OK, I think I understand the “Each phase draws 1.7 A at 2.8 V”. The coils were tested at 2.8V. At that voltage, the coil drew 1.7A. The driver applies the Vmot voltage (in my case 24V ) to the coils and varies the current to move the rotor, without exceeding the max current ( set by Vref ). Am I correct?
I found the noise issue. The motor vibrations are amplified by the enclosure, so a damper is going to be required.
It sounds like your understanding is mostly correct.
The stepper motor is rated for 1.7A per phase, and it draws that rated current at 2.8V (i.e. the rated voltage). If you apply a higher voltage than that to a coil, it will draw too much current, which will overheat and possibly damage the motor. To prevent this, the driver essentially turns the output (which is at your VMOT voltage, 24V in your case) on and off rapidly to actively limit the current through each coil.
If you want a more detailed breakdown of the current through each coil at each microstep index, you can find a breakdown on page 14 of the DRV8825 datasheet.
Brandon
OK, I understand it fully with that link. Using that data, I will change from divide by 2 (mode 100) to divide by 8 (mode 110 ). Which I think will reduce the vibrations by reducing the rotor Inertia. meaning less noise,
This is my first stepper motor project.
Thank you for sharing your wisdom.
