With BLDC motors and open loop commutation, you can't immediately commutate at the RPM you desire. If your stator field's RPM is far greater than your rotor's RPM, then the stator will never "catch up" to the rotor rpm. We would call this "slip" in the AC motor world.

But this is the BLDC world, and things are different. We must commutate synchronously, or the system will not work.

The solution here is to ramp or soft-start the motor. Don't immediately commutate your stator at 5000 rpm (for example). You must first ramp the rpm from 0 up to 5000 rpm in some interval that works well for your system. This gives the rotor a chance to "catch up" to the stator field before switching it again.

An obvious symptom of an out of phase commutation is a buzzing sound. I wonder if you hear any noise when you try to run your motor or not?

With BLDC motors and open loop commutation, you can't immediately commutate at the RPM you desire. If your stator field's RPM is far greater than your rotor's RPM, then the rotor will never "catch up" to the stator rpm. We would call this "slip" in the AC motor world.

But this is the BLDC world, and things are different. We must commutate synchronously, or the system will not work.

The solution here is to ramp or soft-start the motor. Don't immediately commutate your stator at 5000 rpm (for example). You must first ramp the rpm from 0 up to 5000 rpm in some interval that works well for your system. This gives the rotor a chance to "catch up" to the stator field before switching it again.

An obvious symptom of an out of phase commutation is a buzzing sound. I wonder if you hear any noise when you try to run your motor or not?