Principle of a multi-load/single converter system for low power induction heating

The induction heating appliances used for cooking generally include two or four inductors and in the most common solution, a converter is connected to each inductor. The main aim of this paper is to suggest a way of building a multi-load/single converter system, based on the use of a series-resonant ZVS inverter supplying several resonant loads. The principle can be probably extended to different applications (DC-to-DC converters, high power induction heating applications) but their study has been restricted to a low power induction heating context. In order to make this study, suitable models for the loaded inductors had to be found. Therefore, in the first part of this document, a number of different electrical inductor models, from the basic L-R equivalent circuit to a representation taking into account eddy currents effects, are presented. The second part describes the multi-load operating principle with respecting ZVS conditions, by the analysis of an R-L inductor model. Finally, the third part completes this work with simulations, including a more realistic model of the inductors and the associated experimental validation. These emphasize the interest of this original system that is currently being evaluated for an industrial application.