I will first say a little more about the coils:
so i made the coils by using 20 cables of gauge 24 with a length of 5,6 meters.
Per coils i have 33 turns and 9 coils in total.
When i was looking on the internet, i found that everybody used the star formation for the connection of the coils.
I was wondering why and did some research on the internet.
After a while i came across a site that gave plenty of information about 3-phase circuits. (http://www.windstuffnow.com/main/3_phase_basics)
On the site it says that:
- the star formation has at low rpms a higher voltage and a lower amperage
- the delta formation has at low rpms a lower voltage and a higher amperage
- the resistance of the delta is 1/3 of that of the star
so basically the main reason why people always use star formation is because of the higher voltage at low rpm,
but with the star formation you also lose a lot of energy at higher rpms (1/3 energy loss in comparison with delta, THAT'S A LOT)
So i was wondering if I could use the delta formation in my wind turbine and find a way to solve the low voltage problem.
After some research on the internet, i found that if you double the turns on a coil, the voltage also will multiply by 2.
So i came with an idea:
because my coils consist of 20 cables in parallel, i can divide them in 4 groups of 5 cables.
By doing this i can change the number of turns by connecting the groups with each other. (look at the cable connection diagram)
The only problem is that this will take a lot of time to make. And to automate the change of the turns you will have to set up a complex electronic control board (and I'm not good enough in electronics to do that :( )
An other way, that is easier to make, is to switch between star and delta formation. You can use the star formation at low rpms and the delta formation at high rpms. The only problem is that I again don't know how I should automate it. I could measure the voltage and let it switch when a certain voltage is reached. The voltage an amperage in star and delta have a √3 ratio.
Is this a good idea and can someone help me with this (the automation)?