wrote in message
...

Probably would be a good idea to characterize it with a few experiments,
as:

give excitation a step change and observe the time response of the
generated
voltage.

Think the dynamics would change with load?



Would be a good move - what would be really nice is to
look at the short term changes with a storage scope.

Yup. That or a PC-based data-acq setup. I have a scope and a LabJack DAQ
but no synchronous motor. DATAQ offers a simple DAQ for $24.95.
http://www.dataq.com/products/startkit/di194rs.htm
It's kinda slow at 240 samples/sec. That might be fast enough, given the
large inductances and rotational inertias involved.

Not sure how the dynamics will change with load - hopefully
not a lot. There are so many second order effects!

One interesting one is the effect of hysteresis in the
soft iron field circuit of the exciter alternator - sort of
minor electronic backlash within the servo loop. However my
present feeling is that, whoever designed the existing
regulator loop will have already solved most of these
problems for us.

Solved them, or just ignored them. Many control systems just do the best
they can with the system at hand, warts 'n all. Consider, for example, an
automotive cruise control. They certainly aren't quick and they're not
always precise, but they usually work acceptably well.