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AC servo as spindle motor drive?

A compatible servo drive. Technically any good servo drive of the right power rating could be made to work, but a Yaskawa drive would likely have pre-loaded motor data available in programming by a look-up table using their part number, otherwise you will have to gather and load a lot of motor data into it yourself.

That said, if you don't already know all of this, you might be biting off a little more than you can chew. Servo drives are way more complex than basic VFDs.
 
+1 on the horse trade. 5kW is a fairly big servo, hard to come by. That generally translates into value if you find the right venue to offer it up.
 
If you're doing robodrill style drilling and tapping (blink and you miss the whole cycle) a servo makes sense for a spindle. They're designed for blinding accel/decel. Or if you need re-tapping. Or orientation for a broaching cycle .

And if you mean a _manual_ horizontal mill, that's like putting a ferarri engine on a lawn mower. Amusing, but surely you have better uses for your money.
 
A compatible servo drive. Technically any good servo drive of the right power rating could be made to work, but a Yaskawa drive would likely have pre-loaded motor data available in programming by a look-up table using their part number, otherwise you will have to gather and load a lot of motor data into it yourself.

That said, if you don't already know all of this, you might be biting off a little more than you can chew. Servo drives are way more complex than basic VFDs.
I think he just wants to hook up the U,V,W and ground wires to a VFD and leave the encoder unplugged. Remove the brake if so equipped.

The servo motor is probably something he has laying around. I see fairly large servo motors (non Fanuc) get thrown in the scrap bin all the time due to our maint not wanting to dick with repairing a dead encoder.
 
I don't think servo motors work with regular VFD drives. They are permanent magnet motors, so they need some additional logic to run.
 
Quite a number of VFDs these days will work with a PM motor. It might be fine.... Unless it is an odd voltage, has very special connections, etc, which it might, it should work as a dumb motor OK. It just won't do all its tricks.

Problem is, many are set up in odd ways, to get high rpm.....Like low voltage windings with high voltage insulation, so you can run them at umpty-bump overspeed at nameplate volts, but they won't take plain 50 or 60 Hz at nameplate voltage.....
 
I think he just wants to hook up the U,V,W and ground wires to a VFD and leave the encoder unplugged. Remove the brake if so equipped.

The servo motor is probably something he has laying around. I see fairly large servo motors (non Fanuc) get thrown in the scrap bin all the time due to our maint not wanting to dick with repairing a dead encoder.

This is pretty much where I am coming from, it is not the highest best use but, the motor is compact and has a high power density. There is no brake on the motor, it turns easily so I wonder about it being permanent magnet?

Steve
 
IME, servo motors are the dogs danglers.
I will never use anything else in the future, and am changing my VFD for a servo.

Running an expensive servo will need an expensive electronic drive - or a good one from someone else.
I have no idea who makes a good compatible generic servo drive.
The Y* might have proprietary stuff in it .. or not.
 
I think he just wants to hook up the U,V,W and ground wires to a VFD and leave the encoder unplugged. Remove the brake if so equipped.

The servo motor is probably something he has laying around. I see fairly large servo motors (non Fanuc) get thrown in the scrap bin all the time due to our maint not wanting to dick with repairing a dead encoder.

I don't think servo motors work with regular VFD drives. They are permanent magnet motors, so they need some additional logic to run.
That's the issue. Even without the encoder, the circuit equivalency for a PM servo motor is very different from an AC induction motor, which is what the VFD is going to be looking for. In V/Hz mode, maybe, but performance is not going to be that good.

Quite a number of VFDs these days will work with a PM motor.
Yes, but not the inexpensive ones.
 
Servo to redneck DC generator...

I see fairly large servo motors (non Fanuc) get thrown in the scrap bin all the time due to our maint not wanting to dick with repairing a dead encoder.

I know you can make old servo motors into generators, well, just for shits and giggles, I asked maint for that dead servo motor. Here you go. Cool. :D

Servo is a Yaskawa 1.8 Kw, 19 AMPS. I pulled it apart to check out the magnets on the rotor and sure enough, these things are pretty powerful. The stator had that familiar dead motor burnt winding stink, but it was not that strong. I checked continuity and all the legs were the same and none were shorted to ground. No, I did not use a megger as it probably would have failed that test. Windings seemed ok, so I reassembled it to start the fun.

I kept the guts out of my old dead Mitsubishi 3.7Kw VFD from the Mazak. I used the input 3ph rectifier to change the A/C to DC and used it for experimentation. I used a cordless drill at first, but it did not have the ass to spin the servo with any real load, so I switched to my 1/2" Hitachi which tops out at 700 RPM.

Free running, I got it to put out 80 volts. I then hooked up a ammeter to get direct DC current reading while I had my Fluke meter checking one leg of the A/C side. I got some pretty interesting results. I was able to get 25 AMPS out of the rectifier. :eek: The wiring was getting hot as well.

Anyway, probably the best use for the 5Kw servo is throw it on Craigslist or ebay because someone will take it--even if the encoder is shot and no longer good for CNC use, then as others have said, score a cheap 3ph motor for your mill. :)
 
That's the issue. Even without the encoder, the circuit equivalency for a PM servo motor is very different from an AC induction motor, which is what the VFD is going to be looking for. In V/Hz mode, maybe, but performance is not going to be that good.


Yes, but not the inexpensive ones.

That depends on what you call "inexpensive".... And it should be changing, because at the end of the day, it is PROGRAMMING that makes the drive PM capable.... There are more PM motors showing up, so the capability will be making its way lower on the food chain.
 
Hem's sake, JST. This is about a specific servo motor.

If you won't recognize that Jraef knows whereof he speaks, wyncha look up the characteristics of the particular beast in question - AND the Yaskawa Servopack drive for it - before you add any more ignorance or irrelevance to the pile.

:(
Bill

What's with that?

We were talking about "in general' PM motor capability..... I commented that it's becoming more common, and his comment was "not in low cost drives".....

My last comment was that there are more PM motors, and I expect drives will soon follow with more having PM capability... I think that because likely people won't want as many non-PM capable drives as PM motors invade common usages. That really depends on how the magnet issues shake out....

As for a SPECIFIC servo motor, and a SPECIFIC drive matched to it, that's a different matter, and if you want to get out of the servo motor all it can do, you want the drive that goes with it..... that was designed as a system with it.... And, if you have that drive, you want that motor, ditto.... In some cases you may HAVE TO have it.

As for programming..... it's true..... the drive company that I am associated with (we have an agreement with the US distributors) has essentially identical drives which are specific for applications due to PROGRAMMING..... yes, there may be some differences in sensors within the drive, of course, but not a lot, actually. The PM capable drives are virtually the same as the non-PM capable other than programming.

As for the servo, it is a PM machine, and therefore can be operated as a PM machine if the drive can handle the voltage range and current, and is PM capable. It won't do all it's tricks, but it will spin and be controllable, in most cases. There are some motors that are so specialized that they just are not much use outside their application, and without their specific drive.

That is a long way from suggesting that "any" drive can be just willy-nilly substituted for the designed-as-a-system drive matched to the servo for the application.....

You may have noticed that I wasn't very positive even on using a servo in place of a regular motor..... That subject has probably been thrashed sufficiently in this thread.
 
not getting into ice-bergs(sp?) here's the real scoop

1) you will NOT find a generic vfd to buy that will run that motor under load
2) That "17bit" encoder is unique to Y and useless to ANY non Y. drive so IF you want to pursue this, plan on buying and adapting a generic encoder on that motor AND buying a SERVO drive to run it.
3) it would be dandy to use as a windmill generator mounted hi on a tower with about a 10ft diam blade, but useless for a motor of any kind on on a generic vfd.
4) buy a matching Y. brand SERVO drive to run it and you will have a damn good spindle.

PS: google SYNCHRONOUS MOTOR and INDUCTION MOTOR and pay close attention to the discussion on SLIP and 0 slip of a synchronous motor. these things make all this discussion useless; it won't happen.
 
PS: google SYNCHRONOUS MOTOR and INDUCTION MOTOR and pay close attention to the discussion on SLIP and 0 slip of a synchronous motor. these things make all this discussion useless; it won't happen.

Not arguing for that particular motor, but what does the above statement mean? What do you mean "won't happen"?

PM motors are synchronous, and some VFDs have the programming to run them. If a drive has the programming and parameter range to run any particular motor, whatever the name and ancillary equipment on the motor, the drive will spin the motor. Likely there will be some motors so odd that practical generic drives won't deal with them.... OK, that doesn't make it true of all.

The oddness of the motor determines how useful the combination will be. As a spindle motor, the drive /motor combination is designed to do a specific job, and I would not expect it to do that as driven with the vast majority of other drives. Without the ability to deal with the feedback from whatever position encoder is on the motor, obviously the drive will have very limited functionality if you wanted to use it AS a spindle motor, unless you give it the drive designed for it.

But I'd expect at least some other drives to be basically able to spin many spindle motors and make the motors do the tasks of an induction motor, possibly doing them better than an induction motor.
 
Not arguing for that particular motor, but what does the above statement mean? What do you mean "won't happen"?

I was perhaps a bit to harsh with that comment. You are 100% right of course that running a PM motor on a VFD is just a matter of proper programming.

That said, and tempering my next comment with "in my experience," I do not believe there is a generic vfd drive available that will run a PM motor without stalling, thru 0 to 200% - heck 0-50%- load change - without feedback. And, NO sensorless vfd for load changing pm motor. Even most washing machine PM motors still have halls. Yes there are specialize buried magnet PM motors and special matching sensorless ICs to run them, but a spindle is not a washing machine and quick load changes of any kind knock a synchronous motor out of synch w/o feedback.

So if OP were to take the time and cost to replace the encoder, he obviously could try to run it with a cheap $400 vfd with encoder feedback control. After many many hours of tweaking parameters, he will likely not be happy with the result, from my experience. Or he could do as I suggested and spend $ 600 on A SERVO drive, plug it in, set some parameters and in 10 minutes have a good servo system.
 
I was perhaps a bit to harsh with that comment. You are 100% right of course that running a PM motor on a VFD is just a matter of proper programming.

That said, and tempering my next comment with "in my experience," I do not believe there is a generic vfd drive available that will run a PM motor without stalling, thru 0 to 200% - heck 0-50%- load change - without feedback. And, NO sensorless vfd for load changing pm motor. Even most washing machine PM motors still have halls. Yes there are specialize buried magnet PM motors and special matching sensorless ICs to run them, but a spindle is not a washing machine and quick load changes of any kind knock a synchronous motor out of synch w/o feedback.

So if OP were to take the time and cost to replace the encoder, he obviously could try to run it with a cheap $400 vfd with encoder feedback control. After many many hours of tweaking parameters, he will likely not be happy with the result, from my experience. Or he could do as I suggested and spend $ 600 on A SERVO drive, plug it in, set some parameters and in 10 minutes have a good servo system.

If I could source a 600.00 servo drive for this motor, I would buy it. I was intentionally vague in my first post. While I know some VFD's "could" turn a PM motor, my primary quest was other options than a matched sevropack. The servopack for this motor is the best choice without question, the cost is prohibitive for my use.

Steve
 
Sittin' here wondering how to break all this news to my Permanent Magnet motors.... I mean .. they left the factory having been promised a diet of Direct Current.

Oh well... maybe I can wire 'em up to a JST Drivel Drive and go chasing after moonbeams?

Bill

Or, if you are less interested in just saying "no" all the time........ And you are talking about PM AC motors.......

You could try the drives from for instance, Invertek (P2 series), which DO run PMAC motors.... and give good open loop (sensorless) control, as well as the capability for feedback control, with internal PID.

As Mike Kilroy says, you are NOT gonna get the full performance out of them available with the proper drive. Why would you expect to?

But if you need to run the motor in a less demanding application than an advanced machine tool spindle, you can do pretty darn well.

Incidentally, in case it has escaped your notice.....

PMDC motors, of any type, commutator to hall sensor types, can ONLY work by internally converting the DC to what is effectively AC....... Either by appropriate electronic pulsing, or, with a commutator, by switching the direct current to new coils, which is a mechanical way to do the same thing. So even a PMDC motor is, inside, a PMAC motor...... of course you may not be able to use it with AC, due to specialized construction, etc.
 
Amazing.

But drive on!

'Nuther 500 lbs of irrelevant bullshit oughta fertilize the pear trees for another year or three.

Meanwhile ... those in the know will continue to drive DC motors with DC or DC Drives, AC motors with AC line or VFD, steppers with stepper drives, servos with servo drives.

It's wot actually works. The 'real world' dasn't put much stock in your messy mental masturbation.

Thankfully.


Bill

Bill, get with the program.....

I know it's my own post you are getting all fluttered about, so I am intentionally not getting heavy-handed......but if you continue to get offensive for no reason here, guess what?

it's gonna be post deletey-poo for you.....

Or maybe it would be more effective to leave your posts up, since they are making no sense....

meanwhile, you might decide to read a few things before pulling the trigger with no primer in the cartridge

A) the thread title " AC servo as spindle motor drive"

B) your own quote of the OP that indicates its an AC servo.....

C) Mention of "as long as you are talking about PMAC motors"......

maybe you got stuck somewhere in the DC drive thread? Or maybe you do not think the OP knows what he has.....

I found very little about that servo... nothing even at yaskawa, unless the model number is a mistype
 








 
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