Master slave vector controlled double induction motor using unity power factor controlled pwm rectifier

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 02 Issue: 10 | Oct-2013, Available @ http://www.ijret.org 427
MASTER SLAVE VECTOR CONTROLLED DOUBLE INDUCTION
MOTOR USING UNITY POWER FACTOR CONTROLLED PWM
RECTIFIER
G. Hari Krishna1
, V. L. N. Sastry2
1
M. Tech Scholar, 2
Assistant Professor, Electrical and Electronics Engineering, SASI Institute of Technology and
Engineering, Andhra Pradesh, India, harikrish213@gmail.com, sastry@sasi.ac.in
Abstract
In the recent days most of the industries uses Induction motors as the primary loads. In order to meet the total load requirement
multiple motors are used. In this paper two Vector Controlled (VC) Induction Motors and a double closed loop PWM rectifier are
used to explain the operation of Master Slave Configuration. The work mainly concentrates on the operation of a Unity Power factor
Controlled (UPFC) PWM Rectifier as the input source for both the Vector Controlled Induction Motors. This UPFC PWM Rectifier
uses two closed loop pi control algorithms the inner loop controls the current and the outer loop controls the DC voltage. The
proposed model is simulated in Matlab/ Simulink and the results shows good synchronization for two induction motors operated in
master slave configuration.
Keywords: Vector Control, Induction Motor, PWM Rectifier, and Unity Power Factor Control
--------------------------------------------------------------------***------------------------------------------------------------------------
1. INTRODUCTION
In recent years induction motors are widely used in industries
due to theirs advantages such as speed capability, robustness,
cheapness and ease of maintenance. When the induction motor
is operated in oriented control scheme it can compete with dc
motor in high performance applications [1]. Due to the perfect
decoupling control of flux and electromagnetic torque in the
vector control of induction motor, it gains great interest in
many industrial applications.
In this paper one of the motor is operated master and the other
as slave, the speed of the master motor is a reference signal in a
closed loop control system which can control the speed of slave
motor and tract the speed of master.
2. UNITY POWER CONTROL METHOD OF PWM
RECTIFIER
Figure 1 gives the basic structure of PWM rectifier ea (t), eb
(t), ec (t) are the three phase voltages. L is the filter inductance.
R is the equivalent resistance .c is the support capacitance of dc
side. RL IS the load resistance and EL is the load voltage [2].
When the load force voltage is either zero or less than DC
voltage across the capacitor then the rectifier operates in
rectifier mode otherwise in active inverter mode.
L
L
L
Z
Z
z
ea
eb
ec
T1
T4
T6
T5T3
T2
C
Udc
eL
RL
Fig.1 The structure of PWM rectifier
Figure 2 shows the block diagram unity power factor control of
the PWM rectifier. This controller uses double closed loop PI
control, inner PI loop control the three phase input current
method controller by unity power factor control and the output
DC voltage is controlled by outer PI loop [3].

__________________________________________________________________________________________
vdc
iabc
vabc
Anti
aliasing
filter
Abc
To
dqo
Pulses
Triggering
pulse
generator
PI
PI
_+
+_
PI
Iq Ref.=0
+
_
Vdc Ref.
Iq
Id Ref.
Id
Fig.2 The unity power factor control method of PWM rectifier
3. VECTOR CONTROL OF INDUCTION MOTOR
Speed
controll
er
Torque
controller
Flux
controll
er
Space-vector
modulation
3-phase power
stage
Rotor
flux calculation
Forwardclare
transformation
Speed
command
-
-
Speed sensor
pwmc
Line input
Motor flux
command
Ac induction
motor
speed
Forward park
transformation
pwmb
pwma
Inverse park
transformation
isa
isb
isc
-
-
isq
isd
isα
isβ
usα
usβ
usd
usq
urd
Usq lin
Usd lin
Rotor flux
Decoupling
Fig. 3 Block Diagram of Vector controlled Induction Motor
It is the most popular control technique of ac induction motor.
In this technique stator current of the induction machine are
separated into dq co ordinate system. The direct axis (d) is
aligned with the rotor flux space vector .The q-axis component
of the rotor flux space vector is always zero.
rqrp
dt
d
and  0
……..(1)
3.1 Block Diagram of Vector Control
Figure 3 shows basic structure of the vector control AC
induction motor. The procedure for performing vector control
is as follows [4].
 Measuring motor quantities (phase voltages and
current)
 Covert them to 2-phase system (α,β) using Clarke
transformation

__________________________________________________________________________________________
 Calculation of rotor flux space vector magnitude and
position angle
 Transform stator currents to dq system using parks
transformation
 The stator currents isd , isq which will produce flux and
torque respectively are controlled separately
 By using a decoupling block output stator voltage
space vector is calculated
 Transform output stator voltage space vector to dq
system using inverse park transformation
 By using a space vector modulation output three phase
voltages is generated.
3.2 Forward and Inverse Clarke Transformation
Assume a-axis and α axis in same direction
There
)(
2
3
]
2
1
2
1
[
scsbs
scsbss
iiki
iiiki




…. (2)
Where
sai =actual current of the motor phase A [A]
sbi =actual current of the motor phase B [A]
,si =actual current of the motor phase C [A]
For non power invariant Transformation K=2/3
The inverse Clarke Transformation for the value of K=2/3
Is given by
sas ii 
sbsas iii
3
2
3
1

… (3)
ssa ii 
 sssb iii
2
3
2
1

 sssc iii
2
3
2
1

… (4)
3.3 Forward and Inverse Park Transformation
Because the control process is not possible in stator reference
frame these are shifted to dq reference frame
filedsfiledssd iii   sincos 
fliedsfieldssq iii   cossin 
…… (5)
Where
rd
r
fleld


 
sin
rd
r
flied


 
cos
…. . (6)
22
  rrrd 
..…. (7)
Inverse park transformation is given by
fliedsqfliedsds
fliedsqfliedsds
iii
iii




cossin
sincos


….. (8)
3.4 Rotor Flux Model
In AC induction motor vector control magnitude of rotor flux
space vector place a vital role. To obtain rotor magnetic flux
space vector here the process of monitoring rotor speed, stator
voltage. And currents are utilized.
By solving the following equation, rotor flux space vector can
be obtained
   dt
di
TLTu
R
L
dt
d
TT s
smrrrs
s
mr
rs





 1
……. (9)
   dt
di
TLTu
R
L
dt
d
TT
s
smrrrs
s
mr
rs





 1
…… (10)
Where
Ls=self-inductance of the stator [H]
Lr =self-inductance of the rotor [H]
Lm=magnetizing inductance [H]
Rs=Resistance of a stator phase winding [Ohm]
Rr =Resistance of a rotor phase winding [Ohm]
 = Angular Rotor speed [rad. s-1]
pp = Number of motor pole pairs
rT = r
r
R
L
= Rotor Time constant [s]

__________________________________________________________________________________________
r
s
s
L
L
T 
= Stator Time Constant [s]

rs
m
LL
L2
1
Resultant Leakage Constant [-]
3.5 Decoupling Circuit
The Purposes of rotor flux –oriented vector controls, the direct
axis stator current and quadrature axis stator current must be
controlled independently. The stator currents are decoupled
control and stator voltages are not considered. The stator
voltage decoupled and stator current components isd and Isq
are indirectly controlling of terminal voltage of induction
 linear components
lin
sq
lin
sd uu ,
 Decoupling components
decouple
sq
decouple
sd uu ,
The equations are decoupled as follow:
][][
rr
mrd
sqLssdLsdR
decouple
sd
lin
sdsd
tl
l
iki
dt
d
kikuuu

 
………. (11)
][][ rd
r
m
sdlssdlsqr
decouple
sd
lin
sdsq
l
l
iki
dt
d
kikuuu  
……. (12)
Where
r
r
m
SR R
L
L
RK 2
2

……. (13)
r
m
SL
L
L
LK
2

….. (14)
sdLsdR
lin
sd i
dt
d
KiKu 
…… (15)
sqLsqR
lin
sq i
dt
d
KiKu 
…… (16)
The decoupling components
)( rd
rr
m
sqLs
decouple
sd
TL
L
iKu  
…. (17)
)( rd
r
m
sdLs
decouple
sq
L
L
iKu  
….. (18)
3.6. Space Vector Modulation
It can directly transform the stator voltage vectors α, β-
coordinate system to pulse width modulation signals. It is more
valid for transformation from α, β- coordinate system, this
technique are good results. In the basic principle of standard
space vector modulation explained d with the help of power
stage schematic diagram
Ud/2
Ud/2
+
-
-
+
Id0
Sat
Sab
SctSbt
SBb SCbIa
IB
iC
A
O
C
B
UB
UA UC
UR
UL
UIB
UIC
UIA
UL URULUR
UCA
UAB
UVB
UBC
UVC
Fig.4 power stage schematic diagram
Table1 is there are six non-zero vectors UO, U60, U120, U180,
U240, U300 and two zero vectors O000 andO111, defined in α,
β coordination. The combination of ON/OFF states of power
state switches for each voltage vector by the three digital
numbers is parenthesis.
Figure 4 as the eight possible switching states are possible and
given by combinations of the corresponding power switches the
value ONE means upper switch is ON and bottom switches
OFF.
The value ZERO means upper switches are OFF and bottom
switches are ON. Within the result in output line – to – line
voltage, phase voltage, voltage vector
Table1 Switching Patterns and Resulting Instantaneous Line –
to-Line and Phase Voltages
abc Ua Ub Uc Uab Ubc Uca
000 0 0 0 0 0 0
100 2Udc/3 -Udc/3 -Udc/3 Udc 0 -Udc

__________________________________________________________________________________________
110 Udc/3 Udc/3 2Udc/3 0 Udc -Udc
010 -Udc/3 2Udc/3 -Udc/3 -Udc Udc 0
011 2Udc/3 Udc/3 Udc/3 -Udc 0 Udc
001 -Udc/3 -Udc/3 2Udc/3 0 -Udc Udc
101 Udc/3 -2Udc/3 Udc/3 Udc -Udc 0
111 0 0 0 0 0 0
It is a technique and direct bridge between vector control and
PWM.
1. Sector identification.
2. Space voltage vector decomposition into direction of
sector base vector ux, ux±60 .
3. PWM duty cycle calculation
Fig.5 Base Space Vector and Voltage Vector projection
The principle of the SVM
).(... 11100006021],[ OOTUTUTUT XXSPWM  
…… (19)
021 TTTTPWM 
(20)
Where
T0, T1, T2 =Time periods
U s(α,β ) =Space voltage vector
The direction of the sector base vector Ux, Ux±60
XSXPWM UTUT 1. 
.. (21)
602]60[ ..   XXSPWM UTUT
….(22)
PWM
X
SX
T
U
U
T 1
Vector Ux ……… (23)
PWM
X
SX
T
U
U
T
60
2


Vector ux ±60 …… (24)
)( 210 TTTT PWM  …. (25)
4. MASTER SLAVE CONTROL TECHNIQUE
This technique is used in the process of synchronization Double
motors. The main characteristic is that reference speed given to
the master motor produces the corresponding revolving speed
and it will acts as a reference speed of slave motor. Any noise
or the changes occurred in a master motor will reflected and
tracked by the slave motor [5].
VECTOR
CONTROLLER
SVPWM
inverter
MASTER
MOTOR
Vector
controller
SVPWM
inverter
SLAVE
MOTOR
UPFC PWM
rectifier
vdc
w
w
vdc
W*
Fig.6 Block diagram of master slave control technique
The indirect vector control reference speed and load torque
applied to motor shaft can be selected both switch blocks, in
order to either constant value or step function.

__________________________________________________________________________________________
5. MODELING AND SIMULATION RESULTS
Fig.7 Matlab Simulink model for Master Slave Vector controlled Double induction motor using UPF controlled PWM rectifier
The figure 7 represents the basic building model for a Master
Slave vector controlled Double Induction motor fed by a Unity
Power Factor Controlled PWM Rectifier.
Fig.8 Rotor speed response for a master and slave motors with
the constant reference speed
Figure 8 represents the speed response of the master motor and
the slave motor with the constant reference speed of 80 rpm.
Fig.9 Voltage, Current, Rotor speed and Torque for a Master
Motor and Slave motor

__________________________________________________________________________________________
Figure 9 represents the voltage, current, Rotor speed and
Torque for a Master motor and slave motor for the reference
speed changing from 100 rpm to 80 rpm at 1.5 sec
Fig.10 Output voltage, current and dc voltage of Unity Power
Factor Control PWM rectifier
Figure 10 describes output voltage, current and dc voltage for a
Unity Power Factor Control PWM rectifier. Here at time 0.2
sec the current is in phase with the voltage and maintain unity
power factor.
CONCLUSIONS
In this work all the parameters for the master and slave motors
are investigated, the technique is well synchronized for double
induction motor. In industry applications the synchronization of
double induction motors plays a vital role. The master slave
double induction motor technique has faster speed response,
short settling time, robustness, and less over shoot.
ACKNOWLEDGEMENTS
The authors would like to express special gratitude and thank
all the teaching staff of the electrical department in SASI
institute of technology and engineering for their good support.
Also extend their sincere thanks to the Head of the Department
for his moral and constant support in completing this work.
REFERENCES
[1] Hamid M, Metawally B, Annis WR, performance analysis
of pv pumping systems using switched reluctance motor drives
solar energy,19956;56(2):161.
[2] Zhang jinggang, Yang BO, Zeng guang and Tion
Yangyang, A unity power factor control method of PWM
rectifier, power and energy engineering conference (APPEEC),
2012 Asia-pacific, pp 1-4.
[3] Zhang Chongwei, Zhang Xing, “PWM rectifier and its
control” Bijing mechanical industry press, 2003
[4] Jaroslay Lepka, Petr Stekl, 3-phase AC induction motor
vector control using a 56F80x, 56F8100 or56F8300 Device.
[5] Biao YU, Hui ZHU andChi XUE, “Research on adaptive
fuzzy PID synchronous control strategy of double motor”, I.J
Intelligent system and applications, 2011, 5, 28-33.
BIOGRAPHIES
G. Hari Krishna received the B.Tech.
degree in Electrical and Electronics
Engineering from Sai Spurthi Institute of
Engineering and Technology, Sathupally,
Khammam (Dt.), A.P, India, in 2010.
Currently he is pursuing M.Tech. in Power
Electronics from SASI Institute of
Technology and Engineering College, Tadepalligudem, West
Godavari (DT), A.P, India. His interested areas are in the field
of Renewable Energies, Power Converters, and power
electronics.
V.L.N. Sastry completed B.Tech with
specialization of E.E.E in Sasi Institute
of Technology and Engineering in the year
2008. He completed M.Tech in the stream
of Instrumentation and control systems
JNTU Kakinada in the year 2010. He has
been working as an Assistant Professor in
the department of E.E.E in SASI Institute of Technology and
Engineering at Tadepalligudem for last 3 yrs. He is presently a
member of International Association of Engineers (IAENG)
and International Association of Computer Science and
Information Technology (IACSIT). He has various publications
in reputed International Journals on image fusion, Power
Electronics and Power systems. His areas of research include
neural networks and fuzzy control, image fusion, power
electronics.

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Master slave vector controlled double induction motor using unity power factor controlled pwm rectifier