Currently I am working on a BLDC controller for 2kW hub BLDC motor of chinese origin. It does have 63 stator slots and 56 poles. I tried almost all standard BLDC switching sequences and some other sequences made by my own intuition. Finally I could run it in forward direction with the following algorithm. There are no missing steps in the rotation.

Hc Hb Ha                                  --Ha : hall sensor for A phase
0  0   1  : AC                            --AC => +ve on phase A and -ve on phase B
0  1   0  : BA
0  1   1  : BC
1  0   0  : CB
1  0   1  : AB
1  1   0  : CA

I couldn't find an algorithm to run it in the reverse direction. I tried reversing the above sequence. It didn't reverse the direction of rotation, rather the motor rotated in forward direction with missing pulses (I could hear a noise when there is one or more pulses are missing). What should be the right algorithm to turn the motor in opposite directtion?

  • \$\begingroup\$ This question would be more clear if you show a wiring diagram. If you have the facilities to do it, spinning the motor while capturing the Hall outputs and the coil-coil voltage on an oscilloscope should make everything clear. \$\endgroup\$
    – TimWescott
    Mar 31, 2021 at 17:50
  • \$\begingroup\$ And I think there's only two common mappings from hall outputs to coil phases -- but I can't remember them!! \$\endgroup\$
    – TimWescott
    Mar 31, 2021 at 17:51
  • \$\begingroup\$ What have you searched so far. It is a trivial problem that is extinct. \$\endgroup\$ Mar 31, 2021 at 17:53

1 Answer 1


From FAQ: What are Hall effect sensors and what is their role in dc motors?:

enter image description here

Hall should only change a bit at a time.

H3 to H1 = 101 001 011 010 110 100 = 5 1 3 2 6 4 = VU WU WV UV UW VW = BA CA CB AB AC BC

H? Hb H?                     --Ha : hall sensor for A phase
1  0   1  : BA               --BA => +ve on phase B and -ve on phase A
0  0   1  : CA
0  1   1  : CB
0  1   0  : AB
1  1   0  : AC
1  0   0  : BC

You have the right states, but I believe they are not in the correct order. As in Ha, Hb and Hc order is wrong. Ha and Hc need to be reversed.

You go CA to AC. That's high on C to low on C, coupled with low on A to high on A. Thet does not make sense.


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