output of the front
end converter is connected to a half-bridge dc–dc converter for isolation and
also for obtaining different dc voltage levels at the load end that are needed
in a personal computer. Controlling a single output voltage is able to regulate
all the other dc output voltages as well. The design and simulation of the
proposed power supply are carried out for obtaining an improved power quality
that is verified through the experimental results.
KEYWORDS:
1. Bridgeless converter
2. Computer power supply
3.
Input current
4.
Power factor correction
(PFC)
5.
Power quality
SOFTWARE:
MATLAB/SIMULINK
SCHEMATIC DIAGRAM:
Fig.
1. Schematic diagram of the PFC converter based SMPS.
EXPECTED SIMULATION RESULTS:
Fig.
2. (a) Performance of the computer power supply at rated condition. (b) Input
current and its harmonic spectrum at full load condition. (c)Waveform across various
components of the bridgeless converter.
Fig.
3. (a) Performance of the computer power supply at light load condition.
(b)
Input current and its harmonic spectrum at light load condition.
CONCLUSION:
A bridgeless nonisolated SEPIC based
power supply has been proposed here to mitigate the power quality problems
prevalent in any conventional computer power supply. The proposed power supply
is able to operate satisfactorily under wide variations in input voltages and
loads. The design and simulation of the proposed power supply are initially
carried to demonstrate its improved performance. Further, a laboratory
prototype is built and experiments are conducted on this prototype. Test
results obtained are found to be in line with the simulated performance. They
corroborate the fact that the power quality problems at the front end are
mitigated and hence, the proposed circuit can be a recommended solution for
computers and other similar appliances.
REFERENCES:
[1] D. O. Koval and C. Carter, “Power
quality characteristics of computer loads,” IEEE Trans. Ind. Appl., vol.
33, no. 3, pp. 613–621, May/Jun. 1997.
[2] A. I. Pressman,K.Billings, and T.
Morey, Switching Power SupplyDesign, 3rd ed. New York, NY, USA: McGraw
Hill, 2009.
[3] B. Singh, B. N. Singh, A. Chandra,
K. Al-Haddad, A. Pandey, and D. P. Kothari, “A review of single-phase improved
power quality AC-DC converters,” IEEE Trans. Ind. Electron., vol. 50,
no. 5, pp. 962–981, Oct. 2003.
[4] K. Mino, H. Matsumoto, Y. Nemoto, S.
Fujita, D. Kawasaki, R. Yamada, and N. Tawada, “A front-end converter with high
reliability and high efficiency,” in Proc. IEEE Conf. Energy Convers. Congr.
Expo., 2010, pp. 3216–3223.
[5] J.-S. Lai, D. Hurst, and T. Key,
“Switch-mode supply power factor improvement via harmonic elimination methods,”
in Proc. IEEE 6th Annu. Appl. Power Electron. Conf. Expo., 1991, pp.
415–422.
