DC brush motor issue 1

[lmuri]

Hi,

I met a problem with a DC brush motor recently. The whole system is relied on a DC motor controller and a small DC brush motor from Maxon in a current control mode. The current through the motor is adjusted by a analog output from a DAQ card directly. Recently we noticed that when the current is close to the maximum current on the amplifier, it will drop automatically.

Is it a standard problem seen in the DC motor control?

Another potential issue with this system is that the PWM driven current went through a cable 10 meter long. Will this be an issue too?

Best.

Ming

 

[Skogsgurra]

Some output stages and power supplies have so called "fold-back" current limit that behaves just like that. It does so in order to prevent the transistors from overheating.
I guess that is what happens in your servo. What type is it and how much current is the motor drawing when it happens?

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[lmuri]

Than you for the quick reply. We had an ADS 50/10 and its theoretical current capacity is set to be 10A. However, the current drop can happen at 4A based on the feedback signal from the controller. There is a secondary current limit on the controller which should not be activated, however, it seems that this current limit might be on.