A unified time domain surface impedance concept for both linear and non-linear skin effect problems

A new time-domain boundary element technique for calculation of the magneti c field and temperature distribution in the skin layer of conductors of iso tropic material with general BH-curve and sigma(T) relationship is proposed . The formulation consists of the surface integral equation for the scalar magnetic potential, and the time-domain surface impedance boundary conditio n (SIBC) for the normal component of the magnetic field. The SIBC is obtain ed in the form of 1-D non-linear diffusion equations for the magnetic field and temperature inside the conductor normal to its surface. The number of integral equations is the same for 2-D and 3-D problems. The technique requ ires the same computational expenses as solving the problem in well-known p erfect electrical conductor limit. The numerical examples are considered.