Mar 13, 2019, 01:15 PM
Drew RT
Help!

# low kV alt (0.13) 3D printed axial flux PMA/M, using poured structure

Hello RCgroups

I'm looking for some advice on a couple of subjects. I'm not an engineer, nor do I have any real technical training, which means I don't always understand some of the terminology used by experts. I may not have understood kV properly, but I'm aiming for a system that produces 12V at 100rpm, and right now I'm at around 5V at 200.

First thing I'd love to hear some comments on is my alternator design in general, and what effect going from an 8 pole to 16 pole (halving magnet size, so keeping magnet volume the same), might do.

Second thing, I'm wondering about using the brake (regenerative) feature on an RC ESC as my load controller on a mini wind turbine project. What I need to do this is to be able to increase the load, non-linear with the speed. As wind speed doubles, wind energy available cubes, while turbine speed only doubles.

This is usually accomplished with a programmed data table, at rpm "A" set load to 1%, at "B" set load to 8% at rpm ''C" set load to 64%.

What I'm thinking is that by using an arduino I could measure rpm and generate a signal for the controller to adjust the brake load? Perhaps it could all even be done inside the controller. I've been looking at the Castle Creations controllers and it seems like they might be a good fit.

A video of it blowing an LED (post rectifier) after being spun by hand is here

### Images

Mar 14, 2019, 11:38 AM
Drew RT

# combined Volt Amp data against resistive loads

I realized after posting that none of these files had both V and A data, while the turbine was loaded, so I've added a file with unrectified V, and rectified V and A. I've done a bunch of calculations, which I've tried to show, but I'm not sure they mean much given that my voltage is so low and the rectification losses so high. I am looking at doubling the magnets in my array to up the output.

I think I'll set this up, driven by a cordless drill motor (with gears) for the next round of testing. I should be able to set it up so that I can have the drill motor mounted to a lever arm, so I can read real torque in, and see the difference between shaft input and electrical output.

### Files

Last edited by drewrt; Mar 14, 2019 at 12:18 PM. Reason: added details about future testing
 Mar 15, 2019, 01:37 AM Suspended Account Hello Drew, Why are you after more magnets versus changing the turn count for more voltage? Alternative energy project?
 Mar 15, 2019, 12:58 PM Drew RT Thread OP Hi 1boho, I had a lot of trouble fitting the end winding in and keeping it packed, and was uncomfortably aware that in this winding, my end winding is more volume than the active portion of the winding. If I doubled the pole count, I'd change the proportions of end winding to active winding, I think? It would be more complex to wind, but I'm OK with that. I didn't see it before I started, but now I see that in axial flux design, small diameter works better with higher pole count, again, I think. I have a wealth of 1x1x025" magnets, so that's what I started with. I'm just rebuilding it now with a double stack of magnets, and using steel wool, in addition to the wire which forms the magnetic backing plate. The single layer of heavy wire, according to my magnetic visualization film, isn't providing much flux coupling. I'm also making the poured void about 5mm thicker for more strength, as I'm afraid the doubled magnets might pull it apart. Yes alternative energy project, VAWT, but I find so many people are so anti VAWT (for good reason, so much hype, so little delivery), that I keep that side to myself when talking about the electronics. It also might make a very nice little direct drive lathe motor for truing up prints, or a pedal powered alt. And, while it is for a VAWT project, it also seems well sized to fill a hole in the idea market for a small PMA/M that is fairly close to human scale output.
 Mar 15, 2019, 03:23 PM Suspended Account People are resistive like that for money n some cases and because great alternative energy projects require efficient designs and they haven't the know how to make it deliver as promised. I don't think cogging motor designs are ideal for generators. I also like inertial pulse motor that rectify the inertia driven BEMF into storage like lithium super capacitors. What would be nice is a large nickel zinc storage system or \$ilver Oxide. Really cool project you got going. Keep the updates flowing. Last edited by 1boho; Mar 15, 2019 at 04:08 PM.
 Jul 14, 2019, 05:00 PM Drew RT Thread OP Hello to you all! I just put up an "instructable" on my Axial Flux design. It's less of a "how to", and more of a "here's some things I tried, and how they worked. I does work, but I'm not sure that my test system is functioning well enough to measure it's efficiency, and that doesn't actually matter to much for my project at this stage. I'm trying to measure the output of a VAWT design (inspired in part by Barnaby Wainfan's Faucetmobile). What I've done is set it up so that I can measure mechanical torque produced at the point the base connects with the mount, and I can at the same time measure turbine velocity. From that I get real shaft power. https://www.instructables.com/id/3D-...ux-Alternator/
 Jul 14, 2019, 05:01 PM Drew RT Thread OP Hello to you all! I just put up an "instructable" on my Axial Flux design. It's less of a "how to", and more of a "here's some things I tried, and how they worked. I does work, but I'm not sure that my test system is functioning well enough to measure it's efficiency, and that doesn't actually matter to much for my project at this stage. I'm trying to measure the output of a VAWT design (inspired in part by Barnaby Wainfan's Faucetmobile). What I've done is set it up so that I can measure mechanical torque produced at the point the base connects with the mount, and I can at the same time measure turbine velocity. From that I get real shaft power. https://www.instructables.com/id/3D-...ux-Alternator/
 Aug 10, 2019, 06:06 PM Unregistered User Hi drewrt, Have you seen this YouTube channel? https://www.youtube.com/user/TheTrueGoofy Despite the name you see here as the URL, it's actually a channel about 3D printed motors. He's done some amazing work. There might be something of relevance to what you're doing. His name is Christoph Laimer. Last edited by vimy g eaou; Aug 10, 2019 at 06:15 PM.