MM440 micromaster Max Torque control

userxyz

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Hey,

I have a 2,2kW motor that runs @ 50Hz with an MM440 frequency drive. The drive is connected on profibus.

Because of the load, the motor never may reach it's speed setpoint. Can be done with the Torque.

So the motor speed setpoint is 50Hz and the actual speed should be slower. It's a rollerhead that needs to give tension on carpet.

It has nothing todo with my other projects and please don't write that I must work with the speed to create tension instead of a hybrid of speed and torque, it must be done like the bosses want.

So, what I do:

I send a processvalue to PQW274, that is connected to WORD 2 of the drive and I linkt it with 'UPPER TORQUE LIMIT' P1522. The torque can be given on an OP7. Minimum torque is 1,8 Nm and max is 22,13 Nm. It can be red in Read parameter r1526.


So I limitate the torque and use the drive in Vector control.

This question goes to the MM440 specialists:

How would FCC respond to this situation ?

And is it better to work with torque control then limitate the torque ?


It works right now, but I'm wondering if it could be done in an other way too ?


Greetz (regards)


CoMBo
 
Combo said:
This question goes to the MM440 specialists:

How would FCC respond to this situation ?

FCC?

Combo said:
And is it better to work with torque control then limitate the torque ?
It works right now, but I'm wondering if it could be done in an other way too ?

CoMBo

For me, it's mainly a hold-over from my DC motor days, but I much prefer to control the torque LIMITS as you are doing currently. There are applications where I do prefer to directly give a torque command, but they are few and far between currently.

By clamping the torque limits, you still have an outer speed loop that will 'take control' if you lose the load connected to the motor, thus limiting the speed. If you are purely controlling torque, and lose the load, the motor will accelerate to some speed in order to attempt to satisfy your torque request.
 
tnx

Tnx for your reply.

I think so too, that the torque limitation works fine

I put an screenshot in a zip file

The Operator can give a torque 0-100% on a OP7 and it's calculated that the torque is between 1,8Nm and 22,13Nm

Greetz
 
I am not an "MM440 specialist" as you say but I may be able to offer some useful input.

Many vector drives have the ability to operate in speed control with a torque trim on the speed reference. Some have the ability to operate the torque trim as a setpoint (PID) control for excellent control during upset conditions.

Adjusting the torque limits on the fly is an interesting way to accomplish a similar control scheme. Never seem it done but seems useful.

Are there issues you still need resolved or was your post mainly as an update?
 

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