Normal-Mode Decomposition of Surface Power Distribution in Multiple-Coil Induction Heating Systems

We present a procedure to obtain the surface power distribution in the load of a multiple-coil induction heating system. The surface power distribution is modulated by applying certain phase shifts between the currents flowing through the coils. This modulation depends on the coupling factors between the coils. In this paper, the surface power distribution is obtained using the tangential electrical field distribution arising from each coil in the surface of the load normalized by the current flowing through the coil. For the sake of simplicity, the reference system to be analyzed consists of two concentric coils. Finally, the model is validated, giving the comparison between the simulation results and the experimental data of the dependence on the modulation parameters, i.e., the phase-shift between the coils, of the total power delivered to the load.