INTERNATIONAL CONFERENCE ON RENEWABLE AND SUSTAINABLE ENERGY (ICRSE-13)
Jose. J. and Jayanand B., Vol. 2, Special Issue, pp. 72-76, 2014
Simulation and Implementation of Superlift Luo Converter
Josily Jose* and Jayanand B.
Department of Electrical and Electronics, Government Engineering College, Idukki, Kerala,India
*Corresponding author: jose.josily@gmail.com
Abstract—Voltage lift technique is a popular method widely
used in electronic circuit design. However the voltage
increases stage by stage along arithmetic progression. But
with a super-lift converter, the output increases stage by
stage along a geometric progression. Thus it effectively
enhances the transfer gain in power series. This paper
presents the development of PI control capable of providing
good static and dynamic performance. MATLAB software is
used to study the dynamic characteristics and analyze the
closed loop performances of these converters with resistive
load under supply and load disturbances.DAC card is used
for the hardware implementation of positive output
elementary super lift Luo converter and its PI control. The
simulation and experimental results closely match with
each other and highlight the feasibility and validity of the
developed control scheme.
Index Terms–DC-DC Converter, PI control, DAC card
I. INTRODUCTION
DC to DC converters are important in portable electronic
devices such as cellular phones and laptop computers, which
are supplied with power from batteries. Such electronic
devices often contain several subcircuits which each require
unique voltage levels different than supplied by the battery
(sometimes higher or lower than the battery voltage, or even
negative voltage). Additionally, the battery voltage declines
as its stored power is drained. DC to DC converters offer a
method of generating multiple controlled voltages from a
single variable battery voltage, thereby saving space instead
of using multiple batteries to supply different parts of the
device.
Luo converters are DC-DC Switching Mode Boost converters.
A boost converter (step-upconverter) is a power converter
with an output dc voltage greater than its input dc voltage.
Luo converters are a class of converters providing a high gain
with relatively lesser number of components. Although Luo
converters provide a high gain, when cascaded, the gain
increases stage by stage only in Arithmetic
progression i.e. these converters uses the voltage lift (VL)
technique. In order to solve this discrepancy in the Classical
Luo Converters, another class of converters called Super-lift
Luo Converters were developed. While the positive aspects
of the Classical Luo Converters are retained in Super-lift
converters, Super-lift converters also have the advantage
that the gain in this converter increases in geometric
progression, stage by stage.
II. POSITIVE OUTPUT SUPERLIFT LUO CONVERTERS
The positive output elementary super lift Luo converter is a
new series of DC-DC converters possessing high-voltage
transfer gain, high power density; high efficiency, reduced
ripple voltage and current . These converters are widely used
in computer peripheral equipment, industrial applications
and switch mode power supply, especially for high voltagevoltage projects. The positive output elementary super lift
Luo converter performs the voltage conversion from positive
source voltage to positive load voltage. The gain in this
converter increases in geometric progression, stage by stage.
It effectively enhances the voltage transfer gain in power
series. Each circuit has one switch, n inductors, 2n capacitors,
and (3n-1) diodes. The conduction duty ratio is d, switching
frequency is f (period T = 1/ f ) the load is resistive load R .
The input voltage and current are Vin and Iin, output voltage
and current are VO and IO . Assume no power losses during
the conversion process, Vin × Iin = VO × IO . The voltage
transfer gain is G. G = VO/ Vin. The first three stages of
positive output super-lift converters are shown. For
convenience to explain, we call them as
a) Elementary circuit (n = 1)
b) Relift circuit (n = 2)
c) Triple-lift circuit (n = 3) respectively.
The positive output elementary super lift Luo converter is
shown. in Fig. 1. It includes dc supply voltage Vin, capacitors
C1 and C2 , inductor L1, power switch (n-channel MOSFET) S,
freewheeling diodes D1 and D2 and load resistance R.
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INTERNATIONAL CONFERENCE ON RENEWABLE AND SUSTAINABLE ENERGY (ICRSE-13)
Jose. J. and Jayanand B., Vol. 2, Special Issue, pp. 72-76, 2014
i L1 
Vo 
Vin
V  2Vin
dT  o
dT
L1
L1
(1)
2d
Vin
1 d
(2)
The voltage transfer gain is
G
Figure 1. Positive Output Elementary Superlift Luo converter
In the description of the converter operation, it is assumed
that all the components are ideal and also the positive
output elementary super lift Luo converter operates in a
continuous conduction mode. Figs. 2 and 3 shows the modes
of operation of the converter.
Vo
2d

Vin
1 d
(3)
The input current iin is equal to (iL1 + iC1) during switching on
and only equal to iL1 during switching-off. Capacitor current
iC1 is equal to iL1 during switching-off. In steady state, the
average charges across capacitor C1 should not change. We
have the following relations:
iin-off  iL1off  iC1off
(4)
iinon  iL1on  iCion
(5)
dTiC1on  (1  d )TiC1off
(6)
If inductance L1 is large enough, iL1 is nearly equal to its
average current iL1. Therefore
iinoff  iC1off  I L1
Figure 2. Mode I operation
In Fig. 2 when the switch S is closed, voltage across capacitor
C1 is charged to Vin . The current iL1 flowing through inductor
L1 increases with voltage Vin.
iinon  I L1 
iC1on 
(7)
I
1 d
I L1  L1
d
d
(8)
1 d
I L1
d
(9)
and average input current
Iin  diinon  (1  d )iinoff  I L1  (1  d )I L1  (2  d )I L1
(10)
Considering T = 1/ f and
Vin  1  d  Vo  1  d 



 R
Iin  2  d  I o  2  d 
2
Fig.ure 3. Mode II operation
In Fig. 3 when the switch S is opened, the inductor current iL1
decreases with voltage (Vo - 2 Vin). Therefore, the ripple of
the inductor current iL1
2
(11)
The variation ratio of inductor current iL1 is
73
INTERNATIONAL CONFERENCE ON RENEWABLE AND SUSTAINABLE ENERGY (ICRSE-13)
Jose. J. and Jayanand B., Vol. 2, Special Issue, pp. 72-76, 2014
1 
iL1 / 2 d (2  d )TVin d (1  d ) 2 R


I L1
2 L1 I in
2(2  d ) fL1
(12)
The ripple voltage of output voltage Vo is
Vo 
Q I o (1  d )T 1  d Vo


C2
C2
fC 2 R
(13)
Therefore, the variation ratio of output voltage Vo is
Vo / 2
1 d
 

Vo
2 fRC 2
(14)
The static and dynamic performance of PI control for the
positive output elementary super lift Luo converter is
evaluated in Matlab/Simulink. The Matlab/Simulink
simulation model is depicted in Fig.4. It can be seen that
error in output voltage of the power switch (n – MOSFET) of
PI control input is obtained by the difference between
feedback output voltage and feedback reference output
voltage, and output of PI control, change in duty cycle of the
power switch ( n - channel MOSFET).
III. PI CONTROL OF POSITIVE OUTPUT ELEMENTARY SUPERLIFT
LUO CONVERTERS
For the purpose of optimize the stability of positive output
elementary super lift Luo converter dynamics, while ensuring
correct operation in any working condition, a PI control is a
more feasible approach. The PI control has been presented
as a good alternative to the control of switching power
converters. The main advantage PI control schemes is its
insusceptibility to plant/system parameter variations that
leads to invariant dynamics and static response in the ideal
case. The PI control is designed to ensure the specifying
desired nominal operating point for POESLLC, then regulating
POESLLC, so that it stays very closer to the nominal operating
point in the case of sudden disturbances, set point variations,
noise, modeling errors and components variations.
The PI regulator is:
U ( s)
K
 KP  I
E ( s)
s
(15)
IV.
Figure 4. Simulation model of PI control of positive output elementary
luo converter
SIMULATION
V.
Simulations have been performed on the positive output
elementary super lift Luo converter circuit with parameters
as in the table 1.
SIMULATION RESULTS
Output volage vs time
40
35
Parameter’s name
Symbol
Value
Input voltage
Vin
12 V
Output voltage
Vo
36 V
Inductor
L1
100µH
Capacitors
C1,C2
30µF
Nominal
switching
frequency
Load resistance
Fs
100KHz
R
100
Duty cycle
d
0.5
output voltage(volt)
30
Table 1. Circuit parameters
25
20
15
10
5
0
0
0.1
0.2
0.3
0.4
0.5
time(sec)
0.6
0.7
0.8
0.9
1
Figure 5. Output voltage of positive output superlift luo converter
when input is 12 V
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INTERNATIONAL CONFERENCE ON RENEWABLE AND SUSTAINABLE ENERGY (ICRSE-13)
Jose. J. and Jayanand B., Vol. 2, Special Issue, pp. 72-76, 2014
50
45
40
output voltage(v)
35
30
25
20
15
10
5
0
0
0.1
0.2
0.3
0.4
0.5
time(s)
0.6
0.7
0.8
0.9
1
Figure 6. Output voltage of positive output superlift luo converter when
input takes a step change from 12 V to 15 V
Figure 9. Input voltage=12 V
40
35
output voltage(v)
30
25
20
15
10
5
0
0
0.1
0.2
0.3
0.4
0.5
time(s)
0.6
0.7
0.8
0.9
1
Figure 7. Output voltage of positive output superlift luo converter when
input takes a step change from 12 V to 9 V
VI. HARDWARE IMPLEMENTATION
Figure 10.Pulse from the real time card
The hardware implementation of positive output elementary
superlift luo converter was done.IRF540n was used as the
switch. The PWM signal from the data acquisition card PCI1711L is not capable of driving MOSFET. In order to
strengthen the triggering pulses, IR2111 driver is used.. Input
to the converter was 12 V. For d = 0.5 , an output voltage of
36 V is obtained.
Figure 11. Output of IR2111
Figure 8. Experimental set up
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INTERNATIONAL CONFERENCE ON RENEWABLE AND SUSTAINABLE ENERGY (ICRSE-13)
Jose. J. and Jayanand B., Vol. 2, Special Issue, pp. 72-76, 2014
Figure 12. Output voltage = 36 V, for d = 0.5
VII.
[3] F.L.Luo and H.Ye, “Positive outputsuper lift converters,” IEEE
Transaction on power electronics,Vol.18, No. 1, pp. 105-113,
January 2003.
[4]Luo, F. L.: ‘Re-Lift Converter: Design, Test, Simulation and
Stability Analysis’, IEE Proceedings on EPA, Vol. 45, No. 4, July
2003, pp. 315-325.
[5]F.L.Luo and H.Ye, “Negative outputsuper lift converters,” IEEE
Transaction on power electronics,Vol.18, No. 5, pp. 1113-1121,
September 2003
[6]F. L. Luo, H. Ye, and M. H. Rashid, “Four-quadrant operating Luo
converters,” in Proc. IEEE Int. PESC’00 Conf., Galway, Ireland, June
18–23, 2000, pp. 1047–1052.
[7]Power Electronics Handbook by M.H.Rashid
[8]Power Electronics by Umanand (Inductor design)
CONCLUSION
A series of dc/dc converters—positive output super-lift
converters has been successfully created. It largely increases
the voltage transfer gain in power-law. Very high output
voltage is easily obtained. Simulation and experimental
results verified the design and calculations. The effect of the
parasitic elements of DC-DC converters limits their output
voltage and power transfer efficiency .This work introduced
the advanced voltage lift techniques to be successfully
applied in the DC-DC converter design and feedback with PI
controller. They overcome the effect of parasitic elements
and greatly increase the output voltage of the DC-DC
converters, introducing the characteristic of high efficiency,
high power density, cheap topology in simple structure and
near-zero output voltage and current ripples. These establish
the validity of the proposed PI controller that effectively
rejects changes in DC supply voltage and load resistance
which achieving fast tracking of the converter output voltage.
ACKNOWLEDGMENT
The authors would like to thank the head of the
department of Electrical Engineering, Government College of
Engineering, Idukki, Kerala for providing the facilities to
conduct Research in Power Electronics lab. The research was
conducted during 2012-2013.
REFERENCES
[1] A.Joseph basanth,S.P. Natarajan,T.S. Sivakumaran, “Simulation
and DSP Based Implementation of Conventional Controller for
rd
Double Output Elementary LUO Converter”, 2009 IEEE 3
International Conference on Power Electronics Systems and
Applications
[2]F.L.Luo, “Double output Luo converters, advanced voltage lift
technique,” Proc. Inst. Elect. Eng., vol. 147, no. 6, pp. 469–485,
Nov. 2005.
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