International Journal of Engineering Trends and Technology ... · (neutral clamped) inverter,...
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 27
Design and Simulation of Single-Phase Three-Level,
Four-Level and Five-Level Inverter Fed Asynchronous
Motor Drive with Diode Clamped Topology
Gerald Diyike1, Aniekan 0ffiong
2, Daniel Nnadi C
3
1 Department of Mechanical Engineering, Michael Okpara University of Agriculture, Umudike, P.M.B 7267, Abia State, Nigeria 2 Department of Mechanical Engineering, University of Uyo, Uyo, P.M.B. 1017, Akwa Ibom State, Nigeria
3 Departments of Mechanical Engineering, Michael Okpara University of Agriculture, Umudike, P.M.B 7267, Abia State, Nigeria
ABSTRACT - This paper deals with study of single-phase three-level,
four-level and five-level inverter fed asynchronous motor drive. Both
three-level, four-level and five-level inverters are realized by diode
clamped inverter topology. The poor quality of voltage and current of
a convectional inverter fed asynchronous motor is due to presence of
harmonic contents and hence there is significant level of energy
losses. The multilevel inverter is used to reduce the harmonic
contents. The inverter with a large number of steps can generate a
high quality voltage waveform. The higher inverter levels can be
modulated by comparing a sinusoidal reference signal and multiple
triangular carrier signals by the means of pulse width modulation
technique. The simulation of single-phase three-level, four-level and
five-level inverter fed asynchronous motor model is done using
(The math Works, Natick, Massachusetts,
USA). The Fast Fourier Transform (FFT) spectrums of the outputs
are analyzed to study the reduction in the harmonic contents.
Keywords - Asynchronous Motor, Multi-level inverters, pulse width modulation, Total harmonic distortion.
I. INTRODUCTION
Adjustable speed drives are the vital and endless demand of the industries and researchers. Asynchronous motors are widely
used in the factories and industries to control the speed of
conveyor systems, blower speeds, machine tool speeds and
applications that require adjustable speed controls. Thus, single-
phase asynchronous motors are extensively used for smaller
loads, such as household appliances like fans, water pumps. In
many industrial applications, traditionally, DC motors, provide
excellent speed control for acceleration and deceleration with
effective and simple torque control. The supply of a DC motor
connects directly to the field of the motor allows for precise
voltage control, which is necessary with speed and torque control applications. DC motors perform better than AC motors
on the some traction equipment. They are also used for mobile
equipment like golf cart, quarry and mining equipment. DC
motors are conveniently portable and well suited to special
applications, such as industrial tools and machinery that is not
easily run from remote sources. But, they have inherent demerit
of commutator and mechanical brushes, which undergo wear
and tear with the passage of time. In most cases, AC motors are
preferred to DC motors, in particular, an asynchronous motor
due to its simple design, low cost, reliable operation, easily
found replacements or low maintenance, variety of mounting styles, many environmental enclosures, lower weight, higher
efficiency, improved ruggedness. All these and more features
make the use of induction motor compulsory in many areas of
industrial applications. The main demerit of AC motor, when
compared with DC motor, is that its speed is more difficult to
control. AC motors can be equipped with variable
frequency/PWM drives, which provide smooth turning moment, or torque, at low speeds and complete control over the speed of
the motor up to its rated value. Variable frequency drives
improves speed control, but do create losses with reduced power
quality [1].
The advancement in Power Electronics and semiconductor technology has triggered the development of high power and
high speed semiconductor devices in order to achieve a smooth,
continuous and step less variation in motor speed. Applications
of solid state converters/inverters for adjustable speed induction
motor drive are wide spread in electromechanical systems for a
large spectrum of industrial systems,[2],[3],[4]. As far as
convectional two-level inverter is concerned, it exhibits many
problems when used in high power application [5], [6]. Poor
quality of output current and voltage of an asynchronous motor
fed by a classical/ convectional two-level inverter configuration is due to the presence of harmonic content. The presence of
significant amount of harmonic makes the motor to suffer from
severe torque pulsations, especially at low speed, which
manifest themselves in cogging of the shaft. It will also causes
undesired motor heating and Electromagnetic interference [7].
Minimization in harmonics calls for large sized filter, resulting
increased size and the cost of the system. The advancements in
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 28
the field of power electronics and microelectronics made it
possible to reduce the magnitude of harmonics with multilevel
inverters, in which the number of levels of the inverters are
increased rather than increasing the size of the filters [8]. Nowadays, multilevel inverters have been gained more attention
for high power application in recent years which operate at high
switching frequencies while producing lower order harmonic
components. Multilevel inverter not only achieves high power
ratings, but also enables the use of renewable energy sources
[9].
In this paper Single-phase three-level, four-level, and five-level inverter fed asynchronous motor drive are designed and
simulated. Both the different levels are realized by using diode
clamped multilevel inverter topology. The simulations are done
using Matlab/Simulink/SimPowerSystems software with PWM
control. The FFT spectrum for the output voltages and currents
are analyzed to study the reduction in the harmonic contents.
II. MULTILEVEL INVERTER
Multilevel inverters have drawn tremendous interest in the power industry applications. They present a new set of features
that are well suited for use in reactive power compensation.
Multilevel inverters will most importantly reduce the magnitude
of harmonics and increases the output voltage and power without the use of step-up transformer. Numerous multilevel
inverters topologies have been proposed during the last
decades. Modern research, have involved novel inverter
topologies and unique modulation techniques [10]. Basically,
three different major multilevel inverter topologies have been
reported in the literature, which includes: diode clamped
(neutral clamped) inverter, flying capacitors inverter, and
cascaded H-bridge. Multilevel inverter presented in this paper
consists of diode clamped inverter topology connected to single
phase asynchronous motor. The general function of this
multilevel inverter is to synthesize a desired voltage from several DC sources.
A. SINGLE-PHASE THREE-LEVEL, FOUR-LEVEL AND FIVE-LEVEL INVERTER CIRCUIT CONFIGURATIONS
USING DIODE CLAMPED TOPOLOGY
The neutral point inverter proposed by Nabae, and Akagi in
1981 was essentially a three-level, diode-clamped inverter [10].
The diode-clamped inverter provides multiple voltage levels
through connection of the phases to a series bank of capacitors
[11]. The main concept of this type of multilevel inverter
topology is to use diodes to limit the power devices voltage
stress. The voltage over each capacitor and each switch is . A
single-phase full bridge -level inverter needs ( voltage
source, switching devices and 8( diodes.
This topology can be extended to any number of levels by
increasing the number of capacitor banks. Diode clamped
multilevel inverter topology can be discussed under a single-
phase structures. Fig. 1 show single-phase three-level structure
of Diode Clamped Inverter.
DC
2dc
V
V dc
2dc
V
C1
C2
Da2T a2ga2
Da1
_______
1T aga1
__
Db2Tb2g
b2
iOva vb
Da1T a1ga1
Db1Tb1gb1
Da2
_______
2T a
ga2
__
Dac1
Dac2
Dbc1
Db1
_______
1Tbgb1
__
Dbc2
Db2
____
___
2Tbgb2
__
AC
Fig. 1 Power circuit for Single-phase, three-level diode clamped inverter
As shown in the fig. 1 above, a single-phase full bridge three-
level diode clamped inverter consists of two bulk capacitor (
and ), four clamping diodes ( , , and ) ,
eight antiparallel diodes ( , , ,
, , , ,
and ) and eight power switches ( , ,
, , ,
, , and
). For a given DC link voltage , the two
capacitors and are connected in series across the DC link
input. They split the DC link voltage across the capacitors with a
constant value equals to
. The clamping diodes ,
, and are used to maintain the potential across the
switches. Thus, the voltage stress of each switch is limited to
one capacitor voltage
. For a single-phase three-level full
bridge diode clamped inverter, the voltage across the output of
the two legs can be equal to 0,
and . Fig. 2 shows a
Single-phase four-level structure of Diode Clamped Inverter.
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 29
DC
3
DCV
VDC
3
DCV
C1
C2
Da1
_______
1Ta
ga1
__
Db2Tb2
gb2
iOva vb
Da1Ta1
ga1
Db1Tb1
gb1
Da2
_______
2Ta
ga2
__
Dac1
Dac2
Dbc1
Db1
_______
1Tb
gb1
__
Dbc2
Db2
_______
2Tb
gb2
__
Da3Ta3
ga3
Da2Ta2
ga2
Da3
_______
3Ta
ga3
__
Db3Tb3
gb3
Db3
_______
3Tb
gb3
__
Dac1
Dac2
Dac1
Dac23
DCVC3
AC
Fig. 2 Power circuit for Single-phase, four-level diode clamped inverter
The single-Phase Structure of diode clamped four-level inverter is illustrated in Fig. 2. DC voltage source is connected
to the inverter circuit through three capacitors connected are
connected in series. They split the DC link voltage across the
capacitors with a constant value equals to
. Thus, the voltage
stress of each switch is limited to one capacitor voltage
. For
a single-phase four-level full bridge diode clamped inverter, the
voltage across the output of the two legs can be equal to 0,
,
and . Fig. 3 shows a Single-phase five-level structure of
Diode Clamped Inverter.
DC
4
DCV
V DC
4
DCV
C1
C2
Da1
_______
1Ta
ga1
__
Db2Tb2
gb2
iOva vb
Da1Ta1
ga1 Db1Tb1
gb1
Da2
_______
2Ta
ga2
__
Dac1
Dac2
Dbc1
Db1
_______
1Tb
gb1
__
Dbc2
Db2
_______
2Tb
gb2
__
Da3Ta3
ga3
Da2Ta2
ga2
Da3
_______
3Ta
ga3
__
Db3Tb3
gb3
Db3
_______
3Tb
gb3
__
Dac1
Dac2
Dac1
Dac2
4
DCVC3
Da4Ta4
ga4
Db4Ta4
ga4
Da4
_______
4Ta
ga4
__
Db4
_______
4Tb
gb4
__
4
DCVC4
AC
Fig. 3 Power circuit for Single-phase, five-level diode clamped inverter
Finally, single-phase structure of diode clamped five-level inverter is illustrated in Fig. 3. DC voltage source is connected
to the inverter circuit through four dividing capacitors which are
connected in series. They split the DC link voltage across the
capacitors with a constant value equals to
. Thus, the voltage
stress of each switch is limited to one capacitor voltage
. For
a single-phase five-level full bridge diode clamped inverter, the
voltage across the output of the two legs can be equal to 0,
,
,
and .
B. ASYNCHRONOUS MOTOR DRIVE
Synchronous speed of Asynchronous Motor varies directly proportional to the supply frequency. Hence, by changing the
frequency, the synchronous speed and the motor speed can be
controlled below and above the normal full load speed. The
voltage induced in the stator, E is directly proportional to the
product of slip frequency and air gap flux. The Asynchronous
Motor terminal voltage can be considered proportional to the
product of the frequency and flux, if the stator voltage is
neglected. Any reduction in the supply frequency without a
change in the terminal voltage causes an increase in the air gap flux. Asynchronous motors are designed to operate at the knee
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 30
point of the magnetization characteristic to make full use of the
magnetic material. Therefore the increase in flux will saturate
the motor. This will increase the magnetizing current, distort the
line current and voltage, increase the core loss and the stator copper loss, and produce a high pitch acoustic noise. While any
increase in flux beyond rated value is undesirable from the
consideration of saturation effects, a decrease in flux is also
avoided to retain the torque capability of the motor. Therefore,
the pulse width modulation (PWM) control below the rated
frequency is generally carried out by reducing the machine
phase voltage, V, along with the frequency in such a manner
that the flux is maintained constant. Above the rated frequency,
the motor is operated at a constant voltage because of the
limitation imposed by stator insulation or by supply voltage
limitations [1]. In this paper split-phase single-phase Asynchronous Motor is used as inverter load throughout the
simulation process. Fig. 4 shows Split-phase Single-phase
Asynchronous Motor.
Fig. 4 Split-phase single-phase asynchronous motor
A three-phase symmetrical induction motor upon losing one of its stator phase supplies while running may continue to
operate as essentially a single-phase motor with the remaining
line-to-line voltage across the other two connected phases.
When the main winding coil is connected in parallel with ac
voltage, as in the split-phase single-phase asynchronous motor
of fig. 4, the current of the auxiliary winding, , leads of
the main winding. For even a larger single-phase induction
motor, that lead can be further increased by connecting a
capacitor in series with the auxiliary winding, this arrangement
brings about a Capacitor-start single-phase asynchronous motor.
III. SIMULATION MODEL AND RESULTS
Multilevel inverter fed asynchronous motor drive inverter is implemented in MATLAB SIMULINK which is shown in Fig.
5. The MATLAB SIMULINK model of Single-phase full bridge
of Diode Clamped Multilevel inverter using three-level diode
clamped configuration is shown in Fig. 5.
Fig. 5 Matlab/Simulink model of multilevel asynchronous motor drive.
The single-phase three-level diode clamped inverter output voltage after feeding to asynchronous motor is shown in Fig. 6.
The stator main winding output current with respect to single-
phase is shown in Fig. 7. The Variation in speed is shown in Fig. 8. The machine starts at no load and then at t=2.0 sec, once the
machine has reached its steady state, the load torque is increased
to its nominal value (4 N.m) in 1.0 sec. The speed increases and
settles at 1500 rpm without torque load and drops to 1450 rpm
when loaded with torque load. The Electromagnetic torque is
shown in Fig. 10. The Fast Fourier Transform (FFT) analysis is
done for the output voltage and stator main winding current and
the corresponding spectrum is shown in Fig. 11 and Fig. 12
respectively. It can be seen that the magnitude of fundamental
voltage for three-level inverter fed asynchronous motor drive is
207.6 Volts. The total harmonic distortion is 3.04 percent and the magnitude of fundamental current is 28.6 Amperes. The
total harmonic distortion is 1.43 percent.
powergui
Discrete,
Ts = 5e-005 s.
Single Phase
Asynchronous Machine
Rating 0.25Hp, 220 V,
50Hz, 1500 rpm
split
phase
Tm
m
Scope
Multilevel
Inverter System
g
Va
Vb
Load Torque
4Nm
Inverter Output
Voltage Measurement
v+-
Gain
-K-
Firing Signal
Generator
Firing Pulses
<Rotor speed (rad/s or pu)>
<Main winding current Ia (A or pu)>
<Electromagnetic torque Te (N*m or pu)>
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 31
Fig. 6 Matlab/Simulink model of Single-phase Three-level Diode Clamped Inverter
Fig. 7 Single-phase three-level inverter output Voltage
Fig. 8 Single-phase three-level inverter output Stator Main winding current
powergui
Discrete,
Ts = 5e-005 s.
Vtri4
Vtri3
Vtri2
Vtri1
Vref
Tb 33
g CE
Tb 3
g CE
Tb 22
g CE
Tb 2
g CE
Ta33
g CE
Ta3
g CE
Ta22
g CE
Ta2
g CE
Single Phase
Asynchronous Machine
split
phase
Tm
m
ScopePulse
Generator
NOT
NOT
NOT
NOT
[gb1]
[Notgb 1]
[gb2]
[Notgb 2]
[Notga 1]
[ga1]
[ga2]
[Notga 2]
From 9
[Io ]
From 8
[Vo]
From 7
[gb1]
From 6
[Notgb 1]
From 5
[gb2]
From 4
[Notgb 2]
From3
[Notga 1]
From 2
[ga1]
From 1
[ga2]
From
[Notga 2]
Embedded
MATLAB Function
SIN
T1
T2
T4
T5
a
b
d
e
fcn
DC Voltage 1
DC Voltage
D5
D4
D1
D0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
-200
-100
0
100
200
Time (s)
Ou
tpu
t V
olt
ag
e
0 10 20 30 40 50 600
5
10
15
20
25
30
Harmonic order
Fundamental (50Hz) = 203.4 , THD= 1.73%
Mag (
% o
f F
undam
enta
l)
0 1 2 3 4 5 6 7 8 9 10
-20
-10
0
10
20
30
Time (s)
Ou
tpu
t S
tato
r
Main
win
din
g C
urren
t (A
)
0 500 1000 1500 2000 2500 30000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 28.6 , THD= 1.43%
Mag
(%
of
Fu
nd
am
en
tal)
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 32
Figure 9: Variation in speed
Fig. 10 Variation in electromagnetic torque
Fig. 11 FFT analysis of voltage
Fig. 12 FFT analysis of current
The MATLAB SIMULINK model of Single-phase of four-level Diode Clamped Inverter configuration is shown in Fig. 13
0 1 2 3 4 5 6 7 8 9 100
500
1000
1500
Time (s)
Ro
tor S
peed
(rp
m)
0 100 200 300 400 500 600 700 800 900 10000
5
10
15
20
Mag (
% o
f F
undam
enta
l)
Frequency (Hz)
0 1 2 3 4 5 6 7 8 9 10
-10
0
10
Time (s)
Ele
ctr
om
ag
neti
c
torq
ue (
Nm
)
0 100 200 300 400 500 600 700 800 900 10000
5
10
15
20
Mag (
% o
f F
undam
enta
l)
Frequency (Hz)
0 1 2 3 4 5 6 7 8 9 10
-200
0
200
Selected signal: 500 cycles. FFT window (in red): 20 cycles
Time (s)
0 500 1000 1500 2000 2500 30000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 207.6 , THD= 3.04%
Mag
(%
of
Fu
nd
am
en
tal)
0 1 2 3 4 5 6 7 8 9 10
-20
-10
0
10
20
30
Time (s)
Ou
tpu
t S
tato
r
Main
win
din
g C
urr
en
t (A
)
0 500 1000 1500 2000 2500 30000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 28.6 , THD= 1.43%
Mag
(%
of
Fu
nd
am
en
tal)
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 33
Fig. 13 Matlab/Simulink model of single-phase four-level diode clamped inverter
The single-phase four-level diode clamped inverter output voltage after feeding to asynchronous motor is shown in Fig.
14. The output stator main winding current with respect to
single-phase is shown in Fig. 15. The Variation in speed is
shown in Fig. 16. The speed increases and settles at 1500 rpm
without torque load and drops to 1450 rpm when loaded with
torque load of 4 Nm. The Electromagnetic torque is shown in Fig. 17. The Fast Fourier Transform (FFT) analysis is done for
the voltage and output stator main winding current and the
corresponding spectrum is shown in Fig. 18 and Fig. 19
respectively. It can be seen that the magnitude of fundamental
voltage for four-level inverter fed asynchronous motor drive is 209.5 Volts. The total harmonic distortion is 2.32 percent and
the magnitude of fundamental current is 28.74 Amperes. The
total harmonic distortion is 0.99 percent.
Fig. 14 Single-phase four-level inverter output voltage
powergui
Discrete,
Ts = 5e-005 s.
Vtri6
Vtri5
Vtri4
Vtri 3
Vtri2
Vtri1
Vref
Tb 33
g CE
Tb 3
g CE
Tb 22
g CE
Tb 2
g CE
Tb 11
g CE
Tb 1
g CE
Ta33
g CE
Ta3
g CE
Ta22
g CE
Ta2
g CE
Ta11
g CE
Ta1
g CE
Single Phase
Asynchronous Machine
split
phase
Tm
m
Pulse
Generator
NOT
NOT
NOT
NOT
NOT
NOT
[gb2]
[NOTgb 2] [gb3]
[NOTgb 3]
[NOTga 1]
[ga1]
[NOTga 2]
[ga2]
[gb1]
[NOTgb 1]
[NOTga 3]
[ga3]
From 9
NOTgb 1]
From 8
[gb3]
From 7
[gb2]
From 6
[gb1]
From 5
NOTga 3]
From 4
NOTga 2]
From 3
NOTga 1]
From 2
[ga3]
From 13
[Io ]
From 12
[Vo]
From 11
NOTgb 3]
From 10
NOTgb 2]
From 1
[ga2]
From
[ga 1]
Embedded
MATLAB Function
SIN
T1
T2
T3
T4
T5
T6
a
b
c
d
e
f
fcn
DC Voltage 3
DC Voltage 2
DC Voltage 1
D7
D6
D5
D4
D3
D2
D1
D0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
-200
-100
0
100
200
Time (s)
Ou
tpu
t V
olt
ag
e (
V)
0 100 200 300 400 500 6000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 209.5 , THD= 2.32%
Mag
(%
of
Fu
nd
am
en
tal)
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 34
Fig. 15 Single-phase four-level inverter output stator main winding current
Fig. 16 Variation in speed
Fig. 17 Variation in electromagnetic torque
Fig. 18 FFT analysis of voltage
Fig.19 FFT analysis of current
0 1 2 3 4 5 6 7 8 9 10
-20
0
20
Time (s)
Ou
tpu
t S
tato
r
Main
win
din
g C
urren
t (A
)
0 500 1000 1500 2000 2500 30000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 28.74 , THD= 0.99%
Mag
(%
of
Fu
nd
am
en
tal)
0 1 2 3 4 5 6 7 8 9 100
500
1000
1500
Time (s)
Ro
tor
Sp
eed
(rp
m)
0 100 200 300 400 500 600 700 800 900 10000
5
10
15
20
Mag (
% o
f F
undam
enta
l)
Frequency (Hz)
0 1 2 3 4 5 6 7 8 9 10
-10
0
10
Time (s)
Ele
ctr
om
ag
neti
c
To
rqu
e (
Nm
)
0 100 200 300 400 500 600 700 800 900 10000
5
10
15
20
Mag (
% o
f F
undam
enta
l)
Frequency (Hz)
0 1 2 3 4 5 6 7 8 9 10
-200
0
200
Selected signal: 500 cycles. FFT window (in red): 20 cycles
Time (s)
0 500 1000 1500 2000 2500 30000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 209.5 , THD= 2.32%
Mag
(%
of
Fu
nd
amen
tal)
0 1 2 3 4 5 6 7 8 9 10
-20
0
20
Time (s)
Ou
tpu
t S
tato
r
Mai
n w
ind
ing
Cu
rren
t (A
)
0 500 1000 1500 2000 2500 30000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 28.74 , THD= 0.99%
Mag
(%
of
Fu
nd
amen
tal)
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 35
The MATLAB SIMULINK model of Single-phase of five-level Diode Clamped Inverter configuration is shown in Fig. 20
Fig. 20 Matlab/Simulink model of single-phase five-level diode clamped inverter
The single-phase five-level diode clamped inverter output
voltage after feeding to asynchronous motor is shown in Fig.
21. The output stator main winding current with respect to single-phase is shown in Fig. 22. The Variation in speed is
shown in Fig. 23. The speed increases and settles at 1500 rpm
without torque load and drops to 1450 rpm when loaded with
torque load of 4 Nm. The Electromagnetic torque is shown in
Fig. 24. The Fast Fourier Transform (FFT) analysis is done for
the voltage and output stator main winding current and the
corresponding spectrum is shown in Fig. 25 and Fig. 26
respectively. It can be seen that the magnitude of fundamental
voltage for five-level inverter fed asynchronous motor drive is
208.2 Volts. The total harmonic distortion is 1.70 percent and
the magnitude of fundamental current is 28.58 Amperes. The
total harmonic distortion is 0.84 percent.
powergui
Discrete,
Ts = 5e-005 s.
Vtri8
Vtri7
Vtri6Vtri5
Vtri 4
Vtri 3
Vtri 2
Vtri1
Vcontrol
Tb 4
g CE
Tb 3
g CE
Tb 2
g CE
Tb 1
g CE
Ta4
g CE
Ta3
g CE
Ta2
g CE
Ta1
g CE
Single Phase
Asynchronous Machine
split
phase
Tm
mPulse
Generator
NTb 4
g CE
NTb 3
g CE
NTb 2
g CE
NTb 1
g CE
NTa 4
g CE
NTa 3
g CE
NTa 2
g CE
NTa1
g CE
NOT
NOT
NOT
NOT
NOT
NOT
NOT
NOT
[gb4]
[NOTgb 4]
[NOTga 1]
[ga1]
[NOTga 2]
[ga2]
[NOTga 3]
[ga3]
[gb1][NOTgb 1]
[gb2]
[NOTgb 2]
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[NOTgb 3]
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[ga4]
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NOTgb 3]
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NOTgb 4]
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NOTga 4]
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NOTga 3]
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NOTga 2]
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NOTga 1]
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[ga 4]
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[gb 1]
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NOTgb 1]
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NOTgb 2]
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[ga 1]
Embedded
MATLAB Function
SIN
T1
T2
T3
T4
T5
T6
T7
T8
a
b
c
d
e
f
g
h
fcn
DC Voltage 3
DC Voltage 2
DC Voltage 1
DC Voltage
D9
D8
D7
D6
D5
D4
D3
D2
D11
D10
D1
D0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
-200
-100
0
100
200
Time (s)
Ou
tpu
t V
olt
ag
e (
V)
0 50 100 150 200 250 300 350 400 450 5000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 203.8 , THD= 0.89%
Mag
(%
of
Fu
nd
am
en
tal)
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 36
Fig. 21 Single-phase five-level inverter output voltage
Fig. 22 Single-phase five-level inverter output stator main winding current
Fig. 23 Variation in speed
Fig. 24 Variation in electromagnetic torque
Fig. 25 FFT analysis of voltage
0 1 2 3 4 5 6 7 8 9 10
-20
0
20
Time (s)
Ou
tpu
t S
tato
r
Main
win
din
g C
urren
t (A
)
0 500 1000 1500 2000 2500 30000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 28.58 , THD= 0.84%
Mag
(%
of
Fu
nd
am
en
tal)
0 1 2 3 4 5 6 7 8 9 100
500
1000
1500
Time (s)
Ro
tor
Sp
eed
(rp
m)
0 500 1000 1500 2000 2500 30000
500
1000
1500
2000
Frequency (Hz)
Fundamental (50Hz) = 11.82 , THD= 98.34%
Mag (
% o
f F
undam
enta
l)
0 1 2 3 4 5 6 7 8 9 10
-10
0
10
Time (s)
Ele
ctr
om
ag
neti
c
To
rqu
e (
Nm
)
0 100 200 300 400 500 600 700 800 900 10000
5
10
15
20
Mag (
% o
f F
undam
enta
l)
Frequency (Hz)
0 1 2 3 4 5 6 7 8 9 10
-200
0
200
Selected signal: 500 cycles. FFT window (in red): 20 cycles
Time (s)
0 500 1000 1500 2000 2500 30000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 208.2 , THD= 1.70%
Mag
(%
of
Fu
nd
amen
tal)
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 37
The results are tabulated in Table I below:
TABLE I
THE ANALYSIS OF THREE-LEVEL, FOUR-LEVEL and FIVE- LEVEL DIODE
Parameters Diode Clamped Multilevel Inverter
Three-level Inverter Four-level
Inverter
Five-level
Inverter
Voltage
Level (V)
207.6 209.5 208.20
THD for
Voltage (%)
3.04 2.32 1.70
Current
Level (A)
28.6 28.74 28.58
THD for
Current (%)
1.43 0.99 0.84
Fig. 26 FFT analysis of Current
IV. CONCLUSIONS
Three-level, Four-level and Five-level Diode Clamped inverter fed asynchronous motor drive are simulated using the
blocks of Matlab/Simulink/SimPowerSystems. The results of
three-level, four-level and five-level systems are compared. It is observed that the total harmonic distortion produced by the five-
level inverter system is less than those of three-level and four-
level inverter fed drive system. Therefore the heating due to
five-level inverter system is less than those of three-level and
four-level inverter fed drive system. The switching losses due to
five-level inverter system is higher than those of three-level and
four-level inverter fed system because of high number of power
switches involved in the design. The simulation results of
voltage, current, electromagnetic torque, speed and spectrum are
presented. This drive system can be used in industries where
adjustable speed drives are required to produce output with reduced harmonic content. The scope of this work is the
modeling and simulation of three-level, four-level and five-level
inverter fed asynchronous motor drive systems. An Improved
Multilevel topology will be used to drive the asynchronous
motor in future work. Five-level or higher level inverter system
is a viable alternative since it has better performance.
REFERENCES
[1] Manasa, S., Balajiramakrishna, S., Madhura, S. and Mohan, H. M.,
“Design and Simulation of Three Phase Five Level and Seven Level
inverter fed Induction Motor Drive with Two Cascaded H-Bridge
Configuration”, International Journal of Electrical and Electronics
Engineering (IJEEE), , vol. 1, pp. 2231-5284 2012.
[2] Tolbert, L. M., Peng, F. Z. and Habetler, T. G., “Multilevel Converters for
Large Electric Drives”, IEEE Transactions on Industry Applications, vol.
35, no. 1, pp. 36–44, 1999.
[3] Pandian, G. and Rama, R. S., “Implementation of Multilevel Inverter-Fed
Induction Motor Drive”, Journal of Industrial Technology, vol. 24, pp.
109–119, 2008.
[4] Neelashetty, Kashappa and Ramesh, Reddy, “Performance Of Voltage
Source Multilevel Inverter – Fed Induction Motor Drive Using
Simulink”, ARPN Journal of Engineering and Applied Sciences, vol. 6,
no. 6, pp. 1819-6608, 2011.
0 1 2 3 4 5 6 7 8 9 10
-20
0
20
Time (s)
Ou
tpu
t S
tato
r
Main
win
din
g C
urren
t (A
)
0 500 1000 1500 2000 2500 30000
20
40
60
80
100
Frequency (Hz)
Fundamental (50Hz) = 28.58 , THD= 0.84%
Mag
(%
of
Fu
nd
am
en
tal)
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
ISSN: 2231-5381 http://www.ijettjournal.org Page 38
[5] Rodríguez, J., Lai, J. S. and Peng, F. Z., “Multilevel inverters: A Survey
of Topologies, Controls, and Applications”, IEEE Transactions on
Industrial Electronics, vol. 49, no. 4, pp. 724-738, 2002.
[6] Lai, J. S. and Peng, F. Z., “Multilevel Converters-a New Breed of Power
Converters”, IEEE Transactions on Industry Applications, vol. 32, no.
3, pp. 509-517, 1996.
[7] Shivakumar, E.G., Gopukumar, K.., Sinha S. K. and Ranganathan, V.T.,
“Space Vector PWM Control of Dual Inverter Feed-open-end
Winding induction Motor Drive”, IEEE APEC Conf., vol. 1, pp. 399-
405, 2001
[8] Dixon, J. and Moran, L.,” High-level Multi-Step Inverter Optimization
using a Minimum number of Power Transistors “, IEEE Tran. Power
Electron, vol. 21, no.23, pp. 30-337, 2006.
[9] Murugesan, M., Sakthivel, R., Muthukumaran, E and Sivakumar, R.
“Sinusoidal PWM Based Modified Cascaded Multilevel Inverter”,
International Journal of Computational Engineering Research, vol. 2,
no. 2, pp. 529-539, 2012.
[10] Surin, Khomfoi and Tolbert, L. M., “Multilevel Power Converters”,
University of Tennessee, www.google.com/m/url/channel=n&w
client/wed.eecs.utk.edu/~tolbert/publications/multilevel_book_chapter.
pdf, 2012.
[11] Kith Corzine, “Operation and design of Multilevel Inverters”,
Developed for the office of Naval research, 2003.