What is needed to drive a servo motor?

[Greg Q]

Hello experts...

What is needed to drive an AC brushless servo motor besides the drive? And for that matter are drives usually propriatary, or are there some universal type drives? (I'm talking about 10-12 amps). Application would be a spindle motor for a lathe, so only require speed and fwd/rev controls.

Thanks for any assistance...

Greg

[rodm]

As nobody has responded and given I am the worst person to reply as it involves mumbo jumbo electronics I suggest you contact this person.
http://www.homanndesigns.com/
Peter will be able to answer your question and probably has something on his shelf that will do the trick.

[seafurymike]

Hi Greg,


any reason for AC drives. Just that there is a limited supply of controllers and knowledge on this at the moment.

I assume you have a couple of these motors handy?

/M

[Greg Q]

My reason is part ignorance, part imitation. On the Practical Machinist forum there was a thread on the use of a 2hp AC servo powering a Monarch 10EE lathe. Very good results.

I have a similar lathe that I am restoring; it is a single speed belt driven toolroom lathe (with back gear). I need therefore a motor that will deliver full torque at (say) 30 rpm and 3000 rpm. A brushless servo is the only beast that will do this very well. My other choice is a 3 hp three phase induction motor and a constant torque vector drive vfd. Preferably with an encoder feedback to the drive to ensure constant rpm at the spindle.

The servo would also (I guess) allow me to implement a constant surface speed function on the lathe, and also dovetail nicely with an electronic leadscrew project down the road. (Sort of an NC lathe control for things like crew cutting, feed rates and auto tapering)

The downside is cost: A new servo and drive in the 2.2 kW range would be easily $3000-beyond the budget. Being a bottom feeder I am left to the usual channels of supply, so it might not happen by the time I finish the rest of the (many many) restoration steps on the lathe.

I don't know enough about DC servo motors to judge their suitability for my application.

(I have high amp 240v single phase AND 240v three phase from my RPC available for feed power for whatever motor drive I buy.)

Greg