Motor contoller for an electric car
moo
Posts: 5
·I want to use a stamp 2 for a motor controller for an electric car. I am talking about a 120v system. Any ideas out there? I am new ready to learn!MOO!!!!
Comments
Messing with 120V is asking for trouble.
What kind of loads are we talking about?
(Engine size, speeds, whatever)
What fits the electric 'car' for a 3year old is probably not the best solution for a golf-cart, and certainly not for a full-fledged 50MPH car.
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Don't visit my new website...
I had a girl friend whose father had one.
For the 20th century, the batterys and recharge cycle made them never feasible. Cars were just too heavy and the recharge downtime was too much.
Are you planning to use fuel cells?
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
I am not trying to insult you, but you have a fundamental misunderstanding about electricity. Voltage is a measure of potential energy, ie the "desire" for electrons to conduct. Current is a measure of kinetic energy, ie the actual flow of electrons. They are related, and when you take the product of the two you get the Power of a system, measured in Watts. The measure of Power over Time is the total energy of the system and is measured in Joules (and sometimes Watt or Killowatt Hours). Every battery has a finite amount of energy stored within it, and once that energy is expended the cell is dead.
When placing batteries in series, as what will be needed to obtain your desired 120V, you are stacking the batteries energy into the potential energy side of the equation, this is good for getting a reluctant load to do work, but you do not increase the amount of time it will do the work. If you instead place the batteries in parallel, you keep the same voltage, but you are stacking extra energy into to kinetic part of the equation (current). This will extend the amount of time a load will do work. You cannot substitute one for the other, you need both voltage and current, the first for speed, the second for longevity.
Scientists have devoted thier entire lives to creating viable electric cars, and have been working on the problem for longer than the internal combustion engine has been in existance. There is a very good reason you don't see electric cars on the road everywhere you go, thats because trying to get a electric car to have the speed and longevity of a ordinary car you need a massive amount of batteries. And with each battery you add, you increase the weight of the vehicle, thereby increasing the work that needs to be done, in which you have to add more batteries, which increases the weight of the vehicle.....
This is just like space rockets, to get a single 2 ton sattelite in orbit, you need so much fuel, but that fuel and the containers and rocket engines add weight, so you have to use more fuel and rockets, and more fuel and rockets, until you end up with a rocket that is several thousand times more heavy than the satellite.
Im not trying to completely discourage you for attempting this, Im just trying to get you to understand how enormous of a task you are undertaking. Most scientists that work in this field have come to the conclusion that there is no battery chemistry in existance yet that is efficient and reliable enough to make an economically viable electric car, thats why there is a huge push towards fuel cells, because they act like a battery, but chemically they follow more along the lines of a slow burning internal combustion engine.
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·1+1=10
Post Edited (Paul Baker) : 3/28/2006 4:31:10 PM GMT
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This is the most important information on this thread.
To moderator, this quoted text has been cut from original, and is the same as the text message
sent to me.......But it is not the correct text that should be quoted....
Bob N9LVU
Eventually I want to build a whole car from the ground up. I have nothing against internal combustion engines. I do have someting against all the extras put on cars that I may or may not want and usually can't repair. My car would have some batteries, an electric motor and a manual transmission. I would not have an exhaust system, an air bag (seat belts work fine for me and I wear them), oxygen and other emission related sensors. I also wouldn't have a plastic bumper that can't be repaired and cost 1,000 dollars to replace.
I am looking for simplicity and availability of spare parts. If I get a job in town (hopefully soon) I may even be able to get away with a 72v system. For a comuter vehicle, I consider electric the best way to go. I can already total up the cost of a new frame, transmission, batteries, conversion kit and all the needed accessories and it would be about half the cost of a rewgular new car. Of course I would be a glamorized dune buggy but I live in AZ and can live with that. I can add doors, windows, a tape deck and other accessories such as A/C later. Of course I could also take a car with a blown engine and convert it and save costs that way. Either way I save money and have a car I can live with and even better know how to and can fix.
Keep on dreamin'...... 40 miles, 75 MPH, air conditioned, uphill? never happen even if you spent $100,000!
Cheers,
Peter (pjv)
People do use them. In some cases they are registered and street legal. You can plug in a home and wait for the charge [noparse][[/noparse]no filling stations available]
But I have noticed one thing, people consitently run at night without lights. After all, when you are running low and want to get home, you have to make a choice - walk or no lights.
Good engineering and sucessful marketing is about recognizing what are real limits. In America, the manufacture would be legally libel for the driver that chooses to turn off his lights and run at night. It called the Law of Torts.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Excluding... heat??? AC??? Radio??? WIndows??? Seatbelts??? Carpeting??? Wipers??? Safty Glass?? Airbags??
Under the hood, lets see, the stuff that saves our earth (emission control)?? AutoMatic Xmission??? Power Breaks??? Power Stearing???
The cooling system??? On the outside there's the fiberglass??, bumpers???
The honest fact is it's going to cost you in excess of $12000 to buld the car, where as you can purchase a commuter car for under 8K.
And excluding the comfie seats and maybe some power options and the radio, most everything in a commuter car is needed, for safty of the operator or the car's operation. And being able to repair the stuff, well, thats what manuals are for. Living in Taiwan it may pump the cost up some, but the facts still remain.
Please, I'm not knocking you or the project: Todays technology for this type or project isn't for the happy home owner or small business, it's more like corprate development. It's a nobal idea, and a great project, but to use electricty to directly move 3200 lbs (average weight of a hybred car) at speeds up to 75 mph for 40 miles is just not cost effective. Now, if you were to limit your design specs to 55 Mph, include a high preformance alternate fuel combustion motor with the electric battery system, you might achieve most of your design goals. Cars like these are retailed in the 28K range, that's post USA's EPA Grants and give backs.
Now that I've said all the negs, I'll restate this: I'm not knocking you or the project, as a matter of fact, I personally thing it's a great project.
TO add some things: The most effective electric vehicles are trains. They take a high powered Diesel motor that drives very effective generators that drive the motors. Maybe something along that lines might be something to look at.
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Just tossing my two bits worth into the bit bucket
KK
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Oh yeah, youll likely have to forgo the idea of an A/C, they are too power hungry. You may be able to design a passive cooling system using a air exchanger and a water resivior you would fill with chilled water when ever you wanted a cooler cabin, but youd have to bleed the system and refill it frequently.
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·1+1=10
Post Edited (Paul Baker) : 3/29/2006 3:51:32 PM GMT
Anyway, you will want to go with 4 smaller motors(one for each wheel) instead of one big one.
They won't weigh more than the big one, and they can be placed out by the wheels themselves, allowing you to get rid of a heavy driveshaft. (They also tend to be much cheaper)
You need to pick motors that can be used as generators as you can then use them for 'induction braking' and reclaim some energy when you slow down. (Or on long downhills... )
forget a decent stereo(maybe a radio, but that's it), and an AC is absolutely out of the question.
What are the regulations regarding lights in AZ?
(Here in Norway we have to use 'dimmed' headlights all day, which adds up to about 80W)
Rebuilding an older car is also a bad idea.
Even if the trunk and tank area is built solidly enough to carry the batteries, the front is built much too solidly(ready: heavy) to hold an engine.
And that doesn't account for all the other bits you don't need and also adds weight to it
I'd suggest tubular or box-section steel and Aluminium and with fibreglass body on top of that.
Maybe even an open-top model(as you won't be having an AC)
Use thin, soft plastic(like that used in windows in large tents or boats) for side and rear-windows.(In conjunction with a softtop, of course)
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Don't visit my new website...
There are quite a few homebuilders churning out EVs. Just because a product doesn't suit the mass market, doesn't make it worthless. People will forgive their homebuilt projects things that they'd never forgive from a mainstream manufacturer. Human nature, I guess [noparse]:)[/noparse]
There's a lot more of it in the UK than Norway, though - we've got a thriving homebuilt / kitbuilt car community & industry already, although that's normally aimed at performance rather than green-ness. (Sure, one of my cars has an engine less than 1 liter - but it's also got 180bhp and weighs 550Kg - meets all the low tax requirements, but is plenty of fun. No roof or impact protection to speak of [noparse]:)[/noparse]
As far as I can tell, our original poster wasn't planning to build the motors, the controllers or the charger himself - those things are all available off the shelf. _controlling_ them from a stamp, and using it to do things like range prediction, battery level monitoring, and a lot of the other frippery makes some sense.
Lithium Ion batteries are becoming (more) affordable, at long last. http://groups.yahoo.com/group/ThunderSky/ has a community of users.
Steve
http://dictionary.reference.com/search?q=frippery
Steve
I think you have a noble cause, but I expect you need to do some more homework. Your expectations may just be a touch beyond reasonableness. When you say "car" I presume you mean like an ordinary vehicle with all the necessities; heat, lights, etc., and not just some battery powered "skateboard".
Current car manufacturers make hybrid vehicles because battery-only technology is yet too limiting to be practical. If you are wishing to make this yourself for the "$20,000 easy" as per your PM to me, then I suggest some quick calculations to assess the reasonableness, and I'm going to make some assumptions.
You suggest 120 volts. Current manufacturers use about 300 to 350 volts made up of a stack of "D" sized NiMHi cells, because the currents required at 120 volts are just too awkward to deal with........ but you may have better technologies than Toyota or Ford, who knows. Their batteries are intended to "assist" in acceleration, and last for only a few minutes.
Let's do some calculations based on the desire to run at highway speeds for say an hour.
So we would need about 50 HorsePower for an hour; at 100 % efficiency, thats equivalent to about 37,500 watt-hours. At 120 volts, that's about 300 Amps. At such draw rates battery efficiencies get really crappy, so a "regular" car battery can probably deliver about 20 amp-hours, so at 12 volts let's say 250 watt-hours. That implies 150 batteries.
The weight will be around 50 pounds each, so that means about 7,500 pounds........ oops it will take another 10 HorsePower to deal with that, so add another 30 batteries and 1,500 pounds.
What, you want to drive in the winter and need heat?........ then that sounds like about 10,000 (coolish) to 20,000 (toasty) BTU/Hr, so another 5,000 Watt-Hours......... oops, another 20 batteries and 1,000 pounds. Getting kinda heavy...... 10,000 pounds for batteries alone!
So sizing this up, 150 + 30 + 20 batteries, let's see, thats 200 right? At 3/4 cubic foot each, thats about 150 cu ft, translating to 10 feet long, 5 ft wide by 3 ft high....... oops, where you gonna sit?
As to cost, using a price of $30 each (quantity purchase) that's about $6,000...... not bad for an hour's highway outing.
Now you need to recharge these overnight?......... Let's see, considering the dischare inefficiencies we will probably need to pump 100,000 watt-hours back in. Well, an efficient charger should take care of that in about 10 hours at a rate of 10 Kilowatts........ oops, just blew the size of the main panel; better get a bigger one installed to deal with the extra 45 amp load (220V). Wonder what that will cost.
Again, a recharge cost of $10 (10c per KWH) for an hour's winter drive is not too bad! Hey, where are those 500% efficient solar panels when you really need them?
What, those regular batteries used in a deep draw application only last for 200 charges ?........ oops, we'll need to change them out once per year. Oh well, the cost of "going green".
Wait, we'll get those batteries that are meant for purposes such as this........ oops they cost $625 each (actual quotation)..... gosh that's $125,000 ....a tad on the pricy side. But hey, they're more efficient in deep discharge applications, so maybe we'll only need 100 of them. There; $62,500 is quite affordable, and you won't have to sit as high to boot!
I too am interested in the concept of battery powered cars, but I think I'll let the big boys deal with it...... I suspect they're not as dumb as we might think!
On the other hand, you could be onto something the rest of the world is not yet aware of, and "your mileage may vary".
Cheers,
Peter (pjv)
All your calculations seem to be based on dragging a huge American-style car around. That's not really a sane way to do this. Look at it from the viewpoint of getting people from A to B, and it's much more feasible. Still not comparable to the good old internal combustion engine on cost & convenience, but that's because oil's cheating, long-term.
50bhp at highway speeds? That's a horribly inefficient car. Stage one - make it light, make it slippy, and get rid of as much extraneous tat as possible. This is all stuff that's been known for years. Decades, even.
Things like heaters - well, before the dawn'o'time, people used to wear clothes when it was cold. If you're on a tight energy budget , there are solutions other than heating the whole box up.
As for lights, there are plenty of technologies more efficient than incandescent lamps.
Your assumptions about batteries seem to be rather at odds with solutions used by EV manufacturers. Stacks of D-cells are a reasonable solution to a hybrid car, where you don't need to store much energy, but bulk lithium is definitely the winner at the moment.
EVs are interesting technology, and I don't believe they deserve the flat-out derision you seem to offer. You don't want to play? fine, but I don't think that your vitriol makes the world a better place.
(Hmm. Probably off-topic, even for the sandbox)
Steve
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I say go for it.· Do a little research into the voltage issues.··
Look at the Corbin Sparrow, a minimum car.· Its actually rated as a motorcyle.· It is a motor, three wheels, batteries, and a controller.· Goes 70MPH top speed.· Can go 60 miles on a charge.
http://images.google.com/images?svnum=10&hl=en&lr=&safe=off&rls=GGLD%2CGGLD%3A2005-13%2CGGLD%3Aen&q=corbin+sparrow
Maybe you could build something like it.
I'm glad you picked that up... I mean about my calculations being based on "dragging a huge American-style car around". That is EXACTLY what I stated when I began my post. With heat and lights and everything one would expect in a "normal" vehicle. And if you think that lugging around 10,000 pounds of batteries, or even half that, is lighter than a "huge American-style car", then I don't understand the gravity of the planet you are on!
One can't say someting will work by only analyzing a small portion (the stamp controller) of the problem; you need to consider the "whole enchelada".
Sure, by "relaxing" the normal expectations of what a "car" is, some sort of electric vehicle can be built. But it's performance would be sub-standard, and in fact I'm aware of at least some of those currently available are not permitted on state highways.
My purpose in making my post was to, more or less accurately, point out (with some humor) the considerations that need to be dealt with in such an undertaking, and simply stating "how do I control my electric car with a stamp" obscures the much bigger issue. There is no point in answering the first without considering the second.
My further purpose was as to cast serious doubt on MOO's PM to me where he stated that he "could do it for $20,000 easy". Clearly he has not given it much valid thought, and if he has, I believe he is grossly in error.
If he is that much more capable than Ford or Toyota then they should be very worried and he will become a wealthy person. But until that is demonstrated, my opinion is that idle unsubstanciated claims have no place in a forum such as this.
Cheers,
Peter (pjv)
For those of you who think I've been a little tough on Moo, I'd like to draw your attention to an interesting article. It is a description of battery weight vs vehicle weight and some calculations for the 40 plus horsepower required to slowly accelerate a small electric vehicle to highway speeds.
http://www.cloudelectric.com/generic106.html
Unfortunately the chap does not seem to realize that at high draw rates the "available energy" is a LOT less than at the "standard 20 hour" rates that he quotes. So the actual results will be much poorer than his calculations. On top of that, where I live, in a cold Canadian environment, battery capacity on a cold day is only 25% of the rated value.
Just a bunch of stuff to consider........
Cheers,
Peter (pjv)
I had a great uncle that was quite wealthy.
Family legend says that he was thrown out of college for wanting to build a flying maching a few years before the Wright Brothers.
He changed direction and built much of the electrical power system for the city of New Orleans.
Mo. Keep thinking and you will find a need that you can fill. Wanting to do something 'enviromentally friendly' is a worthy goal. Creating wealth is generally not enough, most of us want to be respected for making worthy contributions to our fellows.
You have just run into a set of limitiations that the real world places on electricity. It is cleaner, but generally more stationary. Of course, San Francisco does have electric buses and electric tolley cars; Taiwan, Europe, and Japan have electric railways. But these depend on staying on one pathway.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
(Plucked from the web, so check before trusting) -
http://www.energyadvocate.com/batts.htm
shows lithium batteries having 10 times the energy density of lead acid. Don't you think that might change the numbers a little?
Lead acid, DC motors, heavy cars - all are daft ways to build electric cars.
(Yes, Lithium cells will need heaters to kick-start them in cold weather, but, after that, you'll get their full discharge. No show-stopper)
Steve
Readers of this forum, while very open minded concerning electronics are a touch bigoted when their gas guzzling SUV are challenged.
You know, I worked with electric fork trucks for a couple of years, before the invention of power FETs. I’m still impressed.
When I was young (early 1960’s), the English manufacturer of electric milk floats (a small truck used to deliver milk – usually at night, always silently) explained the Seven’s rule to me. The optimum size of an electric truck carries 0.7 tons, traveling for seven hours at 7 mph. obviously, with the better batteries of today, a light car traveling 20 miles at an average of 30 MPH could carry two people.
Did you know that twin cam and VVT motors were first used on the 1908 Lancia but were regarded as a stupid idea right up until the early nineties.
Don’t discard an idea because it’s been done before.
Hey – there is something VERY special about driving an electric vehicle!
John Bond
·I am hoping that I can get to the the point in my knowledge curve that I can create a controller for them·with a basic stamp.· The tractors certainly do less than my recent basic stamp based robot prototypes do.· Of course, we are talking 36V motors controlled by 36V golf cart batteries.· Dont have the confidence to get into that with a boe bot board quite yet.
I say lets encourage the electric car.· Advances in conductive plastics, non silicone based solar cells (where the entire car body could be a plastics based solar cell) and better batteries, and the patroleum based car will be a thing of the past for short usage.· In the meantime, there a sure a lot of electric cars out there now, including the ones made just down the street from me.· http://www.myersmotors.com/.
We haven't been saying that creating electric vehicle cant be done, but such a vehicle capable of highway speeds, capable of long ranges, and mountainous terrain is really pushing the capability even given the advancements of the technology.
Tractors, golf carts, and milk dilivery trucks dont qualify in one or more of the criteria he established. The biggest drawback is that while many technologies have evolved by leaps and bounds, batteries for the most part have not (Lithiums while having much better charge density suffer from some very serious drawbacks of thier own, anyone remember the iPod debacle when Apple tried to insist that users would have to purchase a new iPod after the battery in their iPod refused to be charged after a year of use?)
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·1+1=10
Post Edited (Paul Baker) : 3/30/2006 4:01:27 PM GMT
What is the ratio for an equivalent volume Lithium battery under optimal conditons?
It isn't that it can't be done, but that it has been done and still remains cumbersome for freeroaming vehicles. Fuelcells are running Canadian Transit Buses and even generating power for whole office buildings. They seem to be possible eventual winner. Electricty is forever tied to wire and electrolic chemistry.
Also, when you drive over 50mph, the air begins to create significantly more resistance. That is why machines fly. Everyone knows that 50mph and under actually conservers fuel, even gasoline.
Popular Science and Popular Mechanics magazine revisited this topic many times over many years.
Why don't we all drive Stanley Steamers? Quite simply, the pressure relief valve would fog your glasses and take all the wrinkles out of your tuxedo on a trip downtown.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan