Ali Abdolkhani - Department of Electrical and Computer Engineering, University of Auckland Auckland-New Zealand
Aiguo Patrick Hu

This paper proposes a sandwiched winding structure used for contactless slipring systems. A contactless slipring is an alternative to current mechanical slipring systems. To minimize the losses and increase the power transfer capability, a new magnetic coupling structure with unique core geometry is proposed to transfer electrical power across an air gap allowing for free rotation. A Finite-Element-Boundary-Element (FEM-BEM) model is developed and FEM analysis conducted. The proposed contactless slipring system has been verified using simulation results. The rotating transformer output power, voltage gain and current gain plots are presented to assess the system performance. It has been found that the fringing flux on the windings, affects the conduction losses and the EMI, which can be reduced by placing the winding away from the air gap of the core. Practical design considerations as well as advantages of the proposed structure as compared to a typical coaxial design of rotating transformer have been discussed. It has been shown that the proposed coupling structure can deliver up to 4173 Watts of power at a 25 Ω resistive load. An excellent magnetic coupling factor of 0.92 is achieved as a result of the specific core geometry with a single air gap. The voltage gain for this system is 0.94, which indicates that the voltage drop across the leakage inductances and windings resistances is insignificant

Contactless Power Transfer (CPT), Fringing flux, JMAG, Rotating Transformer