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Newbie -- 3-phase AC, a place to start?

8K views 18 replies 8 participants last post by  JeffPritchard 
#1 ·
Hi all.

I've read through the WIKI main page and cycled through the links there, as well as searched for some key terms. Note that this is over about 2 days, so I can't say I've searched everything on the site. I thought maybe I could save some time though if there's a section I'm missing.

I've been moderately interested in alternate energy in general and electric vehicles in specific for some time now, and I just found this site a couple days ago. I'm looking for real info on how to do some of this stuff, and this site has been fantastic. However. :)

There are only a very few mentions of AC motors and battery technologies which are not lead-acid. I see posts and glossary terms for what appear to be newer technologies but not Lithium Polymer nor NiCd.


Is there a section on these things which I'm missing? What I want to know is whether it's feasible to set up an electric car with 3-phase AC when you're a garage mechanic. I understand how 3-phase works, and I've had slight exposure to brushless DC in models.

If this site doesn't have any info on that, could someone point me toward a site which does?

It seems to me that the main wiki page could stand to link to comparisons in terms of performance and cost and difficulty to assemble. I would really like to try that for the first car (still looking for a donor) but I won't try it as a first-time if I'll be fighting uphill.

Thanks.
 
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#6 ·
I don't mean to be troublesome, but that's not a helpful answer. Also keep in mind that I'm not trying to flame you or anyone else, only trying to get information. If my post comes across as aggressive or negative, then please know it was not intended to be that way.

I'm hoping for a section of the wiki which shows an organized presentation of what you need to know in order to make a 3-phase conversion similar to what is on the wiki for DC. Better yet would be for the existing wiki to compare AC and DC procedures such that I can make my choice after having seen the issues.

Let me make sure everyone knows I found the wiki VERY helpful. I have never seen such a well organized presentation of hands-on, garage mechanic-oriented information on converting a car. I feel that I can now intelligently ask questions about DC conversions and not feel like a moron.

If I had the slightest idea how to approach an AC conversion I would volunteer to help organize the wiki such that AC topics are integrated into the existing pages in appropriate places. I don't have any idea about the topic though, so I am hoping for either a link to a page which I did not find or for a link to some other site which focuses on this.


Searching on "3-phase" gets me a whole lot of details-oriented questions like programming homemade motor controllers with a safety pin and a converted toaster oven. I'm not anywhere near ready to design my own controller yet. I'm looking for a first conversion and hoping to be exposed to AC at the same time.

Thank you for your time.
 
#12 ·
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...
 
#8 · (Edited)
I don't mean to be troublesome, but that's not a helpful answer. Also keep in mind that I'm not trying to flame you or anyone else, only trying to get information. If my post comes across as aggressive or negative, then please know it was not intended to be that way
You're just being a tad lazy. We've all done tons of research over the last year... you can too. Just asking people for all the information is easy, but its already been covered, many times. My post is just trying to get you to research a little. Not meant to be mean, but there is a search bar for a reason. I know my answer wasn't what you wanted... you wanted the easy answer all in one.

I'm hoping for a section of the wiki which shows an organized presentation of what you need to know in order to make a 3-phase conversion similar to what is on the wiki for DC. Better yet would be for the existing wiki to compare AC and DC procedures such that I can make my choice after having seen the issues.
There just aren't a TON of AC systems out there yet for people to do wiki's on them. People do blog about their conversions of AC systems, so maybe this site isn't the best, but go to google blog search.

http://blogsearch.google.com/

and check out evalbum AC conversions:

http://www.evalbum.com/mtrtp/AC3P


Let me make sure everyone knows I found the wiki VERY helpful. I have never seen such a well organized presentation of hands-on, garage mechanic-oriented information on converting a car. I feel that I can now intelligently ask questions about DC conversions and not feel like a moron.
I agree, it was very well put together. I sometimes wish there was an AC, but there's not a ton out there on wiki's, but there's a ton on blogs like this:
http://www.roadglue.com/wiki/index.php/Electric_Conversions


If I had the slightest idea how to approach an AC conversion I would volunteer to help organize the wiki such that AC topics are integrated into the existing pages in appropriate places. I don't have any idea about the topic though, so I am hoping for either a link to a page which I did not find or for a link to some other site which focuses on this.
keep links of everything you find, and post to the wiki... it IS a wiki afterall.
 
#9 ·
You're just being a tad lazy. We've all done tons of research over the last year... you can too. Just asking people for all the information is easy, but its already been covered, many times. My post is just trying to get you to research a little. Not meant to be mean, but there is a search bar for a reason. I know my answer wasn't what you wanted... you wanted the easy answer all in one.
Yes and no. Yes, I want it all in one spot. Yes, if all I wanted to do is find out about 3-phase AC conversions then it would be lazy. However, I bet there are a whole lot of lurkers out there who want to see exactly what I'm after. Finding out if the page I want exists is the first step. If I find enough to make the wiki entry then I'll make it or cooperate in making one if someone else has already started.

I agree, it was very well put together. I sometimes wish there was an AC, but there's not a ton out there on wiki's, but there's a ton on blogs like this:
http://www.roadglue.com/wiki/index.php/Electric_Conversions
Fair enough.


keep links of everything you find, and post to the wiki... it IS a wiki after all.
I intend to, and you gave me a lot of info on this post to check out.
 
#10 ·
1clue. As has been said, there isn't much info out there. I REALLY wanted an AC drive. I REALLY wanted regen. I GAVE UP temporarily. For one thing, the cheapest cost for an AC system I could find for an S10 that could keep up with a moped was $9000. That was a motor, controller and cables from http://www.electroauto.com/ I'm getting a DC system consisting of basically the same parts for about $3000.

I just can't see spending three times the DC price for 10-15% better mileage due to regen. That's the reason there are very few systems in operation and thus the lack of info.

Best of luck though!
 
#11 ·
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. :)
 
#15 ·
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.
 
#17 ·
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.
 
#18 ·
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. :D
 
#19 ·
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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