CONTACTLESS POWER RECEIVER AND METHOD OF OPERATION

• US 20110090723A1
• Filed: 07/07/2009
• Published: 04/21/2011
• Est. Priority Date: 07/07/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: PowerbyProxi Limited (Apple Inc.)
• Inventors: Bhargava, Kunal, Si, Ping, Hu, Patrick Aiguo, Mishriki, Fady
• Granted Patent: US 9,124,113 B2
• Time in Patent Office: Days
• US Class Current: 363/74
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type

Abstract

A contactless power receiver is provided with a dynamically tuned pick up coil. The power transfer capacity of this power receiver is dynamically tuned using semiconductor devices that are operated in linear mode over part of their operation. The semiconductor devices are driven by a controller that is configured to implement a range of control strategies depending on system requirements. The semiconductor device may be used by itself or in conjunction with reactive elements to dynamically tune the pick up coil. In some implementations the contactless power receiver maybe configured to work with a consumer electronic or a wireless sensor device. The contactless power receiver can be integrated with the energy storage component of the device to provide a retrofit solution for existing products. The device can then be placed in vicinity of a planar magnetic field generated by a charging pad.

Claims

1. A contactless power receiver suitable for use in a near field inductively coupled power transfer system including:

a. a pick up coil;

b. one or more semiconductor devices for controlling current flow through the pick up coil; and

c. a control circuit which drives at least one semiconductor device in linear mode over at least part of its range of operation to tune the power receiver based on the output of the contactless power receiver.

2. The power receiver as claimed in claim 1 wherein the control circuit drives the one or more semiconductor devices to achieve essentially pure resistive tuning of the power receiver.

3. The power receiver as claimed in claim 1 wherein the control circuit drives one or more semiconductor devices in association with a capacitor resulting in capacitive tuning of the power receiver.

4. The power receiver as claimed in claim 1 wherein the control circuit drives one or more semiconductor devices in association with an inductor resulting in inductive tuning of the power receiver.

5. The power receiver as claimed in claim 1 wherein the control circuit drives one or more semiconductor devices in association with a capacitor and inductor resulting in hybrid tuning of the power receiver.

6. The power receiver as claimed in claim 1 wherein a plurality of semiconductor devices are used in parallel to tune the power receiver.

7. The power receiver as claimed in claim 1 wherein the control circuit includes at least one of a comparator, an operational amplifier, a microcontroller, a microcontroller with a look up table and a gate array logic device.

8. The power receiver as claimed in claim 1 wherein the power receiver is integrated with an energy storage device.

9. The power receiver of claim 1 wherein the power receiver is incorporated into an electronic device.

10. The power receiver as claimed in claim 1 wherein the one or more semiconductor devices and control circuit are incorporated into an integrated circuit.

17. A system for use with electronic devices including

a. a power transmitter including a drive circuit energizing a coil generating a magnetic field;

and

b. a power receiver as claimed in claim 1 wherein the power receiver is connected to an electronic device either through an energy storage device or directly.

18. The system as claimed in claim 17 wherein the electronic device is a consumer electronic device.

19. The system as claimed in claim 17 wherein the contactless power receiver is placed in a planar magnetic field generated by a charging pad.

11. In a contactless power system suitable for use in a near field inductively coupled power transfer system in which a power transmitter transmits power via a magnetic field to a pick up coil of a power receiver, a method of tuning the power receiver over at least part of its range of operation by operating a semiconductor device of the power receiver in linear mode to vary the resistance applied across the pick-up coil.

12. A method as claimed in claim 11 wherein a plurality of semiconductor devices are operated in linear mode to vary the resistance applied across the pick up coil.

13. A method as claimed in claim 11 wherein a plurality of semiconductor devices are provided in parallel with the pick up coil and one or more of the semiconductor devices is modulated in linear mode for fine tuning.

14. A method as claimed in claim 13 wherein one or more of the semiconductor devices operates in switch mode.

15. A method as claimed in claim 13 wherein one or more of the semiconductor devices operates in full conduction mode.

16. The method as claimed in claim 11 wherein control strategies used to tune the power receiver include one of a Schmitt trigger, proportional control, integral control and differential control.

20. A contactless power receiver suitable for use in a near field inductively coupled power transfer system including:

a. pick up coil inputs;

b. one or more semiconductor devices connected to the pick up coil inputs; and

c. a control circuit which when in use with a pick up coil connected to the pick up coil inputs drives at least one semiconductor device in linear mode over at least part of its range of operation to tune the power receiver based on the output of the contactless power receiver.