Control system for contactless electrical energy transfer with varying air gap

Inductive power transfer (IPT) is a system by which electrical energy may be transmitted without electrical connection through a large air gap between coils. Systems usually considered in the literature are the ones with a constant air gap. The paper describes the analysis of IPT, which allows for supplying an electrical load in the conditions of slow, in relation to the dynamics of power supply, changes in the dimensions of the air gap. The system has been proposed which controls the frequency of inverter output voltage in order to maintain resonance for actual air gap dimensions. The IPT control system stability for a selected structure has also been determined. Theoretical developments are compared with experimental results on the prototype IPT.