Apparatus and method for wirelessly transmitting energy

1. Method for wirelessly transmitting energy from a primary device to an implantable secondary device, wherein the primary device comprises a primary coil and the secondary device comprises a secondary coil for electromagnetic interaction with the primary coil, with a control process which comprises:

(a) measuring a primary current flowing through the primary coil and a primary voltage applied to the primary coil,

(b) calculating a secondary current of the secondary coil and a secondary voltage of the secondary coil on the basis of the measured primary current and the measured primary voltage,

(c) comparing the calculated secondary current with a desired secondary current and/or the calculated secondary voltage with a desired secondary voltage,

(d) predefining a desired primary current and a desired primary voltage on the basis of the comparison, and

(e) operating the primary coil with the desired primary voltage and the desired primary current in order to transmit energy to the secondary coil.

2. Method according to claim 1 , including determination of a mutual inductance of the primary coil with respect to the secondary coil on the basis of a predefined primary current through the primary coil and a primary voltage applied to the primary coil, the transfer function being used to calculate the calculated secondary current and/or the calculated secondary voltage of the secondary coil.

3. Method according to claim 1 , including determination of a transfer function on the basis of the mutual inductance, the mutual inductance being used to calculate the calculated secondary current and/or the calculated secondary voltage of the secondary coil.

4. Method according to claim 3 , including determining the transfer function and the mutual inductance independently of real-time feedback of a secondary current measured value and independently of real-time feedback of a secondary voltage measured value.

5. Method according to claim 1 , including carrying out the control process independently of real-time feedback of a secondary current measured value and independently of real-time feedback of a secondary voltage measured value.

6. Method according to claim 1 , including transmitting information relating to a power required by the secondary device from the secondary device to the primary device.

7. Method according to claim 1 , including transmitting information relating to a transmitted power and/or a load from the secondary device to the primary device.

8. Method according to claim 7 , including monitoring by the secondary device of the transmitted power and, in the event of a change in the transmitted power, transmitting an item of information relating to the change in the transmitted power.

9. Method according to claim 1 , wherein the comparison of the calculated secondary current with the desired secondary current and/or the calculated secondary voltage with the desired secondary voltage respectively being used as an input signal for a PI controller in order to determine the desired primary current and/or the desired primary voltage.

10. Method according to claim 1 , including controlling the primary coil with a pulse-width modulation method.

11. Apparatus for wirelessly transmitting energy, comprising:

(a) a primary device which has a primary coil,

(b) a secondary device which comprises a secondary coil which can be arranged for electromagnetic interaction with the primary coil, and

(c) a checking unit which is set up to carry out a method according to claim 1 .