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Forum Index : Windmills : Low Starting Torque &Friction Alternator!
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| mechamz Newbie  Joined: 29/06/2008 Location: Posts: 11 |
Hi, I'm currently doing a VAWT prototype. I'm happened to find these 2 alternators, but not sure which is better? http://www.ginlong.com/wind-turbine-pmg-pma-permanent-magnet -generator-alternator-GL-PMG-500A.htm http://www.windbluepower.com/DC_540_Low_Wind_Permanent_Magne t_Alternator_p/dc-540.htm the dimension of the Savonius turbine, height is 0.8m and width is 0.43m My system require a low starting torque and low friction alternator. Previously, I've purchased one from http://energistar.com, but the performance was far from the information given. I hope the alternator able to generate 12V and more than 1 or 2Ampere at low rpm, and low torque required. Any better suggestion than these 2 alternators are welcomed. or something like this, http://www.gotwind.org/diy/Axial_Flux_Alternator.htm Any idea?? Fixed those links for you. Gizmo. http://www.ginlong.com/wind-turbine-pmg-pma-permanent-magnet -generator-alternator-GL-PMG-500A.htm http://www.windbluepower.com/DC_540_Low_Wind_Permanent_Magne t_Alternator_p/dc-540.htm I'm looking for an alternator(low rpm) pm me please |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5117 |
Both of those altenators are way way to big for that size turbine. A 0.8m X 0.43m sav will only give a frontal area of 0.344m ,and that will only be good for a few watts. Using Power = 0.615 x Swept Area x (Velocity)³ I get about 13 watts in 4ms wind. ( See http://www.small-farm-permaculture-and-sustainable-living.co m/windmill_power.html ) 13 watts isnt a lot of power to drive those big alternators, most of that would be lost in just the bearings alone. What about a stepper motor? A sav' windmill has lots of startup torque, it should work well on a large stepper motor. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi mechamz, The power levels that you are talking about are very low. The current will determine the wire thickness. The rpm will determine the number of poles[magnets] and the number of turns needed to generate the required EMF. An iron cored alternator will sap much of the power you are trying to capture. Low rpm usually means a large number of poles and this would require a large iron mass to complete the magnetic field. I would opt for an ironless design. If you do not want to build your own, Maxon[Switzerland] do make a range of basket wound ironless motors, that could be used as a generator. They make a wide variety of types and operating power ranges. They are reasonably expensive. They have very low inertia. Good luck. Gordon. become more energy aware |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5117 |
We keep doing this Gordon, posting at the same time. I beat you today by 3 minutes! The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
No worries Gizmo, I was busy on another post, so didn't check first. The maxon motors have the highest efficiency of any small motors that I have tested. I used one in my first model solar car. Approx efficiency is above 80%. The closest iron cored small motor was around 50% efficiency. They are high torque as well. I remember pulling a similar basket wound motor from a VCR. Gordon. become more energy aware |
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vawtman Senior Member Joined: 14/09/2006 Location: United StatesPosts: 146 |
http://www.windstuffnow.com/main/3phase_turbine_kit.htm What about something like this from Ed.May have to beef it up a bit  |
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| Dinges Senior Member Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
That generator looks vaguely familiar... http://www.fieldlines.com/story/2005/11/13/32021/791 Anyway, Mechamz, you can find more construction information in the link above. I don't think I'd go with anything else but an axial flux for your particular application. Edit: some more pictures can be found here: http://www.anotherpower.com/gallery/album46 |
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| mechamz Newbie Joined: 29/06/2008 Location: Posts: 11 |
yeah, but where/how can I buy Axial Flux Alternator?? or any dynamo with higher power?? I'm looking for an alternator(low rpm) pm me please |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5117 |
Hi mechamz I'm not sure you realise how little power you will get from that windmill. Remember, based on the sizes you gave us, you only have about 13 watts in average winds. Using a higher rating alternator wont give you more power. I doubt there would be a commercial alternator available for such a small windmill, you really need to make your own as suggested above. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| mechamz Newbie Joined: 29/06/2008 Location: Posts: 11 |
could you provide any links? thanks I'm looking for an alternator(low rpm) pm me please |
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| mechamz Newbie Joined: 29/06/2008 Location: Posts: 11 |
yeah, I know that. I will try this wind turbine under relatively strong wind, around 5-6m/s I'm looking for an alternator(low rpm) pm me please |
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| Dinges Senior Member Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
The best things in life are not for sale... At least I don't know of a place that sells small axial fluxes. Probably the only way to get one would be to build one, just as everyone else here seems to do. Maybe you can get someone to build one for you, but keep in mind it took about 30-40 hours of work to build that small axial flux. Multiply with an applicable hourly rate for someone to do the work for you... And suddenly that Maxon motor Gordon pointed you to actually appears to be dirt cheap in comparison... Funny thing is: it takes about the same amount of time, effort and material costs to build such a tiny axial flux as it takes a full-sized one. Which is the reason hardly anyone messes with small toy stuff, it's just not economical. |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi mechamz, This link is the maxonmotor shop. You will need to select the type of motor, EC flat type, and the power. Select the 90W version. The 48V motor has 2000rpm speed. https://shop.maxonmotor.com/ishop/app The power range would be about 30W@600rpm. These are mini F&P motors. A simple search found this one. I am sure you could have found this just as easily. Gordon. become more energy aware |
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| mechamz Newbie Joined: 29/06/2008 Location: Posts: 11 |
agreed. I'm looking someone do it for me. I'm willing pay for it. anyone interested?? thanks I'm looking for an alternator(low rpm) pm me please |
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| mechamz Newbie Joined: 29/06/2008 Location: Posts: 11 |
but I have to find a suitable one to suit my wind turbine =( I'm looking for an alternator(low rpm) pm me please |
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