Brushless DC spindle question

[capstar]

I have acquired a 24 volt DC , 600 watt 20,000 RPM brushless spindle motor with a rating of .8 HP and I have no documentation as to what brand it is or the parameters to make it run. The only connections coming from the motor are marked: U, V, and W. I am thinking I am going to need a variable frequency drive to run the motor, Is this correct and will I need anything additional?
So far in looking around the only VFD's I have seen all say their output is in AC not DC.

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[CitizenOfDreams]

"Brushless DC motor" is kind of a misnomer, technically it's a 3-phase AC motor. Normally those motors are used with a special VFD that takes 24VDC and outputs 24VAC 3-phase.

It is probably possible to run your motor with a regular line-powered VFD if you set up the V/F curve not to exceed the motor's rated voltage.

[Al_The_Man]

Is it actually a BLDC motor, if you short the U,V,W and try and spin the rotor by hand, does it resist?
Al.

[capstar]

Is it actually a BLDC motor, if you short the U,V,W and try and spin the rotor by hand, does it resist?
Al.

Yes, I tried that and there was considerable resistance to turning the shaft. I am not totally sure about the 24 Volt spec, the smaller less powerful motor I had says on it's side that it is 150 VDC so I cannot see this one being a 24 volt. A machine manufacturer sent me the motor as a replacement for the smaller motor as a mistake, it is from one of their newer machines and has absolutely zero labeling on it. I agreed with them to keep it and try to retrofit it to my machine since it is definitely a better motor, but since they have new machines they want to sell I have not been able to get them to provide me with any specs other than what they have as spec for their new machine on their site which mentions only .8 HP / 600 watt / 20,000 RPM. The inside of the motor has 6 coil poles surrounding the shaft with a magnet on the shaft there are 6 divisions marked on the magnet around the shaft.

[Al_The_Man]

I have attempted to use a BLDC motor on a VFD with little success.
Normally BLDC or AC synchronous needs some kind of commutation, either by sensors (hall effect etc) or by motor current detection at power up.
That is a very surprising number of poles for a 20krpm motor.
Normally you can detect the number by shorting the stator and turn very slowly and count the 'bumps'.
Al.

[capstar]

The machine I have is one the I-Carvers made in Taiwan, decent little hobby machine, but the spindle motors (4 motors in the last 4 years for me) have been a problem and as a result of that and other problems they have discontinued the machine. Since I have the basic framework it is my intent to modify the machine so that I can keep it functioning, as parts will will become unavailable down the road. I did locate a scematic for the "new " machine that uses this motor, there is no reference to voltage in it either. While there are only the U V W wires coming out of the motor, in the schematic they are showing maybe 5-6 wires coming from the spindle control board and being connected at the top of the motor, how ever there are no connections just a plastic cover plate.

[capstar]

it is my bet that the "other connections might be for the commutation