Might this be
I am powerful on one side,
A motor runs one way, clockwise or anti. LDRUL seems to suggest anti CW rotation
twice when I am infinite,
This is one im confused with slightly. Maybe two motors together as a perpetual motion machine?
while half of me negates,
Half of the poles are negative in a motor
my other inflates.
While the other half is positive, at any time. leading to its rotation. (magnet reference)
You could call me an A ray,
an array of magnetic dipoles
or maybe a sill ender,
cylindrical in shape
but never, ever shall you
call me a well rounded figure.
the voltage required is Ac,never a fixed round value (guessing this one)
I can fly, or I can spin,
Motors can make copters fly, or spin things
but never will I have a double end.
they have only one shaft
It still doesnt feel completely right. Id thought of
magnetic and electric dipoles
but those didnt fit well either