By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Car Alternator as Traction motor?

All Topics | Latest Posts

Search for:  in Thread Title in  
Peter Bell18/11/2011 15:25:40
399 forum posts
167 photos

Had an enjoyable browse through the Model Engineer in the library this morning and was interested to read that a talk will be given by Bob Walker on brushless motors at the ME exhibition.
But what really made my ears prick up is that one of the topics he will be covering will be using a car alternator (16ARC) as a three phase traction motor with a continous rating of 950watts.
 
Cannot attend the exhibition so wont be able to hear the talk direct and just wondered if anyone has hear of this technique before?
 
Thanks Peter
Andrew Johnston18/11/2011 16:01:19
avatar
7061 forum posts
719 photos
It's fairly common in cars that have a 'stop-start' system to use a single electrical machine as both starter motor and alternator. In simple terms a three phase electrical machine can act equally well as a motor or generator. I would have thought that 950W isn't a problem. One of the reasons for the push to 48V SLI (starting, lighting, ignition) car systems was that the loads were pushing beyond a kilowatt; which is loadsa amps at 12V.
 
Regards,
 
Andrew
DMB18/11/2011 16:17:23
1585 forum posts
1 photos
I was told sometime ago that Rolls-Royces have a combined alternator/starter motor system. This means that the device is permanently engaged with the engine, resulting in silent starting, eliminating the terrible screech when the Bendix mechanism operates for starting most other cars. Also, there is a `slave` battery in the boot.
Perhaps one of the wealthier forum members with such a machine, can confirm the above.
Peter Bell18/11/2011 16:27:47
399 forum posts
167 photos

I recently read that the stop start technology now extends to motor cycles. I suppose it's the same reason why most commercial vehicles are 24 volt, under the bonnet on the stop/start car I looked at it certainly seems tight with 48volts.
 
What I was interested in really is about using some readily available technology to drive the alternator and it did cross my mind the that perhaps the person who is giving the talk has written a book on it or is know to this forum or even appears on it?
 
Regards Peter
Billy Mills18/11/2011 16:37:49
377 forum posts
The motor demo has been at MEX. It is a great idea, the car alternator has three delta wired windings so you can drive it from a variable frequency drive as a variable speed motor. The VFD was made from a couple of IC's and 6 Mosfets. The designer had a very nice demo rig on show.
 
As the rotor is designed for a 12V system the voltages for motor use are conveniently low. The idea of 2 or 3 phase drive of very small motors is widespread in electric flight. Some of the early pioneers rewound floppy drive motors. The power to weight ratio of these motors ( with rare earth magnets) is very high at about a HP per pound weight.
 
Billy.
Billy Mills18/11/2011 16:49:01
377 forum posts
Rollers do have two accumulators. When your driver is waiting for you he can run the electrics without the engine running. The other battery will always be able to start the engine.
The combined motor/generator idea is described in a book called "Modern Starting,Lighting and ignition systems" it was published in 1917.
 
Billy.
Peter Bell18/11/2011 17:35:51
399 forum posts
167 photos

Billy,
It is the VFD bit that interests me really. Do you have any info about it or what the electric flight motors use. Or is there another forum which covers it?
 
Just been playing about with a pulse width mod circuit for a solenoid and I think its the first time I have successfully used power mosfets!
 
Peter
Billy Mills18/11/2011 18:30:05
377 forum posts
You can buy the VFD's for electric flight for not very much, they run around 20-50A for flight times of 10 min or so. The VFD is very simple. An oscillator drives a counter which then outputs the phase drive signals to the mosfets via a standard IC. You do need to know about fast switching, a 100MHz scope or faster is needed to check operation properly if you were rolling your own.
Scrap PC motherboards are one source of free mosfets, motherboards don't last long these days, but heavy current mosfets are dirt cheap anyway. Have a google for electric flight Peter.
 
Billy.
Stub Mandrel18/11/2011 18:40:45
avatar
4318 forum posts
291 photos
1 articles
If anyone want details of driving BLDC (brushless DC motors) there are a couple of useful datasheets on the Atmel
 
 
 
These are a bit of heavy going, but for thiose who want to know they describe the theory of how they work OK and you DON'T need to understand the microcontroller side.
 
Neil

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Shopping Partners
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate