International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
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
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, singlephase 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
ISSN: 2231-5381
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.
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
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
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 fivelevel 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.
phase structures. Fig. 1 show single-phase three-level structure
of Diode Clamped Inverter.
g a1
g
Dac1 a2 T a2 Da2
va i
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-
ISSN: 2231-5381
T b1 Db1
C1 Vdc
2
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.
g b1
T a1 Da1
DC
C2
V
dc
2
b2
vb
O
__
g a1 ___ ____
T a1 Da1
Dac2
V dc
Dbc1 g T D
b2 b2
__
g a2 ___ ____
T a2 Da2
AC
__
g b1 ___
T b1 Db1
Dbc2
__
___
g b2
T b2 Db2
____
____
Fig. 1 Power circuit for Single-phase, three-level diode clamped inverter
As shown in the fig. 1 above, a single-phase full bridge threelevel 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.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
g
a1
T
a1
C
1
g
D
b1
g
a1
T
C
1
D
a2
ac1
T
D
D
a2
a2
a3
b2
bc1
g
VDC
4
g
g
T
D
b2
a2
b1
a1
T
b1
D
b2
D
b3
D
b1
b1
VDC
3
g
g
D
a1
D
b1
a1
T
b2
C
2
T
g
b2
D
a2
a2
b3
D
a3
a3
D
D
b2
g
T
T
b3
bc1
ac1
VDC
4
T
g
a4
T
g
a4
a4
D
a4
T
D
a4
b4
D
ac1
D g
ac1
DC
V
DC
C
2
a3
VDC
3
T
D
DC
ac2
ac2
a1
gb1
D
Da1
___
b1
C
4
Db1
VDC
4
D
__
C
3
VDC
3
D
___
T
b1
____
Db1
D
a2
g b2
____
Da2
D
___
T
b2
____
Db2
ac2
g a3
__
___
T
____
a3
Da3
___
T
b3
____
Db3
__
__
g a4
gb3
___
T
____
a4
Da4
gb4
___
T
b4
____
Db4
__
___
T
a2
ac2
gb2
____
Da2
___
T
b2
D
____
Db2
ac2
__
ga3
T
__
____
bc2
ga2
Da1
__
___
ac2
T
g b1
____
a1
bc2
g a2
__
AC
____
___
T
__
b
___
T
VDC
4
v
__
b
__
__
g a1
D
3
O
ga1
b3
C
a
v
ac1
AC
DC
ac1
v i
D
D
b3
a3
V
D
O
a
b3
a3
i
v
g
T
D
Fig. 3 Power circuit for Single-phase, five-level diode clamped inverter
__
___
T
a3
____
Da3
gb3
___
T
b3
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
Db3 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, ,
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.
ISSN: 2231-5381
,
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
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
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.
of Diode Clamped Multilevel inverter using three-level diode
clamped configuration is shown in Fig. 5.
Discrete,
Ts = 5e-005 s.
powergui
Load Torque
4Nm
Va
+
v
-
Inverter Output
Voltage Measurement
<Main winding current Ia (A or pu)>
Tm
split
phase
g
m
Firing Pulses
Gain
<Electromagnetic torque Te (N*m or pu)>
Vb
Firing Signal
Generator
-K<Rotor speed (rad/s or pu)>
Single Phase
Asynchronous Machine
Rating 0.25Hp, 220V,
50Hz, 1500 rpm
Scope
Multilevel
Inverter System
Fig. 5 Matlab/Simulink model of multilevel asynchronous motor drive.
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
ISSN: 2231-5381
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 singlephase 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.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
Discrete,
Ts = 5e-005 s.
powergui
[gb 1]
Tb 2
E
E
Ta 2
From 8
[gb 2]
[ga 2]
DC Voltage
Scope
[Io ]
Pulse
Generator
D0
[ga 2]
From 5
Tm
C
From 9
g
From 1
m
split
phase
Tb 3
D4
SIN
Single Phase
Asynchronous Machine
[Notga 2]
NOT
a
E
E
Ta 3
g
[Vo]
C
From 7
C
From 2
C
g
g
[ga 1]
Vref
[Notga 1]
[Notgb 1]
[ga 1]
Vtri2
NOT
From 6
C
C
g
b
g
From3
T1
Ta 22
[Notga 1]
Tb 22
Vtri1
T2 fcn
E
E
D1
D5
[Notgb 2]
NOT
[Notgb 2]
From
[Notgb 1]
Ta 33
From 4
E
NOT
e
Tb 33
[gb 1]
E
T5
Embedded
MATLAB Function
Output Voltage
Fig. 6 Matlab/Simulink model of Single-phase Three-level Diode Clamped Inverter
200
100
0
-100
-200
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Time (s)
Fig. 7 Single-phase three-level inverter output Voltage
Fundamental (50Hz) = 203.4 , THD= 1.73%
Output Stator
Main winding Current (A)
30
Mag (% of Fundamental)
25
20
15
30
20
10
0
10 -10
5 -20
0
0
1
0
2
10
3
4
20
5
30
Time (s)
6
7
40
8
9
10
50
60
Fig. 8 Single-phase three-level inverter output Stator Main winding Harmonic
current order
Fundamental (50Hz) = 28.6 , THD= 1.43%
100
Mag (% of Fundamental)
Vtri4
g
[Notga 2]
DC Voltage 1
T4
g
[gb 2]
C
Vtri3
C
d
80
60
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20
0
0
500
1000
1500
2000
2500
3000
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
Rotor Speed (rpm)
1500
1000
500
0
0
1
2
3
4
5
Time (s)
6
7
8
9
10
Mag (% of Fundamental)
Electromagnetic
torque (Nm)
Figure 9: Variation in speed
20
10
15
Selected signal: 500 cycles. FFT window (in red): 20 cycles
200 0
10
0
-10
5
-200 0
1
0 0
2
1
3
2
3
Fig. 10 Variation in0 electromagnetic
torque
100
200
4
300
4
5
Time (s)
5
400 Time (s)
500
Frequency (Hz)
6
7
6
600
7
700
8
9
8
800
900
10
9
1000
10
30
Mag (% of Fundamental)
Mag (% of Fundamental)
Output Stator
Main winding Current (A)
Fundamental (50Hz) = 207.6 , THD= 3.04%
20
100
15
80
20 6010
10 40
0
5
20
-10
0
0
-20
0
0
100
500
0
1
200
2
Fig. 11 FFT analysis of voltage
300
1000
3
400
500
1500 (Hz)
Frequency
Frequency (Hz)
4
5
Time (s)
600
700
800
2500
7
8
2000
6
900
1000
3000
9
10
Fundamental (50Hz) = 28.6 , THD= 1.43%
Mag (% of Fundamental)
100
80
60
40
20
0
0
500
1000
1500
Frequency (Hz)
2000
2500
3000
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
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
[gb 1]
From
[ga 3]
From 6
C
g
g
[ga 1]
C
Discrete,
Ts = 5e-005 s.
powergui
Tb 1
E
Ta 1
[NOTga 3]
NOT
From 7
split
phase
Ta 2
D2
[ga 3]
m
E
[ga 1]
[NOTga 1]
d
D0
[NOTgb 3]
Single Phase
Asynchronous Machine
g
From 8
D4
Tb 3
Ta 3
e
[NOTgb 2]
DC Voltage 2
[gb 3]
E
NOT
T4
E
Vtri1
g
NOT
T3 fcn
[gb 3]
From 2
c
C
T2
Vtri2
D6
Tb 2
E
b
[gb 2]
Tm
C
g
[NOTga 2]
T1
Vtri 3
Pulse
Generator
From 1
[ga 2]
g
DC Voltage 3
a
C
[ga 2]
SIN
C
NOT
E
Vref
T5
Vtri4
NOT
f
T6
[gb 2]
NOTga 1]
NOT
From 9
D7
Ta 11
[gb 1]
Tb 11
E
E
D3
NOTga 2]
NOTgb 2]
From 4
g
DC Voltage 1
From 10
C
[Vo]
C
C
g
Vtri6
g
NOTgb 1]
From 3
[NOTgb 1]
g
Embedded
MATLAB Function
D5
C
Vtri5
From 12
[Io ]
Tb 22
E
D1
From 13
E
Ta 22
NOTga 3]
From 11
E
Tb 33
E
Ta 33
C
g
C
g
NOTgb 3]
From 5
Fig. 13 Matlab/Simulink model of single-phase four-level diode clamped inverter
Output Voltage (V)
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.
200
100
0
-100
-200
0
0.05
0.1
0.15
0.2
Time (s)
0.25
0.3
0.35
0.4
Fig. 14 Single-phase four-level inverter output voltage
Fundamental (50Hz) = 209.5 , THD= 2.32%
Mag (% of Fundamental)
100
80
60
40
ISSN:
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20
0
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Output Stator
Main winding Current (A)
International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
20
0
-20
0
5
6
Time (s)
Fig. 15 Single-phase four-level inverter output stator main winding current
Fundamental (50Hz) = 28.74 , THD= 0.99%
2
3
4
7
8
9
10
Rotor Speed (rpm)
1500
1000
80
500
60
0
0
1
2
3
4
40
Fig. 16 Variation in speed
5
Time (s)
6
7
8
9
10
20
Electromagnetic
(Nm)
Fundamental)
Mag (% of Torque
Mag (% of Fundamental)
100
1
0
20
10
0
500
150
1000
1500
Frequency (Hz)
2000
2500
3000
Selected signal: 500 cycles. FFT window (in red): 20 cycles
200
10
-10
0
-200
0
Mag (% of Fundamental)
Output Stator
Mag (%(A)of Fundamental)
Main winding Current
Fig.
50
1
2
3
4
5
6
7
8
9
10
Tim e (s )
170 Variation 1in
2
electromagnetic
0
100
3
torque
200
4
300
5
Time (s)
6
7
400
500
Frequency (Hz)
600
400
500
1500 (Hz)
Frequency
600
8
9
700
800
700
800
900
10
1000
Fundamental (50Hz) = 209.5 , THD= 2.32%
20
100
15
80
60 10
40 20
5
20
0
0
0
0
0-20
100
500
200
300
1000
2000
900
2500
1000
3000
Frequency (Hz)
0
1
Fig. 18 FFT
analysis
of voltage2
3
4
5
Time (s)
6
7
8
9
10
Fundamental (50Hz) = 28.74 , THD= 0.99%
Mag (% of Fundamental)
100
80
60
40
20
0
0
500
1000
1500
Frequency (Hz)
2000
2500
3000
Fig.19 FFT analysis of current
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
From
[gb 1]
Ta 1
C
C
g
[ga 1]
Discrete,
Ts = 5e-005 s.
powergui
g
The MATLAB SIMULINK model of Single-phase of five-level Diode Clamped Inverter configuration is shown in Fig. 20
From 15 Tb 1
[NOTgb 3]
split
phase
g
C
From 12
Tb 4
From 3
D0
D4
Ta 4
E
[gb 3]
C
g
[gb 4]
E
NOT
[ga 1]
NOTga 1]
g
From 4
[gb 2]
T6
g
D11
DC Voltage
NOT
NOTgb 2]
g
NOTga 2]
Vtri8
From 5
From 10
D7
E
NTb 2
E
NTa 2
Embedded
MATLAB Function
D9
g
[gb 1]
C
[NOTgb 1]
h
E
D3
T7
NOTgb 1]
NTb 1
From 11
NTa 1
[NOTga 1]
E
Vtri1
C
NOT
C
f
DC Voltage 2
NOT
g
[NOTgb 2]
C
e
NOTga 3]
C
g
D1
g
NOTgb 3]
From 6
DC Voltage 1
From 9
NTa 3
C
T5
T8
D6
Tb 3
[gb 4]
Single Phase
Asynchronous Machine
[ga 4]
NOT
T4 fcn
g
m
[NOTgb 4]
T3
Vtri7
Pulse
Generator
Ta 3
E
d
[NOTga 2]
From 13
g
NOT
D10
D2
E
c
From 2
DC Voltage 3
[ga 2]
Tm
C
[NOTga 3]
NOT
Vtri6
[gb 3]
[ga 3]
T2
Vtri 3
g
D8
[ga 3]
b
C
NOT
T1
E
[NOTga 4]
Vtri 4
Vtri5
Tb 2
E
Vcontrol
C
g
Ta 2
From 1
a
C
[ga 2]
[ga 4]
SIN
Vtri 2
E
E
[gb 2]
From 14
NTb 3
NOTgb 4]
C
From 8
g
C
g
NOTga 4]
From 7
E
E
D5
NTa 4
E
E
NTb 4
Fig. 20 Matlab/Simulink model of single-phase five-level diode clamped inverter
Output Voltage (V)
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.
200
100
0
-100
-200
0
0.05
0.1
0.15
0.2
Time (s)
0.25
0.3
0.35
0.4
Fundamental (50Hz) = 203.8 , THD= 0.89%
% of Fundamental)
100
ISSN:
2231-5381
80
60
40
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
Output Stator
Main winding Current (A)
Fig. 21 Single-phase five-level inverter output voltage
20
0
-20
0
1
2
3
4
5
Time (s)
6
7
8
7
8
9
10
Fig. 22 Single-phase five-level inverter output stator main winding current
Fundamental (50Hz) = 28.58 , THD= 0.84%
Rotor Speed (rpm)
Mag (% of Fundamental)
100
1500
80
1000
60
500
40
0
200
1
2
Fig. 23 Variation
in speed
0
Mag (% of Fundamental)
Electromagnetic
Torque (Nm)
0
3
4
500
5
Time (s)
6
1000
2000
Fundamental (50Hz) 1500
= 11.82 , THD= 98.34%
Frequency (Hz)
9
2500
10
3000
2000
10
1500
0
1000
Selected signal: 500 cycles. FFT window (in red): 20 cycles
-10
500200
0
0
1
2
3
0
500
1000
Fig. 24 Variation
in electromagnetic torque
-200
0
Mag (% of Fundamental)
Mag (% of Fundamental)
4
0
1
2
3
5
Time (s)
6
5
Time (s)
6
1500
Frequency (Hz)
4
7
8
9
2000
2500
7
8
700
800
10
3000
9
10
20
Fundamental (50Hz) = 208.2 , THD= 1.70%
15
100
10
80
60
5
40
200
0
0
100
0
500
200
300
1000
400
500
Frequency (Hz)
1500
Frequency (Hz)
600
2000
2500
900
1000
3000
Fig. 25 FFT analysis of voltage
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
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
Output Stator
Main winding Current (A)
Three-level Inverter
Voltage
Level (V)
THD for
Voltage (%)
Current
Level (A)
THD for
Current (%)
20
0
-20
0
1
2
Four-level
Inverter
Five-level
Inverter
207.6
209.5
208.20
3.04
2.32
1.70
28.6
28.74
28.58
1.43
0.99
0.84
3
4
5
Time (s)
6
7
8
9
10
Fundamental (50Hz) = 28.58 , THD= 0.84%
Mag (% of Fundamental)
100
80
60
40
20
0
0
500
1000
1500
Frequency (Hz)
2000
2500
3000
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 fivelevel inverter system is less than those of three-level and fourlevel 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
ISSN: 2231-5381
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.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 1 - Jun 2014
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
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[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. 399405, 2001
[8]
Dixon, J. and Moran, L.,” High-level Multi-Step Inverter Optimization
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[5]
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[9]
[10]
[11]
Murugesan, M., Sakthivel, R., Muthukumaran, E and Sivakumar, R.
“Sinusoidal PWM Based Modified Cascaded Multilevel Inverter”,
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no. 2, pp. 529-539, 2012.
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.
Kith Corzine, “Operation and design of Multilevel Inverters”,
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