ACTIVE COOLING IN A MULTI-DEVICE WIRELESS CHARGER

Systems, methods and apparatus for wireless charging are disclosed. A wireless charging device has a plurality of planar power transmitting coils, a driver circuit and at least one substrate having channels formed therein. The channels can receive a flow of air at a port of entry and conduct the flow of air through the substrate to a port of exit. The planar power transmitting coils may be supported by at least one substrate. Each planar power transmitting coil may be formed as a spiral winding surrounding a power transfer area. The driver circuit may be configured to provide a charging current to one or more of the planar power transmitting coils when a chargeable device is placed on or near the wireless charging device. The one or more channels may be configured to conduct the flow of air past or through the planar power transmitting coils and the driver circuit.

TECHNICAL FIELD

The present invention relates generally to wireless charging of batteries, including batteries in mobile computing devices, and more particularly to removal of heat from a charging surface of a wireless charging device.

BACKGROUND

Wireless charging systems have been deployed to enable certain types of devices to charge internal batteries without the use of a physical charging connection. Devices that can take advantage of wireless charging include mobile computing/processing devices and mobile communication devices. Standards, such as the Qi standard defined by the Wireless Power Consortium enable devices manufactured by a first supplier to be wirelessly charged using a charger manufactured by a second supplier. Standards for wireless charging are optimized for relatively simple configurations of devices and tend to provide basic charging capabilities.

Improvements in wireless charging capabilities are required to support continually increasing complexity of mobile devices and changing form factors and to support new uses of wireless charging devices. For example, there is a need for charging devices that provide higher power. There is also a need to control temperature in wireless charging systems, and to remove, dissipate or limit heat generated through losses and other inefficiencies arising from wireless charging systems.

DETAILED DESCRIPTION

By way of example, an element, or 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, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the 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, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a processor-readable storage medium. A processor-readable storage medium, which may also be referred to herein as a computer-readable medium may include, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disk (CD), digital versatile disk (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), Near Field Communications (NFC) token, random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, a removable disk, a carrier wave, a transmission line, and any other suitable medium for storing or transmitting software. The computer-readable medium may be resident in the processing system, external to the processing system, or distributed across multiple entities including the processing system. 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 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.

Overview

Certain aspects of the present disclosure relate to systems, apparatus and methods associated with wireless charging devices that provide a free-positioning charging surface using multiple transmitting coils, including wireless charging devices that can concurrently charge multiple receiving devices. In one aspect, a controller in the wireless charging device can locate a device to be charged and can configure one or more transmitting coils optimally positioned to deliver power to the receiving device. Charging cells may be provisioned or configured with one or more inductive transmitting coils and multiple charging cells may be arranged or configured to provide the charging surface. The location of a device to be charged may be detected through sensing techniques that associate location of the device with changes in a physical characteristic centered at a known location on the charging surface. In some examples, sensing of location may be implemented using capacitive, resistive, inductive, touch, pressure, load, strain, and/or another appropriate type of sensing.

In one aspect of the disclosure, each charging cell in a plurality of charging cells may be constructed using Litz wire to form a planar or substantially flat winding that provides a Litz coil with a central power transfer area. Each charging cell may include or be associated with multiple Litz coils that have coaxial or overlapping power transfer areas. The plurality of charging cells may be arranged adjacent to the charging surface of the charging device without overlap of the charging cells.

In one example, a wireless charging device has at least one substrate with one or more channels formed therein. The one or more channels may be configured to receive a flow of air at a port of entry and to conduct the flow of air through the substrate to a port of exit. The wireless charging device has a plurality of planar power transmitting coils supported by the at least one substrate. Each planar power transmitting coil may be formed as a spiral winding surrounding a power transfer area. The wireless charging device has a driver circuit configured to provide a charging current to one or more of the plurality of planar power transmitting coils when a chargeable device is placed on or near the wireless charging device. The one or more channels may be configured to conduct the flow of air past or through the plurality of planar power transmitting coils and the driver circuit.

Charging Cells

Certain aspects of the present disclosure relate to systems, apparatus and methods applicable to wireless charging devices that provide a free-positioning charging surface that has multiple transmitting coils or that can concurrently charge multiple receiving devices. In one aspect, a controller in the wireless charging device can locate a device to be charged and can configure one or more transmitting coils optimally positioned to deliver power to the receiving device. Charging cells may be provisioned or configured with one or more inductive transmitting coils and multiple charging cells may be arranged or configured to provide the charging surface. The location of a device to be charged may be detected through sensing techniques that associate location of the device to changes in a physical characteristic centered at a known location on the charging surface. In some examples, sensing of location may be implemented using capacitive, resistive.

According to certain aspects disclosed herein, a charging surface in a wireless charging device may be provided using charging cells that are deployed adjacent to a surface of the charging device. In one example the charging cells are deployed in accordance with a honeycomb packaging configuration in one or more layers below or adjacent to the charging surface. A charging cell may be implemented in a wireless charging device using one or more coils that can each induce a magnetic field along an axis that is substantially orthogonal to the charging surface, adjacent to the coil. In this description, a charging cell may refer to an element having one or more coils where each coil is configured to produce an electromagnetic field that is additive with respect to the fields produced by other coils in the charging cell and directed along or proximate to a common axis. In this disclosure, a coil in a charging cell may be referred to as a charging coil, a transmitting coil, a Litz coil or using some combination of these terms.

In some implementations, a charging cell includes coils that are stacked along a common axis and/or that overlap such that they contribute to the magnetic field that is induced substantially orthogonal to the surface of the charging device. In some implementations, a charging cell includes coils that are arranged within a defined portion of the surface of the charging device and that contribute to an induced magnetic field within the defined portion of the charging surface, the magnetic field contributing to a magnetic flux flowing substantially orthogonal to the charging surface.

In some implementations, charging cells may be configurable by providing an activating current to coils that are included in one or more dynamically-defined charging cells. 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 based on proximity to one or more stacks of coils. The charging device may select some combination of the stacks of coils to define or provide a charging cell adjacent to the device to be charged. In some instances, a charging cell may include, or be characterized as a single coil. However, it should be appreciated that a charging cell may include multiple stacked coils and/or multiple adjacent coils or stacks of coils. The coils may be referred to herein as charging coils, wireless charging coils, transmitter coils, transmitting coils, power transmitting coils, power transmitter coils, or the like.

FIG. 1illustrates an example of a charging cell100that may be deployed and/or configured to provide a charging surface of a wireless charging device. In this disclosure, a charging surface may be understood to include an array of charging cells100provided on one or more substrates106of a printed circuit board, or an array of charging coils embedded in a structure formed from one or more substrates106. A circuit comprising one or more integrated circuits (ICs) and/or discrete electronic components may be provided on one or more of the substrates106. The circuit may include drivers and switches used to control currents provided to coils used to transmit power to a receiving device. The circuit may be implemented using a processing circuit that includes one or more processors and/or one or more controllers that can be configured to perform certain functions disclosed herein. In some instances, some or all of the processing circuit may be provided external to the charging device. In some instances, a power supply may be coupled to the charging device.

The charging cell100may be provided in close proximity to an outer surface area of the charging device, upon which one or more devices can be placed for charging. The charging device may include multiple instances of the charging cell100. In one example, the charging cell100has a substantially hexagonal shape that delimits or encloses one or more coils102. Each coil may be constructed using conductors, wires or circuit board traces that can receive a current sufficient to produce an electromagnetic field in a power transfer area104. In various implementations, some coils102can have an overall shape that is substantially polygonal, including the hexagonal charging cell100illustrated inFIG. 1. In some implementations, one or more coils may have a flat spiral shape or a shape that is substantially circular. Other implementations provide coils102that are circular or elliptical in form or that have some other shape. The shape of the coils102may be determined at least in part by the number of windings in each coil, capabilities or limitations of fabrication technology, and/or to optimize layout of the charging cells on a substrate106such as a printed circuit board substrate. Each coil102may be implemented using wires, printed circuit board traces and/or other connectors in a spiral configuration. Each charging cell100may span two or more layers separated by an insulator or substrate106such that coils102in different layers are centered around a common axis108.

FIG. 2illustrates an example of an arrangement200of charging cells202provided on a single layer of a segment or portion of a charging surface that may be included in a charging system that has been adapted in accordance with certain aspects disclosed herein. The charging cells202are arranged according to a honeycomb packaging configuration. In this example, the charging cells202are arranged end-to-end without overlap. This arrangement can be provided without through-holes or wire interconnects. Other arrangements are possible, including arrangements in which some portion of the charging cells202overlap. For example, wires of two or more coils may be interleaved, arranged concentrically or overlaid to some extent.

FIG. 3illustrates an example of an arrangement of charging cells from two perspectives300,310when multiple layers are overlaid within a segment or portion of a charging surface that may be adapted in accordance with certain aspects disclosed herein. In this example, four layers of charging cells302,304,306,308are provided within the charging surface. The charging cells within each layer of charging cells302,304,306,308are arranged according to a honeycomb packaging configuration. In one example, the layers of charging cells302,304,306,308may be formed on a printed circuit board that has four or more copper layers. The arrangement of charging cells100can be selected to provide complete coverage of a designated charging area that is adjacent to the illustrated segment.

FIG. 4illustrates the arrangement of power transfer areas defined or configured in a charging surface400provided by a charging system in accordance with certain aspects disclosed herein. The illustrated charging surface400is constructed using four layers of charging cells402,404,406,408. InFIG. 4, each power transfer area provided by a charging cell in the first layer of charging cells402is marked “L1”, each power transfer area provided by a charging cell in the second layer of charging cells404is marked “L2”, each power transfer area provided by a charging cell in the third layer of charging cells406is marked “L3”, and each power transfer area provided by a charging cell in the fourth layer of charging cells408is marked “L4”.

Wireless Transmitter

FIG. 5illustrates certain aspects of a wireless transmitter500that can be provided in a base station of a wireless charging device. A base station in a wireless charging device may include one or more processing circuits used to control operations of the wireless charging device. A controller502may receive a feedback signal filtered or otherwise processed by a filter circuit508. The controller may control the operation of a driver circuit504that provides an alternating current to a resonant circuit506. In some examples, the controller502generates a digital frequency reference signal used to control the frequency of the alternating current output by the driver circuit504. In some instances, the digital frequency reference signal may be generated using a programmable counter or the like. In some examples, the driver circuit504includes a power inverter circuit and one or more power amplifiers that cooperate to generate the alternating current from a direct current source or input. In some examples, the digital frequency reference signal may be generated by the driver circuit504or by another circuit. The resonant circuit506includes a capacitor512and inductor514. The inductor514may represent or include one or more transmitting coils in a charging cell that produce a magnetic flux responsive to the alternating current. The resonant circuit506may also be referred to herein as a tank circuit, LC tank circuit, or LC tank, and the voltage516measured at an LC node510of the resonant circuit506may be referred to as the tank voltage.

Passive ping techniques may use the voltage and/or current measured or observed at the LC node510to identify the presence of a receiving coil in proximity to the charging pad of a device adapted in accordance with certain aspects disclosed herein. Some conventional wireless charging devices include circuits that measure voltage at the LC node510of the resonant circuit506or the current in the resonant circuit506. These voltages and currents may be monitored for power regulation purposes and/or to support communication between devices. According to certain aspects of this disclosure, voltage at the LC node510in the wireless transmitter500illustrated inFIG. 5may be monitored to support passive ping techniques that can detect presence of a chargeable device or other object based on response of the resonant circuit506to a short burst of energy (the ping) transmitted through the resonant circuit506.

A passive ping discovery technique may be used to provide fast, low-power discovery. A passive ping may be produced by driving a low-energy, fast pulse through a network that includes the resonant circuit506with a fast pulse that includes a small amount of energy. The fast pulse excites the resonant circuit506and causes the network to oscillate at its natural resonant frequency until the injected energy decays and is dissipated. The response of a resonant circuit506to a fast pulse may be determined in part by the resonant frequency of the resonant LC circuit. A response of the resonant circuit506to a passive ping that has initial voltage (V0) may be represented by the voltage VLCobserved at the LC node510, such that:

Voltage or current in the resonant circuit506may be monitored when the controller502or another processor is using digital pings to detect presence of objects. A digital ping is produced by driving the resonant circuit506for a period of time. The resonant circuit506is a tuned network that includes a transmitting coil of the wireless charging device. A receiving device may modulate the voltage or current observed in the resonant circuit506by modifying the impedance presented by its power receiving circuit in accordance with signaling state of a modulating signal. The controller502or other processor then waits for a data modulated response that indicates that a receiving device is nearby.

Selectively Activating Coils

According to certain aspects disclosed herein, power transmitting coils in one or more charging cells may be selectively activated to provide an optimal electromagnetic field for charging a compatible device. In some instances, power transmitting coils may be assigned to charging cells, and some charging cells may overlap other charging cells. The optimal charging configuration may be selected at the charging cell level. In some examples, a charging configuration may include charging cells in a charging surface that are determined to be aligned with or located close to the device to be charged. A controller may activate a single power transmitting coil or a combination of power transmitting coils based on the charging configuration which in turn is based on detection of location of the device to be charged. In some implementations, a wireless charging device may have a driver circuit that can selectively activate one or more power transmitting coils or one or more predefined charging cells during a charging event.

FIG. 6illustrates a first topology600that supports matrix multiplexed switching for use in a wireless charging device adapted in accordance with certain aspects disclosed herein. The wireless charging device may select one or more charging cells100to charge a receiving device. Charging cells100that are not in use can be disconnected from current flow. A relatively large number of charging cells100may be used in the honeycomb packaging configuration illustrated inFIGS. 2 and 3, requiring a corresponding number of switches. According to certain aspects disclosed herein, the charging cells100may be logically arranged in a matrix608having multiple cells connected to two or more switches that enable specific cells to be powered. In the illustrated first topology600, a two-dimensional matrix608is provided, where the dimensions may be represented by X and Y coordinates. Each of a first set of switches606is configured to selectively couple a first terminal of each cell in a column of cells to a first terminal of a voltage or current source602that provides current to activate coils in one or more charging cells during wireless charging. Each of a second set of switches604is configured to selectively couple a second terminal of each cell in a row of cells to a second terminal of the voltage or current source602. A charging cell is active when both terminals of the cell are coupled to the voltage or current source602.

The use of a matrix608can significantly reduce the number of switching components needed to operate a network of tuned LC circuits. For example, N individually connected cells require at least N switches, whereas a two-dimensional matrix608having N cells can be operated with √N switches. The use of a matrix608can produce significant cost savings and reduce circuit and/or layout complexity. In one example, a 9-cell implementation can be implemented in a 3×3 matrix608using 6 switches, saving 3 switches. In another example, a 16-cell implementation can be implemented in a 4×4 matrix608using 8 switches, saving 8 switches.

During operation, at least 2 switches are closed to actively couple one coil or charging cell to the voltage or current source602. Multiple switches can be closed at once in order to facilitate connection of multiple coils or charging cells to the voltage or current source602. Multiple switches may be closed, for example, to enable modes of operation that drive multiple transmitting coils when transferring power to a receiving device.

FIG. 7illustrates a second topology700in which each individual coil or charging cell is directly driven by a driver circuit702in accordance with certain aspects disclosed herein. The driver circuit702may be configured to select one or more coils or charging cells100from a group of coils704to charge a receiving device. It will be appreciated that the concepts disclosed here in relation to charging cells100may be applied to selective activation of individual coils or stacks of coils. Charging cells100that are not in use receive no current flow. A relatively large number of charging cells100may be in use and a switching matrix may be employed to drive individual coils or groups of coils. In one example, a first switching matrix may configure connections that define a charging cell or group of coils to be used during a charging event and a second switching matrix may be used to activate the charging cell and/or group of selected coils.

FIG. 8illustrates a charging cell layout800configured in accordance with certain aspects of this disclosure. In the illustrated example, the charging cell layout800is provided using a four-layer structure implemented on the metal layers of a pair of two-layer printed circuit boards (PCBs)822or824that are bonded or joined by an insulating adhesive layer826. In other examples, the four-layer structure may be implemented on the metal layers of a single four-layer printed circuit board (PCB). In the illustrated example, an active charging cell802is provided on a first layer of a four-layer structure and charging cells804,806,808provided on the other three layers may have windings that overlap the windings of the active charging cell802. In one example, each charging cell includes a transmitting coil that has a winding formed as a decreasing radius trace812or816on one side of a PCB822or824, with the winding being concentric with and/or surrounding a power transfer area (seeFIG. 1). In one example, the decreasing radius trace812has a substantially smooth curved spiral shape. In another example, the decreasing radius trace816is segmented and generally hexagonal in shape. The decreasing radius traces812and816may be provided adjacent a magnetic core material814and818, respectively. The magnetic core material814and818may be formed from a low coercivity material such as a soft ferrite. In one example, the magnetic core material814and818is integrated in an adhesive layer. In another example, the magnetic core material814and818may be attached to an adhesive layer or sandwiched between adhesive layers.

A partial view820of a lateral cross-section810of the two-layer PCBs822or824illustrates further aspects of charging cell layout800. In some examples, a charging cell804in the second layer, a charging cell806in the third layer and a charging cell808in the second layer partially overlap the active charging cell802. Areas of the metal layers832,834,836and838occupied by windings are shown in solid black, with individual traces not being explicitly shown. Each of the metal layers832,834,836and838is provided on a side of a PCB822or824. A planar magnetic core842is provided between the two adjacent metal layers834and836of the PCBs822and824. The planar magnetic core842may be included in an adhesive layer or between adhesive layers826,828. The planar magnetic core842and the adhesive layers826,828are electrically non-conductive.

Certain challenges are associated with single-coil and multi-coil wireless charging systems that employ transmitting coils formed on PCBs. These challenges can include inefficient power delivery due to the current carrying capabilities of traces that form or supply the transmitting coils, skin effects, eddy currents induced from adjacent windings, and other electromagnetic issues. Skin effect losses occur in traces or wires carrying high frequency signals where the current tends to flow at outermost reaches (skin) of the trace or wire. The concentration of current in the skin of the trace or wire can effectively increase resistance of the trace or wire due to a reduction in the percentage of cross-sectional area of the trace or wire that is used to carry high-frequency AC current. Increasing demands for higher rates of power transfer in wireless charging devices can be at least partially met by improving the efficiency of power transmission through the transmitting coils of a wireless charging device. Earlier generations of receiving devices may demand up to 5 W maximum from the transmitter, while later generations of receiving devices can demand 15 W or more to expedite the charging process. Losses associated with increased power transmission levels often manifest in increased thermal generation and charging devices that supply power at high levels are generally required to dissipate heat efficiently or throttle power transmissions as heat builds in the charging device or the power receiving device.

Certain aspects of this disclosure enable wireless charging devices to improve the efficiency of wireless power transfers to receiving devices while mitigating thermal issues. Transmitted power may be increased through improvements to transmitting coil design and associated manufacturing techniques. In one aspect of this disclosure, transmitting coils may be formed from multi-stranded wires that exhibit reduced losses and can thereby reduce heat generation during power transmission. A wireless charging device may employ multiple wire-formed transmitting coils that can be assembled and maintained in alignment using a substrate that receives and maintains the coils in preassigned three-dimensional (3D) locations.

FIG. 9illustrates an example of a transmitting coil configured in accordance with certain aspects of this disclosure. The transmitting coil may be wound from a multi-stranded Litz wire904and may be referred to as a Litz coil900. Each strand906of the Litz wire904is formed as an insulated conductor that is sufficiently thin to mitigate or substantially reduce skin effect loss. Skin effect losses occur in wires carrying high frequency signals where the current tends to flow at outermost reaches (skin) of the wire. The strands906in the Litz wire904are insulated to maintain their individual nature and are twisted such that the relative positioning of the individual strands906changes over the length of the Litz wire904. In some instances, the strands906are bound by an exterior insulating layer908. The Litz coil900is wound as a substantially planar coil with an open interior that corresponds to the power transfer area902.

FIG. 10illustrates an example of a portion of a charging surface1000provided by multiple overlapping Litz coils900. In the illustrated example, the charging surface1000is constructed using three layers of Litz coils900, although the number of layers of Litz coils900and arrangement of the Litz coils900in the charging surface1000may vary according to application, size of the charging surface1000and power transfer requirements per Litz coil900.

The configuration of Litz coils900in a charging surface1000may be precisely defined by design requirements. The number of Litz coils900to be assembled may be difficult to manage and align and variability in positioning of the Litz coils900can result in imprecise configurations of coils in some finished devices. In some instances, the Litz coils900may be retained in position using an adhesive or epoxy resin. However, the Litz coils900must be accurately positioned before application of the adhesive or resin and movement caused during application of the adhesive or resin may affect the operation of the finished wireless charging device. According to certain aspects of this disclosure, a substrate is provided to receive the Litz coils900and the substrate may be configured to maintain the Litz coils900in a desired configuration for the lifetime of the wireless charging device.

FIG. 11provides a transparent view1100of Litz coils maintained within a Litz coil substrate used to provide a charging surface of a wireless charging device in accordance with certain aspects of this disclosure. The exploded view1120shows a Litz coil substrate1122configured to receive Litz coils and maintain the Litz coils in a predefined multi-layer Litz coil structure1124with 3D displacements between coils that meet tolerances defined by a designer. The Litz coil substrate1122may also define the spatial relationship between the multi-layer Litz coil structure1124and a ferrite layer1126or another type of magnetic half-core.

FIG. 12illustrates certain aspects of a Litz coil substrate1200provided in accordance with certain aspects of this disclosure. The Litz coil substrate1200may be formed from a polymer, acetate, vinyl, nitrile rubber, latex, extruded polystyrene foam and/or another type of material. The Litz coil substrate1200can have multiple cutouts that enable the Litz coils900to be placed in position in an ordered assembly. In some examples, the cutouts may be formed during manufacture when the Litz coil substrate1200is fabricated by 3D printing, molding, extrusion and/or low-pressure expansion. In some examples, the cut-outs may be provided by milling, grinding, etching, abrading, chemical erosion, chemical dissolution or by another technique suitable for use with the material used to form the Litz coil substrate1200.

Certain aspects of the Litz coil substrate1200are illustrated in a cross-sectional view1220. The illustrated Litz coil substrate1200provides a four-layer charging surface and the cross-sectional view1220illustrates an example of placement and assembly of four Litz coils1224a-1224d. The Litz coil substrate1200has a deep, first cutout1226ain the Litz coil substrate1200that receives a first Litz coil1224a. This first cutout1226amay be formed as a complete circle in some examples. In other examples, the first cutout1226amay overlap with another cutout in the same plane of the Litz coil substrate1200.

When the first Litz coil1224ahas been secured within the first cutout1226a, a second Litz coil1224bmay be placed in a second cutout1226bin the Litz coil substrate1200. When in position within the Litz coil substrate1200, the second Litz coil1224blies in a plane above the plane that includes the first Litz coil1224a. A portion of the second Litz coil1224boverlaps a portion of the first Litz coil1224a. The separation of the planes that include the horizontal center lines of the first Litz coil1224aand the second Litz coil1224bmay be configured or defined based on the relative difference in depths of the first cutout1226aand the second cutout1226b.

The third Litz coil1224cis received by a deep, third cutout1226cin the Litz coil substrate1200. This third cutout1226cmay be formed as a complete circle in some examples. In other examples, the third cutout1226cmay overlap with another cutout in the same plane. In one example, the third cutout1226cmay partially overlap the first cutout1226aresulting in a through-hole, when the bottom surface of the first Litz coil1224ais in the same plane as the top surface or some other portion of the third Litz coil1224c.

When the third Litz coil1224chas been secured within the third cutout1226c, a fourth Litz coil1224dmay be placed in a fourth cutout1226d. The fourth Litz coil1224dlies in a plane below the plane that includes the third Litz coil1224c. A portion of the fourth Litz coil1224doverlaps a portion of the third Litz coil1224cwhen secured within the Litz coil substrate1200. The separation of the planes that include the horizontal center lines of the third Litz coil1224cand the fourth Litz coil1224dmay be configured by the relative difference in depths of the third cutout1226cand the fourth cutout1226d.

The Litz coil1224a-1224dmay be secured within the Litz coil substrate1200through a pressure fit, including when the Litz coil substrate1200is manufactured from a foam material. In some examples, the Litz coil1224a-1224dmay be secured within the Litz coil substrate1200by adhesive. In some examples, the Litz coil1224a-1224dmay be secured within the Litz coil substrate1200by mechanical means.

Certain aspects of this disclosure provide techniques for mitigating thermal issues in wireless charging devices, including wireless charging devices that employ Litz coils. A wireless charging system adapted in accordance with certain aspects of this disclosure can exhibit improved efficiencies in power usage over conventional systems. The improvements in efficiency obtained from the use of Litz coils and other mechanical and electromagnetic design techniques may be offset or limited by other inefficiencies in the wireless charging system that cause heat generation in the wireless charging system. In some instances, overall efficiency of a wireless charging system may not exceed 50% in some use cases. Inefficiencies can arise from losses due to eddy currents induced in packaging, PCBs, interconnects, fasteners and in circuit boards. Inefficiencies can arise in voltage conversion circuits. Conventional thermal management systems typically control heat generation by selectively reducing power transmissions when increases in temperature are detected. Unmitigated heat induced in the transmitting coils, driver circuits and housings of the wireless charging device and in the receiving coil, receiving circuits and casing of device being charged can limit the power transfer levels available to the wireless charging system. Inadequate thermal management can increase the time to charge a device when power transmissions are throttled to avoid excessive heat accumulation. The effects of inadequate thermal management can be perceived as a performance issue of the wireless charging system.

According to certain aspects of this disclosure, a wireless charging system may be configured to receive a flow of cooling fluid and to direct the flow to heat accumulating elements and surfaces of the wireless charging device and, in some instances, to a surface of a device being charged. Cooled or forced air may be used as the cooling fluid. In some examples, an airflow may be forced by a fan, bladeless fan or electrostatic blower. In some examples, the airflow may be passed through or received from an air conditioning system.

FIG. 13is a cross-sectional view that illustrates an example of a multi-coil free-positioning wireless charging device1300configured in accordance with certain aspects of this disclosure. The wireless charging device1300may be adapted to receive and conduct an airflow through certain structures, cavities, layers, substrates and/or circuits in the wireless charging device1300. In the illustrated example, a first two-layer PCB1304provides transmitting coils1302a,1302b,1302carranged across a top layer of the first two-layer PCB1304. A second two-layer PCB1308provides transmitting coils1306a,1306b, arranged across a top layer of the second two-layer PCB1308. The example of a two PCB implementation is used herein to facilitate description of certain cooling techniques but other combinations and configurations of PCBs may be employed in various implementations. In other examples instances, transmitting coils may be provided on top and bottom layers of the first two-layer PCB1304and/or the second two-layer PCB1308.

The top layer of the first two-layer PCB1304may be configured to provide a charging surface of the wireless charging device1300. For example, the top layer of the first two-layer PCB1304may be coated with a conformal coating or other overlay1318. The PCBs1304,1308may be mechanically coupled or may be joined using one or more adhesive layers1312and a spacer layer1314. A spacer layer1316is also shown at the bottom of the second PCB1308.

In some implementations, the adhesive layer1312may be multi-layered or multifaceted. In one example, the adhesive layer1312is a compound layer that includes a ferrite layer, an electrical insulating layer and/or a thermally insulating layer. In one example, the adhesive layer1312is a compound layer that provides partial ferrite or insulating layers located based on the position of one or more transmitting coils1302a,1302b,1302c,1306a,1306b.

Horizontal ducts (referred to herein as channels) may be formed or fabricated within the spacer layers1314,1316. In some instances, the channels are configured to interconnect with vertical ducts1320a-1320e. One or more airflows1310a,1310b,1310creceived from an entrance port (not shown) may be conducted through the channels and through the vertical ducts1320a-1320ebefore exiting through an exit port (not shown). The airflows1310a-1310cmay be configured to remove heat from the surfaces of the PCBs1304,1308, from the transmitting coils1302a,1302b,1302c,1306a,1306band/or from the charging surface of the wireless charging device1300.

In some implementations, the conformal coating or other overlay1318comprises a thermally conductive material and, together with one or more airflows1310a,1310b,1310c, can facilitate the dissipation of heat generated in a device being charged or generated at the physical interface between the device being charged and the charging surface of the wireless charging device1300. In some instances, the conformal coating or other overlay1318includes a porous material that allows the airflows1310a-1310cto vent, at least partially, towards a device being charged. The porous material may include non-electrically conductive materials such as Polytetrafluoroethylene (PTFE) or the like.

FIG. 14illustrates certain aspects of a Litz coil substrate1400configured to facilitate removal of heat in accordance with certain aspects of this disclosure. The Litz coil substrate1400may be formed from a polymer, acetate, vinyl, nitrile rubber, latex, extruded polystyrene foam and/or another type of material. The Litz coil substrate1400may have multiple cutouts that enable the Litz coils900to be placed in position in an ordered assembly. In some examples, the cut-outs may be preformed when the Litz coil substrate1400is manufactured by 3D printing, molding, extrusion and/or low-pressure expansion. In some examples, the cut-outs may be formed by milling, grinding, etching, abrading, chemical erosion, chemical dissolution or by another technique suitable for use with the material used to form the Litz coil substrate1400.

Certain aspects of the Litz coil substrate1400are illustrated in a cross-sectional view1420. The illustrated Litz coil substrate1400provides a four-layer charging surface and the cross-sectional view1420illustrates an example of placement and assembly of four Litz coils1424a-1424din the wireless charging device, which is illustrated generally at1440. The Litz coil substrate1400has a deep, first cutout1426ain the Litz coil substrate1400that receives a first Litz coil1424a. This first cutout1426amay be formed as a complete circle in some examples. In other examples, the first cutout1426amay overlap with another cutout in the same plane of the Litz coil substrate1400.

When the first Litz coil1424ahas been secured within the first cutout1426a, a second Litz coil1424bmay be placed in a second cutout1426bin the Litz coil substrate1400. When in position within the Litz coil substrate1400, the second Litz coil1424blies in a parallel plane positioned above the plane that includes the first Litz coil1424a. A portion of the second Litz coil1424boverlaps a portion of the first Litz coil1424a. The separation of the planes that include the horizontal center lines of the first Litz coil1424aand the second Litz coil1424bmay be configured by the relative difference in depths of the first cutout1426aand the second cutout1426b.

The third Litz coil1424cis received by a deep, third cutout1426cin the Litz coil substrate1400. This third cutout1426cmay be formed as a complete circle in some examples. In other examples, the third cutout1426cmay overlap with another cutout in the same plane. In one example, the third cutout1426cmay partially overlap the first cutout1426aresulting in a through-hole, when the bottom surface of the first Litz coil1424ais in the same plane as the top surface or some other portion of the third Litz coil1424c.

When the third Litz coil1424chas been secured within the third cutout1426c, a fourth Litz coil1424dmay be placed in a fourth cutout1426d. The fourth Litz coil1424dlies in a plane below the plane that includes the third Litz coil1424c. A portion of the fourth Litz coil1424doverlaps a portion of the third Litz coil1424cwhen secured within the Litz coil substrate1400. The separation of the planes that include the horizontal center lines of the third Litz coil1424cand the fourth Litz coil1424dmay be configured by the relative difference in depths of the third cutout1426cand the fourth cutout1426d.

The Litz coil1424a-1424dmay be secured within the Litz coil substrate1400through a pressure fit, including when the Litz coil substrate1400is manufactured from a foam material. In some examples, the Litz coil1424a-1424dmay be secured within the Litz coil substrate1400by adhesive. In some examples, the Litz coil1424a-1424dmay be secured within the Litz coil substrate1400by mechanical means.

A system of interconnecting channels or ducts1428can be seen in the cross-sectional view1420. In one example, horizontal ducts (referred to herein as channels) interconnect with vertical ducts. The system of interconnecting channels or ducts1428may be configured to direct or conduct a received airflow1442around or through the Litz coils1424a-1424dand toward the charging surface of the wireless charging device. With reference to the two-dimensional transparent view1440, the airflow1442may be received through an entrance port1444and may be conducted through the system of interconnecting channels or ducts1428before exiting as an exhaust flow1446through an exit port1448. In one example, the entrance port1444and/or the exit port1448comprise a threaded pipe configured to couple the airflow1442and the exhaust flow1446to an external cooling or ventilation system as found, for example, in an automobile, bus, train, airplane, seagoing vessel or other vehicle. In other examples, the entrance port1444and/or the exit port1448is part of a snap-fit coupling or a coupling that is secured using an elastic material such as a rubber, latex or synthetic rubber material. The air flowing through the interconnecting channels or ducts1428can remove heat from the surfaces of the Litz coils1424a-1424d, the Litz coil substrate1400and from one or more surfaces of the wireless charging device.

FIG. 15shows a system1500in which a coupling mechanism1508is used to provide a wireless charging device1502with an airflow1504received from an air-conditioning system or the like. The system1500may be deployed in an automobile, bus, train, airplane, seagoing vessel or other vehicle that provides air conditioning, forced-air ventilation or another source of airflow. The wireless charging device1502may include interconnecting channels or ducts of the type illustrated inFIGS. 13 and 14, for example. Alternatively, or additionally, the wireless charging device1502may include an open area, channel or duct that provides the airflow on or around a processing circuit1514or a current driving circuit in the wireless charging device1502. In the illustrated example, the exhaust airflow is vented through a port1512to the exterior of the wireless charging device1502. In other examples, the exhaust airflow may be recovered by an air conditioning system.

The coupling mechanism1508may be configured to mechanically secure the wireless charging device1502to the source of airflow. In the illustrated example, the coupling system provides a snap-fit coupling, a screw-fit coupling or a coupling that is secured using an elastic material such as a rubber, latex or synthetic rubber material. In one example, the coupling mechanism1508includes a rubber receptacle1510fixed to the wireless charging device1502and configured to engage a metal, ceramic or polymer nozzle or funnel1506through which the airflow is delivered. The exhaust airflow may be vented through the port1512to the exterior of the wireless charging device1502, through a porous material on the surface1516of the wireless charging device1502, through a return connection to the source of the airflow, or through other mechanisms or conduits.

In some instances, the coupling mechanism1508may have sufficient mechanical strength to operate as a mount for the wireless charging device1502.

FIG. 16shows a system1600in which a wireless charging device1602receives a flow of air1604from an air-conditioning system, ventilation system or other source of forced air. In certain examples, the system1600may be deployed in an automobile, bus, train, airplane, seagoing vessel or other vehicle that provides air conditioning or forced air ventilation. The wireless charging device1602may include interconnecting channels or ducts as illustrated inFIGS. 13 and 14, for example. Alternatively, or additionally, the wireless charging device1602may include an open area, channel or duct configured to direct airflow onto or around a processing circuit1612or current driving circuit in the wireless charging device1602.

In the illustrated example, multiple airflows1608,1610are directed toward the exterior of the wireless charging device1602. One or more of the airflows1608,1610may be directed toward an open input port of the wireless charging device1602such that the wireless charging device1602receives an inflow of cooling air into an open area, channel or duct. In the illustrated example, the airflows1608,1610are provided by some combination of nozzles or vents in a manifold1606that is configured to distribute a flow of air1604received from the air-conditioning system, ventilation system or other source of forced air. Elongated nozzles or vents1614provided along a side of the wireless charging device1602may direct a broad flow of air across the surface of the wireless charging device1602.

FIG. 17shows a combination system1700in which a wireless charging device1702is coupled to the inflow of air1704received from an air-conditioning system, ventilation system or other source of forced air. A first vent, duct or nozzle is configured or arranged to direct a portion of the inflow of air1704as an external airflow1708that is directed onto an exterior surface of the wireless charging device1702. A second duct or nozzle is configured to introduce a portion of the inflow of air1704directly into the interior of the wireless charging device1702. The combination system1700may be deployed in an automobile or other type of vehicle that provides air conditioning or a source of airflow. The wireless charging device1702may include interconnecting channels or ducts as illustrated inFIGS. 13 and 14, for example. Alternatively, or additionally, the wireless charging device1702may include an open area, channel or duct that provides the airflow on or around a processing circuit or a current driving circuit in the wireless charging device1702.

A coupling system1710may secure the wireless charging device1702to a manifold1706that distributes the inflow of air1704. The coupling system1710may comprise a snap-fit coupling, a screw-fit coupling or a coupling that is secured through an elastic material such as a rubber, latex or synthetic rubber material. In one example, the coupling system1710includes a rubber receptacle fixed to the wireless charging device1702and configured to engage a metal, ceramic or polymer nozzle or funnel through which the airflow is delivered. The airflow may be vented by the wireless charging device1702through an exit port, through a porous material on the surface1712of the wireless charging device1702, through a return connection to the source of the airflow, or by other means. In other examples, the airflow may be recovered by an air conditioning system.

One or more airflows1708may be directed toward the exterior of the wireless charging device1702. In one example, the external airflow1708is directed toward an input port of the wireless charging device1702such that the wireless charging device1702receives an inflow of cooling air into an open area, channel or duct. In another example, the external airflow1708is directed toward a charging surface1712of the wireless charging device1702such that the surface of the wireless charging device1702and any device being charged receive an inflow of cooling air. The external airflow1708may be received from some combination of nozzles or vents supplied by the manifold1706. Elongated nozzles or vents provided along a side of the wireless charging device1702may direct a broad flow of air across the surface of the wireless charging device1702. In some instances, the manifold1706may have sufficient mechanical strength to operate as a mount for the wireless charging device1702.

According to certain aspects of this disclosure, a wireless charging device may be equipped with a cooling fan, impeller or blower. In some examples, the wireless charging device may be deployed or installed in a vehicle that provides a tight or relatively small volume space for installing the wireless charging device. The cooling fan, impeller or blower may be activated without significantly increasing ambient noise within a passenger cabin of the vehicle.

FIG. 18provides a view of a first side of a wireless charging device1800that can be cooled by a forced air flow produced by an external fan1806. The wireless charging device1800may be configured to operate as a multi-coil free-positioning wireless charging system. The external fan1806is located on an outer surface of the wireless charging device1800.

In the illustrated example, the wireless charging device1800has a housing that includes a front portion1802and back or rear portion1804. The external fan1806may comprise an axial fan configured to drive an airflow into the wireless charging device1800or pull an exhaust airflow from the interior of the wireless charging device1800. The external fan1806may be directly mounted to the rear portion1804. In some examples, the rear portion1804is constructed, at least in part, from a metal such as aluminum or copper that can assist heat dissipation. In the illustrated example, the external fan1806is mounted on the outside of an aluminum rear portion1804of the housing. A configuration having an externally-mounted fan can support fan types that have a profile or height that are not suited for inclusion within the housing. In some examples, an externally-mounted fan has a 50 mm×50 mm cross-sectional area and a height that can vary from 10 mm to 32 mm. The physical dimensions of the illustrated external fan1806may be determined by the volume of air to be moved by the external fan1806. In some examples the volume of air moved by the external fan1806is measured or characterized as cubic feet per minute (CFM). In one example, a 50 mm×50 mm axial fan can produce airflow at up to 31.6 CFM. In the latter example, an axial fan can be operated at variable power to produce between 6.3 CFM and 31.6 CFM.

FIG. 19provides a view of a second side of a wireless charging device1900that can be cooled by a forced air flow produced by an external fan1906. The wireless charging device1900may correspond to the wireless charging device1800ofFIG. 18and may be configured to operate as a multi-coil free-positioning wireless charging system. The external fan1906is located on an outer surface of the wireless charging device1900.

In the illustrated example, the wireless charging device1900has a housing that includes a front portion1902and back or rear portion1904. Here the rear portion1904is adapted or configured to assist air flow. In the drawing, the front portion1902is illustrated as a transparent component, exposing certain internal features of the rear portion1904.

The external fan1906may comprise an axial fan configured to drive an airflow into the wireless charging device1900or to pull an exhaust airflow from the interior of the wireless charging device1900. The external fan1906may be directly mounted to the rear portion1904. In some examples, the rear portion1904includes or is constructed from a metal such as aluminum or copper that can assist heat dissipation. In the illustrated example, the fan1906is mounted within the housing.

The internal surface of the rear portion1904may be configured with channels1910or grooves that conduct air flowing from the fan1906across an area corresponding to the transmitting coils, current generation circuits and controllers of the wireless charging device1900. In some examples, the channels1910provide a pathway to a slotted, elongated opening on the rear portion1904that operates to vent an outflow1908of air received from the channels1910. The width, height and routing of the channels1910can be configured according to airflow needs or requirements.

FIG. 20provides a view of a first side of a wireless charging device2000that can be cooled by a forced air flow produced by one or more internal impeller fans2006,2008. The wireless charging device2000may be configured to operate as a multi-coil free-positioning wireless charging system. The internal impeller fans2006,2008may be located largely within the housing of wireless charging device2000.

In the illustrated example, the wireless charging device2000has a housing that includes a front portion2002and back or rear portion2004, and active cooling is achieved using two internal impeller fans2006,2008that can be mounted adjacent to the inner surface of the rear portion2004. In some examples, the rear portion2004includes or is constructed from a metal such as aluminum or copper that can assist heat dissipation. In the illustrated example, the mounting of the internal impeller fans2006,2008on the inside of housing can limit the types and sizes of fan that can be used. In some examples, more than two internal impeller fans2006,2008may be provided in the wireless charging device2000. In some instances, the number of active internal impeller fans2006,2008may be dynamically configured to produce a desired or required maximum airflow. In some instances, the speed of operation of the internal impeller fans2006,2008may be dynamically configured to produce a desired or required maximum airflow.

FIG. 21provides a view of a second side of a wireless charging device2100that can be cooled by a forced air flow produced by one or more internal impeller fans2106,2108. The wireless charging device2100may correspond to the wireless charging device2000ofFIG. 20and may be configured to operate as a multi-coil free-positioning wireless charging system. The internal impeller fans2106,2108may be located largely within the housing of wireless charging device2100.

In the illustrated example, the wireless charging device2100has a housing that includes a front portion2102and back or rear portion2104. The front portion2102and/or the back or rear portion2104may be adapted or configured to assist air flow. In the drawing, the front portion2102is illustrated as a transparent component, thereby exposing certain internal features of the rear portion2104.

The internal impeller fans2106,2108may be directly mounted to the rear portion2104.

In some examples, the rear portion2104includes or is constructed from a metal such as aluminum or copper that can assist heat dissipation. The internal surface of the rear portion2104may be configured with channels or grooves that conduct air flowing from the internal impeller fans2106,2108across an area corresponding to the transmitting coils, current generation circuits and controllers of the wireless charging device2100. In some examples, the channels provide a pathway to a slotted, elongated opening on the rear portion2104that operates to vent an outflow of air received from the air channels. The width, height and routing of the air channels can be configured according to airflow needs or requirements.

FIG. 22provides a side view of a multi-coil free-positioning wireless charging device2200that can be cooled by a forced airflow produced by a fan assembly2208that is located largely within the housing of wireless charging device2200. The fan assembly2208may comprise one or more internal impeller fans. In the illustrated example, the wireless charging device2200has a housing that includes a front portion2202and back or rear portion2204. The front portion2202and/or the back or rear portion2204may be adapted or configured to assist air flow. The wireless charging device2200may correspond to a wireless charging device2000or2100illustrated in any ofFIGS. 18-21.

An air intake and/or the fan assembly2208may be configured to receive an inflow2212of air. In the illustrated example, impellers in the fan assembly2208force air directly over internal components including transmitting coils, current generation circuits and controllers of the wireless charging device2300or2100through air channels configured in accordance with certain aspects of this disclosure.

FIG. 23illustrates an example of a multi-coil free-positioning wireless charging device2300that can be cooled by a forced airflow attachment. Here the airflow is produced by a separate, attachable cooling device2310that can be attached to the wireless charging device2300and that operates as a funnel. In the illustrated example, the wireless charging device2300has a housing that includes a front portion2302and back or rear portion2304, and the attachable cooling device2310may be configured to mounted on the housing of the wireless charging device2300using snap fit structures or fasteners.

The airflow may be produced by one or more fans2308that drive air through the funnel to outlets2312,2314,2316that are configured to direct air toward a charging surface of the wireless charging device2300and/or any receiving devices being charged by the wireless charging device2300. The cooling device2310may provide bottom or top outlets2312and side outlets2314,2316. In some examples, the cooling device2310may include or may be constructed from a polymer or a metal such as aluminum or copper that can assist heat dissipation.

FIG. 24provides a reverse view of an attachable cooling device2400that may correspond in some respects to the wireless charging device2300illustrated inFIG. 23. Outlets2404,2406,2408in the attachable cooling device2400may direct air on to or across a gap provided at a surface2402configured to interface with a charging surface of an attached wireless charging device.

FIG. 25provides a side view of a wireless charging device2500that may correspond in some respects to the wireless charging device2300illustrated inFIG. 23. A side outlet2508in the cooling device2510may direct air on to or across a charging surface2502of the wireless charging device2500and onto a receiving device2504being charged by the wireless charging device2500.

FIG. 26illustrates an example in which a multi-coil free-positioning wireless charging device2600can be cooled by a hybrid forced airflow. Here, airflows are provided by one or more impeller fans2606located largely within the housing of wireless charging device2600and by a separate, attachable cooling device2608that operates as a funnel.

In the illustrated example, the wireless charging device2600has a housing that includes a front portion2602and back or rear portion2604, and active cooling is achieved using a pair of impeller fans2606that can be mounted adjacent to the inner surface of the rear portion2604. In some examples, the rear portion2604includes or is constructed from a metal such as aluminum or copper that can assist heat dissipation.

The cooling device2608may operate as a funnel and may be fitted to the housing of the wireless charging device2600using snap fit structures or fasteners. The cooling device2608can produce an airflow using one or more fans that drive air through the funnel to outlets2610,2612that are configured to direct air toward a charging surface of the wireless charging device2600and/or any receiving devices being charged by the wireless charging device2600. In some examples, the cooling device2608may include or may be constructed from a polymer or a metal such as aluminum or copper that can assist heat dissipation.

Example of a Processing Circuit

FIG. 27illustrates an example of a hardware implementation for an apparatus2700that may be incorporated in a charging device or in a receiving device that enables a battery to be wirelessly charged. In some examples, the apparatus2700may perform one or more functions disclosed herein. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements as disclosed herein may be implemented using a processing circuit2702. The processing circuit2702may include one or more processors2704that are controlled by some combination of hardware and software modules. Examples of processors2704include microprocessors, microcontrollers, digital signal processors (DSPs), SoCs, ASICs, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, sequencers, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. The one or more processors2704may include specialized processors that perform specific functions, and that may be configured, augmented or controlled by one of the software modules2716. The one or more processors2704may be configured through a combination of software modules2716loaded during initialization, and further configured by loading or unloading one or more software modules2716during operation.

In the illustrated example, the processing circuit2702may be implemented with a bus architecture, represented generally by the bus2710. The bus2710may include any number of interconnecting buses and bridges depending on the specific application of the processing circuit2702and the overall design constraints. The bus2710links together various circuits including the one or more processors2704, and storage2706. Storage2706may include memory devices and mass storage devices, and may be referred to herein as computer-readable media and/or processor-readable media. The storage2706may include transitory storage media and/or non-transitory storage media.

The bus2710may also link various other circuits such as timing sources, timers, peripherals, voltage regulators, and power management circuits. A bus interface2708may provide an interface between the bus2710and one or more transceivers2712. In one example, a transceiver2712may be provided to enable the apparatus2700to communicate with a charging or receiving device in accordance with a standards-defined protocol. Depending upon the nature of the apparatus2700, a user interface2718(e.g., keypad, display, speaker, microphone, joystick) may also be provided, and may be communicatively coupled to the bus2710directly or through the bus interface2708.

A processor2704may be responsible for managing the bus2710and for general processing that may include the execution of software stored in a computer-readable medium that may include the storage2706. In this respect, the processing circuit2702, including the processor2704, may be used to implement any of the methods, functions and techniques disclosed herein. The storage2706may be used for storing data that is manipulated by the processor2704when executing software, and the software may be configured to implement any one of the methods disclosed herein.

The storage2706may maintain and/or organize software in loadable code segments, modules, applications, programs, etc., which may be referred to herein as software modules2716. Each of the software modules2716may include instructions and data that, when installed or loaded on the processing circuit2702and executed by the one or more processors2704, contribute to a run-time image2714that controls the operation of the one or more processors2704. When executed, certain instructions may cause the processing circuit2702to perform functions in accordance with certain methods, algorithms and processes described herein.

Some of the software modules2716may be loaded during initialization of the processing circuit2702, and these software modules2716may configure the processing circuit2702to enable performance of the various functions disclosed herein. For example, some software modules2716may configure internal devices and/or logic circuits2722of the processor2704, and may manage access to external devices such as a transceiver2712, the bus interface2708, the user interface2718, timers, mathematical coprocessors, and so on. The software modules2716may include a control program and/or an operating system that interacts with interrupt handlers and device drivers, and that controls access to various resources provided by the processing circuit2702. The resources may include memory, processing time, access to a transceiver2712, the user interface2718, and so on.

One or more processors2704of the processing circuit2702may be multifunctional, whereby some of the software modules2716are loaded and configured to perform different functions or different instances of the same function. The one or more processors2704may additionally be adapted to manage background tasks initiated in response to inputs from the user interface2718, the transceiver2712, and device drivers, for example. To support the performance of multiple functions, the one or more processors2704may be configured to provide a multitasking environment, whereby each of a plurality of functions is implemented as a set of tasks serviced by the one or more processors2704as needed or desired. In one example, the multitasking environment may be implemented using a timesharing program2720that passes control of a processor2704between different tasks, whereby each task returns control of the one or more processors2704to the timesharing program2720upon completion of any outstanding operations and/or in response to an input such as an interrupt. When a task has control of the one or more processors2704, the processing circuit is effectively specialized for the purposes addressed by the function associated with the controlling task. The timesharing program2720may include an operating system, a main loop that transfers control on a round-robin basis, a function that allocates control of the one or more processors2704in accordance with a prioritization of the functions, and/or an interrupt driven main loop that responds to external events by providing control of the one or more processors2704to a handling function.

In one implementation, the apparatus2700includes or operates as a wireless charging device that has a battery charging power source coupled to a charging circuit, a plurality of charging cells and a controller, which may be included in one or more processors2704. The plurality of charging cells may be configured to provide a charging surface. At least one coil may be configured to direct an electromagnetic field through a charge transfer area of each charging cell.

In one example, a wireless charging device has a plurality of planar power transmitting coils, a driver circuit and at least one substrate having one or more channels formed therein. The one or more channels may be configured to receive a flow of air at a port of entry and to conduct the flow of air through the substrate to a port of exit. The plurality of planar power transmitting coils may be supported by at least one substrate. Each planar power transmitting coil may be formed as a spiral winding surrounding a power transfer area. The driver circuit may be configured to provide a charging current to one or more of the plurality of planar power transmitting coils when a chargeable device is placed on or near the wireless charging device. The one or more channels may be configured to conduct the flow of air past or through the plurality of planar power transmitting coils and the driver circuit.

In one example, each planar power transmitting coil is formed by spiral winding a multi-strand wire, each strand in the multi-strand wire being electrically insulated from each other strand in the multi-strand wire.

In one example, the wireless charging device has a PCB that has one or more holes provided therein. The one or more holes may be configured to conduct at least a portion of the airflow between channels in two substrates.

In some examples, the wireless charging device has a coil substrate with a plurality of cut-outs formed therein. The plurality of cut-outs may be configured to secure the plurality of planar power transmitting coils in a preconfigured three-dimensional arrangement. The preconfigured three-dimensional arrangement provides a charging surface through a top surface of the coil substrate as a combination of power transfer areas of the plurality of planar power transmitting coils. A portion of the airflow may be directed toward the charging surface. The charging surface may include a porous material that passes some of the airflow that is directed toward the charging surface to the exterior of the wireless charging device. The preconfigured three-dimensional arrangement may provide planar power transmitting coils in a plurality of vertical planes.

In one example, the coil substrate is formed from a molded polymer and has one or more horizontal channels that interconnect with a plurality of vertical ducts. The one or more horizontal channels and the plurality of vertical ducts may be formed in the coil substrate during molding.

In one example, the coil substrate is formed by three-dimensional printing and includes interconnected horizontal channels and vertical ducts that are formed in the coil substrate during printing.

In one example, the coil substrate is formed from a polymer, acetate, vinyl, nitrile rubber, latex, extruded polystyrene foam and includes interconnected horizontal channels and vertical ducts that are formed in the coil substrate during printing formed milling, grinding, etching, abrading, chemical erosion or chemical dissolution.

FIG. 28is a flowchart2800illustrating a method for operating a wireless charging device. At block2802, a flow of air is provided to a port of entry of the wireless charging device. The port of entry may be fluidically coupled to one or more channels in at least one substrate of the wireless charging device. The one or more channels may be configured to conduct the flow of air through the at least one substrate to a port of exit. In one example, the flow of air is received from an air conditioning system. In another example, the flow of air is received from a fan or blower.

At block2804, a charging current is provided to one or more planar power transmitting coils supported by the at least one substrate. Each planar power transmitting coil may be formed as a spiral winding surrounding a power transfer area. At block2806, the flow of air may be directed past or through the plurality of planar power transmitting coils and a driver circuit that supplies the charging current.

In one example, each planar power transmitting coil is formed by spiral winding a multi-strand wire. Each strand in the multi-strand wire may be electrically insulated from each other strand in the multi-strand wire.

In one example, the at least one substrate includes a PCB that has one or more holes provided therethrough. The one or more holes may be configured to conduct at least a portion of the airflow between channels in two substrates.

In some examples, the at least one substrate includes a coil substrate that has a plurality of cut-outs formed therein. The plurality of cut-outs may be configured to secure the plurality of planar power transmitting coils in a preconfigured three-dimensional arrangement. The preconfigured three-dimensional arrangement may provide a charging surface through a top surface of the coil substrate as a combination of power transfer areas of the plurality of planar power transmitting coils. A portion of the airflow may be directed toward the charging surface. The charging surface may include a porous material that passes some of the airflow that is directed toward the charging surface to the exterior of the wireless charging device. The preconfigured three-dimensional arrangement may provide planar power transmitting coils in a plurality of vertical planes.

In one example, the coil substrate is formed from a molded polymer and has one or more horizontal channels that interconnect with a plurality of vertical ducts. The one or more horizontal channels and the plurality of vertical ducts may be formed in the coil substrate during molding.

In one example, the coil substrate is formed by three-dimensional printing and includes interconnected horizontal channels and vertical ducts that are formed in the coil substrate during printing.

In one example, the coil substrate is formed from a polymer, acetate, vinyl, nitrile rubber, latex, extruded polystyrene foam and includes interconnected horizontal channels and vertical ducts that are formed in the coil substrate during printing formed milling, grinding, etching, abrading, chemical erosion or chemical dissolution.

Some implementation examples are described in the following numbered clauses:1. A wireless charging device, comprising: at least one substrate having one or more channels formed therein, the one or more channels being configured to receive a flow of air and to conduct the flow of air through the at least one substrate to an outlet; a plurality of planar power transmitting coils supported by the at least one substrate, each planar power transmitting coil being formed as a spiral winding surrounding a power transfer area; and a driver circuit configured to provide a charging current to one or more of the plurality of planar power transmitting coils when a chargeable device is placed on or near the wireless charging device, wherein the one or more channels are configured to conduct the flow of air past or through the plurality of planar power transmitting coils and the driver circuit.2. The wireless charging device as described in clause 1, wherein each planar power transmitting coil is formed by spiral winding a multi-strand wire, each strand in the multi-strand wire being electrically insulated from each other strand in the multi-strand wire.3. The wireless charging device as described in clause 1 or clause 2, further comprising: a printed circuit board that has one or more holes provided therein, wherein the one or more holes are configured to conduct at least a portion of the flow of air between channels in two substrates.4. The wireless charging device as described in any of clauses 1-3, wherein the at least one substrate comprises a coil substrate having a plurality of cut-outs formed therein, the plurality of cut-outs being configured to secure the plurality of planar power transmitting coils in a preconfigured three-dimensional arrangement.5. The wireless charging device as described in clause 4, wherein the preconfigured three-dimensional arrangement provides a charging surface through a top surface of the coil substrate as a combination of power transfer areas of the plurality of planar power transmitting coils, and wherein a portion of the flow of air is directed toward the charging surface.6. The wireless charging device as described in clause 5, wherein the charging surface comprises a porous material that passes some of the flow of air that is directed toward the charging surface to the exterior of the wireless charging device7. The wireless charging device as described in clause 5 or clause 6, wherein the preconfigured three-dimensional arrangement provides planar power transmitting coils in a plurality of vertical planes.8. The wireless charging device as described in any of clauses 5-7, wherein the coil substrate is formed from a molded polymer and has one or more horizontal channels that interconnect with a plurality of vertical ducts9. The wireless charging device as described in clause 8, wherein the one or more horizontal channels and the plurality of vertical ducts are formed in the coil substrate during molding.10. The wireless charging device as described in any of clauses 5-7, wherein the coil substrate is formed by three-dimensional printing and includes interconnected horizontal channels and vertical ducts that are formed in the coil substrate during printing.11. The wireless charging device as described in any of clauses 5-7, wherein the coil substrate is formed from a polymer, acetate, vinyl, nitrile rubber, latex, extruded polystyrene foam and includes interconnected horizontal channels and vertical ducts that are formed in the coil substrate during printing formed milling, grinding, etching, abrading, chemical erosion or chemical dissolution.12. The wireless charging device as described in any of clauses 1-11, wherein the receive a flow of air is received from an internal or external fan or impeller.13. A method for operating a wireless charging device, comprising: providing a flow of air to a port of entry of the wireless charging device, the port of entry being fluidically coupled to one or more channels in at least one substrate of the wireless charging device, the one or more channels being configured to conduct the flow of air through the at least one substrate to a port of exit; providing a charging current to one or more planar power transmitting coils supported by the at least one substrate, each planar power transmitting coil being formed as a spiral winding surrounding a power transfer area; and directing the flow of air past or through the one or more planar power transmitting coils and a driver circuit that supplies the charging current.14. The method as described in clause 13, wherein each planar power transmitting coil is formed by spiral winding a multi-strand wire, each strand in the multi-strand wire being electrically insulated from each other strand in the multi-strand wire.15. The method as described in clause 13 or clause 14, wherein the at least one substrate comprises a printed circuit board that has one or more holes provided therethrough, wherein the one or more holes are configured to conduct at least a portion of the flow of air between channels in two substrates.16. The method as described in any of clauses 13-15, wherein the at least one substrate comprises a coil substrate having a plurality of cut-outs formed therein, the plurality of cut-outs being configured to secure the one or more planar power transmitting coils in a preconfigured three-dimensional arrangement.17. The method as described in clause 16, wherein the preconfigured three-dimensional arrangement provides a charging surface through a top surface of the coil substrate as a combination of power transfer areas of the one or more planar power transmitting coils, and wherein a portion of the flow of air is directed toward the charging surface.18. The method as described in clause 17, wherein the charging surface comprises a porous material that passes some of the flow of air that is directed toward the charging surface to the exterior of the wireless charging device.19. The method as described in clause 17 or clause 18, wherein the preconfigured three-dimensional arrangement provides planar power transmitting coils in a plurality of vertical planes.20. The method as described in any of clauses 17-19, wherein the coil substrate is formed from a molded polymer and has one or more horizontal channels that interconnect with a plurality of vertical ducts.21. The method as described in clause 20, wherein the one or more horizontal channels and the plurality of vertical ducts are formed in the coil substrate during molding.22. The method as described in any of clauses 13-21, wherein the coil substrate is formed by three-dimensional printing and includes interconnected horizontal channels and vertical ducts that are formed in the coil substrate during printing.23. The method as described in any of clauses 13-21, wherein the coil substrate is formed from a polymer, acetate, vinyl, nitrile rubber, latex, extruded polystyrene foam and includes interconnected horizontal channels and vertical ducts that are formed in the coil substrate during printing formed milling, grinding, etching, abrading, chemical erosion or chemical dissolution.