Alternator Calculator

Winding the coils and making the stator

Alternator Calculator

Postby Stefan on Mon Aug 18, 2008 2:26 pm

I just found this calculator on a website and was wondering if anyone wanted to comment

Are the values asked for relatively easy to come by and/or measure?

I am assuming the number of poles is the number of magnets (or double the number as there is a N and a S pole? What would this be with 2 magnet rotors on either side of the stator).
What is the magnetic flux density and is it easy to obtain for the magnets being used here?
The line resistance, I guess is the resistance of the copper wire used for the coils. I am not sure what unit this is supposed to be in (ohms I guess) or how to measure it (multimeter should do this).

What you think?
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Re: Alternator Calculator

Postby windgat on Mon Aug 18, 2008 8:55 pm

It looks great... but... how to arrive at the flux density?? One way to do it is to make a first model, measure the open circuit voltage for a given RPM, then adjust the calculation until the graph matches the actual voltage reading. I did this and get a flux density around 0.3 for N35 46x30x10mm magnets, spacing about 10mm.

I am not sure how the calculator deals with phases - I use 3 phase, so maybe I should divide the number of coils by 3...

I am also unsure what 'line resistance' is - resistance of one phase? All phases added?

Finally the 'rotor power' ends up far lower than the alternator power - doesn't seem right!

Did you see Greystokes posts? He seemed to be able to do some pretty good calculations about flux density - maybe he could offer some helpful comments.
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