Does the sytem sees any different between coil beeing face and static to the right magnet or not and still static? or does he sees any difference only when moving BEMF (like the sensorless brushless motor)?
I recognize most of those words, but not in that order. Sorry.
Ok sorry, I'll try again.
If you supply a coil with current, the motor will spin since the fields of the coil and the magnet are face to face. I call this position: "coil beeing face [...] to the right magnet".
Now you block the shaft of the motor. If you supply a coil with current, the motor will not spin since the fields of the coil and the magnet are face to face. I called this position:"[...] or not"
In both these cases, nothing turns, then there is no evolution of of the magnetical field, then no evolution of the current in the coil, then unuseful... this is how position is known in brushless motor, without sensors.
My question is: Even if there is no difference in coils, is there any difference anywhere that could be used.
Idea n°1 but which needed added hardware:
Rotary encoder: quite expensive If I want to be almost as precise as the stepper
Idea n°2 but which needed added hardware
Hall effect sensor: Because I don't need an absolute position but a relative one. Do any stepper motor have build-in hall effect sensors ? (need to get at least 2 to be as precise as stepper)
PS: I assumed the system was static beacause of the slow rotation speed of hand moving.
I hope this will be more understandable than previous post.