Device for inductive transmission of electrical energy
A device for inductive transfer of electric energy from a stationary unit including at least one primary inductance to a vehicle that is adjacent to the unit and has at least one secondary inductance. The stationary unit has a device for detecting the presence of an electrically conductive object in a predetermined area that borders the primary inductance. The area can be between the primary and secondary inductance during the inductive energy transfer. The device has at least one measuring inductance, a measuring unit for measuring the impedance of the measuring inductance and an evaluation unit connected to the measuring unit. Preferably, the device is equipped with a plurality of measuring inductances which form a regular two-dimensional arrangement extending approximately in one plane, the plane lying perpendicular to the main direction of the magnetic field that is generated by the primary inductance during operation.
1. A device for inductive transmission of electrical energy from a stationary unit having at least one primary inductor to a vehicle in a vicinity thereof having at least one secondary inductor, the stationary unit comprising a control unit for controlling a current supply to the primary inductor, the device comprising:
a plurality of measuring inductors positioned in at least one plane lying perpendicular to a main direction of a magnetic field produced by the primary inductor during transmission of electrical energy;
at least one measuring device operatively-connected with the plurality of measuring inductors to measure a plurality of impedance values corresponding to different physical locations of the plurality of measuring inductors; and
an evaluating device operatively-connected to the at least one measuring device, the evaluating device configured for
comparing the measured impedance values with stored impedance values to determine a physical location of measuring inductors having impedance values which are different than the stored impedance values,
detecting the presence of an undesired electrically-conducting object and a location of the undesired electrically-conducting object using the determined physical locations when the undesired electrically-conducting object partially covers the primary inductor,
detecting the presence of the vehicle using the determined locations and the impedance values when the secondary inductor is positioned proximate the primary inductor, and
causing the control unit to deactivate the current supply in the presence of the undesired electrically-conducting object.
2. The device according to claim 1 , wherein the plurality of measuring inductors are planar coils.
3. The device according to claim 1 , wherein the plurality of measuring inductors are arranged in a form of a grid pattern.
4. The device according to claim 1 , wherein the plurality of measuring inductors are arranged in successive rows each offset in their longitudinal direction by half a grid spacing of a row.
5. The device according to claim 1 , wherein the plurality of measuring inductors are connected together in groups such that each of the plurality of impedances corresponds to a group.
6. The device according to claim 5 , wherein each group of measuring inductors is operatively-connected to a unique measuring device.
7. The device according to claim 1 , wherein each of the plurality of measuring inductors is operatively-connected to a unique measuring device.
8. The device according to claim 1 , wherein the plurality of measuring inductors are connected through a multiplexer connected to a common impedance measuring device.
9. The device according to claim 1 , further comprising an indicating device connected to the evaluating device, the indicating device generating a warning signal in the presence of the undesired electrically-conducting object.
10. A safety device for use in a system of inductive transmission of electrical energy from a stationary unit having at least one primary inductor to a vehicle having at least one secondary inductor, the device comprising:
a plurality of measuring inductors positioned in at least one plane lying perpendicular to a main direction of a magnetic field produced by the primary inductor during transmission of electrical energy;
at least one measuring device operatively-connected with the plurality of measuring inductors to measure a plurality of impedance values corresponding to different physical locations of the plurality of measuring inductors; and
an evaluating device operatively-connected to the at least one measuring device, the evaluating device configured for
comparing the measured impedance values with stored impedance values to determine a physical location of measuring inductors having impedance values which are different than the stored impedance values,
detecting the presence of an undesired electrically-conducting object and a location of the undesired electrically-conducting object using the determined physical locations and the impedance values when the undesired electrically-conducting object partially covers the primary inductor,
detecting the presence of the vehicle using the determined locations and the impedance values when the secondary inductor is positioned proximate the primary inductor, and
causing the control unit to deactivate the current supply in the presence of the undesired electrically-conducting object.
11. The device of claim 10 , wherein the plurality of measuring inductors are coils.
12. The device of claim 10 , wherein the plurality of measuring inductors are distributed upon a surface of a housing containing the primary inductor.
13. The device of claim 10 , wherein the plurality of measuring inductors are connected together in groups wherein each of the plurality of impedances corresponds to a group.
14. The device of claim 10 , wherein the plurality of measuring inductors are connected through a multiplexer connected to an impedance measuring device.
15. The device of claim 10 , wherein the undesired electrically-conducting object is at least one of refuse, debris, and an article of sabotage.
16. The device of claim 10 , wherein the plurality of measuring inductors are arranged in a form of a grid pattern.
17. A method of improving safety in the use of a system of inductive transmission of electrical energy from a stationary unit having at least one primary inductor to a vehicle having at least one secondary inductor, the method comprising:
positioning a plurality of measuring inductors in at least one plane lying perpendicular to a main direction of a magnetic field produced by the primary inductor during transmission of electrical energy;
operatively-connecting at least one measuring device with the plurality of measuring inductors to measure a plurality of impedance values corresponding to different physical locations of the plurality of measuring inductors; and
operatively-connecting an evaluating device to the at least one measuring device and the evaluating device
comparing the measured impedance values with stored impedance values to determine a physical location of measuring inductors having impedance values which are different than the stored impedance values,
detecting the presence of an undesired electrically-conducting object and a location of the undesired electrically-conducting object using the determined physical locations when the undesired electrically-conducting object partially covers the primary inductor,
detecting the presence of the vehicle using the determined locations and the impedance values when the secondary inductor is positioned proximate the primary inductor, and
causing the control unit to deactivate the current supply in the presence of the undesired electrically-conducting object.
18. The method of claim 17 , wherein the plurality of measuring inductors are distributed upon a surface of a housing containing the primary inductor.
19. The method of claim 17 , wherein the undesired electrically-conducting object is at least one of refuse, debris, and an article of sabotage.