You can replace your control electronics with three opamps, each wired
with gain x 1000 differential input, across the Hall sensor outputs. This
is a tried and working scheme.

To determine the Hall phases etc, you can use the following method:

- supply the hall sensors.
- supply one phase of the motor (I assume it is wye) with dc from a
current limited psu.
The motor will turn and lock on that phase.
- measure Hall outputs and fill in into a table on paper or computer
- feed the next phase. Continue for each phase.

- finally, connect the dvm across one Hall sensor (your choice), and turn
the motor by hand against the energized winding to make sure that the
maximum voltage occurs at the magnetic detent caused by a phase. There are
freak motors that have Hall sensors offset for high speed operation. I
hope that you do not have one of those.

The resulting table will tell you more than you want to know about the
needed controller.

To reduce the current with your simple controller, you need to apply
'magic sine' technology. In this case you should replace the opamp with
two comparators (one for H one for L in each half H bridge) so no current
is driven into a winding when a Hall sensor is not full on (either fwd or
bwd). This may impair self starting capability so you will need to play
with the comparator levels etc. IC brushless controllers do almost
exactly this and more.

Peter

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