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Anybody knows about the control of BLDC motor using two hall sensors and how to find out the exact mechanical angle between the hall sensors

Ann1
Associate

We know that. when using three hall sensors, the 3 Hall sensors should be spaced across the printed-circuit board (PCB) so that they are 120° electrical degrees apart. From the center of the motor axis, the number of degrees each sensor should be spaced equals 2 / [number of poles] × 120° i.e. for 6 pole motor,if 1 sensor is placed at 0°, 2nd sensor is placed 40° rotated, and 3rd sensor is placed 80° rotated.

Similarly, i have seen a 8 pole BLDC motor with 2 hall sensor . For controlling with 2 hall sensor, what should be the proper placement angle? How is it calculated. . What will be the control logic ? Is it estimating the third hall sensor signal from the existing signals?

1 REPLY 1
cedric H
ST Employee

Hello Ann,

This is an interesting question, I have never encountered such kind of motor. Could you share the motor reference ?

Are you sure that your motor does not have an encoder instead ? encoder requires only two wires.

Thanks

Cedric