Flush-mount wireless charging power-transfer system

• US 10,819,156 B2
• Filed: 11/01/2018
• Issued: 10/27/2020
• Est. Priority Date: 12/05/2017
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: WiTricity Corporation
• Inventors: Zaheer, Adeel, Keeling, Nicholas Athol
• Primary Examiner(s): Dinh, Paul
• Application Number:
  US16/178,559
• Publication Number:
  US 20190173317A1
• Time in Patent Office: 726 Days
• Field of Search: 320109
• CPC Class Codes: H01F 27/255 made from particles H01F27/26 takes precedence
• CPC Class Codes: H01F 27/306 Fastening or mounting coils or windings on core, casing or other support
• CPC Class Codes: H01F 3/10 Composite arrangements of magnetic circuits
• CPC Class Codes: H01F 3/14 Constrictions; Gaps, e.g. air-gaps in magnetic shunt paths H01F3/12
• 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 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 7/0042 characterised by the mechanical construction
• CPC Class Codes: H02J 7/16 Regulation of the charging current or voltage by variation of field
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

Systems and methods are described for a flush mount wireless charging power-transfer system. The techniques described in this document provide high mutual inductance with low leakage fields. These techniques also provide low surface flux densities in a base power transfer system, particularly for a component of a magnetic field that is tangential to the surface of the base power transfer system. Aspects include mechanical gaps located between ferrite structures in the coil window in the base power transfer system, and protrusions of ferrite on opposing sides of each gap. In addition, ferrite extensions are located beyond an outer boundary of the coil (e.g., in an x-direction) and extend upward above the plane of the coil (e.g., in a z-direction). The gaps, protrusions, and extensions separate the main flux from the side flux, reduce flux leakage, and improve mutual inductance between the base pad and a vehicle pad.

Claims

1. A wireless charging apparatus comprising:

a coil configured to generate a magnetic field, the coil defining a coil plane and having a coil window, the coil having opposing top and bottom surfaces;

a plurality of ferrite structures located proximate to the bottom surface of the coil, the plurality of ferrite structures configured to provide a path for magnetic flux of the magnetic field, the plurality of ferrite structures including a first ferrite structure and a second ferrite structure separated by a gap;

a ferrite protrusion disposed on each opposing side of the gap and connected to one of the plurality of ferrite structures, the ferrite protrusion extending into the coil window within the coil plane; and

a ferrite extension disposed on at least one of the plurality of ferrite structures and located outside a boundary of the coil, the ferrite extension extending above the top surface of the coil.

2. The wireless charging apparatus as described in claim 1, wherein the plurality of ferrite structures form rows that run longitudinally in a direction of a polarization of the magnetic field.

3. The wireless charging apparatus as described in claim 1, wherein the gap that separates the first ferrite structure and the second ferrite structure extends in a direction perpendicular to the direction of a polarization of the magnetic field.

4. The wireless charging apparatus as described in claim 1, wherein the gap that separates the first ferrite structure and the second ferrite structure increases a magnetic reluctance of the path of the magnetic flux effective to separate main flux from side flux.

5. The wireless charging apparatus as described in claim 1, wherein the gap that separates the first ferrite structure and the second ferrite structure is located in the coil window.

6. The wireless charging apparatus as described in claim 1, wherein the gap that separates the first ferrite structure and the second ferrite structure is larger than manufacturing tolerances.

7. The wireless charging apparatus as described in claim 1, wherein the gap that separates the first ferrite structure and the second ferrite structure is located at a position corresponding to a portion of the magnetic flux that is substantially-vertical through the coil window.

8. The wireless charging apparatus as described in claim 1, wherein the gap is defined between the first ferrite structure and the second ferrite structure sufficient to interrupt a continuous flux path between the first ferrite structure and the second ferrite structure.

9. The wireless charging apparatus as described in claim 1, wherein the ferrite protrusion intersects the coil plane and extends above the coil plane.

10. The wireless charging apparatus as described in claim 1, wherein the ferrite protrusion is configured to steer a portion of the magnetic flux in a direction substantially normal to the coil plane effective to strengthen a coupling between the wireless charging apparatus and a vehicle wireless charging system.

11. The wireless charging apparatus as described in claim 1, wherein the ferrite extension extends above the top surface of the coil in a direction normal to the coil plane.

12. The wireless charging apparatus as described in claim 1, wherein:

the coil is a first coil disposed proximate to a second coil, the first coil being coplanar with the second coil;

the plurality of ferrite structures includes a third ferrite structure separated from the second ferrite structure by an additional gap positioned to overlap with an additional coil window of the second coil;

the third ferrite structure is connected to an additional ferrite extension and an additional ferrite protrusion;

the additional ferrite extension is located outside an outer boundary of the second coil and extends above the coil plane; and

the additional ferrite protrusion is located proximate to the additional gap and extends into the coil plane within the additional coil window of the second coil.