Inductive power transfer system with a rotary transformer for contactless energy transfer on rotating applications

This paper examines an inductive power transfer (IPT) system with a rotary transformer as an alternative solution to slip ring systems for a contactless energy transfer to rotating equipment. A prototype system is set up, consisting of a rotating ball bearing shaft and an exemplary sensor circuit mounted on the shaft. Three possible transformer configurations are analyzed theoretically and experimentally regarding the self-inductance, the coupling factor and the losses in the litz wire. To utilize the intrinsic stray inductances of the rotary transformer, a series compensated resonant converter is implemented for the prototype system.