SENSOR & SENSORLESS BASED ELECTRONIC
COMMUTATION FOR BLDC MOTOR
ABSTRACT
A brushless DC motor is a permanent magnet electric motor which is driven by direct
current and it accomplishes electronically controlled commutation system instead of a
mechanically commutation system. The brushless design helps in reducing friction
losses, lesser maintenance, and longer lifespan.Due to the electronic commutation,
precise control, higher efficiency, and smoother operation is obtained BLDC motor's
commutation can be done using either sensor-based or sensor-less control methods.
In-order to know when to energise the stator, the position of rotor is to be known.Sensor
based control like Hall effect based, encoder and resolver are used to know the rotor
position. Sensor based methods increases the cost of the system & need for
maintenance.Sensor-less method like Back EMF sensing, Initial Position Detection are
used which can reduce the component cost.Additionally, it reduces the wiring
complexity and Electro Magnetic Interference.
When the rotor rotates, back EMF is induced.The amplitude and shape of the
back EMF waveform depend on the position of the rotor. By measuring the back EMF,
we can infer the rotor position.During each commutation step, the voltage across the
inactive winding is measured. This voltage corresponds to the back EMF of the motor.
The back EMF waveform is then processed to determine the zero-crossing points, which
occur when the back EMF voltage crosses zero. These zero-crossings help in identifying
the rotor position.
REFERENCES
[1] D. Mohanraj et al., "A Review of BLDC Motor: State of Art, Advanced Control Techniques,
and Applications," in IEEE Access, vol. 10, pp. 54833-54869, 2022
[2] G. Mihalache et al., " Implementation of BLDC Motor Driver with Hall Sensor Feedback,"
2018 International Conference and Exposition on Electrical And Power Engineering (EPE),
Iasi, Romania, 2018, pp. 0624-0629
[3] W. Li et al., "A Sensorless Control Method for Low-voltage and High-current BLDC Based
on Back-EMF," 2023 IEEE 6th International Electrical and Energy Conference (CIEEC),
Hefei, China, 2023, pp. 1293-1297
[4] H. Khambhadiya et al., "Sensorless Control Method of 3-Phase BLDC Motor Through
Back-EMF Observer," 2021 International Conference on Advances in Electrical, Computing,
Communication and Sustainable Technologies (ICAECT), Bhilai, India, 2021, pp. 1-5
ASHWIN UNNI
TCR20EE032