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

Improvements in wireless charging capabilities are required to support continually increasing complexity of mobile devices and changing form factors. For example, there is a need for improved charging techniques for multi-coil, multi-device charging pads. The document <CIT> discloses a wireless charging device including a plurality of charging coils, a plurality of position detection coils corresponding respectively to the charging coils, and a voltage monitoring circuit for measuring a coil-end voltage of each of the position detection coils. A comparison is performed between a coil-end voltage of a first position detection coil corresponding to a charging coil used for charging and a coil-end voltage of a position detection coil adjacent to the first position detection coil, and, depending on a result of the comparison, a charging coil to be used for charging is switched to an adjacent charging coil.

Several aspects of wireless charging systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawing by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements").

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.

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, inductive, touch, pressure, load, strain, and/or another appropriate type of sensing.

Certain aspects disclosed herein relate to improved wireless charging techniques. Systems, apparatus and methods are disclosed that accommodate free placement of chargeable devices on a surface of a multi-coil wireless charging device. Certain aspects can improve the efficiency and capacity of wireless power transmission to a receiving device. In one example, a wireless charging apparatus has a battery charging power source, a plurality of charging cells configured in a matrix, a first plurality of switches in which each switch is 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 in which each switch is configured to couple a column of coils in the matrix to a second terminal of the battery charging power source. Each charging cell in the plurality of charging cells may include one or more coils surrounding a power transfer area. The plurality of charging cells may be arranged adjacent to a charging surface without overlap of power transfer areas of the charging cells in the plurality of charging cells.

According to certain aspects disclosed herein, power can be wirelessly transferred to a receiving device located anywhere on a charging surface that can have an arbitrarily defined size or shape without regard to any discrete placement locations enabled for charging. Multiple devices can be simultaneously charged on a single charging surface. The charging surface may be manufactured using printed circuit board technology, at low cost and/or with a compact design.

The wireless charging system disclosed in <CIT> needs separate sensing coils and moreover is not accurate in detecting position and movement of the receiving device. In order to overcome such drawbacks, a method and a device are provided according to the independent claims <NUM> and <NUM>, respectively. 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 processing circuit coupled to the free-positioning charging surface can be configured to locate a device to be charged and can select and configure one or more transmitting coils that are optimally positioned to deliver power to the receiving device. Charging cells may be 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, inductive, touch, pressure, load, strain, and/or another appropriate type of sensing.

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 the charging surface. In one example the charging cells are deployed in accordance with a honeycomb packaging configuration. A charging cell may be implemented 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 disclosure, 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 description, a coil in a charging cell may be referred to as a charging coil or a transmitting coil.

In some examples, a charging cell includes coils that are stacked along a common axis. One or more coils may overlap such that they contribute to an induced magnetic field substantially orthogonal to the charging surface. In some examples, a charging cell includes coils that are arranged within a defined portion of the charging surface 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 a dynamically-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 may select some combination of stacks of coils to 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.

<FIG> illustrates an example of a charging cell <NUM> that may be deployed and/or configured to provide a charging surface in a wireless charging device. In this example, the charging cell <NUM> has a substantially hexagonal shape that encloses one or more coils <NUM> constructed using conductors, wires or circuit board traces that can receive a current sufficient to produce an electromagnetic field in a power transfer area <NUM>. In various implementations, some coils <NUM> may have a shape that is substantially polygonal, including the hexagonal charging cell <NUM> illustrated in <FIG>. Other implementations may include or use coils <NUM> that have other shapes. The shape of the coils <NUM> may be determined at least in part by the capabilities or limitations of fabrication technology or to optimize layout of the charging cells on a substrate <NUM> such as a printed circuit board substrate. Each coil <NUM> may be implemented using wires, printed circuit board traces and/or other connectors in a spiral configuration. Each charging cell <NUM> may span two or more layers separated by an insulator or substrate <NUM> such that coils <NUM> in different layers are centered around a common axis <NUM>.

<FIG> illustrates an example of an arrangement <NUM> of charging cells <NUM> provided on a single layer of a segment or portion of a charging surface that may be adapted in accordance with certain aspects disclosed herein. The charging cells <NUM> are arranged according to a honeycomb packaging configuration. In this example, the charging cells <NUM> are 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 cells <NUM> overlap. For example, wires of two or more coils may be interleaved to some extent.

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

<FIG> illustrates the arrangement of power transfer areas provided in a charging surface <NUM> that employs multiple layers of charging cells configured in accordance with certain aspects disclosed herein. The illustrated charging surface is constructed from four layers of charging cells <NUM>, <NUM>, <NUM>, <NUM>. In <FIG>, each power transfer area provided by a charging cell in the first layer of charging cells <NUM> is marked "L1", each power transfer area provided by a charging cell in the second layer of charging cells <NUM> is marked "L2", each power transfer area provided by a charging cell in the third layer of charging cells <NUM> is marked "L3", and each power transfer area provided by a charging cell in the fourth layer of charging cells <NUM> is marked "L4".

<FIG> illustrates an example of a wireless transmitter <NUM> that 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 controller <NUM> may receive a feedback signal filtered or otherwise processed by a filter circuit <NUM>. The controller may control the operation of a driver circuit <NUM> that provides an alternating current to a resonant circuit <NUM>. In some examples, the controller <NUM> may generate a digital frequency reference signal used to control the frequency of the alternating current output by the driver circuit <NUM>. In some instances, the digital frequency reference signal may be generated using a programmable counter or the like. In some examples, the driver circuit <NUM> includes 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 circuit <NUM> or by another circuit. The resonant circuit <NUM> includes a capacitor <NUM> and inductor <NUM>. The inductor <NUM> may represent or include one or more transmitting coils in a charging cell that produced a magnetic flux responsive to the alternating current. The resonant circuit <NUM> may also be referred to herein as a tank circuit, LC tank circuit, or LC tank, and the voltage <NUM> measured at an LC node <NUM> of the resonant circuit <NUM> may be referred to as the tank voltage.

Passive ping techniques may use the voltage and/or current measured or observed at the LC node <NUM> to 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 node <NUM> of the resonant circuit <NUM> or the current in the resonant circuit <NUM>. 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 node <NUM> in the wireless transmitter <NUM> illustrated in <FIG> may be monitored to support passive ping techniques that can detect presence of a chargeable device or other object based on response of the resonant circuit <NUM> to a short burst of energy (the ping) transmitted through the resonant circuit <NUM>.

A passive ping discovery technique may be used to provide fast, low-power discovery. A passive ping may be produced by driving a network that includes the resonant circuit <NUM> with a fast pulse that includes a small amount of energy. The fast pulse excites the resonant circuit <NUM> and causes the network to oscillate at its natural resonant frequency until the injected energy decays and is dissipated. The response of a resonant circuit <NUM> to a fast pulse may be determined in part by the resonant frequency of the resonant LC circuit. A response of the resonant circuit <NUM> to a passive ping that has initial voltage = V<NUM> may be represented by the voltage VLC observed at the LC node <NUM>, such that: <MAT>.

The resonant circuit <NUM> may be monitored when the controller <NUM> or another processor is using digital pings to detect presence of objects. A digital ping is produced by driving the resonant circuit <NUM> for a period of time. The resonant circuit <NUM> is 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 circuit <NUM> by modifying the impedance presented by its power receiving circuit in accordance with signaling state of a modulating signal. The controller <NUM> or other processor then waits for a data modulated response that indicates that a receiving device is nearby.

According to certain aspects disclosed herein, 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, 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 coil or a combination of 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 transmitting coils or one or more predefined charging cells during a charging event.

<FIG> illustrates a first topology <NUM> that 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 cells <NUM> to charge a receiving device. Charging cells <NUM> that are not in use can be disconnected from current flow. A relatively large number of charging cells <NUM> may be used in the honeycomb packaging configuration illustrated in <FIG> and <FIG>, requiring a corresponding number of switches. According to certain aspects disclosed herein, the charging cells <NUM> may be logically arranged in a matrix <NUM> having multiple cells connected to two or more switches that enable specific cells to be powered. In the illustrated topology <NUM>, a two-dimensional matrix <NUM> is provided, where the dimensions may be represented by X and Y coordinates. Each of a first set of switches <NUM> is configured to selectively couple a first terminal of each cell in a column of cells to a first terminal of a voltage or current source <NUM> that provides current to activate coils in one or more charging cells during wireless charging. Each of a second set of switches <NUM> is configured to selectively couple a second terminal of each cell in a row of cells to a second terminal of the voltage or current source <NUM>. A charging cell is active when both terminals of the cell are coupled to the voltage or current source <NUM>.

The use of a matrix <NUM> can 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 matrix <NUM> having N cells can be operated with √N switches. The use of a matrix <NUM> can produce significant cost savings and reduce circuit and/or layout complexity. In one example, a <NUM>-cell implementation can be implemented in a 3x3 matrix <NUM> using <NUM> switches, saving <NUM> switches. In another example, a <NUM>-cell implementation can be implemented in a 4x4 matrix <NUM> using <NUM> switches, saving <NUM> switches.

During operation, at least <NUM> switches are closed to actively couple one coil or charging cell to the voltage or current source <NUM>. Multiple switches can be closed at once in order to facilitate connection of multiple coils or charging cells to the voltage or current source <NUM>. 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> illustrates a second topology <NUM> in which each individual coil or charging cell is directly driven by a driver circuit <NUM> in accordance with certain aspects disclosed herein. The driver circuit <NUM> may be configured to select one or more coils or charging cells <NUM> from a group of coils <NUM> to charge a receiving device. It will be appreciated that the concepts disclosed here in relation to charging cells <NUM> may be applied to selective activation of individual coils or stacks of coils. Charging cells <NUM> that are not in use receive no current flow. A relatively large number of charging cells <NUM> may 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> illustrates certain configurations <NUM>, <NUM>, <NUM>, <NUM> of a charging surface in a wireless charging device upon which a chargeable device <NUM> can be freely positioned. The chargeable device <NUM> has an area that is comparable to the area occupied by each charging cell of a charging surface, or to the area of constituent inductive charging coils in charging cells. In the illustrated example, the chargeable device <NUM> is somewhat larger than a single charging coil <NUM>. Based on the geometry and arrangement of the charging coils <NUM>, <NUM>, <NUM>, <NUM> the chargeable device <NUM> can physically cover adjacent charging coils. In the third and fourth configurations <NUM>, <NUM>, for example, the chargeable device <NUM> has been placed such that it substantially overlaps a single charging coil <NUM> and partially covers multiple other charging coils <NUM>, <NUM>, <NUM>. The chargeable device <NUM> may receive power from one or more charging coils <NUM>, <NUM>, <NUM>, <NUM> after it has established its presence.

Certain aspects of this disclosure can accommodate charging configurations using multiple adjacent charging coils <NUM>, <NUM>, <NUM>, <NUM>. In accordance with certain aspects of this disclosure, any number of charging coils may be available for charging a chargeable device. <FIG> illustrates certain aspects of charging configurations <NUM>, <NUM> that may be defined for a charging surface when a chargeable device <NUM>, <NUM> is presented for charging or is being charged. The number and location of usable charging coils may vary based on the type of an optimally-positioned charging coil <NUM>, <NUM>, the charging contract negotiated between the charging surface and the chargeable device <NUM>, <NUM>, and the topology or configuration of the charging surface. For example, the number and location of usable charging coils may be based on the maximum or contracted charging power transmitted through the active coil <NUM> or potentially through another charging coil <NUM>, or on other factors.

In the first configuration <NUM>, the chargeable device <NUM> may identify coils that are candidates for inclusion in a charging configuration. In the illustrated example, the chargeable device <NUM> has been placed such that its center is substantially coaxial with a first charging coil <NUM>. For the purposes of this description, it will be assumed that the center of a first receiving coil <NUM> within the chargeable device <NUM> is located at the center of the chargeable device <NUM>. In this example, the wireless charging device may determine that the first charging coil <NUM> has the strongest coupling with the receiving coil in the chargeable device <NUM> with respect to the coils in the next bands <NUM>, <NUM> of charging coils. In one example, the wireless charging device may define the charging configuration as including at least the first charging coil <NUM>. In this example, the charging configuration may identify one or more charging coils in the first band <NUM> to be activated during charging procedures.

In the second charging configuration <NUM>, the charging surface may employ sensing techniques that can detect the edges of the chargeable device <NUM>. For example, the outline of the chargeable device <NUM> can be detected using capacitive sense, inductive sense, pressure, Q-factor measurement or any other suitable device locating technology. In some instances, the outline of the chargeable device <NUM> can be determined using one or more sensors provided in or on the charging surface. In the illustrated example, the chargeable device <NUM> has an elongated shape. For the purposes of this description, it will be assumed that the center of a first receiving coil <NUM> within the chargeable device <NUM> is located at the center of the chargeable device <NUM>. The wireless charging device may determine that the first charging coil <NUM> has the strongest coupling with the receiving coil in the chargeable device <NUM>. In one example, the wireless charging device may define the charging configuration as including at least the first charging coil <NUM>. Charging coils <NUM>, <NUM> that are adjacent to the first receiving coil <NUM> and that lie under and within the outline of the chargeable device <NUM> may be included in some charging configurations. Other coils <NUM>, <NUM> that are adjacent to the first receiving coil <NUM> and that lie partially under and within the outline of the chargeable device <NUM> may be defined by some charging configurations to be activated during certain charging procedures.

In some examples, a chargeable device may receive power from two or more active coils. In one example, the chargeable device may have a relatively large footprint with respect to the charging surface and may have multiple receiving coils that can engage multiple charging coils to receive power. In another example, a receiving coil of the chargeable device may be placed substantially equidistant from two or more charging coils and a charging configuration may be defined whereby two or more adjacent charging coils in the charging surface provide power to the chargeable device.

<FIG> illustrates a charging surface <NUM> of a wireless charging device upon which a receiving device <NUM> has been placed. The receiving device <NUM> has a single receiving coil <NUM> that can be electromagnetically coupled with one or more charging cells or transmitting coils (marked LP-<NUM> through LP-<NUM>) in the charging surface <NUM>. In the illustrated example, the receiving coil <NUM> is receiving power from two transmitting coils <NUM>, <NUM>, and one or more drivers may be operated to provide charging currents to the transmitting coils <NUM>, <NUM>.

According to certain aspects of this disclosure, a multi-coil wireless charging system may be adapted or configured to select a configuration of charging coils, which may be referred to herein as a charging configuration. In one example, the charging configuration is selected to yield a maximized efficiency for power transfer to the receiving device <NUM>. In another example, the charging configuration is selected to accommodate the need to charge multiple receiving devices concurrently. A charging configuration may be changed dynamically. For example, a charging configuration may be changed when the receiving device <NUM> is moved with respect to the charging surface <NUM> and/or with respect to the transmitting coils <NUM>, <NUM>. The charging configuration may be changed to maintain or improve charging efficiency, reduce power loss associated with the charging event and/or accommodate charging of a second device placed on the charging surface <NUM>.

Certain aspects disclosed herein relate to apparatus and methods that can detect movement of the receiving device <NUM> with respect to the charging surface <NUM> of a multi-coil free-position charger. Movement detection can include determining the direction of movement <NUM> of the receiving device <NUM>. Movement detection may be implemented to ensure that the electromagnetic flux generated by the charging surface <NUM> can be reconfigured to maintain an uninterrupted flow of power to the receiving device <NUM>.

According to one aspect, movement can be detected by monitoring current or voltage in a tank circuit. In some examples, movement is detected based on changes across a transmitting coil. The voltage across the transmitting coil is dependent on the coupling between the transmitting coil and a receiving coil in a device being charged. The type of change of voltage across the transmitting coil can indicate the nature of the movement of the device being charged. In one example, a voltage drop across the transmitting coil can indicate improved coupling. Improved coupling may result when the center of the receiving coil becomes more closely aligned with the center of the transmitting coil. In another example, a voltage increase across the transmitting coil can indicate decreased coupling. Decreased coupling may result when the center of the receiving coil becomes misaligned with the center of the transmitting coil or the misalignment increases.

In the example illustrated in <FIG>, the LP4 and LP5 transmitting coils <NUM>, <NUM> are actively charging the receiving device <NUM> as the receiving device <NUM> is moving from left to right. According to one aspect of this disclosure, the direction of movement <NUM> of the receiving device <NUM> may be determined by monitoring the voltage across each of three or more transmitting coils adjacent to the receiving device <NUM>. In the illustrated example, the direction of movement may be determined by monitoring the voltage across the active transmitting coils <NUM>, <NUM> and one or more of the transmitting coils in the columns <NUM>, <NUM> adjacent to the active transmitting coils <NUM>, <NUM>. In some examples, the transmitting coils in the columns <NUM>, <NUM> adjacent to the active transmitting coils <NUM>, <NUM> may be continuously powered for measurement purposes. In some examples, the transmitting coils in the columns <NUM>, <NUM> adjacent to the active transmitting coils <NUM>, <NUM> may be continually powered for periodic device detection purposes.

In the illustrated example, the voltage across the active transmitting coils <NUM>, <NUM> may initially decrease as coupling improves with increasing overlap between the active transmitting coils <NUM>, <NUM> and the receiving coil <NUM> in the receiving device <NUM>. The voltage across the active transmitting coils <NUM>, <NUM> may then increase as coupling diminishes with decreasing overlap between the active transmitting coils <NUM>, <NUM> and the receiving coil <NUM> in the receiving device <NUM>. The voltage across a powered transmitting coil in the left adjacent column <NUM> may increase as the receiving device <NUM> moves in the rightward direction of movement <NUM>. The voltage across a powered transmitting coil in the right adjacent column <NUM> may decrease as the receiving device <NUM> moves in the rightward direction of movement <NUM>. In some examples, changes in voltage across a transmitting coil <NUM>, <NUM> may be determined from a time-series of measurements of the voltage.

Voltage measurements obtained from multiple coils can be used to determine the presence of motion and direction of motion of the receiving device <NUM>. Table <NUM> illustrates the effect on measured voltages at the point in time illustrated in the example in <FIG>. In some implementations, phase and current may be used to determine presence of motion and direction of motion of the receiving device <NUM>.

In some conventional wireless charging systems, voltage on the coils is often monitored for a variety of reasons, including for over-voltage protection of components. Such systems may be adapted to provide for motion detection and direction of motion detection in accordance with certain aspects of the disclosure.

<FIG> is flowchart <NUM> illustrating a first example of a method for operating a wireless charging device that includes or implements a charging surface. The method may be performed by a controller provided in the wireless charging apparatus. At block <NUM>, the controller may provide a charging current to at least one active charging coil in the charging surface. The charging current may be configured to cause a transfer of power through the at least one active charging coil to a chargeable device located on the charging surface. At block <NUM>, the controller may measure voltages across three or more charging coils in the charging surface. At block <NUM>, the controller may determine that the chargeable device is in motion across the charging surface based on changes in the voltages measured across the three or more charging coils.

In various implementations, the controller may determine a direction of motion of the chargeable device across the charging surface based on the changes in the voltages measured across the three or more charging coils. The controller may determine that the chargeable device is moving away from a first active charging coil when the voltage measured across the first active charging coil is increasing. The controller may determine that the chargeable device is moving toward an adjacent charging coil when the voltage measured across the adjacent charging coil is increasing. The controller may determine a direction of motion that indicates that the chargeable device is moving away from a first active charging coil and toward an adjacent charging coil when the voltage measured across the first active charging coil is increasing and the voltage measured across the adjacent charging coil is increasing and may redirect the charging current from the first active charging coil to the adjacent charging coil based on the determined direction of motion.

A controller provided in a wireless charging apparatus that has been adapted in accordance with certain aspects of this disclosure can rapidly determine motion of the receiving device <NUM> and can rapidly characterize the nature of detected motion using rates of change in voltage or current measurements. Motion and nature of motion may be determined from signals provided by one or more sensors and/or from voltage, phase and current measurements obtained from one or more coils of a charging circuit. In one example, the voltage <NUM> measured at the LC node <NUM> of the resonant circuit <NUM> illustrated in <FIG> can be used to determine the presence of motion and direction of motion of the receiving device <NUM>. In some examples, filter circuits may be used to indicate the rate of change of a voltage.

<FIG> illustrates an example of a filter <NUM> that produces a signal <NUM> from which motion information can be extracted in accordance with certain aspects of this disclosure. The filter <NUM> may be an exponential filter, or other low-pass filter. In one example, the filter <NUM> may correspond to the filter circuit <NUM> in <FIG>. In this example, the filter <NUM> produces an output signal <NUM> that has a voltage level defined by the function f(x) defined as: <MAT> where x is the voltage level of the input signal <NUM> provided to the filter <NUM>. The graph <NUM> illustrates the response of the filter <NUM> to an input signal <NUM> that includes step changes. In the illustrated example, the voltage of the input signal <NUM> increases as the receiving device <NUM> approaches the monitored coil or sensor, and the voltage of the input signal <NUM> decreases as the receiving device <NUM> recedes (moves away) from the monitored coil or sensor. The output of the filter <NUM> follows the input signal <NUM>, transitioning exponentially toward the voltage level at which the input signal <NUM> settles.

As illustrated by the graph <NUM>, the derivative of the curve segments <NUM>, <NUM>, <NUM>, <NUM> indicate whether the receiving device <NUM> is in motion and the direction of any motion. The derivative, which may be representative of the gradient or rate of change of the voltage at voltage level x, may be represented as: <MAT>.

In some implementations, the controller may determine motion and direction of motion by distinguishing between three types of derivative, as illustrated in Table <NUM>.

The value of the derivative may indicate approaching motion, receding motion and no motion (stationary). In some implementations, one or more circuits may be configured to generate f'(x) as an output that can be provided to comparison circuits. The comparison circuits may be configured to generate events and other information used by the controller to manage charging configurations. In some instances, the filter <NUM> may itself provide f'(x) as an output in addition to f(x).

Measurements received from multiple sensors and/or voltage measurements obtained from multiple coils can be used to determine a motion vector of the receiving device <NUM>, where the motion vector identifies a direction of motion in two or three dimensional space. For example, each of the voltage signals associated with the <NUM> coils listed in Table <NUM> may be provided to a corresponding low-pass filter such as the filter <NUM>. The derivative of the output signal may be used to determine whether the receiving device <NUM> is approaching or receding from the coil. In some instances, the rate of increase or decrease of the voltage levels may be used to produce a motion vector. The motion vector may be used to select or change charging configurations to match the movement of the receiving device <NUM>.

<FIG> is flowchart <NUM> illustrating a second example of a method for operating a wireless charging device that includes or implements a charging surface. The method may be performed by a controller provided in the wireless charging apparatus. At block <NUM>, the controller may determine that a chargeable device is in motion across the charging surface based on a change in a signal received from a sensor or representative of the voltage measured at or across a transmitting coil. At block <NUM>, the controller may determine a rate of change of the signal. At block <NUM>, the controller may determine a direction of motion of the chargeable device based on a comparison of the rate of change to a threshold value.

In some implementations, the chargeable device is approaching the sensor or the transmitting coil when the threshold value exceeds the rate of change, and/or the chargeable device is receding from the sensor or the transmitting coil when the rate of change exceeds the threshold value. The chargeable device may be stationary with respect to the sensor or the transmitting coil when rate of change is substantially equal to the threshold value. In one example, the rate of change may be considered substantially equal to the threshold value when the rate of change and the threshold value differ by less than <NUM>% of the threshold value. In another example, the rate of change may be considered substantially equal to the threshold value when the rate of change and the threshold value differ by less than <NUM>% of the threshold value.

In certain implementations, the controller may determine a rate of change of each of a plurality of signals. Each of the plurality of signals may be provided by an associated sensor or the transmitting coil. The controller may determine direction of motion of the chargeable device in two-dimensional space based on a comparison of the rates of change of the plurality of signals to the threshold value. The controller may determine direction of motion of the chargeable device in three-dimensional space based on the comparison of the rates of change of the plurality of signals to the threshold value.

In some implementations, the controller may determine a charging configuration based on the direction of motion of the chargeable device and may provide a charging current to at least one active transmitting coil in the charging surface identified in the charging configuration. The charging current may be configured to cause a transfer of power through the at least one active transmitting coil to the chargeable device.

<FIG> illustrates an example of a hardware implementation for an apparatus <NUM> that may be incorporated in a wireless charging device or in a receiving device that enables a battery to be wirelessly charged. In some examples, the apparatus <NUM> may 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 circuit <NUM>. The processing circuit <NUM> may include one or more processors <NUM> that are controlled by some combination of hardware and software modules. Examples of processors <NUM> include 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 processors <NUM> may include specialized processors that perform specific functions, and that may be configured, augmented or controlled by one of the software modules <NUM>. The one or more processors <NUM> may be configured through a combination of software modules <NUM> loaded during initialization, and further configured by loading or unloading one or more software modules <NUM> during operation.

In the illustrated example, the processing circuit <NUM> may be implemented with a bus architecture, represented generally by the bus <NUM>. The bus <NUM> may include any number of interconnecting buses and bridges depending on the specific application of the processing circuit <NUM> and the overall design constraints. The bus <NUM> links together various circuits including the one or more processors <NUM>, and storage <NUM>. Storage <NUM> may include memory devices and mass storage devices and may be referred to herein as computer-readable media and/or processor-readable media. The storage <NUM> may include transitory storage media and/or non-transitory storage media.

The bus <NUM> may also link various other circuits such as timing sources, timers, peripherals, voltage regulators, and power management circuits. A bus interface <NUM> may provide an interface between the bus <NUM> and one or more transceivers <NUM>. In one example, a transceiver <NUM> may be provided to enable the apparatus <NUM> to communicate with a charging or receiving device in accordance with a standardsdefined protocol. Depending upon the nature of the apparatus <NUM>, a user interface <NUM> (e.g., keypad, display, speaker, microphone, joystick) may also be provided, and may be communicatively coupled to the bus <NUM> directly or through the bus interface <NUM>.

One or more processors <NUM> in the processing circuit <NUM> 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, algorithms, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside in computer-readable form in the storage <NUM> or in an external computer-readable medium. The external computer-readable medium and/or storage <NUM> may include a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., a compact disc (CD) or a digital versatile disc (DVD)), a smart card, a flash memory device (e.g., a "flash drive," a card, a stick, or a key drive), RAM, ROM, a programmable read-only memory (PROM), an erasable PROM (EPROM) including EEPROM, a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium and/or storage <NUM> may also include, by way of example, a carrier wave, a transmission line, and any other suitable medium for transmitting software and/or instructions that may be accessed and read by a computer. Computer-readable medium and/or the storage <NUM> may reside in the processing circuit <NUM>, in the processor <NUM>, external to the processing circuit <NUM>, or be distributed across multiple entities including the processing circuit <NUM>. The computer-readable medium and/or storage <NUM> 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.

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

Some of the software modules <NUM> may be loaded during initialization of the processing circuit <NUM>, and these software modules <NUM> may configure the processing circuit <NUM> to enable performance of the various functions disclosed herein. For example, some software modules <NUM> may configure internal devices and/or logic circuits <NUM> of the processor <NUM>, and may manage access to external devices such as a transceiver <NUM>, the bus interface <NUM>, the user interface <NUM>, timers, mathematical coprocessors, and so on. The software modules <NUM> may 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 circuit <NUM>. The resources may include memory, processing time, access to a transceiver <NUM>, the user interface <NUM>, and so on.

In one implementation, the apparatus <NUM> includes or operates as a wireless charging apparatus 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 processors <NUM>. 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.

The controller may be configured to provide a charging current to at least one active transmitting coil in the charging surface, measure voltages across three or more transmitting coils in the charging surface and determine that the chargeable device is in motion across the charging surface based on changes in the voltages measured across the three or more transmitting coils. The charging current causes a transfer of power through the at least one active transmitting coil to a chargeable device located on the charging surface.

In various implementations, the controller may determine a direction of motion of the chargeable device across the charging surface based on the changes in the voltages measured across the three or more transmitting coils. The controller may determine that the chargeable device is moving away from a first active transmitting coil when the voltage measured across the first active transmitting coil is increasing. The controller may determine that the chargeable device is moving toward an adjacent transmitting coil when the voltage measured across the adjacent transmitting coil is increasing. The controller may determine a direction of motion that indicates that the chargeable device is moving away from a first active transmitting coil and toward an adjacent transmitting coil when the voltage measured across the first active transmitting coil is increasing and the voltage measured across the adjacent transmitting coil is increasing, and may redirect the charging current from the first active transmitting coil to the adjacent transmitting coil based on the determined direction of motion.

In another implementation, the apparatus <NUM> includes or operates as a wireless charging apparatus 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 processors <NUM>. 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.

The controller may be configured to determine that a chargeable device is in motion across the charging surface based on a change in a signal received from a sensor or representative of the voltage measured at or across a transmitting coil, determine a rate of change of the signal, and determine a direction of motion of the chargeable device based on a comparison of the rate of change to a threshold value.

In some examples, the chargeable device is approaching the sensor or the transmitting coil when the threshold value exceeds the rate of change. The chargeable device may be receding from the sensor or the transmitting coil when the rate of change exceeds the threshold value. The chargeable device may be stationary with respect to the sensor or the transmitting coil when rate of change is substantially equal to the threshold value. The rate of change may be considered substantially equal to the threshold value when the rate of change and the threshold value differ by, for example, less than <NUM>% or less than <NUM>% of the threshold value.

In some implementations, the controller may determine a charging configuration based on the direction of motion of the chargeable device, and may provide a charging current to at least one active transmitting coil in the charging surface identified in the charging configuration. The charging current may be configured to cause a transfer of power through the at least one active transmitting coil to the chargeable device.

In some implementations, the storage <NUM> maintains instructions and information where the instructions are configured to cause the one or more processors <NUM> to provide a charging current to at least one active transmitting coil in the charging surface, measure voltages across three or more transmitting coils in the charging surface, and determine that the chargeable device is in motion across the charging surface based on changes in the voltages measured across the three or more transmitting coils. The charging current may be configured to cause a transfer of power through the at least one active transmitting coil to a chargeable device located on the charging surface.

In some implementations, the instructions are configured to cause the one or more processors <NUM> to determine a direction of motion of the chargeable device across the charging surface based on the changes in the voltages measured across the three or more transmitting coils. The one or more processors <NUM> may determine that the chargeable device is moving away from a first active transmitting coil when the voltage measured across the first active transmitting coil is increasing. The one or more processors <NUM> may determine that the chargeable device is moving toward an adjacent transmitting coil when the voltage measured across the adjacent transmitting coil is increasing. The one or more processors <NUM> may determine a direction of motion that indicates that the chargeable device is moving away from a first active transmitting coil and toward an adjacent transmitting coil when the voltage measured across the first active transmitting coil is increasing and the voltage measured across the adjacent transmitting coil is increasing, and may redirect the charging current from the first active transmitting coil to the adjacent transmitting coil based on the determined direction of motion.

In certain examples, the instructions are configured to cause the one or more processors <NUM> to configure the plurality of transmitting coils based on a current charging configuration and receive a reported power from the chargeable device while the chargeable device is being charged using the current charging configuration. The instructions may be configured to cause the one or more processors <NUM> to calculate power loss as a difference between the reported power and power expended by the wireless charging device while charging the chargeable device. The instructions may be configured to cause the one or more processors <NUM> to select a charging configuration after detecting that the chargeable device is located on the charging surface. The instructions may be configured to cause the one or more processors <NUM> to select a charging configuration after detecting that the chargeable device has been relocated on the charging surface.

In some implementations, the instructions are configured to cause the one or more processors <NUM> to determine that a chargeable device is in motion across the charging surface based on a change in a signal received from a sensor or representative of the voltage measured at or across a transmitting coil, determine a rate of change of the signal, and determine a direction of motion of the chargeable device based on a comparison of the rate of change to a threshold value.

In some implementations, the chargeable device is approaching the sensor or the transmitting coil when the threshold value exceeds the rate of change, and/or the chargeable device is receding from the sensor or the transmitting coil when the rate of change exceeds the threshold value. The chargeable device may be stationary with respect to the sensor or the transmitting coil when rate of change is substantially equal to the threshold value. The rate of change may be considered substantially equal to the threshold value when the rate of change and the threshold value differ by less than <NUM>% of the threshold value.

In certain implementations, the instructions are configured to cause the one or more processors <NUM> to determine a rate of change of each of a plurality of signals. Each of the plurality of signals may be provided by an associated sensor or the transmitting coil. The one or more processors <NUM> may determine direction of motion of the chargeable device in two-dimensional space based on a comparison of the rates of change of the plurality of signals to the threshold value. The one or more processors <NUM> may determine direction of motion of the chargeable device in three-dimensional space based on the comparison of the rates of change of the plurality of signals to the threshold value.

In some implementations, the instructions are configured to cause the one or more processors <NUM> to determine a charging configuration based on the direction of motion of the chargeable device, and to provide a charging current to at least one active transmitting coil in the charging surface identified in the charging configuration. The charging current may be configured to cause a transfer of power through the at least one active transmitting coil to the chargeable device.

Claim 1:
A method for operating a charging surface (<NUM>) in a wireless charging device, comprising:
providing a charging current to at least one active transmitting coil (LP-i) in a plurality of transmitting coils (LP-<NUM> - LP-<NUM>) that is deployed across the charging surface, wherein the charging current causes a wireless transfer of power through the at least one active transmitting coil (<NUM>, <NUM>) to a chargeable device (<NUM>) located on the charging surface and wherein each of the plurality of transmitting coils is configured to wirelessly transmit power through the charging surface when activated by an alternating current; the method being characterized by the following steps:
measuring voltages across three or more transmitting coils in the charging surface; and
determining that the chargeable device is in motion across the charging surface based on changes in the voltages measured across the three or more transmitting coils;
determining a rate of change of a signal representative of the voltage measured across a first transmitting coil in the three or more transmitting coils; and determining a direction of motion of the chargeable device across the charging surface based on a comparison of the rate of change of the signal with a threshold value.