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Servo motor act as generator

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Member level 2
Dec 10, 2012
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Hi everybody,
We have special purpose dc servo motor on a machine. Motor has 7 input pin which are
vdc +
Vdc -
Serial tx
Serial rx
Canopen Can_H
Canooen can_L

Our problem is motor work normal when machine is powered on. When there is no power on machine, there is a handwheel on the other side of metal rod and user try to make positioning by hand. Motor is connectod to rod directly and servo motor act as jenerator and makes noise. Motor driver is integrated inside motor and we can't do anything to driver. is it possible to do something when there is no power do solve noise problem. For example adding a diode or anything between power?


isn´t this contradicting?
Motor driver is integrated inside motor and we can't do anything to driver.
.. but then you suggest:
For example adding a diode or anything between power
So either you can or can not do anything.

If your idea is to add a diode than you "can do" anything.
To me it´s unclear what´s possible and what is not possible.


Hi klaus,
As i said driver is integrated and we can't do anything to driver. i meant to adding a component to power supply input. Or any other suggestion to disable knocking noise when it is operated by hand

Back diodes might load the output-as-generator much more in one direction than the other.

But don't assume that the geartrain (?) is designed or set up for symmetry either. A precision mechanism probably registers specific faces and lets their opposites float under some modest tension, which back-cranking might put into unaccustomed engagement, engage some coaster brake or whatever.

I don't get a sense there's any method here.

Not sure if you actually proved that the observed "noise" is caused by generator action. But if so, is it different when the digital servo is disabled but connected to the power supply? Or when the supply lines are disconnected instead of being loaded by the external supply and parallel connected devices?


I don´t know if you talk about accoustic noise or electrical noise ... and what´s the actual problem of this noise is.


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