International Journal of Electronics Communication and Computer Technology (IJECCT)
Volume 2 Issue 1 (January 2012)
Analysis of Motoring and Generating Operation
Through Vector Control Induction Machine Drive
Hemant Chouhan
Dept. of Electrical & Electronics Engineering
SVITS, Indore, India
chouhan31@gmail.com
Abstract— This paper presents a wide Range of
acceptability of model for different values of load and for
various types and ratings of induction motor. The
uniqueness of the model lies on deviation. Due to changes
in reference step on sudden application the values of
torque and speed varied for machine drive. When any
sudden changes in the speed reference is desired, the speed
and torque waveforms reveal that the time taken in
coming back to their final steady state values is very less
and the motor overcomes the perturbation with negligible
transients. This concept gives the solution for motoring
and generating modes.
Keywords: Induction motor, mathematical model, torque
controller.
I.
INTRODUCTION
The Analysis of Motoring and Generating Operation
Through Vector Control Induction Machine Drive is the most
important concept that are being used in the real world
applications. Speed closed loop control is widely used in
induction motor drive system. In vector control, the AC motor
is equivalent to the DC motor by coordinate transformation.
The decoupling control of the electromagnetic torque can be
completely realized by using vector control [1]. The strategy of
the vector control is also discussed in detail. For the voltage
source inverter, the method of rotor flux orientation and
waveform generation of current-traced SPWM are adopted.
The simulation model of the system is established under
MATLAB according to the vector control model. The vector
control of ac drives [1] has been widely used in high
performance control system. Indirect field oriented control
(IFOC) is one of the most effective vector control of induction
motor due to the simplicity of designing and construction. In
order to obtain the high performance of torque and speed of an
IM drive, the rotor flux and torque [2].
II.
MODELING OF INDUCTION MACHINE
Dinesh Chandra Jai
Dept. of Computer Sc. & Engineering
SVITS, Indore, India
dineshwebsys@gmail.com
analysis is based on a vector representation of current, voltage
and magnetic flux.
The mathematical model of a three-phase, Y-connected,
squirrel-cage induction motor and load is described by
equations in the synchronously rotating reference frame.
TABLE I.
NOME NCLATURE
Ls, Lm, Lr
Stator, mutual, rotor inductance
Rs, Rr
Stator, rotor Resistance
P
no. of Pole
VdS, VqS
d-axis and q-axis component of stator voltage vector
Vs
d-axis and q-axis component of rotor voltage vector Vr
Vdr, Vqr
idS, iqS
iqr
&
idr,
d-axis and q-axis component of stator/rotor current
vector Is
Te, J ,
Exciting torque, moment of inertia
ωe, ωr ωsl
Synchronous, rotor, slip speed
ψds, ψdr
Stator and rotor leakage flux
is
Stator current
Vqs = Rsiqs + Fqs+ (ωe/ ωb )Fds
(1)
Vds = Rsids +1/ωb Fds - (ωe/ ωb )Fqs
(2)
0 = Rriqr +1/ωb Fqr+ (ωe-ωr)/ ωbFdr
(3)
0 = Rridr +1/ωb Fdr -(ωe-ωr)/ ωb Fqr
(4)
Where it assumed that Vqr=Vdr=0 for squirrel cage
induction motor.
Vector control drives seek to dynamically regulate motor
torque as directly and accurately as possible. Speed is regulated
indirectly by providing exactly the torque required to operate
the driven equipment at the desired speed [3]. Vector control
drives use a mathematical model of the motor to dynamically
determine the values of the essential operating and control
parameters. They are called "vector control" drives because this
ISSN:2249-7838
IJ ECCT | www.ijecct.org
47
International Journal of Electronics Communication and Computer Technology (IJECCT)
Volume 2 Issue 1 (January 2012)
III. TORQUE AND FLUX CONTROLLER
Figure 3.
Figure 1.
Block Diagram of Vector Control
=ω
(5)
= ωb
(6)
= ωb
(7)
= ωb
(8)
Vector controlled drive
The physical principle of vector control can be
understood more clearly with the help of d e- qe circuit. Since
currents ids and iqs are being controlled, ideally stator side
Thevenin’s impedance is infinity, that is, the stator side
parameter and EMFs are of no consequence. With ψqr=0 under
all condition, EMF ωslψqr=0 in the de circuit. This indicates
that at steady state, current ids flow through magnetizing
branch only to establish the rotor flux ψr but transiently, the
current will be shared by rotor circuit also an time constant
can be easily seen as Lr/Rr. in the qe circuit, when torque
controlled by iqs, EMF ωsl ψdr in the rotor circuit is modified
instantly because ωslψdr=LmRr iqs/Lr [5, 6, 7].
Torque equation is
Te =
(9)
is=
(11)
The speed ωr can’t be normally treated as a constant. It can
be related to the torques as [1-2]:
Te = T L + J
=TL + J
(10)
Figure 4. Torque controller
Figure 2. Dynamic or d-q equivalent circuit diagram of induction motor
Figure 5.
In the vector control, the AC motor can be equivalent to the
DC motor under the principle of generating the same magneto
motive force. Firstly, the model of the three-phase
asynchronous motor is converted into an equivalent model
based on ds-qs static coordinate. Secondly, by using rotating
coordinate transformation, the ds-qs model is converted into an
equivalent mode under dr- qr, coordinate, which is in
synchronously with the rotating magnetic field [1, 4].
ISSN:2249-7838
Flux controller
IV. MOTORING AND GENERATING OPERATION
This Vector control drive operates in motoring and
generating mode due to step load change. Due to negative
torque action drive speed suddenly change in generating mode
speed is higher than normal speed [8, 9]. This control system
will calculate the speed and torque of the motor and compare
them against preset values. A three-phase inverter will be used
to alter the stator currents to enable the speed to be changed.
IJ ECCT | www.ijecct.org
48
International Journal of Electronics Communication and Computer Technology (IJECCT)
Volume 2 Issue 1 (January 2012)
The system will use Field Orientated Control principles to
adjust the motors speed and torque [10-12]. A block Diagram
of the proposed control system is shown in fig. (1).
Figure 8.
Torque-Speed response at 10 n-m and -10 n-m
a) At 10 Hz supply frequency, speed is 300 RPM, but at
60 Hz supply frequency, speed is 1800RPM.
Figure 6.
b)
Vector Control Model
V. SIMULINK RESULT
A. Vector control in motoring mode:
1) When load torque is changed, speed is constant (10
Hz).
Motor torque is varies from (10) n-m to (-10) n-m
c) Step is change from 0.3sec (10 n-m), at this moment
some transient comes into picture, after that transient torque
is steady state at (-10 n-m.)
d) At above the synchronous speed (1500 RPM)
induction motor will operated as an induction generator, For
this operating mode, slip is negative[13,14].
VI. CONCLUSION
The proposed technique is simple but provides a high
performance torque control solution. The proposed scheme
can be used in applications where there is no need for speed
control or simply to insure the in- dependency of rotor
resistance. Finally, with the help of model to simulate both
induction motors and generator has been shown so that no
requirement for different models for different application.
REFERENCES
[1]
Figure 7.
Torque-Speed response at 5 n-m
[2]
a) At supply frequency 10 Hz speed is 300RPM.
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d)
R.P.M.
[3]
[4]
Motor torque is varies but speed is constant at 300
[5]
B. Vector control in generating mode:
1)
Hz)
System response at above the synchronous speed (60
[6]
[7]
[8]
ISSN:2249-7838
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International Journal of Electronics Communication and Computer Technology (IJECCT)
Volume 2 Issue 1 (January 2012)
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