Efficiency improvement of domestic induction appliances using variable inductor-load distance

In this paper, a power control strategy focused on improving the efficiency of induction heating appliances is presented. This strategy uses the distance between the inductor and the load as a control parameter, which is combined with the switching frequency of the resonant inverter. Therefore, a study of the efficiency of the involved subsystems is carried out. From these analyses, the theoretical efficiency of the combined converter-inductor system is analyzed. In order to verify experimentally the proposed power control strategy, an experimental setup has been built in which both distance inductor-vessel and switching frequency can be varied. By using this setup, a mixed electric-calorimetric energy balance is performed with the objective of measuring the impact of the proposed strategy in the appliance efficiency. The calorimetric method shows that the efficiency tendency of the appliance follows the predictions of the theoretical analysis.