Wireless power systems with shared inductive loss scaling factors

Abstract

The wireless power system includes a wireless power transmitting device having a wireless power transmitting coil and an inverter. The inverter and the wireless power transmitting coil are used to transmit a wireless power signal. The wireless power system also includes a wireless power receiving device configured to receive the wireless power signal using a wireless power receiving coil. A rectifier in the wireless power receiving device rectifies the AC signal from the wireless power receiving coil and generates a corresponding DC power. The power loss calculation can be used to help determine whether a foreign object may be present in the vicinity of the coupled wireless power transmitter and receiver. In an ecosystem with multiple models of transmitters and multiple models of receivers, the model-dependent scaling factor can be maintained and exchanged between a given coupled transmitter and receiver pair to enable accurate power loss estimation.

Description

[Technical field]

[0001] This application claims priority to U.S. Patent Application No. 17 / 681,363, filed February 25, 2022, and U.S. Provisional Patent Application No. 63 / 167,971, filed March 30, 2021, each of which is incorporated by reference in its entirety.

[0002] The present application relates generally to power systems, and more particularly to wireless power systems for charging electronic devices. [Background technology]

[0003] In the wireless charging system, a wireless power transmitting device wirelessly transmits power to a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit a wireless power signal to the wireless power receiving device. The wireless power receiving device has a coil and a rectifier circuit. The coil of the wireless power receiving device receives an AC wireless power signal from the wireless power transmitting device. The rectifier circuit converts the received signal into DC power. Summary of the Invention

[0004] The wireless power transmitting device can wirelessly transmit power to the wireless power receiving device. In each wireless power transmitting device, an inverter and a wireless power transmitting coil are used to transmit the wireless power signal. The wireless power receiving device can be magnetically coupled to the wireless power transmitting device so that power can be transferred from the transmitting device to the receiving device. In each wireless power receiving device, the wireless power receiving coil is used to receive the wireless power signal from the paired transmitting device. A rectifier in the wireless power receiving device rectifies the AC signal from the wireless power receiving coil and generates a corresponding DC power.

[0005] The power loss calculation may be used to help determine whether a foreign object may be present in the vicinity of a coupled wireless power transmitter and receiver. If the estimated foreign object power loss value is determined to be below a predetermined threshold, wireless power transfer operations may proceed normally. However, if the estimated foreign object power loss value is determined to exceed a predetermined threshold, it may be concluded that a foreign object is present and normal power transfer operation may be stopped or otherwise discontinued.

[0006] In an ecosystem with multiple models of transmitters and multiple models of receivers, scaling factors may be maintained by the transmitters and receivers. These scaling factors may be exchanged between the transmitter and receiver in a coupled transmitter-receiver pair to enable accurate power loss estimation.

[0007] Ecosystem scaling techniques can also be used more generally to adjust runtime models of other types in coupled systems, such as systems with multiple types of transmitters and receivers. This can be useful for any algorithm that relies on these models to calculate characteristics in coupled systems. As an example, ecosystem scaling can be used in wireless power transfer systems when estimating coupling between transmitters and receivers, or when estimating maximum power delivery or inter-coil efficiency of power delivery. In general, any ecosystem with different possible combinations of coupled devices can exchange scaling coefficients and / or other parameters at runtime to enable accurate coupling models for the coupled devices. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an exemplary wireless power system according to one embodiment. [Diagram 2] 1 is a circuit diagram of an exemplary wireless power system according to one embodiment. [Diagram 3]4 is a flowchart of example operations associated with the use of a device in a wireless power system, according to an embodiment. [Figure 4] 4 is a flowchart of example operations associated with the use of a device in a wireless power system, according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The wireless power system includes a wireless power transmitting device. The wireless power transmitting device wirelessly transmits power to the wireless power receiving device. The wireless power transmitting device may be a charging pack, a charging mat, a portable electronic device with power transmitting capability, a removable battery case with power transmitting capability, or other power transmitter. The wireless power receiving device may be a device such as a watch, a mobile phone, a tablet computer, a laptop computer, a removable battery case, an electronic device accessory, or other electronic device. The wireless power receiving device uses power from the wireless power transmitting device to power the receiving device and to charge an internal battery.

[0010] Wireless power is transmitted from the wireless power transmitting device to the wireless power receiving device by driving current through one or more wireless power transmitting coils using an inverter in the wireless power transmitting device. The wireless power receiving device has one or more wireless receiving coils coupled to a rectifier circuit that converts the received wireless power signal into DC power.

[0011] If a foreign object such as a paper clip, coin, or other metal object is present near the wireless power transmission coil of the wireless power transmission device, eddy currents may be generated in the foreign object, causing the temperature of the foreign object to increase. To determine whether a foreign object is present in the vicinity of the wireless power transmission device, a power loss estimation is performed. For example, the amount of power loss in the transmitter and the amount of power loss in the receiver are estimated. By comparing the measured output power from the rectifier circuit with the amount of input power to the inverter and subtracting the estimated transmitter and receiver losses, the amount of power that may have been absorbed by the foreign object can be calculated. If the estimated foreign object power is higher than a threshold, power delivery can be stopped and / or other suitable actions can be taken.

[0012] In order to accurately estimate the foreign object power loss value, various potential sources of power loss in a wireless power system must be considered. Some power losses exhibited by the power transmitter and receiver are independent of the magnetic properties of the transmitter and receiver (e.g., switching losses, losses dependent on the drain-source resistance of field effect transistors in inverters and rectifiers, etc.). Losses such as these can be taken into account by characterizing the relevant device components (e.g., by ascertaining the drain-source resistance of the transistors using measurements made during manufacturing and / or other testing).

[0013] Transmitters and receivers also exhibit power losses that depend on the inductive properties of the transmitter and receiver (e.g., losses that depend on the magnetic properties of the coupled transmitter and receiver, sometimes referred to as coupling-dependent losses, inductive losses, magnetic losses, etc.). Examples of power losses that depend on the magnetic properties of the transmitter and receiver include 1) coil losses that depend on the alternating current (AC) resistance of the coupled transmit and receive coils, 2) friendly metal losses (e.g., power losses due to eddy currents induced in the metal housing of the receiving device, and 3) foreign object losses that occur when a foreign object is present between the transmitter and receiver. Power losses such as these that depend on the magnetic properties of the transmitter and receiver may be characterized in terms of LQK magnetic parameters, where L refers to the inductance of the transmit and receive coils, Q refers to the quality factor of the coils, and K refers to the magnetic coupling of the coils.

[0014] In a wireless power ecosystem with many different transmitters and receivers, each pairing between a given one of the transmitters and a given one of the receivers will result in a potentially different set of magnetic properties, thereby posing a challenge to accurate assessment of power loss that depends on the magnetic properties of the coupled transmitter-receiver pair. To facilitate accurate transmitter and receiver power loss estimation, measurements between various models of transmitters and receivers and reference units (e.g., reference transmitters and reference receivers) can be used to determine magnetic power loss parameters associated with the transmitters and receivers. Characterization information from measurements made with the reference transmitters and / or reference receivers can be stored for each different model of device and then used to help ensure that an accurate power loss estimation is made when a particular model transmitter is paired with a particular model receiver.

[0015] An exemplary wireless power system (wireless charging system) is shown in FIG. 1. As shown in FIG. 1, the wireless power system 8 includes a wireless power transmitting device, such as wireless power transmitting device 12, and a wireless power receiving device, such as wireless power receiving device 24. The wireless power transmitting device 12 includes a control circuit 16. The wireless power receiving device 24 includes a control circuit 30. The control circuitry within the system 8, such as the control circuitry 16 and the control circuitry 30, is used in controlling the operation of the system 8. The control circuitry may include a processing circuit associated with a microprocessor, a power management unit, a baseband processor, a digital signal processor, a microcontroller, and / or an application specific integrated circuit having processing circuitry. The processing circuitry performs desired control and communication functions within the device 12 and the device 24. For example, the processing circuitry may be used to process user input, handle negotiations between the device 12 and the device 24, transmit and receive in-band and out-of-band data, perform measurements, estimate power loss, determine power transmission levels, and otherwise control the operation of the system 8.

[0016] The control circuitry in the system 8 may be configured to execute operations in the system 8 using hardware (e.g., dedicated hardware or circuitry), firmware, and / or software. Software code and other data for executing operations in the system 8 are stored on a non-transitory computer-readable storage medium (e.g., a tangible computer-readable storage medium) in the control circuitry 8. The software code may be referred to as software, data, program instructions, instructions, or code. The non-transitory computer-readable storage medium may include non-volatile memory such as a 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, etc. The software stored on the non-transitory computer-readable storage medium may be executed on the processing circuitry of the control circuitry 16 and / or 30. The processing circuitry may include an application specific integrated circuit having processing circuitry, one or more microprocessors, a Central Processing Unit (CPU), or other processing circuitry.

[0017] The power transmitting device 12 may be a stand-alone power adapter (e.g., a wireless charging mat or charging pack that includes power adapter circuitry), a wireless charging mat or pack that is coupled to a power adapter or other equipment by a cable, a portable device, equipment integrated into furniture, a vehicle, or other system, a removable battery case, or other wireless power transmission equipment.

[0018] The power receiving device 24 may be a portable electronic device, such as a wristwatch, a mobile phone, a laptop computer, a tablet computer, an accessory for an electronic device, such as an earphone or a wirelessly rechargeable removable battery case, or other electronic equipment. The power transmitting device 12 may be coupled to a wall outlet (e.g., an AC power source), may have a battery for providing power, and / or may have another power source. The power transmitting device 12 may have 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 to direct current (DC) power. The DC power may be used to power the control circuit 16. In operation, a controller in the control circuit 16 transmits wireless power to the power receiving circuit 54 of the device 24 using the 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 through one or more wireless power transmitting coils, such as the wireless power transmitting coil(s) 36. These coil drive signals cause the coil(s) 36 to transmit wireless power. The multiple coils 36 may be arranged in a planar coil array (e.g., in a configuration where the device 12 is a wireless charging mat) or may be arranged to form a cluster of coils (e.g., in a configuration where the device 12 is a wireless charging puck). In some configurations, the device 12 (e.g., a charging mat, puck, etc.) may have only a single coil. In other configurations, the wireless charging device may have multiple coils (e.g., 2 or more coils, 2-4 coils, 5-10 coils, at least 10 coils, less than 25 coils, or any other suitable number of coils).

[0019] When an AC current flows through one or more coils 36, it generates an alternating electromagnetic field (e.g., magnetic field) (wireless power signal 44) that is received by one or more corresponding receiving coils, such as coil(s) 48 in the power receiving device 24. The device 24 may 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 AC electromagnetic field is received by the coil(s) 48, a corresponding AC current is induced in the coil(s) 48. The AC signal used in transmitting wireless power may have any suitable frequency (e.g., 100-400 kHz, etc.). A rectifier circuit, such as rectifier circuit 50, including rectifier components, such as synchronous rectifier metal oxide semiconductor transistors arranged in a bridge network, converts the received AC signal (the received AC signal associated with the electromagnetic signal 44) from the one or more coils 48 to a DC voltage signal for powering the device 24.

[0020] The DC voltage generated by rectifier circuit 50 (sometimes referred to as rectifier output voltage Vrect) may be used in charging a battery, such as battery 58, and in powering other components in device 24. For example, device 24 may include input / output devices 56. Input / output devices 56 may include input devices for collecting user input and / or making environmental measurements, and may include output devices for providing output to a user. By way of example, input / output devices 56 may include displays, speakers, cameras, touch sensors, ambient light sensors, and other devices for collecting user input, making sensor measurements, and / or providing output to a user.

[0021] Device 12 and / or device 24 may communicate wirelessly using in-band or out-of-band communications. Device 12 may have a wireless transceiver circuit 40 that wirelessly transmits out-of-band signals to device 24, for example, using an antenna. Wireless transceiver circuit 40 may be used to wirelessly receive out-of-band signals from device 24, using an antenna. Device 24 may have a wireless transceiver circuit 46 that transmits out-of-band signals to device 12. Receiver circuitry within wireless transceiver 46 may receive out-of-band signals from device 12, using an antenna. In-band transmissions between devices 12 and 24 may be performed using coils 36 and 48. In one exemplary configuration, frequency shift keying (FSK) is used to carry in-band data from device 12 to device 24, and amplitude shift keying (ASK) is used to carry in-band data from device 24 to device 12. Power may be carried wirelessly from device 12 to device 24 during these FSK and ASK transmissions.

[0022] The control circuit 16 includes a measurement circuit 41. The measurement circuit 41 may include a voltage measurement circuit (e.g., for measuring one or more voltages within the device 12, such as a coil voltage associated with a wireless power transmitting coil) and / or a current measurement circuit (e.g., for measuring one or more currents, such as a wireless power transmitting coil current).

[0023] The control circuit 30 includes a measurement circuit 43. The measurement circuit 43 may include a voltage measurement circuit (e.g., for measuring one or more voltages within the device 24, such as a coil voltage and / or a rectifier output voltage associated with a wireless power transmitting coil) and / or a current measurement circuit (e.g., for measuring one or more currents, such as a wireless power receiving coil current and / or a rectifier output current).

[0024] 2 illustrates an example wireless power circuit in a system 8 in an example scenario where a wireless power transmitting device is paired with a wireless power receiving device. The wireless power circuit of FIG. 2 includes a wireless power transmitting circuit 52 in the wireless power transmitting device 12 and a wireless power receiving circuit 54 in the wireless power receiving device 24. In operation, a wireless power signal 44 is transmitted by the wireless power transmitting circuit 52 and received by the wireless power receiving circuit 54. The configuration of FIG. 2 includes (as an example) a single transmitting coil 36 and a single receiving coil 48. In other implementations, the voltage on a capacitor 70 is measured and the current through the coil is inferred from the measurement.

[0025] 2, the wireless power transmission circuit 52 includes an inverter circuit 61. The inverter circuit (inverter) 61 can be used to provide a signal to the coil 36. During wireless power transmission, the control circuitry of the device 12 provides a signal to a control input 82 of the inverter 61 that causes the inverter 61 to provide an AC drive signal to the coil 36. A circuit component, such as a capacitor 70, may be coupled in series with the coil 36 as shown in FIG. 2. Measurement circuitry 41 in the device 12 may make measurements related to operating currents and voltages in the device 12. For example, a voltage sensor 41A may be used to measure the coil voltage on the coil 36 and a current sensor 41B may be used to measure the coil current through the coil 36.

[0026] When an alternating current signal is provided to the coil 36, a corresponding alternating electromagnetic signal (wireless power signal 44) is transmitted to a nearby coil, such as the exemplary coil 48 in the wireless power receiving circuit 54. This induces a corresponding alternating current (AC) current signal in the coil 48. A capacitor, such as capacitor 72, may be coupled in series with the coil 48. The rectifier 50 receives the AC current from the coil 48 and generates a corresponding DC power (e.g., a DC voltage Vrect) at an output terminal 76. This power may be used to power a load. The measurement circuit 43 in the device 24 may perform measurements related to operating currents and voltages in the device 24. For example, the voltage sensor 43A may measure Vrect (the output voltage of the rectifier 50), or the voltage sensor may measure the coil voltage on the coil 48. The current sensor 43B may measure the rectifier output current of the rectifier 50, or the current sensor may measure the current in the coil 48.

[0027] The measurements made by measurement circuitry 41 and measurement circuitry 43 may be processed to extract magnetic loss characteristics (e.g., coefficients or other parameters that characterize the amount of power loss in device 12 and device 24 and that depend on the magnetic properties of the transmitter and receiver). These measurements may be stored within each device and exchanged between devices so that device 12 (and, if desired, device 24) can use this information in accurately estimating any foreign object power loss that may be present.

[0028] If desired, these measurements can be used to estimate how well the transmitter and receiver can transmit wireless power and therefore whether to inform the user that the wireless power transmission operation is proceeding normally. For example, these measurements can be used to estimate the magnetic coupling coefficient K, the wireless power transmission efficiency, the estimated foreign object power loss, and / or other attributes of the coupled transmitter-receiver pair. In addition to or instead of estimating the foreign object power loss to determine whether a foreign object is present and therefore whether to proceed with wireless power transmission, the system 10 can use this information (e.g., the estimated foreign object power loss and / or associated coupling and / or efficiency information) to determine whether to present a confirmation message to the user of the system 10 informing the user that the wireless power transmission is proceeding properly (e.g., informing the user that the process was not disrupted by the presence of a foreign object, possible misalignment, or insufficient coupling due to other factors). Exemplary confirmation messages include an audio output, such as a chime, and / or a visual output presented on the device 24. The chime may involve presenting an audible chime sound and a visual user interface affordance (e.g., a battery charging icon or other visual alert displayed on a display within device 24 or other display). Providing the chime reassures the user that the charging operation is proceeding normally (e.g., it allows the user to feel comfortable walking away from system 8 and leaving devices 12 and 24 alone until charging is complete).

[0029] In general, any suitable information may be exchanged between devices in system 8, and this information may be used in any suitable manner. The exchange of measurements such as those obtained using measurement circuitry 41 and measurement circuitry 43, and the use of this information in determining whether a foreign object is present, is exemplary.

[0030] Following measurements using circuits 41 and 43, the amount of power potentially absorbed by a foreign object in system 10 can be determined using Equation 1. PFO=POUT-PIN-PLOSSTX-PLOSSRX (1)

[0031] In Equation 1, PFO represents the amount of power absorbed by foreign objects present (if any), POUT represents the output power (e.g., the output power of rectifier 50), PIN represents the input power (e.g., the input power to coil 36), PLOSSTX represents the power loss due to device 12, and PLOSSRX represents the power loss due to device 24. The values ​​of POUT and PIN can be measured (e.g., using circuits 41 and 43). Mathematical models can be used to generate functional representations of PLOSSTX and PLOSSRX, which can be evaluated using measured operating parameters, such as measurements obtained using circuits 41 and 43. For example, in one exemplary modeling embodiment, PLOSSTX and PLOSSRX can be calculated using Equations 2a and 3a, respectively. PLOSSTX=b * RAIRTX * (ITX) 2 (2a) PLOSSRX=m * RAIRRX * (IRX) 2 +α * (IRX) 2 +αDC (3a)

[0032] In Equation 2a and Equation 3a, ITX represents the transmitter current (e.g., coil current) and IRX represents the receiver current (e.g., rectifier output current or, in some embodiments, receiver coil current). The values ​​of RAIRTX and RAIRRX represent the measured AC coil resistances for coil 36 and coil 48, respectively. The values ​​of b, m, α, and αDC are model parameters (sometimes referred to as magnetic power loss coefficients) that characterize the performance of the coupled transmitter and receiver pair in system 8. The transmitter power loss PLOSSTX is due only to the transmitter coil power loss in the model of Equation 2a. The receiver power loss PLOSSRX has a first component (first term in Equation 3a) due to the receiver coil power loss and a second component (consisting of the last two terms in Equation 3a) that represents friendly metal losses (e.g., losses due to eddy currents induced in the receiver when power is being transmitted). The parameter b may sometimes be referred to as a transmitter coil loss parameter or coefficient. Parameter m may be referred to as a receiver coil loss parameter or coefficient, and parameters α and α may be referred to as friendly metal loss parameters or coefficients. Parameters b, m, α, and α depend on the magnetic interaction between device 12 and device 24 when coupled, and therefore may be referred to as magnetic loss parameters or coefficients.

[0033] In an ecosystem where there are multiple different models of wireless power transmitting devices available to a user (e.g., different models of device 12) and multiple different models of wireless power receiving devices available to a user (e.g., different models of device 24), the magnetic loss parameters will vary depending on which particular transmitter and receiver are paired together. As an example, when a model I transmitter and a model J receiver are paired, the amount of power loss in each device will be different than the amount of power loss experienced when these devices are paired with different devices.

[0034] To account for these variations and thereby ensure accurate estimation of the foreign object power loss in Equation 1, a magnetic power loss parameter scaling factor (sometimes referred to as a magnetic power loss coefficient scaling factor) is used. In particular, the models of PLOSSTX and PLOSSRX in Equation 2a and Equation 2b, which may be inaccurate in an ecosystem having multiple different transmitter and receiver models, may be replaced by Equation 2b and Equation 3b, respectively. PLOSSTX=gb * bR * RAIRTX * (ITX) 2 (2b) PLOSSRX=gm * mR * RAIRRX * (IRX) 2 +gα * αR * (IRX) 2 +gαDC * αRDC (3b)

[0035] In Equation 2b, the transmitter coil loss parameter b is replaced by a reference transmitter coil loss value bR (sometimes referred to as the transmitter coil loss factor) associated with the transmitter loss measured when the reference transmitter is coupled to the reference receiver, and this value is then scaled using a scaling factor gb. In Equation 3b, the receiver coil loss parameter m is replaced by mR (sometimes referred to as the receiver coil loss factor) associated with the receiver coil loss measured when the reference receiver and reference transmitter are coupled, and this value is then scaled using a scaling factor gm. In Equation 3b, the friendly metal loss parameters α and αDC are replaced by the reference friendly metal loss parameters (factors) α and αRDC, respectively, extracted using measurements made at the reference transmitter and reference receiver. The reference friendly metal loss parameters are scaled by their respective scaling factors gα and gαDC.

[0036] By using scaling factors in calculating PLOSSTX (e.g., see Equation 2b) and PLOSSRX (e.g., see Equation 3b), Equation 1 can be satisfactorily evaluated regardless of which model of transmitter and receiver are paired with each other.

[0037] Exemplary operations involved in using measuring transmitters and receivers to determine their scaling parameters are shown in the flow chart of FIG. 3. The operations of FIG. 3 are performed at design time, and the resulting scaling coefficients are stored in production units. Exemplary operations involved in using scaling parameters in system 8 are shown in FIG. 4. The operations of FIG. 4 are performed at run time (e.g., when a transmitter and receiver are paired in preparation for transmitting wireless power between them). In the examples of FIG. 3 and FIG. 4, it is assumed that scaling coefficients for a particular model transmitter (a model I transmitter) and a particular model receiver (e.g., a model J receiver) have been obtained using reference device measurements and are then used when the model I transmitter is paired with the model J receiver. In general, it is expected that this process will be performed for many models of transmitters (models other than model I) and many models of receivers (models other than model J). Furthermore, any of a variety of different models of characterized transmitters may generally be paired by a user with any of a variety of different models of characterized receivers. This is because not all users own the same model transmitter, and not all users own the same model receiver. In this example, an exemplary user pairs a Model I transmitter with a Model J receiver during operation of FIG.

[0038] The operations involved in measuring the magnetic power loss parameter scaling factors of a model I transmitter and a model J receiver are illustrated in FIG. 3. During the operation of block 90, a reference wireless power receiving device is paired (physically or by simulated pairing, such as finite element analysis simulation pairing) with a reference wireless power transmitting device. The physical reference device may be obtained from a centralized source or may be built by different device manufacturers according to a globally disseminated reference design. Once paired, the reference transmitter and reference receiver may begin transmitting power. In particular, during the operation of block 90, the reference transmitter may transmit a wireless power signal to the reference receiver while internal operating parameters (e.g., transmitter and receiver currents and voltages) are measured and stored. From these measurements, the reference magnetic loss parameters are extracted (e.g., values ​​of the reference magnetic loss parameters bR, mR, αR, and αRDC are obtained). In a scenario where a pairing simulation is used instead of measurements on a physically paired device, a finite element analysis simulation is used to determine the LQK of the coupled transmitter-receiver pair, and then a circuit simulation is used to determine the expected currents and voltages. These simulated currents and voltages can then be used to determine the magnetic loss parameters.

[0039] After determining the reference magnetic loss parameters (either by physical measurement or simulation), the model J receiver is paired with the reference transmitter. The model J receiver loss parameter measurements can be obtained while the devices are paired in a simulation, or while the devices are physically paired and wireless power is transmitted from the reference transmitter to the model J receiver. In particular, during the operation of block 92, the model J loss parameters (coefficients) bRj, mRj, αRj, and αRjDC are obtained. The "J" in each of these parameters and the R (for "reference") in each of these parameters indicate that the loss parameters are specific to the scenario in which the model J receiver is operating with the reference transmitter. The model J receiver scaling coefficients gb (Equation 2b) can then be calculated using Equation 4 and stored in all model J wireless power receiving devices (e.g., during manufacturing or later using an update). gb=bRj / bR (4)

[0040] During the operation of block 94, the Model I transmitter is paired with a reference receiver. Power is transmitted wirelessly while transmitter operating parameters (e.g., current and voltage) are measured. From these measurements or simulations, the magnetic loss parameters miR, biR, αiR, and αiRDC of the Model I transmitter are obtained. Scaling coefficients gm, gα, and gαDC of the Model I transmitter are then calculated using Equations 5, 6, and 7. gm=miR / mR (5) gα=αiR / αR (6) gαDC=αiRDC / αRDC (7)

[0041] The Model I transmitter scaling factors are then stored in all Model I transmitters (eg, during manufacturing or later using an update).

[0042] Exemplary operations involved in the use of scaling factors in a Model I transmitter and a Model J receiver in a scenario in which the Model I transmitter and the Model J receiver are paired by a user are illustrated in the flow chart of FIG.

[0043] During operation of FIG. 4, a user having a Model J receiver and Model I transmitter who desires to wirelessly transfer power from the Model I transmitter to a Model J mobile phone pairs the Model I transmitter with the Model J receiver during operation of block 100 (e.g., by magnetically attaching a Model I charging pack to a Model J mobile phone, by way of example only).

[0044] During the operation of block 102, the model I transmitter and model J receiver exchange information such as their scaling factors and transmit power (e.g., using low power in-band communication or other wireless communication). For example, the model J receiver transmits to the model I transmitter the value of the scaling factor g obtained from a model J measurement with a reference transmitter in block 92 of FIG. 3. The model I transmitter transmits to the model J receiver the values ​​of the scaling factors g, gα, and gαDC obtained from a model I measurement with a reference receiver in block 94 of FIG. 3.

[0045] During wireless transfer of power from the Model I transmitter to the Model J receiver, measurement circuitry 41 in the transmitter and measurement circuitry 43 in the receiver can measure operating parameters of the transmitter and receiver (e.g., coil current and voltage, rectifier output voltage and current, etc.) Current and voltage measurements can be exchanged between the transmitter and receiver if desired (e.g., using in-band wireless communication).

[0046] The information measured by circuits 41 and 43 can be used in conjunction with the exchanged scaling factors to calculate PLOSSRX and PLOSSTX using Equations 2b and 3b.

[0047] During operation of block 104, for example, the Model J receiver may measure the rectifier current and rectifier voltage (the product of which is POUT) and use the measurements in conjunction with the scaling factors gm, gα, and gαDC received from the Model I transmitter during operation of block 102 to evaluate Equation 3b, thereby estimating PLOSSRX. The scaling factors received from the Model I transmitter provide the receiver J with information about the expected operating characteristics of the Model I transmitter with respect to receiver coil losses and friendly metal losses.

[0048] As an example, consider receiver coil loss. When receiver J is paired with a reference transmitter, the value of the scaling factor gm is 1.0. The receiver may then use the first term of Equation 3b to determine the receiver coil loss (the receiver coil loss is 1.0 * mR * RAIRRX * (IRX) 2 ), where the values ​​of mR, RAIRRX, and receiver current IRX are known to the receiver. However, in the current situation, receiver J is not paired with the reference transmitter, but instead with transmitter I. Transmitter I may have been predetermined to induce lower coil losses in the coupled receiver than the reference transmitter, and thus the value of gm that transmitter I passed to the model J receiver during block 102 may be 0.9 (as an example). When the model J receiver evaluates equation 3b using the scaling factor value of 0.9 received from the model I transmitter, the model J receiver accurately estimates a somewhat reduced value of PLOSSRX (due to the presence of the model I transmitter, which is known to induce a smaller amount of receiver coil loss than the reference transmitter). As this example demonstrates, by using the scaling factor received from the model I transmitter, the magnetic loss parameters used by the receiver to calculate PLOSSRX can be appropriately scaled to reflect the presence of the model I transmitter instead of the reference transmitter, thereby increasing the accuracy of estimating the value of PLOSSRX.

[0049] During the operation of block 106, the model I transmitter estimates PLOSSTX using the measured transmitter coil current ITX, the known values ​​of bR and RAIRTX, and the scaling factor gb received from the receiver during the evaluation in Equation 2b. The scaling factor gb reflects how the model J receiver is expected to affect the transmitter coil loss in a transmitter paired with the model J receiver instead of the reference receiver. As an example, the model J receiver may tend to cause the paired transmitter to account for a higher transmitter coil loss than the reference receiver. As a result, the value of the scaling factor gb that the model I transmitter receives from the model J receiver may be 1.1 (as an example). When evaluating Equation 2b, the increased scaling factor helps the transmitter I account for the fact that the model I transmitter is coupled to a model J receiver and therefore should expect a larger transmitter coil loss than if it were coupled to a reference receiver.

[0050] During the operation of block 107, the value of PLOSSRX calculated in block 104 may be transmitted to the paired transmitter.

[0051] During the operation of block 108, the system 8 evaluates the value of PFO using Equation 1 (e.g., an estimate of foreign object power loss, if any, is made). By accurately estimating PLOSSTX using the scaling factor information received from the model J receiver and receiving an estimate of PLOSSRX from the model J receiver, the model I transmitter will have both PLOSSTX and PLOSSRX for Equation 1. The value of PIN can be obtained by the transmitter by calculating the product of the transmitter coil current (ITX) and the voltage from the measurement circuitry 41. The value of POUT can be obtained by the transmitter by calculating the product of the receiver coil current IRX and the rectifier output voltage received from the measurement circuitry 43, or by receiving POUT from the receiver.

[0052] After determining the value of PFO during the operation of block 108, the transmitter may compare the PFO to a threshold power loss value (TH). Suitable actions may then be taken by system 8. For example, in response to determining that the PFO is less than TH, it may be concluded that no foreign object is present and may allow the power transfer operation to proceed normally (e.g., so that power may be transferred to charge battery 58). In response to determining that the PFO is greater than TH, the power transfer operation may be limited. Examples of power transfer limitations that may be implemented include canceling all power transfer operations and / or stopping power transfer if already in progress, limiting the maximum amount of power that may be transferred (e.g., to a relatively low, predetermined power level that is below the normal maximum power transfer capability of system 10), and / or issuing a visual, audible, and / or vibration alert to the user. If desired, an alert to the user (e.g., a warning and / or other informational content informing the user that a power transfer operation is not proceeding normally because a foreign object has been detected) may be presented using an output device within device 12 and / or device 24. For example, control circuitry within device 12 may wirelessly communicate with control circuitry within device 24 to issue a visual alert that is presented on a display within device 24 .

[0053] It is desirable for the power transmitting device 12 and the power receiving device 24 to be able to communicate information such as received power, power loss estimates, etc., to control wireless power transmission. However, the above-described technology does not need to involve the transmission of personally identifiable information to function. As an exercise of caution, it is noted that to the extent any implementation of this charging technology involves the use of data communication between the wireless power transmitter and the wireless power receiver, the communicated information must be used to control power delivery, and implementers should follow privacy policies and practices generally recognized as meeting or exceeding industry or government requirements for maintaining user privacy.

[0054] According to one embodiment, a wireless power transmitting device is provided that includes a wireless power transmitting circuit configured to provide wireless power to a wireless power receiving device, the wireless power transmitting circuit having a wireless power transmitting coil configured to transmit a wireless power signal, and a control circuit configured to estimate a foreign object power loss value based at least in part on a magnetic power loss parameter scaling factor exchanged between the wireless power receiving device and the wireless power transmitting device.

[0055] According to another embodiment, the control circuitry is further configured to determine whether to present a user interface affordance based at least in part on the estimated foreign object power loss value.

[0056] According to another embodiment, the control circuitry is further configured to determine whether a foreign object is present based at least in part on the estimated foreign object power loss value.

[0057] According to another embodiment, the wireless power receiving device includes a wireless power receiving device of a given receiver model, and the magnetic power loss parameter scaling factor is a ratio of 1) a transmitter coil loss factor determined by pairing a receiver of the given receiver model to a reference transmitter and 2) a transmitter coil loss factor determined by pairing the reference receiver to a reference transmitter.

[0058] According to another embodiment, the control circuit is configured to wirelessly exchange the magnetic power loss parameter scaling factor upon pairing of the wireless power transmitting device and the wireless power receiving device before the wireless power transmitting circuit begins normal power transmission operation.

[0059] According to another embodiment, the control circuitry is configured to estimate the foreign object power loss value by determining 1) a power input value, 2) a power output value, 3) a transmitter power loss value, and 4) a receiver power loss value.

[0060] According to another embodiment, the receiver power loss value is determined based at least in part on a receiver coil loss value and a friendly metal loss value.

[0061] According to another embodiment, the control circuit is configured to obtain a receiver power loss value from a wireless power receiving device.

[0062] According to another embodiment, the wireless power receiving device includes a wireless power receiving coil, and the magnetic power loss parameter scaling factor is used to scale a transmitter coil loss factor to reflect the dependence of power loss by the wireless power transmitting coil on magnetic coupling between the wireless power transmitting coil and the wireless power receiving coil.

[0063] According to one embodiment, there is provided a wireless power receiving device configured to obtain wireless power from a wireless power transmitting device, the wireless power receiving device including a wireless power receiving circuit having a wireless power receiving coil configured to receive a wireless power signal, and a control circuit configured to obtain at least one magnetic power loss parameter scaling coefficient.

[0064] According to another embodiment, the at least one magnetic power loss parameter scaling factor includes a magnetic power loss parameter scaling factor received from a transmitter.

[0065] According to another embodiment, the wireless power transmitting device includes a wireless power transmitting device of a given transmitter model, and the magnetic power loss parameter scaling factor is a ratio of 1) a receiver coil loss factor determined by pairing a transmitter of the given transmitter model to a reference receiver and 2) a receiver coil loss factor determined by pairing a reference transmitter to a reference receiver.

[0066] According to another embodiment, the wireless power transmitting device includes a wireless power transmitting device of a given transmitter model, and the magnetic power loss parameter scaling factor is a ratio of 1) a friendly metal loss factor determined by pairing a transmitter of the given transmitter model to a reference receiver, and 2) a friendly metal loss factor determined by pairing a reference transmitter with a reference receiver.

[0067] According to another embodiment, the wireless power receiving device includes a wireless power receiving device of a given receiver model, and the magnetic power loss parameter scaling factor is a ratio of 1) a transmitter coil loss factor determined by pairing a receiver of the given receiver model to a reference transmitter and 2) a transmitter coil loss factor determined by pairing the reference receiver to a reference transmitter.

[0068] According to another embodiment, the control circuitry is configured to wirelessly transmit the magnetic power loss parameter scaling factor to the wireless power transmitting device using the wireless power receiving coil.

[0069] According to another embodiment, the control circuitry is configured to determine the receiver power loss value using a magnetic power loss parameter scaling factor.

[0070] According to another embodiment, the magnetic power loss parameter scaling factor comprises a magnetic power loss parameter scaling factor received from a wireless power transmitting device using a wireless power receiving coil.

[0071] According to one embodiment, there is provided a wireless power receiving device configured to obtain wireless power from a wireless power transmitting device, the wireless power receiving device including: a wireless power receiving circuit having a wireless power receiving coil configured to receive a wireless power signal; a rectifier configured to rectify an AC signal from the wireless power receiving coil and generate a corresponding DC power; and a control circuit configured to estimate a wireless power receiver power loss value using a magnetic power loss parameter scaling factor and transmit the estimated wireless power receiver power loss value to the wireless power transmitting device.

[0072] According to another embodiment, the magnetic power loss parameter scaling factor comprises a magnetic power loss parameter scaling factor received from a wireless power transmitting device.

[0073] According to another embodiment, the control circuitry is configured to store the additional magnetic power loss parameter scaling factor and configured to transmit the additional magnetic power loss parameter scaling factor to the wireless power transmitting device.

[0074] The above is merely illustrative and various modifications may be made to the described embodiments. The above embodiments may be implemented individually or in any combination. In particular, there may be significant flexibility in terms of which receiver loss coefficients and which scaling coefficients are stored in RX or TX and which are swapped between TX and RX during run-time. The particular choice of which coefficients and scaling coefficients are swapped is not a limitation.

Claims

1. 1. A wireless power transmitting device configured to provide wireless power to a wireless power receiving device, comprising: a wireless power transmission circuit having a wireless power transmission coil configured to transmit a wireless power signal; A control circuit comprising: a control circuit configured to estimate a foreign object power loss value based at least in part on a scaling factor exchanged between the wireless power receiving device and the wireless power transmitting device, the scaling factor being determined using characterization information from measurements made with at least one of a reference transmitter and a reference receiver; A wireless power transmission device comprising:

2. The wireless power transmitting device of claim 1 , wherein the control circuitry is further configured to determine whether to present a user interface affordance based at least in part on the estimated foreign object power loss value.

3. The control circuit, determining whether a foreign object is present based at least in part on the estimated foreign object power loss value; The wireless power transmitting device of claim 1 , further configured to:

4. 2. The wireless power transmitting device of claim 1, wherein the wireless power receiving device comprises a wireless power receiving device of a given receiver model, and the scaling factor is a ratio of 1) a transmitter coil loss factor determined by pairing a receiver of the given receiver model to a reference transmitter, and 2) a transmitter coil loss factor determined by pairing a reference receiver to a reference transmitter.

5. 2. The wireless power transmitting device of claim 1, wherein the control circuit is configured to wirelessly exchange the scaling factor upon pairing of the wireless power transmitting device with the wireless power receiving device before the wireless power transmitting circuit begins normal power transmission operation.

6. 6. The wireless power transmitting device of claim 5, wherein the control circuitry is configured to estimate the foreign object power loss value by determining: 1) a power input value; 2) a power output value; 3) a transmitter power loss value; and 4) a receiver power loss value.

7. The wireless power transmitting device of claim 6 , wherein the receiver power loss value is determined based at least in part on a receiver coil loss value and a friendly metal loss value.

8. The wireless power transmitting device of claim 6 , wherein the control circuitry is configured to obtain the receiver power loss value from the wireless power receiving device.

9. 2. The wireless power transmitting device of claim 1, wherein the wireless power receiving device comprises a wireless power receiving coil, and the scaling factor is used to scale a transmitter coil loss factor to reflect a dependence of power loss by the wireless power transmitting coil on magnetic coupling between the wireless power transmitting coil and the wireless power receiving coil.

10. 1. A wireless power receiving device configured to obtain wireless power from a wireless power transmitting device, comprising: a wireless power receiving circuit having a wireless power receiving coil configured to receive a wireless power signal; a control circuit configured to obtain at least one scaling factor, the scaling factor being determined using characterization information from measurements made with at least one of a reference transmitter and a reference receiver; A wireless power receiving device comprising:

11. The wireless power receiving device of claim 10 , wherein the at least one scaling factor comprises a scaling factor received from the wireless power transmitting device.

12. 12. The wireless power receiving device of claim 11, wherein the wireless power transmitting device comprises a wireless power transmitting device of a given transmitter model, and the scaling factor is a ratio of 1) a receiver coil loss factor determined by pairing a transmitter of the given transmitter model to a reference receiver, and 2) a receiver coil loss factor determined by pairing a reference transmitter to a reference receiver.

13. 12. The wireless power receiving device of claim 11, wherein the wireless power transmitting device comprises a wireless power transmitting device of a given transmitter model, and the scaling factor is a ratio of 1) a friendly metal loss factor determined by pairing a transmitter of the given transmitter model to a reference receiver, and 2) a friendly metal loss factor determined by pairing a reference transmitter with a reference receiver.

14. 11. The wireless power receiving device of claim 10, wherein the wireless power receiving device comprises a wireless power receiving device of a given receiver model, and the scaling factor is a ratio of 1) a transmitter coil loss factor determined by pairing a receiver of the given receiver model to a reference transmitter, and 2) a transmitter coil loss factor determined by pairing a reference receiver to a reference transmitter.

15. The wireless power receiving device of claim 10 , wherein the control circuitry is configured to wirelessly transmit the scaling factor to the wireless power transmitting device using the wireless power receiving coil.

16. The wireless power receiving device of claim 10 , wherein the control circuitry is configured to use the scaling factor to determine a receiver power loss value.

17. The wireless power receiving device of claim 16 , wherein the scaling factor comprises a scaling factor received from the wireless power transmitting device using the wireless power receiving coil.

18. 1. A wireless power receiving device configured to obtain wireless power from a wireless power transmitting device, comprising: a wireless power receiving circuit having a wireless power receiving coil configured to receive a wireless power signal; a rectifier configured to rectify an AC signal from the wireless power receiving coil and generate a corresponding DC power; A control circuit comprising: Estimating a wireless power receiver power loss value using the scaling factor; a control circuit configured to transmit the estimated wireless power receiver power loss value to the wireless power transmitting device, the scaling factor being determined using characterization information from measurements made with at least one of a reference transmitter and a reference receiver; A wireless power receiving device comprising:

19. The wireless power receiving device of claim 18 , wherein the scaling factor comprises a scaling factor received from the wireless power transmitting device.

20. 20. The wireless power receiving device of claim 18, wherein the control circuitry is configured to store an additional scaling factor and to transmit the additional scaling factor to the wireless power transmitting device.

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