Motor for 75000 RPM 1

[Alex32410]

Dear colleagues,

We have designed compressor for 75000 RPM and 1,5kW, but now have difficult time finding motor supplier.

Please, can you suggest high speed motor manufacturer.

Thank you in advance.

 

[BrianPetersen]

Regular motor and a step-up planetary gearbox. You are nearing automotive centrifugal-supercharger specifications, and that's how they do it.

(Was this whole project not thought through before committing to the design?)

 

[GregLocock]

http://www.atzonline.com/Artikel/3/...ormance-of-Turbo-and-Compressor-Charging.html

Cheers

Greg Locock


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[jraef]

If trying to go with AC, you have a problem. N = 120f/P where N = Synchronous speed, f = frequency, P = number of poles. So since you can't have fewer than 2 poles, 75,000 = 120f/2, so f = 1250Hz. You can get VFDs that will put out 1000Hz, but I've never seen one that goes up to 1250Hz.

That said, I have run across a turbo blower mfr that claims they run their blower at 1250Hz, and in looking at their brochure, the photo of the VFD inside of the box looks to be a Vacon product.

http://www.hsiblowers.com/downloads/High-Speed-Turbo.pdf

I looked at Vacon's spec sheets and they don't list an output frequency higher than 320Hz, but it may be a special version that they build for this OEM. You might try to call them and see if they will share that info with you, but if you are going to be competing with them, don't count on it.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[redlinej]

Hello,
Are you sure its 75000 rpm and not 7500 rpm.If it's 7500 rpm you can use a VFD and double the frequency and size the motor within it field weakening range.

 

[Alex32410]

yes, I am sure, we need 75000 RPM, but it is very hard to find, even with gearbox increaser.

 

[tygerdawg]

I'm no expert on compressors so I'll risk the appearance of an ignorant moron with my response. At 75,000 RPM I would think you would have bigger problems than finding a suitable motor & drive. It seems to me your primary concerns would be bearings and how to keep them cool enough so that they don't expand and seize, then how to design & fabricate the impeller blades etc. so that the centrifugal force doesn't turn them into shrapnel because of fatigue failure.

75K RPM will produce a prodigious amount of rotational inertia. I've worked at two places in my career in which a large process compressor and a large process vacuum pump both were spun at much less speed (range of 10,000 to 15,000 RPM), failed due to mechanical issues, and the workday became very...exciting.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[BrianPetersen]

Automotive centrifugal superchargers are in that RPM range and that power-demand range. The one that's in a vehicle that I own (a Kawasaki H2) uses a planetary speed-increaser with an 8:1 ratio, and the entire drive mechanism for it is inside the crankcase so it is flooded with ample lubrication. Here's an aftermarket one intended to be driven by an accessory belt and which contains its own integral oil supply:

https://www.procharger.com/centrifugal-supercharger

 

[GregLocock]

28 years ago I worked on an alternator that was direct drive from the turbo on a passenger car, which spun at 120000 rpm. This stuff is not rocket science.

Cheers

Greg Locock


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[GregLocock]

Here's another option

http://www.celeroton.com/fileadmin/user_upload/produkte/motoren/datasheets/Datasheet-CM-25-280.pdf

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[mikekilroy]

jraef, just for reference, we have hi speed nitrogen compressors running at 50krpm in 30hp range, 24/7, at some petro plants around the USA with our 3000hz max output Refu vector drives (refu.com). these use magnetic levitation bearings.

we also routinely sold many 3000 hz output v/hz drives during the great USA machine tool market in the 70's thru about 2000 - mostly for high speed grinders. We seldom need over about about 1666hz anymore today, but Spindel (aka old Volkmann) still will sell you a very high performance 3000hz drive from 1-300hp today (spindel.com), from stock on most.

As you know, we can no longer supply over, IIRC, 400hz max output for sale outside the USA without ITAR government permission. Those less than friendly countries want them real bad for making nuclear bomb stuff.

So they do exist.

http://www.KilroyWasHere<dot>com

 

[roydm]

I seem to recall the turbo-expander in an Oxygen plant I worked on spun at 30.000 revs