MISO LUO POSITIVE OUTPUT DC-DC CONVERTER FOR
SUSTAINABLE ENERGY APPLICATIONS
1
RAOSAHEB D. THOMBARE, 2NACHIKETA B. DESHMUKH, 3DAGADU S. MORE
1,2,3
Department of Electrical Engineering, Walchand College of Engineering, Sangli, India
E-mail: mr_thombare@rediffmail.com; nachiketa.deshmukh@yahoo.in;dsm.wce@gmail.com
Abstract- Renewable energy resources have astonishing capabilities to fulfill ever increasing future demands. Changing
climatic conditions is a major inherent drawback associated with it and MPPT (Maximum Power Point Tracking) is one of the
techniques used to overcome it (wind and solar). This paper has proposed a positive output super lift Luo converter which is
integrated with multiple sources for reducing passive elements. The proposed topology can be used for low or high power
applications and can be extended to interface any number of sources having different characteristics. In case used for
renewable sources’ grid integration, number of active switches required will be only two for any number of sources. It also has
a bidirectional battery storage port that improves reliability of the system. These systems are simulated in MATLAB software
environment and results are obtained.
Keywords- Luo converter, MISO Luo converter, Bidirectional battery port, MPPT, Renewable energy sources
passive elements. Proposes a novel half bridge
converter based topology that interfaces four power
ports: two sources, one bidirectional storage port, and
one isolated load port. While connecting multiple
renewable sources, it cannot extract maximum power
from each source and it is only suitable for low-power
applications since it has half-bridge topology.
Proposes new extendable single-stage multi-input
boost converter which can operate in both DC–DC and
DC–AC modes and has two bidirectional ports for
battery storage. This topology not only fails to provide
common ground to source and load but also becomes
complex when it handles three phase load. Modeling
and simulation of Solar PV system with perturb and
observe MPPT algorithm is studied in. In a VSWECS
(Variable Speed Wind Energy Conversion System)
with MPPT is considered.
I. INTRODUCTION
The voltage-lift (VL) technique is a popular method
used in electronic circuit design. This technique was
also used in DC-DC converters to boost the source
voltage into a higher level with high power efficiency
and high power density due to reduced effect of
parasitic element. The positive output super lift Luo
converter is a DC-DC converter having high voltage
transfer gain, high power density, high efficiency,
reduced ripple in voltage and current. These
converters are widely used in computer peripheral
equipment, industrial applications and switch mode
power supply, especially for high voltage applications.
A positive output Luo converter for photovoltaic
system with model predictive control algorithm is
designed and simulated in. The super lift converter for
photovoltaic system is designed and simulated for AC
load and grid in. A solar panel power system is
designed using the super lift Luo converter with a
closed loop control to obtain the desired output voltage
in. However, number of passive elements goes on
increasing as number of sources increase making
system bulky and cost inefficient.
This paper has proposed a positive output super lift luo
converter which is integrated to interface multiple
sources for reducing passive elements. The proposed
topology can be used for low or high power
applications and can be extended to interface any
number of sources having different characteristics. In
case used for renewable sources’ grid integration,
number of active switches required to interface any
number of sources will be two only. It also has a
bidirectional battery storage port that can be charged
from any source while supplying load or discharge
with any source and hold energy for future utilization.
Solar-Wind based Dual-Input Converter is proposed
for telecom applications in. A three-input DC-DC
boost converter with bidirectional battery interface is
proposed in. However, topologies in are not
extendable to more number of input sources. MISO
(Multiple Input Single Output) systems based on flux
addition concept are proposed in. As the number of
sources increases, system becomes difficult to handle.
Different MISO topologies are developed for sepic
and cuk converter in. As number of sources goes on
increasing the circuit components are added linearly
(especially control switches). Some topologies should
have all sources at same voltage level. A MISO
DC-DC converter along with its control scheme is
proposed and analyzed in. It requires large number of
This paper is structured as follows. Section II
describes basic concept of positive output super lift
Luo converter. Section III discusses working of MISO
positive output super lift Luo converter. Section IV
gives operating modes of MISO positive output super
lift Luo converter with battery port. Section V
discusses renewable energy sources taken into
consideration i.e. wind and solar. Section VI contains
simulation results. Section VII gives conclusion of the
proposed system.
Proceedings of 9th ISERD International Conference, Lisbon, Portugal, 23rd August, 2015, ISBN: 978-93-85465-71-0
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MISO Luo Positive Output Dc-Dc Converter For Sustainable Energy Applications
II. POSITIVE OUTPUT SUPER LIFT LUO
CONVERTER
III. MISO POSITIVE OUTPUT SUPER LIFT
LUO CONVERTER
The Luo converters are connected in such a way that
the output side capacitor remains common. A diode
and inductor are kept individual for each source.
Charging capacitor is common for all sources
connected above each other. E.g. C1 is common for
source 1 and source 2, as shown in Fig. 4.
In stage 1, when controlled switches are closed, diodes
D2, D3, D5, and D6 are turned on. Source voltage
charges parallel combination of inductor and
capacitor. E.g. source 1 charges L1 and C1 whereas
source 2 charges L2 and C1. The output stage capacitor
CO supplies load current, as shown in Fig. 5.
Fig 1: Positive output super lift Luo converter
In stage 2, when controlled switches are opened,
diodes D1 and D4 are turned on. Energy stored by all
passive elements, along with sources, is dumped in
output stage capacitor CO. So the output voltage is
boosted, as shown in Fig. 6.
Fig. 1 shows the basic topology of positive output
super lift Luo converter. It has two operating stages
depending on switching state of SW1.
In stage 1, when the switch is closed, the supply
voltage increases the current through the inductor L1
and the capacitor C1 gets charged. The load current is
maintained constant by the discharge of the capacitor
CO during this period, as shown in Fig. 2.
In stage 2, when the switch is opened, the stored
energy in the inductor L1 and C1, along with source 1,
supplies the load current and CO is charged to produce
the boosted voltage across the load, as shown in Fig. 3.
Fig 4: MISO positive output super lift Luo converter
Fig 2: Positive output super lift Luo converter
(Operating stage 1)
Fig 3: Positive output super lift Luo converter
(Operating stage 2)
Fig 5: MISO positive output super lift Luo converter
(Operating stage 1)
Proceedings of 9th ISERD International Conference, Lisbon, Portugal, 23rd August, 2015, ISBN: 978-93-85465-71-0
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MISO Luo Positive Output Dc-Dc Converter For Sustainable Energy Applications
In stage A, source 1 charges L1 and C1 through battery
whereas source 2 charges L2 and C2 through battery.
Co supplies load power.
In stage B, L1, C1 and L2, C2, along with sources,
discharge in Co and we get boosted voltage across
load. Battery retains energy stored.
Here both the sources charge battery. Even if one
source is inactive, the other source can charge battery.
Fig. 9 shows active part of proposed circuit for mode
2.
C. Mode 3
Here SW3 and SW4 are turned on. D5 and D6 are
reverse biased by battery voltage.
In stage A, source 1 charges L1 and C1 whereas source
2 charges L2 and C2. Battery is also discharged in L1,
L2 and C1, C2 as it comes in series circuit. Co supplies
load power.
Fig 6: MISO positive output super lift Luo converter
(Operating stage 2)
In stage B, L1, C1 and L2, C2, along with sources,
discharge in Co and we get boosted voltage across
load. Here battery is discharged to load when sources
do not have enough energy to drive it. This mode also
works when one of the sources is inactive. Fig. 10
shows active part of proposed circuit for mode 3.
IV. MISO POSITIVE OUTPUT SUPER LIFT
LUO CONVERTER WITH BATTERY PORT
The proposed multiple input Luo converters can be
integrated with battery in such a way that the overall
system can stand alone. Fig. 7 shows MISO Luo
converter with two sources and one bidirectional
battery port. However, this topology can be extended
to interface any number of sources in addition to one
bidirectional battery port.
We propose three working modes of the system.
1. Sources are supplying load without battery
interference
2. One or both the sources are charging battery
3. Battery is discharging with one or both the sources
In the proposed circuit, SW1 and SW2 are operating
switches. SW3, SW4 are control switches that decide
operating mode of the circuit. Every mode has two
stages that are defined by the conditions of SW1 and
SW2. When SW1 and SW2 are on, the circuit works in
stage A. When SW1 and SW2 are off, circuit works in
stage B.
Fig 7: MISO positive output super lift luo converter with
battery port
A. Mode 1
Here SW4 is turned on. D5 is forward biased by source
voltages. In stage A, source 1 charges L1 and C1
whereas source 2 charges L2 and C2. Co supplies load
power. In stage B, L1, C1 and L2, C2, along with
sources, discharge in Co and we get boosted voltage
across load. Here battery is neither charged nor
discharged and hence retains its state of charge. This
state can be fully charged where it can supply load
power in case of emergency. This mode can also be
realized using SW3 and D6. Fig. 8 shows active part of
proposed circuit for mode 1.
B. Mode 2
Here only D5 and D6 conduct. SW3 and SW4 are
turned off.
Fig 8: Active part of topology in mode 1
Proceedings of 9th ISERD International Conference, Lisbon, Portugal, 23rd August, 2015, ISBN: 978-93-85465-71-0
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MISO Luo Positive Output Dc-Dc Converter For Sustainable Energy Applications
Fig 9: Active part of topology in mode 2
Fig11: Perturb and Observe MPPT
E. Wind source and its MPPT
Wind energy is a renewable, clean, and free energy
source for energy production. Wind energy conversion
system (WCES) requires no connection to an existing
power source, and they could be combined with other
power sources to increase system reliability and could
be installed and upgraded as wind firm; more wind
turbine could be added as power demand increases.
The overall system cost can be further reduced by
optimal control of high efficiency power electronic
converters to extract maximum power in accordance
with atmospheric conditions.
Fig 10: Active part of topology in mode 3
I.
MPPT of the WTG (Wind Turbine Generator) ensures
that it operates at the maximum value of Cp as shown
in Fig. 12. One of the methods of estimating the
maximum power point is by knowing the wind turbine
parameters and measuring the rotational speed of the
rotor. It is also possible to determine maximum power
point without the knowledge of turbine parameters as
well as rotor speed. In this scheme, the rotational
speed of the generator is dynamically modified in
accordance with magnitude and direction of active
power flow [15].
RENEWABLE ENERGY SOURCES
(WIND AND SOLAR)
D. Solar source and its MPPT
A prime attraction of PV systems is that it produces
electrical energy by directly transforming a free
renewable source of energy into electrical energy.
The efficiency of solar cells depends on many factors
such
as
temperature,
insolation,
spectral
characteristics of sunlight, shadow, and so on.
All MPPT methods follow the same goal which is
maximizing the PV array power output by tracking the
maximum power in every operating condition. In this
algorithm a slight perturbation is introduced in the
system. This perturbation causes the power of the solar
module to change. If the power increases due to the
perturbation ( / is positive) then the perturbation
is continued in same direction. After the peak power is
reached the power at the next instant decreases ( /
is positive) and hence after that the perturbation
reverses as shown in Fig. 11. When the steady state is
reached the algorithm oscillates around the peak point.
In order to keep the power variation small the
perturbation size is kept very small. It is observed that
there some power loss due to this perturbation also the
fails to track the power under fast varying atmospheric
conditions. But still this algorithm is very popular and
simple [14].
Fig 12: MPPT for WCES
II.
SIMULATION RESULTS
F. MISO Luo converter
The circuit is simulated for two solar and two wind
Proceedings of 9th ISERD International Conference, Lisbon, Portugal, 23rd August, 2015, ISBN: 978-93-85465-71-0
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MISO Luo Positive Output Dc-Dc Converter For Sustainable Energy Applications
sources. One solar and one wind source are made
inactive after three seconds. Fig. 13 shows the solar
insolation input given to solar sources. Fig. 14 shows
the temperature input given to solar sources. Fig. 15
shows the wind speed input given to wind sources.
The values of circuit components used for simulation
are as follows: L (ALL) = 3mH; C (ALL) =1mF; CO=5mF;
switching frequency = 1 kHz; R (Load) =30 Ohm.
G. MISO Luo converter with battery
The circuit is simulated for two sources - one wind and
one solar. Insolation input to the solar source is 1000
W/m2. Temperature input given to the solar source is
35 oC. Wind speed input given to the wind source is 12
m/s.
The values of circuit components used for simulation
are as follows: L (ALL) = 3mH; C (ALL) =1mF; CO=5mF;
switching frequency = 1 kHz; R (Load) =30 Ohm.
Battery source is rated at 150 V, 15 Ah.
Fig. 16 shows the scaled output current, voltage,
power of the system. The output plot given is scaled as
follows: Power is scaled as 1:1000. Voltage is scaled
as 1:100. Current is scaled as 1:10.
The topology is operated in mode 1 for 0-2 sec;
operated in mode 2 for 2-4 sec; operated in mode 3 for
4-6 sec.
Fig. 17 shows the scaled output current, voltage,
power of the system. The output plot given is scaled as
follows: Power is scaled as 1:1000. Voltage is scaled
as 1:100. Current is scaled as 1:10. Fig. 18 shows
variation in battery parameters i.e. voltage, current and
initial state of charge (ISOC).
Fig13: Insolation input to solar sources
Fig 14: Temperature input to solar sources
Fig17: MATLAB results for output of the MISO Luo system
with battery port
Fig 15: Wind speed input to wind sources
Fig18: MATLAB results for variation in battery parameters
CONCLUSION
A new multiple input single output luo converter based
topology is proposed and simulated in this paper. It is
also integrated with bidirectional battery port.
It can be extended to interface any number of sources
having different characteristics and voltage levels.
Fig 16: MATLAB results for output of the MISO Luo
converter
Proceedings of 9th ISERD International Conference, Lisbon, Portugal, 23rd August, 2015, ISBN: 978-93-85465-71-0
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MISO Luo Positive Output Dc-Dc Converter For Sustainable Energy Applications
Electronics and Applications (ISIEA2012),September 23-26
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sources.
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Proceedings of 9th ISERD International Conference, Lisbon, Portugal, 23rd August, 2015, ISBN: 978-93-85465-71-0
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