Electric Exige?? (Dale Vince - Wind Car)

[doug]

If using dual DC motors, I think the dual belts is an easy way to go...

That's exactly what I mean by, "dual rear motor setup with an independent belt drive to each wheel." Two motors, two belts, two drive wheels. Sorry if I wasn't clear enough. By "function of a differential when the car makes a turn," I mean that the outer rear wheel needs to spin faster than the inner rear wheel. You need to control for that since you don't have a mechanical system to do that for you. You actually have to tell that outer wheel how much faster to spin.

If not monitoring the individual wheel speed, I suppose you could look at the electrical load on each motor. You could then use feedback to balance the load between the two motors... that's essentially what an open differential does anyway. Not certain if that's the right algorithm in this case, though. If you're smart about it, you could make an effective LSD. At any rate, once you solve that control problem, seems you have half a TC system.

 

[TEG]

I think I got your point and you may have missed mine.

Or my point may be wrong.

In any case, I think with Tesla's AC motor they are controlling _exactly_ how quickly the motor spins. They have to create A/C waveforms precisely matched to motor RPMs. With a DC motor it is more of just "give it current and let it spin as fast it wants to". So with dual DCs if you round a corner and one wheel wants to spin at a different rate (since it is trascribing a different arc) then it is OK as one motor speeds up a bit and the other slows down. I don't think (but I could be wrong) that they need any special "simulated differential" electronics to do that. Now the effect may be something akin to "open differential" where you run into traction issues if one wheel is on a slippery surface. That is possibly one reason why the home brew person looking for shortcuts would use a simple dual DC motor setup, and a more sophisticated operation would use a single AC motor with a differential and torque limiting traction control.

It is a lot easier to design an EV that works OK in good conditions, but when you want something that is "user friendly" in all conditions (including on snow and ice) you have to do a lot more work.

 

[doug]

Yeah, ya know I read right past the DC distinction you were making since it seemed you missed I was already talking about dual belts.
I don't know what kind of motors they're using in the "wind car." I assumed they were brushless DC motors, which can allow for fine speed control. I just assumed each motor has it's own controller. (This is what I'd prefer they'd talk about rather than body work.)

Yeah, I guess if you used two standard DC motors wired in parallel from the same supply, the reduced load on the outer wheel would cause it to spin faster, making a kind of simulated open differential.




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[doug]

Yeah, I guess if you used two standard DC motors wired in parallel...

It occurred to me that I should have said wired in series.





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[dpeilow]

Looks like our friend Mr Vince is a few pennies out of pocket this morning...

BBC NEWS | England | Lincolnshire | UFO claim over wind farm damage

UFO turbine mystery: the theories in full

 

[doug]

Looks like our friend Mr Vince is a few pennies out of pocket this morning...

Ahh British idioms... Is that like few pence short of a shilling?
I can't tell if you're saying he lost some money, or if he's nuts, or both.

.

 

[dpeilow]

I can't tell if you're saying he lost some money, or if he's nuts, or both.

Just the former. I'm sure he's completely sound of mind...

 

[doug]

Danny of Danny's Contentment talking with Dale Vince. I guess this was recorded before the Lotus EV announcement.

http://www.dannyscontentment.net/2009/01/talking-to-dale-vince-from-ecotricity-about-the-wind-car/

 

[malcolm]

"99% of all UK road journeys are under 100 miles"

I think the figure for the US was 200 miles.

 

[TEG]

"I think swappable batteries are not a good idea myself"

Tesla & PBP seem to be pursuing that idea, but there are still plenty who question if it is ultimately the right answer.

By the way, that was a good interview, but I have trouble getting past the idea that Tesla has already "stole" much of Vince's thunder. His viewpoints would have seemed more fresh a few years ago.

 

[doug]

By the way, that was a good interview, but I have trouble getting past the idea that Tesla has already "stole" much of Vince's thunder. His viewpoints would have seemed more fresh a few years ago.

Yeah, you're totally right. I'm not sure I much see the point of his exercise. But I have no problem with him doing it. I just wish they gave more technical details that I would find interesting. What I'm struck by in the video is that, given what he is doing, he doesn't seem that knowledgeable about what's going on in the world of EVs.

He makes a point of taking a few jabs at Tesla. He mentions that a Tesla PR guy (it was Darryl) left a note on his blog that he should just buy a Roadster. Dale said he wanted a test drive, but that the PR guy never responded. This is at least the third time I've seen him relate that story (in print or in a video). Perhaps someone from Tesla should follow up with him.

He says that the Wind Car will have better handling than the Exige. I find that hard to imagine.

 

[TEG]

He also said he was talking to Lotus about the electric Elise idea but then Tesla came along. More sour grapes perhaps... I guess he has been working on this idea for a while, and then Tesla jumped in and ran with it more quickly than he was.

Anyways, the guy seems to have done quite well by himself selling wind generators as a good business, and I hope he has fun with his car project, regardless of what anyone else is doing.

 

[dpeilow]

Just by way of closing out this story:

UFO ruled out of wind farm prang ? The Register

Dale Vince, co-founder of site operator Ecotricity, elaborated: "The bolt failure was the effect not the cause of the problem. They have ruled out bolt fatigue and design problems, and we know that they were properly put on."

This will come as a terrible blow to ufologists, who were pretty well convinced ET was to blame or, failing that, a superultrasecret stealth drone project. Vince said: "To be honest I'm not surprised. But there was part of me that did hope it was a UFO as it was a lovely story.

"My favourite theory was that some alien race was trying to steal our turbine technology. They crossed galaxies to get here and when they arrive all they want is our wind technology. Wind power may be the holy grail of energy on Earth but not for stellar space travel."

 

[doug]

Just by way of closing out this story:

UFO ruled out of wind farm prang ? The Register

It wasn’t ET ‘wat done it’ | Energy | Zerocarbonista

We’ve just had the interim report from ENERCON, the manufacturer of our wind turbines, and they say that they found ‘classic signs of fatigue failure’ in the ring of about 30 bolts, that usually hold the blades on.

Interestingly though they’ve ruled out material or other defect in the bolts themselves, judging that the bolt fatigue is more likely ‘effect’ than ’cause’ of the blade loss.

So it fell apart on it's own. That's a tad concerning. Good thing no one was around.

 

[doug]

New wind car episode:

The Wind Car (5 of 6) | Transport | Zerocarbonista

The gist of this installment is basically that they have a lot more to do, actually had to redo some stuff, and are maybe just now at the half way point. It's disappointing in that is doesn't show any progress or at even talk about anything interesting. Just several shots of a CNC machining some aluminum. Again I'd prefer they talked more about the drivetrain.

 

[dpeilow]

The Wind Car ? Episode 6 of 6 | Transport | Zerocarbonista

 

[doug]

The Wind Car ? Episode 6 of 6 | Transport | Zerocarbonista

From the site:

The first thing I should say here is that this isn’t the last episode of our little video series – it can’t be - we just haven’t finished yet. So expect Episodes 7 and probably 8 of 6 before long…

That was clear from part 4, when he first said it would be 6 parts.

Second thing to say is I’ve got a new idea for a name. I’m quite taken with it.

The Mojo.

I actually think this is a good name for a product from an eccentric Brit.

Oh behave....



The video this time actually has a little more substance. There finally are some reasonable shots of a few drivetrain components. Unfortunately they don't bother to discuss them. Instead, most of the video is spent talking about hydrogen fuel cells, responding to that controversial Top Gear episode.

 

[doug]

Back in the Part 1 video, at one point there was a CAD drawing on a computer screen in the background that led me to believe they are using a belt drive. I've since been unable to find that shot (I think it's now intentionally blurred out). Anyway, this latest video shows the belts. We also see that they're using UQM brushless motors.

One detail on Dale's blog:

It seems that the motors arrived quite a bit bigger than the manufacturers spec and we’re having to adjust the transmission to fit them in (that’s a euphemism BTW… ). That’s been the main hold up anyhow.

I think that likely means they have to make a few design changes and remachine the transmission.

 

[doug]

Some shots of the chassis and battery compartment:

 

[dpeilow]

I suppose you could say that one big battery box is much like any other, but that does look quite ESS-like...