Gary sez:

" Note also that it isn't mandatory to follow his limits of same RPM
or same current either. Those were just his arbitrary choices.
Increasing either speed (voltage) or torque (current) will allow
greater input power, and greater output power, up to the thermal
limits of the motor/generator."

I thought Jim Pentagrid covered that very well myself. His choices were
made in accordance with preserving the parameters addressed in the original
question. As Jim Rozen stated, boundary conditions were specified at the
outset.

Bob Swinney