US-12627177-B2 - Transmitter coil power foreign object detection

US12627177B2US 12627177 B2US12627177 B2US 12627177B2US-12627177-B2

Abstract

Systems, methods and apparatus for wireless charging are disclosed. A wireless charging device has a resonant circuit including one or more power transmitting coils in a charging surface of the charging device, a driver circuit configured to provide a charging current to the resonant circuit, and a controller. The controller is configured to determine an average transmitted power using samples of current and voltage captured from the resonant circuit, and determine that a foreign object is located on or near the charging surface when the average transmitted power exceeds a measurement of received power provided by a receiving device and parasitic losses associated with the wireless charging device. In one example, each sample of current is obtained by measuring a current flowing in the resonant circuit, and each of sample of voltage is obtained by measuring a voltage across the one or more power transmitting coils.

Inventors

Mohammad Ali Saket Tokaldani
Eric Heindel Goodchild

Assignees

AIRA, INC.

Dates

Publication Date: 20260512
Application Date: 20220812

Claims (13)

1 . A method for operating a wireless charging device, comprising: providing a charging current to a resonant circuit that includes one or more power transmitting coils in a charging surface of a wireless charging device; determining an average transmitted power using samples of current and voltage captured from the resonant circuit; determining that a foreign object is located on or near the charging surface when the average transmitted power exceeds a measurement of received power provided by a receiving device and parasitic losses associated with the wireless charging device; and capturing the samples of current and voltage in one or more sampling cycles having a period that spans a plurality of periods of a cycle of the charging current, wherein each sampling cycle includes a plurality of sampling points, wherein each of the plurality of sampling points occurs at a different phase of the cycle of the charging current than each of the other samples in the plurality of sampling points, wherein the one or more sampling cycles includes a first sampling cycle and a second sampling cycle, wherein a first sample of current is captured at a first sampling point in the first sampling cycle, and wherein a first sample of voltage is captured at a corresponding first sampling point in the second sampling cycle.
2 . The method of claim 1 , wherein each sample of current is obtained by measuring a current flowing in the resonant circuit, and each of sample of voltage is obtained by measuring a voltage across the one or more power transmitting coils.
3 . The method of claim 1 , wherein samples of current and voltage are captured simultaneously at each sampling point in the plurality of sampling points in a single sampling cycle.
4 . A method for operating a wireless charging device, comprising: providing a charging current to a resonant circuit that includes one or more power transmitting coils in a charging surface of a wireless charging device; determining an average transmitted power using samples of current and voltage captured from the resonant circuit; determining that a foreign object is located on or near the charging surface when the average transmitted power exceeds a measurement of received power provided by a receiving device and parasitic losses associated with the wireless charging device; providing a root clock signal having a root clock frequency; dividing the root clock frequency by a first integer to obtain a sampling clock frequency that determines frequency of a sampling cycle in which the samples of current and voltage captured from the resonant circuit; and dividing the root clock signal by a second integer to obtain a charging clock frequency that controls frequency of the charging current, wherein the first integer and the second integer have a largest common divisor of 1.
5 . The method of claim 1 , wherein the parasitic losses are attributable to metallic or magnetically permeable components of the wireless charging device.
6 . A charging device, comprising: a resonant circuit comprising one or more power transmitting coils in a charging surface of the charging device; a driver circuit configured to provide a charging current to the resonant circuit; and a controller configured to: determine an average transmitted power using samples of current and voltage captured from the resonant circuit; and determine that a foreign object is located on or near the charging surface when the average transmitted power exceeds a measurement of received power provided by a receiving device and parasitic losses associated with the charging device; and one or more analog-to-digital converters (ADC) configured to capture the samples of current and voltage based on one or more sampling cycles having a period that spans a plurality of periods of a cycle of the charging current, wherein each sampling cycle includes a plurality of sampling points, wherein each of the plurality of sampling points occurs at a different phase of the cycle of the charging current than each of the other samples in the plurality of sampling points, and wherein the one or more ADCs comprise a single ADC configured to: capture a first sample of current at a first sampling point in a first sampling cycle; and capture a first sample of voltage at a corresponding first sampling point in a second sampling cycle.
7 . The charging device of claim 6 , wherein each sample of current is obtained by measuring a current flowing in the resonant circuit, and each of sample of voltage is obtained by measuring a voltage across the one or more power transmitting coils.
8 . The charging device of claim 6 , wherein the one or more ADCs comprise: a first ADC configured to capture a first sample of current at a first sampling point in a first sampling cycle; and a second ADC configured to capture a first sample of voltage at the first sampling point in the first sampling cycle.
9 . A charging device comprising: a resonant circuit comprising one or more power transmitting coils in a charging surface of the charging device; a driver circuit configured to provide a charging current to the resonant circuit; and a controller configured to: determine an average transmitted power using samples of current and voltage captured from the resonant circuit; and determine that a foreign object is located on or near the charging surface when the average transmitted power exceeds a measurement of received power provided by a receiving device and parasitic losses associated with the charging; and a clock generating circuit configured to: divide a root clock frequency by a first integer to obtain a sampling clock frequency that determines frequency of a sampling cycle in which the samples of current and voltage captured from the resonant circuit; and divide the root clock frequency by a second integer to obtain a charging clock frequency that controls frequency of the charging current, wherein the first integer and the second integer have a largest common divisor of 1.
10 . The charging device of claim 6 , wherein the parasitic losses are attributable to metallic or magnetically permeable components of the charging device.
11 . A non-transitory processor-readable storage medium having instructions stored thereon which, when executed by at least one processor in a charging device, cause the processor to: cause a charging current to be provided to a resonant circuit that includes one or more power transmitting coils in a charging surface of a wireless charging device; determine an average transmitted power using samples of current and voltage captured from the resonant circuit; determine that a foreign object is located on or near the charging surface when the average transmitted power exceeds a measurement of received power provided by a receiving device and parasitic losses associated with the wireless charging device; and capture the samples of current and voltage in a first sampling cycle and a second sampling cycle, each sampling cycle having a period that spans a plurality of periods of a cycle of the charging current, wherein each sampling cycle includes a plurality of sampling points occurring at mutually different phases of the cycle of the charging current, and wherein a first sample of current is captured at the first sampling point and a first sample of voltage is captured at a corresponding first sampling point in the second sampling cycle.
12 . The non-transitory processor-readable storage medium of claim 11 , wherein the instructions cause the processor to: capture the samples of current and voltage in a single sampling cycle that has a period spanning a plurality of periods of a cycle of the charging current, wherein each sampling cycle includes a plurality of sampling points occurring at mutually different phases of the cycle of the charging current, and wherein samples of current and voltage are captured simultaneously at each sampling point in the plurality of sampling points in a single sampling cycle.
13 . The non-transitory processor-readable storage medium of claim 11 , wherein the instructions cause the processor to: divide a root clock frequency by a first integer to obtain a sampling clock frequency that determines frequency of a sampling cycle in which the samples of current and voltage captured from the resonant circuit; and divide the root clock frequency by a second integer to obtain a charging clock frequency that controls frequency of the charging current, wherein the first integer and the second integer have a largest common divisor of 1.

Description

PRIORITY CLAIM This application claims priority to and the benefit of provisional patent application No. 63/233,716 filed in the United States Patent Office on Aug. 16, 2021 and the entire content of this provisional application is incorporated herein by reference as if fully set forth below in its entirety and for all applicable purposes. TECHNICAL FIELD The present invention relates generally to wireless charging of batteries, including batteries in mobile computing devices, and more particularly to detection of devices placed near a charging device. BACKGROUND Wireless charging systems have been deployed to enable certain types of devices to charge internal batteries without the use of a physical charging connection. Devices that can take advantage of wireless charging include mobile processing and/or communication devices. Standards, such as the Qi standard defined by the Wireless Power Consortium enable devices manufactured by a first supplier to be wirelessly charged using a charger manufactured by a second supplier. Standards for wireless charging are optimized for relatively simple configurations of devices and tend to provide basic charging capabilities. Improvements in wireless charging capabilities are required to support continually increasing complexity of mobile devices and changing form factors. For example, there is a need for a faster, lower power detection techniques that enable a charging device to detect and locate chargeable devices on a surface of a charging device and for improved techniques for thermal management. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an example of a charging cell that may be provided on a charging surface provided by a wireless charging device in accordance with certain aspects disclosed herein. FIG. 2 illustrates an example of an arrangement of charging cells provided on a single layer of a segment of a charging surface provided by a wireless charging device in accordance with certain aspects disclosed herein. FIG. 3 illustrates an example of an arrangement of charging cells when multiple layers of charging cells are overlaid within a segment of a charging surface provided by a wireless charging device in accordance with certain aspects disclosed herein. FIG. 4 illustrates the arrangement of power transfer areas provided by a charging surface of a charging device that employs multiple layers of charging cells configured in accordance with certain aspects disclosed herein. FIG. 5 illustrates a wireless power transmitter that may be provided in a charger base station in accordance with certain aspects disclosed herein. FIG. 6 illustrates a configuration of devices involved in a wireless power transfer when an interfering foreign object is present. FIG. 7 provides an example of a cross-sectional view illustrating a portion of a wireless power transmitter and a wireless power receiver during a wireless power transfer. FIG. 8 illustrates a first example of a wireless charging device configured to sample voltage and current in a resonant circuit according to certain aspects of this disclosure. FIG. 9 illustrates an example of a sampling scheme configured in accordance with certain aspects of this disclosure. FIG. 10 illustrates an example of signal reconstruction from voltage and current values sampled in accordance with certain aspects of this disclosure. FIG. 11 illustrates a second example of a wireless charging device configured to sample voltage and current in a resonant circuit according to certain aspects of this disclosure. FIG. 12 illustrates an example of a sampling scheme using a single sampling device configured in accordance with certain aspects of this disclosure. FIG. 13 illustrates one example of an apparatus employing a processing circuit that may be adapted according to certain aspects disclosed herein. FIG. 14 illustrates a method for operating a charging device in accordance with certain aspects of this disclosure. DETAILED DESCRIPTION The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts. Several aspects of wireless charging systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawing by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements