Analysis and Optimization of the Efficiency of Induction Heating Applications With Litz-Wire Planar and Solenoidal Coils

Optimization of the efficiency of an induction heating application is essential in order to improve both reliability and performance. For this purpose, multistranded cables with litz structure are often used in induction heating applications. This paper presents an analysis and optimization of the efficiency of induction heating systems focusing on the optimal copper volume of the winding with respect to different constraints. The analysis is based on the concept of a one-strand one-turn coil, which captures the dissipative effects of an induction heating system and reduces the number of variables of the analysis. An expression for the efficiency of the induction heating system is derived. It is found that, with the geometry and the other parameters of the system fixed, efficiency depends on the copper volume of the windings. In order to use this result to optimize the efficiency of an application, volume restrictions, the packing factor and the window utilization factor are also considered. The optimum frequency for an induction heating system is also studied in this study. An experimental verification for both planar and solenoidal cases is also presented.