Improved modeling of the nonlinear B-H curve and its application in power cable analysis

An improved model of the nonlinear B-H curve of ferromagnetic material is introduced. The B-H curve is represented by a Fourier series, based on a set of measurement data. With the Fourier series expression, the magnetic energy density can be calculated and then used in an iterative procedure for determining the permeability everywhere within the ferromagnetic material. To validate the model's accuracy, it is employed, together with the finite-element method, to investigate the zero-sequence impedance of an underground pipe-type cable and the magnetic field in its vicinity. The computational results are compared with the measurement data, and a good agreement is observed.