International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT) - 2016
Three Level DC-DC Boost Converter For
High Conversion Ratio
Ashwini S Musale
Prof. Bapusaheb T Deshmukh
Electronics Engineering
Jawaharlal Nehru Engineering College
Aurangabad, India
ashwini.musale2@gmail.com
Electrical, Electronics and Power Engineering
Jawaharlal Nehru Engineering College
Aurangabad, India
bapu_desh@rediffmail.com
Abstract— This paper present three level DC-DC boost converter
topology for high conversion ratio. This topology is a combination
of traditional boost topology with voltage multiplier. The
Traditional boost converter is unable to provide high gain ratio
since it has high voltage stress and high duty cycle, hence the
three level DC-DC boost converter is used which gives the reliable
high conversion ratio. The main advantage of proposed topology
is output voltage can be increased by using the combination of
capacitors and diodes at output side of the converter, without
altering main circuit. Proposed circuit is used for high power
application with severe duty cycle. The proposed three level dc-dc
boost converter topology consists of 5 capacitors, 7 diodes, 2
inductors and a switch. The design parameters of proposed
topology are input voltage, output voltage and duty cycle which
are of the ratings 28V, 167V and 46% respectively. The
verification of proposed topology is done by experimental results.
in the input side to distribute the input current and voltage
multiplier cell is adopted in the output side to achieve a high
step up gain[11]. The great strides taken in the industrial
applications of power electronics during recent years have
demonstrated that this versatile tool can be of great
importance in increasing production, efficiency & control. A
converter uses a matrix of power semi conductor switches to
converter electrical power at a high efficiency. Conventional
DC-DC boost converter is not suitable for high voltage gain
application because of high voltage stress and high duty
cycle [8][9].In voltage-mode and current-mode control have
been widely utilized for the control of switching dc–dc
converters, which enjoy various benefits, such as small
ripple, small steady-state error, and constant switching
frequency. In[12]secondary rectification which helps to
extend the converter voltage gain and reduce the turns ratio
of transformer. When PWM generated topology is used in
converters where as efficient bi-directional digital
communication used switch mode power converters [13]. A
boost converter using a power MOSFET has output of boost
always greater than the input voltage. The DC-DC multilevel
boost converter is proposed for not only for electrical drives
application but also for inverter. The main advantage of
proposed Switched inductor multilevel boost converter is
high gain efficient with high duty cycle as compared to
convectional multilevel boost converter. This topology is a
modification of recently proposed boost multilevel converter.
In this paper include three section I shows introduction of
different topology are used for conversion of high gain
application, Where as section-II implementation of
traditional boost converter with added levels of capacitors
and operation of modes, depends on switch (on and off).
Section-III, It shows analysis of proposed topology and
comparison with recent topology.
Keywords—Boost converter; Votage multiplier; DC-DC converter;
Switched inductors, floating output.
I. INTRODUCTION
Electricity being the basic need of day to day life, hence to
fulfill the huge requirement of electricity it is better to use
renewable energy sources (solar energy, wind energy,
biomass energy, geothermal energy, etc).The output of
renewable energy source such as Fuel cell, solar energy,
wind energy, etc is having low voltage gain hence it is
required to boost the output voltage for higher gain[1]. For
example the output of solar system is only 12-24V DC but
this voltage is not sufficient to use it for other applications,
hence DC-DC multilevel boost converter is used for having
higher voltage gain [2][3][4].Mostly renewable energy
sources are used in grid or smart grid system, these energy
sources standby with battery or without battery backup. This
type of grid applications are used for high gain step-up dc-dc
converters [6][7]. Power Electronics is the art of converting
and controlling of electrical energy from one form to another
form in an efficient and clean manner for convenient
utilization [5]. In [10] operation of this topology is depend on
continuous and discontinuous inductor current mode for
reduced switching stress. In interleaved structure is employed
978-1-4673-9939-5/16/$31.00 ©2016 IEEE
II. PROPOSED CONVERTER AND OPERATING MODE
A. Block Diagram
Multilevel DC-DC converter combines the function of
conventional DC-DC converters and voltage multiplier as
shown in Fig1. The gain of multilevel converter is depends
upon the duty cycle of gate pulse and number of levels
present in voltage multiplier. This proposed converter used
for many application such as inverter, electrical drives, which
required high output voltage more than input.
Fig.3 Charged inductor L1, L2 through diode D6, D8
Fig.1Block diagram of multilevel DC-DC boost
converter
B. Multilevel Boost Converter
The proposed topology of three level boost converter gives
high gain floating output. Boost converter 5-capacitors, 7diodes, 2-inductor and 1-switch are required to design the
circuit.
As shown in above Fig.2 switch S, inductor L, diode D1 and
C1 form the conventional boost converter stage. The output
from the capacitor C1 is considered as first level output of
multilevel DC-DC boost converter and is denoted as Vc1.
The output from the capacitor C3, C5 is considered as
second and third level output of multilevel DC-DC boost
converter respectively.
•
When the inductors are charged, at the same time
voltage across capacitor C1, charges the capacitor C2
through a diode D2, because D2 is forward biased.
Fig.4 Charging of capacitor C2 through diode D2
• Input supply Vin and output side capacitors C1, C3
charges the capacitor C2 and C4 through Diode D4 is
forward biased.
Fig.2 Proposed topology of three level DC-DC boost converter
C. Modes of Operation
The operation of multilevel DC-DC boost converter (MBC)
can be divided into two modes, one when switch S is ON and
another when switch S is OFF.
Mode 1(Switch is ON)
•
•
When switch S is turned ON, the inductor L1 and L2
charged parallel by input voltage Vin through diode
D6 and D8.
Diode operate only one direction and first condition
is unspecified capacitors are fully charged C1,C3,
C5.
Fig.5 Charging of capacitor C2, C4 through diode D4
Mode 2 (Switch is OFF)
• When switch s is OFF, at that time Inductors L1 and
L2 discharged in series therefore diode D6 and D8
are reversed biased and diode D7 and D1 are
forward biased, capacitor C1 is charged by inductor
L1 and L2 through diode D7 and D1.
has finite internal resistance. Due to this internal resistance
forward voltage drop takes place. Voltage drop across diode
and switch is Vd.
According to analysis, three level switched inductor dc-dc
boost converter, ratio is
Fig.6 Charging of capacitor C1 and discharge L1, L2
Again diode D7 & D3are forward biased the voltage
across the inductors L1, L2 and capacitor C2
charges the Capacitor C1 and C3. When discharged
capacitors C1, C3, C5 charges by using input side
capacitors C2, C4.
•
Vout 2 + 4 D
=
Vin
1− D
(1)
Vout
1
=
Vin 1 − D
(2)
When compare the proposed topology with recent topology
is as followed
• Simple boost converter
•
•
•
Multilevel boost converter
Vout
3
=
Vin 1 − D
(3)
Vout 1 + D
=
Vin 1 − D
(4)
Vout N (1 + D)
=
Vin
(1 − D)
(5)
Switched inductor boost converter
Switched inductor multilevel boost converter
The above comparable points are draw the charts of gain
verses duty cycle.
Fig.7 Charging of capacitor C1, C3 through diode D3
•
Inductors L1 and L2 and Capacitor C1 and C4 are
charged by capacitor C1, C3 and C5 through Diode
D7 and D5.When D7 and D5 are forward biased.
Fig. 9 Voltage gain compare with output levels
Fig.8 Charging of capacitor C1, C3, C5 through diode D5
III. ANALYSIS OF PROPOSED BOOST CONVERTER
In practical boost converter circuits, the switch and diodes
The proposed topology is compared with the other
researched topology, Fig 9 shows calculated values of duty
cycle verses voltage gain in graphical manner. It means
proposed topology shows three levels of multiplier circuit
only changes the value of duty cycle, see the value of voltage
gain. Fig 10shows the increased number level and see the
effect of voltage gain. In proposed equation, first calculate
the voltage gain for N=1, N=2, N=3 with changing duty
cycle.
Fig.13 Pulse width across switch
Fig. 10 Voltage gain compare with different topology
IV. EXPERIMENTAL RESULTS
The proposed switched inductors DC-DC multilevel boost
converter has been designed for three levels, input voltage is
28.1V, output voltage 167V.1.5mH inductors, 220µf
capacitors, duty cycle 46%, switching frequency 50kHz used
for designed the proposed converter.
Fig.14 Input and Output voltage waveform
V. CONCLUSION
Fig.11Hardware module of proposed converter
The above hardware module input side connect main supply
to step down transformer 230/30V, bridge rectifier.
The output of bridge rectifier is gives to boost circuit, control
circuit, switched inductor and multilevel circuit serially links
are done. After the attached components through probes
DSO shows the results.
A switched inductor boost converter is presented in this
paper which has very large dc-dc conversion ratio at high
duty cycle. The main advantage of proposed topology is
output voltage level can be increased by adding capacitors
and diodes at output side of the converter, without disturbing
main circuit. This topology shows 74% competent than the
other topology.
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Fig.12 Top view of hardware model
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