AC Resistance of Inductive Coupler with Pitch Coils for Contactless Power Transfer

In recent years, many results in the field of contactless power transfer by inductive coupling have been published. Practical applications start from very low delivered powers of a few mW in case of medical implants, up to powers of the order of kW in case of charging the electric vehicle (EV) batteries. The key element of the power transfer system is the inductive coupler made of two planar coils of certain (circular or rectangular) shape, located at variable distances from one another. In this paper there are analyzed the inductive couplers used at EV, for transferred powers of kW or tens of kW, with a view to increasing the power transfer efficiency. An efficient design of the inductive coupler may be done only by knowing its parameters in the frequency range in which the system operation is provided.