3 phase Unipolar Stepper drivers; any ideas??



  • Has anybody here ever encountered a 3-phase unipolar motor before? I need to build a driver for these and I'm looking for inspiration.

    IMG_20191024_133152.jpg

    They come from some old Disk Cartridge unit I dismantled as a teenager; I want to use them as the Z axis on a large format lasercutter. Mounted vertically and using the shaft as a structural member as well as for movement. But have hit a problem:

    IMG_20191024_133631.jpg

    They only have 24 steps/rev, but impressive torque. I'd seen those wires and assumed they were 2 phase bi-polar, but 5 mins with a multimeter wiped the smile from my face. There is no real information about this type of winding online that I could find.
    But; they are still good for their function, especially if I can microstep them.

    My current best idea is a Arduino328P (uno) based system using 3pwm channels per motor and a NPN mosfet/darlington on each coil. Maybe use a I2C client lib for control from the ESP, but first goal simply to serial control and move them with a decent accuracy.

    Has anybody here ever built their own stepper drivers from scratch? any hints? This is a long-term project so I'm just gathering ideas for now.
    IMG_20191024_133133.jpg

    (PS: This is a duplicate of a question I asked on a CNC oriented forum, but I thought it worth asking here too.)
    (PPS: Imperial; 2'' bodies and 3/16'' shafts, they practically play the star-spangled banner as they rotate. Very well built.)


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