Object detection for wireless power transmission

Abstract

To provide object detection for wireless power transfer.SOLUTION: A wireless power transmitter (WPT) may include a WPT circuit including a radio WPT coil which transmits a wireless power signal, and a control circuit which is connected to the WPT circuit. While the WPT is connected to a wireless power receiver, the control circuit measures a current value of a first function of a quality coefficient and a resonant frequency of the wireless power transmitter coil and a current value of a second function of a quality coefficient and a resonant frequency of the WPT coil, determines a change between the measured current values of the first function and the second function of the quality coefficient and the resonant frequency of the WPT coil and corresponding baseline values, and determines whether a foreign substance is present in accordance with the change, exceeding a threshold value in a magnetic state space, between the measured current values of the first function and the second function of the quality coefficient and the resonant frequency and the corresponding baseline values.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority to U.S. Provisional Application No. 63 / 581318, “Mated-Q Object Detection for High Power Wireless Power Transfer,” filed on 8 September 2023; U.S. Provisional Application No. 63 / 605047, “Object Detection for Wireless Power Transfer,” filed on 1 December 2023; U.S. Patent Application No. 18 / 612886, “Mated-Q Object Detection for High Power Wireless Power Transfer,” filed on 21 March 2024; U.S. Patent Application No. 18 / 612892, “Object Detection for Wireless Power Transfer,” filed on 21 March 2024; and U.S. Patent Application No. 18 / 612904, “Object Detection for Wireless Power Transfer,” filed on 21 March 2024, each of which is incorporated herein by reference in its entirety. [Background technology]

[0002] Electronic devices such as smartphones, tablet computers, smartwatches, wireless earphones, and styluses may employ wireless power transmission to facilitate charging of their internal batteries. As a result, it may be desirable to provide an increased level of power transmission. However, such higher power levels may affect wireless power transmission or necessitate improved detection of other objects that could be affected by wireless power transmission. [Overview of the Initiative]

[0003] A wireless power transmitter may include a wireless power transmitting circuit having a wireless power transmitting coil for transmitting wireless power signals, and a control circuit coupled to the wireless power transmitting circuit. The control circuit measures the current values ​​of a first function of the quality coefficient and resonant frequency of the wireless power transmitting coil, and a second function of the quality coefficient and resonant frequency of the wireless power transmitting coil, while the wireless power transmitter is coupled to a wireless power receiver. It determines the change between the measured current values ​​of the first and second functions of the quality coefficient and resonant frequency of the wireless power transmitting coil and the corresponding baseline values, and determines whether foreign matter is present based on the change between the measured current values ​​of the first and second functions of the quality coefficient and resonant frequency and the corresponding baseline values ​​that exceed a threshold in magnetic state space. The first function of the quality coefficient and resonant frequency may be the quality coefficient. The second function of the quality coefficient and resonant frequency may be the resonant frequency. The threshold may include a plurality of linear thresholds.

[0004] A wireless power transmitter may include a wireless power transmitting circuit having a wireless power transmitting coil for transmitting wireless power signals, and a control circuit coupled to the wireless power transmitting circuit, the control circuit measuring the current values ​​of a first function of the quality coefficient, resonant frequency, and coupling coefficient of the wireless power transmitting coil, the current values ​​of a second function of the quality coefficient, resonant frequency, and coupling coefficient of the wireless power transmitting coil, and the current values ​​of a third function of the quality coefficient, resonant frequency, and coupling coefficient of the wireless power transmitting coil while the wireless power transmitter is coupled to a wireless power receiver, determining the distance between the measured current values ​​of the first, second, and third functions of the quality coefficient, resonant frequency, and coupling coefficient of the wireless power transmitting coil and the curve fit to the corresponding baseline values, and determining whether foreign matter is present depending on the distance between the measured current values ​​of the first, second, and third functions of the quality coefficient, resonant frequency, and coupling coefficient and the curve fit to the corresponding baseline values ​​in magnetic state space that are above a threshold or between a plurality of thresholds.

[0005] The first, second, and third functions of the quality factor, resonant frequency, and coupling coefficient may be selected to provide a linear curve fit in magnetic state space. The first function of the quality factor, resonant frequency, and coupling coefficient may be the square of the coupling coefficient. The second function of the quality factor, resonant frequency, and coupling coefficient may be the square of the resonant frequency, and the third function of the quality factor, resonant frequency, and coupling coefficient may be the reciprocal of the product of the resonant frequency and the quality factor. The distance may be the L1 distance or the L2 distance (or any other suitable distance).

[0006] The control circuit can suppress wireless power transmission in response to the detection of foreign objects. The control circuit can transmit power at a level below the maximum power level in response to the detection of foreign objects.

[0007] The control circuit may measure the current quality factor and resonant frequency of a radio power transmitting coil by: causing an inverter to supply one or more signal pulses to the radio power transmitting coil; measuring the response to the supplied one or more signal pulses, the response comprising a ringing signal having an attenuated envelope characterized by the frequency of the ringing signal and the current quality factor; and determining the current quality factor and resonant frequency from the frequency of the ringing signal.

[0008] The control circuit can characterize an object as moderate or strong impurity based on the distance between the measured current values ​​of the quality coefficient, resonant frequency, and first, second, and third functions of the coupling coefficient of the wireless power transmitting coil and the curve fitting to the corresponding baseline value. Depending on whether the control circuit determines that the object is strong impurity, it can suppress wireless power transmission. Alternatively, depending on whether the control circuit determines that the object is moderate impurity, it can enable wireless power transmission at a relatively lower power level.

[0009] The corresponding baseline value may be measured during the manufacture of the radio power transmitter. The corresponding baseline value may be updated during the field operation of the radio power transmitter. The control circuit can determine the distance between the measured current values ​​of the first, second, and third functions of the quality coefficient, resonant frequency, and coupling coefficient of the radio power transmitting coil, using a scale factor based on a specific transmitter-receiver pairing.

[0010] A method for operating a wireless power transmitter, which includes a wireless power transmitting circuit including a wireless power transmitting coil configured to transmit a wireless power signal, and a control circuit coupled to the wireless power transmitting circuit, can be performed by the wireless power control circuit and includes measuring the current value of a first function of the quality coefficient and resonant frequency of the wireless power transmitting coil and the current value of a second function of the quality coefficient and resonant frequency of the wireless power transmitting coil while the wireless power transmitter is coupled to a wireless power receiver; comparing the measured current values ​​of the first and second functions of the quality coefficient and resonant frequency of the wireless power transmitting coil with corresponding baseline values; and detecting foreign matter, at least in part, based on the comparison of the measured current values ​​of the first and second functions of the quality coefficient and resonant frequency with corresponding baseline values.

[0011] A first function of the quality factor and the resonant frequency may be the quality factor. A second function of the quality factor and the resonant frequency may be the resonant frequency. Comparison of the measured current values ​​of the first and second functions of the quality factor and the resonant frequency with the corresponding baseline values ​​may include determining whether the difference between the measured current values ​​and the corresponding baseline values ​​exceeds a threshold including a plurality of linear thresholds.

[0012] A method for operating a wireless power transmitter, comprising a wireless power transmitting circuit including a wireless power transmitting coil configured to transmit wireless power signals, and a control circuit coupled to the wireless power transmitting circuit, can be performed by the wireless power control circuit, which measures, while the wireless power transmitter is coupled to a wireless power receiver, the current value of a first function of the quality coefficient, resonant frequency, and coupling coefficient of the wireless power transmitting coil, the current value of a second function of the quality coefficient, resonant frequency, and coupling coefficient of the wireless power transmitting coil, and the current value of a third function of the quality coefficient, resonant frequency, and coupling coefficient of the wireless power transmitting coil, and the quality coefficient of the wireless power transmitting coil, resonant frequency, The method includes comparing the measured current values ​​of the quality coefficient, resonant frequency, and coupling coefficient of a radio power transmitting coil with the corresponding baseline values ​​by determining the distance between the measured current values ​​of the first, second, and third functions of the quality coefficient, resonant frequency, and coupling coefficient and the curve fitting to the corresponding baseline values ​​in magnetic state space, and detecting foreign objects based at least in part on the distance between the measured current values ​​of the quality coefficient, resonant frequency, and coupling coefficient and the curve fitting to the corresponding baseline values ​​in magnetic state space that exceed a threshold.

[0013] The first, second, and third functions of the quality factor, resonant frequency, and coupling coefficient may be selected to provide a linear curve fit in magnetic state space. The first function of the quality factor, resonant frequency, and coupling coefficient may be the square of the coupling coefficient. The second function of the quality factor, resonant frequency, and coupling coefficient may be the square of the resonant frequency. The third function of the quality factor, resonant frequency, and coupling coefficient may be the reciprocal of the product of the resonant frequency and the quality factor. The distance may be the L1 distance or the L2 distance (or any other suitable distance).

[0014] Measuring the current quality factor and resonant frequency of a wireless power transmission may involve causing an inverter to supply one or more signal pulses to a wireless power transmitter coil, measuring the response to the supplied one or more signal pulses, the response comprising a ringing signal having an attenuation envelope characterized by the frequency of the ringing signal and the current quality factor, and determining the current quality factor from the frequency of the ringing signal.

[0015] The method may further include suppressing wireless power transmission in response to the detection of a foreign object. The method may further include transmitting power at a level below the maximum power level in response to the detection of a foreign object.

[0016] The method may further include characterizing the foreign object as a moderate or strong foreign object based on the distance between the measured current value and the curve fitting to the corresponding baseline value in the magnetic state space. Depending on whether the foreign object is determined to be a strong foreign object, the method may further include suppressing wireless power transmission. Alternatively, depending on whether the foreign object is determined to be a moderate foreign object, the method may include enabling wireless power transmission at a relatively lower power level.

[0017] The corresponding baseline value may be measured during the manufacture of the radio power transmitter. The corresponding baseline value may be updated during the field operation of the radio power transmitter. The method may further include scaling the corresponding baseline value using a scaling factor based on a particular transmitter-receiver pairing. [Brief explanation of the drawing]

[0018] [Figure 1] A block diagram of the wireless power transmission system is shown.

[0019] [Figure 2] A simplified schematic diagram of a wireless power transmission system is shown.

[0020] [Figure 3] This graph shows the impulse response of a wireless power transmitting coil, which can be analyzed to measure the coil's quality coefficient value.

[0021] [Figure 4] This is a simplified schematic diagram of a wireless power transmitter showing a circuit that may be used to perform quality factor measurement.

[0022] [Figure 5] The following formulas can be used to determine parameters such as the coil quality factor based on impedance measurements.

[0023] [Figure 6] This is a formula showing the compensation factor that can be applied to the current quality factor measurement to determine the compensated quality factor value.

[0024] [Figure 7] This figure illustrates an example of foreign object detection operation based on a measured quality factor in a wireless power transmission system. [Figure 8] This figure illustrates an example of foreign object detection operation based on a measured quality factor in a wireless power transmission system.

[0025] [Figure 9] This paper describes the principle of foreign object detection using combined Q and resonant frequency measurements.

[0026] [Figure 10] A flowchart of the combination Q foreign object detection method is shown.

[0027] [Figure 11] This shows the sequence of combined Q measurements in a situation where an object is being carried near a combined wireless power transmitter / receiver pair.

[0028] [Figure 12] A flowchart illustrating the parameter scaling operation of wireless power transmission devices is shown. [Figure 13] A flowchart illustrating the parameter scaling operation of wireless power transmission devices is shown.

[0029] [Figure 14] This document describes the process for scaling the combined Q and resonant frequency parameters.

[0030] [Figure 15] This shows the variable threshold for detecting foreign objects in combination Q.

[0031] [Figure 16A] This paper presents a multidimensional combinatorial Q-state space for deriving a linear threshold line for foreign object detection. [Figure 16B] This paper presents a multidimensional combinatorial Q-state space for deriving a linear threshold line for foreign object detection.

[0032] [Figure 17A] This document presents an alternative distance metric for multidimensional combination Q-type foreign object detection. [Figure 17B] This document presents an alternative distance metric for multidimensional combination Q-type foreign object detection. [Figure 17C] This document presents an alternative distance metric for multidimensional combination Q-type foreign object detection. [Figure 17D] This document presents an alternative distance metric for multidimensional combination Q-type foreign object detection.

[0033] [Figure 18A] This demonstrates ecosystem scaling of a multidimensional combinatorial Q-type foreign object detection system. [Figure 18B] This demonstrates ecosystem scaling of a multidimensional combinatorial Q-type foreign object detection system. [Figure 18C] This demonstrates ecosystem scaling of a multidimensional combinatorial Q-type foreign object detection system.

[0034] [Figure 19] This demonstrates the determination of the distance to a foreign object in a multidimensional combined Q-type foreign object detection system.

[0035] [Figure 20] This demonstrates limiting the transmission power based on the distance to the foreign object in a multidimensional combined Q foreign object detection system.

[0036] [Figure 21] This paper describes the principle of case detection using combined Q and resonant frequency measurements. [Modes for carrying out the invention]

[0037] For the sake of clarity and to enhance understanding of the disclosed concepts, the following description includes numerous specific details. As part of this description, some of the drawings in this disclosure represent structures and devices in block diagram format for simplification. For clarity, not all features of actual implementations are described herein. Furthermore, the language used herein has been selected solely for readability and explanatory purposes, and not to limit or restrict the disclosed subject matter. Rather, the appended claims are intended for this purpose.

[0038] Various embodiments of the disclosed concepts are shown in the accompanying drawings as examples, not as limitations, and similar reference numbers indicate similar elements. For the sake of illustration simplification and clarity, where appropriate, reference numbers are repeated in different drawings to indicate corresponding and / or similar elements. In addition, numerous specific details are provided to provide a complete understanding of the implementations described herein. In other examples, methods, procedures, and components are not described in detail so as not to obscure the related functions described. References to “an,” “one,” or “another” embodiments in this disclosure do not necessarily refer to the same or different embodiments, but mean at least one. Given drawings are used to illustrate multiple embodiments or species of this disclosure, and not all elements in the drawings may be required in a given embodiment or species. Reference numbers, where provided in a given drawing, refer to the same element across several drawings, but are not repeated in all drawings. Drawings are not to scale unless otherwise indicated, and proportions of certain parts may be exaggerated to better illustrate the details and features of this disclosure.

[0039] A wireless power system may include a wireless power transmitting device such as a wireless charging pack or mat. The wireless power transmitting device can wirelessly transmit power to a wireless power receiving device. The wireless power receiving device may be a device such as a wristwatch, mobile phone, tablet computer, laptop computer, or other electronic device. The wireless power receiving device can use power from the wireless power transmitting device to power the device and / or charge its internal battery. Wireless power may be transmitted from the wireless power transmitting device to the wireless power receiving device using one or more wireless power transmitting coils. The wireless power receiving device may have one or more wireless power receiving coils coupled to a rectifier circuit that can convert the received wireless power signal into DC power.

[0040] If foreign objects such as clips, coins, or other metallic objects are present near the radio power transmitting coil of a radio power transmitting device, eddy currents may be generated in the foreign objects, potentially causing their temperature to rise. To determine whether such foreign objects are present near a radio power transmitting device, the radio power transmitting device may measure the quality factor (also known as the "Q factor" or "Q") of the radio power transmitting coil and determine whether the quality factor has been affected by the presence of the foreign object. In some cases, the Q factor can be measured in "open air," meaning the transmitter is not coupled to the receiver. In other cases, as will be described in more detail below, the Q factor can be measured as "combined," meaning the transmitter is coupled to the receiver device. In either / both cases, detecting the presence of foreign objects can allow appropriate action to be taken (for example, the radio power transmitting device may cease radio power transmission operation or reduce the power level transmitted whenever foreign objects are detected).

[0041] An exemplary wireless power system (wireless charging system) is shown in Figure 1. The wireless power system 8 may include a wireless power transmitter 12 and a wireless power receiver 24. The wireless power transmitter 12 may include a control circuit 16. The wireless power receiver 24 may include a control circuit 30. Each control circuit may be used to control the operation of the wireless power system 8. This control circuit may include processing circuits associated with application-specific integrated circuits having a microprocessor, power management unit, baseband processor, digital signal processor, microcontroller, and / or processing circuits. The processing circuits can implement desired control and communication functions in the wireless power transmitter 12 and the wireless power receiver 24. For example, the processing circuits may be used for coil selection, determining power transmission levels, processing sensor data and other data for detecting foreign objects and performing other tasks, processing user input, handling negotiations between the wireless power transmitter 12 and the wireless power receiver 24, transmitting and receiving in-band and out-of-band data, performing measurements, and otherwise controlling the operation of the wireless power system 8.

[0042] The control circuits 16 and 30 within System 8 may be configured to perform operations using hardware (e.g., dedicated hardware or circuitry), firmware, and / or software. Software code for performing operations within System 8 may be stored on a non-temporary computer-readable storage medium (e.g., a tangible computer-readable storage medium) within the control circuits. Software code may be referred to as software, data, program instructions, instructions, and / or code. The non-temporary computer-readable storage medium may include non-volatile memory such as Non-Volatile Random-Access Memory (NVRAM), one or more hard drives (e.g., magnetic drives or solid-state drives), one or more removable flash drives, or other removable media. Software stored on the non-temporary computer-readable storage medium can be executed on the processing circuits of control circuits 16 and / or 30. The processing circuits may include application-specific integrated circuits having processing circuits, one or more microprocessors, a Central Processing Unit (CPU), or other processing circuits including analog, digital, and / or hybrid circuits.

[0043] The wireless power transmitter 12 may be a standalone power adapter (e.g., a wireless charging mat or charging pack including a power adapter circuit), a wireless charging mat or pack coupled to a power adapter or other device by a cable, a portable device, a device incorporated into furniture, a vehicle, or other system, a removable battery case, or other wireless power transmission equipment. An exemplary configuration in which the wireless power transmitter 12 is a wireless charging mat is sometimes described herein as an example.

[0044] The wireless power receiver 24 may be a portable electronic device such as a wristwatch, mobile phone, laptop computer, tablet computer, earphones, stylus or other accessories, or other electronic device. The wireless power transmitter 12 may be connected to a wall outlet (e.g., an AC power source), may have a battery for power supply, and / or may have another power source. The wireless power transmitter 12 may have an AC-DC power converter, such as an AC-DC power converter 14, for converting alternating current (AC) power from the wall outlet or other power source to direct current (DC) power. DC power can be used to power the control circuit 16. During operation, a controller in the control circuit 16 may transmit wireless power to the power receiving circuit 54 of the wireless power receiver 24 using a power transmitting circuit 52. The power transmitting circuit 52 may have a switching circuit (e.g., an inverter circuit 61 formed from transistors) that is turned on and off based on a control signal provided by the control circuit 16 to generate an AC current signal via one or more wireless power transmitting coils, such as one or more wireless power transmitting coils 36. These coil drive signals cause one or more coils 36 to transmit wireless power. The multiple coils 36 may be arranged in a planar coil array (for example, in a configuration where device 12 is a wireless charging mat) or they may be arranged to form a cluster of coils (for example, in a configuration where device 12 is a wireless charging pack). In some configurations, the wireless power transmitter 12 (e.g., a charging mat, pack, etc.) may have only a single coil. In other configurations, the wireless power transmitter may have multiple coils.

[0045] When an AC current flows through one or more coils 36, an AC electromagnetic field (e.g., a magnetic field) (radio power signal 44) is generated, which is received by one or more corresponding receiving coils, such as one or more coils 48 in the radio power receiver 24. The radio power receiver 24 may have a single coil 48 or any other appropriate number of coils 48. When the AC electromagnetic field is received by one or more coils 48, a corresponding AC current is induced in the coils 48. The AC signal used when transmitting radio power may have any appropriate frequency (e.g., 100-250 kHz, 128 kHz, 326 kHz, 360 kHz, 300-400 kHz, 1.7-1.8 MHz, 6.78 MHz, etc.). A rectifier circuit, such as a rectifier circuit 50, which includes rectifier components such as synchronous rectified metal oxide semiconductor transistors arranged in a bridge network, converts the received AC signal (the received AC signal associated with the electromagnetic signal 44) into a DC voltage signal for supplying power from one or more coils 48 to the radio power receiver 24.

[0046] DC voltage (rectifier output voltage V) generated by the rectifier circuit 50 rectThe (sometimes referred to as) can be used to charge batteries such as battery 58 and to supply power to other components in the wireless power receiver 24. For example, the wireless power receiver 24 may include an input / output device 56. The input / output device 56 may include an input device for collecting user input and / or performing environmental measurements, and may include an output device for providing output to the user. For example, the input / output device 56 may include a display that produces a visual output, a speaker that provides output as an audio signal, a light-emitting diode status indicator light and other light-emitting components that provide status information and / or other information to the user, a tactile device that produces vibration and other tactile output, and / or other output devices. The input / output device 56 may also include sensors for collecting user input and / or performing measurements around the wireless power system 8.Exceptional sensors that may be included in the input / output device 56 include three-dimensional sensors (e.g., three-dimensional image sensors such as structured light sensors that emit a light beam and use a two-dimensional digital image sensor to collect image data for a three-dimensional image from a light spot generated when a target is illuminated by the light beam, binocular three-dimensional image sensors that collect three-dimensional images using two or more cameras in a binocular imaging configuration, three-dimensional lidar (light detection and ranging) sensors, three-dimensional high-frequency sensors, or other sensors that collect three-dimensional image data), cameras (e.g., infrared and / or visible cameras having corresponding infrared and / or visible digital image sensors, and / or ultraviolet light cameras), eye-tracking sensors (e.g., eye-tracking systems based on image sensors, and, if desired, light sources that emit one or more light beams that are tracked using image sensors after being reflected from the user's eyes), touch sensors, buttons, capacitive proximity sensors, infrared proximity sensors, and other light sensors. Examples of sensors include base (optical) proximity sensors, other proximity sensors, force sensors, switch-based contact sensors, gas sensors, pressure sensors, humidity sensors, magnetic sensors, audio sensors (microphones), ambient light sensors, optical sensors for performing spectral measurements and other measurements relating to target objects (e.g., by emitting light and measuring reflected light), microphones for collecting voice commands and other audio inputs, distance sensors, motion, position, and / or orientation sensors configured to collect information relating to motion, position, and / or orientation (e.g., accelerometers, gyroscopes, compasses, and / or inertial measurement units including all of these sensors or subsets of one or two of these sensors), buttons and other sensors for detecting button press input, joysticks with sensors for detecting joystick movement, keyboards, and / or other sensors. The wireless power transmitter 12 may have one or more input / output devices 68 (e.g., input and / or output devices of the types described in relation to input / output device 56).

[0047] The wireless power transmitter 12 and / or wireless power receiver 24 can communicate wirelessly using in-band or out-of-band communication. The wireless power transmitter 12 may have, for example, a wireless transceiver circuit 40 that wirelessly transmits an out-of-band signal to the wireless power receiver 24 using an antenna. The wireless transceiver circuit 40 may be used to wirelessly receive an out-of-band signal from the wireless power receiver 24 using an antenna. The wireless power receiver 24 may have a wireless transceiver circuit 46 that transmits an out-of-band signal to device 12. The receiver circuit in the wireless transceiver 46 can receive an out-of-band signal from the wireless power transmitter 12 using an antenna. In-band transmission between the wireless power transmitter 12 and the wireless power receiver 24 may be performed using coils 36 and 48. In one exemplary configuration, in-band data can be delivered from a radio power transmitter 12 to a radio power receiver 24 using frequency-shifted modulation (FSK) of one or more parameters of the radio-transmitted power (e.g., voltage, current, etc.), and in-band data can be delivered from the radio power receiver 24 to the radio power transmitter 12 using amplitude-shifted modulation (ASK) of one or more parameters of the radio-transmitted power (e.g., voltage, current, etc.). Power may be delivered wirelessly from the radio power transmitter 12 to the radio power receiver 24 during these FSK and ASK transmissions.

[0048] The wireless power transmitter 12 and wireless power receiver 24 may be able to communicate information such as received power and other power level estimates in order to control wireless power transmission. However, the technology described above does not require the transmission of personally identifiable information to function. With due consideration, it should be noted that insofar as any implementation of this charging technology involves the use of personally identifiable information, the implementer should adhere to privacy policies and practices that are generally recognized as meeting or exceeding industry or government requirements for maintaining user privacy. In particular, personal data should be managed and handled in a manner that minimizes the risk of unintended or unauthorized access or use, and the nature of authorized use should be clearly indicated to the user.

[0049] The control circuit 16 may include an external object measuring circuit 41 that can be used to detect whether an external object (including, but not limited to, “foreign objects”) is present on or near the charging surface of the housing of the wireless power transmitter 12 (for example, to detect an object on or adjacent to the top of the charging mat or pack). The housing of the wireless power transmitter 12 may have polymer walls, walls of other dielectric materials, metal structures, fabrics, and / or other housing wall structures surrounding the coil 36 and other circuits of the wireless power transmitter 12. The charging surface may be a flat outer surface of the upper housing wall of the wireless power transmitter 12, or an outer surface having other shapes (e.g., concave, convex, etc.). The circuit 41 can detect foreign objects such as coils, paper clips, and other metal objects, and can detect the presence of the wireless power receiver 24 (for example, the circuit 41 can detect the presence of one or more wireless power receiving coils 48). During object detection and characterization, the external object measurement circuit 41 can be used to measure coil 36 and / or other coils, such as an optional additional foreign object detection coil within the wireless power transmitter 12, to determine whether a wireless power receiver 24 and / or a foreign object is present on or near the wireless power transmitter 12.

[0050] In an exemplary configuration, the measurement circuit 41 of the control circuit 16 may include signal generator circuits, such as pulse generators, that can supply control signals to the inverter 61. These control signals may cause the inverter 61 to generate impulses so that the impulse response can be measured by the circuit 41 (for example, by using a voltage sensor, an analog-to-digital converter configured to convert analog voltage measurements to digital voltage measurements, and / or other sensing circuits). The measurement circuit 41 may also have an AC power supply and / or other circuits for performing measurements on the coil 36.

[0051] In some embodiments, quality factor measurements can be performed on the coil 36 to determine whether foreign matter is present. These quality factor measurements may include, and are not limited to, measurements of various observables of the radio power system. Such factors may include, but are not limited to, the resonant frequency, coupling coefficient, self-inductance, and combinations thereof and other observables. In this description, Q factor measurements are illustrative, but measurements of other observables may be substituted unless the context clearly indicates otherwise. For example, the quality factor (Q factor) of the coil 36 can be measured by direct impedance measurements and / or analysis of the impulse response. Measurements of the Q factor of the coil 36 (including measurements of the change in the Q factor from a baseline value) can be performed at any appropriate time, such as before transmitting radio power from the radio power transmitter 12 to the radio power receiver 24. This may include measurements performed in "open air," meaning that the radio power receiver 24 is not present, and / or measurements performed in a "combined" state, meaning that the radio power receiver 24 is present and coupled to the radio power transmitter 12. In the open air case, if the Q factor deviates beyond a threshold amount (causing a "deviation" in the Q factor), and the object causing the Q factor deviation does not respond to subsequent digital pings or other attempts to establish communication, the radio power transmitter 12 may conclude that a foreign object is present on the coil 36 and may discontinue radio power transmission and / or take other appropriate action (e.g., by stopping power transmission by transmitting power at a limited level lower than the level acceptable if no foreign object is detected). In the combined case, the introduction of a foreign object can be detected during or after the initiation of radio power transmission using combined Q factor measurements. Such an event may similarly cause either suppression of radio power transmission and / or a reduction of the power level to a limited level, as described above.Generally, Q-factor measurements, whether in open air or combined, can be performed using the same hardware and methods, and the control techniques implemented by each control circuit can be configured to respond appropriately to Q-factor (or resonant frequency) deviations based on appropriate thresholds and logic for each regime.

[0052] Figure 2 shows an exemplary circuit in a wireless power transmission system 8 that enables measurement of the Q factor of coil 36. The wireless power circuit in Figure 2 may include a wireless power transmitting circuit 52 in a wireless power transmitter 12 and a wireless power receiving circuit 54 in a wireless power receiver 24. During operation, a wireless power signal 44 may be transmitted by the wireless power transmitting circuit 52 and received by the wireless power receiving circuit 54. As shown in Figure 2, the wireless power transmitting circuit 52 may include an inverter circuit 61.

[0053] An inverter circuit (inverter) 61 may be used to provide a signal to the coil 36. During radio power transmission, the control circuit of the radio power transmitter 12 may supply a signal to the control input 82 of the inverter circuit 61 causing the inverter 61 to supply an alternating current (AC) drive signal to the coil 36. Circuit components such as a capacitor 70 may be coupled in series with the coil 36 as shown in Figure 2. When an alternating current (AC) signal is supplied to the coil 36, a corresponding AC electromagnetic signal (radio power signal 44) may be transmitted to a nearby coil, such as an exemplary coil 48 in the radio power receiving circuit 54, which can induce an AC current signal corresponding to the coil 48. A capacitor such as capacitor 72 may be coupled in series with the coil 48. A rectifier 50 may receive the AC current from the coil 48 and the corresponding DC power (e.g., DC voltage V) at its output terminal 76. rect It can generate (a certain amount of power). This power can be used to supply power to a load.

[0054] The wireless power transmitter 12 may have a measurement circuit for monitoring the signal on the coil 36. This circuit may include, for example, a voltage sensor 90 (e.g., a voltage sensing circuit coupled to and / or formed as part of an analog-to-digital converter). A current source 92 and / or inverter 61 may also be used to supply a signal to the coil 36 during foreign object detection operation (e.g., so that Q can be measured for the coil 36). In some embodiments, the Q factor measurement can be performed using a direct measurement of the impedance of the coil 36 by an AC current source. The measurement of Q may be performed when a wireless power receiving device 24 is present ("combined Q measurement") and / or when a wireless power receiving device is absent ("open-air" measurement). In some applications or embodiments, periodic open-air Q measurements may be performed when the wireless power receiver 24 is absent, and / or periodic combined Q measurements may be performed when the wireless power receiver 24 is present. By monitoring changes in Q (open-air or combined), the presence of a foreign object can be detected and appropriate action can be taken.

[0055] In the first exemplary Q-factor measurement configuration, the control circuit of device 12 can cause the inverter 61 to supply signal pulses to coil 36, and a measurement circuit such as a voltage sensor 90 is used to measure the corresponding impulse response. Due to resonance in the circuit of Figure 2, the application of signal pulses to coil 36 generates a ringing signal with an attenuated envelope such as the attenuated envelope 94 shown in Figure 3. The attenuated envelope is,

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number

[0056] If desired, the capacitor 70 in Figure 2 may be implemented using an adjustable capacitor configuration, such as a switching circuit or a capacitor circuit having multiple capacitors, which can be selectively switched and used under the control of the control circuit 16, thereby adjusting the capacitance value in the resonant circuit and thereby adjusting the resonant frequency. In a configuration in which the capacitor 70 has a selectable or otherwise controllable value, a first value (e.g., C1) can be used when the impulse response of the radio power transmission circuit is being measured to determine Q (as described in relation to Figure 3), and a second value (e.g., C2) can be used when the radio power transmission circuit is transmitting the radio power signal 44. In other embodiments, a single capacitance value can be used for both operations.

[0057] In the second exemplary Q-factor measurement configuration, the value of Q can be obtained from a direct measurement of the impedance of coil 36. Figure 4 is a schematic of the radio power transmission circuit and measurement circuit of Figure 2, showing how the parasitic resistance R can relate to the resonant circuit. In the direct impedance measurement technique, a small current can be injected into coil 36 from a current source 92, and a voltage measurement can be made using a voltage sensor 90. The magnitude of the injected current can be low enough to allow current to be injected without using a high-power field-effect transistor. The current may be an alternating current (AC) current at a frequency selected to optimize the ability to detect the presence of foreign matter based on the LC tank design, for example. In some cases, this may be a frequency of 125 kHz. However, depending on the design, higher or lower frequencies can be used. For example, another design may have a range of 150-300 kHz, but any suitable frequency can be used. In any case, this frequency can be selected independently of the resonant frequency associated with the radio power transmission circuit. The complex impedance of coil 36 can then be determined at this frequency, and the value of Q can be estimated from the measured impedance angle θ. Figure 5 shows the equations related to determining the complex impedance Q (coil Q factor) from the angle and arbitrary values ​​of inductance L and resistance R (real part of AC impedance) that can be calculated from direct impedance measurements. In the equations in Figure 5, I is the injected AC current and V is the resulting voltage measured by the voltage sensor 90.

[0058] The measurement circuit 41 of device 12 can be calibrated during manufacturing. For example, the Q factor (Q0) measured during the initial time when device 12 is being manufactured (using the first exemplary Q factor measurement configuration, the second exemplary Q factor measurement configuration, and / or additional Q factor measurement techniques) can be stored in device 12 as a baseline value for later use. Similarly, calibration can be performed for other observables to be measured, such as the resonant frequency. If desired, device-specific calibration operations may be performed so that each device 12 is individually calibrated with the corresponding individual baseline value of Q. When device 12 is operated in the field, device 12 can measure the current value of Q and compare this measurement of Q with the stored baseline value of Q0 from the factory. In this way, it is possible to determine the change in Q or other observables that indicates whether foreign matter or other external objects are present in the vicinity of the radio power transmitter 12.

[0059] If necessary, compensation techniques can be used to compensate for temperature, the effects of aging, and other effects that may induce drift in Q or other measurement parameters. While specific Q compensation techniques are described in the calibration examples below, other compensation techniques may be applied, and compensation for measured observables other than the Q factor (such as resonant frequency, coupling coefficient, etc.) may also be used. Temperature fluctuations can affect the parasitic resistance of components such as coil 36. Coil inductance L may also be temperature-dependent. Frequency changes and aging effects (e.g., mechanical wear) can affect the values ​​of components and therefore the measured value of Q. Compensating for these effects when comparing Q to Q0 can help improve the accuracy of foreign object detection measurements.

[0060] The baseline Q factor Q0 and the resonant frequency ω0, i.e., 2πf r This is measured during calibration (e.g., during the initial time in manufacturing) and can be given by equations 3 and 4.

number

Number

[0061] During the compensation operation, the current temperature T of the wireless power transmitter 12 can be measured using the temperature sensor 60 of the wireless power transmitter 12 (see, for example, FIG. 1). The temperature change ΔT from the temperature T0 measured during the calibration measurement during manufacturing is given by equation 9.

Number

[0062] The first exemplary compensation factor includes frequency compensation. As shown in the equation of FIG. 6, multiplying Q' by the compensation factor (ω0 / ω) can compensate for the change in the resonance frequency during the measurement of Q' with respect to the resonance frequency during the measurement of Q0 during manufacturing. The second exemplary compensation factor relates to the temperature dependence of inductance and resistance. As shown in the equation of FIG. 6, Q' can be multiplied by the compensation factor (1 + κ R ΔT) / (1 + κ L ΔT), where κ R is the resistance temperature change coefficient and κ[[ID=�8]] Lis the inductive temperature coefficient. The values ​​of these temperature coefficients may be influenced by the design of the radio power transmitter 12 and, if desired, can be determined empirically by performing measurements on one or more representative units of the radio power transmitter 12 during manufacturing. A third exemplary compensation coefficient is the AC resistance R of the coil 36 from the baseline value. AC and the DC resistor R of coil 36 DC This includes compensating for the shift. Using this resistance compensation technique, the current value of the quality factor can be compensated based on the compensated value of the total inductive coil resistance associated with the radio power transmitting coil 36. The coil 36 can be characterized by a total inductive coil resistance value having a DC portion and an AC portion. During compensation operation, the control circuit 16 can compensate for changes in the total inductive coil resistance by calculating a compensated value of the total inductive coil resistance from the sum of the baseline DC portion of the total inductive coil resistance measured at an initial time and the current AC portion of the total coil resistance. This compensated total inductive coil resistance value can then be used to compensate the current quality factor using the compensated total inductive coil resistance. As shown in the equation in Figure 6, the resistance-based compensation factor is the measured baseline DC resistance (R) obtained during the calibration measurement in manufacturing. DC,0 ), the baseline AC resistance (R) obtained during calibration measurement in manufacturing AC ), and the AC resistance R as a function of the change in the resonant frequency ω (e.g., 50 mΩ per 100 kHz or other appropriate value) obtained during calibration measurements in manufacturing. AC This can be based on the value of η, which is the coefficient of change of the parameter R. meas The measured AC resistance R AC And the measured DC resistance R DC It is equal to the sum of the two.

[0063] In the example in Figure 6, all three of these exemplary compensation coefficients are applied to the measured Q' value (for example, Qcomp is determined by compensating Q' based on the frequency change and the effects caused by the frequency change, and based on the effects caused by the temperature change). In general, one or two of these compensation techniques and / or other compensation techniques may be used to calibrate the Q factor measurement based on the measured temperature, resonant frequency, and / or other variables. As described in the example above, the compensated Q factor Qcomp may be generated based on the temperature and frequency measurements. This value can then be compared to a baseline value of Q measured during manufacturing and stored in device 12 for use in later comparisons. If necessary, the compensation calculation may be performed on a baseline Q factor to generate a compensated baseline Q, rather than performing the compensation operation on the field-measured Q factor. A technique in which the compensation operation is performed on the field-measured Q factor rather than the baseline Q factor is described herein as an example.

[0064] Figure 7 shows an exemplary flowchart of operation for detecting foreign objects using the wireless power transmission system 8. In this embodiment, power delivery can be suppressed when a foreign object is detected. It is also possible to simply flag the detection of a foreign object for use as additional information when determining an appropriate power delivery level during the power delivery phase. For example, the maximum power level used during the power delivery operation may be reduced to a predetermined level lower than the maximum power level in response to the detection of the presence of a foreign object.

[0065] During the operation of block 100, the radio power transmitter 12 may measure the current value of Q using a first exemplary Q-factor measurement configuration (e.g., applying an impulse using inverter 61 and measuring Q from the envelope 94 of the impulse response) or a second exemplary Q-factor measurement configuration (e.g., deriving Q from a direct impedance measurement of coil 36, which is performed by injecting current into coil 36 using AC current source 92). Measurement of Q using these or other suitable Q-factor measurement techniques may be referred to as low-power ping (LPP) or analog ping operation.

[0066] During the operation of block 102, the value of the change in Q (for example, the Q factor deviation value Q) defl ) can be determined. During the operation of block 102, compensation techniques such as the compensation techniques described in relation to Figure 6 can be applied to compensate for the measured value of Q or the baseline value of Q (i.e., Q0) stored in the radio power transmitter 12 during manufacturing. defl The value of can be calculated, for example, using formula 10.

number

[0067] During the operation of block 103, the control circuit of the wireless power transmitter 12 can determine whether Q is stable. If Q is changing rapidly (for example, due to the movement of an external object across the charging surface of the wireless power transmitter 12 while the measurement is being taken), Q defl The value of may not be stable enough, and the operation can return to block 100. Then, a new measurement of Q can be obtained while block 100 is in operation. As long as Q is not stable, a new Q measurement can be obtained in this way every 0.1 seconds (or at another suitable sampling rate). defl If the consecutive values ​​of change by less than a predetermined threshold amount (e.g., 1%), Q is used to determine whether a foreign object is present. defl The value can be considered stable enough to allow analysis, and the operation can proceed to block 104.

[0068] During the operation of block 104, the wireless power transmitter 12 Q defl The value can be compared to a predetermined threshold TH (e.g., 3% or another appropriate value). defl If Q does not exceed the threshold (for example, if the measured value of Q is not reduced by more than 3% relative to the baseline Q), the wireless power transmitter 12 can conclude that no external object is present (for example, the wireless power receiving device 24 is not present and no foreign object is present). Then, in block 100, the measurement operation can continue. However, during the operation of block 104, Q deflIf it is determined that the threshold is exceeded, device 12 can conclude that the measured Q has changed by more than a threshold amount relative to the baseline Q0 (for example, Q is at least 3% lower than Q0), and therefore some type of external object is present (either a foreign object or the radio power receiving device 24). The operation then proceeds to block 106, where these two possibilities can be distinguished.

[0069] During the operation of block 106, the radio power transmitter 12 may attempt to communicate wirelessly with the radio power receiver 24. For example, device 12 may send a radio digital request using in-band communication. A radio digital request may be used to request that the radio power receiver 24 acknowledge its presence by wirelessly sending a corresponding digital response to the radio power transmitter 12 using in-band communication. This digital communication request process is sometimes called a digital ping. During the operation of block 108, the radio power transmitter 12 may determine whether a response to the digital ping has been received from the radio power receiver 24 to indicate the presence of the radio power receiver.

[0070] If a radio power receiver 24 is present on the charging surface of the radio power transmitter 12, the radio power receiver 24 responds to a digital ping with a radio digital response. This response may include information such as a digital identifier corresponding to the type of radio power receiver 24 present. Depending on whether the radio power transmitter 12 determines during the operation of block 108 that a mobile phone, watch, or other radio power receiver 24 is present, it may transmit a radio power signal 44 to the device 24 (for example, during the operation of block 110). Subsequent combined Q measurements may be performed similarly during this period, as will be described in more detail below. Alternatively, if no radio power receiver 24 is present on the charging surface of the radio power transmitter 12, the radio power transmitter 12 will not receive any acknowledgment from the radio power receiver 24. Depending on whether the radio power receiver 24 is present during the operation of block 108, the radio power transmitter 12 may conclude that a foreign object (which caused the measured Q deviation) is present, and the operation may proceed to block 112.

[0071] During block 112, the radio power transmitter 12 can monitor Q to determine when any foreign matter present has been removed. In particular, Q can be measured during the operation of block 114, as described in relation to the Q measurement of block 100. defl The value can be calculated in block 116. The operation of block 118 is Q defl This may involve comparing it to a threshold TH or another threshold. If the foreign matter remains present, Q defl The value remains above the threshold, and additional measurements can be performed in block 114. However, once the foreign object is removed, the process returns to block 100, where the radio power transmitter 12 can determine whether a radio power receiver 24 is present, and if so, can begin supplying radio power to the radio power receiver 24.

[0072] Q deflIn determining Q, the radio power transmitter 12 can perform a comparison between the measured Q and a baseline value of Q acquired during manufacturing and stored in the radio power transmitter 12 for future use. Temperature changes, frequency changes, coil resistance changes, and other changes may affect Q0, and therefore Q0 can be continuously updated if desired. In an exemplary configuration, a filter is used to update the Q baseline based on a newly measured Q reading whenever it is determined that there are no external objects on the charging surface of the radio power transmitter 12. For example, if the radio power transmitter 12 is operating block 104, defl Each time it determines that the value is not greater than the threshold, the wireless power transmitter 12 can conclude that no foreign objects and wireless power transmitting devices are present. Thus, the wireless power transmitter 12 can conclude that the most recent measurement of Q from block 100 is, in effect, an updated open-air Q value (e.g., the current Q value that can be used as a filter input) that can be used at least partially when updating Q0.

[0073] Therefore, in this embodiment, Q defl Each time it is determined that Q is not greater than the threshold TH, the updated value of Q0 can be stored in the wireless power transmitter 12 at point P1 in the flowchart of Figure 7. When updating Q0, the current value of Q (measured during the most recent visit to block 100) can be incorporated into Q0 using an appropriate filtering scheme (e.g., using a weighted historical average, using an averaging scheme that does not emphasize noisy data, or using other filtering configurations). By updating Q0 with the current measurement data in this way, the effect of aging on the baseline Q value can be reduced.

[0074] In an exemplary configuration, the wireless power transmitter 12 can update Q0 with the current measured value of Q using a low-pass filter. Let q[n] be a valid Q deviation sample. An example of a low-pass filter for Q is a single-pole filter (see, for example, equation 11), where α∈[0,1] and is close to 1.

number

number

[0075] Updating the baseline Q value at point P1 may include performing a separate filtering operation following each measurement of Q in block 100. If desired, the number of filtering operations per unit time (and therefore the number of times per unit time the updated Q baseline value is calculated and stored in device 12) can be reduced by performing the filtering operation at point P2 instead of P1. In this type of configuration, the Q value measured during the operation of block 100 may be stored (cached) by the control circuit 16 each time point P1 is reached (e.g., each time it is determined that no foreign object is present). If the operation of block 104 determines that the latest Q value exceeds the threshold TH, processing may proceed to block 106, where a digital ping is performed. During the operation of block 108, the control circuit 16 may determine whether (a) a response corresponding to the digital ping has not been received (in which case a foreign object is present and processing proceeds to block 112), or (b) a radio digital response has been received from device 24. At this point (for example, at point P2), the wireless power transmitter 12 can know that the wireless power receiver 24 has just been placed on the charging surface of the wireless power transmitter 12. Before starting power delivery in block 110, the wireless power transmitter 12 can retrieve the last cached value of Q at point P1 (representing the Q factor measurement when no foreign objects or other external objects are present on the device 12), and use this retrieved current value of Q to update the Q baseline value.

[0076] In this method, the filtering operation used to update the Q baseline value may only be performed when it is determined that a new radio power receiver 24 is present (and no foreign objects are present). The filtering operation can be performed using the most recently acquired value of Q when no external objects were present (e.g., the cached value of Q at point P1 when no external objects were present). Although the Q value storage operation still exists each time point P1 is reached, the calculation of the updated baseline Q value using the filter may be performed less frequently (e.g., only when P2 is reached). Updating the baseline Q factor only when it is determined that no radio power receiving device is present and no foreign objects are present ensures that the baseline quality factor value is adjusted for aging and other effects that may cause quality factor measurements to drift over time, but without involving as many separate filtering operations as when the filtering operation is performed at point P1.

[0077] In addition to periodically updating the baseline value of Q (for example, at either point P1 or point P2), the control circuit 16 may periodically update the value of the threshold TH used during the comparison operation of block 104 (for example, an adjustable threshold TH may be used instead of a fixed predetermined value). For example, the value of TH can be updated based on a history of Q-factor measurements or other measurements (e.g., Q-factor measurements taken when no external object was present and cached at point P1) using a low-pass filtering operation or other filtering operation. This filtering operation for updating the value of TH may be performed at point P2 (for example, when it is determined that no foreign object is present) using measurements such as one or more cached Q-factor measurements taken when no wireless power receiving device or foreign object was present.

[0078] If desired, Q deflThe value may be compared to several different thresholds (for example, to determine whether a small or large foreign object is present). Device 12 can then take different actions depending on whether a small or large foreign object is present. For example, radio power may be transmitted at a limited power level if a small foreign object is detected in the presence of a radio power receiving device, but may be completely withdrawn in the presence of a large foreign object. In this context, "small" or "large" may refer to the physical size and / or other physical characteristics of the device, which correlate with the level of heating that such a foreign object may be expected to experience at various radio power transmission levels.

[0079] As an example, consider Figure 8, which illustrates the operation of a wireless power transmitter 12 in a system with multiple foreign object detection thresholds. In the example in Figure 8, the wireless power transmission system 8 detects a lower first threshold TH air (For example, 3%, or any other appropriate value such as a value less than 3% or a value greater than 3%) and a higher second threshold TH FO (For example, a value of 6%, greater than or less than 6%, or any other suitable value higher than the first threshold). The wireless power transmitter 12 can operate in states 120, 122, 124, and 126. Transitions between these states may occur according to transition rule 128. Threshold TH air and TH FO The value can be appropriately adjusted to distinguish moderate foreign matter (e.g., objects with a relatively small amount of metal and / or metal with moderate conductivity) from strong foreign matter (e.g., objects with more metal and / or metal with greater conductivity). These "moderate" and "strong" foreign matter may correspond to the "small" and "large" foreign matter described above. Wireless power transmission may be suppressed until free air is visible in the case of strong foreign matter. However, by setting the threshold sufficiently high, the implementation can choose to avoid using the "strong foreign matter" condition.

[0080] As shown in Figure 8, in block 122, the wireless power transmitter 12 is Q deflThis can be compared with the first and second thresholds, Q defl It can be determined that the value is lower than the first threshold. In this scenario, the wireless power transmitter 12 can conclude that no foreign matter is present and therefore can set the power delivery level of the wireless power signal 44 to a relatively high power level (power level 2). The power can then be wirelessly transmitted from the wireless power transmitter 12 to the wireless power receiver 24 during the power delivery operation of block 126.

[0081] In block 120, Q defl Since it is greater than the first threshold, it may be being judged as the presence of a foreign object. Q defl It may also be determined that it is below a second threshold. As a result, the radio power transmitter 12 can conclude that a foreign object is present, but it is not a large or large foreign object. Therefore, the radio power transmitter 12 can proceed to wirelessly supply power to the radio power receiver 24 during the operation of block 126. Since power is supplied to the radio power receiver 24 in the presence of power or a moderate foreign object, the level at which power is wirelessly transmitted (i.e., the maximum power level) can be reduced to a relatively low power level (e.g., power level 1, which is less than power level 2). This can help prevent or limit the heating of small / moderate foreign objects. In block 124, Q defl Since this value is greater than the second threshold, it is possible to detect the presence of a large or strong foreign object. In this situation, the wireless power transmitter 12 can stop wireless power transmission.

[0082] The embodiments described above are merely illustrative, and different control logics may be implemented, including multiple thresholds, multiple power levels, and variations in whether wireless power transmission is limited or completely suppressed depending on each threshold. In addition, further details such as Q measurement techniques, compensation methods, and accuracy improvements for such measurements are described in the applicant's U.S. Patent Application No. 18 / 327721, “Wireless Power Systems with Foreign Object Detection,” filed June 1, 2023, which is incorporated herein by reference in its entirety.

[0083] As described above, foreign object detection in a wireless power transmission system can also be based on a combined Q measurement, either separately from or in conjunction with the open-air Q measurement described above. At a high level, the operating principle of the combined Q measurement is as described above. That is, when the wireless power transmitter 12 is coupled to the wireless power receiver 24, the corresponding control circuit 16, measurement circuit 41, and power transmission circuit 52 may be configured to provide a signal that enables the measurement of the coupled Q factor (or other magnetic parameters (one or more) as described above). This signal may take the form of an impulse response and a ringdown, as described above with respect to Figures 2 and 3. In addition, or alternatively, this measurement may be based at least in part on a complex impedance measurement, as described above with respect to Figures 4 and 5. The Q deviation or other magnetic parameters thus obtained may be used in conjunction with the measurement of the system resonant frequency for foreign object detection. The system resonant frequency may be derived from an impulse-based measurement of the Q deviation, which is performed as described with reference to Figures 2 and 3. More specifically, the resonant frequency is a coefficient that characterizes the ring-down envelope 94 (along with the Q factor) and / or can be measured directly by referring to the ringing waveform. Alternatively, the system resonant frequency may be determined by, for example, sweeping the frequency of the applied waveform and identifying the peak associated with the resonant frequency using a circuit such as one used for complex impedance measurement, as described with reference to Figures 4-5.

[0084] For a given radio power transmitter 12, one or more pairs of baseline combined Q values ​​and resonant frequency values, each corresponding to one or more reference receivers 24, may be acquired, for example, during the manufacture of the radio power transmitter 12. Such one or more pairs of baseline combined Q values ​​and resonant frequency values ​​may be compared with combined Q measurements and resonant frequency measurements taken during operation in order to detect foreign objects that may be carried near the radio power transmission system 8 during operation. In some cases, the number of potential radio power receivers 24 may be such that it is difficult to measure and store pairs of values ​​for each possible transmitter / receiver combination. In such cases, the ecosystem scaling principle, which is described in more detail below, may be employed to make the situation more manageable by storing fewer baseline value pairs and providing a mechanism for calculating modified baseline value pairs corresponding to a particular transmitter / receiver combination.

[0085] Baseline values ​​or modified baseline values ​​can be compared to measurements in a two-dimensional space where the presence and absence of foreign matter are sufficiently separated. Such a space can be conceived as a magnetic state space where normal operation (no foreign matter) and a scenario in which foreign matter is present and undetected and can be heated are sufficiently separated to be distinguishable. An example of such a space is shown in Figure 9 by plot 900. Plot 900 plots a first observable (x(f,Q), e.g., measured resonant frequency deviation) as a function of the resonant frequency and Q factor on the x-axis against a second observable (y(f,Q), e.g., measured combined Q deviation) as a function of the resonant frequency and Q factor on the y-axis. The measured resonant frequency deviation may be the difference between the resonant frequency measured during operation and the baseline resonant frequency (optionally modified by ecosystem scaling calculations, as described in more detail below). The measured combined Q deviation may be the difference between the measured combined Q value during operation and the baseline Q factor (optionally modified by ecosystem scaling calculations, as described in more detail below). When no foreign matter is present, the combined Q and resonant frequency deviation (or deviations of other magnetic parameters as described above) generally appear in region 905. When foreign matter is present, the combined Q and resonant frequency deviation generally appear in region 903. Figure 9 is based on the fQ space. 2 In the 1 / fQ space, as will be discussed later with reference to Figure 17A, the relative positions between regions corresponding to the presence or absence of foreign matter can be reversed. Therefore, the relative positions between these regions can differ depending on the selected function.

[0086] These two regions, namely the separation between the absence of foreign matter and the presence of foreign matter, can be described by curve 901. Curve 901 may also be a linear function of the following form:

number

number

[0087] Figure 10 shows a flowchart of the foreign object detection method 1000 using the combined Q measurement described above. Starting from block 1007, the system can optionally execute the open-air Q-based foreign object detection routine described above. Accordingly, the system can start power transmission at an appropriate level as described above (block 1009). The exact operation of the open-air Q portion of the combined Q foreign object detection method 1000 can be modified depending on the specific implementation and / or in some embodiments it can be omitted entirely as needed. The combined Q portion of the foreign object detection method 1000 starts in block 1011, where the combined Q and resonant frequency are measured as described above. Then, in block 1013, the system (e.g., the control circuit 16 of the radio power transmitter 12) can determine whether a foreign object is present by comparing the measured combined Q with the resonant frequency as described above. For example, the processing circuit can compare the measured combined Q value and resonant frequency value with reference values ​​stored in the device and determine whether the associated deviation corresponds to region 905 (Figure 9) (no foreign matter present) or region 903 (Figure 9) (foreign matter present) in the magnetic state space. If it is determined that no foreign matter is present, the process proceeds to block 1014, which can enable the continuation or resumption of wireless power transmission at a relatively high power level. Control can return to block 1011, which enables periodic combined Q and resonant frequency measurements at desired intervals during the power transmission operation initiated in block 1009, enabling ongoing / continuous combined Q foreign matter detection.

[0088] Alternatively, if a foreign object is detected in block 1013, the processing circuit can determine, as described above, whether the detected foreign object is a "moderate" or "small" foreign object, or a "strong" or "large" foreign object. Furthermore, more than two levels of foreign object classification can be provided. Generally, moderate / small foreign objects are those that allow wireless power transmission at a limited or lower power level without increasing the heating level of the foreign object (e.g., exceeding a threshold). Similarly, strong / large foreign objects may require suppression or temporary suspension of wireless power transmission to prevent increased heating levels. What constitutes an increased heating level and thus defines the foreign object classification as moderate / small or strong / large (or further levels) may vary depending on the application or embodiment. However, it may be desirable that the combined Q and / or resonant frequency deviations differ sufficiently between such classes to allow for easy analysis by the processing circuit (e.g., the control circuit 16 of the wireless power transmitter 12). Based on this classification, if in block 1015 the detected foreign object is determined to be small / medium in size, the power transmission level can be reduced in block 1017, and control returns to block 1011, enabling continuous / periodic combination Q foreign object detection. If the foreign object is subsequently removed, power transmission can be resumed at a higher level (block 1014). Alternatively, if the foreign object remains, the flow again proceeds along the same 1015-1017-1011 path described above. As yet another alternative, if in block 1015 the detected foreign object is determined to be strong / large rather than medium / small, control proceeds to block 1019, and wireless power transmission is interrupted or suppressed. Then, if the open-air ping process determines that the foreign object is no longer present, control returns to block 1007 for the resumption of power transmission. If the open-air ping function 1007 is omitted from a particular embodiment or application, control can return to any path that results in the initiation of wireless power transmission (e.g., block 1009).

[0089] The above description is merely one example of a combination Q-based foreign object detection and subsequent wireless power transmission control technology. Various modifications to this configuration are possible. For example, the classification of detected foreign objects as moderate / small or strong / large can be completely omitted, and the detection of any foreign object in the combination Q phase can result in a temporary suspension / suppression of wireless power transmission. Similarly, there may be multiple classifications of foreign objects, each with a different power reduction limit. Also, as mentioned above, the initial open-air Q measurement foreign object detection algorithm can be omitted or modified from the example above. Numerous other variations and permutations are possible.

[0090] Figure 11 shows a sequence of combined Q measurements associated with stationary / static detection that may be used for foreign object detection. The sequence is shown as a plot 1100 of measured combined Q deviations (on the vertical axis) versus time (on the horizontal axis), where each combined Q measurement is a point. The combined Q deviation is the difference between the combined Q value measured at that moment and a reference combined Q value stored in a device, e.g., a radio power transmitter 12. The initial reference value may be programmed into the unit at the time of manufacture and may be updated periodically as described elsewhere in this specification.

[0091] The initial sequence 1121 of Q deviation values ​​of 0 corresponds to a situation where neither foreign object nor radio power receiver object is present. These intervals may provide an opportunity to update the stored baseline value, as described elsewhere in this specification. Starting at approximately 2 seconds in exemplary plot 1100, the Q deviation values ​​begin to increase but do not have a steady value over a series of samples 1123. This corresponds to the time during which an object, which may be the radio power receiver or a foreign object, is carried near the transmitter. During this interval, it may be desirable for the processing system, e.g., the control circuit 16 or the radio power transmitter 12, to do nothing until the Q deviation reading stabilizes. Nevertheless, in some situations, e.g., with very large Q deviations, it may be desirable to take action more quickly to reduce or suppress power transmission. In any case, the processing circuit can apply appropriate averaging or filtering to the Q deviation values ​​to determine whether the system has reached a stable steady state point. Such a steady state may be indicated when the sequence of measured Q deviation values ​​does not show change, as in sample 1125. Sample 1125 indicates that the system has stabilized at a Q deviation of approximately 0.5 (other Q values ​​are similarly possible). This stabilized Q deviation (and its associated resonant frequency value) can then be used to perform the combined Q foreign object detection described above. In some cases, a sequence of combined Q measurements (rather than deviations), resonant frequency measurements, or resonant frequency deviations can be used to detect whether the system has reached a steady-state operating condition when an object is brought nearby. In fact, in some applications, resonant frequency measurements and / or resonant frequency deviations may provide a better estimate of when the system is stable than combined Q value / deviation samples.

[0092] As described above, the use of combined Q measurements for foreign object detection may depend on baseline combined Q and resonant frequency measurements, which may differ for each possible radio-power transmitter and radio-power receiver pair. In some cases, multiple such baseline values ​​may be determined, for example, at the time of manufacture and stored in the radio-power transmitter as described above. However, as the number of potential transmitter / receiver pairs increases, this can quickly become impractical. Therefore, it may be desirable to provide one or more baseline value pairs for each transmitter based on one or more "reference" or "golden" receiver pairings. Each receiver may then be characterized with respect to one or more of the reference / golden receivers and may be provided with its own stored values ​​corresponding to such characterizations. For example, this can be implemented as various scaling factors with respect to the reference / golden receivers. The radio-power receiver may then provide its scaling factor to the radio-power transmitter, which can then calculate appropriate baseline combined Q factor and resonant frequency values ​​based on the stored reference values ​​and scaling factors. An exemplary technique for loss measurement scaling is described in the applicant's U.S. Patent Application No. 17 / 681363, filed February 25, 2022, entitled “Wireless Power Systems with Shared Inducive Loss Scaling Factors,” which is incorporated herein by reference in its entirety and summarized below with reference to Figures 2, 12, and 13.

[0093] As described above, Figure 2 shows an exemplary radio power circuit in a radio power transmission system 8 in an exemplary scenario in which a radio power transmitter is paired with a radio power receiver. The radio power circuit in Figure 2 includes a radio power transmitting circuit 52 in a radio power transmitter 12 and a radio power receiving circuit 54 in a radio power receiver 24. During operation, a radio power signal 44 is transmitted by the radio power transmitting circuit 52 and received by the radio power receiving circuit 54. The configuration in Figure 2 includes (as an example) a single transmitting coil 36 and a single receiving coil 48.

[0094] As shown in Figure 2, the wireless power transmission circuit 52 may include an inverter circuit 61. The inverter circuit (inverter) 61 may be used to provide a signal to the coil 36. During wireless power transmission, the control circuit of the wireless power transmitter 12 may supply a signal to the control input 82 of the inverter 61, causing the inverter 61 to supply an AC drive signal to the coil 36. Circuit components such as a capacitor 70 may be connected in series with the coil 36, as shown in Figure 2. A measuring circuit 41 in the wireless power transmitter 12 can perform measurements regarding the operating current and operating voltage within the wireless power transmitter 12. For example, a voltage sensor 41A can be used to measure the coil voltage on the coil 36, and a current sensor 41B can be used to measure the coil current through the coil 36. In other implementations, the voltage on a capacitor 70 may be measured, and the current through the coil may be estimated from that measurement.

[0095] When an AC current signal is supplied to coil 36, a corresponding AC electromagnetic signal (radio power signal 44) can be transmitted to a nearby coil, such as an exemplary coil 48 in the radio power receiving circuit 54. This can induce a corresponding alternating current (AC) signal in coil 48. A capacitor, such as capacitor 72, can be coupled in series with coil 48. The rectifier 50 can receive the AC current from coil 48 and the corresponding DC power (e.g., DC voltage V) at its output terminal 76. rect ) can be generated. This power can be used to power a load. The measuring circuit 43 in the device 24 can perform measurements regarding the operating current and operating voltage in the device 24. For example, the voltage sensor 43A can measure V rect The voltage sensor can measure the output voltage of the rectifier 50, or the current sensor can measure the coil voltage on the coil 48. The current sensor 43B can measure the rectifier output current of the rectifier 50, or the current sensor can measure the current of the coil 48.

[0096] Measurements performed by measurement circuits 41 and 43 may be processed to extract magnetic loss characteristics (e.g., coefficients or other parameters that characterize the amount of power loss in the radio power transmitter 12 and radio power receiver 24 and depend on the magnetic properties of the transmitter and receiver). These measurements may be stored within each device or exchanged between devices so that the radio power transmitter 12 (and, if desired, the radio power receiver 24) can use this information to accurately estimate any foreign matter power loss and / or other relevant parameters such as combined Q measurements and / or combined resonant frequency measurements.

[0097] If necessary, these measurements can be used to estimate how well the transmitter and receiver can transmit radio power. For example, these measurements can be used to estimate the magnetic coupling coefficient K, radio power transmission efficiency, estimated foreign object power loss, and / or other attributes of the combined transmitter-receiver pair. In addition to, or instead of, estimating foreign object power loss to determine whether foreign object is present and therefore whether radio power transmission should proceed, the system can use this information (e.g., estimated foreign object power loss and / or related coupling information and / or efficiency information) to determine whether the system should present a confirmation message to the user informing them that radio power transmission is proceeding properly (e.g., that the process was not interrupted by the presence of foreign object, possible misalignment, or other factors resulting in poor coupling). Exemplary confirmation messages include an audio output such as a chime and / or a visual output presented on the radio power receiver 24.

[0098] In general, any suitable information can be exchanged between devices within the system 8, and this information can be used in any suitable manner. Examples include the exchange of measured values, such as those obtained using measurement circuits 41 and 43, and the use of this information in determining whether foreign matter is present.

[0099] Following measurements using circuits 41 and 43, the amount of energy potentially absorbed by foreign matter in system 10 can be determined using equation 14.

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[0100] In Equation 14, P FO This represents the amount of electrical energy absorbed by any foreign matter present. OUT P represents the output power (for example, the output power of rectifier 50), IN represents the input power (for example, the input power to coil 36), and P LOSSTX This represents the power loss caused by the wireless power transmitter 12, PL OSSRX This represents the power loss caused by the wireless power receiver 24. OUT and P IN The value of can be measured (for example, using circuits 41 and 43). Using a mathematical model, P LOSSTX and P LOSSRX Functional representations can be generated, and these representations can be evaluated using measured operating parameters, such as measurements obtained using circuits 41 and 43. For example, in one exemplary modeling embodiment, P LOSSTX and P LOSSRX These can be calculated using equations 15a and 16a, respectively.

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[0101] In formulas 15a and 16a, I TX represents the transmitter current (e.g., coil current), and I RX R represents the receiver current (for example, the rectifier output current, or in some embodiments, the receiver coil current). AIRTX and R AIRRX The values ​​represent the AC coil resistance measured for coil 36 and coil 48, respectively. b, m, α and α DCThe value of is a model parameter (sometimes called the magnetic power loss coefficient) that characterizes the performance of the coupled radio power transmitter and radio power receiver pair in the radio power transmission system 8. Transmitter power loss P LOSSTX This is due solely to the transmitter coil power loss in the model of Equation 15a. Receiver power loss P LOSSRX It has a first component (the first term in Equation 16a) attributable to receiver coil power loss and a second component (consisting of the last two terms in Equation 16a) representing friendly metal loss (for example, loss due to eddy currents induced in the receiver when power is being transmitted). Parameter b may be called the transmitter coil loss parameter or coefficient. Parameter m may be called the receiver coil loss parameter or coefficient, and parameters α and α DC These may be called friendly metal loss parameters or friendly metal loss coefficients. Parameters b, m, α and α DC This depends on the magnetic interaction between the radio power transmitter 12 and the radio power receiver 24 when they are coupled, and may therefore be called the magnetic loss parameter or magnetic loss coefficient.

[0102] In an ecosystem where multiple different models of wireless power transmitting devices (e.g., different models of wireless power transmitter 12) and multiple different models of wireless power receiving devices 24 (e.g., different models of any of the devices) are available to the user, the magnetic loss parameter may vary depending on which particular wireless power transmitter and wireless power receiver are paired together. For example, when a Model I transmitter and a Model J receiver are paired, the amount of power loss in each device will be different from the amount of power loss experienced when these devices are paired with different devices.

[0103] To account for these variations and thereby ensure an accurate estimation of the foreign object power loss in Equation 14, a magnetic power loss parameter scaling factor (sometimes referred to as the scaling factor of the magnetic power loss coefficient) may be used. In particular, in an ecosystem with multiple different transmitter models and receiver models, the models of P LOSSTX and P LOSSRX in Equations 15a and 16a, which can be inaccurate, may be replaced by Equations 15b and 16b, respectively. [Number]

[0104] In Equation 15b, the transmitter coil loss parameter b from Equation 15a is replaced by a reference transmitter coil loss value b R (sometimes referred to as the transmitter coil loss coefficient) associated with the transmitter loss measured when the reference transmitter is coupled to the reference receiver. This value can then be scaled using the scaling factor g b . In Equation 16b, the receiver coil loss parameter m can be replaced by an m R (sometimes referred to as the receiver coil loss coefficient) associated with the receiver coil loss measured when the reference receiver and the reference transmitter are coupled together. This value can then be scaled using the scaling factor g m . In Equation 16b, the friendly metal loss parameters α and α DC can be replaced by reference friendly metal loss parameters (coefficients) α R and α RDC extracted using measurements performed on the reference transmitter and the reference receiver. The reference friendly metal loss parameters can be scaled by their respective scaling factors g α and g αDC . P LOSSTX (see, for example, Equation 15b) and P LOSSRXBy using a scaling factor when calculating (see, for example, Equation 16b), Equation 14 can be satisfactorily evaluated regardless of which model transmitter and receiver are paired with each other.

[0105] An exemplary operation involving determining the scaling parameters using the transmitter and receiver being measured is shown in flowchart 1200 of Figure 12. The operation in Figure 12 may be performed at design time, and the resulting scaling factors may be stored in production units. An exemplary operation involving the use of parameter scaling in the wireless power transmission system 8 is shown in Figure 13. The operation in Figure 13 may be performed at runtime (for example, when the transmitter and receiver are paired in preparation for the transmission of wireless power between the transmitter and receiver). In the examples of Figures 12 and 13, it may be assumed that the scaling factors for a particular model of transmitter (e.g., Model I transmitter) and a particular model of receiver (e.g., Model J receiver) are obtained using reference device measurements and are then used when the Model I transmitter is paired with the Model J receiver. In general, this process may be expected to be performed for a number of models of transmitters (e.g., models other than Model I) and a number of models of receivers (e.g., models other than Model J). Furthermore, any of the various models of a characterized transmitter may generally be paired by the user with any of the various models of a characterized receiver. This is because not all users own the same model of transmitter, nor do all users own the same model of receiver. In this example, the exemplary user pairs a Model I transmitter with a Model J receiver during the operation shown in Figure 13.

[0106] The operations involved in measuring the magnetic power loss parameter scaling factors of Model I transmitter and Model J receiver are shown in FIG. 12. During the operation of block 1290, a reference wireless power receiver is paired with a reference wireless power transmitter (either physically or by a simulated pairing such as a finite element analysis simulation pairing). The physical reference device can be obtained from a centralized source or can be constructed by different device manufacturers according to a worldwide prevalent reference design. Once paired, the reference wireless power transmitter and the reference wireless power receiver can start transmitting power. In particular, during the operation of block 1290, the reference wireless power transmitter can transmit a wireless power signal to the reference wireless power receiver while the internal operating parameters (e.g., the current and voltage of the transmitter and receiver) are being measured and stored. From these measurements, the reference magnetic loss parameters can be extracted (e.g., the values of reference magnetic loss parameters b R , m R , α R , and α RDC can be obtained). In a scenario where pairing simulation is used instead of measurements on physically paired devices, a finite element analysis simulation can be used to determine the LQK (inductance, Q factor, and coupling coefficient) of the coupled transmitter-receiver pair, and then a circuit simulation can be used to determine the expected current and voltage. Then, these simulated current and voltage can be used to determine the magnetic loss parameters.

[0107] After determining the reference magnetic loss parameters (either by physical measurement or simulation), the Model J receiver can be paired with the reference wireless power transmitter. While these devices are paired in simulation or while these devices are physically paired and wireless power is being transmitted from the reference wireless power transmitter to the Model J receiver, the loss parameter measurements of the Model J receiver can be obtained. In particular, during the operation of block 1292, the Model J loss parameter (coefficient) b RJ , mRJ , α RJ , and α RJDC The following can be obtained. The "J" in each of these parameters and the R (representing "reference") in each of these parameters indicate that the loss parameter is specific to a scenario in which the Model J receiver is operating with a reference radio power transmitter. Next, the scaling factor g of the Model J receiver b (Equation 15b) can be calculated using Equation 17 (and so on) and stored in all Model J wireless power receiving devices (for example, during manufacturing or later using updates).

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[0108] During the operation of block 1294, the Model I transmitter may be paired with a reference radio-power receiver. Power may be transmitted radio while the radio-power transmitter operating parameters (e.g., current and voltage) are being measured. From these measurements or simulations, the magnetic loss parameter m of the Model I transmitter can be determined. IR , b IR , α IR , and α IRDC This can be obtained. Then, using equations 18, 19, and 20, the scaling factor g of the transmitter for Model I can be obtained. m , g α , and g αDC It is possible to calculate this.

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[0109] An exemplary operation involving the use of scaling factors in a Model I transmitter and a Model J receiver in a scenario where the Model I transmitter and Model J receiver are paired by a user is shown in the flowchart of Figure 13. During the operation of Figure 13, a user having a Model J receiver and a Model I transmitter who wishes to wirelessly transmit power from the Model I transmitter to Model J pairs the Model I transmitter and the Model J receiver during the operation of block 1301 (for example, by magnetically coupling a Model I wireless power transmitter (e.g., a wireless charging pack, just one example) to a Model J wireless power receiver (e.g., a mobile phone, just one example)). During the operation of block 1302, the Model I transmitter and the Model J receiver can exchange information such as their pre-programmed scaling factors (e.g., using low-power inband communication or other wireless communication) and transmit power. For example, the Model J receiver can transmit to the Model I transmitter the value of the scaling factor gm obtained from a Model J measurement using a reference transmitter in block 1292 of Figure 12. The Model I transmitter uses a scaling factor g obtained from Model I measurements using a reference receiver in block 1294 of Figure 12. m , g α , and g αDC The value is transmitted to the Model J receiver. While power is being transmitted wirelessly from the Model I transmitter to the Model J receiver, the measurement circuit 41 in the wireless power transmitter and the measurement circuit 43 in the wireless power receiver can measure the operating parameters of the transmitter and receiver (e.g., coil current and voltage, rectifier output voltage and current, etc.). The measured values ​​of current and voltage can be exchanged between the wireless power transmitter and the wireless power receiver if desired (e.g., using in-band wireless communication). The information measured by circuits 41 and 43 is expressed using equations 15b and 16b. LOSSRX and P LOSSTX To calculate this, it can be used in conjunction with the exchanged scaling factor.

[0110] During the operation of block 1304, for example, the Model J receiver uses the rectifier current and rectifier voltage (their product is P OUTIt is possible to measure the scaling factor g received from the Model I transmitter during the operation of block 1202. m , g α , and g αDC In conjunction with this, the measured values ​​are used to evaluate equation 16b, thereby P LOSSRX This can be estimated. The scaling factor received from the Model I transmitter can provide the receiver J with information regarding the expected operating characteristics of the Model I transmitter with respect to receiver coil loss and friendly metal loss.

[0111] As an example, let's consider receiver coil losses. When receiver J is paired with a reference radio power transmitter, the scaling factor g m The value of is 1. Then, receiver J can determine the receiver coil loss using the first term of equation 16b (the receiver coil loss is m R ·R AIRRx ·(I RX ) 2 And, m R , R AIRRX , and receiver current I RX The value of is known to receiver J. However, in this situation, receiver J is not paired with the reference radiopower transmitter, but instead with transmitter I. Transmitter I may be predetermined to induce lower coil losses in the paired receiver than the reference transmitter, so during block 1302, the value of g passed by transmitter I to receiver model J is known. m The value of can be (for example) 0.9. When the Model J receiver evaluates equation 16b using the scaling factor value of 0.9 received from the Model I transmitter, the Model J receiver has a somewhat reduced P (due to the presence of the Model I transmitter, which is known to induce less receiver coil loss than the reference radiopower transmitter). LOSSRX To accurately estimate the value of P, by using the scaling factor received from the Model I transmitter, receiver J can be estimated to be P LOSSRXThe magnetic loss parameters used to calculate can be appropriately scaled to reflect the fact that the Model I transmitter is present in place of the reference radio-power transmitter, thereby P LOSSRX This can improve the accuracy of estimating the value of [the variable].

[0112] During the operation of block 1306, the Model I transmitter measures the transmitter coil current I TX Measurement value, b R and R AIRTX The known value of, as well as the scaling coefficient g received from the radio power receiver during the evaluation in Equation 15b. b Using P LOSSTX The scaling factor g can be estimated. b This reflects how the Model J receiver is expected to affect the transmitter coil losses in a transmitter paired with the Model J receiver instead of a reference radio power receiver. For example, the Model J receiver may tend to cause the paired transmitter to have higher transmitter coil losses than the reference radio power receiver. As a result, the scaling factor g received by the Model I transmitter from the Model J receiver... b The value of can be 1.1 (for example). When evaluating equation 15b, the increased scaling factor helps explain the fact that transmitter I should expect greater transmitter coil losses than when it is coupled to a model J receiver and therefore to a reference radiopower receiver.

[0113] During the operation of block 1307, P calculated in block 1304 LOSSRX The value can be transmitted to the paired transmitter. During the operation of block 1308, the radio power transmission system 8 (e.g., radio power transmitter 12 and / or associated control circuit 16) uses formula 14 to transmit P FO The value of can be evaluated (for example, if there is foreign matter power loss, foreign matter power loss can be estimated). Using the scaling factor information received from the Model J receiver, P LOSSTX To accurately estimate and from the Model J receiver P LOSSRXBy receiving the estimated value of P, the Model I transmitter calculates P for Equation 14. LOSSTX and P LOSSRX It can have both. IN The value of is determined by the wireless power transmitter, which is the transmitter coil current (I TX ) can be obtained by calculating the product of the voltage from the measurement circuit 41. OUT The value of is determined by the receiver coil current I, transmitted by the wireless power transmitter. RX By calculating the product of the rectifier output voltage received from the measurement circuit 43, or by receiving P from the wireless power receiver OUT It can be obtained by receiving it.

[0114] During the operation of block 1308, P FO After determining the value of P, the transmitter will FO This can be compared with the threshold power loss value (TH). Next, the wireless power transmission system 8 can take a suitable action. For example, P FO Based on the determination that it is less than TH, it can be concluded that no foreign matter is present and that the power transmission operation can proceed normally (for example, so that power can be transmitted and the battery 58 can be charged). FODepending on whether it is determined that is greater than TH, power transmission operations may be restricted. Examples of power transmission restrictions that may be implemented include stopping all power transmission operations (i.e., suppressing wireless power transmission) and / or stopping power transmission if it is already in progress, limiting the maximum amount of power that can be transmitted (e.g., to a relatively low predetermined power level below the normal maximum power transmission capacity of the wireless power transmission system), and / or issuing visual, auditory, and / or vibrational alerts to the user. If desired, alerts to the user (e.g., warnings and / or other informational content informing the user that a foreign object has been detected and power transmission operations are not proceeding normally) may be presented using output devices in the wireless power transmitter 12 and / or wireless power receiver 24. For example, a control circuit in the wireless power transmitter 12 may communicate wirelessly with a control circuit in the wireless power receiver 24 to issue a visual alert that is presented on a display in the wireless power receiver 24.

[0115] The exchange of scaling parameters between various wireless power transmission devices, as described above, can be considered to provide "ecosystem scaling" in the sense that it expands the "ecosystem" of devices that can cooperate to provide wireless power transmission and foreign object detection. Such ecosystem scaling can be extended to the context of combined Q foreign object detection, as described above.

[0116] The basic procedure for performing ecosystem scaling of combination Q involves four steps 1431–1434 shown in Figure 14. (As used herein, “step” simply refers to each operation performed, and is not intended to invoke a “step plus function” interpretation of any claim referring to an element of steps 1431–1434 unless the phrase “step for xyz” is expressly used in such a claim). Steps 1431–1433 involve the extraction of a new coefficient. In step 1 (1431), a promising (reference) radio power transmitter (indicated as GTx) may be coupled with a promising (reference) radio power receiver (indicated as GRx), and the combination Q threshold (e.g., line 901 in Figure 9) may be extracted as follows:

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[0117] In step 3(1433), a new radio power receiver (indicated as PRx) may be combined with GTx, and the threshold may be extracted as follows:

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[0118] Step 4 (1434): Up to this point, both the new PTx and PRx have a set of coefficients within their respective firmware. Threshold coefficient A 0,tg , A 1,tg , A 2,tg The values ​​are stored in PTx, and the scaling factors g0, g1, and g2 are stored in PRx. When PTx and PRx match within the field, the new detection threshold can be defined as follows:

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[0119] As described above, combined Q technology can be used to detect foreign objects (FOs) in the vicinity of a radio power transmission system (including a radio power transmitter and a radio power receiver). Physical quantities, such as the resonant frequency (f), quality factor (Q), and coupling coefficient (K) of the combined system (PTx coupled to PRx), can be measured using a low-power ping (LPP), as described above with respect to Figure 7, for example. Foreign objects can be detected in the fQ space, i.e., the space having the resonant frequency on one axis and the quality factor on another axis. One technique may be to use a linear threshold to separate the two classes: no FO (Rx only, or Rx with or without a case) and with FO (both with and without a case or cover). (As described herein, “case,” “cover,” and “case / cover” refer to an object associated with a PRx device, for example, as a case or cover used in connection with a mobile phone. A linear classifier can be trained using a given dataset with a linear support vector machine (SVM) to obtain thresholds. Other classifier implementations may also be used, and the trained classifier may potentially be implemented using the hardware described above with respect to Figure 1, along with suitable software to run on that hardware. However, due to the non-linear alignment of clusters formed by PRx at different locations (characterized by R and z), the linear classifier may not be ideal in some scenarios. Using multiple linear thresholds, a more effective separation known as the split thresholding method can be produced, as shown in Figure 15.)

[0120] More specifically, Figure 15 shows various clusters of frequency deviation versus Q deviation measurements. Parameters other than frequency deviation and Q deviation can be used, and therefore the axes can correspond to various functions of f and Q, as introduced above with respect to Figure 9. Such modifications are described in more detail below. Nevertheless, in the example of Figure 15, clusters 1505a to 1505f correspond to different scenarios or configurations where only receivers are present. Clusters 1503a and 1503c correspond to different scenarios or configurations where foreign objects are present. Curves 1501a to 1501b show multiple linear threshold curves as described in the previous paragraph. These generally correspond to the configurations described above with reference to Figure 9.

[0121] One potential drawback of multi-threshold systems may be the increased number of parameters required to describe the partition thresholds (one or more). Nonlinear separation can also present challenges to ecosystem scaling (e.g., because thresholds may depend on the training state space). To address these challenges, the technique described below, based on a reduced state space (Rx only, i.e., no foreign objects), can be used while improving classification accuracy. This technique can utilize mapping physical quantities: resonant frequency f, quality coefficient Q, and coupling coefficient K, to different spaces where Rx-only clusters naturally align with each other. The parameters of the line (representing Rx-only clusters) can be calculated by linear regression. When foreign objects are coupled to the combinational system, the data deviates from this line and can therefore be detected. The clear separation of the four categories: Rx only, Rx + case / cover, Rx + FO, and Rx + FO + case / cover can be demonstrated by taking the distance to its line. Since the classifier does not require training with foreign object data, it can function for any foreign object (ferrous and non-ferrous) as long as separation is present when the foreign object is placed within the detection limit (e.g., within 23-24 mm in some applications).

[0122] To map the physical quantities f, Q, and K to new observables that exhibit linear dependence, it is necessary to model the theoretical correlations between them. The combined resonant frequency is determined by the imaginary input impedance Im(Z) from Tx. in The input impedance is given by the condition that ) = 0. The input impedance is the impedance of Tx, Z Tx and reflection impedance from Rx, Z ref This is given by the following:

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[0123] To simplify the calculation, we can set ω to the range of 10 to the power of 6, and C tot We can set L to the range of 10 to the power of -9. M We can set the range to 10 to the power of -5, and R M , R Rx We observe that this can be in the range of 10 to the power of 0. Then, the imaginary part of the input impedance can be simplified as follows.

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[0124] ω 組み合わせ and ω Tx The ratio can be found as follows:

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[0125] Next, the combined inductance L 組み合わせ We define it as follows:

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[0126] Furthermore, the quality coefficients for the combinational system are as follows:

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[0127] As mentioned above, due to linear dependence, in order to transform the fQK space for foreign object detection, f 2 組み合わせ , 1 / (f 組み合わせ Q 組み合わせ ), and K 2 You can choose this. In practice, to reduce the effects of inter-part variations, f 2 def , 1 / (fdef Q def ), K 2 We use this as our observable, and here,

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[0128] In equations (49) to (51), "meas" represents the quantity measured at runtime (based on the actual Tx-to-Rx coupling), and "cal" represents the calibration of the Tx module in the factory / manufacturing (this value can be stored in the transmitter device's memory as described above). Using such calibration can reduce the impact of component-to-component variations due to manufacturing tolerances, etc.

[0129] Referring to plot 1600a in Figure 16A, by fitting clusters 1605a to 1605e of Rx only using linear regression (line 1601), the L2 distances to the line in the transformed fQK space for various measurement points in the other clusters 1603a to 1603c (foreign matter), 1607a to 1607b (receiver and case / cover), and 1609a to 1609b (receiver, case / cover, and foreign matter) can indicate the presence of receiver only, receiver and case / cover, receiver and foreign matter, or receiver, case / cover, and foreign matter. (Note that cluster 1603b, corresponding to measurements associated with the presence of the receiver and foreign matter, and cluster 1609a, corresponding to measurements associated with the presence of the receiver, case / cover, and foreign matter, overlap in the illustrated example, but this is not the case in all cases. As shown in the histogram plot 1600b in Figure 16B, the categories Rx only (1605), Rx + case / cover (1607), Rx + FO (1603), and Rx + FO + case / cover (1609) can be separated based on the L2 distance from the regression line 1601. In the illustrated example, the L2 distance is A threshold of 0.125 can be used to effectively separate non-foreign cases from foreign cases. In the illustrated example, there is an overlap between the case / cover absence measurement and the case / cover presence measurement, but this does not affect the determination of whether a foreign object is present or not. In addition, the specific thresholds given above are illustrative only. Different thresholds may be required depending on the specific physical characteristics and configuration of a given implementation. This threshold (or any appropriate threshold based on the details of a given application) can be programmed into a classifier implemented using any appropriate combination of hardware and software as described above.

[0130] Such a classifier can have at least two advantages: (1) It does not require training with FO data. Once the distribution of the first two categories (Rx only 1605 and Rx + case / cover 1607) is determined, the foreign object detection threshold can be set by the maximum distance to the line. Anything exceeding the threshold is considered along with the FO. Thus, this technique can be performed for any type of FO. (2) Such a classifier may be unaffected by the state space. Since the clusters within the Rx only category (1605a 1605e) are aligned, the linear regression will converge to a fixed value as long as the state space is sufficiently large.

[0131] In practice, each cluster can have some volume within the transformed fQK space. As the FO radius (defined as the distance between the FO center and the Tx center) increases, the latter two categories (Rx + FO and Rx + FO + case / cover) can eventually intersect with the first two categories (Rx only and Rx + case / cover). The maximum FO radius at which there is no intersection can be defined as the detection limit. In exemplary embodiments, the detection limit may be 23 mm to 24 mm. Note that the detection limit is not the same as the critical radius. The detection limit is the FO distance at which FO can be reliably detected. The critical radius is given by the acceptable range of FO temperature rise and therefore increases with the power level delivered. Therefore, it may be preferable for the detection limit to be greater than the critical radius.

[0132] The measurement of the distance between data points and a linear regression line can be optimized to increase the margin between the foreign object category and the foreign object-free category. Specifically, as shown in plot 1700a in Figure 17A, for measurement, the L1 distance, i.e., the sum of the distances to the regression line 1701 in the x, y, and z directions, or the L2 distance, i.e., the distance closest to the line, can be selected. These distances are illustrative, and other distance measurements can also be used. As shown in histogram plot 1700b in Figure 17B, the L2 distance may provide little margin between the foreign object case and the foreign object-free case (for the illustrative system shown). Conversely, as shown in histogram plot 1700c in Figure 17C and histogram plot 1700d in Figure 17D, corresponding to the L1 distance, the L1 distance can provide a better margin.

[0133] The remapped state space (e.g., the one described above (e.g., f2, 1 / (fQ), K state space) can also be used in conjunction with the ecosystem scaling principle described above, with reference to Figures 12-14. Such use of ecosystem scaling is described in more detail below with reference to Figures 18A-18C. For any one Tx-Rx pair, whether promising or general, the Rx-only clusters 1805a, 1805f are always aligned in the transformed fQK space 1800a. For simplicity, the transformed observables can be renamed x, y, and z. The linear equation that aligns the Rx-only clusters 1805a, 1805f can be written as follows:

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[0134] As shown in Figures 18A and 18C, the exemplary scaled fit 1801b is very similar to the calculated line given by linear regression on the dataset (1801a). Thus, as can be seen from the comparison between Figures 18B and 18C, the histogram 1800c for the scaled fit 1801b (Figure 18A) is close to the histogram 1800b associated with the actual line 1801a (Figure 18A). The accuracy of the scaled fit means that an appropriate level of foreign object detection accuracy can be expected when using the ecosystem scaling principle described below. In fact, in many cases, the threshold does not need to be changed.

[0135] In at least some applications, the combined Q measurement described herein can provide not only information about the presence of a foreign object, but also information about the location of the foreign object. Such information is given P rect and V rect It can be used to estimate the potential foreign object loss relative to the value. Also, as mentioned above, the foreign object position can affect the separation between the measured data points and the linear regression fit.

[0136] As shown in plot 1900 of Figure 19, the L2 distance (vertical axis) between the data point and the linear regression line decreases with the FO radius, i.e., the distance to the foreign object. This applies to each group of measurements, namely, receiver-only measurements shown in curve 1905, receiver + case / cover measurements shown in curve 1907, receiver and foreign object measurements shown in curve 1903, and receiver + case / cover + foreign object measurements shown in curve 1909. The error bars represent the standard deviation for each category. Since the FO radius is directly related to FO loss, the distance can be used to adjust the transmitter output power level accordingly. The table below lists exemplary estimates of FO radii at which the power dissipated within the foreign object reaches 800 mW, which is in the range of 20 mm to 30 mm. The first column of the table lists exemplary power levels (for each row). The second column lists the estimated FO radii with Tx and Rx coupled with a radial offset of 0 and a z-axis / vertical offset of 2 mm, and the third column lists the estimated FO radii with Tx and Rx coupled with a radial offset of 2 mm and a z-axis / vertical offset of 2.2 mm. [Table 1]

[0137] By combining the L2 distance vs. RFO relationship and the FO loss vs. RFO relationship, an acceptable power level can be estimated as a function of the L2 distance. Thus, instead of completely shutting down power transmission when a foreign object is detected, a multi-level power adjustment strategy can be employed. An example of such multi-level power level adaptation is shown in FIG. 20, where (1) when the L2 distance is within 0.12, full power (e.g., a power level of 50 W) can be delivered, (2) when the L2 distance is between 0.12 and 0.22, the power should be adjusted to a first intermediate power level (e.g., 25 W), (3) when the distance is between 0.22 and 0.35, the power should be adjusted to a second intermediate power level (e.g., 15 W), and (4) otherwise, when the L2 distance is greater than 0.35, the power should be adjusted to a low power level (e.g., 5 W). These power levels are exemplary and may be useful in various embodiments, but the specific L2 distances and power levels can be adapted as appropriate for a given application.

[0138] As described above, FIG. 20 shows various power levels by concentric cylinders centered on a fit line passing through the Rx-only data point 2005. The receiver + case / cover data point 2007 is also shown. The inner cylinder 2010 corresponds to the highest power level (e.g., 50 W) described above. The next cylinder 2011 corresponds to the first intermediate power level (e.g., 25 W). The next cylinder 2012 corresponds to the second intermediate power level (e.g., 15 W). The outer cylinder 2013 corresponds to the low power level (e.g., 5 W). As explained above, if the measured operating point has an L2 distance from the linear regression fit line 2001 that exceeds the above exemplary thresholds, the transmitted power can be limited to the specified (and corresponding to the concentric cylinders) levels.

[0139] In other embodiments, whether separate from or combined with the features of the above-described embodiments, a combined Q measurement state space (including but not limited to any of the above-described magnetic parameters) can be used to detect the presence of other similar devices that surround or protect a case, cover, or wireless power receiver, and thus provide a certain degree of z-axis separation between the wireless power transmitter (PTx) and the wireless power receiver (PRx). In this context, the z-axis refers to the direction perpendicular to the plane of each coil. In such cases, the measurement and determination of various circuit parameters can be performed according to any suitable technique including the techniques described above. The resulting group of data points can be plotted in the state space based on the parameters measured as described above.

[0140] FIG. 21 shows an exemplary state space plot 2100. The illustrated state space is based on the changes in the quality factor (Q) and the resonance frequency (f) plotted on the vertical and horizontal axes respectively. However, any suitable state space using a combination of other parameters such as the linearized parameters described above can also be used. FIG. 21 also shows data points 2105a - 2105f corresponding to the combined Q measurement values of only the receiver device. As described above, these combined Q measurement values can include any combination of the above-described parameters that can be directly measured and / or calculated by the processing system based on the measured parameters. Each of the clusters 2105a - 2105f corresponds to a different distance between the receiver and the transmitter, and in the illustrated example, they are 0 mm, 1 mm, 2 mm, 2.2 mm, 3 mm, and 3.2 mm respectively. Also, FIG. 21 shows data points 2107a, 2107d corresponding to a receiver having a case or other cover or protective device intervening between the wireless power transmitter (PTx) and the wireless power receiver (PRx).

[0141] Similar to the techniques described above, a threshold can be calculated by the system, allowing the system to detect z-axis / vertical separation between the radio power transmitter and radio power receiver, such as separation caused by the presence of a case, cover, or other similar object. However, such separation does not necessarily have to be caused by the presence of an additional object. In any case, the detection of such z-axis / vertical separation can be used by the PTx device to reduce power and mitigate electromagnetic interference with other devices. The process may be largely the same as described above with respect to Figure 10, except that instead of detecting foreign objects, what is being detected is the presence of a case or cover and / or z-axis / vertical separation between the PTx and PRx.

[0142] To achieve such detection, the threshold can be defined by curve 2101. Curve 2101 may also be a linear function of the following form:

number

number

[0143] The slope of threshold line 2101 may be observed to be negative with respect to the slope of the foreign object detection line given in the example above. Therefore, when performing both foreign object detection and z-axis / vertical separation / case detection, separate thresholds may be used for each detection, but both detections (and their associated regressions or other statistical analyses) may be based on the same measured values / data points. In the example shown with respect to Figure 1, the determination is whether there is z-axis / vertical separation between PRx and PTx, as opposed to whether a foreign object is present as described above with reference to Figures 9-10. In other respects, the measurements, analyses, decisions etc. performed by the processing systems of each device may be broadly similar.

[0144] Additional items: 1. A wireless power transmitter, A wireless power transmitting circuit having a wireless power transmitting coil that transmits wireless power signals, The circuit comprises a control circuit coupled to a wireless power transmission circuit, and the control circuit is While the wireless power transmitter is coupled to the wireless power receiver, the current values ​​of a first function of the quality coefficient and resonant frequency of the wireless power transmitting coil and the current values ​​of a second function of the quality coefficient and resonant frequency of the wireless power transmitting coil are measured. Determine the change between the measured current values ​​and the corresponding baseline values ​​of the first and second functions of the quality coefficient and resonant frequency of the wireless power transmitting coil. A wireless power transmitter that determines whether foreign matter is present based on the change between the measured current values ​​of a first function and a second function of the quality factor and resonant frequency, and the corresponding baseline value in the magnetic state space above a threshold. 2. The control circuit suppresses wireless power transmission in response to the detection of a foreign object, as described in item 1, for the wireless power transmitter. 3. The control circuit is a wireless power transmitter as described in item 1, which transmits power at a level below the maximum power level in response to the detection of a foreign object. 4. The control circuit determines the current quality factor and resonant frequency of the wireless power transmission coil. The inverter provides one or more signal pulses to the wireless power transmission coil, Using a measurement circuit, measure the response to one or more provided signal pulses, wherein the response includes a ringing signal having an attenuation envelope characterized by the frequency of the ringing signal and the current quality factor. A wireless power transmitter as described in item 1, which measures the current quality factor and resonant frequency from the ringing signal frequency. 5. The control circuit is, Based on the change between the measured current values ​​of the quality coefficient and the first and second functions of the resonant frequency of the wireless power transmitting coil and the corresponding baseline values, the foreign matter is characterized as moderate or strong foreign matter. Depending on whether the foreign object is determined to be a strong foreign object, wireless power transmission may be suppressed, or A wireless power transmitter as described in item 1, which enables wireless power transmission at a relatively lower power level depending on whether the foreign object is determined to be a moderate foreign object. 6. The corresponding baseline value is measured during the manufacture of the radio power transmitter as described in item 1. 7. The corresponding baseline value is updated during field operation of the wireless power transmitter as described in item 1. 8. The control circuit determines the change between the measured current values ​​of the quality coefficient and the first and second functions of the resonant frequency of the radio power transmitting coil, using a scale factor based on a specific transmitter-receiver pairing, as described in item 1 of the radio power transmitter. 9. A method for operating a wireless power transmitter having a wireless power transmitting circuit including a wireless power transmitting coil configured to transmit a wireless power signal, and a control circuit coupled to the wireless power transmitting circuit, the method being performed by the control circuit, While the wireless power transmitter is coupled to the wireless power receiver, the current values ​​of a first function of the quality coefficient and resonant frequency of the wireless power transmitting coil, and the current values ​​of a second function of the quality coefficient and resonant frequency of the wireless power transmitting coil are measured. The measured current values ​​of the quality factor and the first and second functions of the resonant frequency of the wireless power transmission coil are compared with the corresponding baseline values. Detecting foreign matter, at least in part, based on a comparison between the measured current values ​​of the first and second functions of the quality factor and resonant frequency and the corresponding baseline values, Methods that include... 10. Comparison of the measured current values ​​of the quality coefficient and the first and second functions of the resonant frequency of the wireless power transmitting coil with the corresponding baseline values ​​includes analyzing the change between the measured current values ​​and the corresponding baseline values ​​in magnetic state space. The method according to item 9, wherein detecting foreign matter, at least in part, based on a comparison of measured current values ​​of first and second functions of the quality factor and resonant frequency with corresponding baseline values, includes determining whether the change between the measured current value and the corresponding baseline value in magnetic state space exceeds a threshold. 11. The current quality factor and resonant frequency of the wireless power transmitting coil are as follows: The inverter provides one or more signal pulses to the wireless power transmission coil, Using a measurement circuit, measure the response to one or more provided signal pulses, wherein the response includes a ringing signal having an attenuation envelope characterized by the frequency of the ringing signal and the current quality factor. The method according to item 9, further comprising determining the current quality factor from the frequency of the ringing signal and measuring it by... 12. The method according to item 9, further comprising suppressing wireless power transmission in response to detecting a foreign object. 13. The method according to item 9, further comprising transmitting power at a level below the maximum power level in response to detecting a foreign object. 14. Characterizing a foreign object as a medium foreign object or a strong foreign object based on a change between a measured current value and a corresponding baseline value in a magnetic state space, suppressing wireless power transmission in response to determining that the foreign object is a strong foreign object, or enabling wireless power transmission at a relatively lower power level in response to determining that the foreign object is a medium foreign object, the method according to item 9. 15. The method according to item 9, wherein the corresponding baseline value is measured during the manufacture of the wireless power transmitter. 16. The method according to item 9, wherein the corresponding baseline value is updated during the field operation of the wireless power transmitter. 17. The method according to item 9, further comprising scaling the corresponding baseline value using a scale factor based on a specific transmitter-receiver pairing. 18. A wireless power transmitter, a wireless power transmission circuit having a wireless power transmission coil for transmitting a wireless power signal, a control circuit coupled to the wireless power transmission circuit, the control circuit comprising means for measuring current values of two or more observables related to the quality factor and resonance frequency of the wireless power transmission coil while the wireless power transmitter is coupled to a wireless power receiver, means for detecting a foreign object based on the measured current values of two or more observables related to the quality factor and resonance frequency of the wireless power transmission coil measured while the wireless power transmitter is coupled to a wireless power receiver, the wireless power transmitter. 19. The control circuit The control circuit further comprises means for characterizing a foreign object as a moderate or strong foreign object based on the measured current values ​​of two or more observed quantities relating to the quality coefficient and resonant frequency of the radio power transmitting coil, measured while the radio power transmitter is coupled to the radio power receiver, Depending on whether the foreign object is determined to be a strong foreign object, wireless power transmission may be suppressed, or A wireless power transmitter as described in item 18, which enables wireless power transmission at a relatively lower power level depending on whether the foreign object is determined to be a moderate foreign object.

[0145] Further additions: 1. A wireless power transmitter, A wireless power transmitting circuit having a wireless power transmitting coil that transmits wireless power signals, The circuit comprises a control circuit coupled to a wireless power transmission circuit, and the control circuit is While the wireless power transmitter is coupled to the wireless power receiver, the current values ​​of a first function of the quality coefficient and resonant frequency of the wireless power transmitting coil and the current values ​​of a second function of the quality coefficient and resonant frequency of the wireless power transmitting coil are measured. Determine the change between the measured current values ​​and the corresponding baseline values ​​of the first and second functions of the quality coefficient and resonant frequency of the wireless power transmitting coil. A radio power transmitter that determines the z-axis separation distance between the radio power transmitter and the radio power receiver based on the change between the measured current values ​​of the quality coefficient and the first and second functions of the resonant frequency and the corresponding baseline value that exceeds a threshold in magnetic state space. 2. The z-axis separation distance is the same as that of the radio power transmitter as described in item 1, including the presence of a case or cover on the radio power receiver. 3. The first function of the quality factor and the resonant frequency is the quality factor, The second function of the quality factor and the resonant frequency is the resonant frequency. The threshold is a wireless power transmitter as described in item 1, including multiple linear thresholds. 4. A wireless power transmitter, A wireless power transmitting circuit having a wireless power transmitting coil that transmits wireless power signals, The circuit comprises a control circuit coupled to a wireless power transmission circuit, and the control circuit is While the wireless power transmitter is coupled to the wireless power receiver, the current values ​​of a first function of the quality coefficient and resonant frequency of the wireless power transmitting coil, the current values ​​of a second function of the quality coefficient and resonant frequency of the wireless power transmitting coil, and a third function of the quality coefficient and resonant frequency of the wireless power transmitting coil are measured. The distance between the measured current values ​​of the first, second, and third functions of the quality coefficient and resonant frequency of the wireless power transmitting coil and the curve fitting to the corresponding baseline values ​​in magnetic state space is determined. A radio power transmitter that determines the z-axis separation distance between the radio power transmitter and the radio power receiver, depending on the distance between the measured current values ​​of the first, second, and third functions of the quality coefficient and resonant frequency and the curve fitting to the corresponding baseline values ​​in the magnetic state space above a threshold. 5. The z-axis separation distance is the same as that of the radio power transmitter as described in item 4, including the presence of a case or cover on the radio power receiver. 6. The first, second, and third functions of the quality factor and resonant frequency are selected to provide a linear curve fit in magnetic state space, as described in item 4, for the radio power transmitter. 7. A wireless power transmitter as described in item 6, wherein the first function of the quality factor and resonant frequency is the square of the coupling coefficient, the second function of the quality factor and resonant frequency is the square of the resonant frequency, and the third function of the quality factor and resonant frequency is the reciprocal of the product of the resonant frequency and the quality factor. 8. The distance is the Pythagorean distance, as described in item 4 for the wireless power transmitter. 9. The distance is L1 distance, as described in item 4 for the wireless power transmitter. 10. The distance is L2 distance, as described in item 4 for the wireless power transmitter. 11. The control circuit transmits power at a level below the maximum power level in response to the detection of a z-axis separation distance or the presence of a case that exceeds a threshold, as described in item 4 of the wireless power transmitter. 12. The control circuit determines the current quality factor and resonant frequency of the wireless power transmission coil. The inverter provides one or more signal pulses to the wireless power transmission coil, Using a measurement circuit, measure the response to one or more provided signal pulses, wherein the response includes a ringing signal having an attenuation envelope characterized by the frequency of the ringing signal and the current quality factor. A radio power transmitter as described in item 4, which measures the current quality factor and resonant frequency from the ringing signal frequency. 13. The corresponding baseline value is measured during the manufacture of the radio power transmitter as described in item 4. 14. The corresponding baseline value is updated during field operation of the wireless power transmitter as described in item 4. 15. The control circuit determines the distance between the measured current values ​​of the first, second, and third functions of the quality coefficient and resonant frequency of the radio power transmitting coil, using a scale factor based on a specific transmitter-receiver pairing, as described in item 4 of the radio power transmitter. 16. A method for operating a wireless power transmitter having a wireless power transmitting circuit including a wireless power transmitting coil configured to transmit a wireless power signal, and a control circuit coupled to the wireless power transmitting circuit, the method being performed by the control circuit, While the wireless power transmitter is coupled to the wireless power receiver, the current values ​​of a first function of the quality coefficient and resonant frequency of the wireless power transmitting coil, and the current values ​​of a second function of the quality coefficient and resonant frequency of the wireless power transmitting coil are measured. The measured current values ​​of the quality factor and the first and second functions of the resonant frequency of the wireless power transmission coil are compared with the corresponding baseline values. The z-axis separation distance between the radio power transmitter and the radio power receiver is determined, at least in part, based on a comparison of the measured current values ​​of the first and second functions of the quality factor and resonant frequency with the corresponding baseline values. including, method. 17. The z-axis separation distance is determined by the method described in item 16, including the presence of a case or cover on the radio power receiver. 18. The first function of the quality factor and the resonant frequency is the quality factor, The method described in item 16, wherein the second function of the quality factor and the resonant frequency is the resonant frequency. 19. A method for operating a wireless power transmitter having a wireless power transmitting circuit including a wireless power transmitting coil configured to transmit a wireless power signal, and a control circuit coupled to the wireless power transmitting circuit, the method being performed by the control circuit, While the wireless power transmitter is coupled to the wireless power receiver, the current values ​​of a first function of the quality coefficient and resonant frequency of the wireless power transmitting coil, the current values ​​of a second function of the quality coefficient and resonant frequency of the wireless power transmitting coil, and the current values ​​of a third function of the quality coefficient and resonant frequency of the wireless power transmitting coil are measured. This involves comparing the measured current values ​​of the first, second, and third functions of the quality coefficient and resonant frequency of a wireless power transmitting coil with the corresponding baseline values ​​by determining the distance between these values ​​and the curve fitting to the corresponding baseline values ​​in magnetic state space. Determining the z-axis separation distance between a radio power transmitter and a radio power receiver based at least partially on the distance between the measured current values ​​of the first, second, and third functions of the quality factor and the resonant frequency, and the curve fitting to the corresponding baseline value in the magnetic state space above the threshold, Methods that include... 20. The z-axis separation distance is determined by the method described in item 19, including the presence of a case or cover on the radio power receiver. 21. The method according to item 19, wherein the first, second, and third functions of the quality factor and resonant frequency are selected to provide a linear curve fit in magnetic state space. 22. The method according to item 21, wherein the first function of the quality factor and the resonant frequency is the square of the coupling coefficient, the second function of the quality factor and the resonant frequency is the square of the resonant frequency, and the third function of the quality factor and the resonant frequency is the reciprocal of the product of the resonant frequency and the quality factor. 23. The distance is the Pythagorean distance, as described in item 19. 24. The distance is the L1 distance, as described in item 19. 25. The distance is the L2 distance, as described in item 19. 26. The current quality factor and resonant frequency of the wireless power transmitting coil are as follows: The inverter provides one or more signal pulses to the wireless power transmission coil, Using a measurement circuit, measure the response to one or more provided signal pulses, wherein the response includes a ringing signal having an attenuation envelope characterized by the frequency of the ringing signal and the current quality factor. The method of item 19, further comprising determining the current quality factor from the frequency of the ringing signal and measuring it by... 27. The method according to item 19, further comprising transmitting power at a level below the maximum power level in response to the detection of a z-axis separation distance or the presence of a case exceeding a threshold. 28. The corresponding baseline value is measured during the manufacture of the radio power transmitter, as described in item 19. 29. The corresponding baseline value is updated during field operation of the wireless power transmitter, as described in item 19. 30. The method according to item 19, further comprising scaling the corresponding baseline value using a scaling factor based on a specific transmitter-receiver pairing.

[0146] Various features and embodiments relating to the use of combined Q-factors and associated magnetic property measurements for object detection in wireless power transmission systems have been described above. Such configurations can be used in a variety of applications, but may be particularly advantageous when used with electronic devices such as mobile phones, tablet computers, laptops or notebook computers, and accessories such as wireless headphones and styluses. In addition, while numerous specific features and various embodiments have been described, it should be understood that various features and embodiments can be combined in various permutations in a particular implementation unless otherwise specifically stated to be mutually exclusive. Therefore, the various embodiments described above are provided for illustrative purposes only and should not be construed as constituting the scope of this disclosure. Various modifications and changes can be made to the principles and embodiments herein without departing from the scope of this disclosure or the claims.

Claims

1. A wireless power transmitter, A wireless power transmitting circuit having a wireless power transmitting coil that transmits wireless power signals, The wireless power transmission circuit comprises a control circuit coupled to the aforementioned wireless power transmission circuit, and the control circuit is While the wireless power transmitter is coupled to the wireless power receiver, the current value of a first function of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil, and the current value of a second function of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil are determined. The determined current values ​​of the first and second functions of one or both of the quality coefficient and the resonant frequency of the wireless power transmitting coil are compared with the curve fitting to the corresponding baseline values ​​in a magnetic state space having axes defined by the first and second functions of one or both of the quality coefficient and the resonant frequency. If the determined current values ​​of the first and second functions of one or both of the quality coefficient and the resonant frequency are on the first side of the curve, it is determined that no foreign matter is present, or If the determined current values ​​of the first and second functions of one or both of the quality coefficient and the resonant frequency are on the second side of the curve and different from the first side of the curve, then it is determined that foreign matter is present. The control circuit, upon determining the presence of the foreign object, either suppresses wireless power transmission or transmits power at a level below the maximum power level. One of the first function or the second function of either or both of the quality coefficient and the resonant frequency is the reciprocal of the product of the resonant frequency deviation and the quality coefficient deviation. The aforementioned resonant frequency deviation is the ratio of the value of the resonant frequency of the wireless power transmitting coil measured while the wireless power transmitter is coupled to the wireless power receiver, to the calibration value of the resonant frequency. The quality factor deviation is the ratio between the value of the quality factor of the wireless power transmitting coil measured while the wireless power transmitter is coupled to the wireless power receiver, and the calibration value of the quality factor. Wireless power transmitter.

2. The wireless power transmitter according to claim 1, wherein the first and second functions of one or both of the quality coefficient and the resonant frequency are selected to provide a linear curve fit in the magnetic state space.

3. The control circuit determines the current quality coefficient and resonant frequency of the wireless power transmitting coil. The inverter is made to provide one or more signal pulses to the wireless power transmission coil, Using a measurement circuit, measure the response to one or more signal pulses provided, wherein the response includes the ringing signal having an attenuation envelope characterized by the frequency of the ringing signal and the current quality factor. The wireless power transmitter according to claim 1, which measures the current quality coefficient and resonant frequency by determining them from the frequency of the ringing signal.

4. The aforementioned control circuit is Based on the distance between the determined current values ​​of the first and second functions of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil and the curve fitting to the corresponding baseline value, the foreign matter is characterized as moderate or strong foreign matter. In response to determining that the foreign object is a strong foreign object, wireless power transmission is suppressed, or The wireless power transmitter according to claim 1, which enables wireless power transmission at a relatively lower power level in response to the determination that the foreign matter is a moderate foreign matter.

5. The wireless power transmitter according to claim 4, wherein the distance is L1 distance, which is the sum of the respective distances between the determined current values ​​of the first and second functions of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil and the axis defined by the first and second functions of one or both of the quality coefficient and resonant frequency.

6. The wireless power transmitter according to claim 4, wherein the distance is L2 distance, which is the closest distance between the determined current values ​​of the first and second functions of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil and the axis defined by the first and second functions of one or both of the quality coefficient and resonant frequency.

7. The wireless power transmitter according to claim 1, wherein the corresponding baseline value is measured during the manufacture of the wireless power transmitter.

8. The wireless power transmitter according to claim 1, wherein the corresponding baseline value is updated during the field operation of the wireless power transmitter.

9. The wireless power transmitter according to claim 1, wherein the control circuit scales the baseline value using a scaling factor based on a specific transmitter-receiver pairing.

10. A method for operating a wireless power transmitter having a wireless power transmitting circuit including a wireless power transmitting coil configured to transmit a wireless power signal, and a control circuit coupled to the wireless power transmitting circuit, wherein the method is performed by the control circuit, While the wireless power transmitter is coupled to the wireless power receiver, the current value of a first function of one or both of the quality coefficient and the resonant frequency of the wireless power transmitting coil, and the current value of a second function of one or both of the quality coefficient and the resonant frequency of the wireless power transmitting coil are determined. Comparing the determined current values ​​of the first and second functions of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil with the curve fitting to the corresponding baseline values ​​in a magnetic state space having axes defined by the first and second functions of one or both of the quality coefficient and resonant frequency, If the determined current values ​​of the first and second functions of one or both of the quality coefficient and the resonant frequency are on the first side of the curve, then it is determined that no foreign matter is present, or If the determined current values ​​of the first and second functions of one or both of the quality coefficient and the resonant frequency are on the second side of the curve and different from the first side of the curve, then it is determined that foreign matter is present. In response to the determination that the aforementioned foreign object is present, wireless power transmission will be suppressed, or power will be transmitted at a level below the maximum power level. Includes, One of the first function or the second function of either or both of the quality coefficient and the resonant frequency is the reciprocal of the product of the resonant frequency deviation and the quality coefficient deviation. The aforementioned resonant frequency deviation is the ratio of the value of the resonant frequency of the wireless power transmitting coil measured while the wireless power transmitter is coupled to the wireless power receiver, to the calibration value of the resonant frequency. The quality factor deviation is the ratio between the value of the quality factor of the wireless power transmitting coil measured while the wireless power transmitter is coupled to the wireless power receiver, and the calibration value of the quality factor. ,method.

11. The method according to claim 10, wherein the first and second functions of one or both of the quality coefficient and the resonant frequency are selected to provide a linear curve fit in the magnetic state space.

12. The current quality coefficient and resonant frequency of the aforementioned wireless power transmitting coil are determined as follows: The inverter is made to provide one or more signal pulses to the wireless power transmission coil, Using a measurement circuit, measure the response to one or more signal pulses provided, wherein the response includes the ringing signal having an attenuation envelope characterized by the frequency of the ringing signal and the current quality factor. The method according to claim 10, further comprising determining the current quality factor from the frequency of the ringing signal and measuring it by:

13. Characterizing the foreign matter as moderate or strong based on the distance between the determined current value and the curve fitting to the corresponding baseline value in the magnetic state space, In response to determining that the aforementioned foreign object is a strong foreign object, wireless power transmission may be suppressed, or In response to the determination that the aforementioned foreign object is of moderate magnitude, it is possible to enable wireless power transmission at a relatively lower power level, The method according to claim 10, further comprising:

14. The method according to claim 13, wherein the distance is L1 distance, which is the sum of the distances between the determined current values ​​of the first and second functions of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil and the axis defined by the first and second functions of one or both of the quality coefficient and resonant frequency.

15. The method according to claim 13, wherein the distance is L2 distance, which is the closest distance between the determined current values ​​of the first and second functions of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil and the axis defined by the first and second functions of one or both of the quality coefficient and resonant frequency.

16. The method according to claim 10, wherein the corresponding baseline value is measured during the manufacture of the wireless power transmitter.

17. The method according to claim 10, wherein the corresponding baseline value is updated during the field operation of the wireless power transmitter.

18. The method according to claim 10, further comprising scaling the corresponding baseline value using a scaling factor based on a specific transmitter-receiver pairing.

19. The wireless power transmitter according to claim 1, wherein a first function of one or both of the quality coefficient and the resonant frequency is a frequency deviation, which is the difference between the determined resonant frequency of the wireless power transmitting coil and the baseline resonant frequency of the wireless power transmitting coil.

20. The wireless power transmitter according to claim 9, wherein the scaling factor is received from the wireless power receiver via the wireless power transmitting coil.

21. The method according to claim 10, wherein a first function of one or both of the quality coefficient and the resonant frequency is a frequency deviation, which is the difference between the determined resonant frequency of the wireless power transmitting coil and the baseline resonant frequency of the wireless power transmitting coil.

22. The method according to claim 18, wherein the scaling factor is received from the wireless power receiver via the wireless power transmitting coil.

23. A wireless power transmitting circuit having a wireless power transmitting coil for transmitting wireless power signals, and a control circuit coupled to the wireless power transmitting circuit, wherein the control circuit is A control circuit is configured to detect foreign matter by determining a point in a magnetic state space, the magnetic state space being defined by a first axis corresponding to a first function of one or both of the quality coefficient and the resonant frequency, and a second axis corresponding to a second function of one or both of the quality coefficient and the resonant frequency, wherein the control circuit is configured to detect foreign matter. The first coordinates of the point in the magnetic state space are calculated as the current value of a first function of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil, with the wireless power transmitter coupled to the wireless power receiver. The second coordinates of the point in the magnetic state space are calculated as the current value of a second function of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil, with the wireless power transmitter coupled to the wireless power receiver. The point in the magnetic state space is determined by comparing the determined point with a curve in the magnetic state space that is fitted to the corresponding baseline values ​​of the first and second functions of one or both of the quality coefficient and resonant frequency of the wireless power transmitting coil, thereby determining the presence of foreign matter. The control circuit determines that no foreign matter is present, depending on whether the determined point is on the first side of the curve. The control circuit determines that a foreign object is present if the determined point is on the second side of the curve, which is different from the first side of the curve. One of the first function or the second function of either or both of the quality coefficient and the resonant frequency is the reciprocal of the product of the resonant frequency deviation and the quality coefficient deviation. The aforementioned resonant frequency deviation is the ratio of the value of the resonant frequency of the wireless power transmitting coil measured while the wireless power transmitter is coupled to the wireless power receiver, to the calibration value of the resonant frequency. The quality factor deviation is the ratio between the value of the quality factor of the wireless power transmitting coil measured while the wireless power transmitter is coupled to the wireless power receiver, and the calibration value of the quality factor. Wireless power transmitter.

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