How to make a wind generator yourself?

 

DIY construction of a wind generator is not as difficult as it seems at first glance. If the wind speed in your area is greater than at least 4 m / s and there is a well-blown space a short distance from your home, you can organize a wind power station for less than $ 100.

The windmill, which was made by the author of this article, of course, requires many improvements, and if you have more money than time, it is easier to buy a ready-made generator, their cost starts from about $ 500. But if you want to experiment - this article is for you.

Propeller

The propeller for this windmill will be three-bladed. Although a two-bladed propeller is easier to build, such a propeller has its drawbacks, for example, it does not start immediately. Another drawback is the fact that when changing the direction of the wind, the two-bladed propeller vibrates strongly when turning, which is bad for the propeller itself and for the support of the generator. I made my propeller from 1 x 4 spruce planks. In this case, it is ½ 3½ inches, i.e. approximately 2x9 cm).I tried to find three boards without knots that have good vertical fibers and have approximately the same density (this was determined by weight). Of course, you can use other types of wood, I just found at hand only spruce. The size of the boards was chosen so that the propeller was light enough to start quickly and not heavily load the supports. It took about 2 hours to cut the blades. Of course, if I spent more time, the propeller would come out better, the sizes were mainly determined intuitively (my drawing is shown in Figure 1). However, if you want to do everything according to the rules, the network has a lot of information on aerodynamics, wood carving, and even on the manufacture of propellers.

After checking the blades for the same size, I connected them in two bolts and checked whether the resulting design is well balanced. When all three blades became the same, I painted them and attached them to the hub, which I used as an old 8-inch gear. After that, I was able to push the whole structure onto the axis and try to twist, determining the degree of balance and sawing off the too heavy parts (of course, then they had to be painted again). In total, the process of building and balancing the propeller took about 4 hours.

It should be noted that the three blades after balancing turned out to be of different thicknesses, in some places they differed by 1/8 inch (~ 3 mm). To avoid this, it is recommended to choose a tree of the best species and pay more attention to the initial sawing. For cutting, I used mainly an electric planer. It is also worth noting that the blades are not twisted, that is, their angle of inclination relative to the axis is always constant. For a propeller of such a small size, this is quite normal.

Generator

As a generator for a windmill, I used a 2 hp induction motor, which I pulled out of an old Taiwanese milling machine. I took it apart and made notches in the anchor so that 8 neodymium magnets could be inserted in order to turn the asynchronous electric motor into a low-speed generator with permanent magnets. The magnets are rectangular in shape and curved so as to fit the anchors of most engines with power from 0.5 hp. and higher. The notches are so deep that the edge of the magnet inserted into them is flush with the surface of the anchor. Magnets are glued with epoxy glue. They are arranged in pairs of two magnets with the same polarity.

The connected generator delivers 12V at about 160 rpm. With a different connection method, the generator could reach its maximum load at 80 rpm, however, this could significantly limit the current strength. Of course, the resulting current is alternating, and we need a constant to charge the battery, so I used a 40-amp transformer.

Tower

A tower is perhaps the most important part of a windmill, and most often it is neglected. To place it, I cut down a large pine, and in the center of the remaining stump I made a notch. The mast is made of a pine shaft. I drilled the base so that it could spin in a stump. A piece of steel pipe was planted on top to hold and rotate the windmill. During the assembly, the mast was supported by a small pine tripod. Another larger tripod was used for lifting. The tower was supported by four wire extensions with a diameter of 1/8 "(~ 3 mm) from an aircraft cable with lanyards for adjustment.

Chassis and tail of a windmill

 

Now I have started with pieces of the steel 9.5 mm, to which the generator can be screwed. To do this, I welded a pipe that fit in size to the pipe at the end of the mast - the windmill will rotate on it. In this there are no current collectors; I just used enough cable so that it could make several revolutions before stopping. The generator power line is slightly longer than the cable so that the windmill could stop without pulling the power cord. The tail is fixed with an iron triangle of 4 yards (~ 4 meters) from the center of rotation. Now the Two 1.27 cm steel bars would like to use to better secure the tail. I slightly shifted the tail and the generator about the axis, this was done extremely intuitively in the hope that gusts of wind would not spin it too quickly.

Launch

The generator starts well only at high wind speeds. This problem can be eliminated by making the propeller larger, wider than the blades or even more blades. But after starting the generator, the blades spun well enough even at a very low speed. The wind in our area is gusty; the direction often changes, so it is difficult for me to connect the received electricity with the wind speed. The best result that I was able to measure was 25 A at a high wind speed, although usually on my 12-volt batteries you can get 5-15 A at a low speed. Perhaps it makes sense to build a regulator with a matching transformer or a linear flow amplifier, which will better cope with the load on the generator and provide a significantly greater current strength.