EMI FILTERING AND WIRELESS POWER TRANSFER IN AN ELECTRONIC DEVICE USING A TUNED METALLIC BODY

• US 20170222467A1
• Filed: 09/14/2016
• Published: 08/03/2017
• Est. Priority Date: 01/29/2016
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wheatley, Charles Edward, White, II, Mark, Jeong, Seong Heon, Carobolante, Francesco
• Granted Patent: US 10,312,716 B2
• Time in Patent Office: Days
• CPC Class Codes: H01F 27/02 Casings
• CPC Class Codes: H01F 27/34 Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
• CPC Class Codes: H01F 27/366 made of ferromagnetic material
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

An apparatus may include an electrically conductive body to magnetically couple to a first magnetic field. A first tuning element may be connected to the electrically conductive body. An electrically conductive coil may be wound about an opening in the electrically conductive body, and configured to magnetically couple to a second magnetic field.

Claims

1. An apparatus for wireless power transfer, the apparatus comprising:

an electrically conductive body forming a portion of a cover or housing of the apparatus, the electrically conductive body configured to magnetically couple to a first magnetic field generated by a wireless power transmitter;

a first tuning element comprising a capacitor and electrically connected to the electrically conductive body; and

an electrically conductive coil wound about an opening defined by the electrically conductive body, the electrically conductive coil configured to magnetically couple to a second magnetic field generated by the electrically conductive body, the first tuning element and the electrically conductive body defining a filter circuit configured to filter harmonics generated by electronic components of the apparatus.

2. The apparatus of claim 1, wherein the electronic components comprise power conversion circuitry configured to power or charge a load using a received current generated in the electrically conductive coil in response to coupling to the second magnetic field, wherein the filter circuit is configured to filter harmonics generated by the power conversion circuitry.

3. The apparatus of claim 2, wherein the power conversion circuitry comprises a rectifier configured to rectify current induced in the electrically conductive coil to provide power to the load, wherein the filter circuit is configured to filter harmonics generated by the rectifier.

4. The apparatus of claim 1, wherein the harmonics fall within a frequency band of a cellular signal received or transmitted by the apparatus.

5. The apparatus of claim 1, wherein the filter circuit comprises at least one of:

a low-pass filter having a cutoff frequency of an integer multiple of a fundamental power transfer frequency of the first magnetic field;

or

a notch filter having a center frequency of an integer multiple of the fundamental power transfer frequency.

6. The apparatus of claim 1, further comprising a first reactive element electrically connected between the electrically conductive body and the electrically conductive coil.

7. The apparatus of claim 6, further comprising a second reactive element electrically connected between the electrically conductive body and the electrically conductive coil in parallel with the first reactive element.

8. The apparatus of claim 7, wherein the first and second reactive elements are electrically connected to the first tuning element such that the first and second reactive elements form a portion of the filter circuit.

9. The apparatus of claim 1, wherein the electrically conductive body is configured to generate the second magnetic field in response to eddy currents induced in the electrically conductive body in response to coupling to the first magnetic field.

10. The apparatus of claim 1, wherein the electrically conductive body defines a slot that extends from the opening to a periphery of the electrically conductive body.

11. The apparatus of claim 10, wherein the capacitor is electrically connected between a first node on a first side of the slot and a second node on a second side of the slot.

12. The apparatus of claim 11, wherein the capacitor is a first capacitor and wherein the apparatus further comprises a second capacitor electrically connected between the first node and the electrically conductive coil.

13. The apparatus of claim 12, further comprising a third capacitor electrically connected between the second node and the electrically conductive coil.

14. The apparatus of claim 13, further comprising a fourth capacitor electrically connected to the electrically conductive coil.

15. The apparatus of claim 1, further comprising a second tuning element electrically connected to the electrically conductive coil to define a circuit having a resonant frequency substantially equal to a resonant frequency of the resonant circuit formed by the electrically conductive body and the first tuning element.

16. The apparatus of claim 1, further comprising a second tuning element electrically connected to the electrically conductive coil to define a circuit having a resonant frequency different from a resonant frequency of the resonant circuit formed by the electrically conductive body and the first tuning element.

17. The apparatus of claim 1, further comprising a metallic enclosure configured to house the electronic components, the metallic enclosure comprising the electrically conductive body.

18. The apparatus of claim 1, wherein the first tuning element further comprises an inductor electrically connected to the capacitor.

19. The apparatus of claim 1, wherein the capacitor comprises a variable capacitor.

20. A method for wireless power transfer in an electronic device, the method comprising:

magnetically coupling to an externally generated magnetic field via an electrically conductive body, that forms a portion of a housing for the electronic device, to produce an induced magnetic field that emanates from the electrically conductive body;

magnetically coupling to the induced magnetic field via a power receiving element to induce current in the power receiving element to power or charge a load, the second power receiving element being electrically isolated from the electrically conductive body; and

filtering harmonics generated by the power receiving element via a filter circuit comprising the electrically conductive body electrically connected to a tuning element.

21. The method of claim 20, wherein the harmonics fall within a frequency band of a cellular signal received by the electronic device.

22. An apparatus for wirelessly receiving power, the apparatus comprising:

a housing configured to enclose electronic components of the apparatus, the housing comprising a metallic sheet having a shape that defines an opening therethrough and a slot extending from the opening to a periphery of the metallic sheet;

a first tuning element electrically connected between a first node on the metallic sheet positioned on a first side of the slot and a second node on the metallic sheet on a second side of the slot, the metallic sheet having a shape that allows a flow of current to be induced therein in response to being magnetically coupled to a first magnetic field;

an electrically conductive coil wound about the opening and configured such that a flow of current will be induced in the electrically conductive coil in response to being magnetically coupled to a second magnetic field, generated by the flow of current in the metallic sheet, to produce a flow of current in the electrically conductive coil;

power conversion circuitry configured to produce power from the flow of current induced in the electrically conductive coil; and

a filter circuit comprising the metallic sheet and the first tuning element, the filter circuit configured to filter harmonics generated by the power conversion circuitry.

23. The apparatus of claim 22, wherein the harmonics fall within a frequency band of a cellular signal received by the apparatus.

24. The apparatus of claim 22, wherein the filter circuit comprises at least one of:

a low-pass filter having a cutoff frequency of an integer multiple of a fundamental power transfer frequency of the first magnetic field;

or

a notch filter having a center frequency of an integer multiple of the fundamental power transfer frequency.

25. The apparatus of claim 22, wherein the first tuning element comprises a first capacitor, wherein the apparatus further comprises:

a second capacitor electrically connected between the first node and the electrically conductive coil; and

a third capacitor electrically connected between the second node and the electrically conductive coil.

26. The apparatus of claim 25, wherein the second and third capacitor form a portion of the filter circuit.

27. The apparatus of claim 22, further comprising a second tuning element electrically connected to the electrically conductive coil to define a circuit having a resonant frequency substantially equal to a resonant frequency of the resonant circuit formed by the metallic sheet and the first tuning element.

28. An apparatus for wireless power transfer, the apparatus comprising:

electrically conductive means for housing the apparatus, the electrically conductive means configured to magnetically couple to a first magnetic field generated by a wireless power transmitter and to produce a second magnetic field in response thereto;

means for tuning the electrically conductive means;

means for magnetically coupling power to power or charge a load from the second magnetic field generated by the electrically conductive means for housing the apparatus; and

means for filtering harmonics via the electrically conductive means and the means for tuning the electrically conductive means.

29. The apparatus of claim 28, wherein the harmonics fall within a frequency band of a cellular signal received by the apparatus.