Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


VFD Torque Control

VFD Torque Control

VFD Torque Control


I want to determine the break-away point of a brake driven by a motor. My plan is to gradually (or incrementally) increase motor torque from 0Nm until the brake gives way, I will use a torque sensor to measure the torque and the motor encoder to determine the point of break-away.

The question is what is the best way to control the motor to achieve this? Is it possible to achieve accurate motor torque control from 0rpm with closed loop vector control? Or would a better option be to use feedback from the torque sensor to achieve control?

Unfortunately I'm not very clued up on the subject so any pointers to useful information would also be appreciated.


RE: VFD Torque Control

Save a lot of money and time.
Use a torque wrench and do it manually.
Probably more accurate also.

"Why not the best?"
Jimmy Carter

RE: VFD Torque Control

I was just going to say the same thing.

Failing a torque wrench just us a mondo 6-point socket and long piece of pipe. Failing that, use a standard torque multiplier and a long piece of pipe.

The problem with a motor, besides totally thrashing it thermally, is that you'll likely have some serious torque cogging that will mislead you in the results. That's totally avoided with a wrench.

Keith Cress
kcress - http://www.flaminsystems.com

RE: VFD Torque Control

You have to have a speed control loop, and this will have to be the primary control loop. Static friction is greater than dynamic friction. So when the brake starts to move, the resisting torque drops and speed will go out of control. For this reason, many attempts that I have seen to use torque control of motors do not work well.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


White Paper - A Guide to 3D Printing Materials
When it comes to using an FDM 3D printer effectively and efficiently, choosing the right material at the right time is essential. This 3D Printing Materials Guide will help give you and your team a basic understanding of some FDM 3D printing polymers and composites, their strengths and weaknesses, and when to use them. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close