Method for controlling the inductive charging of a user device and associated charging device for motor vehicle

1. A method for controlling the inductive charging of a portable item of user equipment by a charging device, said charging device comprising a reception surface able to receive the item of user equipment, emitter coils and a magnetic field guide able to direct a magnetic field in a plane parallel to the reception surface, the charging device is equipped in a preliminary step with at least two magnetic antennas, each designed to emit a magnetic field and each designed to partially receive the magnetic field emitted by the other antenna, the method comprising:

a) Simultaneous emission by the two antennas, having a first phase shift at input with respect to one another;

b) Measurement of at least one parameter at the output of the antennas;

c) Storage of the measured parameter;

d) Comparison between the at least one parameter thus measured and a predetermined value;

e) Repetition of the preceding steps for other phase shift values; and

f) Controlling of the charging based on the comparison results.

2. The inductive charging control method as claimed in claim 1 , wherein the measured parameters consist of a voltage and/or a phase between the current and the voltage that are measured at the output of each antenna.

3. The inductive charging control method as claimed in claim 2 , wherein the predetermined value comprises parameters measured without a metallic object on the reception surface.

4. The inductive charging control method as claimed in claim 1 , wherein the predetermined value comprises parameters measured for a plurality of locations of metallic objects on the reception surface.

5. The inductive charging control method as claimed in claim 1 , wherein the predetermined value furthermore comprises parameters measured for a plurality of types of metallic object.

6. The inductive charging control method as claimed in claim 1 , wherein the predetermined value consists of parameters measured at a previous time, for one and the same phase shift value.

7. A device for the inductive charging of a portable item of user equipment, intended to be housed on board a motor vehicle, comprising:

a reception surface able to receive the item of user equipment;

emitter coils;

a magnetic field guide able to direct a magnetic field in a plane parallel to the reception surface;

At least two magnetic antennas, each designed to emit a magnetic field and each designed to partially receive the magnetic field emitted by the other antenna;

emission means electrically connected to the two antennas, comprising phase shift means for a phase shift between the antennas; and

reception and processing means comprising:

i) measuring means for measuring at least one parameter at the output of the antennas,

ii) storage means for storing the measured parameter,

iii) comparison means for comparing between the at least one parameter thus measured and a predetermined value,

iv) detection means for detecting an object, for locating said object and type of object on the reception surface on the basis of the result of the comparison,

v) control means for controlling the charging on the basis of the detection performed.

8. The charging device as claimed in claim 7 , wherein the measuring means for measuring parameters consist of measuring means for measuring a voltage and/or measuring means for measuring a phase at the output of the antennas.

9. The charging device as claimed in claim 7 , wherein the magnetic field guide consists of a ferrite.

10. The charging device as claimed in claim 9 , wherein the antennas are in the form of loops wound around the ferrite.

11. The charging device as claimed in claim 7 , wherein the antennas are in the form of planar windings located in a plane parallel to the reception surface.

12. The charging device as claimed in claim 7 , wherein an emission frequency of the two magnetic antennas is between 20 KHz and 20 MHz.

13. The charging device as claimed in claim 7 , wherein the antennas are near-field communication radiofrequency antennas.

14. The charging device as claimed in claim 7 , wherein the antennas are inductive charging antennas.

15. A motor vehicle, comprising a charging device as claimed in claim 7 .

16. The inductive charging control method as claimed in claim 2 , wherein the predetermined value consists of parameters measured at a previous time, for one and the same phase shift value.

17. The charging device as claimed in claim 8 , wherein the magnetic field guide consists of a ferrite.