CIRCUIT FOR A SYSTEM FOR CONTACTLESS INDUCTIVE POWER TRANSMISSION

• US 20130187595A1
• Filed: 05/27/2011
• Published: 07/25/2013
• Est. Priority Date: 06/02/2010
• Status: Active Grant

• Current Assignee: Friedrich-Alexander-Universitat Erlangen-Nurnberg
• Original Assignee: Friedrich-Alexander-Universitat Erlangen-Nurnberg, Friwo Gerätebau GmbH
• Inventors: Durbaum, Thomas, Bucher, Alexander
• Granted Patent: US 9,502,921 B2
• Time in Patent Office: Days
• US Class Current: 320/108
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

The invention relates to a circuit for a system for contactless, inductive power transmission, in particular for use in supplying power to mobile devices, and to an associated charging circuit. The circuit comprises a primary-side circuit, which is disposed on a primary side and can be connected to a primary-side supply voltage, and a secondary-side circuit, which is disposed on a secondary side and can be connected to a load to be supplied with power. Furthermore a transformer stage having galvanic isolation is provided for the contactless transfer of power from the primary side over an air gap to the secondary side, wherein at least two magnetically coupled coils are provided for inductive power transmission and can be spatially separated from one another by distancing the secondary side from the primary side. The transformer stage has a resonant converter and the secondary-side circuit further comprises a restabilisation stage.

Claims

1. A circuit for a system for contactless inductive energy transfer, wherein the circuit comprises:

a primary side circuit being arranged on the primary side that can be connected to a supply voltage on the primary side, and a secondary side circuit being arranged on the secondary side that can be connected to a load which is to be supplied with energy;

a conductor stage with galvanic separation for contactless transfer of energy from the primary side to the secondary side via an air gap, wherein at least two magnetically coupled inductors for inductive energy transfer are provided which are spatially separable from one another by removing the secondary side from the primary side;

wherein the conductor stage comprises a resonant converter and the secondary side circuit further comprises a subsequent stabilising stage.

2. The circuit according to claim 1, wherein the circuit is operable such that an initial voltage of the conductor stage is maintained in a predetermined value range in case of variations of the load to be supplied, of the supply voltage and/or a distance between the primary side and the secondary side, without providing a continuous feedback of information to the primary side via the initial voltage.

3. The circuit according to claim 1, wherein the resonant converter is adapted to change a operating condition only in response to changes of electric properties on the primary side.

4. The circuit according to claim 3, wherein the resonant converter comprises a LLCC-converter or a LLC-converter.

5. The circuit according to claim 3, that can be operated such that a switching frequency of the conductor stage is adjusted to a bias point, dependent on at least one electric property of the primary side.

6. The circuit according to claim 3, wherein the resonant converter can be operated with a fixed frequency.

7. The circuit according to claim 6, wherein the resonant converter is operated such that a duty factor of the conductor stage changes dependent on at least one electric property of the primary side.

8. The circuit according to claim 1, wherein the subsequent stabilisation stage is provided such that it can limit a load current and/or a load voltage.

9. The circuit according to claim 1, wherein the subsequent stabilisation stage is provided such that a significant but limited ripple content of the rectified voltage on the secondary side can be removed.

10. The circuit according to claim 1, wherein the subsequent stabilisation stage is provided such that its initial voltage or its initial current is adjustable for sensitive loads in narrow limits.

11. The circuit according to claim 1, wherein the subsequent stabilisation stage is provided such that its power removal is limited in case of great distances when a significant drop in the DC-voltage on the secondary side occurs.

12. The circuit according to claim 1, wherein the subsequent stabilising stage comprises a DC-DC-converter.

13. The circuit according to claim 12, wherein the subsequent stabilising stage comprises a Buck-Boost-converter, a Boost-converter, a Cuk-converter or a galvanically separated converter.

14. The circuit according to claim 12, wherein the subsequent stabilising stage comprises a Flyback-converter, a forward-converter or another galvanically separated converter.

15. The circuit according to claim 1, wherein the primary side circuit comprises a pre-processing stage in form of a diode bridge for pre-processing of the supply-voltage.

16. The circuit according to claim 15, wherein the primary side conductor stage is supplied with a time dependent voltage, which approximately follows the line voltage, without providing a continuous feedback of information to the primary side via the initial voltage on the secondary side.

17. The circuit according to claim 16, wherein the primary side conductor stage is provided as LLCC-converter, without a continuous feedback of information to the primary side via the initial voltage on the secondary side taking place.

18. The circuit according to claim 17, wherein the primary side conductor stage is provided as LLCC-converter being operated with a fixed frequency, without a continuous feedback of information to the primary side via the initial voltage on the secondary side taking place.

19. The circuit according to claim 15, wherein the primary side pre-processing stage comprises a rectifier bridge and storage capacitor being parallel-connected to an initial voltage of the rectifier bridge, wherein a smoothening inductor for raising the power factor is provided.

20. The circuit according to claim 15, wherein the primary side pre-processing stage comprises an AC-DC-converter for active power factor correction and/or a DC-DC-converter.

21. The circuit according to claim 20, wherein the primary side pre-processing stage comprises a Buck-converter, a Buck-Boost-converter or a Boost-converter.

22. The circuit according to claim 1, wherein the subsequent stabilising stage comprises a Buck-converter and the conductor stage being formed by a LLC- or LLCC-converter operated at a fixed frequency, which is supplied by a Boost-converter from the rectified power supply, the Boost-converter being either an AC-DC-converter or a DC-DC-converter.

23. The circuit according to claim 1, wherein the primary side circuit is integrable in a base part and the secondary side circuit is integrable in a mobile part.

24. The charging circuit according to claim 1, adapted to charge at least one rechargeable accumulator.