servo recomendation WHN 11

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02 Aug 2018 12:24 #115398 by vre
Replied by vre on topic servo recomendation WHN 11
motor is rated 100VDC 26A so no pico no mesa drives are suitable.

With a half bridge circuit (half bridge driver + 4 suitable mosfets)
i will drive it with pwm from linuxcnc.
The feedback to linuxcnc will come from linear scales each axis has.
Motor does not have encoder is is a simple large brushed DC motor

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02 Aug 2018 12:27 #115399 by andypugh
Replied by andypugh on topic servo recomendation WHN 11
Without an encoder on the motor I don't think you could use the UHU.

a 26A motor would probably move reasonably well at 22.5A.

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02 Aug 2018 12:32 - 02 Aug 2018 12:46 #115400 by vre
Replied by vre on topic servo recomendation WHN 11
I know UHU is a servo driver.
I my case all i need is a half bridge driver not a servo driver.
I have found on aliexpress huge mosfets with h bridge driver
www.aliexpress.com/item/free-shipping-5P...100/32846181911.html
www.aliexpress.com/item/10PCS-LOT-IR2184...P-8/32831837558.html
But this is an incomplete circuit because it has no current sensing...

IRFP260N has
V DSS = 200V
R DS(on) = 0.04Ω
I D = 50A
Witch is ok / mosfet at saturation has 26A x 0.04Ω = 1.04V voltage drop about 27W thermal losses
of course at switching situations power losses are far more but with a good heatsink with a fan it will be ok.
These mosfets have very low RDS(on)
I think i have in my stock very low rds(on) high amperage mosfets from a spot welder project..
I have 10pcs of these www.infineon.com/dgdl/irfp4368pbf.pdf?fi...00a40153562c61512015
but the are 75V rated so not lucky...
Last edit: 02 Aug 2018 12:46 by vre.

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02 Aug 2018 12:48 #115401 by tommylight
@ vre
You need a H-bridge, that is not half bridge, that is a full bridge.
A half bridge can drive a motor in both directions, but only with 2 power supply voltages, so +-100 V in your case.
A full bridge is used exactly for avoiding using 2 power supply voltages, and for some other reasons.

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02 Aug 2018 12:55 #115402 by vre
Replied by vre on topic servo recomendation WHN 11
Yes you are correct.
I think these mosfets are ok so iam searching good driver to drive them
and a method for current sensing without losses.

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02 Aug 2018 12:56 #115403 by andypugh
Replied by andypugh on topic servo recomendation WHN 11
You could try this:

www.ebay.com/itm/182705433680
The following user(s) said Thank You: tommylight

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02 Aug 2018 13:09 #115404 by vre
Replied by vre on topic servo recomendation WHN 11
This is a very good option...
So the only problem remains is how to read analog scales..

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02 Aug 2018 13:16 #115405 by tommylight

andypugh wrote: You could try this:

www.ebay.com/itm/182705433680

That looks usable !

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