Power contract policy for wireless charging

Abstract

A wireless power transmitter may include an inverter that receives input power and generates an AC output voltage; a wireless power transmitter coil coupled to an AC output, the AC output magnetically coupled to a corresponding coil of the wireless power receiver; and a controller and a communication module. The controller and communication module may receive identification information from the wireless power receiver; receiving voltage information from the wireless power receiver; calculating a coupling factor with the wireless power receiver based at least in part on the received identification information and the received voltage information; calculating a power transfer level based on the calculated coupling factor; and negotiating a power contract with the wireless power receiver based at least in part on the calculated power transfer level.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 364,463, filed on May 10, 2022, entitled “POWER CONTRACT POLICY FOR WIRELESS CHARGING,” the disclosure of which is incorporated herein by reference in its entirety for all purposes. Background Art

[0003] Wireless power transfer ("WPT"), such as inductive power transfer ("IPT"), can be used to provide power for charging various battery-powered electronic devices. One application where WPT usage is increasing is in the consumer electronics space surrounding devices such as mobile phones (i.e., smartphones) and their accessories (e.g., wireless earphones, smart watches, etc.), as well as tablets and other types of portable computers and their accessories (e.g., styluses, etc.). Summary of the invention

[0004] A wireless power transmitter may include: an inverter that receives input power and generates an AC output voltage; a wireless power transmitter coil that is coupled to an AC output that is magnetically coupled to a corresponding coil of a wireless power receiver; and a controller and a communication module. The controller and the communication module may receive identification information from the wireless power receiver; receive voltage information from the wireless power receiver; calculate a coupling factor with the wireless power receiver based at least in part on the received identification information and the received voltage information; calculate a power transfer level based on the calculated coupling factor; and negotiate a power contract with the wireless power receiver based at least in part on the calculated power transfer level.

[0005] The identification information may specifically identify the wireless power receiver. The identification information may identify the wireless power receiver as a member of a class of wireless power receivers.

[0006] The coupling factor can be calculated according to the following equation:

[0007]

[0008] Where k is the coupling factor, Vrect is the rectifier voltage that is at least a part of the received voltage information, Vinv is the input DC voltage of the inverter, VCTXpp is the peak voltage across the transmitter tuning capacitor, and C0 and C1 are fitting coefficients.

[0009] This power transfer level can be calculated according to the following equation:

[0010] P target=k 2 ·C pwr

[0011] Where Ptarget is the power that can be delivered to the receiver, k is the coupling factor, and Cpwr is a constant for the transmitter / receiver combination determined by the controller at least in part based on the received receiver identification information. Cpwr is stored in a memory of the controller and retrieved based at least in part on the received receiver identification information. Cpwr may be included in the received receiver identification information. Cpwr may be calculated according to the following formula:

[0012]

[0013] where Prect_max is the maximum total power level required by the receiver, RXLoss is the power loss in the receiver, and kmin is the minimum coupling coefficient corresponding to the maximum acceptable displacement between the transmitter and the receiver.

[0014] A method for negotiating a wireless power delivery contract with a wireless power receiver performed by a wireless power transmitter may include: receiving identification information from the wireless power receiver via a wireless communication link; receiving voltage information from the wireless power receiver via a wireless communication link; calculating a coupling factor with the wireless power receiver based at least in part on the received identification information and the received voltage information using a processor of the wireless power transmitter; calculating a power transfer level based on the calculated coupling factor using the processor; and negotiating the wireless power delivery contract based at least in part on the calculated power transfer level.

[0015] The identification information may specifically identify the wireless power receiver. The identification information identifies the wireless power receiver as a member of a class of wireless power receivers.

[0016] The coupling factor can be calculated according to the following equation:

[0017]

[0018] Where k is the coupling factor, Vrect is the rectifier voltage as the received voltage information, Vinv is the input DC voltage of the inverter, VCTXpp is the peak voltage across the transmitter tuning capacitor, and C0 and C1 are fitting coefficients.

[0019] This power transfer level can be calculated according to the following equation:

[0020] P target =k 2 ·C pwr

[0021] Where Ptarget is the power that can be delivered to the receiver, k is the coupling factor, and Cpwr is a constant for the transmitter / receiver combination stored in the memory of the controller and selected based on the received receiver identification information. Cpwr is stored in the memory of the controller and retrieved based at least in part on the received receiver identification information. Cpwr may be included in the received receiver identification information. Cpwr may be calculated according to the following formula:

[0022]

[0023] where Prect_max is the maximum total power level required by the receiver, RXLoss is the power loss in the receiver, and kmin is the minimum coupling coefficient corresponding to the maximum acceptable displacement between the transmitter and the receiver.

[0024] A wireless power transmission device may include: a wireless power coil, which is magnetically coupled to a corresponding coil of another wireless power transmission device; and a controller and a communication module, which receive identification information from the other wireless power transmission device, receive voltage information from the other wireless power transmission device, calculate a coupling factor with the other wireless power transmission device based at least in part on the received identification information and the received voltage information, calculate a power transfer level based on the calculated coupling factor, and negotiate a power contract with the other wireless power transmission device based at least in part on the calculated power transfer level.

[0025] The identification information may specifically identify the other wireless power transmission device. The identification information may identify the other wireless power transmission device as a member of a class of wireless power transmission devices.

[0026] The coupling factor is calculated according to the following equation:

[0027]

[0028] Where k is a coupling factor, Vrect is the rectifier voltage of the wireless power receiver, Vinv is the DC input voltage of the inverter of the wireless power transmitter, VCTXpp is the peak voltage across the transmitter tuning capacitor, and C0 and C1 are fitting coefficients. The wireless power transmission device may be a wireless power receiver, and the other wireless power transmission device is a wireless power transmitter, and Vinv and VCTXpp are at least a portion of the received voltage information. The power transfer level is calculated according to the following equation:

[0029] P target =k 2 ·C pwr

[0030] Where Ptarget is the power that can be delivered to the wireless power receiver, k is the coupling factor, and Cpwr is a constant for the transmitter / receiver combination stored in the memory of the controller and the communication module and selected based on the received identification information. Cpwr is stored in the memory of the controller and retrieved based at least in part on the received identification information. Cpwr may be included in the received identification information. Cpwr may be calculated according to the following formula:

[0031]

[0032] where Prect_max is the maximum total power level required by the receiver, RXLoss is the power loss in the receiver, and kmin is the minimum coupling coefficient corresponding to the maximum acceptable displacement between the transmitter and the receiver.

[0033] This power transfer level can be calculated according to the following equation:

[0034] P target =k 2 ·C pwr

[0035] Where Ptarget is the power that can be delivered to the wireless power receiver, k is the coupling factor, and Cpwr is a constant for the transmitter / receiver combination stored in the memory of the controller and the communication module and selected based on the received identification information. Cpwr is stored in the memory of the controller and retrieved based at least in part on the received identification information. Cpwr may be included in the received identification information. Cpwr may be calculated according to the following formula:

[0036]

[0037] where Prect_max is the maximum total power level required by the receiver, RXLoss is the power loss in the receiver, and kmin is the minimum coupling coefficient corresponding to the maximum acceptable displacement between the transmitter and the receiver. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A block diagram of a wireless power transfer system is shown.

[0039] FIG. 2A to FIG. 2C Various configurations of wireless power transfer systems are shown.

[0040] Figure 3 A table showing power transfer levels for a wireless power transfer system.

[0041] Figure 4 A simplified schematic diagram of a wireless power transfer system is shown.

[0042] Figure 5 A process for determining a target power transfer level in a wireless power transfer system is shown.

[0043] Figure 6 A table showing power transfer levels for a wireless power transfer system.

[0044] Figure 7 A process for calculating wireless power transfer levels in a wireless power transfer system is shown. DETAILED DESCRIPTION

[0045] In the following description, for the purpose of explanation, many specific details are set forth in order to provide a thorough understanding of the disclosed concepts. As part of this description, some of the drawings in the drawings of the present disclosure represent structures and devices in block diagram form for simplicity. For the sake of clarity, not all features of actual implementations are described in the present disclosure. In addition, the language used in the present disclosure is selected for readability and instructional purposes and has not been selected to describe or limit the disclosed subject matter. Instead, the attached claims are intended for this purpose.

[0046] Various embodiments of the disclosed concepts are illustrated by way of example, and are not limited to individual drawings, in which similar reference numerals indicate similar elements. For simplicity and clear illustration, reference numerals are repeated in different drawings to indicate corresponding or similar elements, where appropriate. In addition, many specific details are shown in order to provide a full understanding of the specific implementation described herein. In other cases, methods, procedures, and components are not described in detail to avoid blurring the related functions described. Mentioning "one", "a kind of" or "another" embodiment in this disclosure is not necessarily the same or different embodiments, and this means at least one. A given drawing may be used to illustrate more than one embodiment or more than one type of features of the present disclosure, and all elements in the drawings may not be required for a given embodiment or type. When provided in the drawings, the reference numerals refer to the same element throughout several drawings, but they may not be repeated in each drawing. Unless otherwise specified, the drawings are not drawn to scale, and the proportions of certain components may be enlarged to better illustrate the details and features of the present disclosure.

[0047] Figure 1A simplified block diagram of a wireless power transmission system 100 is shown. The wireless power transmission system includes a power transmitter (PTx) 110 that wirelessly transmits power to a power receiver (PRx) 120, such as via inductive coupling 130. The power transmitter 110 can receive input power, which is converted by an inverter 114 into an AC voltage having specific voltage and frequency characteristics. The inverter 114 can be controlled by a controller / communication module 116, which operates as further described below. In various embodiments, the inverter controller and the communication module can be implemented in a common system (such as a system based on a microprocessor, a microcontroller, etc.). In other embodiments, the inverter controller can be implemented by a separate controller module and a communication module with a communication device therebetween. The inverter 114 can be constructed using any suitable circuit topology (e.g., full bridge, half bridge, etc.) and can be implemented using any suitable semiconductor switching device technology (e.g., MOSFET, IGBT, etc. manufactured using silicon, silicon carbide, or gallium nitride devices).

[0048] The inverter 114 can deliver the generated AC voltage to the transmitter coil 112. In addition to allowing magnetic coupling to the wireless coil of the receiver, Figure 1 The illustrated transmitter coil block 112 may include tuning circuits (such as additional inductors and capacitors) that facilitate operation of the transmitter under different conditions (such as different degrees of magnetic coupling to the receiver, different operating frequencies, etc.). The wireless coil itself can be constructed in a variety of different ways. In some embodiments, the wireless coil can be formed as a winding of wire around a suitable bobbin. In other embodiments, the wireless coil can be formed as a trace on a printed circuit board. Other arrangements are also possible and can be used in conjunction with the various embodiments described herein. The wireless transmitter coil may also include a magnetically permeable material (e.g., ferrite) core that is configured to affect the flux pattern of the coil in a manner suitable for a particular application. The teachings herein may be applied in conjunction with any of a variety of transmitter coil arrangements suitable for a given application.

[0049] The PTx controller / communication module 116 may monitor the transmitter coil and use information derived therefrom to control the inverter 114 to suit a given situation. For example, the controller / communication module may be configured to operate the inverter 114 at a given frequency or output voltage depending on the particular application. In some embodiments, the controller / communication module may be configured to receive information from the PRx device and control the inverter 114 accordingly. This information may be received via the power transmission coil (i.e., in-band communication) or may be received via a separate communication channel (not shown, i.e., out-of-band communication). For in-band communication, the controller / communication module 116 may detect and decode signals (such as voltage, frequency, or load changes) imposed on the magnetic link by the PRx to receive information, and may command the inverter to modulate the delivered power by manipulating various parameters of the generated voltage (such as voltage, frequency, etc.) to transmit information to the PRx. In some embodiments, the controller / communication module may be configured to employ frequency shift keying (FSK) communication to convey data to the PRx, in which the frequency of the inverter signal is modulated. The controller / communication module 116 may be configured to detect amplitude shift keying (ASK) communications or load modulation based communications from the PRx. In either case, the controller / communication module 126 may be configured to vary the current drawn on the receiver side to manipulate the waveform seen on the Tx coil, thereby delivering information from the PRx to the PTx. For out-of-band communications, additional modules may be provided that allow communication between the PTx and PRx, such as WiFi, Bluetooth, or other radio links, or any other suitable communication channel.

[0050] As described above, the controller / communication module 116 can be a single module, for example, disposed on a single integrated circuit, or can be constructed from a plurality of modules / devices disposed on different integrated circuits or a combination of integrated circuits and discrete circuits having analog components and digital components. The teachings herein are not limited to any particular arrangement of controller / communication circuits.

[0051] The PTx device 110 may optionally include other systems and components, such as a separate communication ("comms") module 118. In some embodiments, the communication module 118 may communicate with a corresponding module tag in the PRx via a power transfer coil. In other embodiments, the communication module 118 may communicate with a corresponding module using a separate physical channel 138.

[0052] As mentioned above, the wireless power transfer system also includes a wireless power receiver (PRx) 120. The wireless power receiver may include a receiver coil 122 that may be magnetically coupled 130 to the transmitter coil 112. As discussed above, the transmitter coil 112, Figure 1The illustrated receiver coil block 122 may include tuning circuits (such as additional inductors and capacitors) that facilitate operation of the transmitter under different conditions (such as different degrees of magnetic coupling to the receiver, different operating frequencies, etc.). The wireless coil itself can be constructed in a variety of different ways. In some embodiments, the wireless coil can be formed as a wire winding around a suitable bobbin. In other embodiments, the wireless coil can be formed as a trace on a printed circuit board. Other arrangements are also possible and can be used in conjunction with the various embodiments described herein. The wireless receiver coil may also include a magnetically permeable material (e.g., ferrite) core that is configured to affect the flux pattern of the coil in a manner suitable for a particular application. The teachings herein may be applied in conjunction with any of a variety of receiver coil arrangements suitable for a given application.

[0053] The receiver coil 122 outputs an AC voltage induced therein by magnetic induction via the transmitter coil 112. The output AC voltage may be provided to a rectifier 124, which provides a DC output power to one or more loads associated with the PRx device. The rectifier 124 may be controlled by a controller / communication module 126, which operates as further described below. In various embodiments, the rectifier controller and the communication module may be implemented in a common system (such as a system based on a microprocessor, a microcontroller, etc.). In other embodiments, the rectifier controller may be implemented by a separate controller module and a communication module with a communication device therebetween. The rectifier 124 may be constructed using any suitable circuit topology (e.g., full bridge, half bridge, etc.) and may be implemented using any suitable semiconductor switching device technology (e.g., MOSFETs, IGBTs, etc. manufactured using silicon, silicon carbide, or gallium nitride devices).

[0054] The PRx controller / communication module 126 may monitor the receiver coil and use information derived therefrom to control the rectifier 124 to suit a given situation. For example, the controller / communication module may be configured to cause the rectifier 124 to provide a given output voltage depending on the particular application. In some embodiments, the controller / communication module may be configured to transmit information to the PTx device to effectively control the power delivered to the receiver. This information may be sent via the power transmission coil (i.e., in-band communication) or may be sent via a separate communication channel (not shown, i.e., out-of-band communication). For in-band communication, the controller / communication module 126 may, for example, modulate the load current or other electrical parameters of the received power to transmit information to the PTx. In some embodiments, the controller / communication module 126 may be configured to detect and decode signals (such as voltage, frequency, or load changes) imposed on the magnetic link by the PTx to receive information from the PTx. In some embodiments, the controller / communication module 126 may be configured to receive frequency shift keying (FSK) communications in which the frequency of the inverter signal has been modulated to convey data to the PRx. The controller / communication module 126 may be configured to generate amplitude shift keying (ASK) communications or load modulation based communications from the PRx. In either case, the controller / communication module 126 may be configured to vary the current drawn on the receiver side to manipulate the waveform seen on the Tx coil, thereby delivering information from the PRx to the PTx. For out-of-band communications, additional modules may be provided that allow communication between the PTx and PRx, such as WiFi, Bluetooth, or other radio links, or any other suitable communication channel.

[0055] As described above, the controller / communication module 126 can be a single module, for example, disposed on a single integrated circuit, or can be constructed from a plurality of modules / devices disposed on different integrated circuits or a combination of integrated circuits and discrete circuits having analog components and digital components. The teachings herein are not limited to any particular arrangement of controller / communication circuits.

[0056] The PRx device 120 may optionally include other systems and components, such as a communication module 128. In some embodiments, the communication module 128 may communicate with a corresponding module in the PTx via a power transmission coil. In other embodiments, the communication module 128 may communicate with a corresponding module or tag using a separate physical channel 138.

[0057] Many variations and enhancements of the wireless power transmission system 100 described above are possible, and the following teachings apply to any of such variations and enhancements.

[0058] Wireless power transmission as described above depends on the degree of electromagnetic coupling between PTx and PRx. For example, in an inductive charging system, the transmitter coil 112 and the receiver coil 122 can be considered as loosely coupled transformers. Therefore, the relative position of PTx and PRx can affect the degree of magnetic coupling between PTx and PRx, which in turn can affect the power transmission capability of the system. Figure 2A A simplified diagram of a PTx (110)-PRx (120) system is shown. The two devices are shown in a plan view (upper portion of the figure) and an edge cross-sectional view (lower portion of the figure). The PTx device 110 includes a transmitter coil 112, and the PRx device 120 includes a receiver coil 122. In some embodiments, the PTx device 110 can be a wireless charging plate, pad, or stand (or other wireless power transmission device), and the PRx device 120 can be a mobile phone, tablet computer, smart watch (or other wireless power receiver device). Although the respective devices are depicted as having a generally rectangular shape with a generally circular charging coil, it should be understood that other configurations are possible.

[0059] Figure 2B The "optimal" alignment of PTx 110 and PRx 120 is shown. Figure 2B In the embodiment of the present invention, these devices are aligned horizontally (as depicted in plan view) and vertically and as close as possible (as shown in cross-section view). In this context, horizontal and vertical are used as terms of convenience only, and the actual orientation of the system may vary, and the following description applies to systems in any such orientation, although "horizontal" and "vertical" will continue to be used for clarity of context. Figure 2C The devices are shown with a slight misalignment. More specifically, there is a radial displacement "r", which can be understood by noting that the centers of coils 112 and 122 no longer coincide in the plan view. Such radial displacement can be caused by any number of things, such as, for example, a user slightly misaligning the phone with the charging pad. In addition, there is a vertical displacement "z", which can be understood by noting the separation between the PTx device 110 and the PRx device 120 in the cross-sectional view. This vertical displacement can also be caused by any number of things, such as, a phone enclosed in a housing or cover. The cross-sectional view also shows a lateral / radial displacement. It should be understood that in some cases, there may be only radial displacement or only vertical displacement.

[0060] In any case, the above-mentioned offset can reduce the degree of magnetic coupling between the PTx and PRx devices. The reduced magnetic coupling can limit the amount of power that can be delivered from the PTx 110 to the PRx 120 while remaining within the performance limits of the PTx device 110. More specifically, the reduced coupling between the PTx 110 and the PRx 120 reduces the portion of the power sent from the PTx 110 that is received by the PRx 120. The PTx 110 has a maximum operating voltage and a maximum current that can be supplied, effectively resulting in a maximum power transfer level. In addition, in some applications, the PTx controller 116 may become unstable, thereby attempting to supply a power level requested by the PRx controller 126 that is impossible / unfeasible given the degree of coupling. Therefore, as the coupling between the PTx 110 and the PRx 120 is reduced, the PTx may not be able to supply the power level requested by the PRx 120. In some such cases, it may be desirable for the PTx 110 and PRx 120 to negotiate a power contract that specifies the power levels that the PTx can supply and that the PRx is expected to receive.

[0061] Such a power contract may be based at least in part on an estimate of the maximum available power transfer from the PTx 110 to the PRx 120, based on the system constraints imposed by the degree of coupling therebetween. One way to implement such an estimate is based on a measurement of the voltage gain from the PTx 110 to the PRx 120. More specifically, the PTx 110 and PRx 120 may be operated under various predetermined fixed load conditions, and the PTx 110 may be configured to provide a power contract to the PRx 120 by providing an inverter output voltage Vinv ( Figure 4 ) (i.e., the input voltage of the inverter 114) divided by the rectifier output voltage Vrect ( Figure 4 ) (i.e., the rectified voltage after the rectifier) ​​to calculate the gain for that load condition. In some cases, the corresponding load condition may be determined by an industry standard specification or by negotiation / agreement between devices. In any case, the negotiated power contract may include power targets or limits as a function of these estimated voltage gains.

[0062] Figure 3A table 301 is shown which plots estimated power transfer levels for different values ​​of radial offset (r) and vertical offset (z) for an exemplary embodiment. It should be understood that these values ​​are merely exemplary and that different values ​​may be calculated for different systems having different physical, electrical, and magnetic properties. The estimated power transfer level may be in Watts, and the radial offset may be a distance measured in millimeters. For values ​​greater than or equal to a high power transfer level (e.g., 15W), an "H" is presented. For values ​​less than or equal to a low power transfer level (e.g., 5W), an "L" is presented. For values ​​between these two thresholds, an "I" (for intermediate values) is presented. In some cases, the estimated power may be negative (a meaningless result), in which case "-ve" is indicated. Thus, at a radial / vertical offset of 0,0, the estimated power delivery capability may be high (e.g., 28W, which is greater than the 15W power delivery level), drops to -30W (a meaningless negative value presented as "-ve") at a radial offset of 8mm, and drops to -15W (another meaningless negative value presented as "-ve") at a vertical offset of 6mm. It should be noted that the negative values ​​are produced by a power estimation technique that relies on the product of voltage gains determined under different load conditions. More specifically, if one of the measured voltage gains is negative, it will produce a negative power delivery level, which is somewhat meaningless.

[0063] To address these and other inaccuracies of voltage gain-based estimation methods, Figure 3 Table 302 of FIG. 301 shows target power levels that may be set based on the estimated power calculations of Table 301. In general, for values ​​greater than or equal to a high power transfer level (e.g., 15W), the power target may be set to a high power transfer level (designated “H”), which may be the rated power level of the PTx 110. For estimated power transfer capabilities less than a low power transfer level (e.g., 5W), the power target may be set to a low power transfer level (designated “L”), which may be a minimum power transfer target specified by an industry standard. The power transfer target level may also be well below the maximum capability of the PTx 110 so that it does not cause controller instability or other operational issues. For intermediate power transfer estimates, the power contract may be set at one or more predefined intermediate levels (designated “I”). Each of the values ​​provided is merely an example, and any suitable power level may be used depending on the particular implementation.

[0064] As briefly mentioned above, power estimation techniques based on voltage gain measured under different load conditions may have accuracy issues. In addition, performing tests under various load conditions may also be time consuming, which may undesirably extend the startup time between when the PRx device is placed on the PTx and when full power level wireless transmission begins. In addition, gain measurements may be subject to many inaccuracies due to noise, etc. Therefore, it may be preferable to provide a power estimate based on a direct measurement of the coupling factor "k" ( Figure 4 ).

[0065] Figure 4 A partially simplified electrical schematic diagram of a wireless power transfer system including a PTx 110 is shown, represented by an inverter input voltage Vinv applied to an inverter bridge (e.g., full bridge, half bridge, etc.). A PRx 120 includes a transmit coil 112 / inductor LTx, a receive coil 122 / inductor LRx, a tuning capacitor CRx / 423, a rectifier 124, and an output load 429 represented by a resistor Prect. Figure 4 Also included in 4 are resistors RLRx / 422a, RCRx / 423a, and RPAR / 424a, which are not actual discrete resistors, but are inherent resistances corresponding to the receive coil 122, the tuning capacitor 423, and other parasitic losses of the system. Therefore, the received power PRx / 442 can be considered to include two components: Prect443, which is the power delivered to the load Rrect / 429; and the power loss RXLoss / 441 associated with the parasitic resistance.

[0066] The power transfer capability of this type of wireless power transfer system can be expressed as follows:

[0067] P Rx_target =k 2 ·C pwr

[0068] Where k is the coupling factor between the transmitter and the receiver, and Cpwr is a characteristic of the receiver that can be determined as described below. For a given degree of coupling, a higher value of Cpwr may result in a target power calculation that is higher than the receiver's requirements. Similarly, a lower Cpwr may result in a target power calculation that is lower than the receiver's requirements. Therefore, to ensure adequate power delivery, a "worst case" may be used to determine Cpwr, i.e., the relative position between the PTx 110 and the PRx 120 that has the lowest acceptable coupling, i.e., the minimum coupling that still guarantees the specified power transfer level. Therefore:

[0069]

[0070] Where Cpwr is the required power factor to guarantee the maximum power level targeted during power negotiation, Prect_max is the maximum total power level required by the receiver, RXLoss is the power loss in the receiver (discussed above), and kmin is the minimum coupling factor, typically corresponding to the maximum acceptable displacement between PTx 110 and PRx 120. As described above, this Cpwr factor in the above PRx_target calculation is a characteristic of each receiver, which may have different electrical and magnetic characteristics. Since the transmitter can use this value to calculate the target power level, the transmitter can have an access Cpwr for the receiver. In some cases, the transmitter can be programmed with Cpwr values ​​for various compatible receivers initially or via updates. In other cases, as part of the initialization phase, the receiver can provide its Cpwr value to the transmitter.

[0071] In some applications, Cpwr may be constant for a particular transmitter / receiver device combination. In addition, its three constituent elements (Prect_max, RXLoss, and kmin) may also be constant for a particular receiver and transmitter device, respectively. In other words, Cpwr and its constituent factors may be determined as a function of the physical, electrical, and magnetic properties of the construction of a particular device. Therefore, to facilitate power contract negotiation, the PTx 110 may store or otherwise access one or more Cpwr values ​​corresponding to one or more receivers or receiver types / categories. In either case, as part of initialization / power contract negotiation, the PTx 110 may identify the PRx 120 with which it is communicating and use the appropriate stored Cpwr value (or its constituent factors) to perform power estimation as described herein. In addition, or alternatively, the PRx 120 may store its own (P rect_max +R XLoss ) value and one or more kmin values ​​corresponding to one or more transmitters or transmitter types. Then, as part of the initialization / power contract negotiation process, the PRx 120 may provide its own (P rect_max +R XLoss ) value or an appropriate Cpwr value. Collectively or individually, this information may be considered receiver identification information, as it may provide the transmitter with appropriate characteristics of the receiver to allow an appropriate power contract to be established.

[0072] Figure 5A complete exemplary process 501 for calculating a power contract target power value for a system 502 using the principles described above is shown. Only certain parts of the method may be performed during the PTx / PRx initialization / negotiation process, as some parts may only be done once as part of the design / calibration / configuration of the respective receiver device and / or transmitter device. Table 503 represents a table of power levels, which is similar to the above with respect to Figure 3 The described tables are similar. In box 504, a designated area of ​​the design for maximum power delivery may be determined. As an example, it may be desirable to ensure maximum power delivery within a 2 mm radial offset and / or a 2 mm vertical offset from perfect alignment. Then, in box 505, the minimum coupling factor kmin that will allow this power transfer level may be determined. Similarly, in box 506, the worst-case rectifier losses may be determined. In box 507, the minimum coupling factor and the worst-case losses may be used to calculate the Cpwr value using the above formula. The Cpwr value (an example of receiver identification information) may be provided to the transmitter via programming (including initial configuration or software / firmware update), communication, or other suitable techniques as described above. Finally, in box 508, the transmitter may calculate the target power for different positions (i.e., different radial and / or vertical offsets) by using the Prect_target formula discussed above.

[0073] Figure 6 A first table 601 of estimated power values ​​using the above calculation technique is shown. Figure 3 301, estimated power transfer levels for different values ​​of radial offset (r) and vertical offset (z) are used for an exemplary embodiment. It should be understood that these values ​​are merely exemplary and that different values ​​may be calculated for different systems having different physical, electrical, and magnetic properties. The estimated power transfer level may be in units of Watts, and the radial offset may be a distance measured in millimeters. Thus, at a radial / vertical offset of 0,0, the estimated power transfer capability may be 25W (designated "H" because it is higher than the exemplary high power level of 15W), dropping to 8W at a radial offset of 8mm (designated "I" because it is lower than the exemplary high power level of 15W but higher than the exemplary low power level of 5W), and dropping to 6W at a vertical offset of 6mm (designated "I" because it is lower than the exemplary high power level of 15W but higher than the exemplary low power level of 5W). It should be noted that these values ​​are comparable to those described above with reference to FIG. Figure 3 Those values ​​calculated by the discussed alternative calculation based on voltage gain are more accurate and more conservative.

[0074] Figure 6Also shown is a second table 602 of power contract target power levels, which may optionally be set based on the estimated power calculations of table 601. In general, for values ​​greater than a high power level (e.g., 15W), the power target may be set to 15W (designated "H"), which may be the nominal power level of the PTx 110. For estimated power transfer capabilities less than a low power level (e.g., 5W), the power target may be set to 5W (designated "L"), which may be the minimum power transfer target specified by an industry standard. This power transfer target level may also be well below the maximum capability of the PTx 110 so that it does not cause controller instability or other operational issues. For intermediate power transfer estimates, the power contract may be set at one or more predefined intermediate levels (designated "I"), as shown in table 602 and generally as discussed above.

[0075] The above power estimation technique requires knowledge of the coupling factor "k" between PTx 110 and PRx 120. Various techniques may be used to obtain this factor. In one embodiment, it may be calculated according to the following formula:

[0076]

[0077] where kest is the calculated (estimated) coupling factor and Vrect is the rectifier voltage measured during startup ( Figure 4 ), Vinv is the inverter input DC voltage on the transmitter side, VCTXpp is the peak voltage across the transmitter tuning capacitor in series with the power transmission winding (not shown), and C0 and C1 are fitting coefficients empirically determined for a given range of coupling factors. Because this depends on voltage measurements or values ​​made under only a single operating condition, this process can be performed faster than the multi-load condition voltage gain measurement described above.

[0078] Figure 7 A flow chart 700 of a power contract negotiation process that may be performed by a PTx 110 and / or a PRx 120 is shown. More specifically, the calculations may be performed by a processor that is part of a controller 116 or 126 using data stored in a corresponding memory, hard-coded into a corresponding device, or received from a paired device. Beginning at block 751, a device (PTx or PRx) may receive identification information from a paired device (PRx or PTx, respectively). The identification information may be a simple identifier of the device class to which the device or paired object belongs, thereby allowing the receiving device to look up a stored Cpwr value or a constituent factor of a paired device. For example, a transmitter (PTx) may receive identification information from a receiver (PRx) that allows the transmitter to look up a Cpwr value or a constituent factor corresponding to a receiver device (P rect_max +R XLoss) value. Alternatively, the receiver (PRx) may receive identification information from the transmitter (PTx) that allows the receiver to look up the Cpwr value or kmin value corresponding to the transmitter device. In another alternative, the paired device may directly provide its composition factor (P for PRx). rect_max +R XLoss Or kmin for PTx). In any case, the receiving device can determine the appropriate Cpwr value from the identification information.

[0079] In block 752, a device (PTx or PRx) may receive voltage information from a paired device. If the paired device is a PRx device, the voltage information may be the rectifier voltage Vrect, or if the paired device is a PTx device, the voltage information may be the inverter voltage and the transmitter tuning capacitor peak-to-peak voltage. In either case, the voltage information may be combined with local voltage measurements to calculate (or estimate) a coupling factor "k" between the devices (block 753). (In either case, the device performing the calculation may also have stored any fitting coefficients required for the calculation.) Based on the k value and the previously determined Cpwr value, the power target for the negotiated power contract may be calculated as described above (block 754).

[0080] The foregoing describes an exemplary embodiment of a wireless power transfer system that employs coupling-based power transfer estimation and power supply contract negotiation. Such a system can be used in a variety of applications, but can be particularly advantageous when used in conjunction with a wireless power transfer system for personal electronic devices, such as mobile computing devices (e.g., laptop computers, tablet computers, smart phones, etc.) and their accessories (e.g., wireless headphones, stylus pens and other input devices, etc.) and wireless charging accessories (e.g., charging pads, pads, stands, etc.). Although many specific features and various embodiments have been described, it should be understood that the various features and embodiments may be combined into various arrangements in a particular implementation unless otherwise indicated as mutually exclusive. Therefore, the various embodiments described above are provided by way of example only and should not be construed as limiting the scope of the present disclosure. Various modifications and changes may be made to the principles and embodiments herein without departing from the scope of the present disclosure and without departing from the scope of the claims.

[0081] The foregoing describes an exemplary embodiment of a wireless power transmission system capable of transmitting certain information between a PTx and a PRx in the system. The present disclosure contemplates that this information transfer improves the ability of devices to provide wireless power signals to each other in an efficient manner to facilitate battery charging, such as by sharing the power handling capabilities of the devices with each other. Entities implementing the present technology should be careful to ensure compliance with established privacy policies and / or privacy practices to the extent that any sensitive information is used in a particular implementation. In particular, such entities will be expected to implement and consistently apply privacy practices that are generally recognized as meeting or exceeding industry or government requirements for maintaining user privacy. Implementers should inform users where personally identifiable information is expected to be sent in the wireless power transmission system, and allow users to "opt-in" or "opt-out" participation. For example, if a power transmitter is configured to poll for sensitive information from a power receiver, such information may be presented to the user when the user places the device onto the power transmitter.

[0082] Once the data is no longer needed, risks can be minimized by limiting data collection and data deletion. In addition, and when applicable, data de-identification can be used to protect the privacy of users. For example, a device identifier can be partially masked to convey the power characteristics of the device without uniquely identifying the device. De-identification can be facilitated by removing identifiers, controlling the amount or specificity of stored data (e.g., collecting location data at a city level rather than an address level), controlling how data is stored (e.g., aggregating data across users), and / or other methods such as differential privacy when appropriate. Robust encryption can also be used to reduce the possibility of communications between inductively coupled devices being spoofed.

Claims

1. A wireless power transmitter, the wireless power transmitter include: an inverter that receives input power and generates an AC output voltage; a wireless power transmitter coil coupled to an AC output magnetically coupled to a corresponding coil of a wireless power receiver; and A controller and a communication module, wherein the controller and the communication module: receiving identification information from the wireless power receiver; receiving voltage information from the wireless power receiver; calculating a coupling factor with the wireless power receiver based at least in part on the received identification information and the received voltage information; calculating a power transfer level based on the calculated coupling factor; as well as A power contract is negotiated with the wireless power receiver based at least in part on the calculated power transfer level. 2 . The wireless power transmitter according to claim 1 , wherein the identification information specifically identifies the wireless power receiver. 3 . The wireless power transmitter of claim 1 , wherein the identification information identifies the wireless power receiver as a member of a class of wireless power receivers.

4. The wireless power transmitter of claim 1 , wherein the coupling factor is calculated according to the following equation: Where k is the coupling factor, Vrect is the rectifier voltage that is at least a part of the received voltage information, Vinv is the input DC voltage of the inverter, VCTXpp is the peak voltage across the transmitter tuning capacitor, and C0 and C1 are fitting coefficients.

5. The wireless power transmitter of claim 1 , wherein the power transfer level is calculated according to the following equation: P target =k 2 ·C pwr Where Ptarget is the power that can be delivered to the receiver, k is the coupling factor, and Cpwr is a constant for a transmitter / receiver combination determined by the controller based at least in part on the received receiver identification information. 6 . The wireless power transmitter of claim 5 , wherein Cpwr is stored in a memory of the controller and retrieved based at least in part on the received receiver identification information. The wireless power transmitter of claim 5 , wherein Cpwr is included in the received receiver identification information.

8. The wireless power transmitter according to claim 5, wherein Cpwr is calculated according to the following formula: where Prect_max is the maximum total power level required by the receiver, RXLoss is the power loss in the receiver, and kmin is the minimum coupling coefficient corresponding to the maximum acceptable displacement between transmitter and receiver.

9. A method performed by a wireless power transmitter to negotiate a wireless power delivery contract with a wireless power receiver, the method include: receiving identification information from the wireless power receiver via a wireless communication link; receiving voltage information from the wireless power receiver via the wireless communication link; calculating, with a processor of the wireless power transmitter, a coupling factor with the wireless power receiver based at least in part on the received identification information and the received voltage information; calculating, with the processor, a power transfer level based on the calculated coupling factor; as well as The wireless power delivery contract is negotiated based at least in part on the calculated power transfer level.

10. The method of claim 9, wherein the identification information specifically identifies the wireless power receiver.

11. The method of claim 9, wherein the identification information identifies the wireless power receiver as a member of a class of wireless power receivers.

12. The method of claim 9, wherein the coupling factor is calculated according to the following equation: Where k is the coupling factor, Vrect is the rectifier voltage as the received voltage information, Vinv is the input DC voltage of the inverter, VCTXpp is the peak voltage across the transmitter tuning capacitor, and C0 and C1 are fitting coefficients.

13. The method of claim 9, wherein the power transfer level is calculated according to the following equation: P target =k 2 ·C pwr Where Ptarget is the power that can be delivered to the receiver, k is the coupling factor, and Cpwr is a constant available to the controller for the transmitter / receiver combination selected based on the received receiver identification information.

14. The method of claim 13, wherein Cpwr is stored in a memory of the controller and retrieved based at least in part on the received receiver identification information. The method of claim 13 , wherein Cpwr is included in the received receiver identification information.

16. The method of claim 13, wherein Cpwr is calculated according to the following formula: where Prect_max is the maximum total power level required by the receiver, RXLoss is the power loss in the receiver, and kmin is the minimum coupling coefficient corresponding to the maximum acceptable displacement between transmitter and receiver.

17. A wireless power transmission device, the wireless power transmission device include: a wireless power coil magnetically coupled to a corresponding coil of another wireless power transfer device; and A controller and a communication module, wherein the controller and the communication module: receiving identification information from the other wireless power transmission device; receiving voltage information from the other wireless power transmission device; calculating a coupling factor with the other wireless power transmission device based at least in part on the received identification information and the received voltage information; calculating a power transfer level based on the calculated coupling factor; as well as A power contract is negotiated with the other wireless power transfer device based at least in part on the calculated power transfer level. 18 . The wireless power transmission device according to claim 17 , wherein the identification information specifically identifies the other wireless power transmission device.

19. The wireless power transmission device of claim 17, wherein the identification information identifies the other wireless power transmission device as a member of a class of wireless power transmission devices.

20. The wireless power transmission device of claim 17, wherein the coupling factor is calculated according to the following equation: Where k is the coupling factor, Vrect is the rectifier voltage of the wireless power receiver, Vinv is the DC input voltage of the inverter of the wireless power transmitter, VCTXpp is the peak voltage across the transmitter tuning capacitor, and C0 and C1 are fitting coefficients.

21. The wireless power transmission device according to claim 20, in: The wireless power transmission device is the wireless power receiver, and the other wireless power transmission device is the wireless power transmitter; and Vinv and VCTXpp are at least a portion of the received voltage information.

22. The wireless power transmission device of claim 20, wherein the power transmission level is calculated according to the following equation: P target =k 2 ·C pwr Where Ptarget is the power that can be delivered to the wireless power receiver, k is the coupling factor, and Cpwr is a constant that is available to the controller and communication module and is a transmitter / receiver combination selected based on the received identification information.

23. The wireless power transmission device of claim 22, wherein Cpwr is stored in a memory of the controller and retrieved based at least in part on the received identification information.

24. The wireless power transmission device of claim 22, wherein Cpwr is included in the received identification information.

25. The wireless power transmission device of claim 22, wherein Cpwr is calculated according to the following formula: where Prect_max is the maximum total power level required by the receiver, RXLoss is the power loss in the receiver, and kmin is the minimum coupling coefficient corresponding to the maximum acceptable displacement between transmitter and receiver.

26. The wireless power transmission device of claim 17, wherein the power transmission level is calculated according to the following equation: P target =k 2 ·C pwr Where Ptarget is the power that can be delivered to the wireless power receiver, k is the coupling factor, and Cpwr is a constant that is available to the controller and communication module and is a transmitter / receiver combination selected based on the received identification information.

27. The wireless power transmission device of claim 26, wherein Cpwr is stored in a memory of the controller and retrieved based at least in part on the received identification information.

28. The wireless power transmission device of claim 26, wherein Cpwr is included in the received identification information.

29. The wireless power transmission device of claim 26, wherein Cpwr is calculated according to the following formula: where Prect_max is the maximum total power level required by the receiver, RXLoss is the power loss in the receiver, and kmin is the minimum coupling coefficient corresponding to the maximum acceptable displacement between transmitter and receiver.

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