Motor Drivers for Torque control

Hi,
I am working on a project that requires to control torque of DC motor. I want to know whether there are ready made motor drivers available for this purpose. I got a lot of list on speed control motor drives but i am actually interested in current control and not PWM based voltage control.

How do you plan to know what the torque is at any instant? How would you control the current without it affecting the voltage?

Paul

What I want is a motor driver like L298 but with current control, is there anything available on the market with torque control that can be used with Arduino

thekid289:
Hi,
I am working on a project that requires to control torque of DC motor. I want to know whether there are ready made motor drivers available for this purpose. I got a lot of list on speed control motor drives but i am actually interested in current control and not PWM based voltage control.

This is the realm of servomotor controllers. That's proper servomotors (not hobby servos which are
servo-mechanisms, not servomotors proper).

Most servo motor controllers have an inner current control loop and various feedback modes run on
top of this including pure current control (which is torque at the shaft).

I think the ODrive (which is open source) has a torque control mode.

I guess my question is why ? The “torque needed” by a motor is that required to drive the load , you could limit current - but if that is not enough current to drive the load the motor will slow or stall.

It might help to know the project

One use of a torque limited motor is as a tensioner for some line, when the other end can move
under control of something else. Torque limiting can also be used to prevent damage on hitting an
endstop.

Please tell us what the actual application is rather than just saying you need torque control.

You can control torque by controlling speed via PWM, you just need to measure the current. When you control torque, the speed is no longer controlled, it becomes a function of the motor load.

You can control speed or you can control torque, you cannot do both at the same time. There are cases where you don’t care about speed but they’re not common.

In a permanent magnet DC motor:

Voltage applied = speed
Current applied = torque

If this is a one off application or for proving a concept, a properly sized DC bench power supply with adjustable voltage and current limits can be used to control a motor which would provide you with adjustable speed (voltage) and adjustable torque (current).

Below is a link to a YouTube video for an application that needs torque control. The reason is the rather high inertia of the load which overloads the motor because it does not have enough torque to accelerate the load to speed in a timely manner.

The this could be achieved by using the built in speed control or with a simple variable ac transformer (variac) because it’s a universal brushed dc motor inside the device.

Watch the intro then skip to 6:45 for the lack of torque control problem.

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