Nonlinear time-domain formulation of the method of moments

In this paper a time domain formulation of the method of moments for the analysis of nonlinear materials is presented. The magnetization vector M and the nonlinear constitutive equation H=H(B) are used in order to express the magnetic vector potential as a function of conduction currents only. The Lorentz gauge is used in order to express the scalar potential as a function of the vector potential. By combining the electric field definition and Ohm's law an integral equation in the conduction current unknowns is obtained. The method of moments is then applied to this equation. The use of pulse functions as subsection bases allows a quick matrix set up especially when regular volume shapes are selected. Calculated results are compared with results obtained with other methods relating to benchmark problems.