A non isolated soft switching DC–DC converter and load at full range of zero-voltage switching (ZVS) characteristic is proposed. The proposed converter consists of an auxiliary circuit, an inductor, two switches, and 2 diodes to achieving high efficiency at full range of load. At low and heavy loads, ZVS of switching device is achieved by energy storing component. The inductor energy stored varies with load and hence results in minimizes conduction loss. This leads to switching of device for full range of load. The proposed DC - DC converter achieves high efficiency as switching loss is reduced due to soft switching and ZVS operation which severe to reduce conduction loss. The efficiency is improved about 4% in boost mode (2.5% in buck mode) at full range of load. To verify the performance of the proposed converter, experimental results prototype are presented.

1. http://www.iaeme.com/IJEET/index.asp 62 editor@iaeme.com
International Journal of Electrical Engineering & Technology (IJEET)
Volume 7, Issue 5, September–October, 2016, pp.62–69, Article ID: IJEET_07_05_006
Available online at
http://www.iaeme.com/IJEET/issues.asp?JType=IJEET&VType=7&IType=5
ISSN Print: 0976-6545 and ISSN Online: 0976-6553
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© IAEME Publication
NON-ISOLATED SOFT SWITCHING DC-DC
CONVERTER AND LOAD AT FULL RANGE OF ZVS
Kirti G. More and Ramling D. Patane
Department of Electonics, Terna Engineering College, Navi Mumbai, India.
ABSTRACT
A non isolated soft switching DC–DC converter and load at full range of zero-voltage
switching (ZVS) characteristic is proposed. The proposed converter consists of an auxiliary circuit,
an inductor, two switches, and 2 diodes to achieving high efficiency at full range of load. At low
and heavy loads, ZVS of switching device is achieved by energy storing component. The inductor
energy stored varies with load and hence results in minimizes conduction loss. This leads to
switching of device for full range of load. The proposed DC - DC converter achieves high
efficiency as switching loss is reduced due to soft switching and ZVS operation which severe to
reduce conduction loss. The efficiency is improved about 4% in boost mode (2.5% in buck mode) at
full range of load. To verify the performance of the proposed converter, experimental results
prototype are presented.
Key words: High efficiency, Non-isolated dc–dc converter, Switching loss, zero-voltage switching
(ZVS).
Cite this Article: Kirti G. More and Ramling D. Patane, Non-Isolated Soft Switching DC-DC
Converter and Load at Full Range of ZVS. International Journal of Electrical Engineering &
Technology, 7(5), 2016, pp. 62–69.
http://www.iaeme.com/IJEET/issues.asp?JType=IJEET&VType=7&IType=5
1. INTRODUCTION
RENEWABLE energy sources like sunlight, wind, tides, waves, and geothermal heat are replacing fossil
fuels which produce CO2. The electrical energy generated by the renewable sources varies in accordance
with climatic conditions. For example, a solar power generation system depends on location and weather
condition. A wind power generation system depends on speed and direction of wind. Hence for renewable
power system an additional storage system along with DC-DC converter and unified batteries is used to
maintain constant supply of power in commercial and industrial applications [1]-[6].The DC-DC
converters are of two types, Isolated and Non-Isolated, depending on their application. The converters in
which breaking of ground loop is done with an isolated transformer and require more than four switches
are the isolated DC-DC converters [2]. While the non isolated converter consists of simple circuitry having
inductors and two switches which provides high efficiency than isolated type of converter [3].The non-
isolated DC-DC converters are divided into five types. Buck, boost, buck-boost, cuk and full bridge
converter. These non isolated converters with application of soft switching method are used to achieve

2. Non-Isolated Soft Switching DC-DC Converter and Load at Full Range of ZVS
http://www.iaeme.com/IJEET/index.asp 63 editor@iaeme.com
high efficiency at full range of load. Hence reduce conduction and switching losses of switches in power
system [7].
Figure 1 Conventional DC DC Converter
Figure 1 shows soft switching dc-dc converter using resonant network formed by series inductor. The
zero voltage switching (ZVS) characteristics is achieved at full range of load by large value of circulating
current flowing through series inductor. The circulating current is free of conduction losses and load. The
efficiency of converter can get degraded due to large conduction loss during light loads. Soft switching
converter circuitry was proposed which provides soft switching characteristics and ripple free current by
inductor [6]. But the conduction losses are of high value due to large amount of circulating current.
To eliminate this problem, a high-efficiency DC DC converter with low current and ZVS characteristic
at full range of loads is proposed, in Fig. 2. The varying ON time of switches controls the energy stored in
inductor L. During light loads ZVS of switch Q2 is achieved by the inactive inductor L and hence has
minimized conduction loss. This results in providing high efficiency at full range of loads. A theoretical
analysis and experimental prototype of the proposed converter are presented to verify the performance of
the proposed converter.
2. THE PROPOSED CONVERTER
Figure 2 Proposed DC-DC Converter
Figure 2 shows the circuit diagram of the proposed DC–DC converter consisting of non isolated or
transformer less topology. The converter has dc input source, inductor L, diode D, filter capacitor C,
controlled switch Q and load as R. When the switch is ON inductor current increases and diode is in OFF
state. As the switch is off the energy stored in inductor is transferred to output. Hence no energy is
supplied by input during this period. Diode D1 and D2 are the freewheeling diodes.
Figure 3 shows theoretical waveforms for proposed converter in boost and buck modes, respectively
[8].

3. Kirti G More and Ramling D Patane
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Figure 3 Buck-Boost Converter Waveform during switch ON and OFF
2.1. Buck Mode
A buck converter provides a lower output voltage than the input voltage. The main application is in dc
regulated power supplies .The basic buck with a purely resistive load is represented infig.4. Consider a
circuit with ideal switch with constant instantaneous input voltage and purely resistive load and then the
instantaneous output voltage waveform is represented in Fig.4 [8]. The output voltage is calculated in
terms of the switch duty ratio:
= + 0 = = (1)
Substitute D in Eq. (1)
where = =
= ! " # = $% ! " #
Where $ = &
= '()* +)
The output voltage can be controlled by varying the duty ratio ! ,⁄ of the switch which results in
linear variation of output voltage VO with control voltage. The fluctuations in output voltage are decreased
by low pass filter made up by an inductor and a capacitor.
When the switch is ON, the diode is reverse biased and input serves energy to inductor and load. Hence
during OFF state of switch the inductor current flows through diode and transfer some of its stored energy
to load. Thus the inductor current is equal to output current.
(a) (b)
Figure 4 Buck converter

4. Non-Isolated Soft Switching DC
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2.1.1. Buck Converter as Continuous Conduction Mod
Figure 5 shows buck converter operating in continuous conduction mode[8]. Here inductor current flows
continuously ./0 1 02 .During t
providing positive voltage across inductor
to /0.The stored inductive energy
(a)
Figure 5 Buck converter state (a) switch
The waveform repeats from one time period to next in steady state operation. Hence the integral of
inductor voltage 0 is zero at one time period, since
or
Hence for given input voltage the duty ratio of switch varies linearly with output voltage and the
voltage across inductor is zero.
or
Assuming associated power loss of circuit elements to be low, then
Since
Isolated Soft Switching DC-DC Converter and Load at Full Range of ZVS
EET/index.asp 65
Buck Converter as Continuous Conduction Mode (CCM)
5 shows buck converter operating in continuous conduction mode[8]. Here inductor current flows
.During ton ,switch is on and inductor current flows and reverse bias diode
providing positive voltage across inductor , 0 = 3 . Hence inductor current
.The stored inductive energy /0 flows through diode during OFF state of switch and
(a) (b)
Buck converter state (a) switch ON; (b) switch OFF switching states
The waveform repeats from one time period to next in steady state operation. Hence the integral of
ero at one time period, since , = ! + 44
5 0 = 5 0 + 5 0
6
= 0
3 ! = , 3 !
7
&
= = 8 9 :+ /(
Hence for given input voltage the duty ratio of switch varies linearly with output voltage and the
! + 0. 44
,
=
=
!
,
=
Assuming associated power loss of circuit elements to be low, then < = <
= = =
And
>
>&
= &
=
?
DC Converter and Load at Full Range of ZVS
editor@iaeme.com
5 shows buck converter operating in continuous conduction mode[8]. Here inductor current flows
switch is on and inductor current flows and reverse bias diode
Hence inductor current increases linearly
flows through diode during OFF state of switch and 0 = 3 .
OFF switching states
The waveform repeats from one time period to next in steady state operation. Hence the integral of
(2)
Hence for given input voltage the duty ratio of switch varies linearly with output voltage and the
3

5. Kirti G More and Ramling D Patane
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Hence by controlling the duty ratio of switch, buck converter in continuous conduction mode works
equivalent to dc transformer.
2.2. Boost Mode
As shown in figure 6, for this type of DC-DC Converter the output voltage is always higher than the input
voltage [8]. The diode is reverse biased as the switch is in ON state. This causes isolation of output stage
and inductor receives energy from input. During OFF state of switch output receives energy from input and
inductor.
Figure 6 Boost Converter
2.2.1. Boost Converter as Continuous Conduction Mode (CCM)
Figure 7 represents waveform for continuous conduction current when inductor current flows
continuously./0 1 02.82 . For one time period the time integral of inductor voltage is zero.
! + 3 44 = 0
Figure 7 Continuous conduction mode: (a) switch ON (b) switch OFF

6. Non-Isolated Soft Switching DC-DC Converter and Load at Full Range of ZVS
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Dividing both sides by , and rearranging
&
=
BB
= C?
4
Assuming a lossless circuit, < = < ,
∴ = = =
And
>
>&
= 1 3 5
3. EXPERIMENTAL RESULTS
The theoretical analyses of proposed converter are verified by prototype with the given design
specifications: VJK = 9V , VMN = 35V, L = 85mH as experimentally found. The switching device IRF640N
for switches are used in proposed converter prototype. An ATMEL microcontroller 89C8051 is used. To
achieve stable efficiency ADC MCP3201 along with feedback network formed by operational amplifier is
used.
3.1. Verification of Boost Mode
Figure 8 shows the experimental waveforms for switch in ON and OFF period for boost mode. The
conduction losses and switching losses are minimized as compared to the conventional soft switching dc–
dc converter as shown in Fig. 1.Hence total efficiency is improved.
3.2. Verification of Buck Mode
Figure 8 shows the experimental waveforms for switch in ON and OFF period for buck mode. ZVS
operation of the switches is achieved in a full range of loads.
Figure 8 Observed Waveform

7. Kirti G More and Ramling D Patane
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3.3. Measured Efficiency
Figure 9 shows the measured efficiency for the conventional dc–dc converter and the proposed converter
in boost and buck modes. The efficiency of converter in Fig. 1 is measured with the parameters L= 85mH
and C = μF. The proposed converter achieves high efficiency and ZVS of switches for full range of
loads.The proposed converter provides the efficiencies of 95.68% in boost mode and 94.02% in buck mode
are obtained. Fig.10 shows the photograph of proposed dc–dc converter.
Figure.9 Measured Efficiency versus Power (a) Buck Converter; (b) Boost Converter
Figure 10 Proposed prototype of DC DC Converter
4. CONCLUSION
In this paper, high-efficiency with non isolation soft switching and load at full range of ZVS is proposed.
The measured efficiency of the proposed converter is more than 94% from 10% load to full load. At full
load as compared with a conventional hard-switching dc–dc converter, the improved efficiency is 4% in
boost mode (2.5% in buck mode).This is because of reduced switching loss by means of ZVS operation of
the switches and the minimized conduction loss The maximum efficiencies of 95.68% in boost mode and
94.02% in buck mode are measured in the proposed converter. The proposed dc–dc converter is
appropriate for a system between a 9-12 V batteries.
84
86
88
90
92
94
96
50 100 150 200
Proposed
Converter
Soft Switching
Converter
Conventional
Hard Switching
Converter
84
86
88
90
92
94
96
98
50 100 150 200
Proposed
Converter
Soft Switching
Converter
Conventional
Hard Switching
Converter

8. Non-Isolated Soft Switching DC-DC Converter and Load at Full Range of ZVS
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