Solution of magnetic fields and electrical circuits combined problems

A finite element formulation is developed to analyse the magnetic fields in constrained electrical circuits by combining field and circuit equations. The terminal voltages are specified and the corresponding magnetizing currents assumed as unknown. This method takes into account the eddy currents and it has a symmetric coefficient matrix with respect to the ones mentioned in the literature. This approach makes it possible the computation of the characteristics of induction motor, specially squirrel cage induction motor, excited by constant voltage power sources. It is verified using a magnetic relay and a 4-pole shaded-pole motor.