Analysis of an induction heating system by the finite element method combined with a boundary integral equation

The method, based upon the finite element technique, is presented for the analysis of an induction heating system in unbounded free space. In the induction system, a quasistatic magnetic field problem with cylindrical symmetry is solved. First, a mathematical boundary is defined arbitrarily in free space to contain an induction system inside. An integral relation is derived on the boundary surface using the response function excited by a circular line current. The boundary relation gives a constraint to the finite element analysis in the interior region. In the finite element discretization, first-order elements are used, and constant elements are assumed for the discretization of the boundary equation. To couple the finite element analysis to the boundary integral equation, only the potentials differently approximated on the boundary are matched reasonably. After the accuracy of the method is verified for a single coil, load characteristics of a practical induction heating system are analyzed.