Auto Alternators As Motors

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Tinker1980

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I think the problem is to first of all "know" how many turns you need in the coils if you are to construct a motor and then (of course) being able to actually fabricate a motor from scratch
Don't want to make an entire motor. I think one could use the windings in a car alternator, and replace the rotor itself. I don't think it would be rocket surgery to remove the copper windings and armature from the shaft, and replace it with stacked steel laminations. All of the laminations, except for the ones on the end, would be the same, and you'd then just need 10-12 copper or aluminum rods.
 

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safe

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This is true...

You might take a look over at the Dishwasher thread... Frigidaire seems to be making a Three Phase induction motor that looks good.

Alternators aren't the only avenue to look at.
 
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Tinker1980

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The dishwasher motor looks interesting... the reason I am interested in alternators as motors is because there are far more junk alternators to be found than junk high-end frigidaire dishwashers. (But of course I work for the Competition, and consider anything that frigidaire makes as junk:whistle:)

-Mark
 

safe

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The biggest problem with starting with an alternator motor is that it's actually a synchronous motor, not an induction motor. So before you even begin to deal with all the problems of frequency control, current control and the probable wrongly sized wires in the coils you have to change the alternator to something it isn't.

I see no value whatsoever in using a synchronous motor. A permanent magnet motor achieves the same result and with better efficiency. The real advantage of the induction motor is the fact that it does better with full load across the motors powerband than do the "fixed rpm" motors. Permanent magnet and synchronous motors only work well at one specific rpm, so you have to use gears to make them useful.

One wonders if Frigidaire is the only appliance motor that is Three Phase. My searching has produced the fact that all the Frigidaire dishwashers after 2000 use the Three Phase design and before 2000 it was a permanent magnet. So I think there are probably post-2000 dishwashers in the junkyard somewhere to start with.

Even brand new on ebay you can get them for $88 or less.

Alternators are good too. (more work though)

From my perspective when I learned that the alternator was a synchronous motor it pretty much ended my interest in it. When my dishwasher failed I started off looking at it as a Single Phase motor as a possibility... and that's still something to consider... but Three Phase is better.

I like the idea of being able to have a nearly unlimited powerband width at full throttle... if you could achieve that on an ebike then you could actually go without the gearing without sacrificing performance. I want the 1000 watts of input power to be able to be equally distributed as power output from zero up to about 50 mph. The permanent magnet simply can't do a good job of that based on the physics of how they work. To get an ebike to go past about 30 mph with a permanent magnet you need gears or more power.

If I were to sell the ebike as a product then I could design the controller with a top speed cutoff. So maybe you sell the bike and the controller automatically limits the speed to 20 mph to satisfy the Federal Ebike Law and avoid lawsuits. The buyer then finds ways to get around the law (aftermarket controller, etc) to get the bike up to higher speeds.

Many states allow 30 mph anyway... so the bike could be sold with a "30 mph chip" in states that allow it.

Anyway, the foundation for all of this "folly" is to get an induction motor to work for an ebike as the "Holy Grail". Somehow it needs to be possible.

Crazy dreams about fun ideas are better than nightmares... which is how I feel these days working to fix up my house. I'm kind of at the point of complete disgust with owning a big house. Too much maintenance and repairs and cleaning to deal with all the time. Given the choice I'd like to just devote my time to fun research projects.
 
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safe

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I'm not sure if you read the thread or not, but the overall view ended up being that they don't make good motors.

An Alternator needs it's field coils to be charged up manually in order to produce power. Running as an alternator that increases the ability for low rpms to be able to create larger fields than could be done otherwise, but there is no advantage to that when used as a motor.

The "bottom line" was that you would be better off with a regular permanent magnet motor.

There was a guy just recently that is making a "hybrid" that used an alternator and got the power from a gas powered motor. We haven't heard anything for a while.... I wonder how that turned out. :unsure:
 

safe

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High Performance Permanent Magnet Alternator

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280397202547&ssPageName=STRK:MEWAX:IT

...as mentioned above, yes, these permanent magnet alternators could actually make pretty good ebike motors.



Since they are using 14 poles in the rotor this in effect "gears down" the motor rpm so that fewer rpms are needed to create useful power. For someone that wants a very powerful motor that weighs 10 lbs and can be used WITHOUT a geardown unit this could be a great solution.

You could directly connect this to your bottom bracket with a chain. :cool:

The price is steep... $289. :cry:
 
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spad4me

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High Performance Permanent Magnet Alternator

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280397202547&ssPageName=STRK:MEWAX:IT

...as mentioned above, yes, these permanent magnet alternators could actually make pretty good ebike motors.



Since they are using 14 poles in the rotor this in effect "gears down" the motor rpm so that fewer rpms are needed to create useful power. For someone that wants a very powerful motor that weighs 10 lbs and can be used WITHOUT a geardown unit this could be a great solution.

You could directly connect this to your bottom bracket with a chain. :cool:

The price is steep... $289. :cry:


NO ONE has built a hydrogen appliances alternator motor YET. I have looked. A lot of people have tried.

The site also states that about 500 watts is all you can expose the windings to in one of these Windmill modified alternators..Without special cooling.

Cheaper to try a regular alternator .
With 3 to 6 volts through the rotor windings and either a castle creations sensorless controller.
about 175 dollars, or an ecrazymans hall effect controller about 50 dollars with a hall board and hall sensors about 50 dollars .

I have also looked at this rotor excitation method.

http://www.linux-host.org/energy/salternat.htm

near the bottom of the page.

You will blow contrrrrrrrrrollers like popcorn at 100 t0 200 dollars a POP. OUCH!!
GOOD LUCK you will need deep pockets.
 
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safe

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The site also states that about 500 watts is all you can expose the windings to in one of these Windmill modified alternators..Without special cooling.
Didn't see that... yes... that's not good.

Also, from my AC Induction motor studies I've learned that when you increase the pole count (in this case 14 magnets verses the usual 4 magnets for a typical brushed motor) that increase causes more "confusion" for the magnetic flux field lines and that means more eddy currents and more heat losses. So as you increase the practicality of a motor with more poles (slower speed) you lose efficiency as you do it.

In my opinion you either stick with the basics and go with a simple permanent magnet motor (brushed or brushless) and then work out the geardown units and the multispeed gearing. Or if you think that's too messy then you experiment with an AC Induction motor like I'm doing... but I can say that the "experiment" is not easy. The reason to go for the AC Induction motor is that the powerband width can expand to three times that of a permanent magnet motor and that means no need for gears. (you can actually run a one speed)

There's just a point where "keeping it simple" is the smarter way to go...

(but it can't hurt to fool around with an alternator if that's something you feel like doing)

The lingering question is of what value the field current becomes when you no longer need it for a motor? (it's sort of a wasted thing to have)
 
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