Dynamic Multi-Coil Tuning

Abstract

To provide a system, method and apparatus for wireless charging.SOLUTION: A wireless charging device includes a plurality of charging cells disposed on a first surface and a processor configured to provide a charging current to a first charging coil in a surface of the wireless charging device, determine that an impedance of a resonant circuit has varied, and restore a threshold or set point impedance by modifying a frequency of the charging current. The resonant circuit includes the first charging coil. A method of operating the wireless charging device includes the steps of: providing a charging current to the first charging coil on the surface of the wireless charging device, determining that the impedance of the resonant circuit including the charging coil has varied from the threshold or set point impedance; and restoring the threshold or set point impedance by modifying the frequency of the charging current.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] Priority claim This application claims priority to and the benefit of U.S. Patent Application No. 17 / 140,948, filed in the U.S. Patent Office on January 4, 2021, and U.S. Provisional Patent Application No. 62 / 957,420, filed in the U.S. Patent Office on January 6, 2020, the entire contents of which are incorporated herein by reference as if fully set forth below for all applicable purposes.

[0002] Technical Field The present invention relates generally to wireless charging of batteries and includes the use of a multi-coil wireless charging device to charge a battery in a mobile device regardless of the position of the mobile device on the surface of the multi-coil wireless charging device. [Background technology]

[0003] Wireless charging systems have been developed to allow certain types of devices to charge their internal batteries without using a physical charging connection. Devices that can utilize wireless charging include mobile processing and / or communications devices. Standards such as the Qi standard defined by the Wireless Power Consortium allow a device manufactured by one supplier to be wirelessly charged using a charger manufactured by a second supplier. Wireless charging standards are optimized for relatively simple devices and tend to provide basic charging functionality.

[0004] Improvements in wireless charging capabilities are necessary to accommodate the ever-increasing complexity of mobile devices and changing form factors. For example, improved charging techniques are needed for multi-coil, multi-device charging pads. [Brief explanation of the drawings]

[0005] [Figure 1]FIG. 1 illustrates an example of a charging cell that may be used to provide a charging surface according to certain embodiments disclosed herein. [Figure 2] FIG. 2 illustrates an example of an arrangement of charge cells provided on a single layer of a charging surface segment configured according to certain embodiments disclosed herein. [Figure 3] FIG. 3 illustrates an example of a charge cell arrangement when multiple layers are stacked within a segment of a charging surface configured according to certain embodiments disclosed herein. [Figure 4] FIG. 4 illustrates the layout of power transfer areas provided by a charging surface using multiple layers of charging cells constructed in accordance with certain embodiments disclosed herein. [Figure 5] FIG. 5 illustrates a wireless transmitter that may be provided in a charger base station according to certain aspects disclosed herein. [Figure 6] FIG. 6 illustrates a first topology supporting matrix multiplexed switching for use in a wireless charging device adapted in accordance with certain aspects disclosed herein. [Figure 7] FIG. 7 illustrates a second topology for supporting DC drive in a wireless charging device adapted in accordance with certain aspects disclosed herein. [Figure 8] FIG. 8 illustrates a wireless transmitter provided in accordance with certain aspects disclosed herein. [Figure 9] FIG. 9 illustrates a first example of an impedance characteristic of a resonant circuit that may be adapted in accordance with certain embodiments disclosed herein. [Figure 10] FIG. 10 illustrates a continuously tunable wireless transmitter provided in accordance with certain aspects disclosed herein. [Figure 11] FIG. 11 illustrates a second example of an impedance characteristic of a resonant circuit that may be adapted in accordance with certain embodiments disclosed herein. [Figure 12] FIG. 12 illustrates an example of a control circuit that can be adapted in accordance with certain aspects disclosed herein. [Figure 13]FIG. 13 is a flowchart illustrating an example of an object detection method performed by a controller in a wireless charging device adapted in accordance with certain aspects disclosed herein. [Figure 14] FIG. 14 illustrates an example of an apparatus that employs processing circuitry that may be adapted in accordance with certain aspects disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0006] The detailed description set forth below in connection with the accompanying drawings is intended to illustrate various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that the concepts may be practiced without the specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

[0007] Certain aspects of wireless charging systems will now be presented 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 may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0008] For example, an element, any portion of an element, or any combination of elements may be implemented in a “processing system” including 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 other suitable hardware configured to perform various functions described throughout this disclosure. The one or more processors of a processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or the like. Software may reside in a processor-readable storage medium. Processor-readable storage media, also referred to herein as computer-readable media, may include, for example, magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips), optical disks (e.g., compact disks (CDs), digital versatile disks (DVDs)), smart cards, flash memory devices (e.g., cards, sticks, key drives), near field communication (NFC) 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, or any other medium suitable for storing or transmitting software. The computer-readable medium may be resident within a processing system, external to the processing system, or distributed across multiple entities, including the processing system. The computer-readable medium may also be embodied in a computer program product.As an example, a computer program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

[0009] overview Certain aspects of the present disclosure relate to systems, devices, and methods applicable to wireless charging devices that have multiple transmission coils or that provide a freely positionable charging surface capable of simultaneously charging multiple powered devices. In one aspect, a controller of the wireless charging device can determine the location of a device to be charged and configure one or more transmission coils optimally positioned to provide power to the powered device. A charging cell can include or configure one or more inductive power transmitting coils, and multiple charging cells can be positioned or configured to provide a charging surface. The location of the device to be charged can be detected via sensing techniques that relate the device's location to changes in physical properties about a known location on the charging surface. In some examples, position sensing can be implemented using capacitive, resistive, inductive, contact, pressure, load, strain, and / or another suitable type of sensing.

[0010] Certain aspects disclosed herein relate to improved wireless charging technology. Systems, devices, and methods are disclosed that allow flexible placement of rechargeable devices on the surface of a multi-coil wireless charging device. Certain aspects can improve the efficiency and capacity of wireless power transfer to a power receiving device. In one example, the wireless charging device includes a battery charging power source, a plurality of charging cells arranged in a matrix, a first plurality of switches, each configured to couple a row of coils in the matrix to a first terminal of the battery charging power source, and a second plurality of switches, each configured to couple a column of coils in the matrix to a second terminal of the battery charging power source. Each charging cell of the plurality of charging cells may include one or more coils surrounding a power transfer area. The plurality of charging cells may be positioned adjacent to the charging surface without overlapping power transfer areas of the charging cells of the plurality of charging cells.

[0011] In one aspect of the disclosure, the device includes a battery charging power source and a plurality of charge cells, and the controller can select and couple each charge cell to the power source as needed or desired. Each charge cell of the plurality of charge cells can include one or more coils surrounding a power transfer area. The plurality of charge cells can be positioned adjacent to a charging surface without the power transfer areas of the charge cells overlapping.

[0012] Certain aspects of the present disclosure relate to wireless charging systems, devices, and methods that use stacked coils that can charge a target device placed on a charging device without requiring it to conform to a specific geometric shape or location within the charging surface of the charging device. Each coil can have a substantially polygonal shape. In one example, each coil can have a hexagonal shape. Each coil can be implemented using spiraled wire, printed circuit board traces, and / or other connectors. Each coil can span two or more layers separated by an insulator or substrate such that the coils on different layers are centered about a common axis.

[0013] According to certain aspects disclosed herein, power can be wirelessly transmitted to a powered device located anywhere on a charging surface, which can have any defined size and / or shape, regardless of any individual location where charging is enabled. Multiple devices can be charged simultaneously on a single charging surface. Charging surfaces can be manufactured using printed circuit board technology in low-cost and / or compact designs.

[0014] Charging cell Certain aspects of the present disclosure relate to systems, devices, and methods applicable to wireless charging devices that have multiple transmitting coils or provide a freely positionable charging surface capable of simultaneously charging multiple powered devices. In one aspect, a processing circuit coupled to the freely positionable charging surface is configured to identify the location of the device to be charged and can select and configure one or more transmitting coils optimally positioned to provide power to the powered device. The charging cells can be configured with one or more inductive transmitting coils, and the multiple charging cells can be arranged or configured to provide a charging surface. The location of the device to be charged can be detected by a sensing technique that associates the device's location with a change in a physical property centered on a known location on the charging surface. In some examples, position sensing can be implemented using capacitive, resistive, inductive, contact, pressure, load, strain, and / or another suitable type of sensing.

[0015] According to certain aspects disclosed herein, a charging surface can be provided using charging cells deployed adjacent to the charging surface. In one example, the charging cells are arranged according to a honeycomb packaging configuration. The charging cells can be implemented with one or more coils, each capable of inducing a magnetic field along an axis substantially perpendicular to the charging surface adjacent the coil. As used herein, a charging cell refers to an element having one or more coils, each configured to generate an electromagnetic field that is additive to the electromagnetic fields generated by other coils in the charging cell and directed along or adjacent a common axis. As used herein, the coils of a charging cell are referred to as charging coils or transmitting coils.

[0016] In some implementations, a charging cell includes coils stacked along a common axis. One or more coils may be stacked to contribute to an induced magnetic field substantially perpendicular to the charging surface. In some examples, a charging cell includes a coil disposed within a defined portion of the charging surface that contributes to an induced magnetic field within the defined portion of the charging surface, which contributes to a magnetic flux flowing generally perpendicular to the charging surface. In some embodiments, the charging cell may be dynamically configurable by providing an activation current to the coils included in the defined charging cell. For example, a wireless charging device may include multiple stacks of coils deployed across a charging surface, and the wireless charging device may detect the location of a device to be charged and select some combination of the stacks of coils to provide a charging cell adjacent to the device to be charged. In some embodiments, a charging cell may include or be characterized as a single coil. However, it should be understood that a charging cell may include multiple stacked coils and / or multiple adjacent coils or stacks of coils.

[0017] FIG. 1 illustrates an example of a charging cell 100 that may be deployed or configured to provide a charging surface for a wirelessly powered device. In this example, the charging cell 100 has a substantially hexagonal shape surrounding one or more coils 102 constructed using conductors, wires, or circuit board traces capable of receiving sufficient current to generate an electromagnetic field in a power transfer region 104. In various embodiments, some coils 102 may have a substantially polygonal shape, including the hexagonal charging cell 100 shown in FIG. 1 . Other embodiments may include or have coils 102 with other shapes. The shape of the coils 102 may be determined, at least in part, by the capabilities or limitations of manufacturing technology or to optimize the layout of the charging cell on a substrate 106, such as a printed circuit board. Each coil 102 may be spirally implemented using wires, printed circuit board traces, and / or other connectors. Each charging cell 100 may span two or more layers separated by insulators or the substrate 106, such that the coils 102 of the various layers are arranged about a common axis 108.

[0018] FIG. 2 illustrates an example arrangement 200 of charge cells 202 provided on a single layer of a segment or portion of a charging surface configured according to certain embodiments disclosed herein. The charge cells 202 are arranged according to a honeycomb packaging configuration. In this example, the charge cells 202 are arranged end-to-end with no overlap. This arrangement can be provided without through-holes or wire interconnects. Other arrangements are possible, including arrangements in which some of the charge cells 202 overlap. For example, the wires of two or more coils may be interleaved to some extent.

[0019] FIG. 3 illustrates an example of charge cell placement from two perspectives 300, 310, where multiple layers overlap within a segment or portion of a charging surface configured according to certain embodiments disclosed herein. Layers 302, 304, 306, and 308 of charge cells are provided within the charging surface. The charge cells within each layer 302, 304, 306, and 308 of charge cells are arranged according to a honeycomb packaging configuration. In one example, each layer 302, 304, 306, and 308 of charge cells may be formed on a printed circuit board having four or more layers. The placement of the charge cells 100 can be selected to completely cover a designated charging area adjacent to the illustrated segment.

[0020] 4 illustrates the arrangement of power transfer areas provided on a charging surface 400 employing multiple layers of charge cells configured in accordance with certain embodiments disclosed herein. The illustrated charging surface is comprised of four layers of charge cells 402, 404, 406, and 408. In FIG. 4, each power transfer area provided by a charge cell in the first layer of charge cells 402 is labeled "L1," each power transfer area provided by a charge cell in the second layer of charge cells 404 is labeled "L2," each power transfer area provided by a charge cell in the third layer of charge cells 406 is labeled "L3," and each power transfer area provided by a charge cell in the fourth layer of charge cells 408 is labeled "L4."

[0021] wireless transmitter FIG. 5 illustrates an example of a wireless transmitter 500 that may be provided in a base station of a wireless charging device. The base station in the wireless charging device may include one or more processing circuits used to control the operation of the wireless charging device. A controller 502 may receive a feedback signal filtered or otherwise processed by a filter circuit 508. The controller may control the operation of a driver circuit 504 that supplies an AC current to a resonant circuit 506. In some examples, the controller 502 may generate a digital frequency reference signal used to control the frequency of the AC current output by the driver circuit 504. In some implementations, the digital frequency reference signal may be generated using a programmable counter or the like. In some examples, the driver circuit 504 includes a power inverter circuit and one or more power amplifiers that cooperate to generate an AC current from a DC source or input. In some examples, the digital frequency reference signal may be generated by the driver circuit 504 or another circuit. The resonant circuit 506 includes a capacitor 512 and an inductor 514. The inductor 514 may represent or include one or more transmission coils in a charging cell that generate magnetic flux in response to an AC current. 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.

[0022] A passive ping technique can use the voltage and / or current measured or observed at the LC node 510 to identify the presence of a receiving coil in proximity to a charging pad of a device adapted according to certain aspects disclosed herein. Some conventional wireless charging devices include circuitry that measures the voltage at the LC node 510 of the resonant circuit 506 or the current in the resonant circuit 506. These voltages and currents can be monitored for power regulation purposes and / or to support communication between devices. According to certain aspects of the present disclosure, the voltage at the LC node 510 of the wireless transmitter 500 shown in FIG. 5 can be monitored to support a passive ping technique to detect the presence of a rechargeable device or other object based on the resonant circuit 506's response to a short energy burst (ping) transmitted through the resonant circuit 506.

[0023] Passive ping sensing techniques can be used to provide fast and low-power sensing. A passive ping can be generated by driving a network including a resonant circuit 506 with a fast pulse containing a small amount of energy. The fast pulse excites the resonant circuit 506, causing the network to oscillate at its natural resonant frequency until the injected energy decays and dissipates. The response of the resonant circuit 506 to the fast pulse can be determined in part by the resonant frequency of the resonant LC circuit. The response of the resonant circuit 506 to a passive ping with an initial voltage = V is determined by the voltage V observed at the LC node 510. LC It can be expressed as follows: TIFF0007776897000001.tif11170

[0024] The resonant circuit 506 can be monitored by the controller 502 or another processor to detect the presence of an object using a digital ping. The digital ping is generated by driving the resonant circuit 506 for a period of time. The resonant circuit 506 is a tuned network that includes the wireless charging device's transmit coil. The powered device can modulate the voltage or current observed across the resonant circuit 506 by changing the impedance presented by its powered circuit according to the signaling state of the modulation signal. The controller 502 or other processor then waits for a data modulation response indicating that the powered device is nearby.

[0025] Selective coil activation According to certain aspects disclosed herein, coils in one or more charging cells can be selectively activated to provide an optimal electromagnetic field for charging a compatible device. In some examples, coils are assigned to charging cells, and some charging cells may overlap with other charging cells. An optimal charging configuration can be selected at the charge cell level. In some examples, the charging configuration can include charging cells in a charging surface determined to be aligned with or located near a device to be charged. The controller can activate a single coil or a combination of coils based on the charging configuration based on detecting the location of the device to be charged. In some embodiments, the wireless charging device may have driver circuitry capable of selectively activating one or more transmitting coils or one or more predefined charging cells during a charging event.

[0026] FIG. 6 illustrates a first topology 600 supporting matrix multiplexing switching for use in a wireless charging apparatus adapted according to certain embodiments disclosed herein. The wireless charging apparatus can select one or more charge cells 100 to charge a powered device. Unused charge cells 100 can be disconnected from the current flow. A relatively large number of charge cells 100 can be used in the honeycomb packaging configuration shown in FIGS. 2 and 3 , which may require a corresponding number of switches. According to certain embodiments disclosed herein, the charge cells 100 can be logically arranged in a matrix 608 with multiple cells connected to two or more switches that enable power to be supplied to a particular cell. In the illustrated topology 600, a two-dimensional matrix 608 is provided, whose dimensions can be represented by X and Y coordinates. Each of a first set of switches 606 is configured to selectively couple a first terminal of each cell in the string to a first terminal of a voltage or current source 602 that provides current to operate coils in one or more charge cells during wireless charging. Each of the second set of switches 604 is configured to selectively couple the second terminal of each cell in the row of cells to the second terminal of the voltage or current source 602. A charging cell is active when both terminals of the cell are coupled to the voltage or current source 602.

[0027] The use of matrix 608 can significantly reduce the number of switching 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 608 having N cells can be operated with √N switches. The use of matrix 608 can significantly reduce cost and circuit and / or layout complexity. In one example, a nine-cell implementation can be implemented in a 3×3 matrix 608 using six switches, saving three switches. In another example, a 16-cell implementation can be implemented in a 4×4 matrix 608 using eight switches, saving eight switches.

[0028] During operation, at least two switches are closed to actively couple one coil or charge cell to the voltage or current source 602. Multiple switches can be closed at once to facilitate connecting multiple coils or charge cells to the voltage or current source 602. Multiple switches can be closed to enable an operating mode that drives multiple transmit coils, for example, when transferring power to a powered device.

[0029] FIG. 7 illustrates a second topology 700 in which each individual coil or charge cell is directly driven by a driver circuit 702, according to certain aspects disclosed herein. The driver circuit 702 can be configured to select one or more coils or charge cells 100 from a group of coils 704 to charge a powered device. It will be understood that the concepts disclosed herein with respect to charge cells 100 can be applied to selective activation of individual coils or stacks of coils. No current flows through unused charge cells 100. A relatively large number of charge cells 100 can be used, and a switching matrix can be used to drive the individual coils or groups of coils. In one example, a first switching matrix can configure connections defining the charge cells or groups of coils to be used during a charging event, and a second switching matrix can be used to activate the charge cells and / or selected groups of coils.

[0030] Dynamic Multi-Coil Tuning Certain aspects disclosed herein relate to a tuning network including one or more capacitors and one or more inductors. The tuning network may be used in a charging system in which a base station is electromagnetically coupled to a powered device. The network may be tuned to optimize power transfer, enable communication between the base station and the powered device, or enable the base station to detect the presence of a powered device. Some wireless charging devices and power supplies are designed to maintain a constant set point, which defines a power, current, or voltage level.

[0031] Certain aspects of the present disclosure provide techniques usable in wireless charging devices to maintain or sustain the performance of circuits that use tuned circuits. FIG. 8 illustrates a wireless transmission circuit 800 in a wireless charging device base station that can couple a driver 804 to one or more coils 812 a, 812 b, and 812 c in a resonant circuit 806 during charging and / or detection operations. In one example, each coil 812 a, 812 b, and 812 c corresponds to a transmission coil activated by a charging configuration. In another example, each coil 812 a, 812 b, and 812 c represents one charge cell selected to transmit power by the charging configuration. While the illustrated example shows three coils 812 a, 812 b, and 812 c, it should be understood that more coils may be selected or affected by the charging configuration. The coils 812 a, 812 b, and 812 c coupled to the driver 804 may be selected to provide an optimized charging configuration that facilitates power delivery to the location of a powered device placed on a charging surface. In the illustrated example, the resonant circuit 806 is formed by a set of switches 814a, 814b, 814c that allow each coil 812a, 812b, 812c to be selectively coupled to a charging current source 810 provided by the driver 804 via a capacitor 808. The impedance of the resonant circuit 806 is determined by a nominal capacitance (C res) and the combination of coupled coils 812a, 812b, and 812c. In the illustrated example, each of the coils 812a, 812b, and 812c has a nominal inductance (L res ) The impedance of the resonant circuit 806 varies with the number of coils 812a, 812b, 812c coupled to the driver 804. Thus, a resonant circuit 806 that is tuned when it includes a capacitor 808 and one or more coils 812a, 812b, 812c becomes detuned when the number of coils 812a, 812b, 812c is changed.

[0032] In certain aspects of the present disclosure, table-based dynamic tuning may be used when the configuration of the resonant circuit 806 is changed. The resonant frequency of a tuned resonant circuit 806 may change when additional inductors are switched into the resonant circuit 806. The power transfer level or efficiency of the wireless transmission circuit 800 may be optimized when the frequency of the charging current 810 is adjusted to match the resonant frequency of the resonant circuit 806, and may be maintained optimized by readjusting the frequency of the charging current 810 after the frequency of the resonant circuit 806 is changed. A set point associated with the wireless transmission circuit 800 may be maintained by adjusting the frequency of the charging current 810 to obtain a desired or specified level of power, current, and / or voltage.

[0033] The frequency of the charging current 810 may be referred to herein as an operating point. The operating point may be selected via a lookup table that associates frequencies with the number, type, and / or identity of coils included in the resonant circuit 806. In one example, the lookup table may associate frequencies with known values ​​of inductance associated with the individual coils included in the resonant circuit 806. The lookup table may be used to maintain a substantially constant output from the power source from the wireless transmission circuit 800. For example, the lookup table may provide information that allows the controller 802 or another processor to change the frequency of the charging current 810 provided by the driver 804 in conjunction with changes in the coil configuration.

[0034] Graph 900 in FIG. 9 shows impedance characteristics 902, 904 for two configurations of resonant circuit 806, which include different numbers of coils 812a, 812b, and 812c. The resonant circuit 806 can be designed using a set point obtained when the resonant circuit 806 has a nominal or optimal impedance 910. The impedance characteristics 902, 904 indicate that the impedance is a function of the frequency of the charging current 810 and varies with the resonant frequency. As the configuration of the resonant circuit 806 changes, the controller 802 can modify the frequency of the charging current 810 to obtain the nominal or optimal impedance 910. In implementations where the number of resonant circuit 806 configurations is finite or limited, a lookup table can be used to define the frequency of the charging current 810 for each configuration of the resonant circuit 806. The frequencies recorded in the table can be obtained during initial configuration during device assembly or manufacturing and / or can be updated or calibrated during operation of the wireless transmission circuit 800. A lookup table based approach may be used to allow fast and low overhead tuning between operating points 906, 908.

[0035] According to certain aspects of the present disclosure, the resonant circuit 806 may be continuously tuned in some implementations. FIG. 10 illustrates a continuously tunable wireless transmitter 1000 provided at a wireless charging device base station, and a graph 1100 in FIG. 11 illustrates impedance characteristics 1102, 1104 corresponding to two different configurations of the resonant circuit 806 and / or the configuration of the resonant circuit 806 as affected by different positions of the powered device coupled to the resonant circuit 806. As shown in FIG. 11 , the resonant circuit 806 transitions 1110 from a first operating point 1106 to a second operating point 1108. The transition between the operating points 1106, 1108 may be caused by a change in the number of activated coils 812 a, 812 b, 812 c in the resonant circuit 806 and / or a repositioning of the powered device, which affects the electromagnetic coupling between the resonant circuit 806 and the powered device.

[0036] The continuously tunable wireless transmitter 1000 includes elements of the wireless transmission circuit 800 of FIG. 8 plus an additional feedback loop 1002. In one example, the feedback loop 1002 operates as a current-sensing feedback loop that allows the driver 804 or controller 802 to monitor the power transfer indicated by the current flowing through the resonant circuit 806. The driver 804 or or controller 802 can adjust the operating point 1106, 1108 to track changes in the impedance of the resonant circuit 806. In one example, changes in the impedance of the resonant circuit 806 are tracked by incrementally adjusting the frequency of the charging current 810.

[0037] The driver 804 or controller 802 may include or implement proportional-integral-derivative (PID) tuning. The PID tuning may be performed using a control loop that includes a current sense feedback 1002. The driver 804 or controller 802 may continuously calculate an error value as the difference between a desired set point for current flow in the resonant circuit 806 and the measured current flow in the resonant circuit 806 as indicated by the current sense feedback 1002. The driver 804 or controller 802 may apply a correction calculated as some combination of proportional, integral, and derivative values ​​(referred to as a P value, an I value, and a D value, respectively).

[0038] PID-based dynamic tuning can be implemented as a PID loop that is enabled after and / or during a change in the configuration of the resonant circuit 806. A sufficiently fast PID loop can free-run and apply changes without additional delay. In some cases, the PID loop implemented by the driver 804 or controller 802 may not respond quickly enough to changes in the configuration of the resonant circuit 806, and a transition period can be added to gradually change the configuration from one operating point to another. In one example, a delay may be introduced using pulse width modulation applied to the switches 814a, 814b, and 814c, or via the switches 814a, 814b, and 814c transitioning in a linear operating mode.

[0039] FIG. 12 shows an example of a PID control circuit 1200. A defined set point 1202 and current sense feedback 1204 are received and combined to obtain an error value 1206, which is provided to a PID processor 1208. The PID processor 1208 generates a control signal 1210 that controls a frequency generator 1212 used to provide the charging current 810. A timing diagram 1220 illustrates the gradual transition in frequency of the charging current 810 when the driver 804 or controller 802 cannot respond quickly enough to changes in the configuration of the resonant circuit 806. It will be understood that other control circuits and / or algorithms may be used, including, for example, systems using controllers based on Prandtl-Ishlinskii (PI) hysteresis, etc. The type of control loop used is selected based on system requirements or specifications.

[0040] FIG. 13 is a flowchart 1300 illustrating an example method of operating a wireless charging device. The method may be performed by a controller included in the wireless charging device. In block 1302, the controller may provide a charging current to a first charging coil on a surface of the wireless charging device. In block 1304, the controller may determine that the impedance of a resonant circuit has changed from a threshold or set point impedance. The resonant circuit may include the first charging coil. In block 1306, the controller may restore the threshold or set point impedance by changing the frequency of the charging current.

[0041] In certain implementations, the controller can couple a second charging coil to the resonant circuit. The controller can provide a charging current to the second charging coil. The coupling of the second charging coil can change the impedance of the resonant circuit. The controller can use a lookup table to determine a frequency of the charging current to be used after the second charging coil is coupled to the resonant circuit.

[0042] In some embodiments, the controller can decouple the second charging coil from the resonant circuit. Decoupling the second charging coil can change the impedance of the resonant circuit. The controller can use a lookup table to determine the frequency of the charging current to be used after the second charging coil is decoupled from the resonant circuit.

[0043] In one example, the impedance of the resonant circuit is changed by changing the position of the power receiving device on the surface of the wireless charging apparatus.

[0044] In certain embodiments, the controller can detect a change in a monitor current flowing through the resonant circuit and determine that the impedance of the resonant circuit has changed based on the change in the monitor current. The controller can receive a feedback signal representative of the change in the monitor current and control the frequency of the charging current using the feedback signal. Controlling the frequency of the charging current can include adjusting the frequency of the charging current in steps until the impedance of the resonant circuit matches a threshold or setpoint impedance. Controlling the frequency of the charging current can include delaying changes in the frequency of the charging current.

[0045] Processing circuit example FIG. 14 illustrates an example of a hardware implementation of an apparatus 1400 that can be incorporated into a wireless charging apparatus or a powered device that enables wireless charging of a battery. In some examples, the apparatus 1400 can perform one or more functions disclosed herein. According to various aspects of the present disclosure, the elements, any portion of the elements, or any combination of the elements disclosed herein can be implemented using a processing circuit 1402. The processing circuit 1402 can include one or more processors 1404 controlled by a combination of hardware and software modules. Examples of the processor 1404 include a microprocessor, a microcontroller, a digital signal processor (DSP), an SoC, an ASIC, a field programmable gate array (FPGA), a programmable logic device (PLD), a state machine, a sequencer, gate logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout this disclosure. The one or more processors 1404 can include dedicated processors that perform specific functions and can be configured, augmented, or controlled by one of the software modules 1416. The one or more processors 1404 may be configured through a combination of software modules 1416 loaded during initialization and may be further configured by loading or unloading one or more software modules 1416 during operation.

[0046] In the depicted example, the processing circuit 1402 may be implemented with a bus architecture, indicated generally by a bus 1410. The bus 1410 may include any number of interconnected buses and bridges, depending on the particular application and overall design constraints of the processing circuit 1402. The bus 1410 links various circuits, including one or more processors 1404 and storage 1406. The storage 1406 may include memory devices and mass storage devices, and is also referred to herein as a computer-readable medium and / or a processor-readable medium. The storage 1406 may include a transient storage medium and / or a non-transitory storage medium.

[0047] The bus 1410 may link various other circuits, such as timing sources, timers, peripherals, voltage regulators, and power management circuits. A bus interface 1408 may provide an interface between the bus 1410 and one or more transceivers 1412. In one example, the transceiver 1412 may be provided to allow the device 1400 to communicate with a charging device or a powered device according to a standard defined protocol. Depending on the nature of the device 1400, a user interface 1418 (e.g., keypad, display, speaker, microphone, joystick) may also be provided and may be communicatively coupled to the bus 1410 directly or via the bus interface 1408.

[0048] The processor 1404 may be responsible for managing the bus 1410 and for overall processing, including the execution of software stored on computer-readable media, including storage 1406. In this regard, the processing circuitry 1402, including the processor 1404, may be used to implement any of the methods, functions, and techniques disclosed herein. The storage 1406 may be used to store data that is manipulated by the processor 1404 when executing software, which may be configured to perform any one of the methods disclosed herein.

[0049] The one or more processors 1404 of the processing circuitry 1402 can execute software. Software shall be interpreted broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, algorithms, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside in storage 1406 in computer-readable form or on an external computer-readable medium. The external computer-readable medium and / or storage 1406 may include non-transitory computer-readable media. Non-transitory computer-readable media may include, for example, magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips), optical disks (e.g., compact disks (CDs), digital versatile disks (DVDs)), smart cards, flash memory devices (e.g., “flash drives,” cards, sticks, key drives), RAM, ROM, programmable read-only memory (PROM), erasable PROM (EPROM) including EEPROM, registers, removable disks, and any other suitable medium for storing software and / or instructions that can be accessed and read by a computer. Computer-readable media and / or storage 1406 may also include, for example, carrier waves, transmission lines, and any other suitable medium for transmitting software and / or instructions that can be accessed and read by a computer. Computer-readable media and / or storage 1406 may be resident in processing circuit 1402, in processor 1404, external to processing circuit 1402, or distributed across multiple entities, including processing circuit 1402. The computer readable medium and / or storage 1406 may be embodied in a computer program product.As an example, a computer program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

[0050] Storage 1406 may maintain and / or organize software such as loadable code segments, modules, applications, programs, etc., some or all of which are also referred to herein as software modules 1416. Each of the software modules 1416 may include instructions and data that, when installed or loaded into the processing circuitry 1402 and executed by one or more processors 1404, contribute to a runtime image 1414 that controls the operation of the one or more processors 1404. Particular instructions, when executed, may cause the processing circuitry 1402 to perform functions in accordance with particular methods, algorithms, and processes described herein.

[0051] Some of the software modules 1416 may be loaded during initialization of the processing circuit 1402, and these software modules 1416 may configure the processing circuit 1402 to enable it to perform various functions disclosed herein. For example, some software modules 1416 may configure the internal devices and / or logic circuits 1422 of the processor 1404 and may manage access to external devices such as the transceiver 1412, the bus interface 1408, the user interface 1418, timers, and math coprocessors. The software modules 1416 may include a control program and / or operating system that interacts with interrupt handlers and device drivers and controls access to various resources provided by the processing circuit 1402. Resources may include memory, processing time, access to the transceiver 1412, the user interface 1418, and the like.

[0052] The one or more processors 1404 of the processing circuit 1402 are multifunctional, whereby some of the software modules 1416 can be loaded and configured to perform different functions or different instances of the same function. Additionally, the one or more processors 1404 may be adapted to manage background tasks initiated in response to inputs, for example, from the user interface 1418, the transceiver 1412, and device drivers. To support the execution of multiple functions, the one or more processors 1404 may be configured to provide a multitasking environment, whereby each of the multiple functions is implemented as a set of tasks provided by the one or more processors 1404 as needed. In one example, the multitasking environment may be implemented using a time-sharing program 1420 that hands over control of the processor(s) 1404 between different tasks, whereby each task returns control of the one or more processors 1404 to the time-sharing program 1420 upon completion of outstanding operations and / or in response to inputs such as interrupts. When a task has control of the one or more processors 1404, the processing circuit is effectively specialized for the purpose addressed by the function associated with the controlling task. The time-sharing program 1420 may include an operating system, a main loop that transfers control in a round-robin manner, a function that allocates control of one or more processors 1404 according to function priority, and / or an interrupt-operated main loop that responds to external events by providing control of one or more processors 1404 to processing functions.

[0053] In one example, device 1400 includes or operates as a wireless charging device having a battery charging power source coupled to a charging circuit, a plurality of charging cells, and a controller that may be included in one or more processors 1404. The plurality of charging cells may be configured to provide a charging surface. At least one coil may be configured to induce an electromagnetic field through a charge transfer area of ​​each charging cell.

[0054] The controller can be configured to provide a charging current to a first charging coil within a surface of the wireless charging device, determine when an impedance of the resonant circuit has changed from a threshold or set point impedance, and restore the threshold or set point impedance by changing a frequency of the charging current. The resonant circuit can include the first charging coil.

[0055] In a particular example, the controller can couple a second charging coil to the resonant circuit and provide a charging current to the second charging coil. The coupling of the second charging coil can change the impedance of the resonant circuit. The controller can use a lookup table to determine the frequency of the charging current to be used after the second charging coil is coupled to the resonant circuit.

[0056] In a particular example, the controller can decouple the second charging coil from the resonant circuit. Decoupling the second charging coil can change the impedance of the resonant circuit. The controller can use a lookup table to determine the frequency of the charging current to be used after the second charging coil is decoupled from the resonant circuit.

[0057] In one example, the impedance of the resonant circuit is changed by changing the position of the power receiving device on the surface of the wireless charging apparatus.

[0058] In a particular example, the controller can detect a change in a monitor current flowing through the resonant circuit and determine that the impedance of the resonant circuit has changed based on the change in the monitor current. The controller can receive a feedback signal representative of the change in the monitor current and control the frequency of the charging current using the feedback signal. Controlling the frequency of the charging current can include adjusting the frequency of the charging current in steps until the impedance of the resonant circuit matches a threshold or setpoint impedance. Controlling the frequency of the charging current can include delaying changes in the frequency of the charging current.

[0059] In a particular example, the storage 1406 maintains instructions and information configured to cause the controller to provide a charging current to a first charging coil on a surface of the wireless charging device, determine that the impedance of the resonant circuit has varied from a threshold or set point impedance, and restore the threshold or set point impedance by altering the frequency of the charging current. The resonant circuit can include the first charging coil.

[0060] In some examples, the instructions are configured to cause the controller to couple a second charging coil to the resonant circuit and provide a charging current to the second charging coil. The coupling of the second charging coil may change the impedance of the resonant circuit. The instructions may be configured to cause the controller to determine, using a lookup table, a frequency of the charging current to be used after the second charging coil is coupled to the resonant circuit.

[0061] In some examples, the instructions are configured to cause the controller to decouple the second charging coil from the resonant circuit. Decoupling the second charging coil may change the impedance of the resonant circuit. The controller may use a lookup table to determine a frequency of the charging current to be used after the second charging coil is decoupled from the resonant circuit.

[0062] In one example, the impedance of the resonant circuit is changed by changing the position of the power receiving device on the surface of the wireless charging apparatus.

[0063] In some examples, the instructions are configured to cause the controller to detect a change in a monitor current flowing through the resonant circuit and determine that an impedance of the resonant circuit has changed based on the change in the monitor current. The controller can receive a feedback signal representative of the change in the monitor current and control a frequency of the charging current using the feedback signal. Controlling the frequency of the charging current may include adjusting the frequency of the charging current in steps until the impedance of the resonant circuit matches a threshold or setpoint impedance. Controlling the frequency of the charging current may include delaying a change in the frequency of the charging current.

[0064] The foregoing description is provided to enable those skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments. Therefore, the claims are not intended to be limited to the embodiments set forth herein but are to be accorded the full scope consistent with the language of the claims, and references to elements in the singular shall mean "one or more," not "one and only," unless expressly stated otherwise. The term "some" refers to one or more, unless otherwise specified. All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure that are known or later become known to those skilled in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is expressly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. 112, paragraph 6, unless the claim element is expressly recited using the phrase "means for," or, in the case of a method claim, the phrase "step for."

Claims

1. A method for operating a wireless charging device, comprising: supplying a charging current at a first frequency to a resonant circuit, the resonant circuit comprising a first transmission coil of a wireless charging device; connecting a second transmission coil of the wireless charging device to the resonant circuit; determining an impedance of the resonant circuit after connecting the second transmission coil to the resonant coil; after connecting the second transmission coil to the resonant coil, supplying the charging current at a second frequency to the resonant circuit based on an impedance of the resonant circuit; prior to connecting the second transmission coil to the resonant circuit, the first frequency corresponds to a first resonant frequency associated with the resonant circuit; after connecting the second transmission coil to the resonant circuit, the second frequency corresponds to a second resonant frequency associated with the resonant circuit; providing the charging current at the second frequency to restore a nominal impedance of the resonant circuit.

2. The method of claim 1 further comprising:

10. The method of claim 9, further comprising using a lookup table to determine the second frequency.

3. 10. The method of claim 1, wherein a current sensing feedback loop is used to track changes in impedance of the resonant circuit.

4. 10. The method of claim 1, wherein proportional-integral-derivative (PID) tuning is used to track changes in impedance of the resonant circuit.

5. In a non-transitory processor-readable storage medium, code comprising: supplying a charging current at a first frequency to a resonant circuit, the resonant circuit comprising a first transmission coil of a wireless charging device; connecting a second transmission coil of the wireless charging device to the resonant circuit; determining an impedance of the resonant circuit after connecting the second transmission coil to the resonant coil; after connecting the second transmission coil to the resonant coil, supplying the charging current at a second frequency to the resonant circuit based on an impedance of the resonant circuit; prior to connecting the second transmission coil to the resonant circuit, the first frequency corresponds to a first resonant frequency associated with the resonant circuit; after connecting the second transmission coil to the resonant circuit, the second frequency corresponds to a second resonant frequency associated with the resonant circuit; 4. A non-transitory processor-readable storage medium, comprising: providing the charging current at the second frequency to restore a nominal impedance of the resonant circuit.

6. The storage medium according to claim 5 further comprises:

10. A storage medium comprising code for performing the step of using a lookup table to determine the second frequency.

7. 6. The storage medium of claim 5, wherein a current sensing feedback loop is used to track changes in impedance of the resonant circuit.

8. 6. The storage medium of claim 5, wherein proportional-integral-derivative (PID) tuning is used to track changes in impedance of the resonant circuit.

9. In a wireless charging device, a plurality of transmission coils provided on a surface of the wireless charging device; a resonant circuit having a first transmission coil of the plurality of transmission coils; a controller; The controller: providing a charging current at a first frequency to the resonant circuit from a power source; connecting a second transmission coil of the wireless charging device to the resonant circuit; determining an impedance of the resonant circuit after connecting the second transmission coil to the resonant coil; after connecting the second transmission coil to the resonant coil, supplying the charging current at a second frequency from the power source to the resonant circuit based on an impedance of the resonant circuit; prior to connecting the second transmission coil to the resonant circuit, the first frequency corresponds to a first resonant frequency associated with the resonant circuit; after connecting the second transmission coil to the resonant circuit, the second frequency corresponds to a second resonant frequency associated with the resonant circuit; A wireless charging device, characterized in that the nominal impedance of the resonant circuit is restored by supplying the charging current at the second frequency.

10. The wireless charging device according to claim 9, The wireless charging device, wherein the controller is further configured to use a lookup table to determine the second frequency.

11. 10. The wireless charging device of claim 9, wherein a current sensing feedback loop is used to track changes in impedance of the resonant circuit.

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