# PM motor !!!



## epyon (Mar 20, 2008)

Does any body have one , used one , build or building one ? I'll even throw in brushless motors . Any bad issues with them ? Any good ? I'm on the way to build a big PM motor and would like some feed back to help my motor work better . Any car that you have or had or someone I can contact about there car if possable . Thanks to any help in advance . The people I'm working with or shooting for the moon , but I'm not rich , so it will take time .


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## kennybobby (Aug 10, 2012)

1. how much torque do you need? 

2. what speed (rpm) do you need? 

3. what is the duty cycle of operation (continuous or short bursts)? 

4. how much energy is in your battery pack? what voltage? what is capacity (Ahr)? 

5. how much space (volume) is available? 

These are some of the things to help determine if a PM motor is a good solution.


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## PStechPaul (May 1, 2012)

I would question why you want to build a large PM motor (or any motor, for that matter), when you can purchase usable motors of almost any size for close to scrap value. As an educational experience it may be valuable to build small models of various types of motors, and you can find lots of examples on YouTube or on-line tutorials. Also do some reading of various textbooks on basic motor theory. The best book I have is:
http://www.amazon.com/Electric-Motors-Control-Techniques-Gottlieb/dp/0070240124/ref=pd_bxgy_b_text_y

Personally I prefer three phase AC induction motors for EVs, even for small ones like bikes and tractors, but PM DC motors are a good fit for many applications, and are somewhat simpler and easier to control.

Be aware that there is a lot of misinformation on the web about ultra-efficient and even free energy motors but don't be misled by their starry-eyed claims and clever "proof" of concepts. Motors generally are 70% to 96% efficient and about 10 pounds per horsepower. Provide more details about what you want to do and you will get good advice. Good luck, and welcome..


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## epyon (Mar 20, 2008)

Controlling a AC motor takes lots of money , an a DC does not . A Shiva is less thenany thing from Rienheart . But what Dc and or brushless motors have you worked with .


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## Ivansgarage (Sep 3, 2011)

epyon said:


> Controlling a AC motor takes lots of money , an a DC does not . A Shiva is less thenany thing from Rienheart . But what Dc and or brushless motors have you worked with .


Rienheart??? have you seen Curtis Controllers??

http://curtisinstruments.com/index.cfm?fuseaction=ProductsGrid.ACMotorControllers


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## major (Apr 4, 2008)

Ivansgarage said:


> Rienheart??? have you seen Curtis Controllers??
> 
> http://curtisinstruments.com/index.cfm?fuseaction=ProductsGrid.ACMotorControllers


Have you seen an AC Curtis work with a PM motor?


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## Ivansgarage (Sep 3, 2011)

major said:


> Have you seen an AC Curtis work with a PM motor?


Originally Posted by epyon 
Controlling a AC motor takes lots of money.

boy major you can really be nit picky


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## major (Apr 4, 2008)

Ivansgarage said:


> Originally Posted by epyon
> Controlling a AC motor takes lots of money.
> 
> boy major you can really be nit picky


Title of this thread is *PM* motor !!!

Nit picky? Just trying to make sense out of your post


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## epyon (Mar 20, 2008)

Not trying to dump on any body here . But from talking to people that know more then me , a AC motor that can get near my goals can't be done without to much money . I am just trying to see if anyone has any tips on a big PM motor for a electric car . Hpevs said that they would'nt tune the controllers for me on a motors near what I want . I have not done nothing to these two big motors yet .


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## epyon (Mar 20, 2008)

Oh crap , almost forgot . I droped a motor off to begin with , to see if my plan will work on the windings and then go from there . And the power and speed I'm looking for is 400Ft lbs and 5,000 rpm in the end .But it must be able to run very good at 48-72 volts an 400 -800 amps to test . An then go to a Solution Jr and 310 volts .


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## tylerwatts (Feb 9, 2012)

Epyon, just to clarify for myself and others you are talking about a brushed pm motor right? Like a really big Lynch or agni motor? That does sound like site of torque but with isn't beefy pm magnets and the right rotor diameter should be no problem. 

I'm working on an axial pm motor. If designed right it would work well. But I don't see any pros bar a little more torque for your amps as you're putting it all into one half of the motor only. But weight, cost, complexity and the hassle of development for a one off make no sense. It would cost more than any Warp or Kostov combo/setup would. 

Although one positive idea would be to use one of those rotor's or entire motor housing and inset custom magnets. Though the amount of amps would be limited as you are now not sharing it between the two halves of the motor. I personally prefer the Kostov interpoled motor rotor to be honest, you could easily reverse polarity for reverse motion, and it is lighter and faster also (higher rpm, faster spool up).

Actually for interest's sake this seems like a cool project though not a cost saving one. Simple logic (whether sound or not) seems to say a pm motor will be more power dense. A Soliton jr could perform as well as it's big brother would on a stock Kostov. 

And the real benefit for us DIYers is the simplicity of the controller. Hey I'm almost convincing myself this could be a better project for me. Shucks, why'd I open my trap?!


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## tylerwatts (Feb 9, 2012)

Epyon are you saying in your last post you have a motor? Do tell about it please! Spec, photos etc.


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## epyon (Mar 20, 2008)

I didnt take pictures of the motor before I droped it off , sorry . But it started out as a 20 hp GE 400+ volt AC pump motor . I'm testing on this motor because it has no cooling finnes on it . Damm tylorwatts , your scary close to my thoughts on a motor . Guess my tin foil dosen't work .


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## tylerwatts (Feb 9, 2012)

Well we await it's return sir! How long until you have it tested? 

How did you construct the motor? What have you changed? It is a very interesting project. 

Great minds, as they say, think alike


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## epyon (Mar 20, 2008)

I"ll be able to takee pictures because the manager didn't want to start a project like mine . But the guy that would have done my motor said the manager just didn't get it . I am not gonna give the secret of the motors away . But I will say that it will not have brushes an it will have magnets . What I will say , if I could make a new PMDC rc car style motor , turning 20,000 RPM and 400Ft lbs of Tq would make me mess my paints . And that would be more of a machine shop style job .


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## tylerwatts (Feb 9, 2012)

Epyon you say you will take pictures but your post suggests you cannot. Which? Do you have any specs please? 

I think the engineering and cost of a 400lbft 20krpm motor would be too high! One or the other would be plenty suitable for a 2-3000lb car with great performance. You should not need more than 10krpm and that much torque, and a single speed reduction. At this you'd need even less torque. I'm working on 150lbft and 12krpm with a 10:1 reduction and big wheels giving 80mph @ 1000 wheel rpm and 10000 motor rpm.


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## epyon (Mar 20, 2008)

tylerwatts said:


> . I'm working on 150lbft and 12krpm with a 10:1 reduction and big wheels giving 80mph @ 1000 wheel rpm and 10000 motor rpm.


What motor are you using ? An those are just wet dream numbers .


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## tylerwatts (Feb 9, 2012)

Those are the specs I am trying to design an axial Flux permanent magnet AC motor to meet. I don't see why it is not possible if I am designing for it. I am not looking for an existing motor. It is probably not far off oe spec AC motors like in the Volt/Ampera.

Have you got pics or updates on your motor?


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## epyon (Mar 20, 2008)

This is the gine pig . An I hope I didn't type it wrong when I said dream numbers , because I ment that for my motor , not yours . If it works the way I plane , the next motor will do 950 Ft Lbs of "touque" and 9,500 RPM's .


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## sirwattsalot (Aug 27, 2012)

I have always been interested in PM motors because simply using powerful rare Earth magnets can make a very powerful motor. The problem is that they always get very hot when you push them to the limit. The Mars, E-tech, or Manta PM motors use powerful rare Earth magnets, but they are too small for a car. They are just perfect for a boat or motorcycle. Perhaps two of the Mars could run a small car- maybe. I did use one that had a double set of brushes at 72 volts to run my Saturn up to 45 miles per hour and the motor was smoking when I returned home. I was amazed at how little it had discharged the six lead acid car batteries that powered it. I put a total of ten miles on the odometer with a lot of starts and stops. I could have driven the car a long way farther if the smoke had not caused me alarm. I will never know just how much farther it would have gone. I have wondered since what would have been the result if I had run two of those PM motors while accelerating and then turned one of them off to cruise at 55; kind of like running on 6 cylinders and then only 2. Accelerating is what draws the most current from the batteries and also what heats up the motor as I have discovered by driving my own car. 
You are correct, the DC motors are typically less expensive, however I am now using an AC-50 3 phase motor which performs very well. The cost is much higher. Still, well worth it because, it does not get hot and the controller stays cool also.
I have discovered that I can cruise on 125 amps at 110 volts, but it requires up to 500 amps (4 x the power) to accelerate up to 55 in a timely manner. The range of the car has been limited, but there has not been any problems with overheating. I am replacing the lead acid batteries with some of the best Lithium Iron Phosphate batteries which will weight about 200 lbs. less and pack 2.5 times the energy. They are not cheap, but again, well worth it. 
What is most important is that you have fun, stay safe, and never give up faith in your own objectives. You are not building this to please anyone else. I have put my car together and have taken it apart 4 times now to make it what I want it to be. I have spent a lot of extra money experimenting and I would do it all over again without any regrets.


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## PStechPaul (May 1, 2012)

Seems like you have come a long way and have learned a lot from your builds. But the only thing I would question is your thought that you could use two of the PM motors for acceleration and then disconnect one for cruising. To get the same power from one motor, you would need twice the current used by each of the two motors. Since losses are mostly resistive, you would have four times the losses, but since you have one motor and not two, your total losses would still be doubled. For this reason, it is generally better to use a larger motor (or multiple smaller ones) to stay well within the rated power, or even much less. The downside is larger size and weight, but at some point you may be able to go direct drive and eliminate the transmission and clutch.


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## mizlplix (May 1, 2011)

Has anyone done or know of someone who has actually done, a conversion of a large AC induction motor to magnets?

I have read of smaller sizes, but no large ones...say 10HP or above.

Thx, Miz


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## hal2000 (Nov 15, 2012)

Arlo over on endless sphere is playing around with fem in an effort to convert a large ac motor over to a large pm motor for use in his detroit muscle car. Poke around in the motor threads and I think you will find the link.


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