Method and System for Wireless Power Transfer Calibration

• US 20140184150A1
• Filed: 02/06/2013
• Published: 07/03/2014
• Est. Priority Date: 12/28/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: WALLEY, John
• Granted Patent: US 9,667,322 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 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

In a WPT system, varying parameters, such as coupling coefficient, may cause the system to fall out of resonance and/or tuning. By monitoring one or more signals within a coil module of the WPT device, this detuning can be detected. Moreover, the WPT system can retune itself by modifying one or more parameters in a transmitting WPT device and/or a receiving WPT device. For example, coil circuits in the transmitting and/or receiving WPT devices can be configured to allow for adjusting of effective capacitance, effective inductance, load resistance, and/or load inductance. In addition, frequency can be modified to permit adjusting power transfer efficiency.

Claims

1. A wireless power transfer device, comprising:

a coil module configured to at least one of send and receive wireless power transfer signals;

a tuning observer module configured to detect a tuning state of the wireless power transfer device, the tuning state being one of a tuned state or an out-of-tune state; and

a resonance controller module configured to adjust at least one parameter of the coil module when the tuning observer module detects an out-of-tune state in order to provide the tuned state.

2. The wireless power transfer device of claim 1, wherein the coil module includes a coil circuit having a first resistor, a first capacitor, and a first inductor connected in series.

3. The wireless power transfer device of claim 2, wherein the tuning observer module is configured to detect the tuning state based on a current passing through the first resistor.

4. The wireless power transfer device of claim 2, wherein the tuning observer module includes a voltage detector connected at a node between the first capacitor and the first inductor, and

wherein the tuning observer module detects the tuning state based on a voltage detected by the voltage detector.

5. The wireless power transfer device of claim 2, wherein the tuning observer module includes a second inductor, a second resistor, and a voltage detector connected in parallel.

6. The wireless power transfer device of claim 5, wherein the second inductor of the tuning observer module is inductively coupled to the first inductor of the coil module.

7. The wireless power transfer device of claim 6, wherein the tuning observer module detects the tuning state based on a voltage detected by the voltage detector.

8. The wireless power transfer device of claim 2, wherein the resonance controller module includes a tuning capacitor and a control transistor connected in series, the timing capacitor being connected to a node between the first capacitor and the first inductor of the coil module.

9. The wireless power transfer device of claim 8, wherein the resonance controller module is configured to tune the wireless power transfer device by adjusting a duty cycle of the control transistor.

10. The wireless power transfer device of claim 2, wherein the resonance controller module includes a tuning inductor serially connected to the first inductor, and a control transistor connected to a node between the first inductor and the tuning inductor.

11. The wireless power transfer device of claim 10, wherein the resonance controller module is configured to time the wireless power transfer device by adjusting a duty cycle of the control transistor.

12. The wireless power transfer device of claim 2, wherein the first inductor includes a plurality of windings,

wherein the resonance controller module includes a control transistor connected to the first inductor at a node so as to separate the plurality of windings into a first number of windings and a second number of windings, and

wherein the resonance controller is configured to time the wireless power transfer device by turning the control transistor on or off.

13. A method of performing a diagnostic service during wireless power transfer, the method comprising:

detecting, by a wireless power transfer station, a wirelessly-chargeable device in close proximity of the wireless power transfer station, the wirelessly-chargeable device having a known geometric location relative to the wireless power transfer station;

determining a coupling coefficient between a radiating coil of the wireless power transfer station and a receiving coil of the wirelessly-chargeable device;

comparing the determined coupling coefficient to an expected coupling coefficient and declaring a fault if the determined coupling coefficient is below the expected coupling coefficient by a threshold amount; and

communicating the fault to the wireless-chargeable device.

14. The method of claim 13, wherein the communicating is performed using in-band wireless power transfer communications.

15. The method of claim 13, wherein the communicating is performed using a type of out-of-band communications, including one of Bluetooth, NFC, and WiFi communications systems.

16. The method of claim 13, further comprising communicating the fault to one of a manufacturer or a service provider associated with the wirelessly-chargeable device using out-of-band communications.

17. The method of claim 13, further comprising performing a diagnostic on an out-of-band communications link between the wireless power transfer station and the wirelessly-chargeable device, the diagnostic of the out-of-band communications link based on a received signal strength associated with the out-of-band communications link.

18. The method of claim 17, further comprising communicating a second fault to the wirelessly-chargeable device if the diagnostic on the out-of-band communications link fails.

19. A method of performing a diagnostic of a second wireless power transfer device by a first wireless power transfer device, the method comprising:

calculating an expected value of a transmission parameter of the second power transfer device based on a known geometry of the second power transfer device relative to the first wireless power transfer device;

detecting an actual value of the transmission parameter; and

determining that the actual value of the transmission parameter differs from the expected value of the transmission parameter by a threshold value, indicative of an error.

20. The method of claim 19, further comprising notifying the second wireless transfer device of the error.