Contactless Rotor Excitation for Traction Motors

This paper proposes a new rotary transformer topology enabling significant reduction of leakage inductances, improvement of coupling factor and significant improvement of power transfer capability compared to traditional topologies thanks to its interleaved windings and resonant compensation circuits. The proposed rotary transformer features a non-ferrite rotating part made of lightweight strong non-conductive and non-magnetic composite material and a large airgap, allowing safe operation at high rotational speeds. Hence, this novel rotary transformer can enable the adoption of wound rotor synchronous machines for electric or hybrid vehicle traction. The performance of the proposed new topology was evaluated and compared to the conventional one. Significant performance improvement was confirmed.