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Discussion Starter · #1 ·
A Toyota hybrid race car wins a Japanese Endurance race.

3 electric motors including two wheel motors. Super capacitors.

Motors potentially capable of running up to 170 kW-hrs of regenerative
braking.

http://www.greencarcongress.com/2007/07/toyota-hybrid-r.html#comment-76416392

Cliff
www.ProEV.com



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Discussion Starter · #2 ·
> Motors potentially capable of running up to 170 kW-hrs of regenerative
> braking.

Does this sentence make any sense to anyone else? Because it
certainly doesn't to me.

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Discussion Starter · #4 ·
Sorry Zeke,

I can see my note on the part of the article that was of most interest to me
is not only a little cryptic but uses the wrong units.

The electric part of this hybrid uses 3 electric motors that are listed as
being capable of producing a totaling 170 kWs. That is about 227 horsepower
which is pretty impressive. The electric motors should be able to use this
power to slow the car (regenerative braking) and then to accelerate the car.
This is addition to the power that the car is getting from the 4.5 liter gas
motor.

The 'potentially' is there because the Toyota press release (
http://www.newspress.co.uk/DAILY_LINKS/arc_jul_2007/53350toy.htm ) does not
give performance details about the rest of the electric system. How much
power can the motor controllers cope with? How much power can the Super
Capacitors accept?

I would guess that their system is actually utilizing something closer to 40
kW ( 54 horsepower ). I base this on the idea that due to forward weight
transfer under braking, the front wheels do the majority of the braking. The
front wheel motors total 20 kW ( 27 horsepower ) so 40 kW total front and
rear would give an even brake balance.

The flaw in this theory is, 'why run such a massive rear motor?' It could be
the only unit they could find that would survive as part of the driveline.
Otherwise, could they be massivly biasing the friction brake system to the
front to balance the car? Or using some kind of computer control to mix
friction and regenerative braking?

In comparison, the Electric Imp is able to utilize 118 kW or 158 horsepower
of regenerative braking to slow the car. Our motors and controllers have the
theoretical capability of using 237 kWs ( 317 horsepower ) to slow the car
but we are limiting our current into the batteries to 300 amps as we build
experience with the Kokam Lithium Polymers.

Cliff
www.ProEV.com




----- Original Message -----
From: "Zeke Yewdall" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Friday, August 17, 2007 8:05 PM
Subject: Re: [EVDL] slightly OT: Hybrid wins 24 hour race


>> Motors potentially capable of running up to 170 kW-hrs of regenerative
>> braking.
>
> Does this sentence make any sense to anyone else? Because it
> certainly doesn't to me.
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>


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Discussion Starter · #5 ·
On 17 Aug 2007 at 21:27, Brandon Kruger wrote:

> Maybe, they can pull 170 kW from regen?? I'm assuming thats whats meant

I'll bet he meant kiloWatt hours per hour. ;-)

(It's a joke! KWh/h = kW ;-)

I hate to say it, but it looks like the dreaded Units Confusion disease is
ravaging EVDL members again.

You might want to read Edward Ang's rant on this. It'll save me the time
and effort of writing mine again. ;-)

http://www.evsource.com/articles/mind_your_units.php

Remember, when you write a post to the EVDL, it's archived in several
different places essentially forever. Your words are floating round out
there on the web for potential employers to see - and they DO check. Don't
make it look as if you slept through Physics class.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Discussion Starter · #7 ·
TrotFox

> Errr... Massive motor on the rear is to accept massive amounts of
> current during acceleration? In my head the fronts would be of
> relatively little use during peak accel for traction.

That is an interesting idea. So the Super Capacitors takes in 40 kW for 5
seconds of braking. If they then apply the same power as 200 kW for 1
second, that would accelerate the car sooner as long as the car is not
traction limited.

> What kind of power bias do you guys use on the Imp for acceleration?

We have discussed biasing the power to the rear wheels to take advantage of
weight transfer under acceleration and to spare some traction for the front
wheels to steer. In practice, we have found that with running equal power
through the front and rear wheels, we can still set the car up to oversteer
or understeer with springs and bars (and rake and toe, etc.). So for now, we
run no bias.

Cliff
www.ProEV.com





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