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Re: Who Killed the Electric Car?
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I wonder when car manufacturers (including European ones) will finally
wake up. Sometimes I wonder whether they'll wake up at all. A brief look
at Japan might help ...

--
Regards, Joerg

http://www.analogconsultants.com /

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Re: Who Killed the Electric Car?



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Pure electric-only EVs aren't the answer. It'll be HEVs that most likely win
the day.

Graham


Re: Who Killed the Electric Car?
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Hydrogen? Where's that going to be coming from?

--
Regards, Joerg

http://www.analogconsultants.com /

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Re: Who Killed the Electric Car?

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Exactly. My 2c is on a proper hybrid where the ICE(petrol or diesel)
simply runs a generator that tops up the battery bank.

I would really like to see if that works out more efficent that all the
inefficencies of current direct drive ICEs.



Re: Who Killed the Electric Car?
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That's how the Toyota Prius works. Gets between 40mpg and 60mpg
according to what owners told me.

--
Regards, Joerg

http://www.analogconsultants.com /

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Re: Who Killed the Electric Car?
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win
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I was pretty sure the Prius was a parallel Hybrid (the electric motor
was in parallel to the ICE drive train). As opposed to a serial hybrid
where the final portion of the drive train is all-electric.  Some of the
proposed hybrids appear to be of the latter.

The parallel hybrid does mean that neither motor needs to be sized large
enough for the full load.

Robert


Re: Who Killed the Electric Car?
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True, although the Prius is more of a Hybrid-Hybrid:  At low speeds it
is a series hybrid with the majority of the engine power going to a
generator and then to the motor driving the wheels with only a small
amount directly from engine to wheels.

At high speeds the situation is reversed and it acts more like a
parallel hybrid with a large fraction, up to 100% of engine power,
going straight to the wheels.

This is done to maximize efficiency since the mechanical transmission
has an efficiency of 95% or more but the electrical losses through two
motor/generators are about 20%.

As you say the parallel approach also avoids the need to size the
electrical equipment large enough for the full load - the generator is
only 30KW even though the engine can output close to 60kW.  The motor
driving the wheels is 50kW as an additional 20KW can come from the
battery.

kevin

Re: Who Killed the Electric Car?
On Sat, 17 May 2008 18:58:49 -0700 (PDT), kevin93

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That is way past remarkably crappy motor and generator efficiencies.
Both are typically each 95 to 98 percent efficient.  Hell the antique
"Molly Long Legs" topped 99%.

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Re: Who Killed the Electric Car?
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I don't know about those you mention but the published peak efficiency
of the ones in the Prius (including the inverter) are about 93%, put
two in series and the losses to convert from mechanical energy back to
mechanical energy when operating at peak efficiency would be about 15%
- for other operating conditions they can be a lot worse, hence my 20%
number.

AC Propulsion (www.acpropulsion.com) only claim 91% from battery to
shaft for their system with 86% with a "road load" (implying an
average under normal usage).  That is even lower than the Toyota
figure.

When considering regenerative efficiency the numbers get even worse -
the battery may only have a 70% efficiency giving only a 50% overall
energy recovery efficiency.

Undoubtedly the efficiency could be improved but would add weight and
cost - Toyota and Honda are the only manufacturers with real-world
experience of producing this class of machines in million unit
quantities so presumably these designs represent their view of the
optimum compromise for this application

kevin

Re: Who Killed the Electric Car?
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AC motors are not all that hard to generate power with, if you already
have AC power systems to run them.  If the slip frequency goes
negative, the terminal impedance of an AC motor has a negative real
component.

Re: Who Killed the Electric Car?
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They are permanent magnet AC synchronous 3-phase motors - so they
don't need excitation.

They use a DC rail of up to 500V (650V in other Toyota models) feeding
three half bridges to drive the motor pretty much as you describe.

They are not set into reverse to regenerate though, the PWM duty-cycle
is controlled to give boost so that current flows into the battery
rather than out.  They can regenerate with a road-speed as low as
7mph, while allowing over 100mph before they run out of control
because the BEMF exceeds the rail voltage.

kevin


Re: Who Killed the Electric Car?
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                ^ ^ ^ ^ ^ ^ ^ ^

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Ok, then that's included in my list (maybe not explicitly).  Permanent
magnet you just strap on a rectifier and boost converter, but you have the
weight of the magnets to contend with, which I've got to imagine is quite
substantial in the many-HP range.  Or are these magnetized cage rotors, so,
er, semi-synchronous I suppose might be a way to put it.  (Full magnetized
rotor is synchronous, nonmagnetized "squirrel cage" rotor (which I was
thinking of with "AC (induction) motor") is the regular deal.)

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Alright, which is like what I went on to say, but AC?

God, that must be awful, you need to run a VFD in reverse.  So to suck
power from it, you need to synchronize the rate with the shaft?  Minus the
difference which is power drawn of course.

I suppose it's no BFD if you have a bidirectional (power in/out) self
contained VFD controller inside a feedback loop that's controlled by the
gas/brake pedals to make it feed power out of or into the battery, but
that's an awful lot of trouble.  I'd just as soon go for a frickin DC
motor, but maybe it's not as efficient.

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms



Re: Who Killed the Electric Car?
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Which isn't all that impressive by European or Japanese standards of
fuel efficiency. A BMW 3 series deisel saloon will manage that. eg

http://saveyourcash.co.uk/fuel/cardatadetail.aspx?mfr=BMW&model=3-Series-E90/E91/E92/E93&id63%2

Urban 39.8 Motorway 64.2 mpg to save you following the link.

(and it will turn in that sort of excellent fuel efficiency at speeds
well above the UK national speed limit of 70mph)

Factor in the energy costs of making and disposal of the Prius batteries
and the deisel BMW almost certainly wins on lifetime costs.

BTW: How long do Prius batteries last?

Regards,
Martin Brown


Re: Who Killed the Electric Car?
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http://saveyourcash.co.uk/fuel/cardatadetail.aspx?mfr=BMW&model=3-Series-E90/E91/E92/E93&id63%2
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Sure, but so far most European Diesels weren't able to pass emissions in
California. And wasn't there that company in Germany that made soot
filters that turned out not to work and they knew it? Read something
like that in the papers.


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No idea. AFAIK they keep them between 50% and 80% charge to make them
last. So far none of the neighbors here has needed replacement and most
of them use the Prius for lengthy daily commutes, including a grade you
have to tackle to get up here.

--
Regards, Joerg

http://www.analogconsultants.com /

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Re: Who Killed the Electric Car?
On Mon, 19 May 2008 09:18:53 -0700, Joerg

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Yep.  Overcharging (or running a battery close to 100% charge) or
running the battery into total discharge, kills NiMH batteries).
Toyota says at least 180,000 miles in tests, with some going to
250,000 miles.  180,000 is about 10-12 years.
<http://en.wikipedia.org/wiki/Toyota_Prius

--
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: Who Killed the Electric Car?



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http://saveyourcash.co.uk/fuel/cardatadetail.aspx?mfr=BMW&model=3-Series-E90/E91/E92/E93&id63%2
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Multiply by 0.8 to get US mpg.

Graham


Re: Who Killed the Electric Car?
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http://saveyourcash.co.uk/fuel/cardatadetail.aspx?mfr=BMW&model=3-Series-E90/E91/E92/E93&id63%2
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US fluid ounces are a bit bigger than Imperial, so the ratio isn't
1.25:1 as you might expect, but almost exactly 1.20:1.

Cheers,

Phil Hobbs

Re: Who Killed the Electric Car?



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http://saveyourcash.co.uk/fuel/cardatadetail.aspx?mfr=BMW&model=3-Series-E90/E91/E92/E93&id63%2
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So a US fl oz doesn't weigh an ounce ?

Graham


Re: Who Killed the Electric Car?
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http://saveyourcash.co.uk/fuel/cardatadetail.aspx?mfr=BMW&model=3-Series-E90/E91/E92/E93&id63%2
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No, a US gallon of water is 3.785 litres, which at 2.2046 pounds per kg,
comes out to 8.345 pounds.  An Imperial gallon of water is exactly 10
pounds, so the ratio is 10:8.345 or 1.198:1, just about 6:5.

Cheers,

Phil Hobbs

Re: Who Killed the Electric Car?
On Thu, 22 May 2008 19:19:23 +0100, Eeyore

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http://saveyourcash.co.uk/fuel/cardatadetail.aspx?mfr=BMW&model=3-Series-E90/E91/E92/E93&id63%2
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---
http://en.wikipedia.org/wiki/Fluid_ounce

JF

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