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  #11  
Old 07-24-2008, 01:33 AM
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Default Re: Newbie -- 3-phase AC, a place to start?

Here's a good link about a AC-conversion:

http://www.metricmind.com/ac_honda/main2.htm

I've been considering AC as well, but have decided to settle for DC in my first attempt for simplicity and cost reasons. I'm not intending tell you what to do or so, but it might be a good point to keep it simple the first time. You'll have enough speed bumps anyway so unless you're EXTREMELY stubborn and motivated or already have a lot of experience from similar projects odds are that it might be overwhelming to dig into an AC-project for your first attempt.

That said, if you decide to go for AC I hope you document it thoroughly. I'd love to read all about it.
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I like the Soliton's hi-tech build and ability to deliver whopping doses of current until someone screams "Uncle!"
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  #12  
Old 07-24-2008, 01:38 AM
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Default Re: Newbie -- 3-phase AC, a place to start?

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Originally Posted by Jacob Riskin View Post
Or in other words...no =P
In other words, we need to start an AC section on the wiki. This really would be helpful as AC can actually be cheaper than DC if you can make a controller work for a reasonable price. The Controller/Motor combos are super expensive though... depending on what you compare them to...
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Old 07-24-2008, 01:44 AM
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Default Re: Newbie -- 3-phase AC, a place to start?

Here's a thread about AC that was started just a couple of days ago.

http://www.diyelectriccar.com/forums...own-17319.html
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  #14  
Old 07-24-2008, 01:51 AM
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Default Re: Newbie -- 3-phase AC, a place to start?

this thread has a little bit of info too.

http://www.diyelectriccar.com/forums...ers-17084.html
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Old 07-24-2008, 11:07 AM
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Default Re: Newbie -- 3-phase AC, a place to start?

Hey guys.

Thanks for the links. The two threads on this forum I had already found, but since I'm a n00b I skipped over them.

I tinkered with electronics a couple years, but I never got anything to work really well when I picked up my own soldering iron. I got vacuum tubes to work well enough to make an audio amp, but it was substandard sound quality. Transistors never cooperated. They also smell nasty when you make'em pop.


I started a bookmark folder on my browser just for this. Or more specifically, one for AC and one for DC.

I may very well decide that a DC project is better for a first try. I want to make an educated decision on that though, which is why I'm asking.

I've been pondering alternate energy for a few years now, and over the last month or two I've come to the stark realization that transportation has to be electric. We may need a hybrid for long range until battery technology gets where we need it to be, but electric is the only way it can work in the long run. I also know that there are no electric cars available which are adequate to the task and cheap enough to afford.

I'm a builder, I love the building process. I have my own welder and a walking crane and a lot of other stuff, so the struggles I see in the other projects I've seen won't be the same ones I struggle with, at least not those parts. My struggle will be with the electronics.

I understand 3-phase in the abstract physics-book sense, and my most significant hero is Nikola Tesla (from the early days of 3-phase power, not so much the lightning bolts), but I don't understand semiconductors. I understand transformers but not how to figure the properties of the core.

If it gets to software, I'm a computer programmer so I don't think that would be much of a problem. I had thought for a first time project that I would use manufactured components, but if there is a well-mapped route to something I can build and somebody who will give or sell me the complete idiot-proof instructions to build it, I would try that too.
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Old 07-24-2008, 10:01 PM
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Default Re: Newbie -- 3-phase AC, a place to start?

Sorry, I know I'm beating a dead horse here, but here's another link

http://www.diyelectriccar.com/forums...ad.php?t=10402
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Old 07-28-2008, 02:50 PM
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Default Re: Newbie -- 3-phase AC, a place to start?

Hi all.

Just a few comments to see if I'm on the right track here. I'm recycling my first thread because I'm still a grass-green newbie.

First, it seems that the two main obstacles to AC cars are:
  1. Price
  2. Lack of availability of components, mainly motors and speed controllers.

I've also seen a user or two on multiple forums suggest that, if I can make my own speed controller, then AC could possibly be less expensive than DC. I would like some validation of that.

Doing my own searching on AC parts, it seems that all the companies which are working on production-ready cars in AC are building their own electronics. It also seems that there are almost no suitable motors specifically built for cars, and the ones which are out there are stupendously expensive.

In searching on AC motors, I see all sorts of speed controllers for 3-phase motors, but I don't see any implication that these motors are good for high RPM or high frequency AC. Is this true, or is there an unspoken assumption about the frequencies these motors can handle?

Regarding learning about this stuff, I wonder if it would be appropriate to get an RC model scale motor and controller and mess around with that. In other words, would it be appropriate to get a motor kit from http://www.gobrushless.com/shop/ and try to make a controller for that, and then work up from there?

For that matter, would it be feasible to use a controller for a smaller motor and make an amplifier stage, or does the controller need to have a slower timing for larger motors? Does a large motor controller just supply voltage and monitor current, or does it try to force the current by upping the voltage? Does the mass of the rotor make a difference to the software? The capacitance/inductance?

From the abstract educational sense, I am extremely attracted to getting an embedded controller and writing my own software. In the realistic garage mechanic sense, this scares me badly because I'll spend much more time doing that than converting the whole car.


Thank you for your time.
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  #18  
Old 07-28-2008, 02:58 PM
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Default Re: Newbie -- 3-phase AC, a place to start?

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Originally Posted by 1clue View Post
I've also seen a user or two on multiple forums suggest that, if I can make my own speed controller, then AC could possibly be less expensive than DC. I would like some validation of that.
It can very possibly be true (depending on what you can get an AC-motor for), but it'll be even cheaper (and a lot easier) to build your own DC-controller.
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I like the Soliton's hi-tech build and ability to deliver whopping doses of current until someone screams "Uncle!"
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  #19  
Old 07-28-2008, 06:25 PM
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Default Re: Newbie -- 3-phase AC, a place to start?

It may sound silly, but what about using a big honk'in truck alternator to do the "regen" thing?

One would have to "gear" it (or use pulleys etc.) in such a way as to apply enough torque load with the alternator to actually slow the vehicle significantly. Also there is the problem of how to "charge" something fast enough to provide a significant load for the alternator. Might make sense to use a super-cap as a temporary repository of the juice generated by the alternator. Then have some on-board charging circuitry to slowly feed that energy back to the main battery bank.

Yeah, I know, a lot of additional weight and volume and complexity.

It would work though!

jp
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