CONTROLLING WIRELESS TRANSMISSION OF ENERGY TO A MEDICAL DEVICE

A system for suppling energy to a medical implant is provided. The system comprising an electrically powered medical device adapted to be implanted in a patient, the medical device comprising an internal energy receiver adapted to power the medical device and having a secondary coil for wirelessly receiving energy and an external energy source adapted to be located externally to the patient and having a primary coil, and adapted to wirelessly supply energy to the internal energy receiver using the primary coil. The system is arranged to determine a coupling factor between the primary and the secondary coil, the external energy source is adapted to transmit a first amount of energy to the energy receiver for enabling the medical device to detect information related to the coupling factor, and the internal energy receiver comprises an electronic component connected to the secondary coil for preventing or substantially reducing the flow of electrical current between the secondary coil and the medical implant during the measurements of parameters related to the coupling factor, and wherein the medical device is configured to determine the coupling factor. The system is further arranged to use the coupling factor as feedback information during energy transfer.