Temperature control of wireless charging pads

Abstract

A wireless charging device has a controller and at least one coil located near the surface of the charging device and configured to transmit an electromagnetic field, and a first driver circuit configured to drive the transmitting coil. The controller is configured to cause the driver circuit to provide a charging current to the transmitting coil, to decode a request for lower transmitting power from the modulation of the charging current, to reduce the amplitude of the charging current in response to the request for lower transmitting power when the temperature measured at the surface of the charging device is below a critical temperature, and to initiate a cooling sequence when the temperature measured at the surface of the charging device is equal to or greater than the critical temperature. In one example, the request for lower transmitting power may be provided as an ASK-modulated signal superimposed on the charging current.

Description

Technology Field

[0001] Claim of priority

[0002] This application claims priority and benefit to patent application No. 17 / 087,610 filed with the U.S. Patent and Trademark Office on November 2, 2020, the entire contents of said application are incorporated herein by reference as set forth below and for all applicable purposes.

[0003] The present invention generally relates to wireless charging of a battery including a battery of a mobile computing device, and more specifically to the detection and improvement of overheating during charging. Background Technology

[0004] Wireless charging systems are deployed to enable certain types of devices to charge their internal batteries without the use of a physical charging connection. Devices capable of utilizing wireless charging include mobile processing devices and / or communication devices. Standards, such as the Qi standard defined by the Wireless Power Consortium, allow devices manufactured by a first supplier to be wirelessly charged using chargers manufactured by a second supplier. Standards for wireless charging tend to be optimized for relatively simple device configurations and provide basic charging capabilities.

[0005] Improvements to wireless charging capabilities are required to support the continuously increasing complexity and changing form factors of mobile devices. For example, there is a need for faster, lower-power detection technology that enables a charging device to detect and locate a chargeable device on the surface of the charging device, and to detect the removal or relocation of the chargeable device during wireless charging operations. Brief explanation of the drawing

[0006] FIG. 1 illustrates an example of a charging cell that may be provided on a charging surface provided by a wireless charging device according to a specific embodiment disclosed herein. FIG. 2 illustrates an example of an array of charging cells provided on a single layer of a segment of a charging surface provided by a wireless charging device according to a specific embodiment disclosed herein. FIG. 3 illustrates an example of an arrangement of charging cells when a plurality of layers of charging cells are overlaid within a segment of a charging surface provided by a wireless charging device according to a specific embodiment disclosed herein. FIG. 4 illustrates an arrangement of power transmission regions provided by a charging surface of a charging device using a plurality of layers of a charging cell configured according to a specific embodiment disclosed herein. FIG. 5 illustrates a wireless transmitter that can be provided to a charger base station according to a specific embodiment disclosed herein. FIG. 6 illustrates a microcontroller that supports ASK demodulation according to a specific embodiment disclosed herein. FIG. 7 illustrates an example of an encoding scheme that can be adapted to digitally encode messages exchanged between a power receiver and a power transmitter according to a specific embodiment disclosed herein. FIG. 8 illustrates a topology that supports direct driving of a transmitting coil in a wireless charger adapted according to a specific embodiment disclosed herein. FIG. 9 provides a two-dimensional view illustrating a temperature sensor provided on the surface of a wireless charging device according to a specific embodiment of the present disclosure. FIG. 10 provides a cross-sectional view illustrating the configuration of a temperature sensor provided according to a specific embodiment of the present disclosure. FIG. 11 illustrates a cooling process managed by a wireless charging device according to a specific embodiment of the present disclosure. FIG. 12 illustrates a first example of a method for managing thermal cooling in a device being charged by a multi-coil wireless charging system according to a specific aspect of the present disclosure. FIG. 13 illustrates an example of a device using a processing circuit that can be adapted according to a specific embodiment disclosed herein. FIG. 14 illustrates a second example of a method for managing thermal cooling in a device being charged by a multi-coil wireless charging system according to a specific aspect of the present disclosure. Specific details for implementing the invention

[0007] The detailed description set forth below, together with the attached drawings, is intended to describe various configurations and is not intended to represent only the configurations in which the concepts described herein can be implemented. The detailed description includes specific details to provide a complete understanding of the various concepts. However, it will be apparent to those skilled in the art that such concepts can be implemented without these specific details. In some cases, well-known structures and components are depicted in block diagram form to avoid obscuring such concepts.

[0008] Several embodiments of a wireless charging system will now be presented with reference to various devices and methods. These devices and methods will be described in the following detailed description and will be illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on design constraints and specific applications imposed on the overall system.

[0009] For example, an element, or any part of an element, or any combination of elements may be implemented as a “processing system” comprising one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. One or more processors in a processing system may execute software. Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description languages, or otherwise. Software may reside on a processor-readable storage medium.A processor-readable storage medium, which may also be referred to herein as a computer-readable medium, may include, for example, a magnetic storage device (e.g., a hard disk, a floppy disk, a magnetic strip), an optical disc (e.g., a compact disc (CD), a digital multifunction disc (DVD)), a smart card, a flash memory device (e.g., a card, a stick, a key drive), a near-field communication (NFC) token, random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, a removable disk, a carrier, a transmission line, and any other suitable medium for storing and transmitting software. The computer-readable medium may reside within a processing system, outside a processing system, or be distributed across a number of entities including a processing system. The computer-readable medium may be implemented in a computer-program product. For example, a computer-program product may include the computer-readable medium in a packaging material. Those skilled in the art will recognize the best implementation of the described functions presented throughout this disclosure, depending on the overall design constraints imposed on the entire system and the specific application.

[0010] outline

[0011] Specific aspects of the present disclosure relate to systems, devices, and methods applicable to wireless charging devices and technologies. A charging cell may be composed of one or more induction coils to provide a charging surface in a charging device, wherein the charging surface enables the charging device to wirelessly charge a plurality of chargeable devices. The location of a device to be charged may be detected through a sensing technique that associates the location of the device with a change in physical properties centered on a known location on the charging surface. The detection of the location may be implemented using capacitive, resistive, inductive, touch, pressure, load, strain, and / or other suitable types of sensing.

[0012] In one aspect of the present disclosure, the device comprises a battery charging power source, a plurality of charging cells comprising a matrix, a first plurality of switches each configured such that a switch connects a row of coils of the matrix to a first terminal of the battery charging power source, and a second plurality of switches each configured such that a switch connects a column of coils of the matrix to a second terminal of the battery charging power source. Each of the plurality of charging cells may include one or more coils surrounding a power transmission area. The plurality of charging cells may be arranged adjacent to the charging surface of the charging device without overlapping of the power transmission areas of the charging cells in the plurality of charging cells.

[0013] In some cases, the device may also be referred to as a charging surface. Power may be transmitted wirelessly to a receiving device located anywhere on the surface of the device. The device may have an arbitrarily defined size and / or shape and may be placed regardless of any individual placement location possible for charging. Multiple devices may be charged simultaneously on a single charging surface. The device may track the motion of one or more devices across the charging surface. The specific concepts disclosed herein apply equally to a charging device having a single transmitting coil or charging cell.

[0014] In various embodiments of the present disclosure, a wireless charging device configured for multi-device charging may determine, calculate, or estimate when an overtemperature state exists in one of a plurality of devices being charged simultaneously. The wireless charging device may take measures to reduce the temperature in a receiving device identified as having an overtemperature state. The wireless charging device may configure a driver circuit to drive a transmitting coil placed near the surface of the device, cause the driver circuit to provide a charging current to the transmitting coil, decode a request for lower transmit power from the modulation of the charging current, and determine whether an overtemperature state exists in or is indicated thereon in the device being charged. An overtemperature state may correspond to a battery temperature exceeding a maximum temperature defined by a standard, protocol, or designer. An overtemperature state may be indicated when the temperature measured at the surface of the charging device exceeds a threshold temperature. The wireless charging device may reduce the amplitude of the charging current in response to a request for lower transmit power when the temperature measured at the surface of the charging device is below the threshold temperature. A wireless charging device can initiate a cooling sequence when the temperature measured on the surface of the charging device is equal to or exceeds a critical temperature.

[0015] charging cell

[0016] According to a specific embodiment disclosed herein, a charging surface may be provided using a charging cell in a charging device, wherein the charging cell is disposed adjacent to the charging surface. In one embodiment, the charging cell is disposed on one or more layers of the charging surface according to a honeycomb packaging configuration. The charging cell may be implemented using one or more coils capable of inducing a magnetic field along an axis substantially orthogonal to the charging surface adjacent to the coil. In this description, a charging cell may refer to an element having one or more coils, wherein each coil is configured to generate an additional electromagnetic field for a field generated by another coil of the charging cell and oriented along or near a common axis.

[0017] In some embodiments, the charging cell comprises coils that are stacked along a common axis and / or overlap, thereby contributing to an induced magnetic field substantially orthogonal to the charging surface. In some embodiments, the charging cell comprises coils arranged within a defined portion of the charging surface and contributing to an induced magnetic field within a substantially orthogonal portion of the charging surface associated with the charging cell. In some embodiments, the charging cell may be configurable by dynamically providing an activation current to the coils included in the defined charging cell. For example, the charging device may comprise a plurality of coil stacks disposed across the charging surface, and the charging device may detect the location of the device to be charged and select some combination of the coil stacks to provide a charging cell adjacent to the device to be charged. In some cases, the charging cell may comprise a single coil or be characterized as a single coil. However, it should be understood that the charging cell may comprise a plurality of stacked coils and / or a plurality of adjacent coils or coil stacks. The coils may be referred to herein as a charging coil, a wireless charging coil, a transmitter coil, a transmitting coil, a power transmitting coil, a power transmitter coil, etc.

[0018] FIG. 1 illustrates an example of a charging cell (100) that may be arranged and / or configured to provide a charging surface of a charging device. As described herein, the charging surface may comprise an array of charging cells (100) provided on one or more substrates (106). A circuit comprising one or more integrated circuits (ICs) and / or separate electronic components may be provided on one or more substrates (106). The circuit may include a driver and a switch used to control the current provided to a coil used to transmit power to a receiving device. The circuit may be configured as a processing circuit comprising one or more processors and / or one or more controllers that may be configured to perform the specific functions disclosed herein. In some cases, part or all of the processing circuit may be provided outside the charging device. In some cases, a power source may be coupled to the charging device.

[0019] A charging cell (100) may be provided in close proximity to an external surface area of ​​a charging device, and one or more devices may be placed thereon for charging. The charging device may include multiple instances of the charging cell (100). In one example, the charging cell (100) has a substantially hexagonal shape surrounding one or more coils (102), which may be constructed using conductors, wires, or circuit board traces capable of receiving sufficient current to generate an electromagnetic field in a power transmission area (104). In various embodiments, some coils (102) may have a substantially polygonal shape including the hexagonal charging cell (100) exemplified in FIG. 1. Other embodiments provide coils (102) having different shapes. The shape of the coils (102) may be determined at least partially by the capabilities and limitations of the manufacturing technology and / or determined to optimize the layout of the charging cell on a substrate (106), such as a printed circuit board substrate. Each coil (102) may be implemented using a wire, a printed circuit board trace, and / or other connectors of a spiral configuration. Each charging cell (100) may span two or more layers separated by an insulator or substrate (106) so that coils (102) of different layers are centered around a common axis (108).

[0020] FIG. 2 illustrates an example of an arrangement (200) of charging cells (202) provided on a single layer of segments of the charging surface of a charging device that may be adapted according to a specific embodiment disclosed herein. The charging cells (202) are arranged according to a honeycomb packaging configuration. In this example, the charging cells (202) are arranged end-to-end without overlap. This arrangement may be provided without through-holes or wire interconnections. Other arrangements are possible, including arrangements where parts of the charging cells (202) overlap. For example, wires of two or more coils may be interleaved to some extent.

[0021] FIG. 3 illustrates an example of an arrangement of charging cells from two perspectives (e.g., a top view (300) and a profile view) when a plurality of layers are overlaid within a segment of a charging surface that can be adapted according to a specific embodiment disclosed herein. Layers of charging cells (302, 304, 306, 308) are provided within a segment of the charging surface. The charging cells within each layer of charging cells (302, 304, 306, 308) are arranged according to a honeycomb packaging configuration. In one example, layers of charging cells (302, 304, 306, 308) may be formed on a printed circuit board having four or more layers. The arrangement of charging cells (100) may be selected to provide complete coverage of a designated charging area adjacent to the illustrated segment.

[0022] FIG. 4 illustrates an arrangement of power transmission areas provided on a charging surface (400) utilizing a plurality of layers of a charging cell configured according to a specific embodiment disclosed herein. The illustrated charging surface is configured from four layers of charging cells (402, 404, 406, 408). In FIG. 4, each power transmission area provided by a charging cell in the first layer of charging cell (402) is marked as "L1", each power transmission area provided by a charging cell in the second layer of charging cell (404) is marked as "L2", each power transmission area provided by a charging cell in the third layer of charging cell (406) is marked as "L3", and each power transmission area provided by a charging cell in the fourth layer of charging cell (408) is marked as "L4".

[0023] wireless transmitter

[0024] FIG. 5 illustrates a wireless transmitter (500) that may be provided to a charger base station. A controller (502) may receive a feedback signal that is filtered or otherwise processed by a conditioning circuit (508). The controller may control the operation of a driver circuit (504) that provides an alternating current to a resonant circuit (506) comprising a capacitor (512) and an inductor (514). The resonant circuit (506) may also be referred to herein as a tank circuit, an LC tank circuit, or an LC tank, and the voltage (516) measured at the LC node (510) of the resonant circuit (506) may be referred to as the tank voltage.

[0025] A wireless transmitter (500) may be used by a charging device to determine whether a compatible device is placed on a charging surface during a discovery procedure. For example, the charging device may determine whether a compatible device is placed on a charging surface by transmitting an intermittent test signal (active or digital ping) through the wireless transmitter (500), wherein a resonant circuit (506) may detect or receive an encoded signal when the compatible device responds to the test signal. The charging device may be configured to activate one or more coils in at least one charging cell after receiving a response signal defined by a standard, convention, manufacturer, or application. In some examples, the compatible device may respond to the ping by transmitting the received signal strength so that the charging device can discover the optimal charging cell to be used to charge the compatible device. The discovery procedure may allow the charging device to determine the charging configuration to be used to charge the discovered device. The charging configuration can define one or more transmitting coils or charging cells to receive the charging current when charging the discovered device, the level of power to be transmitted to the discovered device, and the maximum and minimum levels of power to be transmitted to the discovered device.

[0026] Passive ping technology may use voltage and / or current measured or observed at an LC node (510) to identify the presence of a receiving coil in proximity to a charging pad of a device adapted according to a specific embodiment disclosed herein. In many conventional wireless charger transmitters, a circuit is provided to measure voltage at the LC node (510) or to measure current in an LC network. These voltages and currents may be monitored for power regulation purposes or to support communication between devices. In the example illustrated in FIG. 5, it is considered that while the voltage at the LC node (510) is monitored, the current may be additionally or alternatively monitored to support passive ping, where a short pulse is provided to the resonant circuit (506). Passive ping (initial voltage V The response of the resonant circuit (506) to 0) is the voltage of the LC node (510) V LC It can be expressed by ), for example as follows:

[0027] (Equation 1).

[0028] According to certain embodiments disclosed herein, coils of one or more charging cells may be optionally activated to provide an optimal electromagnetic field for charging a compatible device. In some cases, coils may be assigned to charging cells, and some charging cells may overlap with other charging cells. In the latter case, the optimal charging configuration may be selected at the charging cell level. In other cases, charging cells may be defined based on the placement of the device to be charged on the surface of the charging device. In these other cases, the combination of coils activated for each charging event may be variable. In some embodiments, the charging device may include a driver circuit capable of selecting one or more cells and / or one or more predefined charging cells for activation during a charging event.

[0029] A charging device may define a charging configuration based in part on information received from a device to be charged. The device to be charged may communicate its identity and requested power transfer level by modulating the current received through power transfer from the charging device. The device to be charged may modulate the received current by changing the load it provides to the receiving coil. The change in load is reflected through electromagnetic coupling to the charging device, which can capture the modulation signal by measuring the current flowing through the transmitting coil or the tank voltage. In one example, the information may be encoded in the tank voltage using Amplitude Shift Key (ASK) modulation.

[0030] FIG. 6 illustrates an example of a processing circuit (600) that may be configured to receive and decode an ASK-modulated signal. The processing circuit (600) includes a processor (602) that may be coupled to a memory device (604) and / or a register capable of storing a message to be transmitted using the ASK-modulated signal (612) and / or a message to be decoded from the received ASK-modulated signal (612). The processing circuit (600) includes an ASK decoder (606) that may be implemented using hardware, software, or some combination of hardware and software. The ASK decoder (606) may use a clock signal received from a clock generation or recovery circuit to control the timing of the transmitted ASK-modulated signal (612) and to control the sampling and decoding of the received ASK-modulated signal (612).

[0031] FIG. 7 illustrates an example of an encoding scheme (700, 720) that can be adapted to digitally encode messages exchanged between a power receiver and a power transmitter. In the first example, a differential bi-phase encoding scheme (700) encodes binary bits in the phase of a data signal (704). In the illustrated example, each bit of a data byte (706) is encoded in the corresponding cycle (708) of an encoder clock signal (702). The value of each bit is encoded in the presence or absence of a transition (710) (phase change) of the data signal (704) during the corresponding cycle (708).

[0032] In the second example, the power supply (724) is encoded using a power signal amplitude encoding method (720). In the illustrated example, the binary bits of the data byte (726) are encoded at the level of the power supply (724). Each bit of the data byte (726) is encoded in the corresponding cycle (728) of the encoder clock signal (722). The value of each bit is encoded at the voltage level of the power supply (724) for the nominal 100% voltage level (730) of the power supply (724) during the corresponding cycle (708).

[0033] Selectively activate the coil

[0034] According to certain embodiments disclosed herein, a transmitting coil of one or more charging cells may be optionally activated to provide an optimal electromagnetic field for charging a compatible device. In some cases, the transmitting coil may be assigned to a charging cell, and some charging cells may overlap with other charging cells. In the latter case, the optimal charging configuration may be selected at the charging cell level. In other cases, the charging cells may be defined based on the placement of the device to be charged on the surface of the charging device. In these other cases, the combination of coils activated for each charging event may be variable. In some embodiments, the charging device may include a driver circuit capable of selecting one or more cells and / or one or more predefined charging cells for activation during a charging event.

[0035] FIG. 8 illustrates an example of a topology (800) in which each coil or charge cell is driven individually and / or directly by a driver circuit (802) according to a specific embodiment disclosed herein. The driver circuit (802) may be configured to select one or more coils or charge cells (100) from a group of coils (804) to charge a receiving device. It will be understood that the concept disclosed herein with respect to a charge cell (100) may be applied to the selective activation of individual coils or coil stacks. An unused charge cell (100) does not receive current flow. A relatively large number of charge cells (100) may be used, and a switching matrix may be used to drive individual coils or groups of coils. In one example, a first switching matrix may form a connection defining a group of charge cells or coils to be used during a charging event, and a second switching matrix may be used to activate a group of charge cells and / or selected coils.

[0036] In some embodiments, a matrix switching scheme may be used to select a charging cell (100) from a group of coils (804) to charge a receiving device. A relatively large number of charging cells (100) may be used in the honeycomb packaging configuration exemplified in FIGS. 2 and 3, and at least some of the charging cells (100) may be logically arranged or connected in a switching matrix. The use of a switching matrix can significantly reduce the number of switching components required to operate a network of tuned LC circuits. For example, N The individual connected cells are at least N While it requires two switches, N having cells A 2D matrix is It can be operated with switches. In one example, a 9-cell implementation can be implemented as a 3x3 matrix using 6 switches, thus saving 3 switches. In another example, a 16-cell implementation can be implemented as a 4x4 matrix using 8 switches, thus saving 8 switches. During operation, at least 2 switches are closed to actively couple one coil to the wireless transmitter and / or receiver circuit. Multiple switches can be closed at once to facilitate the connection of multiple coils to the wireless transmitter and / or receiver circuit. Multiple switches can be closed, for example, to enable an operating mode that drives multiple transmitting coils when transmitting power to a receiving device.

[0037] Thermal control of multi-device, multi-coil wireless chargers

[0038] Batteries used in mobile communication devices can be sensitive to heat generation issues during high-current draw or high-current charging operations. Batteries installed in devices may be susceptible to overheating when the device has limited heatsink or heat dissipation capabilities. For example, batteries in mobile communication devices may be located within a small space nearly equal to the battery's volume to restrict airflow. Restricted airflow can suppress the dissipation of heat generated through losses during battery charging and discharging, leading to heat accumulation near the battery and throughout the mobile communication device. Controlling heat generation, accumulation, and dissipation is necessary to prevent damage to the battery and to avoid potential runaway chemistry that could cause the explosion or combustion of the battery's components. Specific industries define and publish standards and protocols for managing battery operation in a manner that protects the battery from overheating. For example, the Japan Electronics and Information Technology Industries Association (JEITA) defines operating limits for lithium-ion batteries. Lithium-ion batteries are widely used in portable electronic devices, partly due to their high energy density, and JEITA guidelines and procedures are intended to prevent the ignition of lithium-ion batteries.

[0039] JEITA defines operating conditions that affect lithium-ion batteries operating at elevated temperatures. In one example, pulsed current charging technology is used to improve the lifespan, charging rate, charging capacity, discharge function, and temperature control of lithium-ion batteries. JEITA defines duty cycles ranging from 20% to 80%.

[0040] Certain aspects of the present disclosure provide techniques, circuits, and methods for monitoring, limiting, and / or controlling overtemperature events in a chargeable device during battery charging, including when the charging device is a multi-device, multi-coil wireless charger. Limiting and improving overtemperature events through modifications to the wireless charger or to the charging configuration defined by it can avoid the imposition of inefficient charging duty cycles when operating the chargeable device according to the JEITA protocol.

[0041] Wireless chargers typically do not recognize the temperature or state of the battery charge in the device being charged. The device being charged can monitor the battery temperature and respond to temperature issues by requesting lower charge power or terminating charging until cooling is complete. Requests for lower charge power or to terminate charging by the device being charged can be made for various reasons other than temperature-related ones. For example, a reduction in charge power may be requested when the device's battery is at full capacity or approaching full capacity. Therefore, requests for a change in charge power serve as an unreliable indicator to distinguish requests based on battery charge and temperature status when the charging device does not recognize the state of the device's battery charge.

[0042] In one aspect of the present disclosure, a temperature measured on the surface of a charging device (also referred to as a "charging pad") may be used to determine a possible reason for a request to change charging power. In one example, when the temperature of the surface of the charging device is nominal or within a preset range, a request to reduce charging power may indicate that the battery of the device being charged is at full capacity or approaching full capacity. In another example, when the temperature of the surface of the charging device exceeds a nominal maximum temperature or is outside a preset temperature range, a request to reduce charging power may indicate that the battery of the device being charged is experiencing an elevated temperature.

[0043] FIGS. 9 and 10 illustrate configurations (900, 1000, 1020) of a multi-device wireless charging device that can be instrumented to measure temperature according to a specific embodiment of the present disclosure. FIG. 9 illustrates temperature sensors (9041-9046 and 9061-9064) provides a two-dimensional view of the configuration (900) of a wireless charging device arranged around the perimeter of an array of charging cells (LP1-LP18) provided on the surface (902) of the wireless charging device. Horizontal temperature sensors (9041-9046) and A combination of vertical temperature sensors (9061-9064) can enable an estimated or calculated mapping of temperature across the surface (902) of the wireless charging device. Temperature sensors (9041-9046 and 9061-9064) may include a thermocouple or other thermometric device.

[0044] In another example, the temperature sensor may be provided at the center of each charging cell or between pairs of each charging cell. FIG. 10 shows a temperature sensor (10081-10083) provided in vertical alignment with the corresponding charging cells (10041-10043) and A cross-sectional view of different configurations (1000, 1020) of 10281-10283 is provided. Temperature sensors (10081-10083) and 10281-10283) may include a thermocouple or other temperature measuring device. The temperature sensor (10081-10083, 10281-10283) may be embedded in, attached to, or otherwise provided to be in thermal communication with a thermally conductive layer (1006, 1026) located on or near the surface of the wireless charging device.

[0045] A thermally conductive layer (1006, 1026) may additionally serve as electrical insulation or provide, enhance, or configure the electromagnetic properties of the surface (902) of the wireless charging device. In a first configuration (1000), the thermally conductive layer (1006) is provided on or near the surface (902) of the wireless charging device and below the charging cells (10041-10043). In a second configuration (1020), the thermally conductive layer (1026) is provided on a layer above the charging cells (10041-10043). In other configurations (not shown), a temperature sensor may be provided on the same layer as the charging cells and may be located at the center of each charging cell or between the charging cells. The wireless charging device may be configured to take the surface temperature into account when determining whether a request for reduced power transfer indicates that a battery temperature issue has been detected by the device being charged.

[0046] In some embodiments, temperature sensors (9041-9046, 9061-9064, 10081-10083 and 10281-10283) can be calibrated using an instrumented rechargeable device. In one example, the instrumented rechargeable device is placed on the surface (902) of the wireless charging device across one or more charging cells (10041-10043). Internal temperature measurements and temperature sensors (9041-9046, 9061-9064 or ) taken by the instrumented rechargeable device. Simultaneous measurements of surface temperatures captured by (10081-10083) can be compared and correlated to provide information available to the controller (1002) of the wireless charging device to estimate the internal temperature of the charging device during normal operation. In one example, the wireless charging device may be configured with a lookup table that can be indexed using the surface temperature of the wireless charging device to obtain an estimate of the internal temperature of the device being charged during normal operation.

[0047] According to a specific embodiment of the present disclosure, a wireless charging device may determine that a device being charged is attempting to cool based on a combination of information including pad or surface temperature and a request for power draw. The wireless charging device may assist cooling by reducing the charging power to a lower level while monitoring a change in temperature measured on the surface of the wireless charging device to estimate or infer that a change in temperature has occurred within the device being charged. The wireless charging device may terminate charging when the temperature cannot be sloped at a sufficient rate. The wireless charging device may reduce or terminate charging for one or more other devices when the temperature cannot be sloped at a sufficient rate after terminating charging for the device being cooled.

[0048] The graph (1100) of FIG. 11 illustrates a cooling process managed by a wireless charging device according to a specific embodiment of the present disclosure. The graph includes a curve representing a battery temperature (1102) measured or estimated by the device being charged, which may have some correspondence or correlation with the temperature measured on the surface of the wireless charging device. The wireless charging device may estimate the internal temperature of the device being charged based on the temperature measured on the surface of the wireless charging device.

[0049] Initially, the battery temperature (1102) increases until a high temperature limit (1130) is reached at a first time point (1104). The high temperature limit (1130) may correspond to a maximum temperature defined for the battery of the device being charged. A protocol or industry standard may limit the charging power when the maximum temperature is reached. The device being charged may issue a request to modify the transmitted power, which would result in a lower power transfer rate. In one example, the device being charged may issue a request intended to ensure that the power transfer complies with a duty cycle defined by a protocol or standard for charging a high-temperature battery. Limitations imposed on charging via a duty cycle may cause inefficiencies in charging and temperature reduction.

[0050] In one embodiment, the wireless charging device may associate an overtemperature event with a request to modify transmitted power when the temperature measured on the surface of the wireless charging device exceeds a threshold temperature level indicating that the battery temperature (1102) of the device being charged has reached a high temperature limit (1130) or is within the range of the high temperature limit (1130). The wireless charging device may enter a cooling mode (1120) when it is determined that an overtemperature event has occurred. The cooling mode (1120) may continue until the measured or estimated battery temperature (1102) reaches a low temperature threshold (1132). A plurality of phases or stages may be defined for the cooling mode (1120).

[0051] The first stage (1122) of the cooling mode (1120) begins after a thermal limit is triggered or after a high temperature limit (1130) is reached. In the first stage (1122), the wireless charging device may reduce the transmitted power to a lower level that does not trigger or cause disconnection from the device being charged. The lower level of transmitted power may be associated with the lowest level of dissipated power for the device being charged, and a drop in the measured or estimated battery temperature (1102) may be expected. A limited duration may be defined for the cooling mode (1120), and the battery temperature (1102) may be expected to drop to the level of the low temperature threshold (1132) within the duration of the cooling mode (1120). The thermal gradient of the battery temperature (1102) can be monitored to determine whether the battery temperature (1102) is likely to fall below a low temperature threshold (1132) during the cooling mode (1120). In the illustrated example, the rate of change of the battery temperature (1102) is variable and may feature a number of temperature gradients (1106, 1108, 1110). The temperature gradients (1106, 1108, 1110) may be calculated based on the difference between the measured or estimated battery temperature (1102) over a period defined by a specified timer interval.

[0052] The initial temperature gradient (1106) corresponds to the probability that the battery temperature (1102) will reach the low temperature threshold (1132) while the cooling mode (1120) is active. The rate of change of the battery temperature (1102) decreases as indicated by two later-occurring temperature gradients (1108 and 1110) and leveling to the zero gradient (1112). Thus, in the illustrated example, it is evident that the measured or estimated battery temperature (1102) will not reach the low temperature threshold (1132) while the cooling mode (1120) is active. In this example, the first stage (1122) is terminated and the second stage (1124) is initiated.

[0053] In the second stage (1124), the wireless charging device terminates power transmission to the device being charged. The absence of transmitted power eliminates energy dissipation occurring from charging, and a drop (1114) in the battery temperature (1102) is expected due to the absence of other heating sources. The thermal gradient of the battery temperature (1102) may be monitored to determine whether there is a possibility that the battery temperature (1102) will fall below a low temperature threshold (1132) during a cooling mode (1120) within a pre-configured maximum cooling period. The pre-configured maximum cooling period may be defined by standards, protocols, or based on information identifying the type or function of the device being charged. The pre-configured maximum cooling period may be specified by a charging configuration defined for the device being charged. In the illustrated example, the rate of change of the battery temperature (1102) has a gradient indicating that it remains constant or that there is no possibility that the battery temperature (1102) will fall below the low temperature threshold (1132). Here, the second stage (1124) ends and the third stage (1126) begins.

[0054] In the third stage (1126), the power level transmitted by the wireless charging device to one or more adjacent devices is reduced or terminated. In the third stage (1126), cooling is enforced across multiple devices, and the temperature measured in the charging cell accompanying the charging of adjacent devices may also be monitored. In some embodiments, a thermal cutoff or limit may be applied globally across the surface (902) of the wireless charging device to cause all devices to be cooled, thereby cooling the charging system including the wireless charging device and all devices placed on the surface (902) of the wireless charging device. The thermal gradient of the battery temperature (1102) may be monitored to determine whether there is a possibility that the battery temperature (1102) will drop below a low temperature threshold (1132) during the cooling mode (1120). In the illustrated example, a drop (1116) of the battery temperature (1102) occurs.

[0055] FIG. 12 is a flowchart (1200) illustrating a first example of a method for managing thermal cooling in a device being charged by a multi-coil wireless charging system. The method is performed by a controller (1002) in the multi-coil wireless charging system. The multi-coil wireless charging system can charge a number of chargeable devices simultaneously. In block (1202), the controller (1002) can detect the presence of a receiving device placed on or near the surface (902) of the multi-coil wireless charging system. The controller (1002) can interrogate and / or negotiate with the receiving device to create a charging configuration. Then, the controller (1002) can cause a charging current to be supplied to one or more transmitting coils of the multi-coil wireless charging system according to the charging configuration.

[0056] In block (1204), the controller (1002) can determine whether a temperature limit has been reached at the receiving device. The temperature limit may be related to the temperature of the battery being charged at the receiving device. The temperature limit may be determined to have been reached based on the temperature measured on the surface of the multi-coil wireless charging system. When the controller (1002) determines that the temperature limit has not been reached, charging continues in block (1202). When the controller (1002) determines that the temperature limit has been reached, the controller (1002) may interpret a request for power reduction from the receiving device as an indication that the receiving device is attempting to reduce its temperature, and the controller (1002) may proceed to block (1206).

[0057] In one example, the controller (1002) can determine whether the power level requested in block (1206) is below a minimum power level defined by the charging configuration, protocol, or system configuration. When the requested power level exceeds or is equal to the minimum power level, charging may continue at the reduced power level requested in block (1202). When the requested power level is below the minimum power level, the controller (1002) may determine that the receiving device is attempting to cool and may enter a cooling mode in block (1208). The receiving device may have requested a power level below the minimum power level to implement a duty cycle defined by the protocol.

[0058] In some cases, the controller (1002) may respond to a request for a change in transmitted power when the temperature limit is not reached and one or more requests regarding the charge power level received from the receiving device.

[0059] Example of a processing circuit

[0060] FIG. 13 illustrates an example of a hardware implementation for a device (1300) that can be integrated into a charging device or receiving device to enable a battery to be wirelessly charged. In some examples, the device (1300) may perform one or more of the functions disclosed herein. According to various aspects of the disclosure, an element as disclosed herein, or any part of an element, or any combination of elements may be implemented using a processing circuit (1302). The processing circuit (1302) may include one or more processors (1304) controlled by some combination of hardware and software modules. Examples of processors (1304) include microprocessors, microcontrollers, digital signal processors (DSPs), SoCs, Application Specific Integrated Circuits (ASICs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, sequencers, gated logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout this disclosure. One or more processors (1304) may include specialized processors that perform specific functions and can be configured, augmented, or controlled by one of the software modules (1316). One or more processors (1304) may be configured through a combination of software modules (1316) loaded during initialization and may be further configured by loading or unloading one or more software modules (1316) during operation.

[0061] In the illustrated example, the processing circuit (1302) may be implemented as a bus architecture generally represented by the bus (1310). The bus (1310) may include any number of interconnect buses and bridges depending on the specific application and overall design constraints of the processing circuit (1302). The bus (1310) links together various circuits including one or more processors (1304) and storage (1306). The storage (1306) may include memory devices and mass storage devices and may be referred herein as computer-readable media and / or processor-readable media. The storage (1306) may include ephemeral storage media and / or non-ephemeral storage media.

[0062] The bus (1310) can also link various other circuits such as timing sources, timers, peripherals, voltage regulators, and power management circuits. A bus interface (1308) can provide an interface between the bus (1310) and one or more transceivers (1312). In one example, a transceiver (1312) may be provided to enable the device (1300) to communicate with a charging or receiving device according to a standard-defined protocol. Depending on the nature of the device (1300), a user interface (1318) (e.g., a keypad, display, speaker, microphone, joystick) may also be provided and may be communicationly coupled to the bus (1310) directly or through the bus interface (1308).

[0063] The processor (1304) may be responsible for managing the bus (1310) and for general processing that may include the execution of software stored on a computer-readable medium that may include storage (1306). In this regard, a processing circuit (1302) including the processor (1304) may be used to implement any of the methods, functions, and techniques disclosed herein. Storage (1306) may be used to store data that is manipulated by the processor (1304) when executing the software, and the software may be configured to implement any of the methods disclosed herein.

[0064] One or more processors (1304) within the processing circuit (1302) may execute software. Software, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise, should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, algorithms, etc. Software may reside in a computer-readable form on storage (1306) or an external computer-readable medium. The external computer-readable medium and / or storage (1306) may include non-transient computer-readable media. A non-transient computer-readable medium includes, for example, a magnetic storage device (e.g., a hard disk, a floppy disk, a magnetic strip), an optical disk (e.g., a compact disk (CD) or a digital multifunction disk (DVD)), a smart card, a flash memory device (e.g., a “flash drive”, a card, a stick, or a key drive), RAM, ROM, programmable read-only memory (PROM), an erasable PROM (EPROM) including EEPROM, a register, a removable disk, and any other suitable medium for storing software and / or instructions that can be accessed and read by a computer. The computer-readable medium and / or storage (1306) may also include, for example, a carrier, a transmission line, and any other suitable medium for transmitting software and / or instructions that can be accessed and read by a computer. The computer-readable medium and / or storage (1306) may reside in the processing circuit (1302), in the processor (1304), outside the processing circuit (1302), or distributed across a number of entities including the processing circuit (1302).Computer-readable media and / or storage (1306) may be implemented in a computer program product. For example, a computer program product may include computer-readable media in a packaging material. Those skilled in the art will recognize how to best implement the described functions presented throughout this disclosure, depending on the overall design constraints imposed on the entire system and the specific application.

[0065] Storage (1306) may maintain and / or organize software, such as loadable code segments, modules, applications, programs, etc., which may be referred to herein as software modules (1316). Each software module (1316) may include instructions and data that contribute to a run-time image (1313) that controls the operation of one or more processors (1304) when installed or loaded on a processing circuit (1302) and executed by one or more processors (1304). When executed, specific instructions may cause the processing circuit (1302) to perform a function according to a specific method, algorithm, and process described herein.

[0066] Some of the software modules (1316) may be loaded during the initialization of the processing circuit (1302), and these software modules (1316) may configure the processing circuit (1302) to enable the performance of various functions disclosed herein. For example, some software modules (1316) may configure the logic circuit (2713) and / or internal devices of the processor (1304) and may manage access to external devices such as a transceiver (1312), a bus interface (1308), a user interface (1318), a timer, a mathematical coprocessor, etc. The software modules (1316) may include a control program and / or an operating system that interacts with interrupt handlers and device drivers and controls access to various resources provided by the processing circuit (1302). Resources may include memory, processing time, access to the transceiver (1312), the user interface (1318), etc.

[0067] One or more processors (1304) of the processing circuit (1302) may be multifunctional, and by them, parts of the software module (1316) are loaded and configured to perform different instances of the same function or different functions. One or more processors (1304) may be additionally adapted to manage background tasks initiated in response to input from, for example, a user interface (1318), a transceiver (1312), and a device driver. To support the performance of multiple functions, one or more processors (1304) may be configured to provide a multitasking environment, whereby each of the multiple functions is implemented as a set of tasks serviced by one or more processors (1304) as needed or desired. In one example, a multitasking environment may be implemented using a time-sharing program (1320) that passes control of a processor (1304) between different tasks, wherein each task returns control of one or more processors (1304) to the time-sharing program (1320) upon completion of any outstanding operation and / or in response to an input such as an interrupt. When a task controls one or more processors (1304), the processing circuit is effectively specialized for the purpose of being processed by a function associated with the control task. The time-sharing program (1320) may include an operating system, a main loop that passes control in a round-robin manner, a function that assigns control of one or more processors (1304) according to the priority of functions, and / or an interrupt-driven main loop that responds to external events by providing control of one or more processors (1304) to a handling function.

[0068] In one embodiment, the device (1300) comprises or operates a wireless charging device having a battery charging power source coupled to a charging circuit, a plurality of charging cells, one or more driver circuits (e.g., see FIG. 5 and FIG. 8) and a controller that may be included in one or more processors (1304). One or more driver circuits may be configured to decode an ASK-modulated message from a current flowing through a transmitting coil or a tank voltage. A plurality of charging cells may be configured to provide a charging surface. At least one coil may be configured to direct an electromagnetic field through a charge transfer area of ​​each charging cell. One or more driver circuits may include a first driver circuit configured to drive a transmitting coil located near the surface of the charging device. The controller may be configured to cause the driver circuit to provide a charging current to the transmitting coil, to decode a request for lower transmitting power from the modulation of the charging current, to reduce the amplitude of the charging current in response to the request for lower transmitting power when the temperature measured at the surface of the charging device is below a critical temperature, and to initiate a cooling sequence when the temperature measured at the surface of the charging device is equal to or greater than the critical temperature. In one example, the request for lower transmitting power may be provided as an ASK-modulated signal superimposed on the charging current.

[0069] In one example, one or more sensors may be configured to be thermally conductively coupled to the charging surface of the device (1300) and to provide periodic temperature measurements of at least a portion of the surface of the charging device. A critical temperature level is obtained from a prior calibration performed during the charging process. A temperature measured on the surface of the charging device that is equal to or greater than the critical temperature may indicate a charging device having an internal temperature that exceeds a temperature limit.

[0070] In some examples, a threshold voltage level is maintained in a lookup table. The lookup table may include threshold temperatures for each of multiple device types. The controller may be further configured to provide minimum transmit power in response to a request for lower transmit power when initiating a cooling sequence. The controller may be further configured to determine the gradient of a time series of temperature measurements taken on the surface of the charging device and to terminate the charging current when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during the cooling period.

[0071] In some examples, the controller is further configured to determine the gradient of a time series of temperature measurements taken on the surface of the charging device, and can reduce the power output of one or more other driver circuits in the charging device when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a cooling period.

[0072] In some examples, the controller is further configured to determine a first gradient of a first time series of temperature measurements taken on the surface of the charging device, terminate the charging current when the first gradient of the first time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a first cooling period, determine a second gradient of a second time series of temperature measurements taken on the surface of the charging device after terminating the charging current, and reduce the power output of one or more other driver circuits in the charging device when the second gradient of the second time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a second cooling period.

[0073] In a specific example, storage (1306) maintains commands and information, wherein the commands are configured to cause one or more processors (1304) to configure a driver circuit to drive a transmitting coil located near the surface of a charging device, to cause the driver circuit to provide a charging current to the transmitting coil, to decode a request for lower transmitting power from the modulation of the charging current, to reduce the amplitude of the charging current in response to the request for lower transmitting power when the temperature measured at the surface of the charging device is below a critical temperature, and to initiate a cooling sequence when the temperature measured at the surface of the charging device is equal to or greater than the critical temperature.

[0074] In some examples, the command may be configured to receive, acquire, or retrieve temperature measurements from one or more sensors thermally coupled to the surface of the charging device. The value of the critical temperature may be obtained from a prior calibration performed during the charging procedure. A temperature measured on the surface of the charging device that is equal to or exceeds the critical temperature may indicate a charging device having an internal temperature exceeding a temperature limit.

[0075] In some examples, a threshold voltage level is maintained in a lookup table. The lookup table may include threshold temperatures for each of multiple device types. The command may be configured to provide minimum transmit power in response to a request for lower transmit power when initiating a cooling sequence. The command may be configured to determine the gradient of a time series of temperature measurements taken on the surface of the charging device and to terminate the charging current when the gradient of the time series of temperature measurements indicates that the surface of the charging device will remain above a restart temperature defined for the device being charged during the cooling period. The command may be configured to determine the gradient of a time series of temperature measurements taken on the surface of the charging device and to reduce the power output of one or more other driver circuits in the charging device when the gradient of the time series of temperature measurements indicates that the surface of the charging device will remain above a restart temperature defined for the device being charged during the cooling period.

[0076] In some examples, the command may be configured to determine a first gradient of a first time series of temperature measurements taken on the surface of the charging device, terminate the charging current when the first gradient of the first time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a first cooling period, determine a second gradient of a second time series of temperature measurements taken on the surface of the charging device after terminating the charging current, and reduce the power output of one or more other driver circuits in the charging device when the second gradient of the second time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a second cooling period.

[0077] FIG. 14 is a flowchart (1400) illustrating a method for operating a charging device according to a specific aspect of the present disclosure. The method may be performed using a controller of the charging device. In block (1402), the controller may configure a driver circuit to drive a transmitting coil located near the surface of the charging device. In block (1404), the controller may cause the driver circuit to provide a charging current to the transmitting coil. In block (1406), the controller may decode a request for lower transmitting power from the modulation of the charging current. In block (1408), the controller may determine whether an overtemperature condition exists in the device being charged or is indicated thereon. An overtemperature condition may correspond to a battery temperature exceeding a maximum temperature defined by a standard, protocol, or designer. An overtemperature condition may be indicated when the temperature measured at the surface of the charging device exceeds a critical temperature. In one example, and in block (1410), the controller may reduce the amplitude of the charging current in response to a request for lower transmission power when the temperature measured on the surface of the charging device is below a critical temperature. In another example, and in block (1412), the controller may initiate a cooling sequence when the temperature measured on the surface of the charging device is equal to or exceeds the critical temperature.

[0078] In some examples, the controller may receive temperature measurements from one or more sensors that are thermally conductively bonded to the surface of the charging device. The sensors may be thermally conductively bonded to the surface of the charging device by being embedded in the surface, or by being fixed or attached to the surface of the charging device, for example, using a thermally conductive adhesive. In some cases, the value of the critical temperature may be obtained from a previous calibration during the charging process. In some cases, a temperature measured on the surface of the charging device that is equal to or exceeds the critical temperature indicates a charging device having an internal temperature that exceeds the temperature limit.

[0079] In a specific example, the threshold voltage level is maintained in a lookup table. The lookup table may include threshold voltage levels for each of a plurality of device types.

[0080] In certain examples, the cooling sequence may be initiated by providing minimum transmit power in response to a request for lower transmit power. The gradient of the time series of temperature measurements taken on the surface of the charging device may be determined, estimated, or calculated. The charging current may be terminated when the gradient of the time series of temperature measurements indicates that the surface of the charging device will remain above the restart temperature defined for the device being charged during the cooling period. The power output of one or more other driver circuits of the charging device may be reduced when the gradient of the time series of temperature measurements indicates that the surface of the charging device will remain above the restart temperature defined for the device being charged during the cooling period.

[0081] In a specific example, a first gradient of a first time series of temperature measurements taken on the surface of the charging device may be determined. The charging current may be terminated when the first gradient of the first time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a first cooling period. The first cooling period may be defined by a standard, protocol, or system designer. A second gradient of a second time series of temperature measurements taken on the surface of the charging device may be determined after the charging current is terminated. The power output of one or more other driver circuits of the charging device may be reduced when the second gradient of the second time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a second cooling period.

[0082] Some implementation examples are described in the following numbered clauses:

[0083] 1. A method for operating a charging device, comprising: configuring a driver circuit to drive a transmitting coil located near the surface of the charging device; causing the driver circuit to provide a charging current to the transmitting coil; decoding a request for lower transmitting power from the modulation of the charging current; reducing the amplitude of the charging current in response to the request for lower transmitting power when the temperature measured at the surface of the charging device is below a critical temperature; and

[0084] A method comprising the step of initiating a cooling sequence when the temperature measured at the surface of the charging device is equal to or exceeds the critical temperature.

[0085] 2. The method of claim 1, further comprising: the step of receiving a temperature measurement from one or more sensors thermally coupled to the surface of the charging device.

[0086] 3. A method according to claim 1 or 2, wherein the critical temperature is configured based on a prior calibration performed during the charging procedure.

[0087] 4. A method according to any one of claims 1 to 3, wherein the temperature measured on the surface of the charging device that is equal to or exceeds the critical temperature indicates a charging device having an internal temperature exceeding a temperature limit.

[0088] 5. A method according to any one of claims 1 to 4, wherein the critical temperature is defined in a lookup table.

[0089] 6. The method according to claim 5, wherein the lookup table includes a threshold temperature for each of a plurality of device types.

[0090] 7. A method according to any one of claims 1 to 6, wherein the step of initiating a cooling sequence comprises: providing minimum transmission power in response to a request for lower transmission power.

[0091] 8. The method of claim 7, further comprising: determining a gradient of a time series of temperature measurements measured on the surface of the charging device; and terminating the charging current when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a cooling period.

[0092] 9. The method of claim 7 or 8, further comprising: the step of determining a gradient of a time series of temperature measurements measured on the surface of the charging device; and the step of reducing the power output of one or more other driver circuits in the charging device when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a cooling period.

[0093] 10. A method according to any one of claims 7 to 9, wherein the temperature measured on the surface of the charging device that is equal to or exceeds the critical temperature indicates a charging device having an internal temperature exceeding a temperature limit.

[0094] 11. A charging device comprising: a driver circuit configured to drive a transmitting coil located near the surface of the charging device; and a controller, wherein the controller comprises: causing the driver circuit to provide a charging current to the transmitting coil; decoding a request for lower transmitting power from the modulation of the charging current; reducing the amplitude of the charging current in response to the request for lower transmitting power when the temperature measured at the surface of the charging device is below a critical temperature; and initiating a cooling sequence when the temperature measured at the surface of the charging device is equal to or greater than the critical temperature.

[0095] 12. The charging device according to claim 11, further comprising: that is, one or more sensors thermally conductively coupled to the surface of the charging device and configured to provide periodic temperature measurements of at least a portion of the surface of the charging device.

[0096] 13. A charging device according to claim 11 or 12, wherein the critical temperature is configured based on a prior calibration performed during the charging procedure.

[0097] 14. A charging device according to any one of claims 11 to 13, wherein the temperature measured on the surface of the charging device that is equal to or exceeds the critical temperature indicates a charging device having an internal temperature exceeding a temperature limit.

[0098] 15. A charging device according to any one of claims 11 to 14, wherein the critical temperature is defined in a lookup table.

[0099] 16. In paragraph 15, the charging device wherein the lookup table includes a threshold temperature for each of a plurality of device types.

[0100] 17. In any one of claims 11 through 16, the controller is further configured to provide a minimum transmission power in response to a request for the lower transmission power when initiating a cooling sequence, a charging device.

[0101] 18. The charging device according to claim 17, wherein the controller: determines a gradient of a time series of temperature measurements taken on the surface of the charging device; and further configured to terminate the charging current when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a cooling period.

[0102] 19. A charging device according to claim 17 or 18, wherein the controller: determines a gradient of a time series of temperature measurements taken on the surface of the charging device; and further configured to reduce the power output of one or more other driver circuits in the charging device when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a cooling period restart temperature defined for the device being charged during a cooling period.

[0103] 20. Any one of claims 17 to 19, wherein the controller is further configured to: determine a first gradient of a first time series of temperature measurements measured on the surface of the charging device; terminate the charging current when the first gradient of the first time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a first cooling period; determine a second gradient of a second time series of temperature measurements measured on the surface of the charging device after terminating the charging current; and reduce the power output of one or more other driver circuits in the charging device when the second gradient of the second time series of temperature measurements indicates that the surface of the charging device will be maintained above the restart temperature defined for the device being charged during a second cooling period.

[0104] The preceding description is provided to enable any person skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the art, and general principles defined herein may apply to other embodiments. Accordingly, the claims are not intended to be limited to the embodiments shown herein, but are intended to be consistent with the full scope of the linguistic claims, whereby reference to a singular element is not intended to mean "one and only one" unless specifically stated otherwise, but rather to mean "more than one." Unless otherwise specifically stated, the term "some" refers to more than one. All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure, which are known to or will be known to those skilled in the art, are intended to be expressly incorporated herein by reference and encompassed by the claims. Furthermore, nothing disclosed herein is intended to be exclusively for the public, regardless of whether such disclosure is explicitly used in the claims. If a claim element is not explicitly cited using the phrase “means for,” or in the case of a method claim, if the element is not cited using the phrase “step for,” it is not interpreted under the provisions of 35 USC §112, Paragraph 6.

Claims

Claim 1 A method for operating a charging device, comprising the steps of: configuring a driver circuit to drive a transmitting coil located near the surface of the charging device—the charging device being a multi-device, multi-coil wireless charger—; causing the driver circuit to provide a charging current to the transmitting coil; decoding a request for lower transmission power—the request being encoded by a charging device as a signal superimposed on the charging current—; obtaining a measured temperature of the surface of the charging device after receiving the request for lower transmission power; estimating whether an overtemperature state exists in at least one charging device located on the surface of the charging device based on the measured temperature of the surface of the charging device, and reducing the transmission power by reducing the amplitude of the charging current in accordance with the request for lower transmission power when the temperature measured on the surface of the charging device is below a critical temperature. A method comprising: estimating whether an overtemperature state exists in at least one charging device located on the surface of the charging device based on the measured temperature of the surface of the charging device, and initiating a cooling sequence when the temperature measured on the surface of the charging device is equal to or exceeds the critical temperature - wherein the step of initiating the cooling sequence includes providing minimum transmission power - and wherein the step of initiating the cooling sequence includes: defining a limited period for the cooling sequence. Claim 2 A method according to claim 1, further comprising the step of receiving a temperature measurement from one or more sensors thermally coupled to the surface of the charging device. Claim 3 A method according to claim 1, wherein the critical temperature is configured based on prior calibration performed during the charging procedure. Claim 4 A method according to claim 1, wherein the temperature measured on the surface of the charging device that is equal to or exceeds the critical temperature indicates that the internal temperature of the device being charged exceeds the temperature limit. Claim 5 A method according to claim 1, wherein the critical temperature is defined using a lookup table that associates the temperature measured at the surface of the charging device with an estimate of the internal temperature of the device being charged by the charging device. Claim 6 A method for operating a charging device, comprising the steps of: configuring a driver circuit to drive a transmitting coil located near the surface of the charging device—the charging device being a multi-device, multi-coil wireless charger—; causing the driver circuit to provide a charging current to the transmitting coil; decoding a request for lower transmission power—the request being encoded by a charging device as a signal superimposed on the charging current—; obtaining a measured temperature of the surface of the charging device after receiving the request for lower transmission power; estimating whether an overtemperature state exists in at least one charging device located on the surface of the charging device based on the measured temperature of the surface of the charging device, and reducing the transmission power by reducing the amplitude of the charging current in accordance with the request for lower transmission power when the temperature measured on the surface of the charging device is below a critical temperature. A method comprising the step of estimating whether an overtemperature state exists in at least one device being charged located on the surface of the charging device based on the measured temperature of the surface of the charging device, and initiating a cooling sequence when the temperature measured on the surface of the charging device is equal to or exceeds a critical temperature—the step of initiating the cooling sequence includes providing minimum transmission power—wherein the critical temperature is defined using a lookup table that associates the temperature measured on the surface of the charging device with an estimate of the internal temperature of the device being charged by the charging device, and the lookup table includes an estimate of the internal temperature for each of a plurality of device types. Claim 7 delete Claim 8 A method according to claim 1, further comprising: a step of determining a gradient of a time series of temperature measurements measured on the surface of the charging device; and a step of terminating the charging current when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a cooling period. Claim 9 A method according to claim 1, further comprising: determining a gradient of a time series of temperature measurements measured on the surface of the charging device; and reducing the power output of one or more other driver circuits in the charging device when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a cooling period. Claim 10 A method according to claim 1, comprising: determining a first gradient of a first time series of temperature measurements measured on the surface of the charging device; terminating the charging current when the first gradient of the first time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a first cooling period; determining a second gradient of a second time series of temperature measurements measured on the surface of the charging device after terminating the charging current; and reducing the power output of one or more other driver circuits in the charging device when the second gradient of the second time series of temperature measurements indicates that the surface of the charging device will be maintained above the restart temperature defined for the device being charged during a second cooling period. Claim 11 As a charging device, a driver circuit configured to drive a transmitting coil located near the surface of the charging device - the charging device is a multi-device, multi-coil wireless charger -; and a controller, wherein the controller comprises: causing the driver circuit to provide a charging current to the transmitting coil; decoding a request for lower transmitting power—the request being encoded by the charging device as a signal superimposed on the charging current—; obtaining a measured temperature of the surface of the charging device after receiving the request for lower transmitting power; estimating whether an overtemperature state exists in at least one charging device located on the surface of the charging device based on the measured temperature of the surface of the charging device, and reducing the transmitting power by reducing the amplitude of the charging current in accordance with the request for lower transmitting power when the temperature measured on the surface of the charging device is below a critical temperature; estimating whether an overtemperature state exists in at least one charging device located on the surface of the charging device based on the measured temperature of the surface of the charging device, and initiating a cooling sequence when the temperature measured on the surface of the charging device is equal to or exceeds the critical temperature—initiating the cooling sequence includes providing minimum transmitting power—, and the controller comprises: a limited period for the cooling sequence A charging device further configured to provide. Claim 12 A charging device according to claim 11, further comprising one or more sensors thermally conductively coupled to the surface of the charging device and configured to provide periodic temperature measurements of at least a portion of the surface of the charging device. Claim 13 In claim 11, the charging device, wherein the critical temperature is configured based on prior calibration performed during the charging procedure. Claim 14 A charging device according to claim 11, wherein the temperature measured on the surface of the charging device that is equal to or exceeds the critical temperature indicates that the internal temperature of the device being charged exceeds the temperature limit. Claim 15 A charging device according to claim 11, wherein the critical temperature is defined using a lookup table that associates the temperature measured at the surface of the charging device with an estimate of the internal temperature of the device being charged by the charging device. Claim 16 As a charging device, a driver circuit configured to drive a transmitting coil located near the surface of the charging device - the charging device is a multi-device, multi-coil wireless charger -; and a controller, wherein the controller comprises: causing the driver circuit to provide a charging current to the transmitting coil; decoding a request for lower transmitting power—the request being encoded by the charging device as a signal superimposed on the charging current—; obtaining a measured temperature of the surface of the charging device after receiving the request for lower transmitting power; estimating whether an overtemperature state exists in at least one charging device located on the surface of the charging device based on the measured temperature of the surface of the charging device, and reducing the transmitting power by reducing the amplitude of the charging current in accordance with the request for lower transmitting power when the temperature measured on the surface of the charging device is below a critical temperature; estimating whether an overtemperature state exists in at least one charging device located on the surface of the charging device based on the measured temperature of the surface of the charging device, and initiating a cooling sequence when the temperature measured on the surface of the charging device is equal to or exceeds the critical temperature—initiating the cooling sequence includes providing minimum transmitting power—and wherein the critical temperature is at the surface of the charging device A charging device defined using a lookup table that associates a measured temperature with an estimate of the internal temperature of a device being charged by the charging device, wherein the lookup table includes an estimate of the internal temperature for each of a plurality of device types. Claim 17 delete Claim 18 A charging device according to claim 11, wherein the controller: determines a gradient of a time series of temperature measurements measured on the surface of the charging device; and terminates the charging current when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a cooling period. Claim 19 A charging device according to claim 11, wherein the controller: determines a gradient of a time series of temperature measurements measured on the surface of the charging device; and further configured to reduce the power output of one or more other driver circuits in the charging device when the gradient of the time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the device being charged during a cooling period. Claim 20 A charging device according to claim 11, wherein the controller is further configured to: determine a first gradient in a first time series of temperature measurements measured on the surface of the charging device; terminate the charging current when the first gradient of the first time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the charging device during a first cooling period; determine a second gradient in a second time series of temperature measurements measured on the surface of the charging device after terminating the charging current; and reduce the power output of one or more other driver circuits in the charging device when the second gradient of the second time series of temperature measurements indicates that the surface of the charging device will be maintained above a restart temperature defined for the charging device during a second cooling period.

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