Hi!
I am starting my first CNC project - retrofitting mill Mazak V10.
It was cheaper to buy old and heavy 8 ton Mazak instead of retrofitting my old manual mill.
Mazak is good donor: motors, transformers, ball screws, limit switches, excellent guides, tool changer etc. - everything on place and ready to start :-)
For XYZ everything is clear(more or less) - UHU!
motors(Fanuc):
X - 137V 12-16A
Y - 137V 12-16A
Z - 137V 30-37A
But biggest problem at the moment is the spindle motor.
Motor is DC 220V, 35A cont., 45A max for 30min.
I am thinking to use UHU servo controller too but with biggest mosfets.
And question is: may I replace IRFP260 with IRFP4232 (250V, 60A) ?
http://www.irf.com/product-info/data...rfp4232pbf.pdf
http://www.irf.com/product-info/data...a/irfp260n.pdf
What else must be changed to employ IRFP4232?
Or other solutions aviable?
May be it is waste of time to use UHU servo controller on motor like this one?
I really would like to read some honest comments/solutions from electrical persons about this question!
Regards,
Oscar
Where can i buy assembled and working boards or boards and parts to assemble them. Im in the USA, in texas.
Thxz, Mat.
Assembled and tested
http://www.bgmikro.com/
Also you can look here:
http://gsst.wikispaces.com/UHUget
Regards,
Oscar
Oscar;
The UHU board is made to control mainly Permanent Magnet type, Brushed DC, motors with encoder (aka Brushed Servo motors). This motor is in another league, You need a different controller that provides voltage for the field coil (speed control) and armature current control (for controlling torque).
On the other question; Both Mosfets could be employed (not mixed).
Thank you Kreutz!
Your answers as always - like gold!
But one point is not clear to me about motor.
Why I can't just connect constant voltage 65V to armature, add encoder and control it like permanent magnet motor?
Look at permanent magnet motor - it has constant magnetic field...
And how you can control armature current, with voltage..?
Ok, lets say there is no way to this motor together with UHU. Then is it possible to use regular three phase asynchronous motor ~900 rpm + 0-400hz VFD ?
Regards,
Oscar
The controller that went with that motor varied the armature voltage up to the low RPM rating with full field amps, at that point the field voltage starts to decrease to achieve the high RPM. That is why you see 2 RPM ratings and 2 field current ratings. This is what is known as field weakening. Most of these drives also incorporate field economy, after setting idle for a minute or two the field current is reduced until needed. Keeps the motor cool.
Darek
Darek, thanks for answer!
You are right for 100%. Nobody 200km around here can restore that old (1979) motor controller without circuit. Even somebody will do it then connection to Mach3 will create new problems.
Of course I can buy commercial drive for 2000-4000USD but that is not what I am looking for - low cost solution (like others in this forum).
Please look at these possible scenarios:
1. simple.
UHU + independent micro controller based controller who read motor rpm and adjust armature voltage.
2. more complicated.
UHU + independent micro controller based controller who read motor rpm + current sensor who reads motor current
- set voltage according to motor rpm
- read motor current and adjust voltage. works like "field economy" as you described before.
3. Easy, not cheap, I don't know how practical......
3 ph. asynchronous motor + VFD
Regards,
Oscar
If the controller is a Mitsubishi like the motor, you should be able to download the manual on the Mits site that includes the schematics.
Darek
Hi all, great thread.
Read the whole thing in the last few days! Have a question I don't think has been asked before. Some background first.
I have recently ebay'ed some 4 brush 1200 in-oz motors with these specs:
continuous current 7.3 amps
peak current 75 amps
torque constant 18 in-oz/amp
voltage constant 13.3 V/Krpm
I had originally planned to use Gecko's figuring the 20 amps would get me 360 in-oz peak and easily handle the continuous (130 in-oz). This should be enough for my Shoptask Tri-Power Lathe-Mill for hobby use. Being the insane DIY'er I can't resist the lure of 30 amps for 50% more peak torque and being able to build and repair it myself.
Now the question. Unlike those who desire the UHU for it's greater than 80 Volts, does it make sense to expect to see a performance improvement from it's greater than 20 amps? In all these posts I haven't seen any use of more than 14 amps. Is the board really up to 30 amps?
Thanks in advance for your recommendations.
You need your motor's datasheet in order to evaluate if it makes sense investing on a higher current drive. Basically most of the sellers advertise stall torque instead of the continuous torque, both figures are important, but you dont want to work more than a few seconds above the maximum continuous torque, otherwise your motor is going to get damaged.
Hi,
I bought these motors blindly and now unable to understand that the transducer attached is either an encoder or a resolver.I thought it to be encoder.
Beside the pics attached following is written on the transducer.
BALDOR ASR Servotron (Made in Germany)
Written on transducer:
Type ENC DG 60 2500 imp/5volt
Impulsgeber type DG-60/1
Imp/U 2500
F 150KHz
If it is an encoder with 2500 ppr than i am afraid that i will be unable to use them with UHU.
Any body here know about it ???????????
Hi ??, (Why do you never use names here...???)
this is for sure an encoder. With 2500 cpr it's really heavy load for the UHU and will limit performance/speed. A 'good' encoder is in between 250 and 1000 cpr.
I have no idea if the two quadrature outputs are Ua0/1 or Ua1/2. The inverted Outputs are of no use in the standard UHU layout.
It is necessary to check if the outputs are TTL level or another signal level like 1Vpp, 11uA or a strange differential interface. An oscilloscope is needed to find out of what type the interface is.
Over all I'd say, this motor is not ideal but might work.
Uli
Hi,, I´m new in this servo thing, i wold like to know how critical the value of c1 and c2 are. is it possible to replace with 22p or 33p. the supluer i use dont have the 27p.
This cnc stuff is realy fun and i am going to explore it some more. My little experimental router is bastardly slow with stepper motors and my driver that i use is a DIY from plans "out there some where"
Thanks / Anders
Thanks,, But i have to go with the kit´s. they cost a litle bit more than i have to pay for one from "my" suplyer.
Thanks for the reply /Anders
Thanks, Allan!!!
For some reason I assumed it was 20 Khz, Thank you again. The difference is going to affect the power calculations (increase the calculated power)), but since we ended up choosing higher power resistors (for practical purposes), there is no damage done. I will keep it in mind for future calculations.