A. Ravi Kumar Reddy et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 3, Issue 6, Nov-Dec 2013, pp.989-993
RESEARCH ARTICLE
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OPEN ACCESS
Direct Torque Control of IM Drive for Speed Regulator Using
Adaptive Controller
A. Ravi Kumar Reddy1, A.Mallikarjuna Prasad2, S. Thirumalaiah3
1
Post Graduate Student, SJCET, Yerrakota, Yemmiganur.
Associate Professor, SJCET, Yerrakota, Yemmiganur.
3
Associate Professor, SJCET, Yerrakota, Yemmiganur.
2
ABSTRACT
This paper presents a new improved method of direct torque control (DTC) of induction motor drive (IMD) for
speed regulator (SR) by using an adaptive controller method .The method of controlling speed of induction
motor based on DTC method by using adaptive controller. The Direct torque control of induction motor using
adaptive controller method is one of the effective method strategies of controlling the torque and flux ripples.
The inverter reference voltage signal is obtained based on input-output feedback signal controller. Designing of
DTC-SVM system and one of the new Method for controlling speed of motor by adaptive controller is given.
Adaptive controller techniques applied to achieve better performances of flux, torque control and speed
controlling of induction motor. The simulation results with low torque, stator flux and speed control with the
Adaptive controller technique in DTC using MATLAB/SIMULINK..
Index Terms: Adaptive stator flux observer, IMD, Space Vector Modulation (SVM), THD, DTC, Stator Flux
Observer, Torque Ripples.
I.
INTRODUCTION
Direct Torque Control (DTC), Pioneered In
The 80's by takahashietal and depenbrock ,Is better
performance induction Motor Drive Scheme That
enables Independent Control Of The Torque And
Flux. Compare To Other High Performance Drive
Schemes Such As The Field Oriented Control (FOC),
DTC Is Relatively Simpler To Implement And Only
Requires The Stator Resistance Information While
Maintaining Similar If Not Better Performance. DTC
Also Offers The Fastest Motor Dynamic Response As
It Changes The Inverter Switching States Directly To
Control The Flux And Torque Without The Need Of
A Modulator. Direct Torque Control (DTC)
Abandons The Stator Current Control Philosophy,
Characteristic Of Field oriented Control (FOC) And
Achieves Torque And Flux Controlling By Modifying
The Stator Voltage With Respective With The Torque
And Flux Errors. So Error Can Essay To Find And
Rectify. DTC Is characterized By Fast Dynamic
Response, Simple Structure And Stronger Robustness
In The Face Of Parameters Uncertainties And
Perturbations. One Of The Disadvantages Of Direct
Torque Control (DTC)Is better Torque Ripple. So
Many Techniques Have Been Introduced To Reduce
the Torque Ripple. One Of Them Is Duty Ratio
Control Method.
In duty ratio Control, Selected Output
Voltage Vectors Is Applied portion of sampling
period, and then zero voltage vector is applied for rest
of the period.
Direct torque control based on space vector
modulation (DTC-SVM) preserve DTC transient
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merits, furthermore, produce improve quality steadystate performance in a wide speed range. At each
cycle period, SVM method is used to obtain the
reference voltage space vector to exactly compensate
the flux and torque errors. The torque ripple of DTCSVM in speed controlling is also better than previous
method. In this paper, we are introducing a new
method direct torque control (DTC) of induction
motor drive (IMD) for speed regulator (SR) by using
an adaptive controller method. SVM-DTC technique
with PI controller for induction machine drives is
developed. Further, controlling of speed adaptive
controller the stator flux observer is designed for a
speed sensor less DTC-SVM system and a speedadaptive law is given. The observer gain matrix,
which is obtained by solving linear matrix inequality,
can improve the robustness of the adaptive observer
gain. The simulation results with low torque, stator
flux and speed control with the Adaptive controller
technique in DTC using MATLAB/SIMULINK.
Figure1. classification of induction motor control
methods
989 | P a g e
A. Ravi Kumar Reddy et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 3, Issue 6, Nov-Dec 2013, pp.989-993
II.
DIRECT TORQUE CONTROL AND
INDUCTION MOTOR DYNAMICS
Fig.1 shows, The typical Direct Torque
Control (DTC) method applied to a three phase
induction motor. From the motor stator resistance R5,
the inverter switching state and the sensed stator
current, the stator flux phasor followed by the
machine torque T, are estimated. The flux and torque
estimator are compared with the reference values, and
the differences are fed into hysteresis comparators.
From Table 1 the appropriate inverter switching state
are applied to the IM drive. The selection depended
on the output obtained by an hysteresis comparators,
dte and dfs, and the sector in which
currently
resides. The inverter switching state that produces the
corresponding voltage vector is shown in the
respective.
Since direct torque control selects the
inverter switching state directly without the need of a
modulator, it produces the fastest torque response
compared to other high performance induction motor
drive schemes. In fact, the torque response is at its
natural limits. Torque response cannot be any faster.
since the torque response is very faster than the
mechanical dynamics. Therefore the dynamics of the
DTC controller and the motor torque production stage
are ignored. Moreover, the ignore dynamics can be
treated as disturbances which the proposed adaptive
controller is capable of counteracting. The torquespeed estimated by mechanical dynamics is
adequately characterised by the equations
(1)
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Figure 3 shows diagram of a typical PI speed
controlled DTC induction motor with the simplified
dynamics. Using PI controller, the kp and ki gains
need to be tuned whenever motor parameter changes
in order to maintain the desired response, for example
when connected load and total system inertia change.
III.
DIRECT TORQUE
CONTROLLERSPACE VECTOR
MODULATION
TECHNIQUE
The DTC-SVM METHOD is developed
based on the Induction motor torque and the stator
flux modules as the system outputs is shown in fig.4
Figure.4 Block Diagram shows the DTC-SVM
method
Te is the electromagnetic torque, TL is the load
torque, J is the combined inertia of the motor and
load, and D is damping constant that represents
energy loss due to viscous friction
Table 1 Voltage Vector Selection
Figure2 Schematic circuit of the DTC method
Figure.3 PI speed controlled direct torque controlled
induction motor.
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990 | P a g e
A. Ravi Kumar Reddy et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 3, Issue 6, Nov-Dec 2013, pp.989-993
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A aresplit in two parts; one corresponding to
nominal or constant operation and the second
unknown behavior.Rs and Rr are nominal value
stator resistance and rotor resistance,the stator
resistance and rotor resistance uncertainties,
respectively.
The state observer, which estimates the
state current and the stator flux together, is given by
the following equation.
Figure 5.Control of Voltage space vector in six
sectors of flux plane.
IV.
In order to derive the adaptive scheme,
Lyapunov theorem is utilized. Now, let us define the
following Lyapunov function:
DTC-SVM
TECHNIQUE WITH
PI CONTROLLER
PI control is one of the earlier control
strategies. It is applied to the D-axis and Q-axis rotor
flux of the Induction motor obtained from the IM
model equation. This improvement can greatly reduce
the torque ripple. The Block diagram of DTC-SVM
with PI controller is shown in fig.6.
VI.
SIMULATIONS
To verify the DVC with adaptive controller,
we are using PI controller and with adaptive stator
flux observer simulations are performed in this
section. The block diagram of the proposed system is
shown in Fig. 4. The parameters of the induction
motor used in simulation results shown below. The
speed and torque response curves of conventional
DTC and proposed DTC-adaptive controller.
Figure.6. DTC-SVM with PI controller
V.
DTC- ADAPTIVE
CONTROLLER
Using the IM model of (1–4), the speed
adaptive stator flux observer is introduced the
uncertain parameters in matrix.
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The SIMULINK model of DTC of induction
motor drive for speed regulator using conventional
Adaptive controller scheme with torque and flux
control for induction machine is shown in Figure 7
below. According to the control schematic, this
technique uses only dc link voltage and current
measurements to generate estimate of flux and torque
response. The drive is operate under torque control
and is very similar to a constant V/Hz drive in terms
of power components and sensors used. Finally, this
strategy supposes to be a good compromise between
high performance field-oriented drives and low
performance V/Hz drives.
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A. Ravi Kumar Reddy et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 3, Issue 6, Nov-Dec 2013, pp.989-993
www.ijera.com
figure(e)have X-Axis On Time(Sec) And Y-Axis On
Stator Flux
VII.
Figure 7 Simulink Diagram Of Adaptive Controller
Simulation Results Of Adaptive Controller
figure(a)) have X-Axis On Time(Sec) And Y-Axis On
Rotor speed
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CONCLUSION
This paper presented a new method of direct
torque control (DTC) of induction motor drive (IMD)
for speed regulator (SR) by using an adaptive
controller technique. The method of controlling speed
of induction motor based on DTC method by using
adaptive controller. The Direct torque control of
induction motor using adaptive controller method is
one of the effective method strategies of controlling
the torque and flux ripples is essay. Adaptive
controller techniques achieving better performances
of flux, torque control and speed controlling of
induction motor compare to previous methods. The
simulation results with low torque, stator flux and
speed control with the Adaptive controller technique
in DTC using MATLAB/SIMULINK.
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A. Ravi Kumar Reddy et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 3, Issue 6, Nov-Dec 2013, pp.989-993
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research scholar inJNTU, Anantapur. He is working
in the area of power system quality control with
application of power electronics.
A. RAVI KUMAR REDDY has obtained
his B.Tech from JNTU, Hyderabad in the
year 2010. He is presently pursuing
M.Tech. from JNTU, Ananthapur in
Power Electronics and Electrical Drives. His research
interests are power converters, FACTS, high power
electronics applications.
A.MALLIKARJUNA PRASAD has
obtained his B.E from MADRAS
University in the year 2001. He has
obtained his M.E from Sathyabama
University in the year 2004. He has 11 years of
teaching experience. Presently he is a research scholar
in JNTU, KAKINADA. He is working in the area of
high power density dc-dc converters.
S.THIRUMALAIAH has obtained his
B.TECH from S.K University in the year
2002. He has obtained his M.Tech from
J.N.TU Hyderabad in the year 2008. He
has 6 years of teaching experience. Presently he is a
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