WIRELESS POWER SYSTEM WITH EXTERNAL OBJECT DETECTION

Abstract

Wireless power transmission device (12), comprising: a wireless power transmission circuit (52) configured to transmit wireless power signals to a wireless power receiving device (24); and Control circuit (16) configured to: Performing foreign object detection operations during a digital ping, including receiving measurements from the wireless power receiving device (24) during the digital ping; and In response to the determination during the digital ping that no foreign object is present based on the received measurements, cause a warning to be issued during the digital ping.

Description

[0001] This patent application claims priority over U.S. patent application No. 16 / 739,683, filed on January 10, 2020, and provisional patent application No. 62 / 886,614, filed on August 14, 2019, which are hereby incorporated in their entirety by reference herein. Area

[0002] This generally refers to power systems and, in particular, to wireless power systems for charging electronic devices. State of the art

[0003] In a wireless charging system, a wireless transmitter, such as a charging mat, wirelessly transmits power to a wireless charging receiver, such as a portable electronic device. The portable electronic device has a coil and a rectifier circuit. The coil of the portable electronic device receives wireless AC power signals from the wireless charging mat. The rectifier circuit converts the received signals into direct current.

[0004] US 2017 / 0331334A1 describes a method for detecting a foreign object on a wireless power transmission device and includes: periodically issuing ping signals to detect a wireless power receiving device; detecting the input current for the ping signals; comparing the detected input current to a predetermined current value; and if the detected input current for a plurality of ping signals exceeds the predetermined current value, determining that there is a foreign object on a surface of the wireless power transmission device.

[0005] US 2019 / 0190320A1 describes a method for detecting foreign material and a device and system for doing so, and a method for detecting foreign material in a wireless power transmitter includes: measuring a quality factor value corresponding to a reference operating frequency when an object is detected; searching for a current peak frequency with a maximum quality factor value within an operating frequency band; receiving, from a wireless power receiver, a foreign material detection status packet containing information about a reference peak frequency; correcting the measured quality factor value using a difference value between the current peak frequency and the reference peak frequency; and determining whether the foreign material is present by comparing the corrected quality factor value to a predetermined quality factor threshold. Brief description

[0006] The invention is described by the features of the dependent claims. Preferred advantageous embodiments thereof are described by the sub-features of the dependent claims.

[0007] A wireless charging system comprises a wireless power transmission device and a wireless power receiving device. The wireless power transmission device can be a wireless charging mat or any other device with a charging surface. The wireless power receiving device can be a portable electronic device that receives transmitted wireless power signals from the wireless power transmission device while resting on the charging surface.

[0008] After the wireless power receiving device is placed on the charging surface and before normal wireless power transmission begins, the wireless power transmitting device can perform digital ping operations. During digital ping operations, low-level wireless power signals can be transmitted from the wireless power transmitting device. Sufficient power is supplied to the power communication circuitry in the wireless power receiving device, but not enough to fully power the wireless power receiving device (e.g., to charge a battery in the wireless power receiving device).Information gathered during the digital ping, such as wireless power transfer efficiency, coupling coefficients, Q-factor, and coil inductance, can be used to determine if a foreign object is present on the charging surface near the wireless power transfer and receiver devices. The control circuitry in the wireless power transfer device can then cause the wireless power receiver to issue a warning to the user, indicating that wireless power transfer operations are about to begin after determining that no foreign object is present.The warning may occur during or immediately after the digital ping, before negotiations between the wireless power transmitting device and the wireless power receiving device are completed to establish suitable wireless power transmission levels that will be used during normal operation to charge a battery in the wireless power receiving device. Brief description of the drawings Fig. Figure 1 is a schematic diagram of an illustrative wireless power supply system according to one embodiment. Fig. Figure 2 is a flowchart illustrating the processes involved in operating a wireless power system according to one embodiment. Detailed description

[0009] A wireless power system includes a wireless power transmission device, such as a wireless charging pad. The wireless power transmission device wirelessly transmits power to one or more wireless power receiving devices. The wireless power receiving devices can include devices such as wristwatches, mobile phones, tablet computers, laptop computers, or other electronic devices. Each wireless power receiving device uses power from the wireless power transmission device to power the device and to charge an internal battery.

[0010] Wireless power is transmitted from the wireless power transmission device to a wireless power receiving device using one or more wireless power transmission coils. The wireless power receiving device has one or more wireless power receiver coils coupled to a rectifier circuit. The rectifier circuit converts received wireless power signals from the wireless power receiver coils into direct current. An illustrative wireless power system (wireless charging system) is shown in Fig. 1 shown. As in Fig. As shown in Figure 1, the wireless power system 8 includes a wireless power transmission device, such as a wireless power transmission device 12, and a wireless power receiving device, such as a wireless power receiving device 24. The wireless power transmission device 12 includes a control circuit 16. The wireless power receiving device 24 includes a control circuit 30. The control circuit in system 8, such as the control circuit 16 and the control circuit 30, is used to control the operation of system 8. This control circuit may include a processing circuit associated with microprocessors, power management units, baseband processors, digital signal processors, microcontrollers, and / or application-specific integrated control circuitry with processing circuitry.The processing circuit implements desired control and communication features in devices 12 and 24. For example, the processing circuit can be used for coil selection, determining power transfer levels, processing sensor data and other data for foreign object detection and performing other tasks, processing user input, handling negotiations between devices 12 and 24, sending and receiving in-band and out-of-band data, taking measurements, and otherwise controlling the operation of System 8. Control circuitry in System 8 can be configured to perform operations in System 8 using hardware (e.g., dedicated hardware or switching logic), firmware, and / or software. Software code for performing operations in System 8 is stored on non-transient, computer-readable storage media (e.g., USB flash drives).The software code is stored on physical, computer-readable storage media in the control circuit 8. The software code may sometimes be referred to as software, data, program instructions, instructions, or code. The non-transitory computer-readable storage media may include non-volatile memory, such as non-volatile memory (NVRAM), one or more hard disks (e.g., magnetic drives or solid-state drives), one or more removable flash drives or other removable media, or the like. Software stored on the non-transitory computer-readable storage media may be executed on the processing circuit logic of the control circuit 16 and / or 30. The processing circuit may include an application-specific integrated control circuit with processing circuitry, one or more microprocessors, a central processing unit (CPU), or other processing circuitry.

[0011] The device 12 can be a standalone power adapter (e.g., a wireless charging mat or charging disc that includes power adapter switching logic), a wireless charging mat or charging disc coupled to a power adapter or other equipment by a cable, a portable device, equipment installed in furniture, a vehicle, or another system, a removable battery case, or other wireless power transfer equipment. Illustrative configurations in which the wireless power transfer device 12 is a wireless charging mat are sometimes described herein as an example.

[0012] The power receiving device 24 can be a portable electronic device, such as a wristwatch, mobile phone, laptop computer, tablet computer, accessory such as earphones, or other electronic equipment. The power transmitting device 12 can be connected to a wall outlet (e.g., an AC power source), can include a battery for providing power, and / or can include another power source. The power transmitting device 12 can include an AC-DC power converter, such as an AC-DC power converter 14, for converting AC power from a wall outlet or other power source into DC power. DC power can be used to power the control circuit 16.During operation, a controller in the control circuit 16 uses a power transfer circuit 52 to transmit wireless power to a power receiving circuit 54 of the device 24. The power transfer circuit 52 may include switching logic (e.g., an inverter 61 formed from transistors) that is switched on and off based on control signals from the control circuit 16 to generate AC signals through one or more wireless power transfer coils, such as coil 36. These coil drive signals cause the coil(s) 36 to transmit wireless power. The coils 36 may be arranged in a planar coil array (e.g., in configurations where the device 12 is a wireless charging mat) or may be arranged to form a cluster of coils (e.g., in configurations where the device 12 is a wireless charging disc).In some arrangements, the device 12 (e.g., a charging mat, a charging disc, a portable device, etc.) may have only a single coil. In other arrangements, a wireless charging device may have multiple coils (e.g., two or more coils, 5-10 coils, at least 10 coils, 10-30 coils, fewer than 35 coils, fewer than 25 coils, or any other suitable number of coils).

[0013] When alternating currents pass through one or more coils 36, electromagnetic (e.g., magnetic) alternating current fields (wireless power signals 44) are generated, which are received by one or more corresponding receiving coils, such as the coil(s) 48 in the power receiving device 24. The device 24 can have a single coil 48, at least two coils 48, at least three coils 48, at least four coils 48, or any other suitable number of coils 48. When the electromagnetic alternating current fields are received by the coil(s) 48, corresponding alternating currents are induced in the coil(s) 48.A rectifier circuit, such as rectifier circuit 50, which contains rectifier components such as synchronous rectifier metal oxide semiconductor transistors arranged in a bridge network, converts received alternating current signals (received alternating current signals that are associated with electromagnetic signals 44) from one or more coils 48 into direct current voltage signals for the power supply of the device 24.

[0014] The DC voltage generated by the rectifier circuit 50 (sometimes referred to as the rectifier output voltage Vrect) can be used to charge a battery, such as the battery 58, and can be used to power other components in the device 24, such as input / output devices 56. The input / output devices 56 may include input devices for collecting user input and / or performing environmental measurements, and may include output devices for providing output to a user.As an example, the input-output devices 56 may include a display for generating visual outputs, a loudspeaker for presenting outputs as audio signals, LED status indicator lights and other light-emitting components for emitting light that provides status information and / or other information to a user, haptic devices for generating vibrations and other haptic outputs, and / or other output devices. The input-output devices 56 may also include sensors for collecting inputs from a user and / or for performing measurements of the environment of the system 8. Illustrative sensors that may be included in the input-output devices 56 include: three-dimensional sensors (e.g.,Three-dimensional image sensors, such as structured light sensors that emit light beams and use two-dimensional digital image sensors to collect image data for three-dimensional images of light points that are generated when a target is illuminated by the light beams; binocular three-dimensional image sensors that capture three-dimensional images using two or more cameras in a binocular imaging setup; three-dimensional lidar sensors (light detection and distance measurement); three-dimensional radio frequency sensors or other sensors that collect three-dimensional image data; cameras (e.g., infrared and / or sight cameras with respective infrared and / or digital sight sensors and / or ultraviolet light cameras); eye-tracking sensors (e.g.,an eye-tracking system based on an image sensor and, if desired, a light source that emits one or more light beams which are tracked by a user's eyes after reflection from the image sensor), touch sensors, buttons, capacitive proximity sensors, light-based (optical) proximity sensors, other proximity sensors, pressure sensors, sensors such as switch-based pressure sensors, gas sensors, pressure sensors, humidity sensors, magnetic sensors, audio sensors (microphones), ambient light sensors, optical sensors for performing spectral measurements and other measurements on target objects (e.g., by emitting light and measuring reflected light), microphones for capturing voice commands and other audio input, distance sensors, sensors configured to collect information about motion, position, and / or orientation (e.g.,Accelerometers, gyroscopes, compasses, and / or inertial measurement units (all of which include one or two of these sensors), sensors such as keys that detect keystroke inputs, joysticks with sensors that detect joystick movement, keyboards, and / or other sensors. The wireless power transmission device 12 may include one or more input / output devices 70 (e.g., input devices and / or output devices of the type described in conjunction with input / output devices 56), or the input / output devices 70 may be omitted (e.g., to reduce the complexity of the device).

[0015] Device 12 and / or device 24 can communicate wirelessly using in-band or out-of-band communication. For example, device 12 can include a wireless transceiver circuit 40 that wirelessly transmits out-of-band signals to device 24 using an antenna. The wireless transceiver circuit 40 can be used to wirelessly receive out-of-band signals from device 24 using the antenna. Device 24 can include a wireless transceiver circuit 46 that transmits out-of-band signals to device 12. A receiver circuit in the wireless transceiver 46 can use an antenna to receive out-of-band signals from device 12. In-band transmissions between devices 12 and 24 can be performed using coils 36 and 48.In an illustrative configuration, frequency-shift keying (FSK) is used to transfer in-band data from device 12 to device 24, and amplitude-shift keying (ASK) is used to transfer in-band data from device 24 to device 12. Power can be wirelessly transmitted from device 12 to device 24 during these FSK and ASK transfers.

[0016] It is desirable that the power transmission device 12 and the power reception device 24 be able to communicate information such as received power, charge states, and the like to control the wireless power transmission. However, the technology described above need not involve the transmission of personally identifiable information to function. It should be noted, however, that to the extent that an implementation of this charging technology involves the use of personally identifiable information, implementers should comply with privacy policies and practices that are generally recognized as meeting or exceeding industry or regulatory requirements for protecting user privacy.In particular, personally identifiable information should be managed and handled in such a way as to minimize the risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

[0017] The control circuit 16 includes a measuring circuit 41. The measuring circuit 41 can be used to detect external objects on the charging surface of the housing of the device 12 (e.g., on the top of a charging mat or, if desired, to detect objects near the coupling surface of a charging disc). The housing of the device 12 can have polymer walls, walls made of another dielectric, metal structures, fabric, and / or other housing wall structures enclosing the coils 36 and other circuits of the device 10. The charging surface can be a smooth outer surface of the upper housing wall of the device 12. The circuit 41 can detect foreign objects such as coils, paper clips, and other metallic objects and can detect the presence of wireless power receiving devices 24 (e.g., the circuit 41 can detect the presence of one or more coils 48).During object detection and marking operations, the external object measurement circuit 41 can be used to perform measurements on coils 36 to determine whether devices 24 are present on the device 12.

[0018] In an illustrative arrangement, the measurement circuit 41 of the control circuit 16 includes a signal generation circuit (e.g., an oscillator circuit for generating AC probe signals with one or more probe frequencies, a pulse generator capable of producing pulses so that impulse responses can be measured to gather inductance information from the frequency of the ringing signals generated in response to the pulses, Q-factor information from the decay envelope of the ringing signals, etc.) and signal acquisition circuitry (e.g., filters, analog-to-digital converters, impulse response measurement circuits, etc.). In some configurations, Q-factor measurements, inductance measurements, and other measurements can be performed (e.g., before the wireless power transmission operations have started, during the wireless power transmission, during pauses between power transmission periods, and / or at other suitable times).Switching circuits in the device 12 can be used to switch on desired coils during measurements on the coils 36, during wireless power transmission, etc.

[0019] The measuring circuit 43 in the control circuit 30 can include a signal generator circuit, a pulse generator circuit, a signal acquisition circuit, and other circuits and / or a measuring circuit (e.g., a circuit of the type described in conjunction with circuit 41 in control circuit 16). Circuit 41 and / or circuit 43 can be used to perform current and voltage measurements, transmit and receive power measurements for power transmission efficiency estimations, coil Q-factor measurements, coil inductance measurements, coupling coefficient measurements, and / or other measurements. Based on this information or other information, the control circuit 30 can control the operation of devices 12 and 24. For example, the measuring circuit 41 can measure the coil(s) 36 to determine the inductance(s) and Q-factor value(s) for the coil(s) 36, measure the power transferred in the device 12 (e.g.B. by measuring the DC voltage supplying inverter 61 and the DC current of inverter 61 and / or by otherwise measuring voltages and currents in the wireless power transmission circuit of the device 12) and other measurements of operating parameters associated with the wireless power circuit and other components in the device 12. In the device 24, the measuring circuit 43 can measure the coil(s) 48 to determine the inductance(s) and Q-factor value(s) for these coil(s), measure the power received in the device 24 (e.g., by measuring the output current and output voltage Vrect of rectifier 50 and / or by otherwise measuring voltages and currents in the wireless power receiving circuit of the device 24) and other measurements of the operating parameters associated with the wireless power circuit and other components in the device 24.

[0020] Such measurements taken during the negotiations between devices 24 and 12 to establish normal power transmission (e.g., during initial setup procedures for wireless power transmission before the wireless power is ramped up to a level useful for charging the battery) and / or later during wireless power transmission operations can be used to configure system 8 (e.g., wireless power transmission and reception circuitry) to improve the wireless power transmission settings. Such measurements can also be used to determine whether power is being lost due to the presence of a foreign object (e.g., a paper clip, a coin, or any other metallic object) between or near devices 12 and 24.For example, the amount of power received can be compared with the amount of power transmitted to determine if there are losses attributable to induced eddy currents in a foreign object.

[0021] This approach to comparing transmitted and received power levels, sometimes referred to as foreign object detection by power metering or power meter foreign object detection, can be used during normal wireless power transmission. If a foreign object is detected during normal wireless power transmission operations, appropriate actions can be taken. For example, the amount of wireless power transmitted can be reduced, wireless power transmission can be stopped, a warning can be issued to a user, and / or other actions can be taken.

[0022] Foreign object detection operations can also be performed before normal wireless power transfer operations have begun. For example, measurements using circuit 41 and / or 43 (e.g., measurements of currents, voltages, inductances, Q-factors, and other operating parameters) can be taken during preliminary interactions between devices 12 and 24 (e.g., when a user initially places device 24 near device 12 for charging, such as when a user initially places device 24 on a charging surface of device 12). During these preliminary interactions, sometimes referred to as digital ping operations, device 12 provides device 24 with a relatively small amount of power (e.g., 200 mW or another small amount) to activate the control circuitry in device 24 (e.g., without other load circuitry in device 24, such as a display circuit, battery charging circuit, etc.).to supply power). By supplying power to the control circuit and its associated communication circuit in device 24, devices 12 and 24 can negotiate via a wireless link (e.g., an in-band link) to determine a suitable wireless power transmission level for system 8 for use during subsequent wireless power transmission operations (e.g., a significantly larger power such as 5 W, 10 W, or another relatively large value associated with normal wireless power transmission operations, generally at least 5 times, at least 10 times, or at least 25 times greater than the transmit power of the digital ping power).

[0023] To inform a user that wireless power transfer operations (e.g., operations associated with charging battery 58) are proceeding correctly (e.g., to inform the user that this process was not completed due to the presence of a foreign object), a warning can be provided to the user. The warning, sometimes referred to as an audible signal, can include an audio and / or visual output displayed on device 24 (as an example). For instance, an audible signal can include the display of an audible tone and a visual user interface indicator (e.g., a battery charging icon). Providing the audible signal reassures the user that the charging operations are proceeding normally (e.g., allowing the user to safely leave system 8 and move away from devices 12 and 24 until charging is complete).

[0024] Digital ping operations are typically performed relatively quickly (e.g., over a period of 200 ms or less, less than 500 ms, less than 1 s, or other relatively short periods). Subsequent negotiations between Device 12 and Device 24, which lead to the commencement of normal (high-power) power transmission operations, can take considerably longer (e.g., several seconds or more). If the tone signal is significantly delayed (e.g., for more than one second or so), the user may notice that wireless power transmission operations are not proceeding normally. Conversely, if the tone signal sounds before System 8 has determined that no foreign objects are present, there is a risk that any foreign object present will be detected only later (e.g.,during normal operation using a power metering foreign object detection technique, at a time when the user may already be away and unable to be present to observe that the charging processes have not taken place).

[0025] To ensure that the tone signal is provided early enough, the tone signal can occur during digital ping operations. This provides the user with prompt assurance (e.g., within one second or less) that wireless power is being transmitted normally and that the battery device is charging satisfactorily (e.g., after many minutes or hours). To avoid unwanted false tone signals (which are later invalid because a foreign object is only detected during normal wireless power transmission during power metering operations), foreign object detection operations are also performed early. In particular, foreign object detection is performed during digital ping operations. In response to the determination that no foreign object is present during these digital ping foreign object detection operations, the user can (e.g.,The audio signal is presented via a loudspeaker, a display, and / or other output devices in the device 24). Illustrative procedures in connection with the use of system 8 are shown in . Fig. 2 shown.

[0026] During operations at Block 80, the system can perform 8 low-power ping operations before digital ping operations are performed. During these operations, the device 24 can use the measuring circuit 43 to measure the coil inductance for the coil(s) 36 and / or perform other measurements. If the wireless power receiving device 24 is present on the charging surface of the device 24, the structures of the device 24 (e.g., coil(s) 48 and associated magnetic core material) will modify (e.g., increase) the measured coil inductance value(s) of the corresponding coil(s) 36 that are overlapped by the device 24.Accordingly, the coil inductance measurements taken during the low-power operations of block 80 allow device 12 to determine whether device 24 is present and, consequently, to determine that device 12 should begin performing digital ping operations at block 82. If the coil inductances of coils 36 remain unchanged, operations at block 80 can continue. However, if the presence of a wireless power receiving device is detected, operations at block 82 can continue.

[0027] During digital ping operations at block 82, device 12 can transmit small amounts of wireless power (e.g., 200 mW) to device 24. This transmission power level is significantly lower than normal wireless power transmission levels (e.g., normal levels of 5 W or more) and is therefore not used when performing wireless charging of the battery 58 in device 24 or when powering load components such as a display and other input / output devices 58. However, the transmitted digital ping power level is sufficient to power the communication circuitry in device 24 (e.g., in the band communication circuitry in control circuitry 30).

[0028] During the operations at Block 82, devices 12 and 24 collect measurements of the operating parameters associated with System 8 while wireless power is transmitted from device 12 to device 24 at the reduced wireless ping power level. For example, measuring circuit 41 can measure coil(s) 36 to determine the inductance(s) and Q-factor value(s) for coil(s). Control circuit 16 can also use measuring circuit 41 to measure power transmission efficiency. For example, control circuit 16 can measure the power transmitted in device 12 (e.g., by measuring the DC voltage supplying inverter 61 and the DC current of inverter 61, and / or by otherwise measuring voltages and currents in device 12's wireless power transmission circuit), and control circuit 30 can measure the power received from device 24.Based on the transmitted power and the received power measurements, the efficiency can be estimated. Other measurements of the operating parameters associated with the wireless power circuit and other components in the device 12 can also be performed, if desired. In the device 24, the measuring circuit 43 can measure the coil(s) 48 to determine the inductance(s) and Q-factor value(s) for these coil(s). The measuring circuit 43 can also measure operating parameters such as the received power in the device 24 (e.g., by measuring the output current and output voltage Vrect of the rectifier 50 and / or by otherwise measuring voltages and currents in the wireless power receiving circuit of the device 24) and other operating parameters associated with a wireless power circuit and other components in the device 24. Measurements performed in the device 24 (e.g.,Using circuit 43, data can be transmitted from device 24 to device 12 (e.g., using in-band communication during digital ping operations). If desired, a coupling coefficient associated with the magnetic coupling between coil 36 and coil 48 can be specified.

[0029] Based on these measurements, the current operating state of System 8 can be analyzed to determine whether a foreign object is present. For example, during operations at Block 84 (which may occur during or shortly after digital ping operations), System 8 (e.g., Device 12) can determine the efficiency of the normal wireless power transmission operations that are just beginning, based on measurements of transmitted and received power levels and / or other measurements, and can compare this predicted power transmission efficiency with predetermined foreign object detection criteria. For example, the efficiency value can be compared with a predetermined efficiency threshold (e.g., a lower efficiency threshold). If the efficiency value exceeds the efficiency threshold, Device 12 can conclude that no foreign object is present.If the efficiency value does not exceed the threshold, the device 12 can conclude that a foreign object is present.

[0030] System 8 can use other foreign object detection criteria to determine whether a foreign object is present, in addition to or instead of detecting foreign objects by comparing a measured efficiency of the wireless power transmission with an efficiency threshold. For example, the Q-factor of the wireless power transmission coil(s) 36 and the Q-factor of the wireless power receiver coil(s) 48 can be measured by circuits 41 and 43. The Q-factors can then be compared with a Q-factor threshold (e.g., a value of 20-40, 30, or another suitable threshold value). If the measured Q-factor for either the transmitting coil or the receiver coil does not exceed the Q-factor threshold, device 12 can infer that a foreign object is present. If the Q-factor does exceed the threshold, device 12 can infer that a foreign object is present.

[0031] Another illustrative technique for detecting a foreign object during digital ping operations involves measuring the inductance values ​​of the transmitter coil (using measuring circuit 41) and the receiver coil (using measuring circuit 43). The measured inductance may be reduced due to the presence of a foreign object (e.g., a foreign object made of a magnetic material). Accordingly, the device 12 can compare the measured inductance values ​​with an inductance threshold. If either the transmitter coil inductance or the receiver coil inductance does not exceed the predetermined inductance threshold, the device 12 can conclude that a foreign object is present. Otherwise, the device 12 can conclude that no foreign object is present.

[0032] An additional technique for determining whether a foreign object is present involves estimating the magnetic coupling coefficient k between coil 36 and coil 48. The coupling coefficient k can be estimated from measurements such as the DC input voltage to inverter 61, the Vrect value at the output of rectifier 50, and other system parameters. If k does not exceed a predetermined threshold (e.g., because the magnetic coupling is impaired due to the presence of aluminum foil or another foreign object that tends to shield magnetic fields), the device 12 can conclude that a foreign object is present. If k exceeds the coupling coefficient threshold, the device 12 can conclude that no foreign object is present.

[0033] In addition to these foreign object detection techniques (e.g., techniques that include foreign object detection criteria such as an efficiency threshold, Q-factor threshold, inductance threshold, and coupling coefficient threshold), System 8 (e.g., Device 12) can compare other measured system operating parameters with other thresholds and / or base a decision on whether a foreign object is present on information associated with two or more of these measurements (e.g., using one or more thresholds or other suitable foreign object detection criteria). The preceding examples of determining whether a foreign object is present based on information gathered from measurements taken during digital ping operations are illustrative. In some embodiments, the combination of efficiency, Q-factor, inductance, and coupling coefficient is used as a regression (e.g.,linear) modeled to determine if a foreign object is present.

[0034] After determining whether a foreign object is present based on information gathered during the digital ping, operations continue at block 86 or block 88. In response to the detection of a foreign object, System 8 (e.g., Device 12 and / or Device 24) may choose not to provide an audio signal to the user (block 86). Other appropriate actions may also be taken. For example, Device 12 may choose not to transmit wireless power (e.g., by reverting to the digital ping operations at block 82 without initiating negotiations with Device 24 to initiate full power transmission). As another example, Device 12 and / or Device 24 may issue a foreign object warning to the user (visually on the display of Device 24, audibly using a speaker in Device 24, etc.).), which informs the user that a foreign object is present, that normal wireless power transmission operations are not taking place, etc.

[0035] If, during the operations of blocks 82 and 84, it is determined that no foreign object is present (no foreign object is located between or near devices 12 and 24, so the wireless power transfer operations can continue), device 12 and / or device 24 can be used to provide the user with an appropriate notification. For example, during the operations at block 88, an audible signal can be provided to the user indicating that charging is proceeding normally. The audible signal can include visual information such as a battery charging icon (e.g., an icon displayed on the device 24 screen that includes charge status information for battery 58, and / or other charge status information such as an icon indicating that charging is starting), text (e.g.,The audio signal may include text indicating the battery charge level (such as "50%", which shows that battery 58 has a charge level of 50%) and / or other visual information that informs the user that charging is proceeding normally (e.g., because no foreign object was detected during digital ping operations). The audio signal may also include an audible output. For example, the device 24 may provide the user with an audio output, such as a tone indicating that charging is proceeding normally, via a speaker in the device 24. The device 24 may provide the audio signal upon receiving an instruction wirelessly received from the device 12 (e.g., via in-band communication), or the device 24 may detect that no foreign object is present by the device 12 proceeding with wireless power transfer negotiations or other operations that implicitly indicate that no foreign object has been detected.If desired, the device 12 may include an output device (e.g. a loudspeaker, a display, a light-emitting device, etc.) to provide audio signal information to the user, instead of or in addition to the device 24 providing the audio signal to the user.

[0036] Regardless of the technique used by Device 12 to cause Device 24 to generate the tone signal, the operations at Block 88 can be performed during the digital ping and / or immediately after the digital ping (e.g., within less than 500 ms, less than 1 s, or less than another suitable short period from the time Device 24 was detected by Device 12 during the low-power ping operations at Block 80). For example, the warning can be issued within less than 0.5 s, less than 1 s, or less than another suitable short period from the time the user placed Device 24 on Device 12's charging surface.Since the audio signal is presented to the user shortly after the device 24 is placed on the charging surface of the device 12, the user receives almost immediate feedback as to whether the charging operations (wireless power transfer operations) are proceeding normally or have been adversely affected by the presence of a foreign object. As a result, the user will not leave the device 24 on the device 12 and leave System 8 with a false impression of its status (as might occur if foreign object detection operations were performed later). Instead, the user is informed almost immediately (e.g., within 1 second or less) that a problem exists. It is helpful that the user is informed while still within range of the device 12.

[0037] After the tone signal is presented to the user at block 88, processing can continue at block 90. ​​During the operations at block 90, system 8 can determine suitable settings for use in normal wireless power transmission. In particular, during the operations at block 90, device 12 and device 24 can communicate with each other, sharing information about the capabilities and / or requirements of devices 12 and 24. For example, devices 12 and 24 can share device identifiers, power transmission and reception capabilities, battery charge status information, desired wireless power levels, and so on. In some embodiments, authentication information can also be exchanged.

[0038] Once negotiations are complete, Device 12 can begin normal wireless power transfer operations to transmit wireless power to Device 24 (Block 92). During the operations at Block 92, power can be transferred at the full power level supported by System 8 (e.g., 10 W, 5 W, or another suitable rated power level) or at a somewhat lower level (e.g., 2.5 W or another suitable reduced amount still well above the digital ping power transfer level). The time required to complete negotiations at Block 90 to establish wireless power transfer and to initiate power transfer at Block 92 can be several seconds or potentially significantly longer.Since the tone signal sounds at block 88 before wireless power transfer operations are performed at block 90 to establish normal wireless power transfer operations at block 92, the user is quickly informed of the current operating status of System 8 (e.g., whether a foreign object is present, whether the normal full power charge is proceeding as expected, etc.).

[0039] According to one embodiment, a wireless power transmission device is provided which includes a wireless power transmission circuit configured to transmit wireless power signals to a wireless power receiving device and a control circuit which is used to perform foreign object detection operations during a digital ping and, in response to the determination during the digital ping that no foreign object is present, causes a warning to be triggered.

[0040] According to another embodiment, the control circuit is further configured to initiate wireless power transmission operations in response to the determination during the digital ping that no foreign object is present.

[0041] According to another embodiment, the control circuit is configured to cause the warning to be issued by sending information to the wireless power receiving device, which informs the wireless power receiving device to issue the warning.

[0042] In another embodiment, the control circuit is configured to cause the warning to be issued by the wireless power receiving device. In another embodiment, the warning includes visual information about the battery charge level and audio information indicating that wireless power transfer operations are being initiated to charge a battery in the wireless power receiving device, and the control circuit is configured to cause the warning to be issued by the wireless power receiving device.

[0043] According to another embodiment, the control circuit is configured to perform the foreign object detection operations by gathering information about the amount of power wirelessly transmitted from the wireless power transmission circuit to the wireless power receiving device during the digital ping.

[0044] According to another embodiment, the control circuit is configured to perform the foreign object detection operations by collecting information about operating parameters associated with the wireless power transmission from the wireless power transmission circuit to the wireless power receiving device.

[0045] According to another embodiment, the control circuit is configured to perform the foreign object detection operations by comparing the collected information with foreign object detection criteria.

[0046] According to another embodiment, the operating parameter information includes information on a Q-factor value associated with a wireless power transmission transmitter coil in the wireless power transmission circuit.

[0047] According to another embodiment, the information on the operating parameters includes information selected from the group consisting of information on the Q-factor, information on the coil inductance, information on the wireless power transmission efficiency, and information on the coupling coefficients.

[0048] According to one embodiment, a wireless power transmission device is provided, which includes a wireless power transmission circuit configured to transmit wireless power signals to a wireless power receiving device control circuit configured to negotiate with the wireless power receiving device to establish wireless power transmission operations, which charge a battery in the wireless power receiving device before the negotiations are conducted, to collect information selected from the group consisting of information on power transmission efficiency, Q-factor information of the wireless power transmitter coil, information on the inductance of wireless power transmitter coils, and coupling coefficient information before the negotiations are conducted, to determine, and to analyze the collected information.to determine whether a foreign object is present, and in response to determining that no foreign object is present, to trigger a warning in order to initiate wireless power transfer operations that charge the battery.

[0049] According to another embodiment, the wireless power transmission device includes a charging surface, wherein the control circuit is configured to collect the information within one second when the wireless power receiving device is placed on the charging surface.

[0050] According to another embodiment, the control circuit is configured to cause the warning to be issued within one second when the wireless power transfer device is placed on the charging surface.

[0051] According to another embodiment, the control circuit is configured to analyze the information by comparing the Q-factor information for the wireless power transmitter coil with a Q-factor threshold.

[0052] According to another embodiment, the control circuit is configured to analyze the information by using information about an amount of wireless power transmitted before conducting the negotiations and an amount of wireless power received before conducting the negotiations, in order to estimate a power transmission efficiency which is compared to an efficiency threshold.

[0053] According to another embodiment, the control circuit is configured to analyze the information by analyzing a coupling coefficient between the wireless power transmission circuit and the wireless power receiving device.

[0054] According to another embodiment, the control circuit is configured to analyze the information by comparing information on the inductance of coils for wireless power transmission with an inductance threshold.

[0055] According to another embodiment, the control circuit is configured to cause the warning to be issued before the negotiations are concluded.

[0056] According to one embodiment, a wireless power transmission device is provided that is configured to transmit wireless power to a wireless power receiving device on a charging surface of the wireless power transmission device. The wireless power transmission device includes a control circuit, a wireless power transmission circuit configured to transmit wireless power signals to the wireless power receiving device after the wireless power receiving device has been placed on the charging surface and before negotiations have been completed between the wireless power receiving device and the control circuit to establish wireless power transmission operations, including charging a battery in the wireless power receiving device. The control circuit is configured to determine whether a foreign object is present.Before negotiations between the wireless power receiving device and the control circuit are completed, using information selected from the group consisting of information on wireless power transmission efficiency, information on magnetic coupling coefficients, information on the inductance of the wireless power transmission transmitter coil, information on the inductance of the wireless power receiver coil, information on the Q-factor of the wireless power transmission transmitter coil, information on the Q-factor of the wireless power receiver coil, and in response to determining that no foreign object is present, triggers warning information to be displayed on a screen of the wireless power receiving device indicating that wireless power transmission operations to charge the battery are beginning.

[0057] According to another embodiment, the control circuit is further configured to cause the warning information to be displayed within one second of the placement of the wireless power receiving device on the wireless charging surface.

[0058] According to one embodiment, a non-volatile, computer-readable storage medium stores one or more programs configured to be executed by one or more processors of a wireless power transfer device, which, when executed, cause a wireless power transfer device to provide wireless power charging operations to a wireless power receiving device, wherein the computer-executable instructions include instructions for carrying out foreign object detection operations during a digital ping, and, in response to the determination during the digital ping that a foreign object is not present, cause a warning to be issued.

[0059] According to another embodiment, a non-volatile, computer-readable storage medium stores one or more programs configured for execution by one or more processors of a wireless power transfer device, which, when executed, cause a wireless power transfer device to provide wireless power charging operations to a wireless power receiving device, wherein the computer-executable instructions include instructions for conducting negotiations with the wireless power receiving device to establish wireless power transfer operations that charge a battery in the wireless power receiving device, and, prior to conducting the negotiations, gathering information selected from the group consisting of information on the efficiency of the wireless power transfer, information on the Q-factor of the wireless power transmitting coil,Information on the inductance of the wireless power transmitter coil and information on the coupling coefficients, to analyze the collected information before conducting the negotiations in order to determine whether a foreign object is present, and in response to determining that no foreign object is present, to cause a warning to be issued, in accordance with the commencement of the wireless power transmission processes which charge the battery.

[0060] According to another embodiment, a non-volatile, computer-readable storage medium stores one or more programs configured to be executed by one or more processors of a wireless power transfer device, which, when executed, cause a wireless power transfer device to provide wireless power charging operations to a wireless power receiving device, wherein the computer-executable instructions include instructions for conducting negotiations with the wireless power receiving device to establish wireless power transfer operations, charging a battery in the wireless power receiving device prior to conducting the negotiations, and gathering information selected from the group consisting of information on wireless power transfer efficiency and information on the Q-factor of the wireless power transfer transmitting coil.Information on the Q-factor of the wireless power transmission receiver coil, information on the inductance of the wireless power transmission transmitter coil, information on the inductance of the wireless power transmission receiver coil, and information on the coupling coefficients during a digital ping prior to conducting negotiations, to analyze the collected information to determine if a foreign object is present, and, in response to determining that a foreign object is not present, to cause warning information to be displayed on the display of a wireless power receiving device indicating that wireless power transmission operations are beginning to charge the battery.

[0061] The foregoing serves only for illustration, and various modifications can be made to the described embodiments. The foregoing embodiments can be implemented individually or in any combination.

Claims

[1] Wireless power transmission device (12), comprising: a wireless power transmission circuit (52) configured to transmit wireless power signals to a wireless power receiving device (24); and Control circuit (16) configured to: Performing foreign object detection operations during a digital ping, including receiving measurements from the wireless power receiving device (24) during the digital ping; and In response to the determination during the digital ping that no foreign object is present based on the received measurements, cause a warning to be issued during the digital ping. [2] Wireless power transmission device (12) according to claim 1, wherein the control circuit (16) is configured to: Initiating wireless power transmission in response to the determination during the digital ping that no foreign object is present. [3] Wireless power transmission device (12) according to claim 1, wherein the control circuit (16) is configured to cause the warning to be issued by sending information to the wireless power receiving device (24) which informs the wireless power receiving device (24) to issue the warning. [4] Wireless power transmission device (12) according to claim 1, wherein the control circuit (16) is configured to cause the warning to be issued by the wireless power receiving device (24). [5] Wireless power transfer device (12) according to claim 1, wherein the warning includes visual information about the battery charge level and audio information indicating that wireless power transfer operations are being started to charge a battery in the wireless power receiving device (24), and wherein the control circuit (16) is configured to cause the warning to be issued by the wireless power receiving device (24). [6] Wireless power transmission device (12) according to claim 1, wherein the control circuit (16) is configured to perform the foreign object detection operations by collecting information about a power quantity that is wirelessly transmitted from the wireless power transmission circuit (52) to the wireless power receiving device (24) during the digital ping. [7] Wireless power transmission device (12) according to claim 6, wherein the received measurements include information about a power quantity received wirelessly by the wireless power receiving device (24) during the digital ping. [8] Wireless power transmission device (12) according to any one of claims 1 to 7, wherein the control circuit (16) is configured to perform the foreign object detection operations by collecting information about operating parameters associated with the wireless power transmission from the wireless power transmission circuit (52) to the wireless power receiving device (24). [9] Wireless power transmission device (12) according to claim 8, wherein the control circuit (16) is configured to perform the foreign object detection operations by comparing the collected information with foreign object detection criteria. [10] Wireless power transmission device (12) according to claim 9, wherein the operating parameter information includes information about a Q-factor value associated with a wireless power transmission transmitter coil (36) in the wireless power transmission circuit (52). [11] Wireless power transmission device (12) according to claim 9, wherein the operating parameter information includes information selected from the group consisting of: Q-factor information and coil inductance information. [12] Wireless power transmission device (12) according to claim 9, wherein the information on the operating parameters includes information on wireless power transmission efficiency. [13] Wireless power transmission device (12) according to claim 9, wherein the information on the operating parameters includes information on coupling coefficients. [14] Non-volatile, computer-readable storage medium storing one or more programs configured to be executed by one or more processors of a wireless power transfer device (12), which, when executed, cause a wireless power transfer device (12) to provide wireless power charging to a wireless power receiving device (24), wherein the computer-executable instructions include: Performing foreign object detection operations during a digital ping by receiving measurements from the wireless power receiving device (24) during the digital ping; and In response to the determination during the digital ping that no foreign object is present based on the received measurements, cause a warning to be issued during the digital ping. [15] Non-volatile computer-readable storage medium according to claim 14, further comprising instructions for initiating wireless power transfer operations in response to the determination during the digital ping that a foreign object is not present.

Images