My small wind generator build

[jwxr7]

I've wanted to build a wind turbine for most of my life. A few months ago I was browsing the web and decided to see what small grid tie inverters were available. There are now many choices under 1kw for low dollars. After seeing them I was inspired to begin planning and designing. My goal was to stay small, around 500 watts max, to keep things cheap and easy to manage.

First I had to find or build a generator that would work at that power range at an rpm that works in a direct drive configuration. I almost decided to build my own from scratch but then I found a motor at work that tested well for my purposes. My boss and owner of said motor, agreed to trade it to me for an old SWR meter I didn't need. The power curve I measured testing this motor as a generator prompted me to buy blades rather than carve my own since the rpms will be a bit on the high side.

I'll try to post some pics soon

[jwxr7]

I found a generator, so moved on and built the tower top chassis. It's just tack welded for now. I used 2" sch40 steel pipe for the yaw bearing, but it fit too loosley over the 1.5" sch40 I plan to use for the tower. I ended up machining some plain bearing rings for a better fit. The rest of the parts were scraps or wierd pieces we had lying around. I was going to try using some kind of twin tail with one side spring loaded for furling.

I ended up going with a known design that is reliable and predictable with calculations. TheBackShed.com - Furling


these guys have lots of info on this furling design too.
http://www.otherpower.com/

[jwxr7]

My plan has been to use a rooftop mount setup to save on tower structure and wire run. My pole barn seems to catch pretty good wind and I can run the wires down into the barn to the inverter.

While I was trolling for the right auction for blades I built a mini windmill. I used a plastic boxfan blade and a spindle from a mower deck, mounted it on a portable structure for testing. It works well, I can see the direction and relative speed of the wind by just glancing out the window.


I've tried it in a few places, and the picture shows my favorite so far. It's at the west end of the roof.

[jwxr7]

I finally won a set of blades and hub. There are 6 blades made from a type of fiber filled plastic, designed to spin up to 2000 rpms or more.

The diameter is around 5ft and the hub will allow me to try 2, 3, or 6 blades.

The pics show where I currently am. I just made an adapter so the hub would fit the shaft of my motor.

I still need to buy the tower pipe and do some testing to make the tail fin with the correct mass to furl at the wind speed I decide on. The furling is more for inverter and generator protection than for the blades. All the designs I've seen using these blade don't use any furling. They are supposedly pretty durable blades.

After some testing I will decide which grid tie inverter to go with. So far I have my eye on a nice 400watt one with a low startup voltage. I have an arduino that I plan to attempt to use for load control eventually.

[jwxr7]

I was thinking of making a test rig that will attatch to my truck. That way I can prove it out before buying the tower and cutting a hole in the barn roof.

[Daox]

Wow, looks like you've put some real time and effort into this already. Its looking good.

How far above the barn will you mount the turbine?

[jwxr7]

How far above the barn will you mount the turbine?

I'm not sure yet, but most likely less than 10 feet. Probably closer to 5 or 6 feet. I found a local pipe supplier that has a 17 foot piece of 1.5" for a reasonable price. I need a minimum of 6 feet of pipe under the roof deck so i can clamp it to as much of the roof truss as possible. That leaves plenty to go above if I choose, as long as I can manage the extra forces from a taller above roof extension. I'll have to do some experimenting, plus my roof needs redone badly on the barn. That may take priority at the moment .

[jwxr7]

I'm finishing up replacing all the rusted out brake lines on my truck, so I'm begining to design a wind turbine test rig to go on or in it. I'd like it up front where the wind will be clean, but there isn't a real easy way to mount things up there. I've seen rigs mounted in the bed with the rotor up above the cab a bit, this will be easier. I also saw one that had the pole coming up from the rear bumper hitch area with the rotor above cab height some. I'll probably go with the in bed version since I know I can make a good strong mount out of my favorite prototyping medium, lumber and drywall screws . I bought a 5.5' piece of used pipe for the test rig. I can get 21' sections from the same place for the real tower.

[jwxr7]

Here's an out of focus picture of the test rig I threw together a little bit ago.

As it sits, the blade tips reach just over 10 feet at the top. Once in the truck I'm going to have to watch out for low tree branches.

[Xringer]

So, how does this work?
Do you drive 20 MPH to see how much power a 20 MPH wind will make?
Or, do you just drive to the top of a nice hill and wait for the wind?