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Thread: Electric forced induction?

  1. #11
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    how does the hybrid rule prohibit an electric supercharger? The electric motor doesnt provide thrust for the car and is therefore more like an electric water pump.

    If you were going to use some thermoelectric generator and a turbocharger you will want to use the generator after the turbine.

    All systems you proposed for generating electric power will be rather heavy and complex. I cant really see the advantage compared to using a battery to store the energy, especially as an endurance is finished in a short period of time. You could also run a bigger alternator on your engine, that is only switched on during overrun. Because of the low power requirement the traction of the rear wheels is not really a problem.

  2. #12
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    What about electric motors for fans, water and fuel pumps, DRS or gear actuators? All electric motors running off stored energy, and totally allowed. How is a supercharger any different?

    Surely the "intent" of that rule is to do with wheel drive or propulsion motors, not any electric motor on the vehicle.

    You can do the same thing with hydraulics as well. Efficiency is about the same, power density of the actuators is much better, but worse for the storage. In the case of hydraulics it is not so versatile to use all over, and transmission is more of a hassle, so I would be looking to harvest from the diff rather than the front wheels. There should still be plenty of energy available even at the back I would think.

    Pete

  3. #13
    Tobias,
    Andrew Deakin may be able to confirm this, but my memory says that the Cal State car ran the supercharger directly off their on-board alternator, i.e. they did not store any additional energy beyond a "normal" battery. Apart from the very limited amount stored in the normal 12 volt battery, all the energy used by the car came from the petrol in the fuel tank. In overall terms, the electric supercharger was treated, by the scrutineers, like an electric water pump.

    Teams that want to build a hybrid should do so. We would love to see them at the Formula Hybrid competition at New Hampshire International Speedway in May each year. Be aware though, that technically, building a running hybrid is an order of magnitude more difficult that an IC or electric FSAE/FS car! The upside is that GM, FOrd, Chrysler and Toyota are there recruiting as hard as they can. If you want a job in the auto industry and are a member of one of the hybrid teams, your chances of employment are very high!

    Michael Royce,
    Chief Mechanical Scrutineer,
    Formula Hybrid.

  4. #14
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    Quote Originally Posted by TMichaels View Post
    A thing that always baffles me is that there is no voltage limit for the electric system of the combustion cars. A 600V system will probably be rejected at scrutineering, but there is no rule prohibiting that.
    Tobias,

    Hmmm, I always thought the spark plugs operate at something like 20,000V (well, that's what it feels like when touching them when the engine is running).

    But that would be a good way of giving the Electric cars a bit of an "unfair advantage" - limit the Combustion cars to 600V maximum!
    ~o0o~

    Harry,

    I reckon the best way of "recovering" braking energy is simply to NOT use the brakes. Good aero, and go around the corners as fast as you go down the straights!

    In the production car world the better solution is to have better roads. Minimal sharp corners, and NO traffic lights (especially at the bottom of hills!!!).

    The only vehicles that really need regen-braking are inner-city buses that have to stop-start all the time to let the passengers on-off. For these I reckon flywheel energy storage is probably the most efficient (was trialled in the 1970s (?), with a 6 foot diameter steel flywheel under the floor).

    Z

  5. #15
    RenM, I do not think that it would be "rather heavy and complex". The total on-board energy that needs to be stored to run all auxiliaries and electric turbocharger would dictate the use of a large capacity (and therefore high weight) battery. Recovering brake energy is a smarter way to charge back your (relatively lightweight) battery than an alternator. Kw-size DC motors are weighting way less than a kilo, so a budget of 2.5-3kg for both motors, controller etc is more than enough. Plus the benefits of brake torque distribution (brake only one motor or both but at different torques to assist steering) and electronic boost control are profound. I don't know if it worth the time/effort (do aero instead :P) but it seems interesting to me!

    Oh, and Z you are totally right...

  6. #16
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    a clever designed electric supercharger wont need a lot of energy during an endurance. Depending on your boost pressure 3-5 kg in batteries will be more than enough.

    Your idea sounds nice in theory but application on the track will be a real pain and is not worth the work for a formula student team.
    Why not simply use a switchable alternator? Same effect, but a lot less complexity.

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