Charging device having small loop transmission coils for wireless charging a target device

• US 10,097,031 B2
• Filed: 09/20/2016
• Issued: 10/09/2018
• Est. Priority Date: 09/20/2016
• Status: Active Grant

• Current Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Original Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Inventors: Liu, Yan, Chen, Jun
• Primary Examiner(s): Parihar, Suchin
• Application Number:
  US15/270,681
• Publication Number:
  US 20180083475A1
• Time in Patent Office: 749 Days
• Field of Search: 320108
• 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 50/12 of the resonant type

Abstract

A charging device to wirelessly charge a target device, including: a coil antenna having a first surface facing a first direction at which the target device is placed for charging and a second surface facing an opposite direction from the first direction, generating a first magnetic field; a plurality of pairs of metallic small loop transmission coils arranged to the second surface side of the coil antenna, to generate a second magnetic field in response to the first magnetic field to enhance the first magnetic field, the first and second magnetic fields being directed in the first direction; and wherein a first one of each pair of metallic small loop transmission coils is coupled to a second one of the pair in parallel and a size of the first one of each pair is different from that of the second one of the pair, such that when a distance between the target device and the first surface is changed, one of the pair of metallic small loop transmission coils is enabled to be resonant with the coil antenna.

Claims

1. A charging device to wirelessly charge a target device, comprising:

a coil antenna having a first surface facing a first direction at which the target device is placed for charging and a second surface facing an opposite direction from the first direction, generating a first magnetic field;

a plurality of pairs of metallic small loop transmission coils arranged to the second surface side of the coil antenna, to generate a second magnetic field in response to the first magnetic field to enhance the first magnetic field, the first and second magnetic fields being directed in the first direction; and

wherein a first one of each pair of metallic small loop transmission coils is coupled to a second one of the pair in parallel and a size of the first one of each pair is different from that of the second one of the pair, such that when a distance between the target device and the first surface is changed, one of the pair of metallic small loop transmission coils is enabled to be resonant with the coil antenna, and

wherein inductance and capacitance values, for each metallic small loop transmission coil, with a number of turns N, turn width W, spacing between turn S, inner diameter D1, outer diameter D2, inductance L, capacitance C, and frequency f, the inductance L_loop and capacitance C_total are determined by formula (1) below;

2. The charging device of claim 1, wherein the size of each of the metallic small loop transmission coils is predesigned to enable the corresponding small loop transmission coil to be resonant with the coil antenna in response to a distance between the target device and the coil antenna being a corresponding predefined target distance.

3. The charging device of claim 1, wherein each of the first and second metallic small loop transmission coils of the pairs of metallic small loop transmission coils is one of a rectangle, circle, polygon, square, triangle or any combination thereof, and each first metallic transmission loop coil has a different shape from the corresponding second metallic transmission loop coil.

4. The charging device of claim 1, further comprising capacitors respectively connected to each small loop transmission coil in series.

5. The charging device according to claim 4, wherein the capacitors are gaps.

6. The charging device according to claim 4, wherein the capacitors are ceramic capacitors.

7. The charging device of claim 1, wherein the first one of each pair of metallic small loop transmission coils is located within the second one of the pair.

8. The charging device according to claim 1, wherein the first one of each pair of metallic small loop transmission coils is smaller than the second one of the pair, and located to a side of the second one of the pair.

9. The charging device according to claim 1, wherein the first ones of each pair of small loop transmission coils have the same size and shape, and the second ones of each pair of small loop transmission coils have the same size and shape, and the ones of the same small loop pair have a different size and different shape.

10. The charging device of claim 1, wherein the metallic small loop transmission coils are designed in accordance with:

determining a first set of D1, D2, W and S for the first one of each pair of metallic small loop transmission coils based upon a size of the coil antenna and a quantity of the pairs of metallic small loop transmission coils and calculating a first loop inductance;

calculating a first series capacitor value for the first capacitor of the first metallic small loop transmission coil according to formula (1);

building a simulation model to fine tune the first capacitor;

determining a second set of D1, D2, W and S for the second one of each pair of metallic small loop transmission coils based upon a size of the first one of the pair of metallic small loop transmission coils and calculating a second loop inductance;

calculating a second series capacitor value for the second capacitor of the second metallic small loop transmission coil according to formula (1);

building a simulation model to fine tune the second capacitor based upon predetermined distances set for between the coil antenna and the target device; and

combining the first and second metallic small loop transmission coils in parallel, and fine tune the first and second capacitors.

11. The charging device according to claim 1, wherein each pair of metallic small loop transmission coils comprises at least 2 metallic small loop transmission coils connected in parallel to each other.

12. The charging device according to claim 1, wherein each pair of metallic small loop transmission coils comprises at least 3 metallic small loop transmission coils connected in parallel to each other.

13. A method of wirelessly charging a target device, comprising:

generating a first magnetic field from a second surface of a coil antenna, the coil antenna having a first surface facing a first direction at which the target device is placed for charging and the second surface facing an opposite direction from the first direction; and

generating a second magnetic field using a plurality of pairs of metallic small loop transmission coils arranged to the second surface side of the coil antenna in response to the first magnetic field, the first and second magnetic fields being directed in the first direction;

wherein a first one of each pair of metallic small loop transmission coils is coupled to a second one of the pair in parallel and a size of the first one of each pair is different from that of the second one of the pair, such that when a distance between the target device and the first surface is changed, one of the pair of metallic small loop transmission coils is enabled to be resonant with the coil antenna

wherein capacitors are respectively connected to each small loop transmission coil in series, and

wherein inductance and capacitance values, for each metallic small loop transmission coil, with a number of turns N, turn width W, spacing between turn S, inner diameter D1, outer diameter D2, inductance L, capacitance C, and frequency f, the inductance L_loop and capacitance C_total are determined by formula (1) below;

14. The method of claim 13, wherein the size and/or shape of each of the metallic small loop transmission coils are predesigned to enable the corresponding small loop transmission coil to be resonant with the coil antenna in response to a distance between the target device and the coil antenna being a corresponding predefined target distance.

15. The method of claim 13, wherein each of the first and second metallic small loop transmission coils of the pairs of metallic small loop transmission coils is one of a rectangle, circle, polygon, square, triangle or any combination thereof, and each first metallic transmission loop coil has a different shape from the corresponding second metallic transmission loop coil.

16. The method of claim 13, wherein the metallic small loop transmission coils are designed in accordance with:

determining a first set of D1, D2, W and S for the first one of each pair of metallic small loop transmission coils based upon a size of the coil antenna and a quantity of the pairs of metallic small loop transmission coils and calculating a first loop inductance;

calculating a first series capacitor value for the first capacitor of the first metallic small loop transmission coil according to formula (1);

building a simulation model to fine tune the first capacitor;

determining a second set of D1, D2, W and S for the second one of each pair of metallic small loop transmission coils based upon a size of the first one of the pair of metallic small loop transmission coils and calculating a second loop inductance;

calculating a second series capacitor value for the second capacitor of the second metallic small loop transmission coil according to formula (1);

building a simulation model to fine tune the second capacitor based upon predetermined distances set for between the coil antenna and the target device; and

combining the first and second metallic small loop transmission coils in parallel, and fine tune the first and second capacitors.

17. The method according to claim 13, wherein the first ones of each pair of small loop transmission coils have the same size and shape, and the second ones of each pair of small loop transmission coils have the same size and shape, and the ones of the same small loop pair have a different size and different shape.

18. A method of designing a charging device to wirelessly charge a target device, comprising:

a coil antenna having a first surface facing a first direction at which the target device is placed for charging and a second surface facing an opposite direction from the first direction, generating a first magnetic field;

a plurality of pairs of metallic small loop transmission coils arranged to the second surface side of the coil antenna, to generate a second magnetic field in response to the first magnetic field to enhance the first magnetic field, the first and second magnetic fields being directed in the first direction; and

wherein a first one of each pair of metallic small loop transmission coils is coupled to a second one of the pair in parallel and a size of the first one of each pair is different from that of the second one of the pair, such that when a distance between the target device and the first surface is changed, one of the pair of metallic small loop transmission coils is enabled to be resonant with the coil antenna, the method comprising;

determining inductance and capacitance values, for each metallic small loop transmission coil, with a number of turns N, turn width W, spacing between turn S, inner diameter D1, outer diameter D2, inductance L, capacitance C, and frequency tf, the inductance L_loop and capacitance C_total by formulae (1) and (2) below;