Fig. 1 shows a rotating VR motor @6#. It mainly
consists of a rotor, a stator winding, and an iron
core to link up the magnetic circuit. When a current
is passes through the stator winding, then
magnetic flux links through the iron core and
eventually the rotor will be attracted into the alignment
with the pole pieces. On the contrary, if an
external restraining torque is applied to the rotor
and displaced from the aligned position, the rotor
will stay in an equilibrium position where the rotor
alignment torque balances out the external restraining
torque.