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Forum Index : EV's : Concept for F&P bicycle/tricycle
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| KiwiJohn Guru  Joined: 01/12/2005 Location: New ZealandPosts: 691 |
I am thinking of making an F&P powered bicycle or tricycle. For no particular reason just that there are a few F&Ps under the bench. I recall reading that Porshe (senior) made an electric about 100 years ago, he used front wheel hub motors and had a rotating drum commutator mechanism under the drivers seat! So I am thinking that a commutating system connected to the pedals would make for a very natural form of control. Although brushes and contact disks could be used as Proshe did there is probably some more modern method involving chopper disks and semi-conductors that would be more appropriate. The question is, is energising the three phases in sequence all that is required to make the motor run? Cheers |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi John. Sounds like a big project. A few years ago I was involved with a solar car team, and we planned to use a F&P as the motor. We used a dedicated controller chip designed to dive motors like the F&P, using the hall sensors to get magnet positions and switch the coils at the right time. It did work, but took many many hours and we ended up abandoning the F&P and used a high efficiency DC brush motor instead. I believe feeding 3 phase AC into a F&P, without tracking the hub position, will have unpredictable results. For example, at low speed, if the hub has loaded and runs slower than the 3 phase AC input, it could suddenly rotate backwards a few degrees. Modern electric RC planes use a 3 phase AC controller to drive a miniature F&P looking motor. They dont use hall sensors, but I think they use back emf to detect the hub position. Electric push bikes with the hub motor also use a sensor-less motor. It might be worth while looking into how these controllers work to track the hub position. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
John, Craig Carmicheal has had a go at this with an axial flux version. He originally used 555's some discrete bits and some tricky stuff, but I coaxed him into using the mc33033 chip, which solved some of the problems Gizmo alluded to. Here is the complete manual on how to do it If you can't find the mc33033, I still have a few. (I later found out that these were to be discontinued) He goes into some depth on the foibles of this kind of controller. Hope you find it interesting. .....oztules Village idiot...or... just another hack out of his depth |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi John, My black painted AxFx alternator started life as a motor for my own solar car[1996-1999], before life in a windmill. I used hall effect rotor position sensing. High efficiency and light weight are the key for automative applications. I would probably go for a brush commutator for simplicity, and rotate the coils, keeping the magnets stationery. I have tried using the sensorless electronic commutator on a F&P without success. The high "L" inductance of the stator I think was a problem. There would have to be better, lighter options. Gordon. become more energy aware |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
I did see on Utube some time back where someone used F&P motors on a cnc router with good stepping results, it could be worth a search. Pete. Sometimes it just works |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Thanks for all the comments guys, I will study that site Oztules. Gizmo, I too am unsure if just switching the coils would give predictable results. The basic concept is to use some form of commutation driven by the pedals so you have to pedal to keep it going and the motor would be a form of assistance, if the action of the motor is unpredictable it may be that the rider can learn the limits but I really dont know. One way to find out!  |
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| dwyer Guru Joined: 19/09/2005 Location: AustraliaPosts: 574 |
Hi Pete |
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