Method and system for wireless power transfer calibration

• US 9,667,322 B2
• Filed: 02/06/2013
• Issued: 05/30/2017
• Est. Priority Date: 12/28/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Walley, John
• Primary Examiner(s): Chiang, Jack
• Assistant Examiner(s): Bowers, Brandon
• Application Number:
  US13/760,924
• Publication Number:
  US 20140184150A1
• Time in Patent Office: 1,574 Days
• Field of Search: 320108
• 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 send or receive wireless power transfer signals, the coil module including a coil circuit;

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 in response to the tuning observer module detecting an out-of-tune state in order to provide the tuned state,

wherein the resonance controller module is further configured to determine whether a load of a recipient device is known, and in response to a determination that the load of the recipient device is not known, select the at least one parameter to be an adjustable parameter of the coil circuit, and in response to a determination that the load of the recipient device is known, select the at least one parameter to be a frequency of an input signal input to the coil module.

2. The wireless power transfer device of claim 1, wherein the coil circuit includes 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 circuit.

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 tuning capacitor being connected to a node between the first capacitor and the first inductor of the coil circuit.

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 tune the wireless power transfer device by adjusting a duty cycle of the control transistor.

12. A wireless power transfer device, comprising:

a coil module configured to send or 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 in response to the tuning observer module detecting an out-of-tune state in order to provide the tuned state,

wherein the coil module includes a coil circuit having a first resistor, a first capacitor, and a first inductor connected in series, the first inductor including 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 tune the wireless power transfer device by turning the control transistor on or off.

13. A wireless power transfer device, comprising:

a coil module configured to send wireless power transfer signals;

a system monitor module configured to detect an absence of a calibration-prohibitive event;

a tuning observer module configured to, in response to the detection of the absence of the calibration-prohibitive event, 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, in response to the tuning observer module detecting the out-of-tune state, adjust at least one parameter of the coil module in order to produce the tuned state,

wherein the resonance controller module is further configured to determine whether a load of a recipient device is known, and in response to a determination that the load of the recipient device is not known, select the at least one parameter to be an adjustable parameter of the coil module, and in response to a determination that the load of the recipient device is known, select the at least one parameter to be a frequency of an input signal input to the coil module.

14. The wireless power transfer device of claim 13,

wherein the coil module includes a resistor, and

wherein the tuning observer module detects the tuning state of the wireless power transfer device by measuring a current passing through the resistor and comparing the current to a predetermined threshold.

15. The wireless power transfer device of claim 13,

wherein the coil module includes a capacitor, and

wherein the tuning observer module detects the tuning state of the wireless power transfer device by measuring a voltage across the capacitor and comparing the voltage to a predetermined threshold.

16. The wireless power transfer device of claim 13,

wherein the coil module includes a resistor and a capacitor connected in series, and

wherein the tuning observer module is configured to measure a voltage across the capacitor and a current passing through the resistor.

17. The wireless power transfer device of claim 16, wherein the tuning observer module detects the tuning state of the wireless power transfer device based on a phase difference between the voltage and the current.

18. The wireless power transfer device of claim 17, wherein the tuning observer module detects the tuned state when the phase difference is within a predetermined window of zero degrees, and

wherein the tuning observer module detects the out-of-tune state when the phase difference is outside the predetermined window.

19. The wireless power transfer device of claim 13, wherein the resonance controller module is configured to perform a first calibration technique when the load is known and perform a second calibration technique when the load is unknown,

wherein the first calibration technique includes adjusting the frequency of the input signal and measuring a response in at least one circuit component.

20. The wireless power transfer device of claim 19, wherein, as part of the first calibration technique, the response is measured by measuring a current passing through a resistor of the resonance controller module.