ABSTRACT:
Now-a-days ,sensor less speed control modes of operation are becoming
standard solutions in the area of electric drives. The technological
developments require a compact and efficient drive to meet the challenging
strategies in operation of the system. This paper provides a speed sensor less
control of an Induction motor with a model based adaptive controller with
stator current vectors. The purpose of the proposed control scheme is to create
an algorithm that will make it possible to control induction motors without
sensors. A closed loop estimation of the system with robustness against parameter
variation is used for the control approach. A Model Reference Adaptive System
(MRAS) is one of the major approaches used for adaptive control. The MRAS
provides relatively easy implementation with a higher speed adaptation algorithm.
MRAS proposed in this paper owing to its low complexity and less computational
effort proposes a feasible methodology to control the speed of an Induction
Motor (1M) drive without using speed sensors. Simulations results validate the
effectiveness of this technique
KEYWORDS:
1. Indirect
Field oriented control,
2. induction
motor drive
3. sensor less
speed estimation,
4. Model
Reference Adaptive control.
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
SIMULINK BLOCK DIAGRAM:
Fig2 Overall
Simulink model of sensor less control of induction motor using MRAS with PI
controller.
EXPECTED SIMULATION RESULTS:
Fig.3 MRAS speed response (w"r=
1500 rpm and no-load) speed
Fig4MRAS response with step changes in reference
Fig. 5. MRAS speed
response(w"r=1500 rpm and load of 3 Nm).
Fig.6. MRAS speed response with a load of 3Nm
Fig7.
Response of MRAS and Conventional Controller.
CONCLUSION:
The model based control scheme is basically an adaptive
control mechanism. The reference model of the
proposed system consists of the response to be obtained for the input
conditions. The adaptive mechanism continuously monitors the adaptable
parameter (speed in this case). The adaptable parameter is continuously
subjected to changes based on its deviation obtained by comparing it with the
response of the reference model. The speed estimation algorithm in MRAS is computationally less intensive.
MRAS is a relatively simple algorithm and hence
less sophisticated processing can be
employed. MRAS strategy is more robust than
the conventional one. This makes it better
suited if the drive is to be operated in hostile environments. Owing to less sophisticated processing requirements, MRAS technique costs cheaper and hence
overall cost of the drive is reduced. With lower
cost and greater reliability without
mounting problems, the sensor less vector
control schemes have made remarkable developments
in electric drive technology. Due to lesser rise
time taken by MRAS, this method gives faster steady state response and this scheme has better reliability
than the conventional scheme.
REFERENCES:
[I] Teresa Orlowska - Kowalska and Mateusz Dybkowski ,
"Stator Current based MRAS estimator for a wide range speed Sensor less
induction motor drives", IEEE Transactions on Industrial Electronics
vo1.51, No. 4, April 2010, pp. 1296 - 1308.
[2] B. K. Bose, Power Electronics and Motor Drives, Pearson
Education Inc., Delhi, India, 2003.
[3] M. Rodic and K. Jezernik, "Speed-sensor less
sliding-mode torque control of induction motor," IEEE Transactions on
Industrial Electronics, vol. 49, no. I,
pp. 87-95, February 2002.
[4] L. Harnefors, M. Jansson, R. Ottersten and K. Pietilainen,
"Unified sensor less vector control of synchronous and induction
motors," IEEE Transactions on Industrial Electronics, vol. 50, no. 1, pp.
153-160, February 2003.
[5] M. Comanescu and L. Xu, "An improved flux observer
based on PLL frequency estimator for sensor less vector control of induction
motors ," IEEE Transactions on Industrial Electronics, vol. 53, no.1, pp.
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