Bldc commutation problem (need 6 hall sensors)

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Swap_4342

Joined Jun 3, 2018
5
Hiii, i am working on my axial flux bldc motor project. It has 18 stator poles (each phase consist of 6 poles) and 12 magnets on rotor. Stator to magnet ratio is 1.5. its working consist 6 steps repeatedly to rotate the rotor. according to my search standard bldc motor uses only three sensors to rotate the rotor, but my motor needs 6 sensor to detect these 6 different steps of rotor to commutation. I want to make it work using only 3 sensors
I am using a3144 hall effect sensor that detects only north pole
Commutation sequence and sensors input is in image
Sorry for the bad representative drawing.
Its axial flux bldc motor rotors rotation in image is given in linear direction to understand
 

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MaxHeadRoom

Joined Jul 18, 2013
19,064
If it is a 3ph motor then you should be able to do it with 3 hall sensors.
They can be aligned by back feeding/rotating the motor and 'scope the hall positions for alignment.
Max.
 

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shortbus

Joined Sep 30, 2009
6,987
according to my search standard bldc motor uses only three sensors to rotate the rotor, but my motor needs 6 sensor to detect these 6 different steps of rotor to commutation.
Are you forgetting that it takes the rotor moving 720 degrees of rotation, to make one(360 degrees) electrical rotation? That is what allows the motor to only use 3 hall sensors.
 
Last edited:

MaxHeadRoom

Joined Jul 18, 2013
19,064
Also there is 360 electrical degree's and 360 mechanical, the # of electrical rotations per mechanical is decided by the pole count.
Max.
 
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