Serpentine Coil Calcs

A description of the method I used to estimate the number of turns required for the serpentine coil based on the results from the test coil.

Category:

Science & Technology

Tags:

• VAWT
• vertical
• axis
• wind
• turbine
• serpentine
• coil
• generator
• calculations

[davevanden1]

hi cale where did you get this program from ?

I want to rewind mine and try to get 24 volts at 100 rpm

[Caleb6543]

@davevanden1 I just made an excel spreadsheet, but Open Office software would work too.

[Caleb6543]

@davevanden1 I'll try to get a link to the spreadsheet on my web site today.

[sjh7132]

It will be interesting to see how close you get. I think your magic number is really a combination of 1/2 to convert peak to peak to just peak voltage and sqrt(3) or 1.732 to get peak 3 phase in star configuration. 1.2 * 1.732 = .866. Yours might be more accurate because you also worked in the odd waveform.

Will your final stator be pretty much solid wire?

[Caleb6543]

@sjh7132 I'm planning on using a single strand of 22GA magnet wire. I just bought some wood and dowels to wind the coils and I have a drawing for the holes to fixture the coils. So hopefully I can get the stator made within the next week or two.

I think you're right about the sqrt(3) thing. I had wondered where that number came from - thus the little waveform study.

[Zypkin]

@Zypkin ...to avoid that you should account for the resistance introduced by the additional turns and consider what is the maximum current you want to drain...

...but I guess U know that already :)

[Zypkin]

in Ur math you did not consider the voltage drop due to the internal impedance of the generator when you have a load. Therefore you will get your voltage right only at open circuit but it will drop down unpredictably as soon as you connect the load :(

[Zypkin]

@sjh7132 ...ehmmm.... I dont think so :)

..or maybe I just dont get what U wrote.

What I wanted to say it is that he used the formula to convert 3phase voltage into DC voltage (which if you reduce it to numbers is 0.827) and there is no wondering abt that.

Then I added that maybe he had in mind the peak voltage of a single phase... but if you wire the 3 phases in star configuration that 0.827 becomes actually a 1.43...

...then wiring star he would have been fine with 28 turns instead 48 :)

[sjh7132]

@Zypkin

Isn't that what I said? :-)

[Zypkin]

@sjh7132 ...the magic number is actually no magic and comes from the conversion from 3phase to DC ---> Vdc = 3*3^0.5/pi()*(Vpp/2)

Nevertheless this is true on any Vpp ...so if U wire you generator in triangle configuration Ur Vpp is actually the Vpp of each coil... but if U wire it in star U get a bonus of 1.73 times... meaning you can have use less turns.

@ Claeb6543: what do U think abt it? I believe U made calcs for a triangle config...