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Old 09-21-2013, 10:22 PM   #379
rusty959
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Join Date: Jun 2012
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Quote:
Originally Posted by wulfgang View Post
This is an interesting topic. I'd like an electric supercharger for DE days, but the math doesn't work out for a lap-averaged energy draw (the alternator doesn't make enough power even if it operates at 100%). A really good alternator might be able to give 2 kW average power, so if you are on the throttle roughly 50% of each lap, then you have a max of 4 kW to drive a supercharger. So not very much.

With regard to the gears, keep in mind that some superchargers are gear-driven and they have a lot of gear whine. Then there are belt-driven units that can be unreliable because of the belts.

...and then there is Rotrex, with their cool non-newtonian fluid in a planetary traction drive. If you had the money to fabricate parts to direct drive a Rotrex, then your electric motor options would greatly increase because you could drive at 10-15 krpm and still have the compressor wheel turn 90 krpm. None of the other superchargers even come close to this speed, so it seems likely that a complex Rotrex-like traction drive is necessary to get such speedups on the drive.

You might also want to look at sourcing the compressor wheel from a supercharger rather than from a turbo. Although in principle the wheels should be equivalent, it seems like the supercharger manufacturers get the maps that have the plateau a lower speeds.
Driving a supercharger is not a bad idea. It would definitely be easier to setup, especially since max motor speeds tend to go down as you use larger motors. The main reason I have stayed away from them is the great cost difference between a turbo compressor housing/wheel and a supercharger. But, by the time everything is all said and done, I might could have picked up a rotrex or something. Ill be looking at it more before I buy too much more stuff, for now I'm just doing testing of how well brushless motors run together (ill be making another post on this soon)

I appreciate the transistor tech knowledge. I think at the moment none of us are trying to make our own brushless motor controller, its just added complexity I don't want to deal with when there are off the shelf options available.
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