ABSTRACT
Any electrical motor is a power transformer that converts electrical energy in mechanical one. When it is in action it works under the principle of interaction of currents and magnetic fields, which leads to a general analytical description of the processes occurring in any motor, including the present work. Because of the complexity of the electromagnetic and electromechanical processes happening in the real electric machine, its full mathematical description is impractical, and from the control viewpoint it is ineffective due to the “Dimension Curse’’, well known in classical control. It is sufficient to use the classical mathematical models that consider the basic physical features of the processes happening inside the motor for control design (Leonhard, 2001), (Boldea & Nasar, 2005). These mathematical descriptions are based on the following standard assumptions:
– The magnetomotive forces created by phase currents have sinusoidal distribution along an air gap, i.e. influence of the higher frequency harmonics of a magnetic field is not considered;
– Symmetry of the electrical machine; – Influence of grooves is not considered, but the machine can be salient-pole; – Absence of saturation and losses in steel; – The energy of any electrostatic field is not considered; – Processes are concentrated.
