Numerical analysis of transient field problems in electrical machines

A 2-dimensional section of a synchronous machine is modelled using 1st-order triangular finite elements. Equations are formulated by the use of Ampere's law. The transient performance of the machine is obtained by determination of the vector potential distribution at successive instants in time, the effect of closed circuits being taken into account in the formulation of the equations by the introduction of conductivity matrices. Variable permeability of steel and the effect of eddy currents are taken into account. The method is applied to calculate the performance during a field-decrement test.