High-efficiency arrays of inductive coils

Abstract

Inductive heating is widely exploited in industrial operations including metal hardening, forging and brazing. Recently, as a promising alternative to traditional heating, inductive heating has attracted substantial commercial interest for domestic cookers. This is because inductive heating o ers fast, precise and e cient heating compared to traditional methods that make use of either convection or conduction as a means of heat transfer. To introduce full exibility in using the cooking space, a strong demand is currently directed toward all-surface induction ovens, with the capability to heat a vessel placed arbitrarily anywhere on the surface of the induction cook top. For this purpose, inductive coils of tens of mm in diameter are required to be designed and stacked together to form coil arrays. However, this typically comes at the cost of reduced e ciency. To address this problem, this thesis work focuses on high-e ciency coil arrays designed for all-surface induction with optimum ferrite placement. Here analytical, numerical and experimental electromagnetic analyses of sample coils are performed. Effects of di erent ferrite placements are investigated and, contrary to the general intuition of placing ferrite bars only under the coil, an e ective way of ferrite placement is proposed and shown. These results indicate that the proposed highe ciency arrays of inductive coils are highly promising for all-surface inductive heating.