Basic Principle for Electric Motor

The Electric Motor operation is based on the following points:

 •At least one of the two magnetic field is generated by a solenoid carrying a current.
 •The phase relation between the rotor and stator magnetic field (i.e. the load angle) must be always greater than 0°in  order to keep the motor in motion (negative angles reverse the rotation).
 •Output torque depends on both the solenoid current and load angle.

 •Motor rotation causes a back electro-motive force opposing the motion itself.

The magnetic field intensity is proportional to the current forced into the motor leads.
•The magnetic field rotation is automatically obtained commutating the active coil through mechanical switches (brushes).