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Linear Motor Service mode | 31 Jul 2023 | |

Linear Motor Service mode

Hi, we are trying to operate ironcore ICH22-100 motor with AKD-P 012 07 servo driver. In the service mode in workbench in velocity mode, we see the velocity feedback to be oscillating and have a lot of noise and spikes when motor is at constant velocity (in a trapezoidal motion).  

Is it a tuning problem or is it something else that we should do?

Thank you

Comments & Answers

jcoleman02 | Mon, 07/31/2023 - 13:38

That is typical with low resolution encoders, but can also be seen somewhat with high resolution encoders.  It could be caused by the internal drive calculations, in which case there is no need to worry about it.  However, if it's caused by actual noise (EMI) on the feedback signal, then that needs to be fixed.  For 400/480V system, please follow all of our standard recommendations for mitigating EMI.

Normally a linear motor is not run in velocity mode, which leads me to believe that you are using Analog Velocity mode and closing the position loop in a controller.  If this is the case, you could be seeing "noise" from the analog input signal.  Make sure the analog input signal wires are shielded.  Make sure the AKD drive's analog input is grounded to the same ground point as the analog output of the master controller.  You could put the AKD in Service Position mode and run it to compare with analog velocity mode.

Tamim | Mon, 07/31/2023 - 14:32

Hi, Thank you for your reply.

We were using the Service Velocity mode in AKD and saw those results. Yes we close the position loop with a controller but that is independent and these results we got were from the AKD workbench with the controller not yet connected.

Later, when we connected the controller, we saw a lot of disturbance and spikes in our FFT graphs (from our own software).

Also we wanted to ask how easily should the motor slide on the magnetic pathway when we try to move it manually, we noticed that if we change the preload of our bolts used, we can change the ease with which we can move the motor (without the load) manually. 

Thank you.

Regards,

Tamim

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Tamim
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