Detection of device removal from a surface of a multi-coil wireless charging device

PRIORITY CLAIM [0001] This application is nonprovisional patent application Ser. Application Ser. 019,245, and provisional patent application Ser. The entire contents of these applications are hereby incorporated by reference for all applicable purposes as if fully set forth below.

[0002] The present invention relates generally to wireless charging of batteries, including those of mobile computing devices, and more particularly to detecting device removal during charging operations.

[0003] Certain devices have introduced wireless charging systems that allow the internal battery to be charged without using a physical charging connection. Devices capable of wireless charging include mobile processing devices and/or communication devices. Standards such as the Qi standard developed by the Wireless Power Consortium (WPC) allow devices manufactured by one supplier to be wirelessly charged using charging equipment manufactured by a second supplier. Wireless charging standards are optimized for relatively simple configurations of devices and often provide basic charging functionality.

[0004] The continued increasing complexity and changing form factors of mobile devices require improved wireless charging capabilities. For example, faster, lower power detection techniques are available to detect and locate a chargeable device on the surface of a charging device and to detect removal or repositioning of the chargeable device during wireless charging operation. It has been demanded.

<figref num="1">FIG. 1 illustrates an example charging cell that may be provided on a charging surface provided by a wireless charging device, according to certain aspects disclosed herein.</figref><figref num="2">FIG. 2 illustrates an example arrangement of charging cells provided on a single layer of segments of a charging surface provided by a wireless charging device, according to certain aspects disclosed herein.</figref><figref num="3">FIG. 3 illustrates an example arrangement of charge cells when multiple layers of charge cells are stacked within a segment of a charging surface provided by a wireless charging device, according to certain aspects disclosed herein.</figref><figref num="4">FIG. 4 illustrates the arrangement of power transfer areas provided by the charging surface of a charging device that employs multiple layers of charging cells constructed in accordance with certain aspects disclosed herein.</figref><figref num="5">FIG. 5 illustrates a wireless transmitter that may be provided at a charging device base station, according to certain aspects disclosed herein.</figref><figref num="6">FIG. 6 illustrates a first example response to a passive ping, according to certain aspects disclosed herein.</figref><figref num="7">FIG. 7 illustrates a second example response to a passive ping, according to certain aspects disclosed herein.</figref><figref num="8">FIG. 8 shows examples of differences observed in responses to passive pings, according to certain aspects disclosed herein.</figref><figref num="9">FIG. 9 illustrates a first topology supporting matrix multiplexed switching for use in a wireless charging device adapted according to certain aspects disclosed herein.</figref><figref num="10">FIG. 10 illustrates a second topology supporting DC drive in a wireless charging device adapted according to certain aspects disclosed herein.</figref><figref num="11">FIG. 11 illustrates a multi-coil wireless charging system configured to reliably detect removal of a receiving device, according to certain aspects of the present disclosure.</figref><figref num="12">FIG. 12 is a graphical representation of certain aspects of device removal events that may be monitored in accordance with certain aspects disclosed herein.</figref><figref num="13">FIG. 13 illustrates a filtered threshold detection circuit that uses low-pass filtering to accommodate variations in charging current or tank voltage, according to certain aspects disclosed herein.</figref><figref num="14">FIG. 14 illustrates a Q-factor comparison circuit used to detect removal of a powered device, according to certain aspects disclosed herein.</figref><figref num="15">FIG. 15 illustrates use of a lookup table to detect device removal events, according to certain aspects disclosed herein.</figref><figref num="16">FIG. 16 illustrates an example procedure for using a lookup table in detecting a device removal event, according to certain aspects disclosed herein.</figref><figref num="17">FIG. 17 illustrates the use of measured quiescent or idle state transfer power consumption to detect a device removal event, in accordance with certain aspects disclosed herein.</figref><figref num="18">FIG. 18 illustrates a first example procedure for device removal detection based on measured static power consumption, according to certain aspects disclosed herein.</figref><figref num="19">FIG. 19 illustrates a second example procedure for device removal detection based on measured static power consumption, according to certain aspects disclosed herein.</figref><figref num="20">FIG. 20 illustrates a first example of using measurement slots to perform a ping procedure, according to certain aspects disclosed herein.</figref><figref num="21">FIG. 21 illustrates a second example of using measurement slots to perform a ping procedure, according to certain aspects disclosed herein.</figref><figref num="22">FIG. 22 illustrates a first example of using sensors to detect removal of a powered device during power transfer, according to certain aspects disclosed herein.</figref><figref num="23">FIG. 23 illustrates a second example of using sensors to detect removal of a powered device during power transfer, according to certain aspects disclosed herein.</figref><figref num="24">FIG. 24 illustrates a third example of using sensors to detect removal of a powered device during power transfer, according to certain aspects disclosed herein.</figref><figref num="25">FIG. 25 illustrates a fourth example of using sensors to detect removal of a powered device during power transfer, according to certain aspects disclosed herein.</figref><figref num="26">FIG. 26 illustrates a fifth example of using sensors to detect removal of a powered device during power transfer, according to certain aspects disclosed herein.</figref><figref num="27">FIG. 27 illustrates an example of an apparatus using processing circuitry that may be adapted according to certain aspects disclosed herein.</figref><figref num="28">FIG. 28 illustrates a method of operating a charging device, according to certain aspects of the present disclosure.</figref>

[0033] The detailed description set forth below in conjunction with the accompanying drawings is intended to be illustrative of various configurations and is intended to represent the only configurations in which the concepts described herein may be implemented. not intended. The detailed description includes specific details for 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 elements are shown in block diagram form in order to avoid obscuring such concepts.

[0034] Certain aspects of wireless charging systems will now be described with reference to various apparatus and methods. These apparatus and methods are described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). . These elements can be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0035] By way of example, an element, any portion of an element, or any combination of elements may be implemented with a "processing system" that includes 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, gate logic, discrete hardware circuits, and those described throughout this disclosure. Other suitable hardware configured to perform the various functions described herein are included. One or more processors within the processing system may execute software. Software includes instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc. shall be interpreted broadly regardless of whether it is called software, firmware, middleware, microcode, hardware description language, or the like. The software can reside on a processor-readable storage medium. Processor-readable storage media, also referred to herein as computer-readable media, include, for example, magnetic storage devices (eg, hard disks, floppy disks, magnetic strips), optical disks (eg, compact discs (CDs), digital versatile discs (DVDs)), Smart cards, flash memory devices (e.g. cards, sticks, key drives), NFC (Near Field Communications) tokens, random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), registers, removable disks, carrier waves, transmission lines, etc. , includes any medium suitable for storing or transmitting the software. The computer-readable medium may reside within the processing system, be external to the processing system, or be distributed among multiple entities including the processing system. A computer readable medium may be embodied in a computer program product. By way of example, a computer program product may include a computer-readable medium in packaging material. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure, depending on the particular application and overall design constraints imposed on the overall system. Will.

Overview [0036] Certain aspects of the present disclosure relate to systems, devices, and methods applicable to wireless charging devices and techniques. A charging cell consists of one or more inductive coils to provide a charging surface for the charging device, which enables the charging device to wirelessly charge one or more chargeable devices. The position of the device being charged can be detected by sensing techniques that relate the position of the device to changes in physical properties about known positions on the charging surface. Position sensing may be implemented using capacitive, resistive, inductive, contact, pressure, load, strain, and/or another suitable type of sensing.

[0037] In one aspect of the present disclosure, an apparatus includes a battery charging power supply, a plurality of charging cells arranged in a matrix, and each switch coupling a column of coils in the matrix to a first terminal of the battery charging power supply. and a second plurality of switches, each switch configured to couple a column of coils in the matrix to a second terminal of the battery charging power supply. Each charge cell in the plurality of charge cells may include one or more coils surrounding a power transfer region. The multiple charge cells can be positioned adjacent to the charging surface of the charging device such that the power transfer areas of the charge cells within the multiple charge cells do not overlap.

[0038] In some examples, the device is also referred to as a charging surface. Power can be transmitted wirelessly to a receiving device located anywhere on the surface of the device. The device can have any defined size and/or shape and can be placed regardless of any discrete placement position where charging is possible. A single charging surface can charge multiple devices at the same time. The device can track movement of one or more devices across the charging surface.

CHARGE CELLS [0039] According to certain aspects disclosed herein, a charging device can be provided with a charge surface using charge cells, where a plurality of charge cells are adjacent to the charge surface. are placed. In one example, the charging cells are arranged in one or more layers of the charging surface according to a honeycomb package configuration. A charging cell can be implemented using one or more coils, each capable of inducing a magnetic field along an axis substantially orthogonal to the charging surface adjacent to the coil. As used herein, a charge cell is an element having one or more coils, each coil being additive with respect to the electromagnetic fields generated by the other coils in the charge cell, along or in close proximity to a common axis. An element configured to generate an electromagnetic field directed toward a

[0040] In some implementations, a charge cell includes coils that are stacked and/or overlapped along a common axis such that each contributes to an induced magnetic field that is substantially orthogonal to the charge surface. In some implementations, the charge cells include coils disposed within defined portions of the charge surface that contribute to induced magnetic fields within substantially orthogonal portions of the charge surface associated with the charge cell. In some implementations, the charge cell may be configurable by supplying an activation current to a coil included in the dynamically defined charge cell. For example, the charging apparatus may comprise multiple stacks of coils distributed across the charging surface, the charging apparatus detecting the location of the device to be charged and selecting some combination of stacks of coils to be charged. can provide a charge cell adjacent to a device that In some examples, a charging cell may include or be characterized as a single coil. However, it should be understood that a charge cell may include multiple stacked coils and/or multiple adjacent coils or stacks of coils. Coils are also referred to herein as charging coils, wireless charging coils, transmitter coils, transmitting coils, power transmission coils, power transmitter coils, and the like.

[0041] Figure 1 illustrates an example charging cell 100 that may be deployed and/or configured to provide a charging surface for a charging device. As described herein, a charging surface can include an array of charging cells 100 provided on one or more substrates 106. FIG. Circuitry including one or more integrated circuits (ICs) and/or discrete electronic components can be provided on one or more substrates 106 . The circuitry may include drivers and switches used to control the current provided to the coils used to transmit power to the powered device. A circuit can be configured as a processing circuit that includes one or more processors and/or one or more controllers that can be configured to perform the specific functions disclosed herein. In some examples, some or all of the processing circuitry may be provided external to the charging device. In some examples, a power source may be coupled to the charging device.

[0042] The charging cell 100 can be provided near the outer surface area of the charging device, and one or more devices can be placed on it to be charged. The charging device may include multiple charging cells 100 . In one example, the charging cell 100 has a substantially hexagonal shape surrounding one or more coils 102, which are conductors capable of receiving sufficient current to generate an electromagnetic field in the power transfer region 104. It can be constructed using wires, or circuit board traces. In various embodiments, some coils 102 can have shapes that are substantially polygonal, including the hexagonal charging cell 100 shown in FIG. Other implementations provide coils 102 having other shapes. The shape of the coil 102 may be determined, at least in part, by manufacturing technology capabilities or limitations and/or to optimize the layout of the charging cells on a substrate 106, such as a printed circuit board. Each coil 102 may be implemented using spiral-configured wires, printed circuit board traces, and/or other connectors. Each charge cell 100 may span two or more layers separated by insulators or substrates 106 such that the coils 102 of different layers are centered on a common axis 108 .

[0043] Figure 2 illustrates an example arrangement 200 of charge cells 202 provided on a single layer segment of a charging surface of a charging device that may be adapted in accordance with certain aspects disclosed herein. The charge cells 202 are arranged according to a honeycomb package configuration. In this example, the charge cells 202 are arranged end-to-end without overlapping. This arrangement can be provided without through-holes or wire interconnections. Other arrangements are possible, including an arrangement in which the charging cells 202 partially overlap. For example, the wires of two or more coils may be interleaved to some extent.

[0044] FIG. 3 shows the arrangement of charging cells from two perspectives 300, 310 when multiple layers are stacked within segments of a charging surface that may be adapted according to certain embodiments disclosed herein. shows an example of Layers of charging cells 302, 304, 306, 308 are provided within segments of the charging surface. The charge cells within each layer of charge cells 302, 304, 306, 308 are arranged according to a honeycomb package configuration. In one example, the layers of charge cells 302, 304, 306, 308 can be formed on a printed circuit board having four or more layers. The placement of charge cells 100 can be selected to completely cover the designated charge area adjacent to the segments shown.

[0045] FIG. 4 illustrates an arrangement of power transfer regions provided in a charging surface 400 employing multiple layers of charging cells constructed in accordance with certain aspects disclosed herein. The charging surface shown consists of four layers of charging cells 402,404,406,408. In FIG. 4, each power transfer area provided by the charge cells of the first layer of charge cells 402 is labeled "L1" and each power transfer area provided by the charge cells of the second layer of charge cells 404 is labeled "L1". is labeled "L2" and the charge cell's<u style="Single">third layer 406</u>The transfer area provided by the charge cell is labeled "L3" and the charge cell's<u style="Single">fourth layer 408</u>Each power transfer region provided by a charge cell is labeled "L4".

Wireless Transmitter [0046] Figure 5 shows a wireless transmitter 500 that may be provided at the charging device base station. Controller 502 may receive the feedback signal filtered or otherwise processed by conditioning circuit 508 . A controller can control the operation of a driver circuit 504 that supplies alternating current to a resonant circuit 506 that includes a capacitor 512 and an inductor 514 . The resonant circuit 506 is also 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 is also referred to as the tank voltage.

[0047] Wireless transmitter 500 may be used by a charging device to determine if a compatible device has been placed on the charging surface. For example, the charging device can determine when a compatible device is placed on the charging surface by transmitting an intermittent test signal (active ping) through wireless transmitter 500, and resonant circuit 506 can detect or receive the encoded signal when a compatible device responds to the test signal. The charging device can be configured to activate one or more coils in at least one charging cell after receiving a response signal defined by a standard, practice, manufacturer, or application. In some instances, a compatible device responds to pings by communicating received signal strength so that the charging device can find the best charging cell to use to charge the compatible device. You may

[0048] A passive ping technique uses the voltage and/or current measured or observed at the LC node 510 to quantify the voltage of the receiving coil near the charging pad of a device adapted according to certain embodiments disclosed herein. existence can be identified. In many conventional wireless charging device transmitters, circuitry is provided to measure the voltage at the LC node 510 or to measure the current in the LC network. These voltages and currents may be monitored for power regulation purposes or to support communication between devices. In the example shown in FIG. 5, the voltage at LC node 510 is monitored, but current can additionally or alternatively be monitored to support passive pings in which short pulses are provided to resonant circuit 506. FIG. Response of resonant circuit 506 to passive ping (initial voltage V₀) is the voltage at LC node 510 (V_LC) can be expressed as follows:

(Formula 1)<img file="JP7253295B2_D0001.tif" />

[0049] According to certain aspects disclosed herein, selectively activating coils in one or more charging cells to provide optimal electromagnetic fields for charging compatible devices. can be done. In some examples, coils may be assigned to charge cells and some charge cells may overlap other charge cells. In the latter case, the optimal charging configuration can be selected at the charge cell level. In another example, a charge cell may be defined based on the placement of the device to be charged on the surface of the charging apparatus. In these other examples, the combination of coils activated at each charging event may vary. In some implementations, the charging device may include driver circuitry that can select and activate one or more cells and/or one or more predefined charging cells during a charging event.

[0050] FIG. 6 shows a first example in which a response 600 to a passive ping decays according to Equation 3. After pulse excitation at time t=0, the voltage and/or current are seen to oscillate at the resonant frequency defined by Equation 1 with a damping rate defined by Equation 3. The first cycle of oscillation is voltage level V₀starts with V_LCcontinues to decay to zero as controlled by the Q-factor and ω. The example shown in FIG. 6 represents a typical open or no load response when no object is present or near the charging pad. In FIG. 6, the value of Q-factor is assumed to be 20.

[0051] FIG. 7 shows a second example in which a response 700 to a passive ping decays according to Equation 3. After pulse excitation at time=0, the voltage and/or current are seen to oscillate at the resonance frequency defined in Eq. 1 with the damping rate defined in Eq. The first cycle of oscillation is voltage level V₀starts with V_LCcontinues to decay to zero as controlled by the Q-factor and ω. The example shown in FIG. 7 represents the load response when an object is present or nearby on the charging pad and loads the coil.<u style="Single">Figure 7</u>, the Q-factor value can be 7. V._LCis oscillating faster at response 700 than at response 600.

[0052] Figure 8 shows a set of examples in which differences in responses 800, 820, 840 are observed. A passive ping is initiated when driver circuit 504 excites resonant circuit 506 with a pulse shorter than 2.5 μs. Different types of wireless receivers and other objects placed on the transmitter produce different observable responses in the voltage at the LC node 510 or the current in the resonant circuit 506 of the transmitter. This difference is V₀may indicate the Q-factor variation of the frequency of oscillation of the resonant circuit 506 at . Table 1 shows specific examples of objects placed on the charging pad in relation to the open state.

table 1<img file="JP7253295B2_D0002.tif" />In Table 1, the Q-factor can be calculated as:

(Formula 2)<img file="JP7253295B2_D0003.tif" />where N swings from excitation to 0.5V₀is the number of cycles until the

Selective Activation of Coils [0053] According to certain aspects disclosed herein, the transmission coils in one or more charging cells are selectively activated to charge compatible devices. can provide an optimal electromagnetic field for In some examples, transmission coils are assigned to charge cells, and some charge cells may overlap other charge cells. In the latter case, the optimal charging configuration can be selected at the charge cell level. In other examples, charging cells may be defined based on the placement of devices to be charged on the charging surface. In these other examples, the combination of coils activated at each charging event may vary. In some implementations, the charging device may include driver circuitry that can select and activate one or more cells and/or one or more predefined charging cells during a charging event.

[0054] FIG. 9 illustrates a first topology 900 supporting matrix multiplexed switching for use in a wireless charging device adapted according to certain aspects disclosed herein. A wireless charging device can select one or more charging cells 100 to charge a powered device. Charge cells 100 that are not in use can be disconnected from the current flow. A relatively large number of charge cells 100 can be used in the honeycomb package configuration shown in FIG. 2 requiring a corresponding number of switches. According to certain aspects disclosed herein, charging cells 100 are logically arranged in a matrix 908 having a plurality of cells connected to two or more switches that enable powering of a particular cell. can be The illustrated topology 900 provides a two-dimensional matrix 908 whose dimensions can be represented by X and Y coordinates. A first set of switches 906 each selectively connect a first terminal of each cell in a column of cells to a wireless transmitter and/or receiver circuit 902 that provides current for activating the coil during wireless charging. configured to be coupled to A second set of switches 904 are each configured to selectively couple a second terminal of each cell in the column of cells to the wireless transmitter and/or receiver circuitry 902 . A cell is active when both terminals of the cell are coupled to the wireless transmitter and/or receiver circuit 902 .

[0055] The use of matrix 908 can significantly reduce the number of switch components required to operate a network of tuned LC circuits. For example, N individually connected cells require at least N switches, whereas a two-dimensional matrix 908 with N cells can operate with N switches. The use of matrix 908 can provide significant cost savings and reduce circuit and/or layout complexity. In one example, a 9-cell implementation can be implemented in a 3×3 matrix 908 using 6 switches, saving 3 switches. In another example, a 16-cell implementation can be implemented in a 4x4 matrix 908 using 8 switches, saving 8 switches.

[0056] In operation, at least two switches are closed to actively couple one coil to the radio transmitter and/or receiver circuit 902. To facilitate connection of multiple coils to the radio transmitter and/or receiver circuit 902, multiple switches can be closed at once. Multiple switches can be closed to enable a mode of operation that drives multiple transmit coils when transferring power to a powered device, for example.

[0057] FIG. 10 illustrates a second topology 1000 in which each coil or charge cell is individually driven and/or directly driven by a driver circuit 1002, according to certain aspects disclosed herein. Driver circuit 1002 may be configured to select one or more coils or charging cells 100 from coil group 1004 to charge a powered device. It will be appreciated that the concepts disclosed herein with respect to charging cell 100 are also applicable to selective activation of individual coils or coil stacks. Charging cells 100 that are not used receive no current. A relatively large number of charge cells 100 can be used and a switching matrix can be used to drive individual coils or groups of coils. In one example, a first switching matrix configures the connections that define the charge cells or coils used during a charging event, and a second switching matrix (see, for example, FIG. 9) configures the charge cells and/or selections. can be used to activate the selected coil group.

DEVICE REMOVAL DETECTION FROM MULTI-COIL WIRELESS CHARGER [0058] Referring now to FIG. It can be configured for reliable detection. Any and/or unexpected removal of a powered device can damage other powered devices 1108 in addition to the potential loss of detection efficiency of nearby devices 1108 . A multi-coil wireless charging system 1100 includes multiple transmission coils 1104₁~1104_nA charging surface 1102 is provided that includes: In the illustrated example, the power receiving device 1106 is connected to the nth transmission coil (transmission coil 1104_n) while receiving the charging flux.

[0059] In some examples, the charging surface 1102 remains connected to the transmission coil 1104 after the powered device 1106 is removed._ncontinue to supply charging current to An approaching device 1108 may be placed on the charging surface 1102 while this charging current is flowing. The charging current is typically configured based on the capabilities of the powered device 1106, which may differ from the capabilities of the proximate device 1108. If the approaching device 1108 is not designed to handle the level of induced current directed to the original powered device 1106, damage to the proximity device 1108 will occur.

[0060] Certain aspects of the present disclosure enable the multi-coil wireless charging system 1100 to quickly and reliably detect removal of the powered device 1106 from the charging surface 1102. When the multi-coil wireless charging system 1100 detects removal of the powered device 1106, the active transmit coil 1104_ncan stop the flow of charging current to When the multi-coil wireless charging system 1100 detects removal of the powered device 1106 and stops charging current, the charging surface 1102 can be configured to detect objects, including the approaching device 1108 .

[0061] According to certain aspects of the present disclosure, removal of the powered device 1106 removes the charging circuit or the one or more transmission coils 1104.₁~1104_ncan be detected by monitoring certain characteristics of In a particular example, removal of power receiving device 1106 may cause transmission coil 1104_nand a receiving coil in the receiving device 1106 can be detected based on changes in the measured electrical quantity that can result from changes in the electromagnetic coupling.

[0062] In one example, DICE (Dynamic Inferred Coupling Estimation) can be used to detect coupling quality in real time. DICE may involve evaluating the ratio of reactive power to real power in a circuit containing a transmission coil and a series resonant capacitor. The amount of reactive power stored in a transmitter's inductor-capacitor (LC) circuit is greatly affected by the coupling coefficient. The coupling coefficient defines the ratio of mutual inductance to leakage inductance of the LC circuit of the radio transmitter. For example, the leakage inductance in the LC circuit of a radio transmitter can be expressed as:

(Formula 3)<img file="JP7253295B2_D0004.tif" />where L_Txrepresents the self-inductance of the transmission coil and k represents the coupling coefficient. Decreased coupling reduces the coupling coefficient and increases the leakage inductance, thus increasing the reactive energy stored in the leakage inductance of the transmitter. The energy stored in the leakage inductance does not contribute to power transfer, and the energy stored in the leakage inductance causes the LC node voltage to rise.

[0063] One or more transmission coils 1104₁~1104_nA particular aspect of the coupling between and the powered device 1106 may be characterized by the voltage measured at the LC node. Voltage measurements at the LC node are also possible for other reasons. In some examples, the LC node voltage can be monitored as an overvoltage indicator used to protect power electronics and resonant capacitors. In one example, the measurement circuit includes a voltage comparator configured to detect voltages above a threshold level. According to certain aspects disclosed herein, measurement circuitry can be added or existing measurement circuitry can be used to quantify or compare voltages at the LC nodes that vary directly with coupling quality. .

[0064] FIG. 12 is a graphical representation 1200 of certain aspects of a device removal event that may be monitored in accordance with certain aspects disclosed herein. The two curves 1202 , 1204 represent states of electrical quantities that can be measured by the multi-coil wireless charging system 1100 .

[0065] A first curve 1202 plots one or more active transmit coils 1104 to charge a powered device 1106.₁~1104_nrepresents the magnitude of the current flowing through A powered device 1106 is initially placed near the charging surface 1102 and is receiving power wirelessly. After that, the powered device 1106 begins to move away from the charging surface 1102, which is the first time point 1206(t₁) and the transmit coil 1104 where the receiving device 1106 is active.₁~1104_nA second point in time 1208 (t₂). As shown in FIG. 12, the charging current is expected to drop when the powered device 1106 is removed. A first curve 1202 has a step between the initial level of charging current and the level of charging or quiescent current after the powered device 1106 is removed. Given the inverse-square relationship associated with electromagnetic coupling as the distance between the transmitter and receiver increases, even if the powered device 1106 is removed at a moderate rate, the charging current will drop sharply. Observed.

[0066] The second curve 1204 shows the one or more active transmit coils 1104 used to wirelessly charge the powered device 1106.₁~1104_nrepresents the magnitude of the tank voltage measured at the LC node in the resonant circuit containing The powered device 1106, initially placed near the charging surface 1102 to wirelessly receive power, begins to move away from the charging surface 1102, which is at a first time point 1206(t₁) and the transmit coil 1104 where the receiving device 1106 is active.₁~1104_nA second point in time 1208 (t₂). As shown in FIG. 12, the tank voltage can be expected to increase with the impedance of the resonant circuit caused by the power receiving device 1106 being removed. A second curve 1204 has a step between the initial level of the tank voltage and the level of the tank voltage after the powered device 1106 is removed. Given the inverse-square relationship associated with electromagnetic coupling as the distance between the transmitter and receiver increases, even if the powered device 1106 is removed at a moderate rate, the impedance and tank voltage will change rapidly. An increase can be observed.

[0067] According to certain aspects of the present disclosure, one or more active transmit coils 1104₁~1104_nThe charging current and/or tank voltage provided to the can be monitored during power transfer. When the current or voltage step exceeds the threshold difference value, or when the current rate of change (di/dt) or voltage change rate (dv/dt) exceeds the threshold rate of change, the charge current is can be discontinued. The threshold difference value and/or the threshold change rate can be preset at system initialization and/or during manufacturing and assembly, depending on the application. In some implementations, the threshold difference value and/or the threshold rate of change is determined by the transmission coil 1104 used for wireless₁~1104_ncharging configuration that identifies the number of charging currents, charging current size, and/or may be dynamically configured based on the structure and internal configuration of the powered device 1106 .

[0068] In some examples, fluctuations in charging current or tank voltage may be observed when the powered device 1106 is not removed. For example, the charging current or tank voltage may change due to vibration or slippage of the powered device 1106 or charging surface 1102, physical instability caused by movement of the multi-coil wireless charging system 1100, or changes in temperature or drift in the power supply output. . In certain implementations, low-pass filtering may be employed to accommodate such variations in charging current or tank voltage.

[0069] FIG. 13 illustrates a filtered threshold detection circuit 1300 that employs low-pass filtering to accommodate variations in charging current or tank voltage that are not due to movement of the powered device 1106. be. FIG. 13 includes graph 1320 illustrating certain aspects related to the operation of filtered threshold detection circuit 1300. FIG. In the illustrated example, the filtered threshold detection circuit 1300 detects one or more active transmit coils 1104 used to charge the powered device 1106.₁~1104_nreceives an input signal 1310 representing the charging current flowing through the An input signal 1310 is provided to a low pass filter 1302, where step changes in the input signal 1310 can be slowed and/or the rate of change of the input signal 1310 can be slowed. The comparator circuit 1304 compares the output 1312 of the low pass filter 1302 with a threshold signal 1314 generated from the input signal 1310 using a scaling factor 1308 or offset based on the previous state of the output 1316 of the comparator circuit 1304 . Threshold signal 1314 may be generated by feedback circuit 1306 to provide hysteresis for filtered threshold detection circuit 1300 . The threshold signal 1314 provides a reference point 1330 that allows the comparison circuit 1304 to reliably indicate removal of the powered device 1106 . Low pass filter 1302 may be configured with a filter constant configured such that normal small variations in current 1332 do not cause the device to indicate rejection.

[0070] A first curve 1322 shows one or more active transmit coils 1104 for charging a powered device 1106.₁~1104_nrepresents the magnitude of the current flowing through Powered device 1106 is initially placed near charging surface 1102 and is receiving power wirelessly. A second curve 1324 represents a threshold used to determine a step change in charging current indicative of a device removal event. Powered device 1106 begins to move away from charging surface 1102, which is a first time point 1326(t₁) and the transmit coil 1104 where the receiving device 1106 is active.₁~1104_nA second point in time 1328 (t₂).

[0071] The charging current drops when the powered device 1106 is removed, resulting in a step between the initial level of the charging current and the level of the charging or quiescent current after the powered device 1106 is removed. . The threshold signal 1314 ensures that large step changes in charging current (or large increases in tank voltage) exceed the threshold.

[0072] In another aspect of this disclosure, detection of removal of powered device 1106 may be accomplished using slot-based techniques. In one example, time slots are provided in which the charging current is briefly interrupted to allow measurement and/or interrogation of one or more sensors.

[0073] FIG. 14 shows a Q-factor comparison circuit 1400 and corresponding timing diagram 1420 illustrating detection of removal of the powered device 1106 during a measurement slot 1424. FIG. Timing diagram 1420 illustrates one or more active transmit coils 1104 when charging surface 1102 of multi-coil wireless charging system 1100 is configured to charge powered device 1106 .₁~1104_nIt includes a curve 1422 representing the magnitude of the charging current flowing through. Measurement slots 1424 may be provided periodically or in response to detecting a step change in the magnitude of charging current or tank voltage. During this measurement slot 1424, a slotted Q-factor test can be performed. A measurement slot 1424 may be provided when the multi-coil wireless charging system 1100 suspends or terminates charging current. In one example, measurement slot 1424 has a maximum duration of 100 microseconds (μs). Energy stored in a resonant circuit decays at a rate determined in part by the resonant circuit's Q-factor. The Q-factor of the resonant circuit is determined by the specific active transmission coil 1104 on the charging surface 1102.₁~1104_n, and the receiving coil of the powered device 1106.

[0074] A slotted Q-factor test is performed by using the transmission coil 1104 with the multi-coil wireless charging system 1100 active.₁~1104_nA first point in time 1426(t₁). The magnitude of the current in the resonant circuit decays 1428 at a rate determined by the Q-factor of the resonant circuit. In one example, Q-factor 1402 can be calculated and compared with reference Q-factor 1404 using comparator 1406 . The reference Q-factor 1404 is the transmission coil 1104 with the receiving device active.₁~1104_nmay correspond to the Q-factor calculated when not electromagnetically coupled to

[0075] In some implementations, the filtered threshold detection circuit 1300 may be used to compare the calculated Q-factor to a threshold Q-factor. In some implementations, a measurement slot 1424 is periodically provided to allow slotted Q-factor testing to be used to detect the presence of foreign objects along with device removal events.

[0076] Another aspect of this disclosure relates to removal detection of powered device 1106 using thresholds and other parameters held in a lookup table. For example, lookup tables can be used to hold measurements of charging current, tank voltage, Q-factor, and other characteristics of the multi-coil wireless charging system 1100 . In some implementations, the lookup table may hold thresholds and other parameters for different charging configurations. Each charging configuration has a transmission coil 1104 used to charge a powered device 1106.₁~1104_nand transmission coil 1104₁~1104_ncan be defined as a current distribution between For example, one or more charging configurations may concentrate the magnetic flux at a particular location or transfer coil 1104₁~1104_ndifferent transmission coils 1104₁~1104_ncan define the phase offset of the current provided to . Depending on the function, location, orientation, state of charge, and/or other characteristics of powered device 1106, one or more charging configurations can be provided. The use of lookup tables can improve the efficiency of the detection circuitry and processes used to determine if the powered device 1106 has been removed.

[0077] FIG. 15 includes graphs 1500, 1520 that illustrate the use of lookup tables to detect device removal events that may be monitored in accordance with certain aspects disclosed herein. In one example, a lookup table (LUT) may hold information identifying a known static or "empty" power and/or known current draw for a charging configuration. The multi-coil wireless charging system 1100 compares the measured power, voltage, and/or current after a step event is detected to quiescent power, voltage, and/or current thresholds held in lookup tables or other correspondences. can be compared with the value This comparison can indicate whether the step event corresponds to a load change or device removal. A change in load may occur when the powered device dumps the load. The lookup table is for receive coils and more transmit coils 1104₁~1104_nOne or more transmission coils 1104 that are not electromagnetically coupled to other objects that can affect the resonant frequency or resonant Q-factor of the resonant circuit containing₁~1104_nmay include static power, voltage and/or current values measured for In some implementations, the lookup table may be populated with values measured at various charging configurations. In some implementations, the lookup table may be populated during a system configuration or calibration procedure.

[0078] The first graph 1500 shows an example where the thresholds 1506, 1508 specified in the lookup table reliably indicate that the powered device 1106 has been removed. A second graph 1520 shows an example where the thresholds 1526, 1528 held in the lookup table reliably indicate that a change in load has occurred. A first curve 1502 , 1522 shows one or more active transmission coils 1104 for charging the powered device 1106 .₁~1104_nrepresents the magnitude of the current flowing through A powered device 1106 is initially placed near the charging surface 1102 and is receiving power wirelessly. The powered device 1106 then begins to move away from the charging surface 1102, which is the first time point 1512, 1532(t₁) and leave until the charging current received by the powered device 1106 is a reduced power corresponding to the drop-off. The first curves 1502, 1522 each include a step 1510, 1530 between the initial level of charging current and the level of charging current after the powered device 1106 is removed.

[0079] In one aspect of the present disclosure, the charging current magnitude measured after the step 1510, 1530 is compared to current thresholds 1508, 1528 (or reference quiescent current levels) obtained from a lookup table. In one example, the multi-coil wireless charging system 1100 can terminate charging current based on the difference between the charging current level after the steps 1510, 1530 and the reference quiescent current level or current thresholds 1508, 1528. In the example shown in the first graph 1500, the multi-coil wireless charging system 1100 determines whether the charging current level is within a set range that includes the reference quiescent current level or the current threshold calculated using the reference quiescent current level. Charging current can be terminated when less than 1508,1528. In the example shown in the second graph 1520, the multi-coil wireless charging system 1100 continues to deliver charging current when the charging current level is greater than the current thresholds 1508, 1528 by an amount indicative of the occurrence of a load change event. You may

[0080] The second curves 1504, 1524 of the graphs 1500, 1520 show the one or more active transmission coils 1104₁~1104_nrepresents the magnitude of the tank voltage measured across the resonant circuit containing A powered device 1106 is initially placed near the charging surface 1102 and is receiving power wirelessly. The powered device 1106 then begins to move away from the charging surface 1102, which is the first time point 1512, 1532(t₁) and move away until the power received by the powered device 1106 is reduced power corresponding to the increased tank voltage. Each of the second curves 1504, 1524 includes a step 1510, 1530 between the initial level of the tank voltage and the level of the tank voltage after the power receiving device 1106 is removed.

[0081] In one aspect of the present disclosure, the tank voltage magnitudes measured after the steps 1510, 1530 are compared to reference quiescent tank voltages or voltage thresholds 1506, 1526 obtained from lookup tables. The multi-coil wireless charging system 1100 can terminate charging current based on the difference between the tank voltage level after the step 1510,1530 and the reference quiescent tank voltage or voltage thresholds 1506,1526. In the example shown in the first graph 1500, the multi-coil wireless charging system 1100 terminates charging current when the tank voltage level is within a set range that includes the quiescent tank voltage or is greater than the voltage thresholds 1506, 1526. can do. In the example shown in the second graph 1520, the multi-coil wireless charging system 1100 may continue to deliver charging current when the tank voltage is below voltage thresholds 1506, 1526 indicating the occurrence of a load change event. .

[0082] FIG. 16 is a flowchart 1600 illustrating an example procedure based on the example shown in FIG. This procedure can be performed with the multi-coil wireless charging system 1100 . At block 1602, the multi-coil wireless charging system 1100 may begin providing charging current to the powered device 1106 according to the charging configuration. The multi-coil wireless charging system 1100 may continue charging until the multi-coil wireless charging system 1100 detects a step change in the measurement at block 1604 . In one example, the measurement may represent the magnitude of the charging current. In another example, the measurements may represent tank voltage. At block 1606, the multi-coil wireless charging system 1100 measures the value after the step. At block 1608, the multi-coil wireless charging system 1100 may compare the measurements to thresholds stored in a lookup table. The threshold can be calculated from idle or static values. A relationship between the measured value and the threshold value may indicate whether the step change in measured value is the result of removal of the powered device 1106 . If the multi-coil wireless charging system 1100 determines at block 1610 that the step change is associated with a device removal event, at block 1612 the multi-coil wireless charging system 1100 may terminate the charging current. If the multi-coil wireless charging system 1100 determines at block 1610 that the step change is not related to a device removal event, then at block 1604 the process may continue.

[0083] FIG. 17 illustrates the measured static power consumption, or pre-configured or pre-measured idle power consumption, maintained in a lookup table for detecting device removal events in accordance with certain aspects disclosed herein. 17 is a graph 1700 illustrating the use of transmission power consumption values; In one aspect, power transfer measurements are obtained during an initialization interval period 1702 that may be associated with a ping procedure. Curve 1710 represents power or current transfer from multi-coil wireless charging system 1100 to powered device 1106 . In one example, measured power transfer values that characterize minimum or static power transfer conditions can be used to set a known operating point for the multi-coil wireless charging system 1100 . A known operating point may be used to define a threshold for detecting device removal. The latter threshold is also referred to herein as measurement threshold 1716 . In another aspect, the threshold for detecting device removal can be obtained from a lookup table. The latter threshold is also referred to herein as the LUT threshold 1718. LUT thresholds 1718 may be calculated or measured during system initialization, assembly, or calibration procedures. In one example, LUT threshold 1718 can be calculated or measured when no rechargeable device or other object is placed on or near charging surface 1102 .

[0084] Curve 1710 may correspond to charging current at which power is transferred from multi-coil wireless charging system 1100 to powered device 1106. FIG. After initial detection and/or configuration of powered device 1106 , minimum power transfer level 1712 is specified and/or used to set measurement threshold 1716 . A power transfer period 1704 follows. This power transfer period 1704 continues until an event 1706 is detected indicating that the level of power transfer has dropped a step. In the illustrated example, the level of power transfer drops to a low level 1714, which may be above or below the threshold used to identify device removal. Thresholds can be selected from measurement thresholds 1716 or LUT thresholds 1718 . The multi-coil wireless charging system 1100 can initiate a measurement slot 1708 to establish or confirm that device removal has occurred. During the measurement slot 1708, the multi-coil wireless charging system 1100 can measure static power consumption and compare it to a selected threshold. After the multi-coil wireless charging system 1100 determines that the powered device 1106 has been removed, the charging current can be discontinued. After the multi-coil wireless charging system 1100 determines that the powered device 1106 has not been removed, it can continue power transfer at the low level 1714.

[0085] Figure 18 is a flowchart 1800 illustrating a first example device removal detection procedure based on measured static power consumption. This procedure can be performed with the multi-coil wireless charging system 1100 . At block 1802 , the multi-coil wireless charging system 1100 may detect the presence of a powered device 1106 placed on or near the charging surface 1102 . During the initial configuration interval period 1702, the multi-coil wireless charging system 1100 can interrogate and/or negotiate with the powered device 1106 to generate a charging configuration. At block 1804, the multi-coil wireless charging system 1100 activates the one or more active transmission coils 1104.₁~1104_ncan provide quiescent current to and measure quiescent power consumption. Multi-coil wireless charging system 1100 can use the measured static power consumption to establish measurement threshold 1716 . In one example, measurement thresholds 1716 may be stored in non-volatile memory such as random access memory (RAM) or register-based memory.

[0086] A power transfer period 1704 begins, during which the multi-coil wireless charging system 1100 activates the active transfer coils 1104 to enable power transfer to the powered device 1106 according to the charging configuration.₁~1104_ncan provide charging current to The multi-coil wireless charging system 1100 may continue charging until the multi-coil wireless charging system 1100 detects a step change in the measured power consumption at block 1806 . In one example, the measured power consumption can be represented by the magnitude of the charging current. In another example, the measured power consumption can be represented by tank voltage. At block 1808, the multi-coil wireless charging system 1100 may provide a measurement slot 1708 as the charging current decreases to a quiescent level. Multi-coil wireless charging system 1100 can measure power consumption during measurement slot 1708 . At block 1810 , multi-coil wireless charging system 1100 may compare the measured static power consumption to measurement threshold 1716 . A relationship between the measured static power consumption and the measurement threshold 1716 may indicate whether the step change in power consumption is the result of removal of the powered device 1106 . If the multi-coil wireless charging system 1100 determines at block 1812 that the step change is associated with a device removal event, at block 1814 the multi-coil wireless charging system 1100 may terminate charging current. If the multi-coil wireless charging system 1100 determines at block 1812 that the step change is not related to the device removal event,<u style="Single">block 1806</u>can continue the process.

[0087] Figure 19 is a flowchart 1900 illustrating a second example procedure for device removal detection based on measured static power consumption. This procedure can be performed with the multi-coil wireless charging system 1100 . At block 1902 , the multi-coil wireless charging system 1100 may detect the presence of a powered device 1106 placed on or near the charging surface 1102 . During the initial configuration interval period 1702, the multi-coil wireless charging system 1100 can interrogate and/or negotiate with the powered device 1106 to generate a charging configuration.

[0088] A power transfer period 1704 begins, during which the multi-coil wireless charging system 1100 has one or more active transfer coils 1104 configured to wirelessly transfer power to the powered device 1106 according to the charging configuration.₁~1104_ncan provide charging current to The multi-coil wireless charging system 1100 may continue charging until the multi-coil wireless charging system 1100 detects a step change in measured power consumption at block 1904 . In one example, the measured power consumption can be represented by the magnitude of the charging current. In another example, the measured power consumption can be represented by tank voltage. At block 1906, the multi-coil wireless charging system 1100 can provide a measurement slot 1708 as the charging current decreases to a quiescent level. Multi-coil wireless charging system 1100 can measure power consumption during measurement slot 1708 . At block 1908 , the multi-coil wireless charging system 1100 may compare the measured static power consumption with LUT thresholds 1718 . LUT thresholds 1718 may be pre-measured or pre-calculated based on static (empty coil) power consumption. Pre-measured or pre-calculated power consumption can be maintained in a lookup table stored in non-volatile memory such as flash memory. A relationship between measured static power consumption and LUT threshold 1718 may indicate whether a step change in power consumption is the result of removal of powered device 1106 . If the multi-coil wireless charging system 1100 determines at block 1910 that the step change is associated with a device removal event, at block 1912 the multi-coil wireless charging system 1100 may terminate charging current. If the multi-coil wireless charging system 1100 determines at block 1910 that the step change is not related to the device removal event, then at block 1904 the process may continue.

[0089] FIG. 20 is a graph 2000 illustrating the use of measurement slots to perform a ping procedure that can determine whether a powered device 1106 is resting on or near a charging surface 1102. FIG. Ping procedures may include active and/or passive pings. Ping procedures may include analog and/or digital pings. Initial configuration interval period 2002 may be provided after a device or object is detected on or near charging surface 1102 . A ping procedure may be performed within the initial configuration interval period 2002 to determine if the detected object is a rechargeable object and to determine an appropriate charging configuration for the rechargeable object.

[0090] Curve 2010 represents power transfer from multi-coil wireless charging system 1100 to powered device 1106. FIG. During the power transfer period 2004, an event 2006 may be detected indicating a step drop in the power transfer level. The multi-coil wireless charging system 1100 can initiate a measurement slot 2008 to establish or confirm a device removal event. During the measurement slot 2008, the multi-coil wireless charging system 1100 terminates charging current so that a ping procedure can be used to determine if the powered device 1106 has been removed. After the multi-coil wireless charging system 1100 determines that the powered device 1106 has been removed, the charging current can be discontinued. After the multi-coil wireless charging system 1100 determines that the powered device 1106 has not been removed, it can continue power transfer at the lower level 2012.

[0091] Figure 21 is a flowchart 2100 illustrating an example method for device removal detection based on a ping procedure performed during a measurement slot. This method can be performed in the multi-coil wireless charging system 1100. At block 2102 , the multi-coil wireless charging system 1100 may detect the presence of a powered device 1106 placed on or near the charging surface 1102 . During the initial configuration interval period 2002, the multi-coil wireless charging system 1100 can interrogate and/or negotiate with the powered device 1106 to generate a charging configuration.

[0092] A power transfer period 2004 begins, during which the multi-coil wireless charging system 1100 has one or more active transfer coils 1104 configured to wirelessly transfer power to the powered device 1106 according to the charging configuration.₁~1104_ncan provide charging current to The multi-coil wireless charging system 1100 may continue charging until the multi-coil wireless charging system 1100 detects a step change in measured power draw, current, or tank voltage at block 2104 . At block 2106, the multi-coil wireless charging system 1100 can provide measurement slots 2008 in which one or more ping procedures can be performed to determine if the step change is the result of removal of the powered device 1106. If the multi-coil wireless charging system 1100 determines at block 2108 that the step change is associated with a device removal event, at block 2110 the multi-coil wireless charging system 1100 may terminate charging current. If the multi-coil wireless charging system 1100 determines at block 2108 that the step change is not related to a device removal event, then at block 2104 the process may continue.

Detecting Device Removal Using Sensors [0093] According to certain aspects of the present disclosure, the presence, position, and/or orientation of a powered device can be detected by, for example, capacitance, resistance, inductance, contact, pressure, temperature, , load, strain, and/or other suitable types of sensing, including detecting differences or changes in position sensing techniques. This position sensing can be used to determine the presence or location of the object or device being charged. Position sensing can also be used to detect removal of the powered device during power transfer from the charging surface.

[0094] FIG. 22 illustrates a first example charging surface 2200 of a wireless charging device that includes one or more sensors 2202 that can detect removal of a powered device during power transfer from the charging surface 2200. FIG. In this example, sensor 2202 may include a capacitive, inductive, or Hall effect sensing element configured to detect the presence of a device. In some implementations, the sensing elements may be adjacent charging coils (LP1-LP18) provided on charging surface 2200. FIG. In some implementations, the sensing elements may be adjacent to individual charging coils or groups of charging coils. In certain implementations, charging zones may be identified on charging surface 2200 and sensing elements may define or monitor the outer limits of each charging zone.

[0095] The sensor 2202 can also be used to detect a change indicative of removal of the powered device from the charging surface 2200. In some implementations, sensor 2202 can support or enhance removal detection techniques based on charging current, tank voltage, and/or power consumption measurements. Use of sensor 2202 can improve reliability, efficiency, and reduce power consumption and processor load.

[0096] FIG. 23 illustrates one or more sensors 2312 that can be used to detect device removal.₁~2312_nand/or 2314₁~2314_n23 shows a second example of a charging surface 2300 of a wireless charging device including a . Sensor 2312₁~2312_nand/or 2314₁~2314_ncan measure deformation, load, and/or weight caused by devices or objects placed on or near charging surface 2300 . sensor 2312₁~2312_nand/or 2314₁~2314_ncan be configured to measure deformation as mechanical strain, which can quantify the displacement between two points on a surface. In one example, transmitter coil 2304₁~2304_nand the circuit board 2302, the sensor 2312₁~2312_nis the transmitter coil 2304₁~2304_nand the total weight of the device or object placed on or near the charging surface 2300 can provide a corresponding measurement. The weight of the device or object can be calculated from the total weight, or the change in total weight can be used to indicate placement or removal of the device or object. In another example, the outer surface of charging surface 2300 and transmitter coil 2304₁~2304_nSensor 2314 placed above₁~2314_ncan provide measurements corresponding to deformation of the outer surface due to the weight or shape of objects placed on or near charging surface 2300 .

[0097] Sensor 2312₁~2312_nand/or 2314₁~2314_ncan be used to detect a change indicative of removal of powered device 2306 from charging surface 2300 . In some implementations, sensor 2312₁~2312_nand/or 2314₁~2314_ncan support or enhance removal detection techniques based on charging current, tank voltage, and/or power consumption measurements. Sensor 2312₁~2312_nand/or 2314₁~2314_ncan be used to improve reliability and efficiency while reducing power consumption and processor load.

[0098] FIG. 24 illustrates one or more sensors 2412 used to detect removal of the device.₁~2412_n24 shows a third example of a charging surface 2400 of a wireless charging device including a . Sensor 2412₁~2412_ncan measure small changes in motion or vibration that occur when a powered device 2406 or other object is lifted or otherwise removed from the charging surface 2400 . In one example, sensor 2412₁~2412_nis the transmitter coil 2404₁~2404_nand the circuit board 2402 .

[0099] In some implementations, sensor 2412₁~2412_ncan support or enhance removal detection techniques based on charging current, tank voltage, and/or power consumption measurements. Sensor 2412₁~2412_ncan be used to improve reliability and efficiency while reducing power consumption and processor load.

[0100] FIG. 25 illustrates one or more devices 2504 that may be used to detect device removal.₁~2504₄and/or 2506₁~2506₄of wireless charging devices including<u style="Single">charging surface 2500</u>shows a fourth example of Device 2504₁~2504₄and/or 2506₁~2506₄may include infrared and/or ultrasonic transmission and sensing devices positioned flush with the outer surface of charging surface 2500 . In the illustrated example, transmitter 2504₁~2504₄but an infrared or ultrasonic beam sensing device 2506₁~2506₄turn to the set of Device 2504₁~2504₄and/or 2506₁~2506₄One or more beams can be blocked once a powered device 2502 is placed on the charging surface 2500 between a corresponding pair of . One or more sensing devices 2506₁~2506₄can detect the transmitted beam.

[0101] In some implementations, device 2504₁~2504₄and/or 2506₁~2506₄can support or enhance removal detection techniques based on charging current, tank voltage, and/or power consumption measurements. Device 2504₁~2504₄and/or 2506₁~2506₄can be used to improve reliability and efficiency while reducing power consumption and processor load. In some implementations, a transmitting and/or sensing device 2504₁~2504₄and/or 2506₁~2506₄Increasing the number can improve the resolution of the device position, which can be expressed in X and Y coordinates.

[0102] FIG. 26 illustrates one or more sensing devices 2604 that can be used to detect device removal.₁~2604₅26 shows a fifth example of a charging surface 2600 of a wireless charging device including a . sensing device 2604₁~2604₅may include infrared and/or ultrasonic combined transmitters and sensors. sensing device 2604₁~2604₅can be co-planar with the outer surface of charging surface 2600 . In the illustrated example, sensing device 2604₁~2604₅is configured to emit an infrared or ultrasonic beam and sense characteristics of the beam's reflection. One or more beams may be reflected by powered device 2602 placed on charging surface 2600 . sensing device 2604₁~2604₅can detect phase changes, reflection angles, and other characteristics of the reflected beam, thereby allowing detection of the powered device 2602 . Removing the powered device 2602 either results in the loss of the reflected beam or changes the characteristics of the reflected beam.

[0103] In some implementations, the sensing device 2604₁~2604₅can support or enhance removal detection techniques based on charging current, tank voltage, and/or power consumption measurements. Sensing Device 2604₁~2604₅can be used to improve reliability and efficiency while reducing power consumption and processor load. In some implementations, the sensing device 2604₁~2604₅Increasing the number of can improve the resolution of the device position, which can be expressed in X and Y coordinates. In some implementations, the sensing device 2604₁~2604₅is the sensing device 2604₁~2604₅and the powered device 2602 , allowing the two sensors to pinpoint the exact location of the powered device 2602 .

Example Processing Circuit [0104] Figure 27 shows an example hardware implementation of an apparatus 2700 that can be incorporated into a charging apparatus or power receiving device that enables wireless charging of a battery. In some examples, device 2700 can perform one or more functions disclosed herein. According to various aspects of the present disclosure, an element, any portion of an element, or any combination of elements as disclosed herein can be implemented using processing circuitry 2702 . Processing circuitry 2702 may include one or more processors 2704 controlled by some combination of hardware and software modules. Examples of processors 2704 include microprocessors, microcontrollers, digital signal processors (DSPs), SoCs, ASICs, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, sequencers, gate logic, discrete hardware Circuitry and other suitable hardware configured to perform various functions described throughout this disclosure are included. One or more processors 2704 may include specialized processors that perform specific functions and may be configured, enhanced, or controlled by one of the software modules 2716 . The one or more processors 2704 may be configured by a combination of software modules 2716 loaded during initialization, and may be configured by loading and unloading one or more software modules 2716 during operation. .

[0105] In the depicted example, the processing circuitry 2702 may be implemented with a bus architecture, generally represented by bus 2710. As shown in FIG. Bus 2710 may include any number of interconnecting buses and bridges, depending on the particular application of processing circuitry 2702 and overall design constraints. Bus 2710 couples various circuits including one or more processors 2704 and storage 2706 to each other. Storage 2706 can include memory devices and mass storage devices, and is also referred to herein as computer-readable media and/or processor-readable media. Storage 2706 may include temporary and/or non-transitory storage media.

[0106] Bus 2710 may also couple various other circuits such as timing sources, timers, peripherals, voltage regulators, and power management circuits. Bus interface 2708 may provide an interface between bus 2710 and one or more transceivers 2712 . In one example, transceiver 2712 may enable apparatus 2700 to communicate with charging and powered devices according to standards-defined protocols. Depending on the nature of device 2700, a user interface 2718 (eg, keypad, display, speaker, microphone, joystick) may be provided and communicatively coupled to bus 2710 either directly or via bus interface 2708.

[0107] Processor 2704 is responsible for general processing, including managing bus 2710 and executing software stored in computer-readable media, including storage 2706. In this regard, processing circuitry 2702, including processor 2704, can be used to implement any of the methods, functions, and techniques disclosed herein. Storage 2706 can be used to store data that is manipulated by processor 2704 when executing software configured to implement any one of the methods disclosed herein. can be

[0108] One or more processors 2704 in the processing circuitry 2702 are capable of executing software. Software includes instructions, instruction sets, codes, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, algorithms. etc., and shall be construed broadly regardless of whether they are referred to as software, firmware, middleware, microcode, hardware description languages, or the like. The software may reside in computer readable form in storage 2706 or on an external computer readable medium. External computer-readable media and/or storage 2706 may include non-transitory computer-readable media. Non-transitory computer-readable media include, for example, magnetic storage devices (eg, hard disks, floppy disks, magnetic strips), optical disks (eg, compact discs (CDs) or digital versatile discs (DVDs)), smart cards, flash memory. devices (such as "flash drives", cards, sticks, or key drives), RAM, ROM, programmable read-only memory (PROM), erasable PROM (EPROM), including EEPROM, registers, removable disks, and computers It includes any other suitable medium for storing software and/or instructions that can be accessed and read. Computer readable media and/or storage 2706 may also include, by way of example, carrier waves, transmission lines, and any other suitable medium for transmitting computer-readable software and/or instructions to be accessed by the computer. The computer readable medium and/or storage 2706 may reside within the processing circuitry 2702, within the processor 2704, external to the processing circuitry 2702, or within the processing circuitry 2702. It may be distributed over multiple entities, including 702. A computer readable medium and/or storage 2706 may be embodied in a computer program product. By way of example, a computer program product may include a computer readable medium in packaging. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure, depending on the particular application and overall design constraints imposed on the overall system. would do.

[0109] The storage 2706 may hold and/or organize software in loadable code segments, modules, applications, programs, etc., which may be referred to herein as software modules 2716. Software modules 2716 may each contain instructions or data that, when installed or loaded on processing circuitry 2702 and executed by one or more processors 2704 , contribute to runtime image 2714 that controls the operation of one or more processors 2704 . The specific instructions, when executed, may cause processing circuitry 2702 to perform functions in accordance with certain methods, algorithms, and processes described herein.

[0110] Some of the software modules 2716 are loaded during initialization of the processing circuitry 2702, and these software modules 2716 operate the processing circuitry 2702 to enable execution of the various functions disclosed herein. can be constructed. For example, some software modules 2716 configure the internal devices and/or logic circuits 2722 of the processor 2704 and provide access to external devices such as the transceiver 2712, bus interface 2708, user interface 2718, timers, math coprocessors, and the like. can be managed. Software modules 2716 may include control programs and/or an operating system that interact with interrupt handlers, device drivers, and control access to various resources provided by processing circuitry 2702 . These resources may include memory, processing time, access to transceiver 2712, user interface 2718, and the like.

[0111] One or more processors 2704 of the processing circuitry 2702 may be multifunctional, whereby some of the software modules 2716 are loaded and configured to perform different functions or different instances of the same function. The one or more processors 2704 may be further adapted to manage background tasks initiated in response to input from, for example, the user interface 2718, transceiver 2712, and device drivers. In order to support execution of multiple functions, one or more processors 2704 may be configured to provide a multitasking environment whereby each of the multiple functions may be executed by one or more processors as needed or desired. It is implemented as a set of tasks serviced by processor 2704 . In one example, a multi-tasking environment can be implemented using a time-sharing program 2720 that passes control of the processor 2704 between different tasks, such that each task receives and/or Control of the one or more processors 2704 is returned to the timesharing program 2720 in response to an input such as an interrupt. When a task controls one or more processors 2704, the processing circuitry is effectively specialized for the purposes addressed by the functions associated with the control task. The time-sharing program 2720 functions as an operating system, a main loop that transfers control on a round-robin basis, functions that assign control of one or more processors 2704 according to function priority, and/or processes control of one or more processors 2704. may include an interrupt-driven main loop that responds to external events by providing

[0112] In one embodiment, the device 2700 includes or includes a wireless charging device having a battery charging power supply coupled to a charging circuit, a plurality of charging cells, and a controller that may be included in one or more processors 2704. works like A plurality of charge cells can be configured to provide a charge surface. One or more coils can be configured to direct an electromagnetic field through the charge transfer region of each charge cell. The controller causes the charging circuit to supply charging current to the resonant circuit when the powered device is placed on the charging surface, detects the change or rate of change in the voltage or current level associated with the resonant circuit, and terminates the charging current for a period of time. It can be configured to determine if the powered device has been removed from the charging surface by providing a measurement slot by allowing the device to operate and performing a passive or digital ping procedure during the measurement slot.

[0113] In one example, the controller can be further configured to initiate a passive ping procedure to determine if the powered device has been removed from the charging surface. A passive ping procedure can be performed between the measurement slots and after terminating the charging current.

[0114] In one example, the controller may be further configured to perform a digital ping procedure to determine if the receiving device has been removed from the charging surface. A digital ping procedure can be performed between the measurement slots and after terminating the charging current.

[0115] In some implementations, the apparatus 2700 includes:<u style="Single">Near the exterior of the charging device</u>has one or more sensors placed in the The controller may further be configured to receive measurements from one or more sensors and measure a voltage or current level associated with the resonant circuit when one of the measurements indicates physical removal of the powered device. The sensors may include strain-measuring sensors, accelerometers, infrared or ultrasonic sensing elements, and/or Hall effect devices.

[0116] In some implementations, the storage 2706 holds instructions and information, which the one or more processors 2704 generate a charging current in the resonant circuit when the powered device is placed on the charging surface of the charging apparatus. , identify changes in voltage or current levels associated with the resonant circuit that may indicate removal from the charging surface of the powered device, and provide a measurement slot by reducing or terminating the charging current for a period of time. , is configured to determine whether the powered device has been removed from the charging surface based on the measurement of the characteristic of the resonant circuit in the measurement slot. In one example, the change in voltage or current level comprises a step change in voltage or current level. A low pass filter may be used to filter short duration or low amplitude step changes in signals representing voltage or current levels.

[0117] In certain implementations, the resonant circuit includes a transmission coil on the charging surface. Characteristics of the resonant circuit may indicate coupling between the transmit coil and the receive coil within the power receiving device. The instructions can be configured to cause the one or more processors 2704 to determine that the powered device has been removed from the charging surface when the voltage measured at the terminals of the transmission coil exceeds a threshold voltage level. In some examples, the threshold voltage level may be maintained by a lookup table. In some examples, a threshold voltage level may be identified when the transmission coil is electromagnetically decoupled. In some examples, the threshold voltage level may be specified when the powered device is first placed on the charging surface.

[0118] In certain implementations, the instructions cause the one or more processors 2704 to determine that the powered device has been removed from the charging surface when the magnitude of the current measured in the resonant circuit is less than a threshold current level. can be configured as In some examples, the threshold current level is maintained by a lookup table. In one example, the threshold current level can be determined when no object is electromagnetically coupled with the coil in the resonant circuit. In another example, the threshold current level can be determined when the powered device is first placed on the charging surface.

[0119] In some implementations, the instructions may be configured to cause the one or more processors 2704 to determine that the powered device has been removed from the charging surface based on the decay rate of the energy stored in the resonant circuit. . In some implementations, the instructions may be configured for one or more processors 2704 to use a passive ping procedure to determine whether the powered device has been removed from the charging surface. A passive ping procedure can be performed during the measurement slot and after the charging current is terminated. In some implementations, the instructions may be configured for one or more processors 2704 to use a digital ping procedure to determine whether the powered device has been removed from the charging surface. A digital ping procedure can be performed during the measurement slot and after termination of the charging current.

[0120] In certain implementations, the instructions may be configured to cause one or more processors 2704 to monitor and/or receive measurements from one or more sensors within the charging surface. The instructions may be configured to cause one or more processors 2704 to measure voltage or current levels associated with the resonant circuit after one of the measurements indicates physical removal of the powered device. The sensors may include strain-measuring sensors, accelerometers, infrared or ultrasonic sensing elements, and/or Hall effect devices.

[0121] FIG. 28 is a flowchart 2800 illustrating a method of operation of a charging surface in accordance with certain aspects of the present disclosure. The method may be performed by a controller within the charging surface. At block 2802, the controller may provide charging current to the resonant circuit when the powered device is placed on the charging surface. At block 2804, the controller detects changes or rates of change in voltage or current levels associated with the resonant circuit. At block 2806, the controller may provide a measurement slot by terminating the charging current for a period of time. At block 2808, the controller determines that the powered device has been removed from the charging surface by performing a passive or digital ping during the measurement slot. If at block 2810 the controller determines that the powered device has been removed from the charging surface, at block 2812 the controller may terminate the charging current and charging cycle associated with the powered device. If at block 2810 the controller determines that the powered device has not been removed from the charging surface, then at block 2804 the method may continue or resume.

[0122] In certain implementations, the controller may perform a passive ping procedure to determine whether the powered device has been removed from the charging surface. This passive ping procedure can be done between measurement slots and after stopping the charging current.

[0123] In certain implementations, the controller may perform a digital ping procedure to determine whether the powered device has been removed from the charging surface. This digital ping procedure can be done between the measurement slots and after terminating the charging current.

[0124] In certain implementations, the controller receives measurements from one or more sensors in the charging surface, and after one of the measurements indicates physical removal of the powered device, the voltage associated with the resonant circuit or Current levels may be measured. The sensors may include strain-measuring sensors, accelerometers, infrared or ultrasonic sensing elements, and/or Hall effect devices.

[0125] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Accordingly, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims, including the singular elements. References to are not intended to mean "only one," but rather "one or more," unless otherwise specified. Unless otherwise specified, the term "a portion" means one or more. All structural and functional equivalents corresponding to the elements of the various aspects described throughout this disclosure that are known, or later become known, to those skilled in the art are expressly incorporated herein by reference. It is intended to be incorporated and covered by the claims. Moreover, nothing disclosed herein is intended to be released to the public, regardless of whether such disclosure is explicitly recited in the claims. An element of a claim is referred to in 35 U.SC § unless the element is explicitly recited with the phrase "means" or, in the case of a method claim, the element is described with the phrase "step." 112 should not be construed on the basis of the provisions of paragraph 6.