CHARGE CURRENT MONITORING OR CONTROL IN A RESONANCE-TUNED INDUCTIVE CHARGER

• US 20150249359A1
• Filed: 02/28/2014
• Published: 09/03/2015
• Est. Priority Date: 02/28/2014
• Status: Active Grant

• Current Assignee: L'Oreal SA
• Original Assignee: L'Oreal SA
• Inventors: Gunderson, David Allen
• Granted Patent: US 10,283,995 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 50/12 of the resonant type
• 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 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters

Abstract

A battery charger and methods for magnetically transferring power from a power source to a battery is disclosed. A driver circuit outputs a modulated signal having a duty cycle from the power source to a sender-side circuit and across a space to a receiver-side tuned circuit. A sender-side sensor is configured to sense a parameter of the sender-side tuned circuit. The controller modifies the first duty cycle of the modulated signal based on the sensed parameter. A receiver-side circuit capable of determining charge status of the receiver side is also disclosed.

Claims

1. A battery charger for magnetically transferring power from a power source to a battery, the battery charger comprising:

a driver circuit couplable to the power source, the driver circuit configured to output a modulated signal with energy from the power source, wherein the modulated signal has a duty cycle;

a sender-side tuned circuit magnetically couplable across a space to a receiver-side tuned circuit of a portable handheld electronic device, wherein the sender-side tuned circuit is configured to have a resonant frequency near or equal to the receiver-side tuned circuit;

a sender-side sensor configured to sense a parameter of the sender-side tuned circuit; and

a controller coupled to the driver circuit and to the sender-side sensor, wherein the controller is configured to;

cause the driver circuit to output a modulated signal at a first duty cycle and at a frequency near or equal to the resonance frequency of at least one of the sender-side tuned circuit and the receiver-side tuned circuit, and

modify the first duty cycle of the modulated signal based on the sensed parameter of the sender-side tuned circuit.

2. The battery charger of claim 1, wherein the sender-side sensor is configured to sense a voltage of the sender-side tuned circuit.

3. The battery charger of claim 2, wherein the sender-side tuned circuit includes an inductor and a capacitor, and wherein the sender-side sensor is configured to sense a voltage of the sender-side tuned circuit on the high side of the inductor.

4. The battery charger of claim 1, wherein the sender-side sensor is further configured to scale an input signal proportional to the high-side voltage so that the input signal is suitably compatible with the controller.

5. The battery charger of claim 3, wherein the sender-side sensor comprises a diode having a first terminal coupled to a high side of the inductor, wherein a second terminal of the diode is coupled to the controller through a low pass filter.

6. The battery charger of claim 1, wherein the controller is further configured to:

increase the duty cycle, if the sensed parameter is above a threshold value; and

decrease the duty cycle, if the sensed parameter is below the threshold value.

7. The battery charger of claim 1, wherein the sender-side circuit is configured to have a high-side voltage that is above a peak threshold voltage level, if the sender-side circuit and the receiver-side circuit are not inductively coupled to one another.

8. The battery charger of claim 7, wherein the controller is configured to enter an idle mode, if the high-side voltage of the first inductor is determined to be above a peak threshold voltage level.

9. A method of transferring power from a sender-side circuit to a receiver-side circuit to charge a battery on the receiver-side, the method comprising:

starting an energizing cycle by modulating a voltage provided by a power source through an inductor of the sender-side circuit, wherein the modulated voltage has a constant predetermined frequency and a first duty cycle;

determining a voltage level variable corresponding to a voltage sensed by a voltage sensor at a high-side of the sender-side inductor;

comparing the determined voltage level variable to a predetermined threshold voltage level; and

modifying the duty cycle of the modulated voltage based on the comparison of the determined voltage level variable to the predetermined threshold voltage level.

10. The method of claim 9, wherein the predetermined frequency of the modulated voltage corresponds to a resonant frequency of at least one of a sender-side circuit and a resonance frequency of the receiver-side circuit.

11. The method of claim 9, wherein said modifying the duty cycle of the modulated voltage includes:

decreasing the duty cycle if the determined voltage level of the high side of the sender-side inductor is greater than the predetermined threshold voltage level; and

increasing the duty cycle if the determined voltage level of the high side of the sender-side inductor is less than the predetermined threshold voltage level.

12. The method of claim 11, wherein said modifying the duty cycle of the modulated voltage further includes:

setting the duty cycle to a maximum duty cycle if the determined voltage level of the high side of the sender-side inductor is greater than the maximum duty cycle; and

setting the duty cycle to the minimum duty cycle if the determined voltage level of the high side of the sender-side inductor is less than the minimum duty cycle.

13. The method of claim 9, further comprising determining if the sender-side circuit and the receiver-side circuit are not inductively coupled to one another using the determined voltage level at the high side of the receiver-side inductor.

14. The method of claim 13, further comprising adjusting the duty cycle to correspond to an idle mode, if the sender-side circuit and the receiver-side circuit are not inductively coupled to one another.

15. A non-transitory computer readable storage medium having instructions included thereon, that in response to an execution by one or more computing device, cause the one or more computing devices to carry out the method of claim 9.

16. A non-transitory computer readable storage medium having instructions included thereon, that in response to an execution by one or more computing device, cause the one or more computing devices to carry out the method of claim 10.

17. A non-transitory computer readable storage medium having instructions included thereon, that in response to an execution by one or more computing device, cause the one or more computing devices to carry out the method of claim 11.

18. A non-transitory computer readable storage medium having instructions included thereon, that in response to an execution by one or more computing device, cause the one or more computing devices to carry out the method of claim 12.

19. A non-transitory computer readable storage medium having instructions included thereon, that in response to an execution by one or more computing device, cause the one or more computing devices to carry out the method of claim 13.

20. A non-transitory computer readable storage medium having instructions included thereon, that in response to an execution by one or more computing device, cause the one or more computing devices to carry out the method of claim 14.

21. A receiver-side charging circuit coupled to a portable device, the receiver-side circuit capable of determining charge status, the receiver-side charging circuit comprising:

a tuned circuit having a resonance frequency; and

a receiver-side sensor coupled to an input of a controller and configured to sense a parameter of the tuned circuit,

wherein the tuned circuit is couplable to a battery and inductively couplable across a space to a sender-side circuit having substantially similar resonance frequency, and

wherein the controller is configured to cause an indication that charging is not occurring if the sensed parameter is below a threshold level.

22. A receiver-side circuit coupled to a portable device of claim 21, wherein the indicating that charging is not occurring comprises turning on or off an LED.