ABSTRACT:
This paper describes a position sensorless operation
of permanent magnet brushless direct current (BLDC) motor. The position
sensorless BLDC drive proposed, in this paper, is based on detection of back
electromotive force (back EMF) zero crossing from the terminal voltages. The
proposed method relies on a difference of line voltages measured at the
terminals of the motor. It is shown, in the paper, that this difference of line
voltages provides an amplified version of an appropriate back EMF at its zero
crossings. The commutation signals are obtained without the motor neutral voltage.
The effectiveness of the proposed method is demonstrated through simulation and
experimental results.
KEYWORDS:
1. Back electromotive force (EMF) detection
2. Brushless dc (BLDC) motor
3. Sensorless control
4. Zero crossing.
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.
1. Block diagram of the experimental setup
EXPECTED SIMULATION RESULTS:
Fig.
2. Phase current and speed waveform on no-load (experimental).
Fig.
3. Phase current and speed waveform on load (experimental).
Fig.
4. Phase current and speed waveform during loading transient (experimental).
Fig.
5. Phase current, virtual Hall, and real Hall sensor signal for 50% duty ratio
PWM switching.
CONCLUSION
A
simple technique to detect back EMF zero crossings for a BLDC motor using the
line voltages is proposed. It is shown that the method provides an amplified
version of the back EMF. Only three motor terminal voltages need to be measured
thus eliminating the need for motor neutral voltage. Running the machine in
sensorless mode is then proposed, in this paper, making use of the novel
zero-crossing detection algorithm. While starting relies on triggering devices
at the zero crossings detected using the proposed algorithm, continuous running
is achieved by realizing the correct commutation instants 30◦ delay from the zero
crossings. The motor is found to start smoothly and run sensorless even with
load and load transients. Simulation and experimental results are shown which
validate the suitability of the proposed method.
REFERENCES
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[2] J. Shao, D. Nolan,M. Teissier, and D. Swanson,
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[3] T.-H.
Kim and M. Ehsani, “Sensorless control of BLDC motors from near-zero to high
speeds,” IEEE Trans. Power Electron., vol. 19, no. 6, pp. 1635–1645,
Nov. 2004.
[4] S.
Ogasawara and H. Akagi, “An approach to position sensorless drive for
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[5] R.
C. Becerra, T. M. Jahns, and M. Ehsani, “Four-quadrant sensorless brushless ECM
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