RESONANCE DETECTION AND CONTROL WITHIN A WIRELESS POWER SYSTEM

• US 20110278945A1
• Filed: 11/11/2010
• Published: 11/17/2011
• Est. Priority Date: 05/13/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wheatley, Charles E. III, Low, Zhen Ning
• Granted Patent: US 9,479,225 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• 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 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• 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 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

Exemplary embodiments are directed to resonant frequency tuning. A device may include a coil for transmitting wireless power. The device may further include a transmit an element to selectively modify a resonant frequency of the transmitter according to at least one inserting the element into the transmit coil and inductively coupling the element to the transmit coil

Claims

1. A transmitter, comprising:

a transmit coil configured to transmit wireless power; and

an element to selectively modify a resonant frequency of the transmitter according to at least one of inserting the element into the transmit coil and inductively coupling the element to the transmit coil.

2. The transmitter of claim 1, the at least element comprising one of a parasitic antenna and a reactive element.

3. The transmitter of claim 2, the at least one reactive element comprising a capacitor.

4. The transmitter of claim 2, further comprising at least one switching element configured to one of switch the reactive element into the transmit coil and close a loop of the parasitic coil.

5. The transmitter of claim 4, the at least one switching element in series with the transmit coil and in parallel with the at least one reactive element.

6. The transmitter of claim 4, the at least one switching element comprising a plurality of transistors, each transistor of the plurality of transistors having a drain coupled to the at least one reactive element.

7. The transmitter of claim 4, the parasitic coil comprising an ideal inductor and a parasitic resistor and configured to be tuned by a capacitor, the switching element coupled between the capacitor and a ground voltage.

8. The transmitter of claim 2, the parasitic coil further comprising at least one reactive element in parallel with the switching element.

9. The transmitter of claim 8, the at least one reactive element configured to cause the parasitic coil to self resonate.

10. A method, comprising:

wireless transmitting energy with a transmitter; and

tuning a resonant frequency of the transmitter by at least one of switching at least one reactive element into a transmitting coil of the transmitter and inductively coupling the transmitting coil with a parasitic coil of the transmitter.

11. The method of claim 10, switching at least one reactive element into a transmitting coil comprising opening a switching element in parallel with the at least one reactive element.

12. The method of claim 10, switching at least one reactive element into a transmitting coil comprising opening a plurality of transistors in parallel with the at least one reactive element.

13. The method of claim 10, further comprising:

sensing a baseline current at the transmitter;

sensing another current at the transmitter while at least one wireless power receiver is within a charging region of the transmitter; and

comparing the baseline current with the another current prior to switching at least one reactive element into the transmitting coil.

14. The method of claim 10, inductively coupling comprising inductively coupling the transmitting coil with the parasitic coil comprising a resistor coupled between a capacitor and an inductor.

15. The method of claim 10, inductively coupling comprising closing a switching element to form a loop on the parasitic coil to reduce a self-inductance of the transmitting coil.

16. The method of claim 10, inductively coupling further comprising switching at least one reactive element into the parasitic coil to cause the parasitic coil to resonate.

17. A device, comprising:

means for wireless transmitting energy with a transmitter; and

means for tuning a resonant frequency of the transmitter by at least one of switching at least one reactive element into a transmitting coil of the transmitter and inductively coupling the transmitting coil with a parasitic coil of the transmitter.

18. The device of claim 17, further comprising means for opening a switching element in parallel with the at least one reactive element to tune the resonant frequency of the transmitter.

19. The device of claim 17, further comprising:

means for sensing a baseline current at the transmitter;

means for sensing another current at the transmitter while at least one wireless power receiver is within a charging region of the transmitter; and

means for comparing the baseline current with the another current prior to switching at least one reactive element into a transmitting coil.

20. The device of claim 17, further comprising means for closing a switching element to form a loop on the parasitic coil to reduce a self-inductance of the transmitting coil.