The model has 3 parameters that can be tweaked... the scaling factor for the open circuit voltage, the inductance, and the series resistance. The values that I ended up with for each parameter were adjusted to provide a reasonably good match between the V-I (voltage-current) curves for the model and the test data for the range of speeds and loads that were of interest to me.
The model does have a value of 2.8 ohms for the series resistance, while the winding itself measures 2 ohms (IIRC). Close enough for gov't work?
The fact that the model and the data match pretty well shows that the resistive portion of the dynamo impedance is much smaller than the inductive portion over typical operating speeds.
As far as design choices for a dynamo... that's beyond my expertise! I had a nice class on electric machinery back in my undergrad days, and it was pretty interesting. Never had a chance or reason to get any further experience, beyond some details on sources of losses in the magnetics in a switching power supply. Well, I've spent some time on EMC, where the goal was to add losses at specific frequency bands through the use of ferrites. That doesn't seem to be too relevant to bike dynamos, though.
correct.. that was for the unloaded dynamo.
I think I've heard a similar comment regarding the reason for the shape of the waveform, but that's beyond my knowledge of magnetics.
It does serve as a cautionary tale to people who want to design circuits for dynamo lights and assume that the voltage will always be a sine wave.
my guess is that series will probably yield better results, but that does depend on the design of the light. Not sure that I can imagine a light that would actually produce more light when wired in parallel, but I'm not ruling out the possibility.
Steve in Peoria