Analysis Approach for Five Phase Two-Level Voltage Source Inverter with PWM Technique for Induction Motor Drive

IJSRD - International Journal for Scientific Research & Development| Vol. 1, Issue 3, 2013 | ISSN (online): 2321-0613
All rights reserved by www.ijsrd.com 488
Analysis Approach for Five Phase Two-Level Voltage Source Inverter
with PWM Technique for Induction Motor Drive
Ankur P. Desai1
Vijay G. Bhuva2
1
Student 2
Assitant Professor
1,2
Shantilal Shah Engineering College, Bhavnagar, Gujarat, India
Abstract— this paper gives idea of comparison of five phase
two-level voltage inverter (FPTLVSI) without filter circuit
and control scheme and FPTLVSI with filter circuit and
PWM control scheme for induction motor drive. The paper
demonstrates using mat lab simulations about comparison in
term of harmonics analysis for different firing angles and
find best angle suitable for output with minimum harmonics
for FPTLVSI without filter circuit and control scheme and
harmonics analysis of FPTLVSI with filter and PWM
control scheme. This paper suggests simulation of
comparison of harmonics point of view five phase two-level
voltage inverter (FPTLVSI) without filter circuit and control
scheme and with filter circuit and PWM control scheme for
induction motor drive.
Keywords: Modelling of five phase two-level voltage
inverter (FPTLVSI), PWM control scheme for FPTLVSI
I. INTRODUCTION
RESEARCH interest in the area of multiphase machines has
been steadily increasing over the past decade [1].The newest
developments are application-driven (marine electric
propulsion, electric vehicles (EVs) and hybrid electric
vehicles (HEVs), more electric aircraft, locomotive traction,
and high-power applications in general) and the
consequence of the advantages offered by multiphase
machines, when compared to the three-phase equivalents.
These are predominantly related to the possibility of
reduction of the converter per-phase rating for the given
machine power and to significantly improved fault
tolerance, since an n-phase machine can continue to operate
with a rotating field as long as no more than (n-3) phases are
faulted. A further advantage exists if the multiphase
machine is designed with concentrated stator windings,
since it then becomes possible to enhance the torque
production by injection of the low-order stator current
harmonics of an appropriate order. Five phase induction
machine drive.
Fig.1: Block diagram of five phase induction motor drive
A simple open-loop five-phase drive structure is
elaborated in. The dc link voltage is adjusted from the
controlled rectifier by varying the conduction angles of the
thyristors. The frequency of the fundamental output is
controlled from the IGBT based voltage source inverter. The
subsequent section describes the implantation issues of
control of a five-phase voltage source inverter. The
motivation behind choosing this structure lies in the fault
tolerant nature of a five-phase drive system. It has been
advantage of five phase induction motor drive like reduction
in phase current, reliable in faulty conditions, reduction in
current ripple.
II. BLOCK DIAGRAM FIVE PHASE TWO LEVEL
VOLTAGE SOURCE INVERTER MODEL
As shown in fig.2 each switch in the circuit consists of two
power semiconductor devices connected in anti-parallel.
One of these is a fully controllable semiconductor, such as a
bipolar transistor, MOSFET, or IGBT, while the second is a
diode.
Fig. 2: Power Circuit topology of a FPTLVSI
The upper and lower power switches of the same
leg are complimentary in operation, i.e. if the upper switch
is ‘ON’ the lower must be ‘OFF,’ and vice-versa. As shown
in fig.3, Dead time is done to avoid shorting the DC supply.
Fig. 3: Illustration for dead time

Analysis Approach for Five Phase Two-Level Voltage Source Inverter with PWM Technique for Induction Motor Drive
(IJSRD/Vol. 1/Issue 3/2013/0021)
III. HARMONICS ANALYSIS OF FPTLVSI.
This section presents the comprehensive analysis of
simulation results. The performance of two different
conduction modes are elaborated in terms of the harmonic
content in the phase voltages, line voltages and the
distortion in the ac side line current.
The Fourier series of the phase-to-neutral voltage
for 180° conduction mode is obtained as;
 
1
sin sin3
3
2 1 1
sin 7 sin9
7 9
1
sin11 .....
11
dc
t t
V t t t
t
V
 
 


 
  
 
   
 
 
 
  
… (1)
From above equation (1) it follows that the
fundamental component of the output phase-to-neutral
voltage has an RMS value equal to
1
2
0.45dc dcV V V
 
… (2)
The Fourier series of the phase-to-neutral voltage
for 120° conduction mode is obtained as;
    
1,2,3,..
cos 2 1 sin 2 1
2 10
( )
2 1
dc
n
n n t
V t
n
V





  
   
  
 
  

… (3)
From above equation (3) it follows that
the fundamental component of the output phase-to-neutral
voltage has an RMS value equal to
1
2
cos 0.428
10dc dcV V V


 
  
  … (4)
As per the equation of (4) loss in fundamental
voltage in 120° conduction mode is of the order of 4.89%
compared to 180° conduction mode. This loss will affect the
loss of torque in the driven machine and subsequently the
load will be affected. However, the drop in the torque is not
very significant compared to the benefits obtained due to
better harmonic performance.
Performance comparison in terms of harmonic
content in output phase voltage, for different conduction
modes are presented in fig.10 to 11. It is clearly seen that the
harmonic content reduces significantly with reduction in
conduction angle. The harmonic content is largest in 180
degree conduction mode and it is least in 120 degree
conduction mode. However, the best utilization of available
dc link voltage is possible with conventional ten step mode
(180 degree conduction mode). It can thus be concluded that
a trade-off exist between the loss in fundamental and
corresponding gain in terms of lower harmonic content in
output waveform is obtained by using 120 degree
conduction mode.
A comparison of total harmonic distortion in the
output phase voltages of five-phase voltage source inverter
for different conduction angle is presented. The conduction
angles considered are 180°, 162°, 144°, 126°, and 108°.
Thus two more conduction states are included when
compared to further prove the superiority of control at 120°
conduction mode. It is observed that the lowest THD is
obtained for 120° conduction mode.
Fig.4 is also mat lab simulation of FPTLVSI with
balance resistive load. It can be simulated and analysis for
different firing angles and takes measurement of harmonics
behavior.
Following Table: 1 shows THD Vs different firing
angles for FPTLVSI without any filter circuit.
Fig.4: Matlab/simulink of FPTLVSI
Firing anglesTHD(Total Harmonics Distortion)
108 53.63
110 49.96
115 47.3
118 36.99
120 27.03
125 36.28
126 35.68
130 38.51
144 42.98
180 46.68
Table. 1: Different firing angles and related THD for
harmonic analysis of FPTLVSI
Fig.5 curve of different firing angles and related THD for
harmonic analysis of FPTLVSI
0
20
40
60
0 100 200
THD
Firing Angle of FPTLVSI without Filter
circuit
Harmonics Analysis of
FPTLVSI without
Filter Circuit
Series1

IV. THE CARRIER-BASED PULSE WIDTH
MODULATION (PWM) TECHNIQUE FOR FIVE PHASE
INDUCTION MOTOR DRIVE
Fig. 6: Single phase half –bridge VSI
As mentioned earlier, it is desired that the ac output
voltage, o aNv v
follow a given waveform (e.g.
sinusoidal) on a continuous basis by properly switching the
power valves. The carrier-based PWM technique fulfils such
a requirement as it defines the on- and off-states of the
switches of one leg of a VSI by comparing a modulating
signal cv (desired ac output voltage) and a triangular
waveform v (carrier signal). In practice, when cv v
the switch S+ is on and the switch S− is off; similarly, when
cv < v the switch S+ is off and the switch S− is on.
A special case is when the modulating signal cv
is a sinusoidal at frequency c
f and amplitude cv , and the
triangular signal v is at frequency f  and amplitude
v . This is the sinusoidal PWM (SPWM) scheme. In this
case, the modulation index am (also known as the
amplitude-modulation ratio) is defined as
c
a
v
m
v

… (1)
And the normalized carrier frequency fm (also known as
the frequency-modulation ratio) is
f
c
f
m f


… (2)
Figure 7 clearly shows that the ac output voltage
0 aNv v is basically a sinusoidal waveform plus
harmonics, which features: (a) the amplitude of the
fundamental component of the ac output voltage 01v
satisfying the following expression:
01 1
2
i
aN a
v
v v m  …(3)
for am ≤ 1, which is called the linear region of
the modulating technique (higher values of ma leads to over
modulation); (b) for odd values of the normalized carrier
frequency fm the harmonics in the ac output voltage
appear at normalized frequencies h
f centred around and
fm its multiples, specifically,
f
h l km  1,2,3,.....l 
… (4)
Where 2,4,6,...k 
For 1,3,5,.....l 
And 1,3,5,...k 
Fig. 7: The half-bridge VSI. Ideal waveforms for the SPWM
( am = 0.8, fm = 9): (a) carrier and modulating signals;
(b) switch S+ state;(c) switch S− state; (d) ac output voltage;
(e) ac output voltage spectrum; (f) ac output current; (g) dc
current; (h) dc current spectrum; (i) switch S+ current; and
(j) diode D+ current.
for l = 2, 4, 6,…; the amplitude of the ac output
voltage harmonics is a function of the modulation index
am and is independent of the normalized carrier frequency
fm for fm > 9; (d) the harmonics in the dc link current
(due to the modulation) appear at normalized frequencies
p
f centered around the normalized carrier frequency fm
and its multiples, specifically,

1f
p l km   1,2,3,.....l 
(5)
Where 2,4,6,...k 
For 1,3,5,.....l 
And
1,3,5,...k 
l = 2, 4, 6, … Additional important issues are: (a)
for small values of fm ( fm < 21), the carrier signal
v and the signal cv should be synchronized to each
other ( fm integer), which is required to hold the previous
features; if this is not the case, sub harmonics will be present
in the ac output voltage.
The PWM technique allows an ace output voltage
to be generated that tracks a given modulating signal. A
special case is the SPWM technique (the modulating signal
is a sinusoidal) that provides, in the linear region, an ac
output voltage that varies linearly as a function of the
modulation index, and the harmonics are at well-defined
frequencies and amplitudes. These features simplify the
design of filtering components. Unfortunately, the
maximum amplitude of the fundamental ac voltage is iv /2
in this operating mode. Higher voltages are obtained by
using the over modulation region ( am > 1); however, low-
order harmonics appear in the ac output voltage. Very large
values of the modulation index ( am > 3.24) lead to a
totally square ac output voltage that is considered as the
square-wave modulating technique
 Matlab simulink model of five phase two-level
voltage source inverter with PWM technique
Fig. 8: Matlab/simulink model for PWM Method of
five phase induction motor drive
V. RESULTS
Matlab/simulation results of three phase two-level voltage
source inverter and five phase two-level voltage source
Simulation results of for TPTLVSI and FPTLVSI
the operating conditions given below are shown in Fig.7 to
fig.11. Simulation results show output phase voltages, line
voltage currents, gate triggering, load current, harmonics
analysis for five phase two level voltage inverter.
Operating condition:
Simulation time: 0.02 sec
DC Link Voltage Vdc=200 V before running simulation
given in command prompt.
Freq=50 Hz running simulation given in command prompt.
Fig. 9: Matlab/simulation results for output phase voltages
of Three phase two-level voltage source inverter and five
phase two-level voltage source
Fig. 10: Matlab/simulation results for output load currents of
three phase two-level voltage source inverter and five phase
two-level voltage source
Fig.11: Matlab/simulation results for Input signal, carrier
signal and PWM method

Fig. 12: Matlab/simulation results for output voltages
(without filter) of five phase two-level VSI
Fig. 13: Matlab/simulation results for output voltages (with
filter and PWM control scheme) of five phase two-level VSI
Fig.14: Matlab/simulation results for FFT analysis output
voltages (with filter and PWM control scheme) of five phase
two-level VSI
VI. CONCLUSION
A comparison of total harmonic distortion in the output
phase voltages of five-phase voltage source inverter for
different conduction angle is presented. The conduction
angles considered are 180°, 162°, 144°, 126°, and 108°.
Thus two more conduction states are included when
compared to further prove the superiority of control at 120°
conduction mode. It is observed that the lowest THD is
obtained for 120° conduction mode.
Harmonic analysis of output line voltages of one
of the phase of FPTLVSI without any control scheme and
filter is carried out with different firing angle of gating
circuit of FPTLVSI and result is obtained that at 1200
optimal value of THD of line voltage of 27.03.
Harmonic analysis of output line voltages of one of
the phase of FPTLVSI with PWM control scheme and filter
is carried out and result is obtained that THD of of output
line voltages of one of the phase of FPTLVSI is reduced
greatly with value of 3.65.
This paper has reviewed analytical approach for
five phases two level voltage inverter used in application of
induction motor drive.
REFERENCES
[1] E. Levi, R. Bojoi, F. Profumo, H. A. Toliyat, and S.
Williamson, “Multiphase induction motor drives—A
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[2] Grandi, G. Serra, and A. Tani, “General analysis of
multi-phase systems based on space vector approach,” in
Proc. Int. Power Electr. Motion Control Conf. (EPE-
PEMC), Portoroz, Slovenia, 2006, pp. 834– 840.
[3] Y. Zhao and T. A. Lipo, “Space vector PWM control of
dual three-phase induction machine using vector space
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[4] P. S. N. de Silva, J. E. Fletcher, and B. W. Williams,
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[5] D. Dujic, E. Levi,M. Jones, G. Grandi, G. Serra, and A.
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inverters,” in Proc. IEEE Power Electr. Spec. Conf.
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[6] G. Grandi, G. Serra, and A. Tani, “Space vector
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[7] D. Dujic, M. Jones, and E. Levi, “Space-vector PWM for
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Analysis Approach for Five Phase Two-Level Voltage Source Inverter with PWM Technique for Induction Motor Drive

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Analysis Approach for Five Phase Two-Level Voltage Source Inverter with PWM Technique for Induction Motor Drive