This is something I've been scratching my head over for a couple of days...

I want to model a permanant-magnet type (bicycle) AC generator, to calculate its output at a given speed / load. Characteristics of the actual device can be seen here:

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(the plots are no-load and two different load values)

I know that the generator has a finite current limit, due to the induced current generating its own magnetic field (someone correct me if I'm wrong), and I can ***see*** what is occurring, but I just can't seem to define it mathmatically :o(

I need to calculate Vout as a function of rotational speed and load.

This is frustrating because it's pretty basic, but hopefully is one of those cases of just getting past the starting post. Before anyone asks, no this is not a homework project (FAR to many years since I was at college) nor anything further than hobbyist tinkering.

Thanks, Nick