Help with AC servo setup

[h3ndrix]

Hi ppl,

I just got 3 of these motors;



The motors do not have encoders on them and I believe they need shaft type encoders with couplings, but the question is do I need encoders?

I guess the bigger question is, how would I drive these motors with a economical setup? I want to use Visualmill, so I would like to use my PC as the controller.

Basically, what is the whole setup and any recommendations on certain, economical products are welcome

thx,

H3ndriX

[Al_The_Man]

Those motors look like allen bradley type and usually have a resolver fitted for direct feedback to the 1394 series digital drives. It will be tricky to use them with other drives, unless you can get the pin out of the connectors and use the resolver output into 3rd party drives such as A-M-C or Copley Controls sinusoidal type AC drives, also I believe these are 460v motors?.
Unfortunately some manufacturers motors do not lend themselves to mixing drives without some reverse engineering.
Al

[HuFlungDung]

Al,

How can you tell all that from that chart?

But, if V/1000rpm =49.5
and max rpm = 4000
then
200v would be the maximum input for the motor, would it not?

H3ndrix, you might as well go "whole hog" and get yourself some encoders for them. You must have feedback for a servo system, otherwise you have just bought a bunch of continuous running motors: we call them runaways Some of the guys on these forums have gotten some fairly inexpensive encoders from somewhere.

How else will you get position? There are no inherent steps to the way a servo motor works.

[h3ndrix]

well, I dont know much about this stuff, but I read that you can run them using the internal hall sensor that is inside the motor instead of using encoders. I dont know what this means exactly as I dont have the motors yet in my hand.

lets say i get encoders on them, then can I run them with other drivers?

The motors are rated 230V btw.

h3ndriX

[HuFlungDung]

H3endrix,

I'm reasonably sure that encoders are still required. Just going by what I have on one of my machines here, AC brushless servo with 10,000 line encoders. This is a Mitsubishi retrofit, but it is likely typical.

I believe that AC brushless servos require 2 input axis for each motor on a motion control card, like a Galil. That would mean you need 6 axis. Each motion card typically has the limitation of 4 axis per card, thus, 2 cards are required.

When Al wakes up, he'll tell us for sure

[Al_The_Man]

Hu, is right, if you want sinusoidal commutation, (very smooth control at low rpm) then you require a controller that will supply two sinusoidal outputs per amp, the third phase is derived from the these two. You will need an encoder back to the controller, and the hall effect sensors are usually for initiall armature position sensing and the the commutaion is done through the encoder which obviously would have to be on the motor shaft, some systems use a resolver for armature position and also is used as an encoder system, if your motors have hall effect, I would be suprised if they don't also have incremental encoder tracks on the same disk.
A good source of information is a AC servo handbook on the Denki web site www.motiononline.com also look on the Copley Controls site for AC servo manuals manuals, AMC used to put out a good text but I see it is no longer on their site, but if you get their catalogue it used to be published in the back of it.
If you just have the Hall effect outputs, you may be able to use a trapezoidal amplifier or brushless DC.
One of the features of the sinusoidal amplifiers were very low cost as compared to other types.
Copley and AMC amps come up on ebay all the time. You should also be able to get the motor details from you local AB rep or from the AB web site.
Al

[h3ndrix]

Thx Al and Hu,

I actually do have the whole product documentation on the motor, but I dont have the knowledge to understand what it all means.

AMC, copley and AB amps are too expensive for my current situation, and not only that, they require controllers. I am interested in controller+driver setups (like rutex) where I can just plug into my PC, without too much fuss.

Thats why I am interested in just hooking up an encoder to these motors and running the with Rutex 992H drives, if it is possible. I wish I could use sinusoidal (from AMC), but its just too much.

thx

H3ndriX

[Al_The_Man]

H3, These appear to be for DC brushless motors which you may be able to run your motors as such.
Also they are limited to 100v DC max.
You will need to know the comutation angle of the hall's , 120deg is the most common.
Good Luck
Al

[h3ndrix]

Thx for the reply Al,

Yes they are 120 degrees, I just checked the manual. Rutex says they have the 992H for different voltage and amp configurations, which is what I need, like you said. Hopefully I ll get my hands on some of these and let you guyz know how it worked out

Thx again

H3ndriX

[arvidb]

H3ndriX,

any luck with those motors? I would be interested in hearing your opinion about the Rutex 992H, if you went that way.

Arvid