International Journal of Research and Engineering
Volume 3, Issue 1
A New Single Switch Resonant Power Converter For PV Application
Author: Raisa Hudson
PG Scholar, Dept. of EEE, Toc H Institute of Science & TechnologyArakkunnam P.O, Kerala, India
Toc H Institute of Science & TechnologyArakkunnam P.O, Kerala, India
raisahudson@gmail.com
Abstract—This paper develops a novel single-switch
resonant power converter for renewable energy generation
applications. This circuit topology integrates a resonant
converter with zero-voltage switching (ZVS) with an
energy-blocking diode with zero-current switching (ZCS).
Only one active power switch is used for power energy
conversion to reduce the cost of active power switches and
control circuits. The active power switch is controlled by
pulse width modulation at a fixed switching frequency and
a constant duty cycle. When the resonant converter is
operated at discontinuous conduction mode, the inductor
current through the resonant tank could achieve ZCS of
the energy-blocking diode. Accordingly, a high energy
conversion efficiency is ensured. Given appropriately
chosen circuit parameters, the active power switch can be
operated with ZVS, and a measured energy conversion
efficiency of the proposed topology of 97.3% can be
achieved. Using MATLAB/SIMULINK the proposed
converter topology is simulated
Keywords—Photovoltaic
(PV),
resonant
power
converter, zero-current switching (ZCS), zero-voltage
switching (ZVS).
I.INTRODUCTION
The most common source of energy that is used for our
daily needs is obtained from fossil fuels. Owing to increase in
consumption, fossil fuel sources may be exhausted in the near
future. As people are much concerned with the fossil fuel
exhaustion and the environmental problems caused by the
conventional power generation, renewable energy sources and
among them fuel cells, photovoltaic panels and windgenerators are now widely used ([1],[2]). So a time has come
where we have to completely depend on renewable energy
sources. They include wind turbines, photovoltaic (PV)
modules, and fuel cell systems. PV power generation systems
have been regarded as the most promising future sources of
energy because of their advantages, such as the absence of a
need for fuel and the associated cost saving, low maintenance,
and lack of noise. If the direct-current (dc) output of renewable
energy generation systems is directly connected to a battery
energy storage system (BESS), then the output voltage of the
dc output source of the renewable energy generation system
will be fixed to the voltage of the BESS, so the renewable
energy generation system cannot always operate optimally.
Hence, a dc/dc interface must be installed between the
renewable energy generation system and the BESS to ensure
that the renewable energy generation system always operates
at its optimum operating points.
Power electronics use switching circuits to transform
energy and control power flow. Power semiconductor switches
are the critical components of power electronic circuits. The
simplest method for controlling power semiconductor switches
is pulse width modulation (PWM)[3]-[8]. The PWM approach
is to control power flow by interrupting current or voltage by
switching with control of the duty cycles. Conventionally, the
voltage across or current through the semiconductor switch is
8
abruptly altered; this approach is called hard-switching PWM.
Because of its simplicity, relatively low current stress, and
ease of control, hard-switching PWM approaches have been
preferred in modern power electronics converters. Owing to
the rapid developments of new power device technologies, the
switching speed of power devices has increased greatly.
Therefore, PWM power converters can now operate at a much
higher switching frequency, reducing the size of passive
components,
reducing the
overall
cost
of
the
system.However,the converter switching loss also increases in
proportion to the frequency. The increases in dv/dt and di/dt
caused by the increased speed increase stress on the device and
system electromagnetic interference noise. These effects set an
upper limit on the frequencies at which conventional hardswitching PWM converters can operate.
Resonant converters are extensively utilized in the
application of renewable energy generation systems. The basic
requirements of resonant converters are their small size and
high efficiency. A high switching frequency is required to
achieve small size. However, the switching loss increases with
the switching frequency, reducing the efficiency of the
resonant converters. To solve this problem, some softswitching approaches must be used at high switching
frequencies. Zero voltage switching (ZVS) and zero- current
switching (ZCS) techniques are two commonly used softswitching methods. In these techniques, either voltage or
current is zero during the switching transition, substantially
reducing the switching loss and increasing their liability of
resonant converters in renewable energy generation systems.
Traditional ZCS converters operate with constant on-time
control. They must operate with a wide range of switching
frequencies when the ranges of the input source and load are
wide, making the filter circuit design difficult to optimize.
However, the traditional ZVS scheme eliminates capacitive
turn-on losses and decreases the turn off switching losses by
reducing the rate of increase in voltage, reducing the overlap
between the switch voltage and the switch current.
II.OPERATING PRINCIPLES
Figure 1 shows a basic circuit diagram of the novel singleswitch resonant converter for PV applications. It comprises a
choke inductor Lm, a metal oxide-semi-conductor field-effect
transistor(MOSFET)that operates as a power switch S,a shunt
capacitor C, a resonant inductor Ls, an energy-blocking diode
D, and a filter capacitor Co. The capacitor Co and the load
resistance R together form a first-order low-pass output filter,
which reduces the ripple voltage below a specified level. The
MOSFET is a favoured device because its body diode can be
used as an anti-parallel diode DE for a bidirectional power
switch. Notably, the shunt capacitance C includes the power
switch parasitic capacitance and any other stray capacitance
(such as the winding capacitance of the choke Lm). Careful
design of the circuit parameters guarantees that the power
switch S is switched by ZVS and the energy-blocking diode D
is switched by ZCS, optimizing the operation of the converter.
ISSN 2348-7852 (Print) | ISSN 2348-7860 (Online)
(This work is licensed under a Creative Commons Attribution 4.0 International License.)
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International Journal of Research and Engineering
Volume 3, Issue 1
Interval IV :Between ωt3 and ωt4:
At the beginning of Mode IV, the active power switch
S is switched off. The capacitor current iC becomes iLm. Then,
the capacitor voltage Vc rises from zero to a finite positive
value. For ZVS operation, S is switched off at zero voltage,
and
the
capacitor
voltage
Vc
increaseslinearlyfromzeroataratethatisproportionalto iLm. The
capacitor current iC flows through capacitor C tocharge C,
transferring the energy from the dc input source to capacitor C.
During this mode, the output power of load resistor R is
supplied by the output capacitor Co. This mode ends when the
energy-blocking diode D is forward biased (Vc>Vo). Then, the
circuit operation enters Mode V.
Figure.1 Novel Single Switch Resonant Power Converter
A. Steady State Operation of the Converter
The key waveforms for each mode of the proposed
converter are shown in Figure. 2. One switching cycle is
divided into six modes, which are described as follows.
Interval I:Between ωt0 and ωt1
Prior to Mode I, the active power switch S is off. The
resonant tank current iLs is positive and exceeds the dc input
current iLm. The power switch must be turned on only at zero
voltage. Otherwise, the energy stored in the capacitor C will be
dissipated in the active power switch S. To prevent this
situation, the antiparallel diode DE must conduct before the
power switch is turned on. Since the capacitor current iC is
negative, it flows through capacitor C. When the capacitor
voltage VC falls to zero, a turn-on signal is applied to the gate
of the active power switch S. Therefore, the active power
switch S turns on under ZCS and ZVS conditions. At the
beginning of this mode, the antiparallel diode DE conducts
because the difference between currents iLm - iLs is negative.
In this mode, the energy-blocking diode D is turned on
because the resonant tank current i Ls is positive. This mode
ends as soon as the antiparallel diode DE is reverse biased by a
positive current iLm - iLs.
Interval V: Betweenωt4 and andωt5:
InModeV,the active power switch S remains in the
OFF state. The inductor current iLs is positive,andtheenergyblockingdiodeD isturnedon,yielding a resonant stage between
inductor Ls and capacitor C. In this interval, the capacitor
current iC is still positive. Hence, the capacitor voltage VC
continues to increase to its peak value. Mode V ends when
capacitor current iC resonates to zero at ωt5, and operating
Mode VI then begins.
Interval VI:Between ωt5 and 2π:
InModeV,theactivepower switch S remains in the OFF
state. The inductor current iLs is positive,andtheenergyblockingdiodeD isturnedon,yielding a resonant stage between
inductor Ls and capacitor C. In this interval, the capacitor
current iC is still positive. Hence, the capacitor voltage vc
continues to increase to its peak value.
Mode V ends when capacitor current iC resonates to zero at
ωt5, and operating Mode VI then begins.
Interval II :Between ωt1 and ωt2:
In this period, the switch S remains in the ON state.
The line voltage is applied to the choke inductor Lm, and iLm
increases continuously. In this mode, the current iLm - iLs
naturally commutates from the antiparallel diode DE to the
activepower switch S. Accordingly, the voltage across the
capacitorC is clamped at zero. The resonant current iLs passes
through the energy-blocking diode D. The circuit operation
enters Mode III when the inductor current iLs falls to zero.
Interval III :Between ωt2 and ωt3:
In Mode III, the active powerswitchS remainsinthe
ONstate,andtheinputdccurrent iLm continuously increases.
The choke inductor current iLm flows through the active
power switch S. The inductor current iLs falls until it reaches
zero and is prevented from going negative by the energyblocking
diode
D.
Notably,
the
dc
input
sourceisneverconnecteddirectlytotheoutputloadinthenovel
single-switch converter. Energy is stored in the choke inductor
Lm whentheactivepowerswitchisturnedonandistransferred to
the output load when the active power switch is turned off.
This mode is exited at the time when the power switch S is
turned off.
9
Figure.2 Steady-state operating waveforms of the novel singleswitch resonant power converter.
INPUT PARAMETERS AND SPECIFICATIONS.
Parameter
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(This work is licensed under a Creative Commons Attribution 4.0 International License.)
Attributes
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International Journal of Research and Engineering
Input Voltage
15V
Duty ratio
0.35
Load resistance
10Ω
Switching frequency
70 KHz
Resonant frequency
86 KHz
Inductors
Lm
8mH
Ls
19µH
Co
220µF
C
0.18µF
Capacitor
Volume 3, Issue 1
III.SIMULATION RESULTS
The circuit was simulated in MATLAB/SIMULINK.
The open loop simulation of the single switch resonant power
converter is shown in Figure.3. To realize ZVS operation of
the active power switch and ZCS operation of the energyblocking diode of the converter, the switching frequency must
satisfy fs < fo. The low-pass filter is designed to be small,
light, and low-cost. Simulation result of output voltage
andcurrent is shown in Figure.4 and the MOSFET voltage and
current waveform is shown in figure5.
Figure5. Waveforms of switching pulse, MOSFET Voltage
and current
The following equation gives the efficiency of the novel
single-switch resonant power converter:
OUTPUT PARAMETERS
Figure.3.Open loop simulation diagram
Output Voltage
18V
Output Power
32.4 W
Input Current
2.2A
Output current
1.8A
Efficiency
97.3%
IV..CONCLUSION
Figure.4Open loop simulation results
10
In this work, a highly efficient single-switch resonant boost
converter with an energy-blocking diode was designed for use
in a solar energy generation system. The structure of the
proposed converter is simpler and cheaper than other resonant
power converters, which require numerous components. The
developed single-switch resonant power converter offers the
advantages of soft switching, reduced switching losses, and
increased energy conversion efficiency. The performance of
the proposed converter is analyzed with the help of simulation
results and the simulated efficiency of the converter is found to
be 97.3%. If the converter is connected to a PV energy
generation system with Constant Voltage MPPT control, the
system can be used as a battery charger without any feedback
controllers as the output voltage of the converter remains
constant.
ISSN 2348-7852 (Print) | ISSN 2348-7860 (Online)
(This work is licensed under a Creative Commons Attribution 4.0 International License.)
http://www.ijre.org
International Journal of Research and Engineering
Volume 3, Issue 1
REFERENCES
[1].
[2].
[3].
[4].
[5].
[6].
[7].
[8].
J. Parikh, K. Parikh, “Growing Pains: Meeting
India's Energy Needs in the Face of Limited Fossil
Fuels,” IEEE Power and Energy Magazine,
Vol.
10, No. 3, pp. 59-66, 2012.
J. I. Nishizawa, “A Method to Avoid Dangers
Caused by Fossil Fuels,” Proceedings of IEEE, Vol.
96, No. 10, pp. 1559-1561, October 2008. W. Jiang
and B. Fahimi, “Multiport power electronic interface
Concept, modeling and design”, IEEE Trans. Power
Electron., vol. 26, no. 7, pp.1890-1900, Jul. 2011.
]A. M. Rahimi and A. Emadi, “Discontinuousconduction mode DC/DC converters feeding
constant-power loads,” IEEE Trans. Ind. Electron.,
vol. 57, no. 4, pp. 1318–1329, Apr. 2010. [9] F. Liu,
J. Yan, and X. Rua, “Zero-voltage and zero-currentswitching PWM combined three-level DC/DC
converter,” IEEE Trans. Ind. Electron., vol. 57, no. 5,
pp. 1644–1654, May 2010.
]A. M. Rahimi and A. Emadi, “Discontinuousconduction mode DC/DC converters feeding
constant-power loads,” IEEE Trans. Ind. Electron.,
vol. 57, no. 4, pp. 1318–1329, Apr. 2010.
] F. Liu, J. Yan, and X. Rua, “Zero-voltage and zerocurrent-switching PWM combined three-level
DC/DC converter,” IEEE Trans. Ind. Electron., vol.
57, no. 5, pp. 1644–1654, May 2010.
A. M. Rahimi and A. Emadi, “Discontinuousconduction mode DC/DC converters feeding
constant-power loads,” IEEE Trans. Ind. Electron.,
vol. 57, no. 4, pp. 1318–1329, Apr. 2010.
F. Liu, J. Yan, and X. Rua, “Zero-voltage and zerocurrent-switching PWM combined three-level
DC/DC converter,” IEEE Trans. Ind. Electron., vol.
57, no. 5, pp. 1644–1654, May 2010.
W.Li,J.Xiao,Y.I.Zhao,andX.He,“PWM
pulse
phaseangle shift(PPAS) control scheme for combined
multiport DC/DC converters,” IEEE Trans. Power
Electron., vol. 27, no. 3, pp. 1479–1489, Mar. 2012.
.
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