Fixed vibrations

I've shortened the distance between where the blades connect to the main shaft. I've also put bolts in to permanently hold the pipes and blades at the correct angles. That seems to have solved the vibrations as high wind speeds. The RPM is also higher at high wind speeds, thus capturing more energy.

As soon as we get our new asphalt roof put on our home, I'll attempt to put the VAWT up on top of the roof where it can get higher average wind velocity. I'm also planning to put some solar panels up there.

better connection

I've made a better connection between the windmill and the generator.
It works much better.

We had some >20 mph winds today and I had to stop the windmill due to vibrations.
I need to figure out some strategy for reducing the vibrations at high wind speed.
That is the fun of this project - there is always something new to improve upon or invent.

Conneced up the generator

I've connected a steel cable between the generator and the windmill.
You can see a movie of this at http://www.youtube.com/watch?v=Pjai2SFBu-c&feature=channel

I've modified the central post of the VAWT to make it less susceptible to vibrations. The center steel pole now has a 1 inch diameter rather than 3/4 inch diameter.
Watch the video at http://www.youtube.com/watch?v=7jj7lEQg6As

More Efficient VAWT

This new design is awesome!

Lower cost, more efficient, and easy to build

Modified windmill hub

I've modified the hub of my VAWT to improve the rotation Here is a video

Latest Plan for 2 Phase design

This is what the waveforms look like for the proposed two phase design. The goal is to have 18 volts peak to peak at less than 60 rpm and get as high a power output as possible.

The Circuit Schematic looks like this

The new plan is to have 18 coils; nine for each phase.

Wire tests

The 24 AWG wire seems to be a waste of time for these generators. It has too high of resistance and even though the voltage is very high, the power is so low that it doesn't compensate. So now I am trying some 15 AWG wire that I got for a low price on ebay. It seems to work well as long as I have large coils. I can get about 2 volts per coil at 60 rpm and if I have 9 coils per phase then that is 18 volts peak to peak per phase. Here is a scope picture of voltage versus time for two coils at 42 rpm.

First experiment

The first of three phases (for the three phase design) was wired up and it was found that at 60 rpm the peak to peak voltage for one phase was only 2 volts. This tells me that I don't have enough coils of wire per phase. I would like to have a peak to peak voltage of about 40 volts at 60 rpm, so I am off by a factor of 20! So what do I do? I only have 5 coils per phase. If I go to a 2 phase design I can fit 12 coils of wire around the wheel per phase. I then need to increase the number of turns per coil by a factor of 8.5. I used AUG14 wire for the three phase experiment, which is very fat wire. If I use AUG24 wire I may be able to achieve the high voltage at the low rpm. The picture below illustrates how the coils could be positioned for the 2 phase design.

RPM and Hertz

There are 36 spokes in the wheel and 36 magnets. As the magnets pass the coils of wire they will produce a sinusoidal wave of induced current. If the wheel revolves once every second then there will be 18 cycles of induced current in the wires. The frequency of induced current would then be 18 Hertz. The voltage will depend on the number of turns in the wire, the velocity of the magnets relative to the coils and the efficiency of the inductive coupling. There are three phases each offset by 1/3 of a cycle. Here is a circuit model for this kind of generator charging a 12 volt battery.

Position of the coils around the wheel

This is one example of how the wire coils can be placed relative to the magnets to create three phases.

The voltage will depend on the number of turns in the coils and the rpm of the wheel.

Bicycle Wheel Generator for the VAWT

This bicycle wheel has 36 magnets fastened to the rim that correspond to the 36 spokes. The wire coils will be positioned around the edge to create a three phase PMA.

New three bladed VAWT