Download a high step-down multiple output converter with wide input voltage

A HIGH STEP-DOWN MULTIPLE OUTPUT CONVERTER WITH WIDE
INPUT VOLTAGE RANGE BASED ON QUASI TWO-STAGE
ARCHITECTURE AND DUAL-OUTPUT LLC RESONANT CONVERTER
ABSTRACT:
In this letter, a quasi two-stage architecture is proposed for wide input
voltage range (voltage ranges _ 1:2) and high step-down multiple output
conversion. A dc-DCX, which operates as a dc–dc converter with regulated output
when the input voltage is low and as a dc–dc transformer with unregulated output
when the input voltage is high, is adopted in the first stage to provide optimized
intermediate dc-bus voltages for the second-stage pointof- load converters. The
input and output of the dc-DCX are in series and connected to the total input
voltage. Hence, part of the input power is directly transferred to the intermediate
bus without conversion. The devices’ voltage stresses and the transformer turns
ratio of the dc-DCX are reduced by using the proposed quasi two-stage
architecture. Thus, the conversion efficiency is improved significantly.
Furthermore, a dual-output LLC resonant converter with hybrid center-tapped and
full-bridge rectifier is proposed for the dc-DCX to achieve high efficiency and high
power density. A 100-W prototype with three outputs is built and tested to verify
the analysis.
INTRODUCTION:
The two-stage architecture is a good candidate for the wide and-high input,
multiple-and-low output applications. It has been proven that, although additional
loss is introduced by the first-stage bus converter, the efficiency can still be
improved with a very-high-frequency second-stage point-of-load (PoL) converter
by reducing the intermediate bus voltage and using low-voltage-rating devices.
If the input voltage range is narrow, a very high efficiency unregulated dc–dc
transformer (DCX) can be employed as the front-end converter, because the
unregulated converter can be designed at its optima operation point to achieve the
highest efficiency.
The two-stage architecture is a good candidate for the wideand- high input,
multiple-and-low output applications . It has been proven that, although additional
loss is introduced by the first-stage bus converter, the efficiency can still be
improved with a very-high-frequency second-stage point-of-load (PoL) converter
by reducing the intermediate bus voltage and using low-voltage-rating devices.
If the input voltage range is narrow, a very high efficiency unregulated dc–dc
transformer (DCX) can be employed as the front-end converter, because the
unregulated converter can be designed at its optima operation point to achieve the
highest efficiency .However, if the bus voltage range is wide, the output voltage
regulation is required for the bus converter to provide an optimized intermediate dc
bus voltage for the PoL converters.
Otherwise, the intermediate bus voltage will vary within a wide range, and hence
high efficiencywould not be achieved for the second-stage PoL converters.
However, high efficiency within a wide input voltage range is difficult to achieve
for a dc–dc converter with full voltage regulation .
A tradeoff between the efficiency of the two stages is necessary to implement
optimized efficiency of the whole system. In, a sigma converter based on a DCX
and a dc–dc converter is proposed for high step-down PoL converter. The sigma
converter seems to be a good solution for the bus converter because voltage
regulation and high efficiency can be achieved .
EXISTING SYSTEM:
Synchronous rectifiers are used to improve the efficiency. Considering the voltage
stresses on the switches, a full-bridge rectifier is used for the VBus1, and a centertapped rectifier is used for the VBus2. Therefore, two secondary windings and six
synchronous-rectifying switches have to be used in the front-end converter
PROPOSED SYSTEM:
A multiple output dc–dc converter based on quasi two-stage architecture has been
proposed in this letter. By connecting the input and output of the dc-DCX in series,
20%–25% ratio of the total input power is directly fed to the intermediate bus
without conversion. Hence, the devices’ voltage stresses and transformer turns
ratio of the dc-DCX can be reduced and high efficiency achieved for the front-end
bus converter. By adopting the semi regulation control scheme, optimized
intermediate bus voltages are provided for the second-stage PoL converters while
considering the tradeoff between the efficiencies of the frontend converter and PoL
converters.
ADVANTAGES:
 Less number of switches.
BLOCK DIAGRAM:
Full bridge
inverter
resonant
Circuit
Centre
tapped
transformer
Output 1
Synchronous
rectifier
Gate driver circuit
BUFFER
circuit
5 V DC
INPUT
DC supply
PIC controller
circuit
Output 2
12 V
DC
TOOLS AND SOFTWARE USED:
 MPLAB – microcontroller programming.
 ORCAD – circuit layout.
 MATLAB/Simulink – Simulation
APPLICATIONS:
 Aerospace and telecommunication applications.
 Satellite power system
CONCLUSION:
A multiple output dc–dc converter based on quasi two-stage architecture has
been proposed in this letter. By connecting the input and output of the dc-DCX in
series, 20%–25% ratio of the total input power is directly fed to the intermediate
bus without conversion. Hence, the devices’ voltage stresses and transformer turns
ratio of the dc-DCX can be reduced and high
efficiency achieved for the front-end bus converter. By adopting the semiregulation
control scheme, optimized intermediate bus voltages are provided for the secondstage PoL converters while considering the tradeoff between the efficiencies of the
frontend converter and PoL converters. To improve the power density and reduce
the cost, a hybrid center-tapped and full-bridge rectifier has been proposed for the
dual-output LLC resonant converter. Experimental results on a 48–85 V input and
three outputs (10 V/8A, 5 V/2A, and 3.3 V/2A) prototype indicate that high
efficiency within wide input voltage (voltage ranges _1:2) and load ranges has
been achieved with the proposed solution.
REFERENCES:
[1] S. Luo and I. Batarseh, “A review of distributed power systems part I: DC
distributed power system,” IEEE Aerosp. Electron. Syst. Mag., vol. 20, no. 8, pp.
5–16, Aug. 2005.
[2] Z. Varadi, V. Gorocz, and J. Szabo, “Power subsystem for small satellites with
unified operational mode controller,” in Proc. 2nd IEEE Int. Conf. Space Technol.,
2011, pp. 1–4.
[3] F.Musavi, M. Craciun, D. S. Gautam,W. Eberle, andW. G. Dunford, “An LLC
resonant DC–DC converter for wide output voltage range battery charging
applications,” IEEE Trans. Power Electron., vol. 28, no. 12, pp. 5437–5445, Dec.
2013.