Magnetic Fields in Nonlinear Salient Pole Alternators

The flux densities under load are established in the cross section of salient pole alternators of low pole numbers. The two-dimensional partial differential equations describing the magnetic vector potentials are first transformed in partial difference equations and a new algorithm is given. A combination of rectangular and polar grids is used to follow the contours of the alternator. The reluctivity of the material is assumed to be the function of the magnetic induction. An iteration procedure consisting of relaxation of the vector potentials using a new form of blockrelaxation and underrelaxation of reluctivities is described. A computer program in FORTRAN language is given and applied to find the airgap radial inductions for a 2750-kVA, 2300-volt, 60-Hz, three-phase, eight-pole alternator.