General > General Technical Chat

How Does the Dyson Motor Work?

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Cyberdragon:


He apparently doesn't know either. From a link in the comments that led to one of Dave's early rants he shows the box of an early model dyson cordless vacuum. On the box it clearly says "neodymium magnets" meaning it's a brushless DC motor. But in this motor from the hair dryer there is a magnet, but it's not neodymium because it was weak. I doubt a DC motor would work very well with magnets that weak without something else going on. He says it could be a reluctance motor, but then why have any magnets at all? Are they some sort of "easy-start" thing? :-//

rob77:
it's a 2 pole brush-less DC motor.. it has only 2 poles to get the high RPM (the more poles it has the slower it goes at the same switching frequency).

Cyberdragon:

--- Quote from: rob77 on October 22, 2016, 08:09:49 pm ---it's a 2 pole brush-less DC motor.. it has only 2 poles to get the high RPM (the more poles it has the slower it goes at the same switching frequency).

--- End quote ---

Are you saying they are getting 100W of power with a magnet no stronger than a fridge magnet?

bktemp:

--- Quote from: Cyberdragon on October 22, 2016, 08:21:36 pm ---
--- Quote from: rob77 on October 22, 2016, 08:09:49 pm ---it's a 2 pole brush-less DC motor.. it has only 2 poles to get the high RPM (the more poles it has the slower it goes at the same switching frequency).

--- End quote ---

Are you saying they are getting 100W of power with a magnet no stronger than a fridge magnet?

--- End quote ---
I don't see why not. That motor does not need to generate a high torque, it is optimized for high RPM.

rob77:

--- Quote from: bktemp on October 22, 2016, 08:30:29 pm ---
--- Quote from: Cyberdragon on October 22, 2016, 08:21:36 pm ---
--- Quote from: rob77 on October 22, 2016, 08:09:49 pm ---it's a 2 pole brush-less DC motor.. it has only 2 poles to get the high RPM (the more poles it has the slower it goes at the same switching frequency).

--- End quote ---

Are you saying they are getting 100W of power with a magnet no stronger than a fridge magnet?

--- End quote ---
I don't see why not. That motor does not need to generate a high torque, it is optimized for high RPM.

--- End quote ---
exactly - the strong magnetic field would be needed for torque not power... i would say the weaker magnetic field is even better to get the very high RPM the impeller needs to move that air volume.

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