Electric Superchargers?

[DGthe3]

I am looking for ideas for a design thesis and I was wondering what anyone knew about them. I am considering making a programable boost controller for one that can be adjusted on the fly, and even turned off completely when not wanted. Does anyone here know if something like that exists? Thanks

[Mr. Wyndham]

Oh, they exist alright.
link

I don't think I'd ever buy one, though...the power required to move any substantial amount of air, would probably be a large enough quantity to drain the battery. But for a quick little oomph, on a small little engine, they're good enough, I suppose.

Lemme know how your controller works out, it could be interesting.

[DGthe3]

Originally Posted by Dragoneye

Oh, they exist alright.
link

I don't think I'd ever buy one, though...the power required to move any substantial amount of air, would probably be a large enough quantity to drain the battery. But for a quick little oomph, on a small little engine, they're good enough, I suppose.

Lemme know how your controller works out, it could be interesting.

I knew electric superchargers were out there and would only work on small engines, but I don't think there are any where you can dial it up while on the move. From the looks of it, the ones in the link you posted have an on off switch, but no 'boost dial'. That would be the feature that I come up with

[Mr. Wyndham]

Ooooohhhh. I thought you wanted to know if they make electric superchargers so you can modify one....

[BigEnos]

Someone asked CarCraft about electric superchargers and they pointed out that B&Ms test rig uses a three stage AC electric motor to test run their superchargers at no load. Given that B&M haven't been peddling crap all these years and they do make a product that is reasonably efficient, I'd say that's a lot of power to spin that blower to normal running speed, and that's even before you add a load (IOW actually build PSI). To install that size electric motor and the wiring/power generation infrastructure to run it would be counterproductive if not impossible.

If you are looking for nearly free and adjustable power, turbochargers seem to fill that bill nicely. It's not easy, but it's been shown time and time again that it works.

As another "data point", Mercedes Benz installs clutched pulleys on its superchargers and they do shut themselves off at low/no load.

[Mr. Wyndham]

Right, Big Enos. I first saw those on the market...and thought; dumbalot?

But for a design thesis :p I think using an electric supercharger should be fun.

[SilverTurtle]

I believe Mercedes uses an electric clutch on some of their superchargers to make it where the car doesn't have to be in boost all the time... there is a series of butterflies that operate in conjuction with the electric clutch to channel air either straight to the engine or into the supercharger plenum when the electric clutch is engaged.


for a thesis, why not modify this type of design into a more straight forward MagnaCharger design with variable vains that can be adjusted via rheostat and resistance/current... this would be, essentially, a supercharger version of the variable vain turbos.

but, then again, this comes from a mechie who has more free time at work than fabrication time at the house

[Power Junkie]

There are electronic boost controllers on the market which allow you to set up different boost levels so you can change at the touch of a button... GReddy, Blitz, Apexi, HKS all do them... basically they work on the waste gate.. however i've not heard of people using these with superchargers.

BTW electronic superchargers... are in a word crap.....

[Angrybird 12]

Being an Electrical Engineering Technician, and Knowing what I know about Turbochargers, the speed you would need to turn the turbo would require a step up gearing to increase the speed from what the electric motor produces to provide sufficent boost. Being that it would take probably a few (1-5maybe) horsepower motor to get that kind of speed. that would increase weight and drain power from the battery requiring a bigger or aux altenator along with a secondary battery.
I would say the effiency is not there, you would be better to just go with a real turbo. simplier, more bang for the buck and less power robbing...

The electric turbo chargers I have see are no more than a fan to blow air into the intake, virtually useless.

[LSxcellent]

As a data point... it takes 125hp to run the supercharger on a Mustange GT500 at full boost.

Just to put that in perspective, that is ~93,000 watts. If you assume you are running your motors at the cars nominal 12v, that means your motor will be consuming about 7750A. The BIGGEST batteries I can find have about 55Amp/hours of capacity, and since your battery would be supplying most of the power required to run the supercharger (your alternator would die or stall the engine if it had to supply this) you can expect about 25 seconds of runtime at these power levels.

You can use this math to extrapolate how much runtime/power you'll get, but all in all its not much.

Also keep in mind the energy-transfer-efficiency rule... everytime you change the 'flavor' of your power, you lose some to efficiency. So in your case, you are taking the mechanical energy of the engine, turning it into electrical energy with an alternator (loss), storing it in a battery (loss), turning it back into mechanical energy with a motor (loss) and then compressing air with it (big loss).

A regular supercharger just starts with mechanical energy of the engine and compresses air with that... much less overall loss and better efficiency.

Turbo's actual take advantage of the hot-expanding-exhaust-gas (which is otherwise wasted energy) and they capture this 'waste energy' and use it to compress the air (overall better efficiency again).

If I were you... I would do this:

-Start with a turbocharged system (best overall efficiency)
-Use your electric supercharger idea to make a 'zero lag' system. Something that spins the turbo up to speed in no time.
--You can use an extra fan on the exhaust blades to spin it up (idea 1)
--You can mount the electric motor to the turbo-axle and spin it directly with the electric motor (probably requires some gearing and a one-way clutch) (idea 2).

This way you have the boost-response of a supercharged system with the overall efficiency and power potential of a turbo-charged system.

FYI, I make military robots, so I've done a LOT of work with motors/gears/efficiency calcs etc. Feel free to ask more questions!

~LSx

[DGthe3]

Originally Posted by Power Junkie

BTW electronic superchargers... are in a word crap.....

I figured as much since they weren't very common, since they are inherently less efficient, 2 energy conversions vs 1, coupled with the fact that they can't provide very high flow or boost because of the batteries. The alternator would need to get upgraded if the system is used for any amount of time, and that adds back the parasitic loss that you just took away by using bateries. Also, even some of the biggest that alternators that I could find provide about half the juice needed to run the the supercharger for 2.0L ecotec's.

Taking all that into consideration, I have come to the conclusion that using an electric motor for constant forced induction simply won't work. Thats where the on/off switch comes in, as well as the boost controller. Something like this would only be used in street applications.

LSxcellent, I would love to do what you suggest, but they don't quite fit into what I need to do. This is for my engineering design thesis and I am taking the mechatronics option for mechanical engineering. Basically that means that I have to incorporate programing and electronics into some mechanical application. I may be able to do it, I will have to talk to faculty members to see if I am allowed

All in all, it looks like it may still be possible to do something with this but I only use it as a back-up idea. Thanks for all the input

[Mr. Wyndham]

You know...if anything, couldn't you argue a lawn-mower application for this project, DGthe3?:p
I'm serious, those tractor lawn mowers have "alternators"...and they only produce 20ish hp, so bumping that up wouldn't require massive amounts of air.

But Good luck anyway you go! It should be fun.

[stovt001]

LSxcellent: ^ That's brilliant.

[LSxcellent]

Originally Posted by DGthe3

LSxcellent, I would love to do what you suggest, but they don't quite fit into what I need to do. This is for my engineering design thesis and I am taking the mechatronics option for mechanical engineering. Basically that means that I have to incorporate programing and electronics into some mechanical application. I may be able to do it, I will have to talk to faculty members to see if I am allowed

All in all, it looks like it may still be possible to do something with this but I only use it as a back-up idea. Thanks for all the input

Yup. This is what I thought... my degree is Electromechanical Engineering (double in Electrical & Mechanical). I know exactly what your up against... I had to do a very similar design thesis for my program as well.

Just to put a bug in your ear... think of my idea this way:

-The mechanical aspect is the electric motor & gears that drive the turbo
-The electrical component is measuring injector duty cycle & throttle position or designing a circuit to do this from the outputs of the ECU
-The programming is setting the turbo-spool-up program into the motor controller so that the turbo spools up at the correct rate for the throttle position and speed, as well as custom tuning to the engine ECU.
--You could also set this up as a 'user selectable' boost system, where you could map the turbo wastegate, turbo-spooler, etc into a seperate controller.

Just tossing ideas your way...

~LSx