ABSTRACT:
In this paper,
a novel motor control method is proposed to improve the performance of
sensorless drive of BLDC motors. In the terminal voltage sensing method, which
is a great portion of sensorless control, a precise rotor position cannot be
obtained when excessive input is applied to the drive during synchronous
operation mode. Especially in the transient state, the response characteristic
decreases. To cope with this problem, the unknown input (back-EMF) is modelled
as the additional state of system in this paper. Taking into account the disturbance
adopted by the back-EMF, the observer can be obtained by an equation of the
augmented system. An algorithm to detect the back-EMF of a BLDC motor using the
state observer is constructed. As a result, a novel sensorless drive of BLDC
motors that can strictly estimate rotor position and speed is proposed.
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.
1. Block diagram of BLDC motor drive.
EXPECTED SIMULATION RESULTS:
Fig.
2. Speed response for the start and transient state. (a) In the proposed
sensorless scheme. (b) In the conventional scheme use sensor.
Fig.
3. Simulation results of the proposed sensorless scheme at 2000 (rpm). (a)
Rotor speed. (b) Rotor position. (c) Phase current. (d) Line-to-line back-EMF.
(e) Commutation function. (f) Commutation signal.
Fig.
4. Simulation results of the proposed sensorless scheme at 100 (rpm). (a) Rotor
speed. (b) Rotor position. (c) Phase current. (d) Line-to-line back-EMF. (e)
Commutation function. (f) Commutation signal.
CONCLUSION:
In this paper, the unknown input
(back-EMF) is modeled as the additional state of system. Considering
disturbance that is adopted by back-EMF, the observer can be obtained effectively
using the equation of augmented system and estimating back-EMF. As a result, an
effective algorithm to estimate rotor position and speed of motor using the
state observer is proposed. Use of sensorless control method can remove problem
on manufacture that is happened in circuit to detect rotor position and speed.
Moreover the production of inexpensive motor controller may be possible because
the additional circuit such as encoder is not necessity. In cases using the
proposed sensorless control method, the start-up performance has an almost
analogous transient state characteristic after forced alignment, compared with
the conventional method. This method also provides useful motor control because
it is possible to analyze about transient state as well as steady state unlike
various sensorless control methods that have been recently proposed. In
addition, it can be easily applied in industry applications requiring the
low-cost style drive of BLDC motor because actual realization is very simple.
REFERENCES:
[l] T. J. E Miller, “Brushless
Permanent-Magnet and Reluctance Motor Drives,” Clarendon Press, Oxford 1989.
[2] S. Ogasawara and H. Akagi, “An
Approach to Position Sensorless Drive for Brushless DC Motors,” IEEE Trans.
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[3] J. C. Moreira, “Indirect Sensing for
Rotor Flux Position of Permanent Magnet AC Motors Operating Over a Wide Speed
Range,” IEEE Trans. Ind. Appl., vol. 32, no. 6, pp. 1392-1401, Nov./Dec.
1996.
[4] H. R. Andersen and J. K. Pedersen,
“Sensorless ELBERFELD Control of Brushless DC Motors for Energy-Optimized
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[5] Hyeong-Gee Yee, Chang-Seok Hong,
Ji-Yoon Yoo, Hyeon-Gil Jang, Yeong-Don Bae and Yoon-Seo Park, “Sensorless Drive
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