Modelling of nonlinear magnetic material using a complex effective reluctivity

The modelling of nonlinear hysteretic magnetic material in the computation of shielding problems with sinusoidal excitation at power frequency is investigated. A complex valued effective reluctivity model is chosen which allows a sinusoidal calculation in spite of the material's nonlinearity. The absolute value and the phase of the reluctivity are determined from the hysteresis curves of the material. The complex Newton-Raphson method is adapted to solve the equation system. The results obtained are compared with measurements and with calculation results using a real valued effective reluctivity.