EV Digest 5924
Topics covered in this issue include:
1) Re: Switch protection
by Storm Connors <[EMAIL PROTECTED]>
2) Re: AC vs DC?
by Jack Murray <[EMAIL PROTECTED]>
3) Re: China Knock-offs (Re: "Strange EV on eBay" round 2)
by Lock Hughes <[EMAIL PROTECTED]>
4) Cheap ownership of Tesla Roadster - part-time (Craigslist)
by Cor van de Water <[EMAIL PROTECTED]>
5) Re: AC vs DC?
by [EMAIL PROTECTED]
6) Re: Cheap ownership of Tesla Roadster - part-time (Craigslist)
by Jack Murray <[EMAIL PROTECTED]>
7) RE: AC vs DC?
by "Michael Trefry" <[EMAIL PROTECTED]>
8) RE: China Knock-offs (Re: "Strange EV on eBay" round 2)
by Cor van de Water <[EMAIL PROTECTED]>
9) RE: AC vs DC?
by "Michael Trefry" <[EMAIL PROTECTED]>
10) RE: AC vs DC?
by Cor van de Water <[EMAIL PROTECTED]>
11) RE: Join In! WAS : AC vs DC?
by "Michael Trefry" <[EMAIL PROTECTED]>
12) Re: AC vs DC?
by Lee Hart <[EMAIL PROTECTED]>
13) Re: AC vs DC?
by Lee Hart <[EMAIL PROTECTED]>
14) Re: AC vs DC?
by "Mike Kaplan" <[EMAIL PROTECTED]>
15) Re: AC vs DC?
by "Mike Kaplan" <[EMAIL PROTECTED]>
16) Re: AC vs DC?
by "Death to All Spammers" <[EMAIL PROTECTED]>
17) Re: AC vs DC?
by Lee Hart <[EMAIL PROTECTED]>
18) Re: AC vs DC?
by "Death to All Spammers" <[EMAIL PROTECTED]>
19) Re: AC vs DC?
by "Mike Kaplan" <[EMAIL PROTECTED]>
20) Re: Switch protection
by Lee Hart <[EMAIL PROTECTED]>
21) Ecycle Motors
by "Mike Kaplan" <[EMAIL PROTECTED]>
--- Begin Message ---
The discussion was about contactors. I don't expect
that there is any protection being applied to the high
voltage side except what is provided by the
controller. Apparently the low voltage side is viewed
as a problem to be solved. If so, all the other relays
would seem to need addressing. Since I am about to
wire this thing up, I'm interested.
Thanks,
storm
--- Lee Hart <[EMAIL PROTECTED]> wrote:
> Storm Connors wrote:
> > I can recall using capacitors across switches to
> limit
> > arcing on disconnect. Now I am seeing several
> posts
> > that suggest using diodes and even zener diodes
> across
> > switches to remove back emf surges on opening (and
> > closing?) switches. Where can I get info on this?
> I am
> > wondering how to determine what switches need the
> > protection and how to determine the values for the
> > components used.
>
> There is a long and rich history of arc suppression
> techniques on
> switches (and by extension, it applies to
> transistors as well). The
> exact circuit and components used depends on the
> type of load.
> Fundamentally, the arc suppression network's job is
> to shape the voltage
> and current waveform to give the switch time to
> complete its transition
> between "off" and "on".
>
> Every type of load requires a different network.
> What load are you
> switching, and what kind of switching device are you
> using?
> --
> Ring the bells that still can ring
> Forget the perfect offering
> There is a crack in everything
> That's how the light gets in -- Leonard Cohen
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377,
> leeahart_at_earthlink.net
>
>
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
What about the drag of the brushes on DC motors, isn't that significant?
It is quite significant for R/C sized motors.
Jack
James Massey wrote:
At 04:39 PM 26/09/06 -0400, Don wrote:
I have heard there is a safety factory in the AC vs DC. If the
controller
fails on a DC you have a full power situation? If this happens in AC
it just
shuts down?
A properly designed DC controller like a Zilla, is supposed to shut down
on fault. Curtis controllers and their kin can short their power stage
and it is up to the operator to drop off the contactors to remove power.
AC systems if they fully short a power stage and put DC on the rotor
attempts to lock the rotor, but only 1 of the 6 transistors in the
bridge shorting will (if designed right) cause the drive to shut down
safely. Both AC and DC could develop a system fault that results in the
controller "thinking" you have just floored the accelerator, and
responding to that.
But, that said AC systems are "safer" if you are buying the 10-year
warranty on a Siemens, as the reliability is (should be) there. A Curtis
is "not so safe" as you need to add your own safety systems. A Zilla has
many of the safety attributes of an AC system, but the risk of runaway
is higher with a Zilla than with a siemens AC system, as a Zilla system
is spect by hobbyists, where a Siemens system is a package designed by
engineering teams.
To get a Zilla to runaway would require the power stage to fault AND the
traction contactor/s to weld shut. Since the Zilla tests the B+ traction
contactor each power-up and self tests itself a lot, it is an unlikely
scenario.
AC motors are lighter and able handle about double the RPM of a DC motor.
For a given power rating AC motors are generating half the torque and
rev twice as hard to develop the same horsepower.
Three phase AC motors take less starting amperage then a single
phase. They
are known to last longer than single phase AC I would assume they
would last
longer than DC as well because of this.
3-phase motors spread the load around 3 phases to draw less current, but
the same size/same load motors DOL started will draw a similar amount of
power. DC motors burn up for the same reason as AC motors - too much
amperage for too long. How long do DC motors last? I have a late 1950s
(as near as I can tell) motor that will be in my truck soon. I wouldn't
think of putting an AC motor of that age in a vehicle (but not due to
its age, due to design and engineering reasons)
Less starting amperage is also easier
on the batteries.
Less starting amperage is an irrelevant comment, since most AC systems
use high voltage, with lower battery Ah, (i.e. the current may be 3x
less, but the cells are 3x smaller so the stress is the same). For a
given horsepower being delivered, if a vehicle and battery pack are the
same mass, the stress on the cells will be equal
All manufacturers of full speed production vehicles used AC motors in the
last 10 years that I know of.
Because AC is "Sexy" technology, but I think you are wrong in that
Phillipe (IIRC) commented that some French manufactured cars (probably
by percentage of production EVs more than half of those made recently)
use sep-ex DC systems, from a manufacturer that produces reliable, safe.
proven controllers.
Hope this helps
Regards
[Technik] James
--- End Message ---
--- Begin Message ---
Would anyone buy a car from the Japanese? Not so long ago, the
Japanese cars were cute little novelties and fun for a chuckle?
Some listers will know of Deafscooter (Craig Uyeda):
http://www.austinev.org/evalbum/570.html
Craig has bought many of the "Boreem" brand "dolphin" style scooters
(straight outta Yong Kang CN) over the years, often upgrading. Craig
reported on how the quality of components improved noticeably with each
new year... (OK, yah, they're still butt-ugly <grin>)
I don't bet usually, but I'd feel pretty comfortable betting that
things will improve quickly w/the Chinese EVs. Some *smart* North
Americans will be egging them on, ready to buy NA-standards product by
the container loads
:)
tks
Lock
Toronto
Human/Electric Hybrid
--- bruce parmenter <[EMAIL PROTECTED]> wrote:
> Just as was POSTed this China company is making a Smart looking
> knock-off with a nEV performance:
>
http://www.ieb.cn/com/business9/cp_detail.php?id=1993&nowmenuid=23&cpath=0272:0275:0280:&catid=280
>
> If one did buy it, would the owner's local DMV register it?
> Could they drive it on U.S. streets?
> What is next? Knock-off EV parts/components for sale?
> www.evparts.cn ???
>
> Bruce {EVangel} Parmenter
>
> ' ____
> ~/__|o\__
> '@----- @'---(=
> . http://geocities.com/brucedp/
> . EV List Editor, RE & AFV newswires
> . (originator of the above ASCII art)
> ===== Undo Petroleum Everywhere
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
What if you really want to drive the Tesla Roadster
but don't have the money?
Get a time-share!
I must say - it is a compliment to the marketing of
Tesla to see how much traction they have created for
their product and EVs in general!
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
http://sfbay.craigslist.org/sfc/car/212597198.html
Looking for partners to buy a Tesla Roadster Electric Sports Car - $10000
(haight ashbury)
----------------------------------------------------------------------------
----
Reply to: [EMAIL PROTECTED]
Date: 2006-09-26, 1:12PM PDT
Hello,
I am setting up a partnership that will buy a Tesla Roadster electric sports
car. Check it out here:
http://www.teslamotors.com
I am looking for partners to join. The car is $100k, but for $10k plus
expenses (garage, insurance etc.), you will get a 10% share of the car, and
will be able to use it 10% of the time. If you are interested, please let me
know.
-jon
--- End Message ---
--- Begin Message ---
A higher speed motor advantage is you can get away with one gear ratio and
you do not need a multiple ratio transmission.
Are not DC motors single phase? I have seen large single phase AC motors and
the three phase motors of the same power that are much smaller. I would
assume they weigh less?
Even if they were the same size a DC motor still takes a lot more amperage
during start up than a three phase. I would think this would be harder on the
batteries. Every time you take off from a stop your putting this demand on
the batteries. Is this incorrect?
Don
In a message dated 9/26/2006 4:01:49 PM Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Ahh, the old FWC inverter fault issue. We're working on it. As for AC
motors being lighter, I cannot agree with that as the rotors are typically
much heavier while stators are fairly similar. I've never seen AC power
densities even close to that of the PM machines. And since when was higher
speed desirable? Higher rpm means higher gear reduction and even more
efficiency losses. If you can get the same output power at half the speed,
isn't that a better alternative?
I should probably mention that I work for a motor manufacturer. I am not
here to sell anything or to champion my own cause. I am here to stay
current on the state of EV systems and the issues that people are currently
encountering. All in all this is good discussion.
I have heard there is a safety factory in the AC vs DC. If the controller
fails on a DC you have a full power situation? If this happens in AC it
just
shuts down?
AC motors are lighter and able handle about double the RPM of a DC motor.
Three phase AC motors take less starting amperage then a single phase. They
are known to last longer than single phase AC I would assume they would last
longer than DC as well because of this. Less starting amperage is also
easier
on the batteries.
All manufacturers of full speed production vehicles used AC motors in the
last 10 years that I know of.
Don
--- End Message ---
--- Begin Message ---
what a joke..the first 100 are sold out anyway, smells like scammmmmmmm
Cor van de Water wrote:
What if you really want to drive the Tesla Roadster
but don't have the money?
Get a time-share!
I must say - it is a compliment to the marketing of
Tesla to see how much traction they have created for
their product and EVs in general!
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
http://sfbay.craigslist.org/sfc/car/212597198.html
Looking for partners to buy a Tesla Roadster Electric Sports Car - $10000
(haight ashbury)
----------------------------------------------------------------------------
----
Reply to: [EMAIL PROTECTED]
Date: 2006-09-26, 1:12PM PDT
Hello,
I am setting up a partnership that will buy a Tesla Roadster electric sports
car. Check it out here:
http://www.teslamotors.com
I am looking for partners to join. The car is $100k, but for $10k plus
expenses (garage, insurance etc.), you will get a 10% share of the car, and
will be able to use it 10% of the time. If you are interested, please let me
know.
-jon
--- End Message ---
--- Begin Message ---
I definitely like to fiddle. I have an 88 BMW I am constantly tweaking.
Mechanical cars are easy (at least old ones). I just feel a little out of my
realm with the electric stuff.
I can put together a computer from scraps, but then I don't have to know
jack about amps and ohms and volts and capacitors and transformers.
Ok, I have more reading to do.
Thanks!
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Lee Hart
Sent: Tuesday, September 26, 2006 1:20 PM
To: [email protected]
Subject: Re: AC vs DC?
Michael Trefry wrote:
> Is there a kind where I can engineer a stable reliable efficient car
> that I can drive around AND allow for tinkering with it?
Let's compare it to regular ICE cars. If you're the sort of person that
likes tinkering with cars, then an older car (1960's or earlier) is a good
choice. No computers or secret black boxes. You can take almost anything
apart, and put it back together again. If you have the manuals, it will even
work afterward! :-)
If you're the sort of person that just wants to buy a car and drive it, then
a newer car (1990's and newer) is a better choice. It's more reliable, works
better, and you can take it to the dealer for repairs.
But, you can't fix it yourself!
> I like the idea of regen. Can't you do that with a DC motor by adding
> on a generator?
Of course! The only reason regen is less common on DC systems is because
most builders buy based on minimum cost, and so pick motors and controllers
without regen. You can spend a little more and get regen. Or retrofit it to
a cheaper setup, by using a separate DC generator and controller.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Hi Lock,
The issue here is that this Chinese company made an
unauthorized (illegal) copy of the Mercedes Smart car
styling and are trying to sell it without providing any
proof that it can be driven on US highways or even that
the cars are actually available (the answer by the rep
indicated that they can be imported by the containerload)
and they ave deliberately mis-represented these cars by
putting "Smart City car" in the advertisement text, which
has since been modified.
Thay show the car on the street, suggesting that it can
be driven on public streets, and they use tactics like
photo-shopping to hide the fact that the photos are from
China and that the brand / type is different from Smart.
The buyers (if they receive a car at all) will likely have
to wait until their money order has financed the import
from China by container, after which they can enjoy
driving their $15,000 golf cart around on their own property
and maybe, if they are really lucky they can register it as
a NEV and drive around in the neighborhood with a range of
up to 25 miles or so, until a defect surfaces and they
have to deal with a vague Chinese company.
That is a far cry from the claims in the advertisement and
the image that the Smart Car has, which is a Freeway capable
vehicle, manufactured by a very reliable company (Mercedes).
As EV community, we should put some effort in exposing and
even stopping scams like this, enabling the victims to
be informed beforehand and pointing them to the infringements
so they can file their case if it is already too late.
I think this case actually allows both Mercedes to file for
infringement on their styling as well as any unhappy buyers
to file with the FBI for misleading representation of goods.
I am not a lawyer, though and if this would happen to me,
then I would certainly like to know in advance if anyone
has more info on the background of the seller and the
company which is not obvious from the ad.
But - as so often quoted:
"If it is too good to be true, it usually is."
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Lock Hughes
Sent: Tuesday, September 26, 2006 4:06 PM
To: [email protected]
Subject: Re: China Knock-offs (Re: "Strange EV on eBay" round 2)
Would anyone buy a car from the Japanese? Not so long ago, the
Japanese cars were cute little novelties and fun for a chuckle?
Some listers will know of Deafscooter (Craig Uyeda):
http://www.austinev.org/evalbum/570.html
Craig has bought many of the "Boreem" brand "dolphin" style scooters
(straight outta Yong Kang CN) over the years, often upgrading. Craig
reported on how the quality of components improved noticeably with each
new year... (OK, yah, they're still butt-ugly <grin>)
I don't bet usually, but I'd feel pretty comfortable betting that
things will improve quickly w/the Chinese EVs. Some *smart* North
Americans will be egging them on, ready to buy NA-standards product by
the container loads
:)
tks
Lock
Toronto
Human/Electric Hybrid
--- bruce parmenter <[EMAIL PROTECTED]> wrote:
> Just as was POSTed this China company is making a Smart looking
> knock-off with a nEV performance:
>
http://www.ieb.cn/com/business9/cp_detail.php?id=1993&nowmenuid=23&cpath=027
2:0275:0280:&catid=280
>
> If one did buy it, would the owner's local DMV register it?
> Could they drive it on U.S. streets?
> What is next? Knock-off EV parts/components for sale?
> www.evparts.cn ???
>
> Bruce {EVangel} Parmenter
>
> ' ____
> ~/__|o\__
> '@----- @'---(=
> . http://geocities.com/brucedp/
> . EV List Editor, RE & AFV newswires
> . (originator of the above ASCII art)
> ===== Undo Petroleum Everywhere
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
Please excuse my ignorance, I'm just trying to understand.
How can DC be the same thing as AC?
If I'm not mistaken, DC is direct current, meaning a steady stream of
electrons going in a single direction, while AC is alternating meaning that
it's constantly going back and forth. Right?
There is no +/- with AC right?
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Lee Hart
Sent: Tuesday, September 26, 2006 3:00 PM
To: [email protected]
Subject: Re: AC vs DC?
Andrew Roberts wrote:
> All excellent points, however, you forgot one category: Brushless DC.
> All the features of the AC systems, with better efficiency, torque,
> and power density. Prohibitively expensive at this time, I know, but
> that will change with demand.
"Brushless DC" is the same thing as "Synchronous AC".
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Yes, this is incorrect if you use a modern controller.
The switching controllers will "transform" the battery
voltage and current from high V, low Amp to low V, high Amp
when a motor is turning slow.
This is a beneficial effect of the PWM used in controllers,
the battery supplies the current only in a small fraction
of the time and with the motor (almost) stalled it will
react as an inductor, the current will continue to run
through the motor when it is short-circuited by the
controller (usually through a set of diodes that allow the
motor current to continue without supplying a voltage).
Only older (contactor) controllers do not have this benefit,
so the motor current equals the battery current and the
efficiency and life expectancy of batteries suffer.
Hope this clarifies,
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of [EMAIL PROTECTED]
Sent: Tuesday, September 26, 2006 4:18 PM
To: [email protected]
Subject: Re: AC vs DC?
A higher speed motor advantage is you can get away with one gear ratio and
you do not need a multiple ratio transmission.
Are not DC motors single phase? I have seen large single phase AC motors
and
the three phase motors of the same power that are much smaller. I would
assume they weigh less?
Even if they were the same size a DC motor still takes a lot more amperage
during start up than a three phase. I would think this would be harder on
the
batteries. Every time you take off from a stop your putting this demand on
the batteries. Is this incorrect?
Don
In a message dated 9/26/2006 4:01:49 PM Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Ahh, the old FWC inverter fault issue. We're working on it. As for AC
motors being lighter, I cannot agree with that as the rotors are typically
much heavier while stators are fairly similar. I've never seen AC power
densities even close to that of the PM machines. And since when was higher
speed desirable? Higher rpm means higher gear reduction and even more
efficiency losses. If you can get the same output power at half the speed,
isn't that a better alternative?
I should probably mention that I work for a motor manufacturer. I am not
here to sell anything or to champion my own cause. I am here to stay
current on the state of EV systems and the issues that people are currently
encountering. All in all this is good discussion.
I have heard there is a safety factory in the AC vs DC. If the controller
fails on a DC you have a full power situation? If this happens in AC it
just
shuts down?
AC motors are lighter and able handle about double the RPM of a DC motor.
Three phase AC motors take less starting amperage then a single phase. They
are known to last longer than single phase AC I would assume they would
last
longer than DC as well because of this. Less starting amperage is also
easier
on the batteries.
All manufacturers of full speed production vehicles used AC motors in the
last 10 years that I know of.
Don
--- End Message ---
--- Begin Message ---
I'm in CT.
I haven't seen much of an EV movement up here. Not much in the way of
alternative energy at all.
The only thing I've seen in this area is NG vehicles.
Mike
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Bob Rice
Sent: Tuesday, September 26, 2006 4:39 PM
To: [email protected]
Subject: Join In! WAS : AC vs DC?
----- Original Message -----
From: "Death to All Spammers" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, September 26, 2006 2:05 AM
Subject: Re: AC vs DC?
> > See I told you I know next to nothing.
> >
> > So these DC 9s are not 9v, but 9 What? Amps? Inches?
> > Hi EVerybody, especially you newbees;
Mike , you didn't say WHERE you are? If you are neer a EAA(Electric
Auto Assoc.) chapter, might be one right in YOUR 'hood! If so, check them
out on the Web, go over to a meeting, if you're lucky you will get to meet a
few cars, driven in by their loving owners. THEN you can go crazy with the
queations, and EVen get to take a spin in an EV for your First EV Grin!"EV
Grin" is part of our language here. You will get/ have it, especially if you
are in Portland OR and get a ride in John Wayland's White Zombie, race car
0-105MPH in the quarter. You WILL have an EV grin, especially when he blew
away a Corvette at the light!
All kidding aside, the List, we're here to help and have a fun time. Get
out to the EVents, say hello and join in in a fun society.
> My two watts worth
Bob
--- End Message ---
--- Begin Message ---
Andrew Roberts wrote:
Are there any brushless DC systems available today for hobbyist EVs that
don't cost $30k?
The Toyota and Honda hybrids all have brushless DC drives. You can buy
the whole car for under $30k. But, hacking their computers so you can
actually use it as an EV drive will be a challenge. :-)
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Peter Gabrielsson wrote:
It's true, there would have to be a divine miracle to make a inverter
based AC system run away.
It's not quite *that* unlikely! It takes a lazy design engineer, or a
software bug, computer crash, stuck accellerator pedal, etc. These tend
to be less likely in AC systems because they cost so much that more time
gets spent thinking about such errors, and putting in backup systems to
prevent them.
In contrast, most DC systems are designed for lowest cost. They've been
around for so long that design engineers get careless and make dumb
mistakes. Or, they get thrown together by hobbyists that don't think
about failure modes.
Done right, neither AC nor DC have problems with runaways. Done wrong,
they *both* do!
AC motors are lighter and able handle about double the RPM
of a DC motor.
This only depends on the design criteria when you built the motor. There
are DC motors that run well over 10,000 rpm; and AC motors that would
fly to pieces at even half that.
The maximum power-to-weight ratio of a motor occurs at max torque and
max rpm. It's about the same for both AC and DC motors, and is most
likely set by thermal issues (how LONG can you get that much power
before something melts).
As a rule, motor torque is limited by current, which is in turn limited
by wire size. The same limits apply for either AC or DC.
And motor rpm is limited by the mechanical strength of the rotor. For
high rpm, you don't use weaker aluminum windings (like cheap induction
motors) or long skinny copper commutator bars held only by glue (like
cheap DC motors).
Three phase AC motors take less starting amperage then a single phase.
They are known to last longer than single phase AC I would assume
they would last longer than DC as well because of this.
All DC motors are by nature polyphase (often a lot more than 3).
The starting current of a DC motor is determined by its field design.
Actually, the same is true for AC motors.
All manufacturers of full speed production vehicles used AC motors
in the last 10 years that I know of.
True. However, these folks are hardly experts on EV design. The vast
numbers of commercially successful EVs (fork lifts, buses, trains, etc.)
are DC.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Ecycle (www.ecycle.com and www.ecyclemarine.com) make a brushless DC motor
for OEMs to incorporate into their products. I purchased a discontinued
model and am waititng for transmission hardware (sprockets and belts) to
install it in my sailboat and evaluate it. I will post a report after that.
Ecycle doesn't sell to consumers. I am hoping to become a conduit for the
hobbyist market but I want to evaluate mine first.
Ecycle claims 95% efficiency and up to 12kw peak on the 48v model. The
motors can be "stacked" to create a motor with twice the torque.
Mike
----- Original Message -----
> From: "Don Cameron" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Tuesday, September 26, 2006 1:22 PM
> Subject: RE: AC vs DC?
>
>
> > As my note stated it was within the context of: "comparing the
currently
> > available hobbyists AC and DC systems"
> >
> > Are there any brushless DC systems available today for hobbyist EVs that
> > don't cost $30k?
> >
> > Don
> >
> >
> >
> > Don Cameron, Victoria, BC, Canada
> >
> > see the New Beetle EV project www.cameronsoftware.com/ev
> >
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> > Behalf Of Andrew Roberts
> > Sent: September 26, 2006 9:59 AM
> > To: [email protected]
> > Subject: RE: AC vs DC?
> >
> > All excellent points, however, you forgot one category: Brushless DC.
> All
> > the features of the AC systems, with better efficiency, torque, and
power
> > density. Prohibitively expensive at this time, I know, but that will
> change
> > with demand.
> >
> >
> > Since this does not seem like the typical AC vs DC debate, I thought I
> would
> > weigh in. One thing to note though: we are not really comparing
"purely"
> > AC to DC motors, but comparing the currently available hobbyists AC and
DC
> > systems. So here is my pro and con list based on what we can readily
> > purchase today:
> >
> > AC
> > - regen
> > - can use higher voltages - smaller wires, but more batteries and more
> > connections
> > - wider power band
> > - can hold on hills without causing brush burnout
> > - somewhat more expensive
> > - Siemens, MES and Solectria are all AC systems
> >
> >
> > DC
> > - most powerful available to hobbyists (current leader in drag racing
> cars)
> > - can get higher power systems cheaper
> > - entry level is inexpensive on a weight & power basis
> > - lower voltage means less batteries and connections, but bigger wires,
> > fuses, contactors and breakers
> > - huge torque off the get go
> > - Warp and ADC are DC motors
> > - ADC and Zilla are controllers
> >
> >
> > Then there is looking at manufacturers:
> >
> > Siemens AC motor/controllers
> > - OEM quality, water proof, well built, made for automotive applications
> > - liquid cooled
> > - programmable
> > - easy to set up
> >
> >
> > Zilla Controllers
> > - made for EVs
> > - programmable
> > - can drive dual motors for electronic transmission
> > - very powerful
> > - liquid cooled
> >
> > Warp/ADC Motors
> > - the "standard" dc motor
> > - air cooled
> > - fork list motor used successfully in many, many EVs
> >
> >
> > Hmm, well that should get a few replies!
> >
> > Don
> >
> >
> >
> >
> >
> >
> >
> >
> > Don Cameron, Victoria, BC, Canada
> >
> > see the New Beetle EV project www.cameronsoftware.com/ev
> >
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> > Behalf Of Michael Trefry
> > Sent: September 25, 2006 5:46 PM
> > To: [email protected]
> > Subject: AC vs DC?
> >
> > Thanks to those who took the time to welcome me, and those who emailed
me
> > personally.
> >
> > I'm still trying to figure out exactly how I'm going to build this,
> although
> > I think I'm sold on the 914 (I Love those cars!)
> >
> > I may still go for the kit offered at evparts or electroauto, but I want
> to
> > understand my options before I nail myself down to a specific
technology.
> >
> >
> > >From some of the reading I've been doing AC seems to be more efficient
> > >than
> > DC in an EV.
> >
> > Are there disadvantages to using an AC system? Is it more complex,
> > expensive? Are there other limitations?
> >
> > It looks like 6v fla batteries are pretty standard, but all this talk
I'm
> > seeing about batteries is making me curious about what the best
> > cost/performance battery solution is.
> >
> > Ideally I'd like to get at least 60 miles on a charge, be able to get up
> to
> > at least 85mph and have some decent acceleration. I think a 0-60 in 20
> > seconds car would drive me insane.
> >
> > Suggestions anyone?
> >
> >
> > Thanks,
> >
> > Mike (the new guy)
> >
> >
>
--- End Message ---
--- Begin Message ---
Ecycle (www.ecycle.com and www.ecyclemarine.com) make a brushless DC motor
for OEMs to incorporate into their products. I purchased a discontinued
model and am waititng for transmission hardware (sprockets and belts) to
install it in my sailboat and evaluate it. I will post a report after that.
Ecycle doesn't sell to consumers. I am hoping to become a conduit for the
hobbyist market but I want to evaluate mine first.
Ecycle claims 95% efficiency and up to 12kw peak on the 48v model. The
motors can be "stacked" to create a motor with twice the torque.
Mike
----- Original Message -----
From: "Don Cameron" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, September 26, 2006 1:22 PM
Subject: RE: AC vs DC?
> As my note stated it was within the context of: "comparing the currently
> available hobbyists AC and DC systems"
>
> Are there any brushless DC systems available today for hobbyist EVs that
> don't cost $30k?
>
> Don
>
>
>
> Don Cameron, Victoria, BC, Canada
>
> see the New Beetle EV project www.cameronsoftware.com/ev
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of Andrew Roberts
> Sent: September 26, 2006 9:59 AM
> To: [email protected]
> Subject: RE: AC vs DC?
>
> All excellent points, however, you forgot one category: Brushless DC.
All
> the features of the AC systems, with better efficiency, torque, and power
> density. Prohibitively expensive at this time, I know, but that will
change
> with demand.
>
>
> Since this does not seem like the typical AC vs DC debate, I thought I
would
> weigh in. One thing to note though: we are not really comparing "purely"
> AC to DC motors, but comparing the currently available hobbyists AC and DC
> systems. So here is my pro and con list based on what we can readily
> purchase today:
>
> AC
> - regen
> - can use higher voltages - smaller wires, but more batteries and more
> connections
> - wider power band
> - can hold on hills without causing brush burnout
> - somewhat more expensive
> - Siemens, MES and Solectria are all AC systems
>
>
> DC
> - most powerful available to hobbyists (current leader in drag racing
cars)
> - can get higher power systems cheaper
> - entry level is inexpensive on a weight & power basis
> - lower voltage means less batteries and connections, but bigger wires,
> fuses, contactors and breakers
> - huge torque off the get go
> - Warp and ADC are DC motors
> - ADC and Zilla are controllers
>
>
> Then there is looking at manufacturers:
>
> Siemens AC motor/controllers
> - OEM quality, water proof, well built, made for automotive applications
> - liquid cooled
> - programmable
> - easy to set up
>
>
> Zilla Controllers
> - made for EVs
> - programmable
> - can drive dual motors for electronic transmission
> - very powerful
> - liquid cooled
>
> Warp/ADC Motors
> - the "standard" dc motor
> - air cooled
> - fork list motor used successfully in many, many EVs
>
>
> Hmm, well that should get a few replies!
>
> Don
>
>
>
>
>
>
>
>
> Don Cameron, Victoria, BC, Canada
>
> see the New Beetle EV project www.cameronsoftware.com/ev
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of Michael Trefry
> Sent: September 25, 2006 5:46 PM
> To: [email protected]
> Subject: AC vs DC?
>
> Thanks to those who took the time to welcome me, and those who emailed me
> personally.
>
> I'm still trying to figure out exactly how I'm going to build this,
although
> I think I'm sold on the 914 (I Love those cars!)
>
> I may still go for the kit offered at evparts or electroauto, but I want
to
> understand my options before I nail myself down to a specific technology.
>
>
> >From some of the reading I've been doing AC seems to be more efficient
> >than
> DC in an EV.
>
> Are there disadvantages to using an AC system? Is it more complex,
> expensive? Are there other limitations?
>
> It looks like 6v fla batteries are pretty standard, but all this talk I'm
> seeing about batteries is making me curious about what the best
> cost/performance battery solution is.
>
> Ideally I'd like to get at least 60 miles on a charge, be able to get up
to
> at least 85mph and have some decent acceleration. I think a 0-60 in 20
> seconds car would drive me insane.
>
> Suggestions anyone?
>
>
> Thanks,
>
> Mike (the new guy)
>
>
--- End Message ---
--- Begin Message ---
> In contrast, most DC systems are designed for lowest cost. They've been
> around for so long that design engineers get careless and make dumb
> mistakes. Or, they get thrown together by hobbyists that don't think
> about failure modes.
>
So, how often has a production DC vehicle (tug, forklift, whatever,
doesn't have to be street-legal) had a runaway situation (i.e.
something like MTBF)?
--- End Message ---
--- Begin Message ---
[EMAIL PROTECTED] wrote:
A higher speed motor advantage is you can get away with one gear
ratio and you do not need a multiple ratio transmission.
No; this is not related to motor rpm. There are plenty of examples of
one-gear EVs with both AC and DC motors. The motors can have any maximum
rpm from 13,000+ (with a huge reduction ratio) to direct drive (motor
directly drives the wheel at a few hundred rpm).
In fact, virtually all purpose-built EVs are transmisionless (only one
speed). Properly done, electric motors have a wide enough torque-speed
range to cover the entire range without shifting gears.
Are not DC motors single phase?
No; they are polyphase.
The little toy DC motors that sell for under $1 are 3-phase. You'll see
they have 3 lobes on their armature, and 3 commutator bars. They are an
exact inside-out version of a standard 3-phase AC motor.
Larger DC motors always go to higher numbers of phases. It improves
performance and efficiency. The same is true for AC motors; bigger
motors almost always increase the number of phases and/or poles.
I have seen large single phase AC motors and the three phase motors of
the same power that are much smaller. I would assume they weigh less?
Correct.
Even if they were the same size a DC motor still takes a lot more
amperage during start up than a three phase.
Actually, the old series DC motor has exceptionally *low* starting
current for a given amount of torque.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
> Ecycle doesn't sell to consumers. I am hoping to become a conduit
for the
> hobbyist market but I want to evaluate mine first.
>
> Ecycle claims 95% efficiency and up to 12kw peak on the 48v model. The
> motors can be "stacked" to create a motor with twice the torque.
>
>
I wondered who they sold to - I remember when they first had a mock-up
e-cafe-racer on their site, dismantled it, replaced it with a hybrid
bike with their own diesel power plant (that never got made), now just
these motors that a few people *have* actually gotten even when they
don't get a controller, all in the time Eteks have come and gone.
Where do they sell these? How do they compare to a German-built
PMG-132 of similar output ($800-100)?
--- End Message ---
--- Begin Message ---
Based on a press release I saw, one customer makes UAVs. I guess the power
to weight ratio makes it a natural for that application.
----- Original Message -----
From: "Death to All Spammers" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, September 26, 2006 8:31 PM
Subject: Re: AC vs DC?
> > Ecycle doesn't sell to consumers. I am hoping to become a conduit
> for the
> > hobbyist market but I want to evaluate mine first.
> >
> > Ecycle claims 95% efficiency and up to 12kw peak on the 48v model. The
> > motors can be "stacked" to create a motor with twice the torque.
> >
> >
>
> I wondered who they sold to - I remember when they first had a mock-up
> e-cafe-racer on their site, dismantled it, replaced it with a hybrid
> bike with their own diesel power plant (that never got made), now just
> these motors that a few people *have* actually gotten even when they
> don't get a controller, all in the time Eteks have come and gone.
> Where do they sell these? How do they compare to a German-built
> PMG-132 of similar output ($800-100)?
>
>
>
>
--- End Message ---
--- Begin Message ---
Storm Connors wrote:
The discussion was about contactors. I don't expect
that there is any protection being applied to the high
voltage side except what is provided by the
controller. Apparently the low voltage side is viewed
as a problem to be solved. If so, all the other relays
would seem to need addressing. Since I am about to
wire this thing up, I'm interested.
Ok; let's assume your contactor's coil draws 1 amp at 12 volts DC.
If you are switching it with a snap-acting mechanical switch, then it
would work even with *nothing* across the contactor's coil. On turn-off,
the voltage will spike up to 50-100v, and the contactor will drop out
very quickly. As long as the switch can handle this much voltage, it
works fine.
If you are switching it with a cheaper lower-voltage switch, then I'd
put one of the following across the coil to limit the peak voltage to
roughly 24 volts (most cheaper switches can stand this). Best choice is
first; worst choice is last.
1. a P6KE27CA (+/-27v 600wpeak) bidirectional zener diode
2. a 1N4749 (24v 1-watt) zener diode, with a 1N4001 (50v 1amp) diode
in series
3. a 1uF 100v capacitor, and 10 ohm 1 watt resistor in series
4. a 1N4001 (50v 1amp) diode
If you are switching it with a solid-state switch (transistor etc.), and
you know the breakdown voltage of that switch, then pick the zener
voltage to be about half of the transistor's breakdown voltage.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
I plan to evaluate the motor I purchased, so keep in mind that the info I
have is based on the ecycle web site and other internet sources, not real
world use.
The basic motor weighs 15 lbs and comes in different voltage configurations.
The 24v model has these specs:
1800 RPM at 24v
Max Amps: 400
Max HP: 12
Max Torque: 36 ft lbs
Efficiency: 95%
Torque Constant: .12 NM/Amp equals .0885 ft-lbs/Amp
The motors are brushless and require no maintence. The commutator is a
circuit board that uses Hall-effect transducers to change the winding
current. The circuit board provides two wires that can be connected to a
simple SPST switch to provide forward/reverse rotation.
A major cause of DC motor failure is heat built up due to PWM current
fluctuations. The ecycle motor avoids the fluctuating PWM and resultant heat
even though the motor can be used with standard PWM controllers.
My motor has a shaft that is 19mm in diameter and has a 6mm key.
The newer models replace the wire windings with solid metal which reduces
weight and manufact costs. Another press release states they developed a
10lb motor producing over 10 HP.
I'll provide more info as I can.
Mike
>
>
> I wondered who they sold to - I remember when they first had a mock-up
> e-cafe-racer on their site, dismantled it, replaced it with a hybrid
> bike with their own diesel power plant (that never got made), now just
> these motors that a few people *have* actually gotten even when they
> don't get a controller, all in the time Eteks have come and gone.
> Where do they sell these? How do they compare to a German-built
> PMG-132 of similar output ($800-100)?
>
>
>
>
--- End Message ---
