Inductive power transfer system

• US 10,566,838 B2
• Filed: 08/06/2010
• Issued: 02/18/2020
• Est. Priority Date: 08/07/2009
• Status: Active Grant

• Current Assignee: Auckland UniServices Limited (Auckland University)
• Original Assignee: Auckland UniServices Limited (Auckland University)
• Inventors: Covic, Grant Anthony, Kissin, Michael Le Gallais
• Primary Examiner(s): Amaya, Carlos
• Application Number:
  US13/389,090
• Publication Number:
  US 20120248892A1
• Time in Patent Office: 3,483 Days
• Field of Search: 307104
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 5/005 without mechanical contact between the collector and the power supply line
• CPC Class Codes: B60L 53/12 Inductive energy transfer
• CPC Class Codes: B60L 53/122 Circuits or methods for driving the primary coil, e.g. supplying electric power to the coil
• CPC Class Codes: B60L 53/126 Methods for pairing a vehicle and a charging station, e.g. establishing a one-to-one relation between a wireless power transmitter and a wireless power receiver
• 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 50/005 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 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• 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 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

A magnetic flux pad (BPP) is provided for generating or receiving magnetic flux. The pad may be used with an inductive power transfer system, and comprises a magnetically permeable core (4) and two substantially flat overlapping coils (2, 3) magnetically associated with the core (4). The coils (2, 3) are arranged so that there is essentially no mutual coupling between them.

Claims

1. A magnetic flux pad for generating or receiving magnetic flux, the magnetic flux pad comprising:

a magnetically permeable material comprising a plurality of ferrite strips; and

two substantially overlapping coils sitting on top of the magnetically permeable material and magnetically associated with the magnetically permeable material, whereby the overlap of the coils is adjusted to substantially minimize mutual coupling between the coils.

2. A magnetic flux pad as claimed in claim 1 wherein the coils are substantially completely magnetically decoupled.

3. A magnetic flux pad as claimed in claim 1 wherein the coils partially overlap.

4. A magnetic flux pad as claimed in claim 1 wherein the coils are substantially coplanar.

5. A magnetic flux pad as claimed in claim 1 wherein the coils are provided on one side of the magnetic permeable material, and a shielding means is provided on the other side of the magnetic permeable material.

6. A magnetic flux pad as claimed in claim 5 wherein the shielding means comprises a shielding plate made of a suitable aluminum material.

7. A magnetic flux pad as claimed in claim 1 further comprising a dielectric cover provided on a side of the coils opposite the magnetically permeable material.

8. A magnetic flux pad as claimed in claim 1 wherein the flux pad is adapted to receive currents from a power supply which are out-of-phase with each other to produce a time varying magnetic field which also varies spatially.

9. A magnetic flux pad as claimed in claim 8 wherein the time varying magnetic field produced by the out-of-phase currents in the coils produces a time varying magnetic field which moves spatially and alternately between poles.

20. A magnetic flux pad as claimed in claim 2 wherein the coils partially overlap.

23. A magnetic flux pad as claimed in claim 1 wherein the magnetically permeable material includes a plurality of lengths of permeable material.

24. A magnetic flux pad as claimed in claim 23 wherein the lengths of permeable material are arranged parallel to, but spaced apart from, each other.

25. A magnetic flux pad as claimed in claim 24 wherein the lengths of permeable material extend under an entirety coils.

28. A magnetic flux pad as claimed in claim 1 configured to generate a magnetic field to provide power to a vehicle.

10. A power supply apparatus for an inductive power transfer system (IPT), the power supply apparatus comprising:

a magnetic flux pad for generating a magnetic flux, the magnetic flux pad comprising a magnetically permeable material comprising a plurality of ferrite strips, two substantially overlapping coils sitting on top of the magnetically permeable material and magnetically associated with the magnetically permeable material; and

a power supply adapted to provide a current in one of the overlapping coils which has a different phase to a current in the other of the overlapping coils.

11. A power supply apparatus as claimed in claim 10 wherein the power supply is adapted to adjust the phase to produce a field that varies with time and with spatial position on the magnetic flux pad.

12. A power supply apparatus as claimed in claim 10 further comprising means to detect where a field is or is not required in a vicinity of the magnetic flux pad and adjust relative phase and/or amplitude of the current in the overlapping coils in response to an output of a sensing means.

13. A power supply apparatus as claimed in claim 10 wherein the power supply includes an inverter for each of the overlapping coils.

14. A power supply apparatus as claimed in claim 10 wherein the power supply comprises two inverters which are synchronized with each other to produce a current in the one of the overlapping coils which is 90°

out of phase with the current in the other of the overlapping coils.

15. A power supply apparatus as, claimed in claim 10 wherein the magnetic flux pad produces a sliding time varying magnetic field.

16. A power supply apparatus as claimed in claim 10 wherein the power supply operates the overlapping coils 180°

out of phase with each other.

17. A power supply apparatus as claimed in claim 16 wherein the power supply includes one inverter for energizing both coils.

21. A power supply apparatus as claimed in claim 11 further comprising means to detect where a field is or is not required in a vicinity of the magnetic flux pad and adjust relative phase and/or amplitude of the current in the overlapping coils in response to an output of a sensing means.

22. A power supply apparatus as claimed in claim 13 wherein the power supply comprises two inverters which are synchronized with each other to produce a current in the one of the overlapping coils which is 90°

out of phase with the current in the other of the overlapping coils.

26. A power supply apparatus as claimed in claim 10 wherein the overlap between the overlapping coils is adjusted to reduce mutual coupling between the coils.

18. A method for providing an Inductive Power Transfer (IPT) magnetic flux pad comprising a plurality of ferrite strips and two coils sitting on top of the plurality of ferrite strips, the method comprising:

overlapping the coils, and

varying the overlap between the coils such that an overlap position is achieved whereby mutual coupling between the coils is substantially minimized.

19. A method as claimed in claim 18 wherein absence of mutual coupling is detected by detecting when an open circuit voltage induced in one of the coils by energization of the other coil is minimized.

27. A method as claimed in claim 18 further comprising overlapping the coils in presence of a permeable magnetic material.