Methods and systems for rapid wireless charging where the low state of charge (SOC) temperature dependent charging current and low SOC temperature limit are higher than the high SOC temperature dependent charging current and high SOC temperature limit

• US 9,356,461 B2
• Filed: 09/25/2012
• Issued: 05/31/2016
• Est. Priority Date: 09/25/2012
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Inventors: Howard, Jason N., Hanley, Michael G.
• Primary Examiner(s): Grant, Robert
• Assistant Examiner(s): TRISCHLER, JOHN T
• Application Number:
  US13/625,976
• Publication Number:
  US 20140084856A1
• Time in Patent Office: 1,344 Days
• Field of Search: 320/134, 320/138, 320/162, 320/108, 320/150, 320/153
• US Class Current: 1/1
• CPC Class Codes: H01F 7/0247 Orientating, locating, transporting arrangements
• CPC Class Codes: H01M 10/443 in response to temperature
• 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 7/007 Regulation of charging or discharging current or voltage
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/00716 in response to integrated charge or discharge current
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A system and method for wireless charging are provided. A control circuit charges one or more cells in a secondary wireless charging circuit that receives power wirelessly from a primary. The control circuit determines the state of charge and temperature of the cells. The control circuit then calculates a current limit as a function of a combination of the state of charge, input voltage to the control circuit for the wireless controller, FET power dissipation and the temperature and adjusts a wireless power control device in the secondary such that its current limit is set to the state of charge current limit. Different temperature limits can be used for different states of charge such that the cells can be charged at higher temperatures at low states of charge than at higher states of charge.

Claims

1. A method of adjusting a wireless power control device of a secondary of a wireless charging circuit for one or more cells configured to be charged via a primary side of the wireless charging circuit, the method comprising:

in a control circuit operable with the one or more cells, determining a state of charge of the one or more cells, a temperature of the one or more cells, and a voltage received from the secondary of the wireless charging circuit;

in response to the state of charge being below a predetermined state of charge threshold;

calculating, in the control circuit, a low state of charge current limit that is determined based upon the state of charge, the temperature of the one or more cells, and the voltage received from the secondary side of the wireless charging circuit;

delivering, to the wireless power control device, a current adjustment input comprising the low state of charge current limit;

monitoring the temperature of the one or more cells to identify if the temperature of the one or more cells is remaining below a predetermined low state of charge cell temperature threshold;

recalculating the low state of charge current limit to reduce the low state of charge current limit as a function of one or more increases in the temperature of the one or more cells;

prior to the temperature of the one or more cells breaching the predetermined low state of charge cell temperature threshold, reducing the low state of charge current limit using the recalculated low state of charge current limit effective to prevent the temperature of the one or more cells from breaching the predetermined low state of charge cell temperature threshold;

transitioning to an operating state associated with a high state of charge; and

responsive to transitioning to the operating state associated with the high state of charge, comparing the temperature of the one or more cells to a predetermined high state of charge cell temperature threshold instead of the predetermined low state of charge cell temperature threshold effective to prevent the temperature of the one or more cells from exceeding the predetermined high state of charge cell temperature threshold; and

in response to the state of charge being above the predetermined state of charge threshold;

calculating, in the control circuit, a high state of charge current limit that is less than the low state of charge current limit, the high state of charge current limit based upon the state of charge, the temperature of the one or more cells, and the voltage received from the secondary side of the wireless charging circuit; and

delivering a current adjustment input comprising the high state of charge current limit to the wireless power control device of the wireless charging circuit effective to;

reduce the voltage received from the secondary side of the wireless charging circuit;

maintain the temperature of the one or more cells below the predetermined high state of charge cell temperature threshold; and

maintain a constant current operating mode in one or more pass elements coupled serially with the one or more cells.

2. The method of claim 1, further comprising wirelessly communicating power information, from the secondary side to the primary side, using one or more error signals.

3. The method of claim 1, further comprising:

in response to the state of charge being above the predetermined state of charge threshold;

determining an amount of power dissipation in one or more serial pass elements; and

responsive to the amount of power dissipation exceeding a predetermined power dissipation threshold;

decrementing the high state of charge current limit effective to generate a new high state of charge current limit; and

delivering, to the wireless power control unit, a current limit adjustment input based on the new high state of charge current limit.

4. The method of claim 1, wherein calculating the high state of charge current limit further comprises:

responsive to one or more increases in the temperature of the one or more cells, recalculating the high state of charge current limit based on the one or more increases in the temperature of the one or more cells effective to reduce the high state of charge current limit.

5. The method of claim 4, wherein, responsive to the recalculating resulting in a reduced high state of charge current limit, delivering, to the wireless power control device, a current limit adjustment input based on the reduced high state of charge current limit.

6. A system for wireless charging, comprising:

one or more cells;

one or more pass elements coupled serially with the one or more cells;

a control circuit operable with the one or more pass elements;

a temperature sensor, operable with the control circuit, and configured to sense a temperature of the one or more cells; and

a secondary side of a wireless power transfer system configured to deliver power to the one or more cells, the secondary side comprising a wireless power control device,

the control circuit further configured to;

determine a state of charge of the one or more cells;

determine, with the temperature sensor, the temperature of the one or more cells;

responsive to determining the state of charge being below a predetermined state of charge threshold;

calculate a low state of charge current limit based, at least in part, on a combination of the state of charge and the temperature of the one or more cells;

monitor a charging current associated with charging the one or more cells to identify if the charging current is remaining below the low state of charge current limit;

monitor the temperature of the one or more cells to identify if the temperature of the one or more cells is remaining below a predetermined low state of charge cell temperature threshold;

recalculate the low state of charge current limit to reduce the low state of charge current limit based upon one or more increases in the temperature of the one or more cells;

prior to the temperature of the one or more cells breaching the predetermined low state of charge cell temperature threshold, reduce the low state of charge current limit effective to prevent the temperature of the one or more cells from breaching the predetermined low state of charge cell temperature threshold; and

transition to an operating state associated with a high state of charge at least by comparing the temperature of the one or more cells to a predetermined high state of charge cell temperature threshold instead of the predetermined low state of charge cell temperature threshold effective to prevent the temperature of the one or more cells from exceeding the predetermined high state of charge cell temperature threshold; and

responsive to the state of charge being above the predetermined state of charge threshold;

calculate a high state of charge current limit as a function of a combination of the state of charge and the temperature of the one or more cells;

monitor the temperature of the one or more cells to identify if the temperature of the one or more cells is remaining below a predetermined high state of charge temperature threshold; and

adjust the high state of charge current limit based upon one or more increases in the temperature of the one or more cells.

7. The system of claim 6, wherein the low state of charge current limit is higher than the high state of charge current limit.

8. The system of claim 6, wherein the predetermined low state of charge temperature threshold is higher than the predetermined high state of charge temperature threshold.

9. The system of claim 6, wherein the control circuit is further configured to:

determine an amount of power dissipation in at least one pass element of the one or more pass elements; and

responsive to the state of charge being above the predetermined state of charge threshold and the amount of power dissipation being above a predetermined power dissipation threshold, reduce the high state of charge current limit.

10. The system of claim 6, wherein the control circuit is configured to wirelessly communicate information to a primary side of the wireless power transfer system, the information comprising at least one of:

power adjustment data;

authentication data;

control data;

or

power usage data.

11. The system of claim 6, wherein the control circuit is configured to adjust the wireless power control device by delivering data comprising the high state of charge current limit or the low state of charge current limit to an input of the wireless power control device.

12. A method of wirelessly charging one or more cells of a battery, the method comprising:

at a secondary side of a wireless charging system, in a control circuit operable with the one or more cells, determining a state of charge of the one or more cells and a temperature of the one or more cells;

in response to the state of charge being greater than a state of charge threshold, at the control circuit;

calculating a high state of charge current limit as a function of the state of charge and the temperature of the one or more cells; and

adjusting a current limit of a wireless power control device to the high state of charge current limit; and

in response to the state of charge being less than the state of charge threshold;

calculating, as a function of the state of charge and the temperature of the one or more cells, a low state of charge current limit that is higher than the high state of charge current limit;

adjusting the current limit of the wireless power control device to the low state of charge current limit;

monitoring the temperature of the one or more cells to identify if the temperature of the one or more cells is remaining below a predetermined low state of charge cell temperature threshold;

recalculating the low state of charge current limit to reduce the low state of charge current limit as a function of one or more increases in the temperature of the one or more cells;

prior to the temperature of the one or more cells breaching the predetermined low state of charge cell temperature threshold, reducing the low state of charge current limit effective to prevent the temperature of the one or more cells from breaching the predetermined low state of charge cell temperature threshold;

transitioning to an operating state associated with a high state of charge; and

responsive to transitioning to the operating state associated with the high state of charge, comparing the temperature of the one or more cells to a predetermined high state of charge cell temperature threshold instead of the predetermined low state of charge cell temperature threshold effective to prevent the temperature of the one or more cells from exceeding the predetermined high state of charge cell temperature threshold.

13. The method of claim 12, wherein the predetermined high state of charge cell temperature threshold is 5 degrees centigrade and the predetermined low state of charge cell temperature threshold is 60 degrees centigrade.

14. The method of claim 12, wherein the high state of charge current limit is configured to prevent the temperature of the one or more cells from exceeding the predetermined high state of charge cell temperature threshold by limiting a current charging the one or more cells.

15. The method of claim 14 further comprising:

wirelessly communicating power information, from the secondary side to a primary side of the wireless charging system, using one or more error signals.

16. The method of claim 12, further comprising reducing the high state of charge current limit when the temperature of the one or more cells rises.

17. The method of claim 16, further comprising:

determining an amount of power dissipation in at least one pass element coupled serially with the one or more cells; and

responsive to the amount of power dissipation exceeding a predetermined power dissipation threshold, reducing the high state of charge current limit to permit the at least one pass element to operate in a constant current mode while maintaining the temperature of the one or more cells below the predetermined high state of charge temperature threshold.

18. The method of claim 17, further comprising:

measuring, with a current sensor operable with the control circuit, a current charging the one or more cells;

comparing the current to a minimum current threshold; and

responsive to the current charging the one or more cells dropping below the minimum current threshold, adjusting the high state of charge current limit effective to operate the at least one pass element in a constant voltage mode.