Controll stepper torque with pwm

Other Hardware Motors, Mechanics, Power and CNC
1

hi,
i've a nema 23 stepper motor, 3A - 0.95 ohm, for this project i need to controll the torque of the motor:
from my code i recive a pwm signal (0-255) that rappresent the % of torque i need to generate from the motor.
i've searched for a driver with dynamical adjust of current but i haven't found anything.
can someone give me some tips or reference to documentation?

thanks all,
LC

2

IF that is the real requirement, then a stepper motor is the wrong choice. A stepper has turning torque when it takes a step. It also has holding torque when stationary, between steps. They are very similar values. There is no easy way to adjust the current being produced by a stepper motor controller board.
Perhaps the use of a regular DC motor will work for your project.

3

i've thinked to use DC motor, but they have too small quantity of torque.
also i need a "Brake" usage of the motor.
i need my motor torque to be adjustable so you can rather win the forces applied or slips steps when it's to low.

4

Some drivers allow to adjust the maximum current and control that current by self-generated PWM. Typically the current is set by a pot, while you need a different adjustment method. If you cannot find a controllable current limit driver then I only can imagine an additional circuit that affects the PWM generation.

5

i currently have a TB6600, wich allows me to adjust current to 3.5 Amps or low with a pot, i was thinking of getting a PWM mofset to use on DC input of the driver.
could this work as intend ?

6

That's my idea as well. Good luck with figuring out the required circuit.

7

i've made some experiment, and sadly it doesn't work...
i've succeced to reduce torque, and increase it manually turning on and off the switches and i've searched for a new stepper controller with adjustable curret limit signal (current one "TB6600" has switch pot ) and i've found the DRV8825, too bad it's only 2.5 amps.

if someone can advise me with a more suitable driver would be very lovely.

8

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