Newbie- help on power supply

[willheg]

hi there people

i am looking at building a power supply for a cnc router that i am building

i have 4 stepper motors rated at:
Step Angle (deg) : 1.8
Motor Length (mm) : 112
Rated Current (A) : 4.2
Phase Resistance (ohm) : 0.9
Phase Inductance (mH) : 3.8
Lead Wire (No.) : 4

i also have a 36v 120amp dc motor i'm looking at using for the spindel motor

but may add a 12v motor for a coolant pump

the local voltage here is 240v ac what i'm wondering is what compants i would need to build the power supply to run these motors and if anyone can help me out,
also wondering what driver board anyone would use or build to run the steppers

cheers if anyone can help
William

[acondit]

William,

It sounds like you might need a DC arc welder to drive the spindle motor. That is serious amperage. The rest of the stuff is quite doable, but seriously, I wouldn't know where to begin with what you are considering for a spindle motor.

I use a 35amp 400v bridge rectifier in my ps with a 23v AC secondary on the transformer (110v to 23v 400VA). I figure it is good for somewhere around 12-15 amps at 32V DC.

What you need (or can use) for secondary voltage depends on the drivers that you choose. Mariss gives formula for the max voltage for a stepper motor as (32*(sqrt(Inductance)) so 32*Sqrt(3.8)) = 62.38v. If you were using a Gecko G540 drive that would be higher than the drive max of 50v (so you would need a 50v supply). If you were to use G203 drives that would be less than 80v max for the drive, so you could use the 62v supply.

Then if you also want 12v supply you either need (1) approx 12v windings on the xformer, (2) a separate 12v supply, or (3) a circuit to derive the 12v from the high voltage supply. The higher the amperage requirements for the 12v supply the less likely that #3 will work.

For a filter capacitor the formula is C = (80,000 * I) / V. C=capacitance in microfarads, I is current in amps, and V is voltage. So you need to decide on the voltage and current needs in order to properly size a capacitor. Also remember to get a higher voltage rated capacitor than your output voltage.

Alan

[willheg]

thanks for the reply this should help me a bit more but i'm still a little lost on the transformer to use and drivers, i take it your saying i should opt for a gecko drive, the problem i have is i'm in new zealnad and the exchange rate ant flash and money is tight but yeah might have to try and save my pennys, haha

can you recommend any sites that would help me with information on what i need on the power and driver side of things as i feel i have the table and everything else sorted.

the motors are as i said in my open question, i'm looking at running EMC2 all i need to sort out is the power and drivers

anyway anymore information you or anyone can supply me that would be great

cheers

[Al_The_Man]

That 120a motor is approaching 6hp, it is unusual to see a motor of that HP at that voltage, unless it is a traction motor used on mobile equipment.
In that case, you should check to see if it is a wound field series motor, if so, even if you find a controller for it it, a series motor will not work for this application.
(you will get run-away with no load).
Al.

[Crevice Reamer]

Hi wilheg!

If I were you, I would buy the Gecko G540 from Keling. He seems to find the most reasonable shipping costs to your neck of the woods.

So $299 USD gets you THE BEST 4 axis plug and play controller with built in high tech break out board.

This will cost you a small bit of motor torque as it will run your 4.2A motors at 3.5A, but this should nt present a problem.

You might find it less expensive to just also BUY the $129 Keling KL-5010 PSU.

$428 for electronics.

Keling also has a $10 Estop switch, $2.20 Home/limit switches, a $8 parallel cable and assorted motor couplings. Check out his site:

http://kelinginc.net/

CR.

[willheg]

i'd like to thank you people for replying

1st thing is i'd like to correct myself by saying th spindle motor is not 36v 120amp it is a 24v 12amp motor that can be run at 36v if needs be

anyway back to what Crevice Reamer was saying and just would like to thank him for the site address there is a lot of good stuff on there but wonedering why you would go for that power supply would be ok to drive the 4 steppers i have

i have heard of something called back emf?? and wondering if this is why this power supply was sugguested instead of the KL-5020 or KL-5413 and just currious how pepole come up with all these answer or if ine of those to would be better and why, guess if you dont ask you dont know

i'm only wondering as i'd like to get as much out of the motors as possible or what is the point having it all.

now on the controller front, i was looking at a seperate board for each of the steppers to be able to un them at the 4.2 amps they have, wondering on what would be the best brand or if i was to go for either a gecko G201/G202/G203v/G210/G212 which one and why or the other opition i have now found is a KL-8060/KL-8078 from Keling tech. and wondering which one to go from there or which brand/driver and why.

cheers
william

[Crevice Reamer]

Hi William! Back EMF is not a problem with G540 and I chose the lowest cost solution for your application. G540 will only work with 50V or less, so no 5413.

To get the same G540 performance and reliability out of separate drivers, you would need the $149 EACH Gecko G203Vs. While you COULD go with the $60 each KL6050s and use your present motors, I would recommend instead Using the G540 and buying 3 new $39 KL23H276-28-4B 270s for X and Y and a $49 KL23H284-35-4B 387 for Z. (OR 4 of the new $49 KL23H2100-35-4B 318s) Keling gives a $10 G540 discount when you buy motors.

This will give you the best possible performance and you can sell the other motors on ebay. You COULD also upgrade to the KL5020 PSU if you feel more comfortable with extra Amps.

The G540 is a revolutionary CNC product. It incorporates into one tiny plug-&-play package: 4 mini-203V excellent drivers, a breakout board, a Logic PSU, Charge Pump, Limit/Home connections, and outputs for relays. It even comes WITH connectors for motor cables. It is the wave of the future and it would be a shame for you NOT to take advantage of it. Here's a new commercial router using G540 for you to check out:

http://cnczone.com/forums/showthread.php?t=72426

And a homebuilt W/G540:

http://cnczone.com/forums/showthread.php?t=73980&page=3

The black panel you see in the pics is the ENTIRE g540. It extends about 1 inch into the case.

CR.

[willheg]

just a quick post to see if this combonation sounds good for what i'm doing

i'm looking at using the 4 steppers i have listed
running 4x G203v Gecko boards
1x C11G Break out board from Keling
1x KL-5413 power supply also from Keling

the only problem is running the EMC2 i am looking at using a 2nd port from the computer so i can wire all home and limit switches 1 per termial and wondering if it would all work ok or would i be better to just wire all limits to 1 and all homes to 1 to kep things easy

and using the 2nd port would i need a 2nd BOB or could i just hard wire them?

also is everything listed above sound like a good combo?

another thing is could i just build a cheap driver board myself then make another board to get driven buy the fisrt board with the voltage i need for the motors if you understand what i mean

cheers
William

will prodaly be more questions later but all help is thanked