[ravngr]

I'm planning on a CNC mill conversion and tossing up between steppers and servos. While I'm relatively familiar with stepper motors form other projects, brushless AC servos are something new to me. Looking around it seems to be a lot of options but relatively little discussion on how to match up motors to drivers. From what I've seen there's a lot of choice between different servo motor and drivers rated at a variety of voltage, current and power ratings and I'm a bit lost in it all. From what I have found online I'm most interested in brushless AC servos in the range of a few hundred watts.

When matching drivers and motors up what should I be looking for? I'm in Australia and on 240V single phase, does this directly affect the output voltage of the servo drivers? Is the output voltage regulated in any way? If I do get motors at a lower rated voltage than the mains/servo driver output can I lower the driver output voltage easily (or can the drivers be modified)? Does it all not matter and the magical driver takes care of it all? Just looking for some guidance on how I can set this whole thing up safely. Thanks in advance!

[Tkamsker]

Hi it is simple as math
Measure the force you want / Must supply think of the Speed you want to achieve ,.. Then Look at the provided Charts add Safety margin then do Excel to compare what you get and What you Pay for then decision is Easy ,.. I now kept Old servo on an bridgeport 412 but we Tried Steppers verry verry Hard -

[Al_The_Man]

There are basically two types of brushless servo's, BLDC and AC sinusoidal, they both are constructed the same but have different commutation.
The easiest to sub drives is DC brushed, followed by BLDC (Brushless DC), the hardest is usually AC sinusoidal due to many manuf having their own method of commutation or one that does not lend itself to intermixing drives.
If you want a sizing program, Kollmorgen have a free one on their site to give you an idea of sizing.
One of the most demands placed on servo's/steppers is the accel/decel rate required for a particular machine.
Al.

[ravngr]

OK, so once I pick a motor and wattage (for arguments sake say brushless DC at 200W) I want then what should I be looking for in a servo driver? Basically I'd like to know how to pick a driver that will work with a particular motor. Additionally are encoders pretty much universal or does the driver have to support a particular type (magnetic, quadrature, etc)?

[alan_3301]

Best bet is to get a matched pair.
Or find a reasonably priced drive on ebay, find the documentation, see if it meets your needs, Find the matching motor numbers in the docs, and search for that on ebay to see about price/availability.
or find a nice priced motor, find docs, and see if matching drive is available.

another option is chinese motor drive kits, http://www.ebay.com/itm/200W-CNC-Dig...item233c18d430
for example. no idea about performance or reliability, but I'd be interested to hear if anyone has tried them.