International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
PV Based Resonant Two Inductor Boost Converter for
Induction Machine Drive Application
1
Praveen Sebastian, 2Jomole Joseph
Mar Baselios College of Engineering, Electrical and Electronics Engineering
2
Assisstant Professor, Electrical and Electronics Engineering, Mar Baselios College of Engineering
Kerala university
1
Abstract— A new converter is designed to drive an
induction motor directly from PV energy. The
developed system is based on a current-fed multi
resonant converter for achieve zero current
switching. It is also known as resonant two-inductor
boost converter (TIBC) and a three-phase voltage
source inverter. The classic topology of the TIBC has
features like high voltage gain and low input current
ripple. The topology is further improved with the use
of a non isolated recovery snubber. The converter
output is fed to a three phase ac motor via a three
phase inverter.
condition for the input switches and output rectifying
diodes and this enables the converter to operate at
high frequency with greater efficiency.
This paper introduce a new DC-DC converter for
photovoltaic water pumping systems. The
arrangement will be in the form section II gives
detailed description about solar system III gives
detailed description about proposed system, detailed
working of converter is presented in section IV
control part in section V; simulation results in section
VI
II.SOLAR SYSTEM
Keywords— photovoltaic
converter, AC motor drives
I.
power
system,
tibc
INTRODUCTION
In conventional PV based drive systems boost
converter and low voltage DC machine is used. Input
current ripple in the boost converter fed drive system
is higher and DC motor have lower efficiency and
higher maintenance cost compared with Induction
machine. To avoid these problems two inductor boost
converter fed induction machine drive system was
introduced. Input current ripple is less but power
regulation range is reduced[2]. The two inductor
boost converter exhibits benefits in high power
applications and high input current is split between
two inductors, thus reducing power loss in both
copper windings and primary switches. Maintain
power regulation range in the TIBC converter fed
induction machine drive system an auxiliary
transformer is introduced. But they still have
problems with high voltage spikes created due to
leakage inductance of the transformer and high
voltage stress on the rectifying diodes[1]. The
solution to the current fed PWM converter is use of
resonant topologies able to utilize the component
parasitic characteristics such as the leakage
inductance and winding capacitance of transformers
in a productive way to achieve the zero current
switching(ZCS) or zero voltage switching(CVS)
condition. Modified resonant two inductor boost
converter is introduced for PV based drive system
due to its very small no of components, simplicity,
high efficiency, easy transformer flux balance and
common ground gating driving for both switches[3].
Input current is distributed through the two boost
inductors having its current ripple amplitude halved
at twice the PWM frequency. TIBC can be modified
to multiresonant converter to achieve zero current
ISSN: 2231-5381
A solar cell is the building block of a solar
panel. A photovoltaic module is formed by
connecting many solar cells in series and parallel.
Considering only a single solar cell; it can be
modeled by utilizing a current source, a diode and
two resistors[4]. This model is known as single diode
model of solar cell. Two diode models are also
available but only single diode model is considered
here
Fig 1: Single diode model of a solar cell
The characteristic equation for a photovoltaic cell is
given by
Iph= Iscr+ Ki (T-298)*ƛ ⁄1000
Where,
Irs=Iscr⁄([exp(qVoc/(Ns kAT))-1])
Io
I rs [
T 3
Ego
1
] exp[ q *
]{
Tr
Bk
Tr
Ipv=Np*Ipv-Np*Io[exp〖{(q*(Vpv+IpvRs
1
}]
T
))/(Ns
AkT)}-1]〗
I & V : Cell output voltage and current
Ios : Cell reverse saturation current
T : Cell temperature in celsius
-19
k : Boltzmann's constant, 1.38 * 10
http://www.ijettjournal.org
J/K;
Page 254
International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
-23
q : Electron charge, 1.6*10 C;
Ki : Short circuit current temperature coefficient at
Iscr;
Iscr : Short circuit current at 25 degree Celsius;
Ilg : Light-generated current;
Ego : Band gap for silicon;
A : Ideality factor;
Tr :Reference temperature;
Ior : Cell saturation current Tr;
Rsh : Shunt resistance;
Rs : Series resistance;
The characteristic equation of a solar module is
dependent on the number of cells in parallel and
number of cells in series[4]. It is observed from
experimental results that the current variation is less
dependent on the shunt resistance and is more
dependent on the series resistance.
PV module models are implemented as
masked subsystems in Simulink. Inputs are PV
current and insolation and outputs are PV voltage and
PV power. Matlab M-file program written inside
matlab function to obtain PV current as output with
voltage, irradiation and temperature as inputs.
Filter capacitors are electrolytic so it will affects the
life time of the converter
Current fed converters have some
advantages they are it have high step-up voltage ratio
and reduces transformer turns ratio but its
disadvantages are high voltage stress due to leakage
inductance of transformers and high high voltage
stress on rectifying diodes. This disadvantages can be
overcome by the use of resonant topology. There for
the converter will modified as resonant converter.
The component parasitic parameter like the leakage
inductance and winding capacitance of transformer in
a fruit full way to achieve zero current
switching(ZCS) or zero voltage switching(ZVS)[6].
Table 1.Electrical characteristics data of solar 1.3 KW PV
module
Rated Power
1.3KW
Voltage at maximum power
87V
Current at maximum power
15.04A
Open circuit voltage
88.2V
Short circuit current
29.95 A
Total no of cells in series
10
Total no cells in parallel
8
Cell voltage(series)
8.82V
Cell voltage(parallel)
3.74V
Fig:2 simplified block diagram of water pumping system
III. PROPOSED CONVERTER
Proposed converter is designed for higher
efficiency application. Its advantages are high life
time, low cost and easy accessibility. This converter
design focused on single stage PV module. Fig.2
shows the basic block diagram of the system.
The energy from PV panel fed to induction
motor by two simple power stages. The TIBC
converter used here for boost the voltage from the PV
panel and Three phase inverter convert the DC
voltage from the converter to 3phase AC voltage.
The two inductor boost converter requires
large voltage conversion ratio because of low input
current ripple and low voltage nature of photovoltaic
panels. The commonly use voltage fed converter have
high input current ripple so filter capacitor needed[5].
ISSN: 2231-5381
Fig.3 shows the modified tibc topology. The main
parts are
resonant tank circuit, voltage doubler
rectifier and snubber circuit. Resonant tank circuit is
for achieving zero current switching or zero voltage
switching. By employing a voltage double rectifier at
the secondary terminal of the transformer as in
fig.3(b), it is possible to reduce voltage stress on the
MOSFETs to half of the orginal ones, transformer
turns ratio as well as necessary ferrite core can be
reduced. Finally as a result the transformers and
MOSFETs can be made cheaper and the no of diodes
in the secondary sides can be halved. Classically, the
TIBC have a minimum operation load to maintain an
established output voltage. Below a certain load level,
the energy transferred to the output capacitor is not
completely transferred to the load and causes an
increase in the output voltage[9]. This happens
because the inductors are charged even if there is no
output current. As a result, this converter has a
drawback when used in motor drive systems. Since
the motor is a variable load and it has large time
constants, it will demand low power at some
operation points. As a solution non dissipative
regenerative snubber circuit is presented shown in fig
3(c)..
http://www.ijettjournal.org
Page 255
International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
Fig.3 Modified TIBC topology: (a) resonant tank (b)
voltage doubler rectifier (c) snubber
IV. OPERATION PRINCIPLE
Two Inductor boost converter have six operating
modes. The theoretical wave forms of these operating
modes are illustrated in fig.4. At time t1, the
rectifying diode Do1 is already conducting, and the
voltage on resonant capacitor Cr is clamped at +Vout/2.
At this instant, the switch Q1 is activated by VgQ1.
As the switch is turned ON, its voltage drops to zero,
and the snubber diode Ds1 is forced to stop
conducting. From t1 to t2, Cr transfers its energy to
the leakage inductance Lr, beginning the primary
switch’s resonant process and forcing the current IQ2
on the switch Q2 to decrease.
decrease until it reverses its polarity. When IQ2 is
negative, the switch can be turned off. This happens
at instant t3 when VgQ2 is forced to zero. At the time
t3, the voltage VdsQ2 starts to increase, Q2 is
completely blocked, and the snubber diode Ds2
begins to conduct, transferring energy directly to the
snubber capacitor Cs. Between t3 and t4, Cr and Lm
continue to resonate, decreasing the voltage on the
doubler rectifier’s input and on VCr. At instant t4, the
voltage across Cr reaches −Vout/2, and the rectifying
diode Do2 starts to conduct, clamping VCr in
−Vout/2. From t4 to t5, the capacitor Co1 is
charged, and the current Of Do2 starts to decrease.
At the instant t5, Q2 is turned on, initiating the
resonant process on Q1. As Q2 is activated, Ds2 is
forced to stop conduction. At the instant t6, the
current in Do2 reaches zero, and Do2 stops
conducting, reinitiating the resonance between Cr and
Lm. From this moment, until the end of the switching
period, the process repeats symmetrically as
explained for the other input switch. A simplified
methodology based on the effect of each resonant
process, the resonant frequencies, and the switching
frequency is applied. Matlab simulations and a
prototype is used to show that, despite the simplicity
of the design methodology, the correct operation of
the converter is guaranteed, particularly the soft
switching of the primary switches for the whole
operating load range. Although the resonant process
affects the output voltage, depending on the resonant
tank component values and the load, this can be
neglected because of its small influence and complex
effect.
Although the resonant process affects the
output voltage, depending on the resonant tank
component values and the load, this can be neglected
because of its small influence and complex effect.
Thus, neglecting the resonant effect over the output
voltage, including the voltage doubler rectifier and
the snubber connecting the primary and the secondary
side of the converter[1].
V.SYSTEM DESIGN
The static voltage gain (Kv) of the converter
is defined as
Vout
Vin
Fig.4 key wave forms of the tibc during switching
period
From t2 to t3, the primary switch’s
resonance (Q2) continues to force its current to
ISSN: 2231-5381
Kv
1
1
D
(2
Ns
Np
1)
where D represents the duty cycle of each
switch and must be higher than 50% to guarantee the
necessary overlapping for the correct operation.
Ns/Np represents the transformer turns ratio. To
minimize the influence of the load on the resonant
process on the primary current commutation interval,
the switching frequency (Fsw) should be higher than
http://www.ijettjournal.org
Page 256
International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
the resonant frequency (Frs) of Lm and Cr by a value
of at least 1.1. Thus,
Frs
1
LmCr
2
RESONANT TANK CIRCUIT DESIGN
Fsw
1.1
1
Lm Lr
Cr
Lm Lr
(D
2
2
Lm 5.8 10
Fsw 1.1
80 103 /1.1
1
Lm
Frp
2
72727.27
9
456958.9314
9
1
5.8 10 9 Lm
0.5)
2.08811465
Fsw
2
8.25 10
1
Lr Cr
4
9
0.000825
Fsw
(2 D 1)
Lr 5.8 10
1
Lr 5.8 10 9
9
Lr 5.8 10
40 103
40 103
251327.4123
1
2
TON
10
1211.106497
1
The whole resonant process of the primary
switches has the duration of half a resonant cycle, as
shown in Fig. 4. To guarantee the ZCS condition for
the entire load range, the following conditions must
be satisfied:
9
40 103
1
6.31 1010
9
(5.8 10 Lr )
1
360.359
Lr
r
Frp
LmCr
1
LmCr
1
Lm
The duration of the commutation interval is
equal to the overlapping time (Tov) of the pulse
driving signals and can be calculated as
TON
2
5.8 10
1
Lr Cr
2
Lm Cr
1
Considering that Lm represents the
magnetizing inductance and Lr
represents the
leakage inductance, then Lm is much larger than Lr;
thus, can be simplified to
Frp
2
1
During the primary current commutation
interval, when both switches Q1 and Q2 are turned
on, inductor Lr participates on the resonance in
parallel with Lm and Cr; thus, the resonant frequency
for this interval is defined as
Frp
1
Frs
FSW
2D 1
Another important constraint is the energy
accumulated in Cr at the beginning of the primary
switching resonant process. This energy needs to be
completely transferred to the leakage inductance Lr
during this process. From this condition, the
following equation is derived:
Lr
2.729 10
3
2
Lr
V0
2
VO
Cr
2 I 2 in
ISSN: 2231-5381
http://www.ijettjournal.org
Page 257
International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
The bus voltage which is defined using the
minimum necessary voltage for the inverter topology
and PWM strategy. Two inductor boost converter
switching frequency must be compromised between
the switching losses and the inductor as well as
transformer size. Switching frequency is usually
designed to be 80 KHZ, which is used in simulation.
During fixed duty cycle control in order to guarantee
overlapping conduction of MOSFETs, D is chosen to
be 53% based on the
minimum required overlapping and commutation
times of the MOSFT and the drivers selected
VI.SIMULATION RESULTS
The simulink model of PV based two
inductor boost converter connected to induction
motor is shown below
Fig 5. Simulink model of PV based TIBC connected
to induction motor
Fig 6 shows the gate voltages of two
switches. During fixed duty cycle control in order to
guarantee the overlapping conduction of MOSFETs,
D is chosen to be 53% based on the minimum
required overlapping and commutation times of the
MOSFET and the drivers selected.
Fig.6 Gate voltage waveforms
ISSN: 2231-5381
Table.2 Converter parameters
Parameters
Values
Inductance Li1,Li2,Li3
100µH
Capacitance C01,C02,C03
1.5µF
Cr
5.8nF
Lr
2.729mH
Lm
0.825mH
Switching frequency
80kHZ
The output of two inductor boost converter
settles at 415V. The simulation result of output of the
converter is shown below. Simulation result of input
of the DC to DC converter.
Fig 7 shows the output voltage of the DCDC converter.
Fig.7 output of the DC to DC converter
Fig 8 shows the simulation result of zero
current switching. From the simulation result it is
clear that both turn on and turn off occurs at zero
current switching.
Fig.8 Verification of zero current condition on the input
switch Q2
http://www.ijettjournal.org
Page 258
International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
As can be seen, for an input DC voltage of
415V, the circuit produces 3phase ac voltage output
(fig .9).The output voltages of three phases are 120
degree apart from one another. Thus inverter action
was obtained. The filtered output voltage waveforms
of inverter are shown below in fig 10.
Fig 9 Output line voltage waveforms for 3 phase PWM
inverter with machine load
Fig.10 Filtered output voltage of inverter
Table.3 Machine parameters
PARAMETERS
VALUES
Rr
3.805
Rs
4.85
Lls
0.0062
Llr
0.0062
Lm
0.25
fb
50
p
4
J
0.03
Lr
Llr+Lm
Tr
Lr/Rr
wb
2*pi*fb
Xls
wb*Lls
Xlr
wb*Llr
Xm
wb*Lm
Xmstar
1/(1/Xls+1/Xm+1/Xlr).
Fig.12 shows three phase current,torque and speed of
the machine. The machine accelerates and come to
steady state at 0.5 sec with a small slip because of
inertia load. The machine is simulated by applying
415V three phase ac voltage at 50 Hz
With just inertia (TL=0).
Fig.11 complete dq model of induction
machine
The inputs of a Induction machine are the
three-phase voltages, their fundamental frequency
and the load torque. On the other hand the outputs are
the three-phase currents, the electrical torque and the
rotor speed. The machine parameters of 2Hp
induction machine is used for simulation.
ISSN: 2231-5381
Fig.12 Three phase currents ,torque and speed of induction
machine
When TL= 10 Nm, at steady state Te approaches TL,
rotor speed reduces due to loading with ὡe =313
rad/sec and ὡr = 299rad/sec shown in Fig.13
http://www.ijettjournal.org
Page 259
International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
Fig.13 The stator current of the induction motor at rated
speed
VII.CONCLUSION
Software model of PV based two inductor boost
converter fed induction machine drive is done and
concluded that the DC output obtained was very high
in PV based TIBC fed induction machine drive
compare with conventional topology. Switching
losses are eliminated by achieving zero current
switching(ZCC).
[13] R.-Y. Chen, T.-J.Liang, J.-F.Chen, R.-L.Lin, and K.-C. Tseng,
―Study and implementation of a current-fed full-bridge boost dc-dc
converter
withzero-current
switching
for
high-voltage
applications,‖ IEEE Trans. Ind.Appl., vol. 44, no. 4, pp. 1218–
1226, Jul./Aug. 2008.
[14J. Kim, H.-S.Song, and K. Nam, ―Asymmetric duty control of a
dualhalf- bridge dc/dc converter for sing] le-phase distributed
generators,‖ IEEETrans. Power Electron., vol. 26, no. 3, pp. 973–
982, Mar. 2011.
[15] B. Liu, C. Liang, and S. Duan, ―Design considerations and
topology selection for dc-module-based building integrated
photovoltaic system,‖ in Proc. 3rd IEEE Conf. ICIEA, Jun. 3–5,
2008, pp. 1066–1070.
[16] J. Biela and J. W. Kolar, ―Using transformer parasitics for
resonant converters—A review of the calculation of the stray
capacitance of transformers,‖ in Conf. Rec. 40th IEEE IAS Annu.
Meeting, 2005, pp. 1868–1875.
[17] L. Yan and B. Lehman, ―Isolated two-inductor boost converter
with one magnetic core,‖ in Proc. IEEE Appl. Power Electron.
Conf. Expo., 2003,pp. 879–885.
[18] Y. Jang, ―Two-boost converter,‖ U.S. Patent 6 239 584, May
29, 2001.
[19] Q. Li and P. Wolfs, ―The power loss optimization of a current
fed ZVS two-inductor boost converter with a resonant transition
gate drive,‖ IEEETrans. Power Electronics, vol. 21, pp. 1253–
1263, Sep. 2006.
[20] B. Ozpineci and L. Tolbert, ―Simulink implementation of
Induction machine model,‖ IEEETrans. Power Electronics,vol.14,
pp. 623-632, feb.2013
REFERENCES
[1]J. victor, G. Farias, L.Teizeira, L. Ribeiro, ―Implementation of
high efficiency, High-life time, and low cost converter For an
autonomous photovoltaic water pumping system,” IEEE Trans.
Ind. Applications, vol. 50, no.1,pp. 631-637,feb. 2014
[2] United state patents –Jang et. Al. patent no US 6,239,584B1
[3] D. Tschanz, H. Lovatt, A. Vezzini, and V. Perrenoud, ―Single
phase three level boost power factor correction converter,‖ in Proc.
IEEEAPEC, Proc, pp. 434–439,1995
[4] N. Pandirajan, R. RanganathMuthu ―Mathematical modelling
of photovoltaic module with simulink,‖ICEES,pp.3-5,jan 2011
[5] M. A. Vitorino, M. B. R. Correa, C. B. Jacobina, and A. M. N.
Lima, ―An effective induction motor control for photovoltaic
pumping,‖ IEEE Trans.Ind. Electron., vol. 58, no. 4, pp. 1162–
1170, Apr. 2011.
[6] S. R. Bowes and A. Midoun, ―Suboptimal switching strategies
for microprocessor controlled PWM inverter drives,‖ Proc. Inst.
Elect. Eng.—Elect.Power Appl., vol. 132, no. 3, pp. 133–148, May
1985.
[7] M. Cacciato, A. Consoli, and V. Crisafulli, ―A high voltage
gain dc/dc converter for energy harvesting in single module
photovoltaic applications,‖ in Proc. IEEE ISIE, 2010, pp. 550–555.
[8] P. J. Wolfs, ―A current-sourced dc-dc converter derived via the
duality principle from the half-bridge converter,‖ IEEE Trans. Ind.
Electron., vol. 40, no. 1, pp. 139–144, Feb. 1993.
[9] P. Wolfs and Q. Li, ―An analysis of a resonant half bridge dual
converter operating in continuous and discontinuous modes,‖ in
Proc. IEEE PowerElectron. Spec. Conf., 2002, pp. 1313–1318.
[10] W. Li, L. Fan, Y. Zhao, X. He, D. Xu, and B. Wu, ―High stepup and high efficiency fuel cell power generation system with
active clamp flybackforward converter,‖ IEEE Trans. Ind.
Electron., vol. 59, no. 1, pp. 599–610, Jan. 2012.
[11] T.-J. Liang, R.-Y.Chen, J.-F.Chen, and W.-J. Tzeng, ―Bucktype currentfed push-pull converter with ZCS for high voltage
applications,‖ in Proc.IEEE Region 10 Conf., 2007, pp. 1–4.
[12] P. M. Barbosa and I. Barbi, ―A new current-fed, isolated
PWM dc-dc converter,‖ IEEE Trans. Power Electron., vol. 11, no.
3, pp. 431–438, May 1996.
ISSN: 2231-5381
http://www.ijettjournal.org
Page 260