Doubly-fed machine with wireless power transfer ability

In this paper, a current injection method is proposed which enables wireless power transfer in a doubly-fed machine. In the proposed method, currents of the same frequency are injected to both stator current and mover current. The magnitude of the stator side injected current is kept constant during the operation. The mover side injection current is controlled to be in phase with the induced voltage, and the magnitude of the current is used for controlling the voltage of the floating capacitor on the mover. Injection frequency is set higher than the original operation of the machine so that there would be minimal effect on the operation. The proposed method was verified with a simulation, and a position control experiment was performed with an implemented dual-active magnetic bearing system.