WIRELESS POWER CHARGING USING POINT OF LOAD CONTROLLED HIGH FREQUENCY POWER CONVERTERS

• US 20130214591A1
• Filed: 01/11/2013
• Published: 08/22/2013
• Est. Priority Date: 02/14/2012
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Miller, John M., Chambon, Paul H., Seiber, Larry E., White, Clifford P., Campbell, Steven L.
• Granted Patent: US 9,156,364 B2
• Time in Patent Office: Days
• US Class Current: 307/9.1
• 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: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• 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 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• 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

An apparatus for wirelessly charging a battery of an electric vehicle is provided with a point of load control. The apparatus includes a base unit for generating a direct current (DC) voltage. The base unit is regulated by a power level controller. One or more point of load converters can be connected to the base unit by a conductor, with each point of load converter comprising a control signal generator that transmits a signal to the power level controller. The output power level of the DC voltage provided by the base unit is controlled by power level controller such that the power level is sufficient to power all active load converters when commanded to do so by any of the active controllers, without generating excessive power that may be otherwise wasted.

Claims

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

an active front end unit configured to provide a unipolar output voltage;

a buck-boost converter configured to receive said unipolar output voltage and to generate a DC supply voltage to at least one DC power transmission cable;

an output power controller that determines a load level of electrical power to be wirelessly transmitted and controls an output power level provided by said DC supply voltage to said at least one DC power transmission cable; and

at least one point-of-load converter, each comprising a high frequency alternating current (AC) current generation circuit that is connected to one of said at least one DC power transmission cable and is configured to provide AC current through at least one power transmission circuit, wherein each of said at least one power transmission circuit comprises a primary coil for wireless power transfer.

2. The apparatus of claim 1, wherein said output power controller maintains said DC supply voltage substantially constant irrespective of variations in said output power level.

3. The apparatus of claim 2, wherein said buck-boost converter comprises a set of current switching devices, and said output power controller changes a duty cycle of said set of current switching devices in linear proportion to said determined load level of electrical power to be wirelessly transmitted.

4. The apparatus of claim 3, wherein said set of current switching devices comprises a pair of field effect transistors connected in a series connection across an output node for said unipolar output voltage and electrical ground.

5. The apparatus of claim 1, wherein said buck-boost converter comprises an output stage that includes a series connection of an inductor and a capacitor, and said DC supply voltage is provided at a node between said inductor and said capacitor.

6. The apparatus of claim 1, wherein said at least one point-of-load converter is a plurality of point-of-load converters.

7. The apparatus of claim 6, wherein said output power controller is configured to switch on only a subset of said plurality of point-of-load converters having a vehicle within a wireless power transfer (WPT) field thereof.

8. The apparatus of claim 6, wherein said output power controller is configured to identify an incremental load level of electrical power to be wirelessly transmitted through a wireless communication signal transmitted by a vehicle within a WPT space of any one of said plurality of point-of-load converters.

9. The apparatus of claim 6, wherein each of said at least one power transmission circuit comprises a series connection of an electronically controlled switch, a primary capacitor, and a primary coil, wherein said output power controller controls switching on and off of said electronically controlled switch.

10. The apparatus of claim 9, wherein said at least one power transmission circuit is a plurality of power transmission circuits.

11. The apparatus of claim 1, wherein said plurality of primary coils are configured as a linear array installed on a roadside, a pathway, or in a facility, and said output power controller controls switching on and off of AC current through said plurality of primary coils.

12. The apparatus of claim 11, wherein said output power controller causes a position of a turned-on primary coil to move at a substantially same velocity as a velocity that moves along said linear array, and turns off electrical current through primary coils that do not magnetically couple with a receiver coil of said vehicle.

13. A method for wireless power transfer comprising:

providing a wireless power transfer apparatus comprising an active front end unit configured to provide a unipolar output voltage;

a buck-boost converter configured to receive said unipolar output voltage and to generate a DC supply voltage to at least one DC power transmission cable; and

at least one point-of-load converter, each comprising a high frequency alternating current (AC) current generation circuit that is connected to one of said at least one DC power transmission cable and is configured to provide AC current through at least one power transmission circuit, wherein each of said at least one power transmission circuit comprises a primary coil for wireless power transfer;

determining a load level of electrical power to be wirelessly transmitted; and

controlling an output power level provided by said DC supply voltage to said at least one DC power transmission cable such that said output power level is proportional to said determined load level of electrical power to be wirelessly transmitted.

14. The method of claim 13, further comprising maintaining said DC supply voltage substantially constant irrespective of variations in said output power level.

15. The method of claim 13, wherein said at least one point-of-load converter is a plurality of point-of-load converters.

16. The method of claim 15, further comprising:

detecting presence or absence of a vehicle within a wireless power transfer (WPT) field of each of said point-of-load converters; and

switching on only a subset of said plurality of point-of-load converters having a vehicle within a wireless power transfer (WPT) field thereof, while switching off a complementary set of said subset.

17. The method of claim 15, further comprising identifying an incremental load level of electrical power to be wirelessly transmitted through a wireless communication signal transmitted by a vehicle within a WPT space of any one of said plurality of point-of-load converters.

18. The method of claim 15, wherein each of said at least one power transmission circuit comprises a series connection of an electronically controlled switch, a primary capacitor, and a primary coil, and said method further comprises controlling switching on and off of said electronically controlled switch.

19. The method of claim 13, further comprising:

providing said plurality of primary coils as a linear array installed on a roadside, a pathway, or in a facility; and

controlling switching on and off of AC current through said plurality of primary coils.

20. The method of claim 19, further comprising:

moving a position of a turned-on primary coil at a substantially same velocity as a velocity that moves along said linear array; and

turning off electrical current through primary coils that do not magnetically couple with a receiver coil of said vehicle.