Imperial Journal of Interdisciplinary Research (IJIR)
Vol-3, Issue-3, 2017
ISSN: 2454-1362, http://www.onlinejournal.in
A Review on Cascaded H-bridge
Multilevel Inverter in Electric Vehicle
Kajal Shah1, Himadri Raj2, Karnika bhonsale3 & Gaurang Mehta4
1,2,3
4
Student, Electrical Engineering Department, Babaria Institute of technology,
Assistant Prof., Electrical Engineering Department, Babaria Institute of technology,
Varnama, Gujarat, India.
Abstract: For motor driving applications, large
numbers of battery cells are used which are
connected in series to boost up the output voltage in
Electrical vehicle (EV) energy storage systems. Here
H bridge inverter topology is used to control battery
cell. All the H bridges are cascaded to output the
staircase type dc voltage. After that, an H-bridge
inverter will be used which will change the direction
of the dc bus voltages to make up the ac voltages.
The outputs of the inverter will be the multilevel
voltages with lesser harmonics and low dv/dt which
in turn will be helpful in improving the performance
of motor drives. By separately controlling each cell,
the energy utilization ratio will be improved. Also,
the imbalance in terminal voltage will be avoided so
that the life of batter stack can be improved. SPWM
switching scheme will be used to do modulation
control and to produce a five-level phase voltage.
The model will be developed using Matlab and
switching losses will be calculated along with total
harmonic distortion calculation. After the successful
completion of software based model, the hardware
prototype will be implemented to verify the
performance of the proposed inverter.
1. Introduction
In EVs , Two level inverter(TLI) is the far most
used power electronic converter today. It uses six
power electronic switches to create the voltage
needed for an electrical machine. Due to the demand
of a high voltage level, IGBTs are often used. The
IGBTs have relatively high losses compared to
MOSFETs at this power level, so it would be
beneficial to be able to use the MOSFET technology
at a lower voltage level. One way to be able to use
MOSFETs is to divide the battery into smaller units
with lower voltage, and use one inverter for each
battery module. The outputs of the inverters are then
series connected to be able to create the voltage
magnitude that the electric machine requires. This
inverter type is called a cascaded multilevel inverter
(MLI) This converter topology is becoming popular
for power system applications such as FACTS and
HVDC. In the great majority of the electrical
vehicles out on the market today,the charger is a
Imperial Journal of Interdisciplinary Research (IJIR)
stand-alone component. It can be either an on-board
charger that is located in the vehicle, or it can be an
off-board charger located at different locations in the
infrastructure. It is advantageous if the propulsion
power electronics can be used also for charging; then
the separate power electronics in the on board
charger is not needed, and space needs as well as
cost can be reduced. This has been showed to work
with the TLI,however, the consequences when doing
the same with the MLI, is not yet evaluated for a
vehicle application. It is stated that the MLI has
almost no electromagnetic interference (EMI) and is
therefore a safer and more accessible choice to have
in a vehicle. One other benefit is for example if one
battery cell in the battery pack has a lower capacity
compared to the rest of the cells, the whole battery
pack does not need to be used at the capacity level of
this weakest single cell. In a TLI this is the case but
for the MLI only the cells within that battery group
would need to be used less. The efficiency is also
discussed in general terms but without any
quantification. The efficiency is only predicted to be
higher than the one for the TLI. Obviously the MLI
has advantages regarding EMI and battery utilisation,
however, traceable results of the benefits of using a
MLI in electrified vehicles from an energy point of
view, and to what extent, is missing.
2. Recent Research Articles
Ehsan Najafi and his co-workers studied Design
and Implementation of a New Multilevel Inverter
Figure 1. Three-phase RV multilevel topology.
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Imperial Journal of Interdisciplinary Research (IJIR)
Vol-3, Issue-3, 2017
ISSN: 2454-1362, http://www.onlinejournal.in
Topology.In this paper, the power semiconduc-tor
switches are combined to produce a high-frequency
wave-form in positive and negative polarities.
However, there is no need to utilize all the switches
for generating bipolar levels. This idea has been put
into practice by the new topology.
This topology is a hybrid multilevel topology
which sep-arates the output voltage into two parts.
One part is named level generation part and is
responsible for level generating in positive polarity.
This part requires high-frequency switches to
generate the required levels. The switches in this part
should have high-switching-frequency capability.
The other part is called polarity generation part
and is responsible for generating the polarity of the
output voltage, which is the low-frequency part
operating at line frequency.
The topology combines the two parts (high
frequency and low frequency) to generate the
multilevel voltage output. In order to generate a
complete multilevel output, the positive levels are
generated by the high-frequency part (level generation), and then, this part is fed to a full-bridge
inverter (polarity generation), which will generate
the required polarity for the output. This will
eliminate many of the semiconductor switches which
were responsible to generate the output voltage
levels in positive and negative polarities.
Zhong Du and his co-workers studied DC–AC
Cascaded H-Bridge Multilevel Boost Inverter With
No Inductors for Electric/Hybrid Electric Vehicle
Applications. For HEV and EV applications,
sometimes, only short period peak power is required.
The modulation control can store energy to the
capacitors by boosting the capacitor voltage to a
higher voltage, which could be higher than Vdc
when the vehicle is working in a low power mode.
When the vehicle is working in high power modes,
the capacitors will deliver much higher power than
the continuous power to the motor load combined
with the battery, fuel cell, or generator. This feature
will greatly improve the vehicle’s dynamic
(acceleration) performance.
In this experiment, to achieve the highest output
voltages for the cascaded multilevel boost inverter
without inductors and the traditional inverter, two
steps were involved. First, the load was connected to
the bottom traditional inverter to output its highest
voltage; second, the load was connected to the
cascaded H-bridge multilevel inverter with the same
dc power supply voltage. The proposed cascaded Hbridge multilevel boost inverter without inductors
uses a standard three-leg inverter (one leg for each
phase) and an H-bridge in series with each inverter
leg. A fundamental switching scheme is used for
modulation control, to output five-level phase
voltages. Experiments show that the proposed dc–ac
cascaded H-bridge multilevel boost inverter can
output a boosted ac voltage with the same dc power
supply, which has a wider modulation index range
than a traditional inverter. The application of this dc–
ac boost inverter on HEV and EV can result in the
elimination of the bulky inductor of present dc–dc
boost converters, thereby increasing the power
density.
Thomas and his co-workers studied The present
disclosure discloses a multilevel inverter configured
to output a 3-phase voltage to a motor by allowing a
plurality of unit power cells forming one phase to be
serially connected, the multilevel inverter, the
multilevel inverter including a plurality of current
sensors configured to detect an output current of the
plurality of unit power cells. The present disclosure
proposes an input power of each unit power cell of a
cascaded Hbridge inverter that is mutually insulated.
To this end, the present disclosure includes a phase
shift transformer configured to output a voltage of
predetermined phase by receiving an AC input power
having a fixed frequency, and a plurality of unit
power cells serially-connected configured to output a
voltage having a predetermined phase by receiving a
voltage provided by the phase shift transformer,
wherein the phase shift transformer is configured to
include the number of phase shifts corresponding to
the number of the plurality of unit power cells. The
present disclosure proposes an input power of each
unit power cell of a cascaded Hbridge inverter that is
mutually insulated. To this end, the present
disclosure includes a phase shift transformer
configured to output a voltage of predetermined
phase by receiving an AC input power having a fixed
frequency, and a plurality of unit power cells
serially-connected configured to output a voltage
having a predetermined phase by receiving a voltage
provided by the phase shift transformer, wherein the
phase shift transformer is configured to include the
Figure 2. Switching angle solutions for proposed
dc–ac cascaded H-bridge multilevel boost
inverter control.
Imperial Journal of Interdisciplinary Research (IJIR)
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Imperial Journal of Interdisciplinary Research (IJIR)
Vol-3, Issue-3, 2017
ISSN: 2454-1362, http://www.onlinejournal.in
number of phase shifts corresponding to the number
of the plurality of unit power cells.
A great benefit with the multilevel inverter is that
the switches in each Hbridge only switches zero or
Figure 3. Schematic of a seven-level inverter in
single phase.
four times the fundamental frequency compared to
the TLI where all switches switch at least 20 times
per fundamental period.This gives much lower
switch losses. Moreover, since each switch is
subjected to a lower voltage level, the losses are even
lower in spite of the larger number of switches in the
MLI. A multilevel inverter can be built up using
many different topologies.
3. Acknowledgements
The repletion and euphoria that accompany the
successful completion of the project would be
incomplete & adamant without the mention of the
people who made it possible. We are very thankful to
all that well-wisher who contributes in my project
work; who gives me strength, time, knowledge, faith,
and support and take me towards the completion of
this project work. First of all, I adorably thank you to
our Professors of Bits edu campus, for their
amiableness support and faith.Further I greatly thank
to Mr Guarang Mehta, Assistant professor, Electrical
Engineering Department, Bits edu campus, internal
guide for guiding me in all the stage of my project,
giving full support My deepest thanks to my family,
friends for giving me full support in all situations.
4. References
[1] K. Jang-Hwan, S.-K. Sul, and P. N. Enjeti, “A carrierbased PWM method with optimal switching sequence
for a multilevel four-leg voltage-source inverter,”
IEEE Trans. Ind. Appl., vol. 44, no. 4, pp. 1239–1248,
Jul./Aug. 2008.
Imperial Journal of Interdisciplinary Research (IJIR)
[2] S. Srikanthan and M. K. Mishra, “DC capacitor
voltage equalization in neutral clamped inverters for
DSTATCOM application,” IEEE Trans. Ind.
Electron., vol. 57, no. 8, pp. 2768–2775, Aug. 2010.
[3] L. M. Tolbert, F. Z. Peng, and T. G. Habetler,
“Multilevel converters for large electric drives,” IEEE
Trans. Ind. Appl., vol. 35, no. 1, pp. 36–44, Jan./Feb.
1999.
[4] T. L. Skvarenina, The Power Electronics Handbook.
Boca Raton, FL: CRC Press, 2002.
[5] X. Yun, Y. Zou, X. Liu, and Y. He, “A novel
composite cascade multilevel converter,” in Proc.
33rd IEEE IECON, 2007, pp. 1799–1804.
[6] R. H. Osman, “A medium-voltage drive utilizing
series-cell multilevel topology for outstanding power
quality,” in Conf. Rec. 34th IEEE IAS Annu. Meeting,
1999, vol. 4, pp. 2662–2669.
[7] E. Najafi and A. H. M. Yatim, “A novel current mode
controller for a static compensator utilizing Goertzel
algorithm to mitigate voltage sags,” Energy Convers.
Manage., vol. 52, no. 4, pp. 1999–2008, Apr. 2011.
[8] N. Seki and H. Uchino, “Converter configurations and
switching fre-quency for a GTO reactive power
compensator,” IEEE Trans. Ind. Appl., vol. 33, no. 4,
pp. 1011–1018, Jul./Aug. 1997.
[9] G. Shahgholiyan, E. Haghjou, and S. Abazari,
“Improving the mitigation of voltage flicker by usage
of fuzzy control in a distribution static synchro-nous
compensator (DSTATCOM),” Majlesi J. Elect. Eng.,
vol. 3, no. 2,
pp. 25–35, Jun. 2009.
[10] K. Nakata, K. Nakamura, S. Ito, and K. Jinbo, “A
three-level traction inverter with IGBTs for EMU,” in
Conf. Rec. IEEE IAS Annu. Meeting, 1994, vol. 1, pp.
667–672.
[11] A. Jidin, N. R. N. Idris, A. H. M. Yatim, T. Sutikno,
and M. E. Elbuluk, “An optimized switching strategy
for quick dynamic torque control in DTC-hysteresisbased induction machines,” IEEE Trans. Ind.
Electron., vol. 58, no. 8, pp. 3391–3400, Aug. 2011.
[12] K. Y. Lau, M. F. M. Yousof, S. N. M. Arshad, M.
Anwari, and A. H. M. Yatim, “Performance analysis
of hybrid photovoltaic/diesel energy system under
Malaysian conditions,” J. Energy, vol. 35, no. 8,
pp. 3245–3255, Aug. 2010.
[13] G. M. Martins, J. A. Pomilio, S. Buso, and G. Spiazzi,
“Three-phase low-frequency commutation inverter for
renewable energy systems,” IEEE Trans. Ind.
Electron., vol. 53, no. 5, pp. 1522–1528, Oct. 2006.
[14] S. Daher, J. Schmid, and F. L. M. Antunes,
“Multilevel inverter topologies for stand-alone PV
systems,” IEEE Trans. Ind. Electron., vol. 55, no. 7,
pp. 2703–2712, Jul. 2008.
[15] R. Teodorescu, F. Blaabjerg, J. K. Pedersen, E.
Cengelci, and
P. N. Enjeti, “Multilevel inverter by cascading
industrial VSI,” IEEE Trans. Ind. Electron., vol. 49,
no. 4, pp. 832–838, Aug. 2002.
[16] D. A. B. Zambra, C. Rech, and J. R. Pinheiro, “A
comparative analysis between the symmetric and the
hybrid asymmetric nine-level series con-nected Hbridge cells inverter,” in Proc. Eur. Conf. Power
Electron. Appl., 2007, pp. 1–10.
[17] G. S. Perantzakis, F. H. Xepapas, and S. N. Manias,
“A novel four-level voltage source inverter-influence
of switching strategies on the distrib-ution of power
Page 719
Imperial Journal of Interdisciplinary Research (IJIR)
Vol-3, Issue-3, 2017
ISSN: 2454-1362, http://www.onlinejournal.in
losses,” IEEE Trans. Power Electron., vol. 22, no. 1,
pp. 149–159, Jan. 2007.
[18] E. Babaei, “Optimal topologies for cascaded submultilevel converters,”
J. Power Electron., vol. 10, no. 3, pp. 251–261, May
2010.
[19] G. Mondal, K. Gopakumar, P. N. Tekwani, and E.
Levi, “A reduced-switch-count five-level inverter
with common-mode voltage elimination for an openend winding induction motor drive,” IEEE Trans. Ind.
Elec-tron., vol. 54, no. 4, pp. 2344–2351, Aug. 2007.
[20] E. Beser, B. Arifoglu, S. Camur, and E. K. Beser,
“Design and appli-cation of a single phase multilevel
inverter suitable for using as a volt-age harmonic
source,” J. Power Electron., vol. 10, no. 2, pp. 138–
145, Mar. 2010.
[21] P. N. Enjeti, P. D. Ziogas, and J. F. Lindsay,
“Programmed PWM tech-niques to eliminate
harmonics: A critical evaluation,” IEEE Trans. Ind.
Appl., vol. 26, no. 2, pp. 302–316, Mar./Apr. 1990.
[22] T. Kato, “Sequential homotopy-based computation of
multiple solu-tions for selected harmonic elimination
in PWM inverters,” IEEE Trans. Circuits Syst. I,
Fundam. Theory Appl., vol. 46, no. 5, pp. 586–593,
May 1999.
[23] Z. Du, L. M. Tolbert, and J. N. Chiasson, “Active
harmonic elimination for multilevel converters,” IEEE
Trans. Power Electron., vol. 21, no. 2, pp. 459–469,
Mar. 2006.
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