2013 International Conference on Renewable Energy and Sustainable Energy [ICRESE’13]
Simulation and Implementation of Superlift Luo
converter
Ms.Josily Jose
Dept of Electrical & Electronics
Govt.Engg College,Idukki
Kerala,India
jose.josily@gmail.com
Jayanand.B
Dept of Electrical & Electronics
Govt.Engg College,Idukki
Kerala,India
jayanandb@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 sub circuits
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-up converter) 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
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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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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
Δ i L1 =
Vin
V − 2 Vin
dT = o
dT
L1
L1
Vo =
2−d
Vin
1− d
(1)
(2)
The voltage transfer gain is
G =
Fig.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
=
V in
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 = i L 1− off = iC 1− off
(4)
iin −on = iL1−on + iCi −on
(5)
dTi C 1 − on = (1 − d )Ti C 1 − off
(6)
If inductance L1 is large enough, iL1 is nearly equal to its
average current iL1. Therefore
Fig.2. Mode I operation
iin − off = iC 1− off = I L1
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.
I
1− d
I L1 = L1
d
d
(8)
1− d
I L1
d
(9)
iin−on = I L1 +
iC1−on =
(7)
and average input current
Iin = diin−on + (1− d)iin−off = IL1 + (1− d)IL1 = (2 − d)IL1
Considering T = 1/ f and
Fig.3. Mode II operation
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(10)
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2
2
Vin ⎛ 1− d ⎞ Vo ⎛ 1− d ⎞
=⎜
=⎜
⎟
⎟R
Iin ⎝ 2 − d ⎠ Io ⎝ 2 − d ⎠
(11)
The variation ratio of inductor current iL1 is
ξ1 =
ΔiL1 / 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
Δ Vo =
Δ Q I o (1 − d )T 1 − d Vo
=
=
C2
C2
fC 2 R
(13)
Therefore, the variation ratio of output voltage Vo is
ε =
Δ Vo / 2
1− d
=
Vo
2 f RC
2
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
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).
(14)
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.
Fig.4 Simulation model of PI control of positive output elementary
luo converter
The PI regulator is:
V. SIMULATION RESULTS
U (s)
K
= KP + I
E (s)
s
(15)
Output volage vs time
40
35
SIMULATION
30
Simulations has been performed on the positive output
elementary super lift Luo converter circuit with parameters as
in the table 1.
o u t p u t v o lta g e (v o lt)
IV.
25
20
15
10
TABLE I. CIRCUIT PARAMETERS
5
0
Parameter’s
name
Input voltage
Symbol
Value
Vin
12 V
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0
0.1
0.2
0.3
0.4
0.5
time(sec)
0.6
0.7
0.8
0.9
1
Fig.5. Output voltage of positive output superlift luo converter
when input is 12 V
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50
45
40
o u t p u t v o lt a g e (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
Fig.6. Output voltage of positive output superlift luo converter
when input takes a step change from 12 V to 15 V
Fig.9. Input voltage=12 V
40
35
30
o u t p u t v o lt a g e (v )
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
Fig.7. Output voltage of positive output superlift luo converter when
input takes a step change from 12 V to 9 V
VI. HARDWARE IMPLEMENTATION
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 PCI-1711L 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.
Fig.10.Pulse from the real time card
Fig.11. Output of IR2111
Fig.8. Experimental set up
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[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.
Fig.12. Output voltage = 36 V, for d = 0.5
[7] Power Electronics Handbook by M.H.Rashid
VII.
[8] Power Electronics by Umanand (Inductor design)
CONCLUSION
A series of dc/dc converters—positive output superlift 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
Double Output Elementary LUO Converter”, 2009 IEEE 3rd
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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