Wireless power charging using point of load controlled high frequency power converters

• US 9,156,364 B2
• Filed: 01/11/2013
• Issued: 10/13/2015
• Est. Priority Date: 02/14/2012
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Miller, John M., Campbell, Steven L., Chambon, Paul H., Seiber, Larry E., White, Clifford P.
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): TRAN, THAI H
• Application Number:
  US13/739,198
• Publication Number:
  US 20130214591A1
• Time in Patent Office: 1,005 Days
• Field of Search: 307/104, 307/9.1
• US Class Current: 1/1
• 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 a plurality of DC power transmission cables;

an output power controller configured to control an output power level provided by said DC supply voltage to said plurality of DC power transmission cables; and

a plurality of point-of-load converters, each of the plurality of point-of-load converters comprises a high frequency alternating current (AC) current generation circuit that is respectively connected to one of said plurality of 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, the output power controller being further configured to control the AC current provided by each of the plurality of point-of-load converters based on a determined load level of electrical power to be wirelessly transmitted from the at least one power transmission circuit in each of the respective point-of-load converters, wherein the output power level provided by said DC supply voltage is determined based on an expected power demand of all of the plurality of point-of-load converters.

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 direct proportion to said expected power demand of all of the plurality of point-of-load converters.

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 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.

7. The apparatus of claim 1, 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.

8. The apparatus of claim 1, wherein said primary coil in each of the plurality of point-of-load converters are configured as a linear array installed on a roadway, a pathway, or in a facility, and said output power controller controls switching on and off of AC current through said primary coil in each of the plurality of point-of-load converters.

9. The apparatus of claim 8, 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.

10. The apparatus of claim 7, wherein said at least one power transmission circuit is a plurality of power transmission circuits and wherein said output power controller causes a position of a turned-on primary coil of the plurality of coils in each of the point-of-load converters to move at a substantially same velocity as a velocity that moves along said linear array, and turns off electrical current through primary coils of the plurality of coils in each of the point-of-load converters that do not magnetically couple with a receiver coil of said vehicle.

11. The apparatus of claim 1, further comprising a communication device configured to receive information regarding a battery in a vehicle to be charged.

12. The apparatus of claim 11, wherein the output power controller determines the load level of electrical power to be wirelessly transmitted for each of the plurality of point-of-load converters is based on the received information.

13. The apparatus of claim 12, wherein the output power controller controls a duty cycle of the high frequency alternating current (AC) current generation circuit for each of the plurality of point-of-load converters or a frequency offset for the AC current generated by the high frequency alternating current (AC) current generation circuit for each of the plurality of point-of-load converters based on the determined load level.

14. 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 a plurality of DC power transmission cables; and

a plurality of point-of-load converter, of the plurality of point-of-load converters comprises a high frequency alternating current (AC) current generation circuit that is connected to a respective one of said plurality of DC power transmission cables 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 an expected power demand of all of said plurality of point-of-load converters;

determining a load level of electrical power to be wirelessly transmitted from the at least one power transmission circuit in each of the respective point-of load converters; and

controlling an output power level provided by said DC supply voltage to said plurality of DC power transmission cables such that said output power level is proportional to said determined expected power demand of all of the plurality of point-of-load converters; and

controlling the AC current provided by each of the plurality of point-of-load converters based on the determined load level of electrical power to be wirelessly transmitted from the at least one power transmission circuit in each of the respective point-of-load converters.

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

16. The method of claim 14, further comprising:

detecting presence or absence of a vehicle within a wireless power transfer (WPT) field of each of said plurality of 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 14, 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.

18. The method of claim 14, further comprising:

providing said primary coil in each of the plurality of point-of-load converters as a linear array installed on a roadway, a pathway, or in a facility; and

controlling switching on and off of AC current through said primary coil in each of the plurality of point-of-load converters.

19. The method of claim 18, 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.

20. The method of claim 14, further comprising:

receiving information regarding a battery in a vehicle to be charged.

21. The method of claim 20, wherein the load level of electrical power to be wirelessly transmitted for each of the plurality of point-of-load converters is determined based on the received information.