Leafmotor

Some very strange problem with 48V 5000W bldc motor. Purchased six motors half a year ago, for EV project. We managed to get to the actual testing with your motors only now.

When started our tests, we faced very strange problem.

Need help and suggestion on what the reason of problem can be.
We have or own BLDC controller, with three half-bridge, PWM for low
gates and block commutation for high gates. Everything works great,
but motor does not start in two particular positions of rotor.

If refer to the wiring diagram, motor does not start when try to
rotate it clockwise (if I look into shaft) when:

1) Hall sensor with yellow wire is activated, others passive
2) Both hall sensors with yellow and green wires are activated, blue
is passive.

When try to run it counterclockwise it doesn’t start in two other
positions when:

1) Hall sensor with blue wire is activated, others passive
2) Both hall sensors with blue and green wires are activated, yellow
is passive.

Please note that in both cases the positions where motor doesn’t start
are consequent.

Motor starts perfectly in all other positions of Halls. If motor
started in some other position, it rotates without problems. I think
it simply passes the problem angles due to inertia it has.

I checked, double and triple checked my truth table and it is okay.
It works great on some other BLDC motors I have.

Then I thought that this particular motor has problems in its wrings
inside and tried other motors I purchased from you. All six motors
show the same problem, in the same positions.

So I have two possibilities now:

1) There are some “dead” zones inside motor which I’m not aware of. I
think this is an issue. If so, please let me know how to overcome it.

2) Something wrong with my controller. But this is unlikely. Firstly, it
works with other BLDC motors without problems. Secondly, your motor
doesn’t start in two consequent positions of rotor. If algorithm is
wrong, then it will fail on some opposite positions, not consequent.

Please, let me your thoughts on this problem, as I’m starting to think
that there is some secret in motors that I don’t understand!

Any help will be greatly appreciated.

And please note that letting aside this above mentioned problem, your
motors are pure gold and we are going to order some good amount for
our EV factory in next months, if we settle this very problem I talk
of.