A finite element simulation of an alternator connected to a nonlinear external circuit

The authors consider a squirrel-cage alternator (with laminated rotor and stator), connected to an external circuit whose components may be resistances, inductances, diodes, and voltage or current generators. The rotation speed of the rotor being given, the electromagnetic behavior of the system is computed. The field approximation inside the alternator is achieved by the finite-element technique, and the relative rotor movement with respect to the stator is taken into account using a rotation line (or slipping line) located in the air-gap. The external circuit is implemented in the model via an admittance matrix and in this way an integro-differential equation for the vector potential only is obtained. Numerical results are compared with experimental measurements and found to be in good agreement with them