Reluctance Circuit Analysis and Structure Optimization of Contactless Transformer

Contactless transformer is the key component in inductive power transfer (IPT) system and its coupling coefficient (k) will directly affect the power transfer efficiency. In this paper, a contactless transformer applied in movable vehicle with the structure that primary and secondary sides are asymmetrical is studied. By analyzing the magnetic flux distributions of the transformer, magnetic reluctance circuit of this contactless transformer is built, and the optimization based on the reluctance circuit was taken, and the finite element methods (FEM) calculation results confirmed the theory analysis. Furthermore, a 30 kW/30 kHz IPT system based on this novel structure is measured as 85.3% at 30 kW power transfer across an air gap of 48 mm.