powerful stepper /brushless motors up to 12Krpm 750+W

[Simon]

I'm looking for stepper motors and controller if available capable of 750W of power and up to 12'000rpm @ 28V. Is this something that can be obtained easily or do they tend to be bespoke made ?. We don't need many so having stuff made is a bit of a non starter. Potentially we could look at a controller that will bump the voltage up say 2x if it's customed made or available in order to get what we want.

Can anyone recommend any particular manufacturer / supplier ?

[Simon]

yep. We could use a belt to increase speed.

It's not fast, your hard drive motors do up to 15Krpm and the dyson air blase hand driers have a 90Krpm motor in them.

Is stepper the correct name ? we need speed and power with no brushed, positioning accuracy is not a problem.

[Simon]

So what is the difference between a brushless and a stepper ? my recent investigastion seems to show that "brushless  motor" just describes a stepper of some sort + a controller.

So where do I get a brushless motor with these abilities?

[Andy Watson]

15k RPM stepper would be some motor, especially at 750W. I think the term you are looking for is "spindle motor".

[Simon]

two caveats, reliability is of the upmost importance. I see funny looking specs when i look at RC motors that remind me of things like the laughable PMPO ratinmgs of compter speakers.

I need reliability and peak power for prolonged periods so not something thats made to give a shot of thrust and then rest for a while.

[Andy Watson]

Put "spindle motor drive cnc" into your favourite search engine.

[Simon]

And if you read the brushless motor page it describes a stepper type motor with built in controller and says about as much:

"Brushless motors may be described as stepper motors; however, the term stepper motor tends to be used for motors that are designed specifically to be operated in a mode where they are frequently stopped with the rotor in a defined angular position. This page describes more general brushless motor principles, though there is overlap."

Yes a stepper can be specifically positioned and is used for that sort of precision, a brushless will usually be controlled to just turn. "brushless" motors I have seen driving fans actually index and go through a setup procedure before they will run because they have a built in procedure. They usually index to work out the position they are in and check that the fan is not obstructed before starting up full power. I would assume that brushless motors have much few steps than precision positioning stepper motors.

[oldway]

Why "brushless" ?
As you can use a belt to increase the speed, what about a very reliable vacuum cleaner motor?
I mean a Nilfisk GM80C motor....power is hight, 1300W but need force cooling. No problem to reach 750W.
Workt on 240Vac (also on 240vdc).
I do'nt now how much rpm, but it is high rpm. You should ask this information to the manufacturer.
You should use a dc/dc converter 28/240V if grid is not available.
And a rpm sensor for rpm regulation.
A Mc Gijver solution.... 

[Simon]

Yea, I'm a bit like Mc Gijver around here, always end up being asked at the last minute to see if I can fix it. I did suggest a vacum motor but power is the problem. I think we may have emi problems too.

[G7PSK]

Try this company.

http://www.sem.co.uk/products/

[SeanB]

What you want is basically a 3 phase squirrel cage motor (regular one without brushes) that will have a drive from an inverter that typically has a mains input and 3 wires to the motor.  You having to run from 28V means either you are looking at trucks or aircraft, and are looking at a custom wound 400Hz 3 phase motor and a drive system to power it. You can get IGBT modules that will handle the 40A or so current draw that the motor will need, and there are a lot of VFD inverter drive chipsets around that can do the PWM drive. You just need to join the dots, but the drive is going to be a fairly big chunk of heatsink with a board attached as an afterthought. Probably about the size of a loaf of bread.

Is it not possible to use a series wound, shunt wound or permanent magnet motor with a tacho pickup and a speed regulator? A 24V one will likely be an off the shelf item from a motor manufacturer like Bonfiglioli, WEG or one of the other motor manufacturers.

[Simon]

I think i might have to ask more questions about what is actually required. My aim is to have the 10-12000rpm as we are using a belt and pulleys at the moment which I'd like to avoid (recovering some cost for a better motor solution). It's land vehicles btw.

[Rufus]

So what is the difference between a brushless and a stepper ?

Steppers are usually 200 steps per rev, brushless DC motors usually 3 so the difference is usually 197 poles.

[Simon]

Right, I was unclear as to actual construction of the raw motor before it has a controller, however any combination is possible i guess.

[NiHaoMike]

What about a large model aircraft motor? Just derate it for continuous operation.

The fastest motor I'm aware of in a consumer product is a water cycle air conditioner compressor that runs at up to 100kRPM, but that's a switched reluctance motor.

[Simon]

I'm just concerned that model aircraft motors will not have the durability and reliability, this motor really really must not fail.

[Kremmen]

I'm looking for stepper motors and controller if available capable of 750W of power and up to 12'000rpm @ 28V. Is this something that can be obtained easily or do they tend to be bespoke made ?. We don't need many so having stuff made is a bit of a non starter. Potentially we could look at a controller that will bump the voltage up say 2x if it's customed made or available in order to get what we want.

Can anyone recommend any particular manufacturer / supplier ?

It is not something you can get at all, never mind easy. A stepper like that is not obtainable for love or money. Nor would it make any sense or be in any way the right choice for such requirements. Steppers are generally used in low performance positioning applications and similar. And in any case, 28V would not be nearly enough to force feed a stepper to the astronomical step rates required for such a shaft speed.
The real killer is the low voltage. Cetain kinds of brushed DC motors can do RPM like that on such a low voltage, but then you might be against the reliability requirement. If it "really, really" must not fail, then your best option is a 3 phase induction motor or AC servo. Only AC servos generally do max 3000 or in extreme cases 6000 RPM and induction motors no more than 3000 or 3600 RPM. But insert a 200 Hz capable inverter drive into the equation and you can do your 12 kRPM with the right motor. Unfortunately it won't do it with 28V.

What you need to do is put your requirements in priority order. Fulfilling all of them could become awfully expensive, but fulfilling the most important 50 to 80% could be manageable.
Others have included useful links to mfgs that make motors in the categories i mentioned above. The solution, if any, will be somewhere in that bracket

[penfold]

It does sound like a bit of a custom job.  There is a company in the UK called Controlled Power Technologies (CPT) who make some high speed and high power motors for automotive super-chargers, so these will also have with them a pretty descent reliability, could be worth contacting them.

[Simon]

What you need to do is put your requirements in priority order. Fulfilling all of them could become awfully expensive, but fulfilling the most important 50 to 80% could be manageable.

Well my priorities are:

1) power - without it nothing will be happening

2) voltage, I don't think we want to be using inverters as we are mechanical not electronic so the very idea scare them

3) speed - being a mechanical company we will use gearing

Personally I'd swap 2 and 3 but my boss will have it as above. I can't see much wrong with setting a target for 46V using a voltage doubler off a H bridge.

I'm not neccessarily after fine step steppers but something that can be controlled to do what we want.

As for it being near impossible we already have a motor that does the power and voltage but it needs gearing up and it was not really designed for what we want so stalls on startup as it does not expect the mechanical load we are applying to it and has it's custom controller hence me seeing this as a two part thing, motor (of whatever type you care to call it) and driver.

[Paul Moir]

You're not gonna generate motor power with a doubler.  Forget that.

I don't think you say how much power you need, but if it's outside of a dremel motor than it's not going to happen with 28v.  Motors are inductors and you need voltage to get power into it at high speeds.

I think someone mentioned aircraft motors.  By which I think he means 400Hz proper aircraft motors.  That is a good McGuiver idea as they're small high speed items and you might be able to find an old one cheap.   

10-12K rpm means 10k right?  If you mean 10rpm it's gonna be a brushless servo motor.

[Simon]

like i just said we have a motor that is 750W at 28V but it's not setup to run with the type of load we are giving it so stalls on start thinking that it's jammed because we cut it out of something else and adapted it

i have seen a number of motors rated to 48V already


it's 10K - 12k I'm after, although the power is more important than the speed

[Paul Moir]

Oh sorry, but I think that shows the point about the doubler:  750/28 is a lot of current to make with a doubler.

How fast does your current motor spin?  To spin it twice as fast with the same torque should be twice the power then right?

PS - Hard to beat aliexpress sometimes!  Check out this: http://www.aliexpress.com/item/1-5KW-Water-cooled-spindle-motor-220V-ER11-24000rpm-3-bearing-1-5kw-Inverter-VFD-2HP/1252450743.html 
(Just googling around..)

[Simon]

I think the current one is around 2500-3000rpm so we have geared it up, the torque is there but it was used before to drive a light plastic fan, now that we have connected it to a pulley and belt it sort of gets confused and is fussy about starting so i suggested we get something setup properly.

[Rufus]

2) voltage, I don't think we want to be using inverters as we are mechanical not electronic so the very idea scare them

The electronics to drive anything but a dumb brushed DC motor from a 28v DC supply is going to be as complicated as an inverter anyway.

I think your choice is limited to brushless DC which which you might be able to get at 15k rpm and 28vdc drive (but how well does it have to perform when your 28v is only 22v?) or 3ph induction.

You can get 2 pole 3ph induction motors good for 15k rpm which requires 250Hz drive which is available from some off the shelf 3ph motor drives. Some 3ph drives can be fed around 350vdc instead of 120/240v single phase ac. You would need a 28v to 350v DC-DC converter (at more than 750W).

http://www.groschopp.com make a lot of motors - much more than gets listed on their web site. I know they do 2 pole 3ph motors good for 15k, don't know if they go up to 750W with them.

[peter.mitchell]

I think the current one is around 2500-3000rpm so we have geared it up, the torque is there but it was used before to drive a light plastic fan, now that we have connected it to a pulley and belt it sort of gets confused and is fussy about starting so i suggested we get something setup properly.

Does the unit use a controller? (I assume it does) The controller probably has an expected startup RPM curve, so when you change the load, the RPM curve does not match and it changes poles too quick/slow - either that or it goes failsafe.

A lot of controllers in the RC world instead of following a fixed curve, use inductive feedback from the motor windings to measure RPM and advance/retard the timings of pole changes appropriately, because in the RC world, any man and his dog can put this stuff together, with random gearing (and load), motor and power supply selection.

Either change the curve or change the startup method.