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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 3, Issue 11, November 2014
Cascaded Hybrid Seven Level Inverter with
Different Modulation Techniques for
Asynchronous Motor
Ankur Chourasiya, Poonam Chouksey, Nayna Bhargava, S. P. Phulambrikar
Abstract- This paper presents a asymmetric cascaded hybrid
7 level multilevel inverter using different switching techniques
i.e. phase disposition pulse width modulation, degree
modulated pulse generator and hybrid mixed switching
technique. This paper presents comparison between motor
output and THD of Asymmetrical Cascaded hybrid 7 level
Multilevel Inverter (MLI) using different modulation
techniques. These control schemes is applied to 7 level
Asymmetrical Cascaded hybrid Multilevel Inverter
(CHMLI). Different topologies of multilevel inverter have
been reported in the literature, but this work mainly
focuses on the asymmetrical cascaded hybrid multilevel
inverter circuit with reduced number of switches and input
DC sources. THD and motor output are analyzed in FFT
window. The results are observed by MATLAB/SIMULINK
software.
keywords- Asymmetrical CHMLI, Mixed switching, Degree
modulated pulse generator , PDPWM.
1. INTRODUCTION
Inverter is a device that converts electrical power from DC
to AC form using electronic circuits. Generally simple
inverter gives 2 or 3 level output voltage .The inverters with
number of voltage level equal to three or above that are
known as multilevel inverter.MLI are capable of producing
high power high voltage as the unequal voltage sources of
of MLI allows to reach high voltage wiyh low harmonics
without the use of transformer.MLI is a latest alternative to
implement low frequency based inverter with low output
voltage distortion.Basic Multilevel topologies are of 3 types
shown in below:

Diode clamped inverter

Flying capacitor inverter

Cascaded
Figure 1.1 Multilevel inverter topologies
2. CASCADED H-BRIDGE MLI
Cascaded H-Bridge (CHB) configuration has recently
become very popular in high-power AC supplies and
adjustable-speed drive applications. A cascade multilevel
inverter consists of a series of H-bridge (single-phase full
bridge) inverter units in each of its three phases. Each Hbridge unit has its personal dc source, which for an
induction motor would be a battery unit, fuel cell or solar
cell. Each SDC (separate D.C. source) is associated with a
single-phase full-bridge inverter. The ac terminal voltage
of different level inverters is connected in series. Through
different combinations of the four switches, S1,S2,S3 &
S4, each converter level can generate three different
voltage outputs, +Vdc, -Vdc and zero. The AC outputs of
different full-bridge converters in the same phase are
connected in series such that the synthesized voltage
waveform is the sum of the individual converter outputs,
Note that the number of output-phase voltage levels is
defined in different way from those of the two previous
converters (i.e. flying capacitor and diode clamped). In
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ISSN: 2278 – 7798
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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 3, Issue 11, November 2014
these topologies the number of output-phase voltage
levels is defined by m= 2N+1, where N is the number of
DC sources
A seven-level cascaded converter, for example, consists
of three DC sources and three full bridge converters are
Minimum harmonic distortion can be obtained by
controlling the conducting angles at different converters
levels. Each H- bridge unit generates a quasi-square
waveform by phase shifting its positive and negative
phase legs‟ switching timings. Every switching devices
always conduct for 180° or half cycle regardless of the
pulse width of a quasi-square wave. These switching
methods make all of the switching devices current stress
equal. In the motoring mode a power flows from the
batteries through the cascade inverter to the motor.
Figure 2.4 shows the basic block of cascade H-bridge
Multi-level inverter and its associated switching instants.
As shown it consists of a DC source and. The switching
states for four power devices are constant i.e., When S1 is
on, S2 cannot be on and vice versa, similarly with S3 or
S4.
3.1 H-BRIDGE MLI USING HYBRID MIXED
SWITCHING SCHEME
seven level hybrid cascaded multilevel inverter with a
mixed pulse width modulation method is designed by
reducing a number of switches.
A simulation diagram using a mixed switching scheme of
Seven-level HMLI with asynchronous motor are shown
in a figure 3.1 using MATLAB/SIMULINK.
In the charging mode, the cascade
converters act as rectifiers, and power flows from the
charger (ac source) to the batteries. The cascade
converters can also act as rectifiers to help recover the
kinetic energy of the vehicle if regenerative braking is
used. The cascade inverter can also be used in parallel
HEV configurations. This new converter can avoid extra
clamping diodes or voltage balancing capacitors
.
The combination of the 180° conducting method and the
pattern-swapping scheme make the cascade inverter’s
voltage and current stresses the same and battery voltage
balanced.
Figure-3.1 Seven-level HMLI using hybrid mixed
switching scheme simulation diagram with asynchronous
motor
Figure 2.1 Block of a h-bridge Multi-level inverter
The simulation block diagram has seven level cascaded
hybrid multilevel inverter with asynchronous motor is
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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 3, Issue 11, November 2014
shown in Fig-3.1 These are combination two types
inverter: first one is H-bridge inverter and other is two
conventional inverter. The conventional inverter is acting
as the main inverter and H bridge inverter is acting as the
auxiliary inverter.
3.1.1 HYBRID MIXED SWITCHING SCHEME
Table:5.1. Pulse Generation Formula in seven level
HMLI.
multilevel inverter with unequal voltage sources are
utilize to generate same number of voltage level per
phase. The MLI consist of full bridge cell for maximum
voltage and half bridge cell for intermediate voltage.
When MLI fed an induction motor drive system, to
reduce harmonics losses and saving energy. In topology
we have generated 7 level voltage as 0V, 100V,200V and
300V.
A simulation diagram using degree modulated pulse
generator (DMPG) switching scheme of Seven-level
HMLI with asynchronous motor are shown in a figure
3.2 using MATLAB/SIMULINK.
These pulses are given for eight switches. Two
conventional inverter has a S1, S2, S3, S4 and H-bridge
inverter has four pulse Sa3, Sa4, Sa5, Sa6. By using these
modulation technique to have controlled seven level
output voltage Then seven level output voltage of Hybrid
multilevel inverter is produce in asynchronous motor
drives & parameters of the motor are analysis in a output
figure 4.2.
3.2. H-BRIDGE MLI USING DEGREE
MODULATED PULSE GENERATOR (DMPG)
Figure-3.2.1 Using degree modulated pulse generator
(DMPG) switching scheme of Seven-level HMLI with
asynchronous motor
SWITCHING SCHEME
In seven levels H bridge MLI total eight switches and two
batteries are uses to control the output voltage. IN
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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 3, Issue 11, November 2014
3.2.1
DEGREE
MODULATED
PULSE
GENERATOR (DMPG) SWITCHING SCHEME
Figure 3.3.1: Seven-level HMLI with asynchronous
motor using phase disposition (PD) PWM switching
scheme
Figure 3.2.2: Simulink model for Gate driver circuit of 7
levels HMLI
3.2.1
PHASE
DISPOSITION
SWITCHING SCHEME
(PD)
PWM
The switching technique here used is degree modulated
pulse generated to identification and reference angle
generation. We have generated a switching pulse to obtain
staircase output voltage which resembles nearly equal to
sine wave. For different switching angles the power
circuit behaves defiantly producing different waveform.
To obtain equal step firing a 7 level output is divided into
equal segment.
3.3 H-BRIDGE MLI USING PHASE DISPOSITION
(PD) PWM SWITCHING SCHEME.
The simulation circuit for asymmetric cascaded 7 level
with induction motor is shown in fig 3.3.1 CHMLI 7 level
has two unequal magnitude DC sources and 8 power
switches are used.
A simulation diagram using phase disposition (PD) PWM
switching scheme of Seven-level HMLI
with
asynchronous motor are shown in a figure 3.3 using
MATLAB/SIMULINK.
Figure 3.3.2 Reference and carrier waveform for PD
Seven-level HMLI
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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 3, Issue 11, November 2014
4. SIMULATION RESULTS
Output voltage wave forms in Seven Level HMLI
400
300
Magnitude in Voltage(V)
200
100
0
-100
-200
-300
-400
0
0.01
0.02
0.03
0.04
0.05
TIME (Seconds)
0.06
0.07
0.08
0.09
0.1
Figure-4.1 Output voltage waveform for Seven-level
HMLI using hybrid mixed switching scheme
Show the above figure-4.1 MATLAB simulation result
for a seven level inverter with hybrid mixed switching
scheme. Multilevel carrier based pulse width modulation
methods are used in these inverter topologies.
Fig 4.3: Motor output of seven-level HMLI using hybrid
mixed switching scheme
Output voltage of Seven-level HMLI using degree modulated pulse generator (DMPG) switching scheme
300
200
Fundamental (50Hz) = 265.7 , THD= 10.59%
VOLTAGE AMPLITUDE
Mag (% of Fundamental)
6
5
4
100
0
-100
3
-200
2
-300
1
0
0
0.02
0.04
0.06
0.08
0.1
TIME(SEC)
0
2
4
6
8
10
12
14
16
18
20
Harmonic order
Figure 4.4: Output voltage of Seven-level HMLI using
degree modulated pulse generator (DMPG) switching
scheme
Figure-4.2 FFT analysis for Seven-level HMLI using
hybrid mixed switching scheme
Show the above figure MATLAB simulation result for a
seven level inverter with equal step firing using degree
modulation switching scheme
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100
International Journal of Science, Engineering and Technology Research (IJSETR), Volume 3, Issue 11, November 2014
0
-100
-200
0
0.01
0.02
0.03
0.04
Time (s)
0.05
0.06
0.07
0.08
Output voltage waveform for Seven-level HMLI using degree modulated pulse generator (DMPG) switching scheme
Fundamental (50Hz) = 257.5 , THD= 26.22%
400
300
VOLTAGE AMPLITUDE
Mag (% of Fundamental)
20
15
10
5
0
0
100
200
300
400
500
Frequency (Hz)
600
700
800
900
200
100
0
-100
-200
-300
1000
-400
Figure-4.5 FFT analysis for Seven-level HMLI using
degree modulated pulse generator (DMPG) switching
scheme
0
0.01
0.02
0.03
0.04
0.05
TIME (SEC)
0.06
0.07
0.08
0.09
0.1
Selected signal: 4 cycles. FFT window (in red): 4 cycles
Figure-4.7 Output voltage waveform for Seven-level
200
HMLI using phase disposition (PD) PWM switching
100
scheme
0
-100
output
The
voltage waveform of 7 level CHMLI with
-200
capacitor
start run motor induction motor is shown in fig
4.7 0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
Time (s)
Fundamental (50Hz) = 288.2 , THD= 4.65%
Mag (% of Fundamental)
2.5
2
1.5
1
0.5
0
Figure-4.6: Motor output of seven-level HMLI using
degree modulated pulse generator (DMPG) switching
scheme
0
100
200
300
400
500
Frequency (Hz)
600
700
800
900
1000
Figure-4.8 FFT analysis for Seven-level HMLI using
phase disposition (PD) PWM switching scheme
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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 3, Issue 11, November 2014
Table no. 4: Variation of Induction Motor Parameters
HMLI
using
switching
scheme
Main
winding
current
(Amp)
Rotor speed (
rad /sec)
Electromagnetic
Torque (Nm)
mixed
switching
6.5
151
3.8
degree
modulated
9.2
151
6.8
phase
disposition
6.7
157
4.7
All simulation results are shown in above table no. 3 and
table no. 4 respectively.
5. CONCLUSION
Figure-4.9: Motor output of seven-level HMLI using
phase disposition (PD) PWM switching scheme
Table no. 3: Steady state value for Induction Motor
HMLI
Time to
using
reached
switching Steady
scheme state value
of Main
winding
current
Time to
Time to
reached reached Steady
Steady
state value of
state
Electromagneti
value of
c Torque
Rotor
Speed
mixed
switching
0.25 sec
0.25 sec
0.25sec
11.53 %
degree
modulate
d
0.2 sec.
0.25 sec
0.2 sec
22.89%
6. REFERENCES
phase
dispositio
n
0.2 sec.
9.76%
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0.2 sec.
0.2 sec.
THD
The paper deals with a comparison of cascaded 7 level
multilevel inverters for Asynchronous motor using
different modulation techniques i.e. phase disposition
pulse width modulation, degree modulated pulse
generator and hybrid mixed switching technique. Indeed,
asymmetrical 7 level multilevel inverter have been
compared in order to find an optimum motor speed,
torque and main winding current with lower switching
losses, Total harmonic distortion and optimized output
voltage quality. The asymmetric cascaded 7 level inverter
gives optimum motor output and reduced THD using
pulse width modulation technique. The steady state
condition of motor output has reached earlier in case of
asymmetrical cascaded 7 level inverter using pulse width
modulation (phase disposition) as compared to other
two techniques.
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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 3, Issue 11, November 2014
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Ankur chourasiya - received the B.E.degree in
Electronics and communication. From the
Peoples collage of research and technology,
Bhopal (M.P.) India, in 2008-2012 .and M.Tech
pursuing From Samrat ashok technical institute
Vidisha (m.p.) India, done M Tech thesis on
“Harmonic Reduced In New PWM Switching
Scheme of Hybrid Multilevel Inverter” paper publish on “Harmonic
Reduction in New PWM Switching Scheme of Hybrid Multilevel
Inverter” International Journal of Engineering Research & Technology
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Poonam Chouksey recrived the B.E. degree in
Electrical engineering From Indira Gandhi
Engineering collage Sager, M.P. India in 2008 to
2012.& Master of Engineering pursuing from samrat
ashok technological institute, vidisha, M.P. india.
done M.E. thesis topic on “Design of Efficient
Novel Multilevel Inverter By Reducing Harmonics
With Reduces Number of Batteries and Switches” and paper published
on “Design of Efficient Novel Multilevel Inverter By Reducing
Harmonics With Reduces Number of Batteries and Switches”
International Journal of Engineering Research & Technology (IJERT)
ISSN:2278-0181 Vol. 3,Issue 8,August-2014.
.
Nayna Bhargava received B.E. degree in Electrical
engineering from Lakshmi Narain College Of
Technology Bhopal , MP. India in 2006 to 2010 &
Master Of Engineering pursuing from Samrat Ashok
Technological Institute, Vidisha, M.P. India. done
M.E. thesis topic on “Analysis of Asymmetric
Cascaded 7 level and 9 level Multilevel Inverter for
Asynchronous Motor” and paper published on
“Analysis of Asymmetric Cascaded 7 level and 9 level Multilevel
Inverter for Asynchronous Motor” International Journal of Engineering
Research & Technology (IJERT) ISSN:2278-0181 Vol. 3,Issue
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electrical engineering department of Samrat ashok
technological institute Vidisha (m.p.)
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