Morgan Olsson wrote:

> >> Here is a search result URL for the info, not sure which link contains the
> >> thesis, but the few things I have picked out like the controller chip from
> >> motorola (MC330033) looks good.
> >>
> >> http://www.google.com/u/uqitee?q=motor%20controller
>
> Interesting thingy :)
>
> One thing i noted, was that is is possible to configure for 2-phase motors.
>
> One customer have need for low rpm high torque low inertia compact driver, so a conventional 200 step/rev stepper and this unit.
>
> Now... problem is mounting the hall sensors that close and inside... impossible!
> But... maybe an optical decoder on the shaft... if i can get hands on one with suitable resolution and phase angle.


A 200 step motor has 50 magnetic poles so a quadrature
encoder with 25, 50 or 100 slots would do it.
The hard part would be adjusting the angle of the encoder
disc relative to pole angle, this is critical for decent
power/efficiency if you are going to use it for simple
commutation. With only 1.8 degrees for a quarter pole,
the encoder would have to be adjusted *finely* within a
short range within that 1.8 degrees. :o)

Surely using a micro to control stepper motor current and
phasing is going to give better control of speed and
probably better torque than commutation anyway??
-Roman

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