Power Management for Inductive Charging Systems

• US 20150061588A1
• Filed: 08/26/2014
• Published: 03/05/2015
• Est. Priority Date: 09/03/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Alves, Jeffrey M., Moyer, Todd K., Bossetti, Chad
• Granted Patent: US 9,847,666 B2
• Time in Patent Office: Days
• US Class Current: 320/108
• CPC Class Codes: H02J 50/10 using inductive coupling
• 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 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0032 disconnection of loads if battery is not under charge, e.g. in vehicle if engine is not running
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Power management and power transfer systems within the transmit and receive portions of an inductive charging system. An inductive charging system may include an inductive charging station to transmit power and a portable electronic device to receive power. Embodiments may take the form of power transfer systems within an inductive charging station including load-based transmit frequency adjustments. Embodiments may also take the form of power management systems within portable electronic devices which conserve power by disconnecting circuits from ground when those circuits are in an idle state.

Claims

1. An adaptive power control system for an electromagnetic induction power transfer apparatus comprising:

a wireless signal receiver;

an alternating current power supply having an operating frequency;

a power-transmitting inductor coupled to the power supply; and

a current monitor coupled to the power-transmitting inductor;

wherein;

the current monitor determines a current load of the power-transmitting inductor;

the operating frequency of the power supply is modified in response to the current load; and

the operating frequency of the power supply is modified in response to a signal received from the wireless signal receiver.

2. The adaptive power control system of claim 1, wherein the power supply is turned off in response to a current load below a current load minimum threshold.

3. The adaptive power control system of claim 1, wherein modification of the operating frequency of the power supply in response to the current load is substantially simultaneous with changes in current load.

4. The adaptive power control system of claim 1, wherein the signal received from the wireless signal receiver is a feedback signal sent at an interval from a portable electronic device inductively proximate the power-transmitting inductor.

5. The adaptive power control system of claim 4, wherein modification of the operating frequency of the power supply in response to the feedback signal overrides modification of the operating frequency of the power supply in response to the current load.

6. The adaptive power control system of claim 5, wherein once a modification of the operating frequency of the power supply in response to the current load is overridden by a modification of the operating frequency of the power supply in response to the feedback signal, subsequent modification of the operating frequency of the power supply in response to a subsequent change in current load is ignored for a select timeout period.

7. The adaptive power control system of claim 6, wherein the select timeout period is less than the interval of the feedback signal.

8. The adaptive power control system of claim 6, wherein the select timeout period is greater than the interval of the feedback signal.

9. The adaptive power control system of claim 4, wherein the portable electronic device includes a surge protection circuit operative to prevent damage to the portable electronic device as a result of an increase in power transmitted by the power-transmitting inductor.

10. The adaptive power control system of claim 9, wherein the surge protection circuit comprises a capacitor.

11. The adaptive power control system of claim 1, wherein the modification of the operating frequency of the power supply in response to a change in current load change is limited to a selected maximum.

12. An adaptive power system for a portable electronic device, comprising:

a battery;

a power-receiving inductor having at least an idle state and a receiving state;

a power conversion controller coupled to the power receiving inductor;

a charge monitor coupled to the battery and the power conversion controller; and

a ground connection controller;

wherein;

in the idle state, the ground connection controller disconnects the charge monitor from ground; and

in the receiving state, the ground connection controller connects the charge monitor to ground.

13. The adaptive power system of claim 12, further comprising a power conversion controller including a rectifier and voltage regulator.

14. The adaptive power system of claim 13, wherein the power conversion controller comprises a voltage comparator between the present voltage of the battery and the present voltage output from the voltage regulator.

15. The adaptive power system of claim 12, wherein the ground connection controller comprises a switch circuit for controlling an electrical connection to ground.

16. The adaptive power system of claim 13, wherein the power management controller comprises at least a charging state and a direct operation state.

17. The adaptive power system of claim 16, wherein the charging state comprises the power management controller coupling the power conversion controller to the battery.

18. The adaptive power system of claim 16, wherein the direct operation state comprises the power management controller coupling the power conversion controller to circuitry of the portable electronic device such that the portable electronic device may be operated without drawing power from the battery.

19. A method of controlling an inductive charging system within a portable electronic device having a battery, comprising:

determining whether the portable electronic device is inductively proximate a power transmitter;

providing a direct connection to ground of the inductive charging system in response to the determination that the portable electronic device is inductively proximate a power transmitter; and

removing a direct connection to ground of the inductive charging system in response to the determination that the portable electronic device is not inductively proximate a power transmitter.

20. The method of claim 19, wherein determining whether the portable electronic device is inductively proximate a power transmitter comprises monitoring a voltage across a power receiving inductor within the portable electronic device.

21. The method of claim 20, wherein providing a direct connection to ground comprises setting a ground connection controller to an on state.

22. The method of claim 21, wherein removing a direct connection to ground comprises setting the ground connection controller to an off state.

23. The method of claim 22, wherein the state of the ground connection controller is set by the voltage across the power receiving inductor.

24. The method of claim 23, wherein when the voltage across the power receiving inductor exceeds a select magnitude, the ground connection controller is set to an on state.

25. The method of claim 23, wherein when the voltage across the power receiving inductor is below the select magnitude, the ground connection controller is set to an off state.

26. A method of modifying power output of an electromagnetic induction power transfer apparatus comprising:

determining a current load on a power-transmitting inductor supplied with an alternating current at a frequency;

adjusting the frequency in response to the determined current load;

receiving a signal of power required; and

modifying the adjusted frequency in response to the received signal.

27. The method of claim 26, wherein adjusting the frequency in response to the current load comprises:

increasing the frequency to reduce the power output from the power-transmitting inductor; and

decreasing the frequency to increase the power output from the power-transmitting inductor.

28. The method of claim 26, wherein receiving a signal of power required comprises receiving a signal from a portable electronic device inductively proximate the power-transmitting inductor at an interval, the signal comprising the power requirements of the portable electronic device.

29. The method of claim 28, wherein modifying the adjusted frequency in response to the received signal comprises adjusting the frequency such that power transmitted to the portable electronic device matches the power requirements of the portable electronic device.

30. The method of claim 27, wherein adjusting the frequency in response to the current load is substantially simultaneous with changes in the current load.

31. The method of claim 30, wherein adjustments in the frequency made in response to the current load are limited to a select maximum.

32. The method of claim 30, wherein modification of the frequency in response to the received signal overrides modification of the frequency in response to the current load.

33. The method of claim 32, wherein once a modification of the frequency in response to the current load is overridden by a modification of the frequency in response to the received signal, a subsequent modification of the frequency in response to a subsequent change in current load is ignored for a select timeout period.