Through-Hole Contactless Slipring System Based on Rotating Magnetic Field for Rotary Applications

Contactless slipring system based on inductive power transfer is a preferable alternative to mechanical slipring assemblies. They are designed to deliver required output power to a rotary shaft without direct electrical contacts. The current single or multiple-unit through-hole single-phase systems often have limited power transfer capability within a confined physical space; thus, they may not be able to meet the load requirement for certain applications such as wind power pitch control. This paper presents an integrated polyphase through-hole contactless slipring system by generating a rotating primary magnetic field coupled with balanced power pickups at the secondary side with zero mechanical driving torque on the shaft. A new index termed "mutual inductance per pole" is introduced to simplify the analysis of the mutually coupled polyphase system to a single-phase basis. Simulation and practical experiments have demonstrated that, with the same physical size, the proposed contactless slipring setup can transfer 55% more power compared with the existing single-phase counterpart.