New approaches for contactless power transmission systems integrated in PM motor drives transferring electrical energy to rotating loads

Two concepts for drive-integrated contactless energy transfer from the stator to the rotor of an electric motor are presented in this paper. Both drive systems offer the possibility of not only producing torque on the motor shaft, but also to power a rotating load. The power transfer is realized using the magnetic air gap fields. Problems inherent to contact-based methods (slip-rings and trailing cables), such as wear and limited mechanical angles, are resolved. The theoretical approach is explained for both methods. A comparison of the methods regarding the level of independence between torque generation and power transfer, efficiency and costs is made.