Inductive charging system with charging electronics physically separated from charging coil
An inductive charger where the charging surface or coil is separated from the drive or control electronics is described.
1. An inductive charger for transmitting power to an inductive receiver of an electronic device for charging the electronic device, the inductive charger comprising:
a first enclosure comprising metal and having an electrically non-conductive charging surface on a side of the first enclosure, the first enclosure comprising:
an inductive charging coil positioned behind the charging surface within the first enclosure,
wherein the inductive charging coil comprises a spiral-shaped metallic Litz wire conductor that defines two charging coil terminals,
wherein the inductive charging coil has a first side that faces the charging surface and a second side that faces away from the charging surface opposite the first side, and
wherein the inductive charging coil is configured to transmit electromagnetic power by inductive power transfer through the charging surface of the enclosure with an alternating magnetic field at an operating frequency when an electronic device is positioned in proximity to the charging surface; and
a metallic second enclosure physically separated from the first enclosure, the second enclosure comprising:
a drive circuit and a resonant capacitor electrically coupled to the inductive charging coil in the first enclosure to drive the inductive charging coil with an alternating current; and
a microcontroller electrically coupled to the drive circuit, wherein the microcontroller is configured to:
detect a received communication of information in a current or voltage modulation of the inductive charger coil by the inductive receiver; and
control the transmission of power during inductive power transfer; and
a shielded electrical cable that electrically couples the first enclosure and the second enclosure,
wherein the shielded electrical cable comprises two and only two sets of twisted wires coupling the drive circuit in the second enclosure to the two charging coil terminals of the inductive charging coil in the first enclosure to drive the inductive charging coil and to receive the communication of information from the inductive charging coil,
wherein each set of the two sets of twisted wires comprises multiple electrical wires to reduce electrical loss, and
wherein the shielded electrical cable comprises a metallic shield that covers the two sets of twisted wires and is coupled to an electrical ground;
wherein the second enclosure is not within the first enclosure.
2. The inductive charger of claim 1 , wherein the charging surface comprises a polymer and a thermally conductive additive to increase the polymer's thermal conductivity.
3. The inductive charger of claim 1 , further comprising a first shield having a thermally conductive carbon-based layer positioned between the first side of the inductive charging coil and the charging surface of the first enclosure such that the first shield covers the inductive charging coil, wherein the transmission of electromagnetic power through the first shield is allowed at the operating frequency for inductive power transfer.
4. The inductive charger of claim 1 , further comprising a second shield having an electrically conductive metal layer positioned between the first side of the inductive charging coil and the charging surface of the first enclosure such that the second shield covers the inductive charging coil, wherein the metal layer has a periodic pattern and wherein the transmission of electromagnetic power through the second shield is allowed at the operating frequency for inductive power transfer.
5. The inductive charger of claim 4 , wherein the second shield further comprises a non-metallic thermally conductive layer.
6. The inductive charger of claim 5 , wherein the thermally conductive layer comprises graphite.
7. The inductive charger of claim 1 , wherein the shielded electrical cable comprises a metal foil layer and a metal coated polymer covering the two sets of twisted wires.
8. The inductive charger of claim 7 , wherein the shielded electrical cable has a length greater than or equal to 3 centimeters.
9. The inductive charger of claim 8 , wherein the two sets of twisted wires are Litz wires selected for low loss transmission of current at the operating frequency.
10. The inductive charger of claim 7 , wherein the shielded electrical cable has a length greater than or equal to 50 centimeters.
11. The inductive charger of claim 1 , further comprising a far-field charger system and a far-field antenna for far-field power transfer frequency of over 1 GHz to provide power to an electronic device positioned at a distance from the charging surface of the inductive charger.
12. The inductive charger of claim 1 , wherein the shielded electrical cable has a length greater than or equal to 3 centimeters.
13. The inductive charger of claim 1 , wherein the shielded electrical cable has a length greater than or equal to 10 centimeters.
14. The inductive charger of claim 1 , wherein the inductive charger has an operating frequency within a frequency range of 100 kHz to 1 MHz.
15. The inductive charger of claim 1 , wherein the shielded electrical cable further includes a wire distinct from the two sets of twisted wires for sensing a temperature of a component within the first enclosure by the microcontroller.
16. The inductive charger of claim 1 , wherein the electrical wires from one of the two sets of the twisted wires are twisted with electrical wires from the other set of the twisted wires to form a twisted pair.
17. An inductive charger for transmitting power to an inductive receiver of an electronic device for charging the electronic device, the inductive charger comprising:
a first enclosure comprising metal and having an electrically non-conductive charging surface on a side of the first enclosure, the first enclosure comprising:
an inductive charging coil positioned behind the charging surface within the first enclosure,
wherein the inductive charging coil comprises a spiral-shaped metallic Litz wire conductor that defines two charging coil terminals,
wherein the inductive charging coil has a first side that faces the charging surface and a second side that faces away from the charging surface opposite the first side, and
wherein the inductive charging coil is configured to transmit electromagnetic power by inductive power transfer through the charging surface of the enclosure with an alternating magnetic field at an operating frequency when an electronic device is positioned in proximity to the charging surface; and
a metallic second enclosure physically separated from the first enclosure, the second enclosure comprising:
a drive circuit and a resonant capacitor electrically coupled to the inductive charging coil in the first enclosure to drive the inductive charging coil with an alternating current; and
a microcontroller electrically coupled to the drive circuit, wherein the microcontroller is configured to:
detect a received communication of information in a current or voltage modulation of the inductive charger coil by the inductive receiver; and
control the transmission of power during inductive power transfer; and
a shielded electrical cable means that electrically couples the first enclosure and the second enclosure,
wherein the shielded electrical cable means comprises two and only two sets of twisted wires coupling the drive circuit in the second enclosure to the two charging coil terminals of the inductive charging coil in the first enclosure to drive the inductive charging coil and to receive the communication of information from the inductive charging coil,
wherein each set of the two sets of twisted wires comprises multiple electrical wires to reduce electrical loss, and
wherein the shielded electrical cable means comprises a metallic shield that covers the two sets of twisted wires and is coupled to an electrical ground;
wherein the second enclosure is not within the first enclosure.
18. The inductive charger of claim 17 , wherein the charging surface comprises a polymer and a thermally conductive additive to increase the polymer's thermal conductivity.
19. The inductive charger of claim 17 , further comprising a first shield having a thermally conductive carbon-based layer positioned between the first side of the inductive charging coil and the charging surface of the first enclosure such that the first shield covers the inductive charging coil, wherein the transmission of electromagnetic power through the first shield is allowed at the operating frequency for inductive power transfer.
20. The inductive charger of claim 17 , further comprising a second shield having an electrically conductive metal layer positioned between the first side of the inductive charging coil and the charging surface of the first enclosure such that the second shield covers the inductive charging coil, wherein the metal layer has a periodic pattern and wherein the transmission of electromagnetic power through the second shield is allowed at the operating frequency for inductive power transfer.
21. The inductive charger of claim 20 , wherein the second shield further comprises a non-metallic thermally conductive layer.
22. The inductive charger of claim 21 , wherein the thermally conductive layer comprises graphite.
23. The inductive charger of claim 17 , wherein the shielded electrical cable means comprises a metal foil layer and a metal coated polymer covering the two sets of twisted wires.
24. The inductive charger of claim 23 , wherein the shielded electrical cable means has a length greater than or equal to 3 centimeters.
25. The inductive charger of claim 24 , wherein the two sets of twisted wires are Litz wires selected for low loss transmission of current at the operating frequency.
26. The inductive charger of claim 23 , wherein the shielded electrical cable means has a length of greater than or equal to 50 centimeters.
27. The inductive charger of claim 17 , wherein the shielded electrical cable means has a length greater than or equal to 10 centimeters.
28. The inductive charger of claim 17 , wherein the inductive charger has an operating frequency within a frequency range of 100 kHz to 1 MHz.
29. The inductive charger of claim 17 , wherein the shielded electrical cable means further includes a wire distinct from the two sets of twisted wires for sensing a temperature of a component within the first enclosure by the microcontroller.
30. The inductive charger of claim 17 , wherein the electrical wires from one of the two sets of twisted wires are twisted with electrical wires from the other set of the twisted wires to form a twisted pair.
31. An inductive charger for transmitting power to an inductive receiver of an electronic device for charging the electronic device, the inductive charger comprising:
a first enclosure having an electrically non-conductive charging surface on a side of the first enclosure, the first enclosure comprising:
an inductive charging coil positioned behind the charging surface within the first enclosure,
wherein the inductive charging coil comprises a spiral-shaped metallic Litz wire conductor that defines two charging coil terminals,
wherein the inductive charging coil has a first side that faces the charging surface and a second side that faces away from the charging surface opposite the first side, and
wherein the inductive charging coil is configured to transmit electromagnetic power by inductive power transfer through the charging surface of the enclosure with an alternating magnetic field at an operating frequency when an electronic device is positioned in proximity to the charging surface; and
a metallic second enclosure physically separated from the first enclosure, the second enclosure comprising:
a drive circuit and a resonant capacitor electrically coupled to the inductive charging coil in the first enclosure to drive the inductive charging coil with an alternating current; and
a microcontroller electrically coupled to the drive circuit, wherein the microcontroller is configured to:
detect a received communication of information in a current or voltage modulation of the inductive charger coil by the inductive receiver; and
control the transmission of power during inductive power transfer; and
a shielded electrical cable that electrically couples the first enclosure and the second enclosure,
wherein the shielded electrical cable comprises two and only two sets of twisted wires coupling the drive circuit in the second enclosure to the two charging coil terminals of the inductive charging coil in the first enclosure to drive the inductive charging coil and to receive the communication of information from the inductive charging coil,
wherein each set of the two sets of twisted wires comprises multiple electrical wires to reduce electrical loss, and
wherein the shielded electrical cable comprises a metallic shield that covers the two sets of twisted wires and is coupled to an electrical ground;
wherein the second enclosure is not within the first enclosure.
32. The inductive charger of claim 31 , wherein the charging surface comprises a polymer and a thermally conductive additive to increase the polymer's thermal conductivity.
33. The inductive charger of claim 31 , wherein the electrical wires from one of the two sets of twisted wires are twisted with electrical wires from the other set of the twisted wires to form a twisted pair.
34. The inductive charger of claim 31 , wherein the shielded electrical cable comprises a metal foil layer and a metal coated polymer covering the two sets of twisted wires.
35. The inductive charger of claim 34 , wherein the shielded electrical cable has a length greater than or equal to 3 centimeters.
36. The inductive charger of claim 31 , wherein the shielded electrical cable has a length greater than or equal to 10 centimeters.
37. The inductive charger of claim 31 , wherein the inductive charger has an operating frequency within a frequency range of 100 kHz to 1 MHz.
38. The inductive charger of claim 31 , wherein the shielded electrical cable further includes a wire distinct from the two sets of twisted wires for sensing a temperature of a component within the first enclosure by the microcontroller.
39. An inductive charger for transmitting power to an inductive receiver of an electronic device for charging the electronic device, the inductive charger comprising:
a first enclosure having an electrically non-conductive charging surface on a side of the first enclosure, the first enclosure comprising:
an inductive charging coil positioned behind the charging surface within the first enclosure,
wherein the inductive charging coil comprises a spiral-shaped metallic Litz wire conductor that defines two charging coil terminals,
wherein the inductive charging coil has a first side that faces the charging surface and a second side that faces away from the charging surface opposite the first side, and
wherein the inductive charging coil is configured to transmit electromagnetic power by inductive power transfer through the charging surface of the enclosure with an alternating magnetic field at an operating frequency when an electronic device is positioned in proximity to the charging surface; and
a metallic second enclosure physically separated from the first enclosure, the second enclosure comprising:
a drive circuit and a resonant capacitor electrically coupled to the inductive charging coil in the first enclosure to drive the inductive charging coil with an alternating current; and
a microcontroller electrically coupled to the drive circuit, wherein the microcontroller is configured to:
detect a received communication of information in a current or voltage modulation of the inductive charger coil by the inductive receiver; and
control the transmission of power during inductive power transfer; and
a shielded electrical cable means that electrically couples the first enclosure and the second enclosure,
wherein the shielded electrical cable means comprises two and only two sets of twisted wires coupling the drive circuit in the second enclosure to the two charging coil terminals of the inductive charging coil in the first enclosure to drive the inductive charging coil and to receive the communication of information from the inductive charging coil,
wherein each set of the two sets of twisted wires comprises multiple electrical wires to reduce electrical loss, and
wherein the shielded electrical cable means comprises a metallic shield that covers the two sets of twisted wires and is coupled to an electrical ground;
wherein the second enclosure is not within the first enclosure.
40. The inductive charger of claim 39 , wherein the charging surface comprises a polymer and a thermally conductive additive to increase the polymer's thermal conductivity.
41. The inductive charger of claim 39 , wherein the shielded electrical cable means comprises a metal foil layer and a metal coated polymer covering the two sets of twisted wires.
42. The inductive charger of claim 41 , wherein the shielded electrical cable means has a length of greater than or equal to 3 centimeters.
43. The inductive charger of claim 41 , wherein the shielded electrical cable means has a length greater than or equal to 50 centimeters.
44. The inductive charger of claim 39 , wherein the inductive charger has an operating frequency within a frequency range of 100 kHz to 1 MHz.
45. The inductive charger of claim 39 , wherein the shielded electrical cable means further includes a wire distinct from the two sets of twisted wires for sensing a temperature of a component within the first enclosure by the microcontroller.
46. The inductive charger of claim 39 , wherein the electrical wires from one of the two sets of twisted wires are twisted with electrical wires from the other set of the twisted wires to form a twisted pair.
47. An inductive charger for transmitting power to an inductive receiver of an electronic device for charging the electronic device, the inductive charger comprising:
a first enclosure comprising metal and having an electrically non-conductive charging surface on a side of the first enclosure, the first enclosure comprising:
an inductive charging coil positioned behind the charging surface within the first enclosure,
wherein the inductive charging coil comprises a spiral-shaped Printed Circuit Board (PCB) coil with two charging coil terminals,
wherein the inductive charging coil has a first side that faces the charging surface and a second side that faces away from the charging surface opposite the first side, and
wherein the inductive charging coil is configured to transmit electromagnetic power by inductive power transfer through the charging surface of the enclosure with an alternating magnetic field at an operating frequency when an electronic device is positioned in proximity to the charging surface; and
a metallic second enclosure physically separated from the first enclosure, the second enclosure comprising:
a drive circuit and a resonant capacitor electrically coupled to the inductive charging coil in the first enclosure to drive the inductive charging coil with an alternating current; and
a microcontroller electrically coupled to the drive circuit, wherein the microcontroller is configured to:
detect a received communication of information in a current or voltage modulation of the inductive charger coil by the inductive receiver; and
control the transmission of power during inductive power transfer; and
a shielded electrical cable that electrically couples the first enclosure and the second enclosure,
wherein the shielded electrical cable comprises two and only two sets of twisted wires coupling the drive circuit in the second enclosure to the two charging coil terminals of the inductive charging coil in the first enclosure to drive the inductive charging coil and to receive the communication of information from the inductive charging coil,
wherein each set of the two sets of twisted wires comprises multiple electrical wires to reduce electrical loss, and
wherein the shielded electrical cable comprises a metallic shield that covers the two sets of twisted wires and is coupled to an electrical ground;
wherein the second enclosure is not within the first enclosure.
48. The inductive charger of claim 47 , further comprising a first shield having an electrically conductive metal layer positioned between the first side of the inductive charging coil and the charging surface of the first enclosure such that the first shield covers the inductive charging coil, wherein the metal layer has a periodic pattern and wherein the transmission of electromagnetic power through the first shield is allowed at the operating frequency for inductive power transfer.
49. The inductive charger of claim 47 , wherein the shielded electrical cable comprises a metal foil layer and a metal coated polymer covering the two sets of twisted wires.
50. The inductive charger of claim 49 , wherein the shielded electrical cable has a length greater than or equal to 3 centimeters.
51. The inductive charger of claim 50 , wherein the two sets of twisted wires are Litz wires selected for low loss transmission of current at the operating frequency.
52. The inductive charger of claim 49 , wherein the shielded electrical cable has a length of greater than or equal to 50 centimeters.
53. The inductive charger of claim 47 , wherein the electrical wires from one of the two sets of twisted wires are twisted with electrical wires from the other set of the twisted wires to form a twisted pair.