3phase motor and pulley

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10 Sep 2024 11:41 #309833 by russkinch
Good afternoon all.

I am rebuilding my lathe and have decided to use a 2:1 toothed belt on my 3 phase motor, giving less rpm but more torque as I never use the high rpm. My question is, I have an encoder that is driven from the spindle and not the motor. My VFD is set as per the motor specs (top RPM at 50hz is 2840 rpm). How do I set my HAL file and do I need to?? My max RPM would be about 1420 or so based on the 2:1 reduction.

Thanks

Russell

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10 Sep 2024 12:10 #309834 by andypugh
Replied by andypugh on topic 3phase motor and pulley
You can probably do this in the VFD settings, if you want. (depending on how it is controlled)
Otherwise, yes, ideally you would use some scaling function in the HAL to convert the commanded speed to motor speed.
But you probably already have this somewhere, I imagine that something takes spindle.0.speed-cmd and coverts it to a PWM duty cycle or similar? Just change the scale factor there.

How is the VFD controlled?

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10 Sep 2024 12:39 #309838 by russkinch
Replied by russkinch on topic 3phase motor and pulley
Yes, the VFD is done through PWM. You kindly helped me many years ago setting this up. The Chinese BOB PWW and GND go to the VFD (Bosch) on GND and A1. I hav ethe 24V fromt the VFD also running through the relay on the 2 BOB's that I am using. I am using two as I need more than 5 inputs. I was hoping to use Mesa but stock is a massive issue. So my HAL was written using Stepconf and I put in there the max speed of 1420 at a full 10v. I assume Linuxcnc will think it is 1420 but the VFD will be running the motor at double that which I assume is OK as the encoder is on the spindle and not motor

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