Wireless power transfer control loop with variable gain coefficient

Abstract

To provide a wireless power system for charging electronic devices.SOLUTION: A wireless charging system 8 includes a wireless power receiving device 24 which receives wireless power signals from a wireless power transmission device 12, and the wireless power receiving device transmits power feedback information to the wireless power transmission device. The wireless power transmission device updates operational characteristics of an inverter using a variable gain coefficient based on the received power feedback information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application claims priority to U.S. Patent Application No. 19 / 035,599, filed January 23, 2025, U.S. Provisional Patent Application No. 63 / 709,899, filed October 21, 2024, and U.S. Provisional Patent Application No. 63 / 571,480, filed March 29, 2024, which applications are incorporated herein by reference in their entireties. FIELD OF THE INVENTION This application relates generally to power systems, and more particularly to wireless power systems for charging electronic devices. [Background technology]

[0002] In a wireless charging system, a wireless power transmitting device wirelessly supplies power to a wireless power receiving device, which uses the wireless power to charge a battery and / or power components, and the wireless power receiving device may provide feedback to the wireless power transmitting device to control wireless power transfer operation. Summary of the Invention

[0003] The electronic device can be configured to transfer wireless power with an additional electronic device, and can include a wireless power transmission coil, an inverter configured to provide an AC drive signal to the wireless power transmission coil, and a control circuit configured to receive information from the additional electronic device, including power feedback information, and adjust at least one operating characteristic of the inverter using a variable gain factor and the power feedback information.

[0004] The electronic device may be configured to receive wireless power from an additional electronic device. The electronic device may include a wireless power transmission coil, a rectifier connected to the wireless power transmission coil having a target output voltage and an actual output voltage, and a control circuit configured to determine a value proportional to a difference between the target output voltage and the actual voltage divided by the actual output voltage, send the value to the additional electronic device, and send a constant between 0 and 1 to the additional electronic device. The constant may affect the magnitude of a change in wireless power output by the additional electronic device depending on the sent value. [Brief explanation of the drawings]

[0005] [Figure 1] 1 is a schematic diagram of an exemplary wireless power system, according to some embodiments.

[0006] [Figure 2] FIG. 1 is a circuit diagram of a wireless power transmitting and receiving circuit, according to some embodiments.

[0007] [Figure 3] FIG. 1 is a circuit diagram of an exemplary wireless power transmission circuit having an inverter according to some embodiments.

[0008] [Figure 4A] 5A-5C are example timing diagrams of inverter control signals when the inverter has different phases of operation, according to some embodiments. [Figure 4B] 5A-5C are example timing diagrams of inverter control signals when the inverter has different phases of operation, according to some embodiments.

[0009] [Figure 5] 1 is a flowchart of an exemplary method of operating a wireless power transmitting device during a power control operation, according to some embodiments.

[0010] [Figure 6A]10 is an example equation for a power feedback value with a target rectifier output voltage in the denominator, according to some embodiments.

[0011] [Figure 6B] 10 is an example equation for a power feedback value with actual rectifier output voltage in the denominator, according to some embodiments.

[0012] [Figure 7] 1 is an exemplary equation for a variable gain factor used to determine a voltage step, according to some embodiments.

[0013] [Figure 8] 10 is an exemplary equation for a variable gain factor used to determine a phase step, according to some embodiments.

[0014] [Figure 9A] 10 is an exemplary graph of inverter phase as a function of loop iteration during power ramp-up according to some embodiments.

[0015] [Figure 9B] 10 is an exemplary graph of inverter voltage as a function of loop iteration during power ramp-up according to some embodiments.

[0016] [Figure 9C] 10 is an exemplary graph of actual rectifier output voltage as a function of loop iteration during power ramp-up according to some embodiments.

[0017] [Figure 10] 1 is a state diagram illustrating exemplary modes of operation of a wireless power transmission device according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0018] An exemplary wireless power system (sometimes referred to as a wireless charging system) is shown in Figure 1. As shown in Figure 1, the wireless power system 8 may include one or more wireless power transmitting devices, such as a wireless power transmitting device 12, and one or more wireless power receiving devices, such as a wireless power receiving device 24. The wireless power system 8 is sometimes referred to herein as a wireless power transfer (WPT) system 8 or a wireless power system 8. The wireless power transmitting device 12 is sometimes referred to herein as a power transmitter (PTX) device 12 or simply PTX 12. The wireless power receiving device 24 is sometimes referred to herein as a power receiver (PRX) device 24 or simply PRX 24.

[0019] The PTX device 12 includes control circuitry 16. The control circuitry 16 is mounted within a housing 30. The PRX device 24 includes control circuitry 38 mounted within a corresponding housing 52 for the PRX device 24. The exemplary control circuitry 16 and control circuitry 38 are used in controlling the operation of the WPT system 8. This control circuitry may include processing circuitry including one or more processors, such as a microprocessor, a power management unit, a baseband processor, a digital signal processor, a microcontroller, a graphics processing unit (GPU), a central processing unit (CPU), an application processor (AP), an application specific integrated circuit having processing circuitry, and / or other processing circuitry. The processing circuitry performs the desired control and communication functions within the PTX device 12 and the PRX device 24. For example, the processing circuitry may be used to control power to one or more coils, determine and / or set transmission power levels, generate and / or process sensor data (e.g., to detect foreign objects and / or external electromagnetic signals or fields), process user input, handle negotiation between the PTX device 12 and the PRX device 24, send and receive in-band and out-of-band data, take measurements, and / or control the operation of the WPT system 8.

[0020] Control circuitry within WPT system 8 (e.g., control circuitry 16 and / or 38) may be configured to perform operations within WPT system 8 using hardware (e.g., dedicated hardware or circuitry), firmware, and / or software. Software code for performing operations within WPT system 8 is stored on a non-transitory computer-readable storage medium (e.g., a tangible computer-readable storage medium) within the control circuitry of WPT system 8. The software code may also 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 non-volatile random-access memory (NVRAM), one or more hard drives (e.g., magnetic drives or solid-state drives), one or more removable flash drives, or other removable media. Software stored on the non-transitory computer-readable storage medium may be executed on processing circuitry within control circuitry 16 and / or 38.

[0021] The PTX device 12 may be a standalone power adapter (e.g., a wireless charging mat or charging pack including power adapter circuitry), a wireless charging mat or pack connected by a cable to a power adapter or other device, an electronic device (e.g., a laptop computer, a desktop computer, a computer monitor with an embedded computer, a tablet computer, a mobile phone, a media player, or other handheld or portable electronic device, a small device such as a wristwatch device, a pendant device, a headphone or earphone device, a device incorporated into eyeglasses, goggles, or other equipment worn on the user's head, or other wearable or miniature device, a television, a computer display without an embedded computer, a gaming device, a navigation device, a wireless Internet-connected voice-controlled speaker, a home entertainment device, a remote control device, a gaming controller, a peripheral user input device, a wireless base station or access point, a device that implements the functions of two or more of these devices, or other electronic device), a device incorporated into furniture, a vehicle, or other system, a removable battery case, or other wireless power transmission device.

[0022] The PRX device 24 may be an electronic device such as a laptop computer, desktop computer, computer monitor including an embedded computer, tablet computer, cellular telephone, media player, or other handheld or portable electronic device, a small device such as a wristwatch device, pendant device, headphone or earphone device, eyeglasses, a device embedded in goggles or other equipment worn on a user's head, or other wearable or miniature device, a wireless tracking tag, a television, a computer display without an embedded computer, a gaming device, a navigation device, a voice-controlled wireless speaker connected to the Internet, a home entertainment device, a remote control device, a gaming controller, a peripheral user input device, a wireless base station or access point, a device implementing the functionality of two or more of these devices, or other electronic equipment.

[0023] The PTX device 12 may be connected to a wall outlet (e.g., an AC power source), may be coupled to the wall outlet via an external power adapter, may have a battery for providing power, and / or may have another power source. In implementations in which the PTX device 12 is coupled to a wall outlet via an external power adapter, the adapter may have an AC-DC power converter that converts alternating current (AC) power from the wall outlet or other power source to direct current (DC) power. If necessary, the PTX device 12 may include a DC-DC power converter for converting DC power between different DC voltages. Additionally or alternatively, the PTX device 12 may include an AC-DC power converter that generates DC power from AC power provided by the wall outlet (e.g., in implementations in which the PTX device 12 is connected to a wall outlet without an external power adapter). The DC power can be used to power the control circuitry 16. During operation, a controller within the control circuitry 16 transmits wireless power to the power receiving circuitry 46 of the PRX device 24 using the power transmitting circuitry 22.

[0024] The power transmission circuitry 22 may include switching circuits (e.g., inverter circuits 26 formed from transistors) that are turned on and off based on control signals provided by the control circuitry 16 to generate AC current signals through one or more wireless power transmission coils, such as the wireless power transmission coil 32. These coil drive signals cause the coil(s) 32 to transmit wireless power. In implementations in which the coil(s) 32 include multiple coils, the coils may be disposed on a ferromagnetic structure, arranged in a planar coil array, or arranged to form a cluster of coils (e.g., two or more coils, 5-10 coils, at least 10 coils, 10-30 coils, less than 35 coils, less than 25 coils, or any other suitable number of coils). In some implementations, the PTX device 12 includes only a single coil 32.

[0025] When AC current flows through one or more coils 32, 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 PRX device 24. In other words, one or more of the coils 32 is inductively coupled to one or more of the coils 48. The PRX device 24 may have a single coil 48, at least two coils 48, at least three coils 48, at least four coils 48, or another suitable number of coils 48. When the AC electromagnetic field is received by the coil(s) 48, a corresponding alternating current is induced in the coil(s) 48. The AC signal used in transmitting wireless power may have any desired frequency (e.g., 100-400 kHz, 1-100 MHz, 1.7 MHz-1.8 MHz, less than 2 MHz, 100 kHz-2 MHz, 13 MHz-14 MHz, etc.). A rectifier circuit such as rectifier circuit 50, which includes rectifying components such as synchronous rectifier transistors arranged in a bridge network, converts the received AC signal (the received alternating current signal associated with the wireless power signal 44) into a DC voltage signal for powering the PRX device 24 from one or more coils 48. The wireless power signal 44 may be referred to herein as wireless power 44 or a wireless charging signal 44. The coil 32 may be referred to herein as a wireless power transmission coil 32, a wireless charging coil 32, or a wireless power transmitting coil 32. The coil 48 may be referred to herein as a wireless power transmission coil 48, a wireless charging coil 48, or a wireless power receiving coil 48.

[0026] The DC voltage produced by rectifier circuit 50 (sometimes referred to as rectifier output voltage Vrect) may be used to charge a battery, such as battery 34, or to power other components within PRX device 24, such as control circuit 38 and input / output (I / O) device 54. PTX device 12 may also include input / output devices, such as input / output device 28. I / O device 54 and / or I / O device 28 may include input devices for collecting user input and / or making environmental measurements, and may include output devices for providing output to a user.

[0027] By way of example, input / output device 28 and / or input / output device 54 may include a display (screen) for generating visual output, a speaker for presenting output as an audio signal, light-emitting diode status indicator lights and other light-emitting components for emitting light that provides status and / or other information to a user, tactile devices for generating vibrations and other tactile output, and / or other output devices. Input / output device 28 and / or input / output device 54 may also include sensors for gathering input from a user and / or for taking measurements around WPT system 8.

[0028] 1 example of a PRX device 24 including a battery 34 is illustrative. More generally, an electronic device may include a power storage device 34. The power storage device 34 may be a battery or, for example, a supercapacitor that stores an electrical charge.

[0029] The PTX device 12 and the PRX device 24 can communicate wirelessly using in-band or out-of-band communication. Implementations using in-band communication can utilize, for example, frequency shift keying (FSK) and / or amplitude shift keying (ASK) techniques to communicate in-band data between the PTX device 12 and the PRX device 24. Wireless power and in-band data transmissions can be carried simultaneously using coils 32 and 48. When the PTX 12 transmits in-band data to the PRX 24, the wireless transceiver (TX / RX) circuit 20 can modulate the wireless charging signal 44 to provide FSK or ASK communication, and the wireless transceiver circuit 40 can demodulate the wireless charging signal 44 to obtain the communicated data. When the PRX 24 transmits in-band data to the PTX 12, the wireless transceiver (TX / RX) circuit 40 can modulate the wireless charging signal 44 to provide FSK or ASK communication, and the wireless transceiver circuit 20 can demodulate the wireless charging signal 44 to obtain the communicated data.

[0030] Implementations using out-of-band communication may utilize, for example, a hardware antenna structure and a communication protocol such as Bluetooth or NFC to communicate out-of-band data between the PTX device 12 and the PRX device 24. Power may be transferred wirelessly between the coils 32 and 48 concurrently with the out-of-band data transmission. The wireless transceiver circuit 20 may wirelessly transmit and / or receive out-of-band signals to and / or from the PRX device 24 using an antenna such as antenna 56. The wireless transceiver circuit 40 may wirelessly transmit and / or receive out-of-band signals to and / or from the PTX device 12 using an antenna such as antenna 58.

[0031] The control circuitry 16 within the PTX device 12 includes measurement circuitry 18 that can be used to perform measurements of one or more characteristics external to the PTX device 12. For example, the measurement circuitry 18 may detect external objects on or adjacent to the charging surface of the housing of the PTX device 12. Although shown in FIG. 1 as separate from the transmission circuitry 22 for clarity, the measurement circuitry 18 may form part of the transmission circuitry 22 if desired.

[0032] The measurement circuitry 18 may detect foreign objects such as coils, paper clips, and other metal objects, may detect the presence of the PRX device 24 (e.g., the circuitry 18 may detect the presence of one or more coils 48 and / or magnetic core material associated with the coils 48), and / or may detect the presence of other power transmitting devices in the vicinity of the PTX device 12 and / or WPT system 8. The measurement circuitry 18 may also be used to make sensor measurements using capacitive sensors, to make temperature measurements, and / or otherwise be used in collecting information indicative of whether a foreign object, power transmitting device, power receiving device, or other external object (e.g., the PRX device 24) is present on or adjacent to the coil(s) 32 of the PTX device 12. Optionally, the PRX device 24 may include a measurement circuitry 42. The measurement circuitry 42 may perform one or more of the measurements performed by the measurement circuitry 18 (e.g., for or using the coil(s) 48 on the PRX device 24).

[0033] Each of housing 30 and housing 52 may be formed from plastic, metal, fiber composite materials such as carbon fiber materials, wood and other natural materials, glass, other materials, and / or combinations of two or more of these materials.

[0034] 1, in which PTX 12 transmits wireless power and PRX 24 receives wireless power, is merely illustrative. PTX 12 can optionally receive wireless power signals using coil(s) 32, and PRX 24 can optionally transmit wireless power signals using coil(s) 48. When a device is capable of both transmitting and receiving wireless power signals, the device may include both an inverter and a rectifier.

[0035] 2 is a circuit diagram of an exemplary wireless charging circuit for system 8. As shown in FIG. 2, circuit 22 can include one or more inverter circuits, such as inverters 26, or other drive circuits, that generate a wireless power signal that is transmitted through an output circuit that includes one or more coils 32 and a capacitor, such as capacitor 70. In some embodiments, device 12 can include multiple individually controlled inverters 26, each providing a drive signal to a separate coil 32. In other embodiments, inverter 26 is shared among multiple coils 32 using switching circuitry.

[0036] During operation, control signals for the inverter(s) 26 are provided by the control circuitry 16 at one or more control inputs 74. While a single inverter 26 and a single coil 32 are shown in the embodiment of FIG. 2, multiple inverters 26 and multiple coils 32 may be used if desired. In a multiple coil configuration, switching circuitry (e.g., a multiplexer circuit) may be used to couple a single inverter 26 to multiple coils 32 and / or to couple each coil 32 to a separate inverter 26. During wireless power transmission operation, transistors within one or more selected inverters 26 are driven by AC control signals from the control circuitry 16. The relative phase between the inverters may be dynamically adjusted (e.g., a pair of inverters 26 may generate in-phase or out-of-phase output signals).

[0037] Applying a drive signal using inverter(s) 26 (e.g., a transistor or other switch in circuit 22) causes an output circuit formed from selected coils 32 and capacitors 70 to generate an alternating electromagnetic field (signal 44) that is received by wireless power receiving circuit 46 using a wireless power receiving circuit formed from one or more coils 48 and one or more capacitors 72 in device 24.

[0038] The rectifier circuit 50 is coupled to the one or more coils 48 and converts the received power from AC to DC and provides a corresponding DC output voltage Vrect across the rectifier output terminals 76 for powering load circuits within the device 24 (e.g., for charging the battery 34, for powering the display and / or other input / output devices 54, and / or for powering other components).

[0039] 2 shows how measurement circuitry 18 in PTX 12 can include one or more voltage sensors, such as voltage sensor 18A, and one or more current sensors, such as current sensor 18B. Additionally, measurement circuitry 42 in PRX 24 can include one or more voltage sensors, such as voltage sensor 42A, and one or more current sensors, such as current sensor 42B. The voltage and current sensors in system 8 can be used to determine power levels within the system.

[0040] 2 (on the DC side of inverter 26 and rectifier 50, respectively) are merely exemplary. In general, voltage and current sensors may be placed in any desired position within transmitting circuit 22 and receiving circuit 46 (e.g., on the AC side of inverter 26 and rectifier 50, as desired).

[0041] 3 is a circuit diagram illustrating the configuration of inverter 26 in power transmission circuit 22. As shown in FIG. 3, inverter 26 may be a full-bridge inverter including four switches arranged in a bridge configuration. Switches T1 and T4 provide an adjustable voltage V IN In parallel with switches T1 and T4, switches T3 and T2 are connected in series between a control terminal providing an adjustable voltage V INand ground. Inductor 32 and capacitor 70 are connected between a first node between T1 and T4 and a second node between T2 and T3. The four switches (T1, T2, T3, and T4) may be power metal-oxide semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), or other desired switching components. Figure 3 shows an example in which switches T1, T2, T3, and T4 (sometimes referred to as transistors T1, T2, T3, and T4) are power MOSFETs.

[0042] During operation of the inverter 26, transistors T1, T2, T3, and T4 may be switched on and off in pairs. During one half-cycle of the output waveform, one pair of transistors (e.g., transistors T1 and T2) is conducting (turned on), while the other pair is turned off. Then, during the next half-cycle, the conducting transistors (T1 and T2) are switched off, and the previously turned-off transistors (T3 and T4) are turned on. This process is repeated to generate the desired AC output waveform as input to the wireless power transmission coil 32.

[0043] 3 shows an example in which transistors T1 and T2 receive a common control signal SW1 and transistors T3 and T4 receive a common control signal SW2. The control signals SW1 and SW2 can be alternately switched between a first state and a second state (e.g., a high state and a low state) to operate inverter 26.

[0044] There are several operating characteristics of the inverter 26 that can be adjusted during operation of the PTX 12. These operating characteristics are determined by the inverter voltage V IN , the operating phase θ, the duty cycle, and the frequency of the output AC current signal produced by inverter 26.

[0045] As shown in FIG. 3, the inverter 26 generates a variable DC voltage V IN It can be connected to V INThe magnitude of V can be adjusted to control the amount of wireless power transmitted by the power transmitting circuit 22. IN Increasing V increases the magnitude of the wireless power transmitted by the power transmitting circuit 22, IN Decreasing τ decreases the amount of wireless power transmitted by the power transmitting circuit 22.

[0046] The inverter 26 may also have an associated operating phase. The operating phase θ (sometimes referred to as the inverter phase θ) may refer to the offset between the control signals SW1 and SW2. FIG. 4A shows a timing diagram of SW1 and SW2 when the inverter phase is equal to 0 degrees. FIG. 4B shows a timing diagram of SW1 and SW2 when the inverter phase is equal to 180 degrees. Using the conventions of FIGS. 4A and 4B, the 0 (zero) degree operating phase is defined as the state where SW2 is the inverse of SW1, and the 0 degree operating phase is defined as the state where SW2 is the same as SW1. In the 0 degree operating phase, when SW1 changes from high to low, SW2 changes from low to high, and when SW1 changes from low to high, SW2 changes from high to low. In other words, when the operating phase is 0 degrees, the waveforms of SW1 and SW2 are offset by a half period. In the 180-degree operating phase, when SW1 changes from low to high, SW2 changes from low to high, and when SW1 changes from high to low, SW2 changes from high to low. In other words, when the operating phase is 180 degrees, the waveforms of SW1 and SW2 are synchronized.

[0047] 4A and 4B, the effective output voltage of the inverter is maximum when the phase is equal to 0 degrees (as shown in FIG. 4A) and minimum when the phase is equal to 180 degrees (as shown in FIG. 4B). Therefore, adjusting the phase of inverter 26 can adjust the magnitude of the wireless power transmitted by transmitting circuit 22. Between 0 degrees and 180 degrees, increasing the phase causes a decrease in the magnitude of the wireless power transmitted by transmitting circuit 22, and decreasing the phase causes an increase in the magnitude of the wireless power transmitted by transmitting circuit 22.

[0048] In some configurations, the inverter 26 may operate at a fixed duty cycle (e.g., a fixed 50% duty cycle). A fixed duty cycle may refer to the duty cycle of the control signals SW1 and SW2. 4A and 4B show an example in which SW1 and SW2 have a fixed 50% duty cycle. In other configurations, the inverter 26 may operate at an adjustable duty cycle, and the duty cycle may be adjusted to increase or decrease the amount of wireless power transmitted by the power transmission circuit 22.

[0049] The inverter 26 may be capable of operating at different wireless power transmission signal frequencies. The PTX device 12 may, as an example, use different wireless power transmission signal frequencies for different PRX devices. In some configurations, the wireless power transmission signal frequency may not be adjusted to adjust the magnitude of the wireless power transmitted by the transmit circuit 22. In these configurations, the wireless power transmission signal frequency is fixed during the power transmission phase, and the inverter voltage and phase are adjusted to adjust the magnitude of the wireless power transmitted by the transmit circuit 22. In other configurations, the wireless power transmission signal frequency may be adjusted to adjust the magnitude of the wireless power transmitted by the transmit circuit 22.

[0050] To control the amount of power transferred from the PTX device 12 to the PRX device 24, a power supply control system may be used in which the PRX device 24 reports power feedback information to the PTX device 12. Based on the power feedback information, the PTX device 12 may adjust the operating characteristics of the inverter 26 (e.g., inverter voltage and / or phase) to adjust the amount of power being transferred from the PTX device 12 to the PRX device 24. The PRX device 24 may then report power feedback information back to the PTX device 12, and the cycle repeats. Examples of power feedback information include the Control Error Packet (CEP) and Extended Control Error Packet (XCE) in the Qi standard as defined by the Wireless Power Consortium organization.

[0051] 5 is a flowchart illustrating an exemplary method performed by the PTX device 12 to adjust the magnitude of power transmission based on received power feedback information. Initially, during operation of block 102, the PTX device 12 may receive a packet from the PRX 24. The PTX device 12 may receive the packet from the PRX 24 using in-band communication (e.g., using FSK or ASK). In some use cases, this packet is a CEP or XCE packet that includes power feedback information.

[0052] As previously discussed in connection with FIG. 2, the PRX device 24 regulates the rectifier output voltage V RECT The rectifier output voltage is the actual rectifier output voltage V RECT The PRX device 24 also determines the target rectifier output voltage V RECT_TARGET The purpose of the feedback loop in FIG. 5 is to increase or decrease the power supplied by the PTX 12 to the PRX 24 so that the actual rectifier output voltage reaches the target rectifier output voltage. It is also beneficial to have this power control occur quickly while maintaining stable operation. During wireless power transmission, the PRX 24 may compare the actual rectifier output voltage with the target rectifier output voltage. When there is a difference between the actual rectifier output voltage and the target rectifier output voltage, the PRX 24 may use the power feedback information packet to transmit a value proportional to the difference between the actual rectifier output voltage and the target rectifier output voltage. In the case of the XCE packet described above, this value is provided in the XCE Value (XCEV) field of the packet.

[0053] The actual rectifier output voltage can be determined using a voltage sensor, such as voltage sensor 42A in FIG. 2. The voltage sensor may include a calibrated ADC that samples the rectifier output voltage every 10 milliseconds (or at another desired sampling frequency). V RECT The magnitude of may be determined by averaging the output from the voltage sensor over a number of recent samples.

[0054] XCEV is the difference between the actual rectifier output voltage and the target rectifier output voltage (e.g., V RECT_TARGET -V RECT 6A and 6B are exemplary equations that may be used to determine the magnitude of the extended control error value (XCEV). In both equations of FIG. 6A and FIG. 6B, XCEV is the extended control error value included in the packet received during operation of block 102, and V RECT is the actual rectifier output voltage, and V RECT_TARGET is the target rectifier output voltage (as previously described). In FIG. 6A, the error term (V RECT_TARGET -V RECT ) is V RECT - _TARGET In Figure 6B, the error term (V RECT_TARGET -V RECT ) is V RECT- 6B for XCEV can be advantageous when the PTX 12 operates in a gain linearization mode, as will be explained in more detail later.

[0055] 6A and 6B may optionally be subjected to a floor function that outputs the largest integer that is less than or equal to the result of the equation. If a floor function is used, an additional term of "+1 / 2" may be included in the XCEV equation.

[0056] After receiving a packet from PRX 24 during operation of block 102, PTX 12 may, during operation of block 104, adjust at least one operating characteristic of inverter 26 based on the power feedback information from the packet from block 102. In particular, PTX 12 may obtain the XCEV from the packet and use the XCEV to adjust (e.g., increase or decrease) either the inverter voltage or the inverter phase.

[0057] There are many possible control strategies that can be applied by PTX 12 to adjust the operating characteristics of inverter 26 based on the received XCEV. Figure 5 illustrates one example of a control strategy in operation of blocks 106, 108, 110, and 112.

[0058] During the operation of block 106, the XCEV may be capped to ensure that the XCEV is less than or equal to the maximum allowed XCEV (XCEV_MAX) and greater than or equal to the minimum allowed XCEV (XCEV_MIN). If the received XCEV is greater than the maximum allowed XCEV, the XCEV may be set equal to the maximum allowed XCEV. If the received XCEV is less than the minimum allowed XCEV, the XCEV may be set equal to the minimum allowed XCEV. Written as a formula, XCEV_capped = max(min(XCEV, XCEV_MAX), XCEV_MIN).

[0059] After XCEV is capped during operation of block 106, a voltage step can be determined during operation of block 108, and a phase step can be determined during operation of block 110. The voltage step in block 108 can be an adjustment to the current inverter voltage determined by multiplying XCEV by a first gain factor (e.g., Voltage_step=XCEV_capped * Voltage_gain, where Voltage_gain is a first gain coefficient. The phase step in block 110 may be an adjustment to the current inverter phase determined by multiplying XCEV by a second gain coefficient (e.g., Phase_step=XCEV_capped * Phase_gain, where Phase_gain is the second gain factor).

[0060] Then, during operation of block 112, control circuit 16 can adjust the inverter voltage using the voltage step from block 108 and / or the inverter phase using the phase step from block 110. In some control strategies, both inverter phase and voltage can be updated during operation of block 112. Alternatively, in the exemplary control strategy described here by way of example, only one of phase and voltage can be adjusted at a time during operation of block 112. There are several ways to prioritize adjustments to inverter phase compared to adjustments to inverter voltage. Inverter phase may have a minimum value (PHASE_MIN) and a maximum value (PHASE_MAX), and inverter voltage may have a minimum value (VIN_MIN) and a maximum value (VIN_MAX). In one exemplary control strategy, priority is placed on having the inverter phase (with the associated maximum possible power delivery) being the smallest over inverter voltage (with the associated maximum possible power delivery).

[0061] V RECT V RECT_TARGET Consider a scenario where XCEV is less than 0. In this scenario, XCEV is greater than 0, indicating that the PRX 24 is requesting an increase in power from the PTX 12. When XCEV is greater than 0 and the inverter phase is not equal to PHASE_MIN, the inverter phase may be adjusted according to the equation θ=θ+Phase_step (the inverter voltage is not adjusted). When XCEV is greater than 0 and the inverter phase is equal to PHASE_MIN, the inverter voltage is adjusted according to the equation V IN =V IN +Voltage_step (inverter phase is not adjusted).

[0062] V RECT V RECT_TARGET Consider a scenario where XCEV is greater than VIN_MIN. In this scenario, XCEV is less than 0, indicating that the PRX 24 is requesting a decrease in power from the PTX 12. When XCEV is less than 0 and the inverter voltage is not equal to VIN_MIN, the inverter voltage is reduced by the equation V IN =V IN+Voltage_step (the inverter phase is not adjusted). When XCEV is less than 0 and the inverter voltage is equal to VIN_MIN, the inverter phase can be adjusted according to the equation θ=θ+Phase_step (the inverter voltage is not adjusted).

[0063] When the calculated inverter phase is greater than PHASE_MAX, the inverter phase may be set equal to PHASE_MAX. When the calculated inverter phase is less than PHASE_MIN, the inverter phase may be set equal to PHASE_MIN. In formula form, θ=max(min(θ+Phase_step, PHASE_MAX), PHASE_MIN).

[0064] When the calculated inverter voltage is greater than VIN_MAX, the inverter voltage can be set equal to VIN_MAX. When the calculated inverter voltage is less than VIN_MIN, the inverter phase can be set equal to VIN_MIN. Written as a formula, VIN = max(min(VIN + Voltage_step, VIN_MAX), VIN_MIN).

[0065] As illustrative examples, XCEV_MAX may be equal to 64, XCEV_MIN may be equal to -64, PHASE_MIN may be equal to 0 degrees, PHASE_MAX may be equal to 50 degrees, VIN_MIN may be 6.5V, 10V, 16V, between 6V and 18V, less than 17V, between 8V and 18V, etc., and VIN_MAX may be 18V, 20V, between 17V and 22V, less than 21V, etc.

[0066] Thus, during operation of FIG. 5, the magnitude of the adjustment to the inverter phase or inverter voltage depends on the magnitude of XCEV and the magnitude of the corresponding gain factor.

[0067] In a first mode of operation, sometimes referred to as a constant gain mode, the gain factor may be a constant. As an example, Phase_gain may be calculated using the above formula: Phase_step=XCEV_capped* Phase_gain may be equal to -0.16 degrees, and Voltage_gain may be equal to Voltage_step=XCEV_capped using the formula above. * It may be equal to 0.16mV in Voltage_gain.

[0068] Using constant values ​​for the gain coefficients Phase_gain and Voltage_gain may be a satisfactory technique for regulating phase and voltage during power transfer control. However, the magnitude of the constants may need to be sufficiently conservative to ensure stability over a wide range of operating conditions. Having conservative, constant gain coefficients may cause the control loop to run slower than desired in certain operating conditions. In other words, the magnitude of the gain coefficients controls the rate of ramp-up (or ramp-down) during power supply regulation. A constant gain coefficient may result in a slower ramp-up (or ramp-down) than desired during some operating conditions.

[0069] Some of the causes of slow ramp-up (or ramp-down) when a constant gain factor is used are: a reduction in the circuit gain during the phase ramp (causing the effective drive to vary over time during the phase ramp); V IN From V RECT These are large variations in circuit gain to (which may be caused by different positional offsets between the PTX device 12 and the PRX device 24 and / or varying load conditions on the PRX device 24), and large variations in the designs for the PTX device 12 and the PRX 24. The constant gain factor must be selected to accommodate the factors listed above, which cause an overly conservative ramp-up (or ramp-down) in many operating conditions.

[0070] To improve the speed of ramp-up (or ramp-down) over a wide range of operating conditions, the PTX 12 may be operable in a second mode (sometimes referred to as a gain linearization mode) in which the gain factor is variable and compensates for the circuit gain. The use of a variable gain factor (sometimes referred to as a dynamic gain factor) in the second mode reduces V compared to the first mode when a constant gain factor is used. RECT V RECT_TARGET This may improve the speed of matching.

[0071] 7 and 8 show the equations for the variable gain coefficients. Figure 7 shows the equation for the variable gain coefficient used to determine the voltage step during operation of block 108. In the equation in Figure 7, VIN_gain is the variable gain coefficient, V IN is the inverter voltage, θ is the inverter phase, g target is a value between 0 and 1. g target The magnitude of g may be selected by the PTX 12 or PRX 24 to set the power convergence speed and stability. target causes a more aggressive (e.g., faster) ramp-up (or ramp-down) in the power supply, resulting in a lower magnitude of g target causes a less aggressive (e.g., slower) ramp-up (or ramp-down) in the power supply. In general, g is used (to maximize convergence speed) while ensuring stability within the system. target It may be desirable to choose the magnitude of g as high as possible. target Choosing the magnitude of can help stabilize the system.

[0072] In some cases, g target The magnitude of g can be fixed. For example, the PTX 12 has a constant g regardless of operating conditions. targetIn another possible example, the PTX 12 may use a magnitude of 0.5 for g based on one or more factors such as the device type of the PRX 24 (e.g., whether the PRX is a cell phone, a watch, or other type of device), the state of charge of the battery within the PRX 24 (as reported by the PRX 24 to the PTX 12), etc. target In another possible example, the PTX 24 may change the g based on one or more factors such as the device type of the PTX 12 (e.g., whether the PTX is a standalone power adapter, whether it is a wireless charging mat or pack connected by a cable to a power adapter or other device, whether it is a mobile phone, or other type of device), the charge state of the battery 34 within the PRX 24, etc. target can be changed.

[0073] In another possible configuration, the PRX 24 may be configured to operate in a V RECT Based on the most recent changes in g target After each loop iteration (e.g., each repeat cycle of the operations of FIG. 5), the PRX 24 may change V from before to after the PTX adjusts its operating characteristics, per the operations of block 104 of FIG. RECT For example, V RECT_CHANGE ) can be calculated. For example, V RECT_CHANGE =V RECT '-V RECT where V RECT ' is the rectifier voltage from before the most recent loop iteration (e.g., before the operating characteristics were updated in block 104), and V RECT is the rectifier voltage since the most recent loop iteration (e.g., since the operating characteristics were updated in block 104). RECT_CHANGE After calculating, PRX 24 is observed can be calculated, where g observed =V RECT_CHANGE / (V RECT_TARGET -V RECT ) g observed After calculating, PRX 24 calculates g observedcan be compared to a constant G (or more generally, a threshold value). The constant G may be 1 or less (e.g., 0.8 to 1.0, 0.9 to 1.0, etc.). observed When is greater than G, PRX 24 is g target g observed When is less than G, PRX 24 is g target can be reduced.

[0074] Note that the equations in Figures 6A, 6B, and 7 include the constant 128. The magnitude of this constant may be related to the number of bits in the XCEV. In this example, the XCEV has 8 bits, and 128 is used to scale to the 8-bit limit. If the XCEV has a different range (e.g., a different number of bits), a constant other than 128 may be used in the equations in Figures 6A, 6B, and 7. In general, the value of the constant may be proportional to the bit length of the associated field in the power feedback data packet.

[0075] Figure 8 is an equation for the variable gain coefficient used to determine the phase step during operation of block 110. In the equation of Figure 8, Phase_gain is the variable gain coefficient used to determine the phase step, VIN_gain is the variable gain coefficient calculated using the equation of Figure 7, VIN_MIN is the minimum inverter voltage, and θ is the inverter phase. Note that the equation of Figure 8 can optionally include a small constant (e.g., 0.01) in the denominator to avoid divide-by-zero errors.

[0076] The formulas in Figures 7 and 8 are merely examples. In general, VIN_gain is

number

number

[0077] Note that using the equation of Figure 6B for XCEV may simplify the gain linearization operation of the PTX 12. When the equation of Figure 6B is used for XCEV, the equation for the variable gain coefficient for determining the voltage step is simplified.

[0078] The operation of FIG. 5 is illustrated by feedback loop 114 in FIG. RECT V RECT_TARGET can be repeated repeatedly until it matches.

[0079] 9A-9C are graphs illustrating different parameters during power transfer operation between the PTX 12 and the PRX 24. FIG. 9A illustrates inverter phase over multiple loop iterations (e.g., multiple inverter adjustments as illustrated by the feedback loop in FIG. 5), FIG. 9B illustrates inverter voltage over multiple loop iterations, and FIG. 9C illustrates actual rectifier output voltage over multiple loop iterations. FIG. 9A illustrates a first profile 122 for inverter phase when the PTX 12 operates in a constant gain mode using a constant gain coefficient, and a second profile 124 for inverter phase when the PTX 12 operates in a gain linearization mode using a variable gain coefficient. FIG. 9B illustrates a first profile 126 of inverter voltage when the PTX 12 operates in a constant gain mode using a constant gain coefficient, and a second profile 128 of inverter voltage when the PTX 12 operates in a gain linearization mode using a variable gain coefficient. FIG. 9C shows a first profile 130 of the actual rectifier output voltage when the PTX 12 operates in a constant gain mode using a constant gain coefficient, and a second profile 132 of the actual rectifier output voltage when the PTX 12 operates in a gain linearization mode using a variable gain coefficient.

[0080] 9A-9C, at time 0, the actual rectifier output voltage may be less than the target rectifier output voltage. Therefore, the PTX 12 must ramp up the power supply to match the actual rectifier output voltage to the target rectifier output voltage. As shown in FIG. 9A, in both profiles, the phase ramps down over time from PHASE_MAX (e.g., 50 degrees, where power transfer is minimum) to PHASE_MIN (e.g., 0 degrees, where power transfer is maximum). However, when the PTX 12 operates in gain linearization mode, the phase ramps down more quickly in profile 124.

[0081] 9B, for both profiles, the inverter voltage begins to ramp up when the phase reaches 0 degrees. In profile 126, the inverter voltage begins to ramp up at loop iteration L2 when the phase reaches 0 degrees. In profile 128, the inverter voltage begins to ramp up at loop iteration L1 when the phase reaches 0 degrees. Thus, the inverter voltage begins to ramp up sooner for profile 128 than for profile 126. The inverter voltage may also ramp up faster for profile 128 than for profile 126.

[0082] As shown in FIG. 9C, for both profiles, the actual rectifier output voltage ramps up over time. In profile 130, the actual rectifier output voltage has a discontinuity at loop iteration L2 when inverter phase regulation ends and inverter voltage regulation begins. In contrast, in profile 132, the actual rectifier output voltage does not have a discontinuity. Furthermore, the actual rectifier output voltage ramps up faster for profile 132 than for profile 130. V RECT may reach the target rectifier output voltage in fewer loop iterations in profile 132 than in profile 130.

[0083] Therefore, operating the PTX 12 in gain linearization mode may improve the speed of ramp-up (or ramp-down) in the power control loop and may avoid discontinuities in the actual rectifier output voltage during ramp-up (or ramp-down). Operating the PTX 12 in gain linearization mode may also unify the ramp-up / down speed across different circuit gains (e.g., caused by different position offsets between the PTX 12 and the PRX 24 and / or different load conditions at the PRX 24).

[0084] 10 is a state diagram illustrating how PTX 12 may operate in a selected one of gain linearization mode 142 (sometimes referred to as variable gain coefficient mode 142) and constant gain mode 144 (sometimes referred to as constant gain coefficient mode 144). Control circuitry 16 may place PTX 12 in one of modes 142 and 144 based on one or more factors, such as the device type of PRX 24 (e.g., whether the PRX is a cell phone, a watch, or other type of device), the state of charge of a battery in PRX 24 (as reported by PRX 24 to PTX 12), etc. In yet another possible example, PRX 24 may send instructions to PTX 12 to place PTX 12 into one of modes 142 and 144 based on one or more factors such as the device type of PTX 12 (e.g., whether the PTX is a standalone power adapter, a wireless charging mat or pack connected to a power adapter or other device by a cable, a mobile phone, or other type of device), the charge state of battery 34 within PRX 24, etc.

[0085] When the PRX 24 controls whether the PTX 12 operates in mode 142 or mode 144, the mode selection information may be included in the same packet as the XCEV, as needed (e.g., a bit in the XCE packet may identify whether the PTX 12 should operate in gain linearization mode 142 or constant gain mode 144). Alternatively, the mode selection information may be included in a separate packet from the XCEV. An XCE packet with an updated XCEV may be sent by the PRX 24 with each iteration of the control loop. In contrast, an additional packet with mode selection information may be sent by the PRX 24, separate from the XCE packet, only when the PRX 24 wants to change the mode of the PTX 12.

[0086] Similarly, PRX 24 is the g for PTX 12 factor When choosing the size of g factor The size of g may be included in the same packet as the XCEV if desired (e.g., a dedicated bit in the XCE packet may be used to factor (You may also identify the magnitude of g factor The magnitude of g may be included in a packet separate from the XCEV. An XCE packet with the updated XCEV may be sent by the PRX 24 with each iteration of the control loop. In contrast, g factor An additional packet with a size of g is sent by the PRX 24 separately from the XCE packet. factor It can be sent by the PRX 24 separately from the XCE packet only if it wants to change the size of the

[0087] As an example, the PRX 24 may transmit a first packet including mode selection information to the PTX 12 during a handshake operation with the PTX 12 and before the power transfer phase starts. factor A second packet containing the magnitude of the power transfer signal may be sent to the PTX 12. The PRX 24 may then repeatedly send XCE packets to the PTX 12 during the power transfer phase.

[0088] According to one embodiment, a non-transitory computer-readable storage medium can store one or more programs configured to be executed by one or more processors of an electronic device configured to transfer wireless power with an additional electronic device. The electronic device can include a wireless power transmission coil and an inverter configured to provide an AC drive signal to the wireless power transmission coil, and the one or more programs can include instructions to receive information from the additional electronic device, including power feedback information, and adjust at least one operating characteristic of the inverter using a variable gain factor and the power feedback information.

[0089] According to one embodiment, a non-transitory computer-readable storage medium can store one or more programs configured to be executed by one or more processors of an electronic device configured to receive wireless power from an additional electronic device. The electronic device can include a wireless power transmission coil and a rectifier connected to the wireless power transmission coil having a target output voltage and an actual output voltage, the one or more programs including instructions to determine a first value proportional to a difference between the target output voltage and the actual voltage divided by the actual output voltage, send the first value to the additional electronic device, and send a second value between 0 and 1 to the additional electronic device, the second value affecting a magnitude of a change in wireless power output by the additional electronic device in response to the sent first value.

[0090] According to one embodiment, a method of operating an electronic device configured to receive wireless power from an additional electronic device, the electronic device comprising a wireless power transmission coil and a rectifier connected to the wireless power transmission coil and having a target output voltage and an actual output voltage, the method may include: determining a first value proportional to a difference between the target output voltage and the actual voltage divided by the actual output voltage; transmitting the first value to the additional electronic device; and transmitting a second value between 0 and 1 to the additional electronic device, the second value affecting the magnitude of a change in wireless power output by the additional electronic device in response to the transmitted first value.

[0091] According to one embodiment, there is provided an electronic device configured to wirelessly transfer power with an additional electronic device, the electronic device including: a wireless power transfer coil; an inverter configured to provide an AC drive signal to the wireless power transfer coil; and control circuitry configured to receive information from the additional electronic device, the information including power feedback information, and to adjust at least one operating characteristic of the inverter using a variable gain factor and the power feedback information.

[0092] According to another embodiment, adjusting at least one operating characteristic of the inverter optionally includes adjusting an input voltage to the inverter, the magnitude of the adjustment to the input voltage being determined using a variable gain factor and power feedback information from the additional electronic device.

[0093] According to another embodiment, adjusting at least one operating characteristic of the inverter optionally includes adjusting an operating phase of the inverter, the magnitude of the adjustment to the operating phase being determined using a variable gain factor and power feedback information from the additional electronic device.

[0094] According to another embodiment, adjusting at least one operating characteristic of the inverter optionally includes adjusting a selected one of a duty cycle and a wireless power transmission signal frequency, wherein the magnitude of the adjustment to the selected one of the duty cycle and the wireless power transmission signal frequency is determined using a variable gain factor and power feedback information from the additional electronic device.

[0095] According to another embodiment, the control circuit is optionally further configured to adjust at least one operating characteristic of the inverter using a predetermined gain and the power feedback information, the predetermined gain optionally being predetermined prior to coupling between the electronic device and the additional electronic device.

[0096] According to another embodiment, the control circuit is optionally configured to select one of a predetermined gain and a variable gain factor to adjust at least one operating characteristic of the inverter based on information from the additional electronic device.

[0097] According to another embodiment, the control circuit is optionally configured to adjust at least one operating characteristic of the inverter using a predetermined gain in a constant gain mode, the control circuit is optionally configured to adjust at least one operating characteristic of the inverter using a variable gain coefficient in a gain linearization mode, the power feedback information optionally includes a value proportional to a difference between a target rectifier output voltage of the additional electronic device and an actual rectifier output voltage of the additional electronic device, and adjusting the at least one operating characteristic of the inverter optionally includes iteratively adjusting the at least one operating characteristic of the inverter until the actual rectifier output voltage matches the target rectifier output voltage in the additional electronic device, and in the gain linearization mode, the actual rectifier output voltage optionally matches the target rectifier output voltage in the additional electronic device faster than in the constant gain mode.

[0098] According to another embodiment, the control circuit is optionally configured to determine a variable gain factor as a function of at least the inverter voltage, the inverter phase, and a value between 0 and 1.

[0099] According to another embodiment, the control circuitry is optionally configured to receive values ​​from an additional electronic device.

[0100] According to another embodiment, the control circuit is optionally configured to determine the additional variable gain factor as a function of at least the variable gain factor, the minimum inverter voltage, and the inverter phase.

[0101] According to another embodiment, the control circuit optionally comprises a control circuit having a function of:

number

number

[0102] According to another embodiment, the power feedback information optionally includes a value proportional to a difference between a target rectifier output voltage of the additional electronic device and an actual rectifier output voltage of the additional electronic device.

[0103] According to another embodiment, adjusting at least one operating characteristic of the inverter optionally includes adjusting an input voltage to the inverter, the magnitude of the adjustment to the input voltage being determined by multiplying a variable gain factor by a value.

[0104] According to another embodiment, adjusting at least one operating characteristic of the inverter optionally includes adjusting an operating phase of the inverter, the magnitude of the adjustment to the operating phase optionally being determined by multiplying a variable gain factor by a value.

[0105] According to one embodiment, there is provided a method of operating an electronic device configured to transmit wireless power with an additional electronic device including a wireless power transmission coil and an inverter configured to provide an AC drive signal to the wireless power transmission coil, the method including receiving information from the additional electronic device including power feedback information, and adjusting at least one operating characteristic of the inverter using a variable gain factor and the power feedback information.

[0106] According to one embodiment, there is provided an electronic device configured to receive wireless power from an additional electronic device, the electronic device including: a wireless power transmission coil; a rectifier connected to the wireless power transmission coil, the rectifier having a target output voltage and an actual output voltage; and control circuitry configured to determine a first value proportional to a difference between the target output voltage and the actual voltage divided by the actual output voltage, transmit the first value to the additional electronic device, and transmit to the additional electronic device a second value between 0 and 1, the second value affecting a magnitude of a change in wireless power output by the additional electronic device in response to the transmitted first value.

[0107] According to another embodiment, the control circuitry is optionally configured to repeatedly transmit a first packet including a first value using the wireless power transmission coil during the power transfer phase, and the control circuitry is optionally configured to transmit a second packet including a second value using the wireless power transmission coil before the power transfer phase.

[0108] According to another embodiment, the control circuitry is optionally configured to transmit, using the wireless power transmission coil, a first packet including both the first value and the second value.

[0109] According to another embodiment, the control circuitry is optionally configured to send information to the additional electronic device to operate the additional electronic device in a selected one of a gain linearization mode and a constant gain mode.

[0110] According to another embodiment, the control circuit is optionally configured to determine the magnitude of the second value based at least in part on the magnitude of the change in the actual output voltage.

[0111] The above is merely exemplary and various modifications may be made to the described embodiments. The above embodiments may be implemented individually or in any combination.

Claims

1. 1. An electronic device configured to transmit wireless power to an additional electronic device, the electronic device comprising: a wireless power transmission coil; an inverter configured to provide an AC drive signal to the wireless power transmission coil; a control circuit, wherein the control circuit receiving information from the additional electronic device, the information including power feedback information; an electronic device configured to adjust at least one operating characteristic of the inverter using a variable gain factor and the power feedback information;

2. 2. The electronic device of claim 1, wherein adjusting the at least one operating characteristic of the inverter includes adjusting an input voltage to the inverter, the magnitude of the adjustment to the input voltage being determined using the variable gain factor and the power feedback information from the additional electronic device.

3. 2. The electronic device of claim 1, wherein adjusting the at least one operating characteristic of the inverter includes adjusting an operating phase of the inverter, the magnitude of the adjustment to the operating phase being determined using the variable gain factor and the power feedback information from the additional electronic device.

4. 2. The electronic device of claim 1, wherein adjusting the at least one operating characteristic of the inverter includes adjusting a selected one of a duty cycle and a wireless power transmission signal frequency, and wherein the magnitude of the adjustment to the selected one of the duty cycle and the wireless power transmission signal frequency is determined using the variable gain factor and the power feedback information from the additional electronic device.

5. The control circuit 10. The electronic device of claim 1, further configured to adjust the at least one operating characteristic of the inverter using a predetermined gain and the power feedback information, the predetermined gain being predetermined prior to coupling between the electronic device and the additional electronic device.

6. 6. The electronic device of claim 5, wherein the control circuit is configured to select one of the predetermined gain and the variable gain factor to adjust the at least one operating characteristic of the inverter based on the information from the additional electronic device.

7. 6. The electronic device of claim 5, wherein the control circuit is configured to adjust the at least one operating characteristic of the inverter using the predetermined gain in a constant gain mode, the control circuit is configured to adjust the at least one operating characteristic of the inverter using the variable gain coefficient in a gain linearization mode, the power feedback information includes a value proportional to a difference between a target rectifier output voltage of the additional electronic device and an actual rectifier output voltage of the additional electronic device, and adjusting the at least one operating characteristic of the inverter includes iteratively adjusting the at least one operating characteristic of the inverter until the actual rectifier output voltage matches the target rectifier output voltage at the additional electronic device, and the actual rectifier output voltage matches the target rectifier output voltage at the additional electronic device faster in the gain linearization mode than in the constant gain mode.

8. The electronic device of claim 1 , wherein the control circuit is configured to determine the variable gain factor as a function of at least an inverter voltage, an inverter phase, and a value between 0 and 1.

9. The electronic device of claim 8 , wherein the control circuitry is configured to receive the value from the additional electronic device.

10. The electronic device of claim 8 , wherein the control circuit is configured to determine an additional variable gain factor as a function of at least the variable gain factor, a minimum inverter voltage, and the inverter phase.

11. The control circuit is [Equation 1] where VIN_gain is the variable gain coefficient and V IN is the inverter voltage, θ is the inverter phase, n is a constant proportional to the bit length of the power feedback information, and g target is the value, and the control circuit is [Equation 2] 11. The electronic device of claim 10, configured to determine the additional variable gain factor using an equation where Phase_gain is the additional variable gain factor, VIN_gain is the variable gain factor, VIN_MIN is the minimum inverter voltage, and θ is the inverter phase.

12. 2. The electronic device of claim 1, wherein the power feedback information comprises a value proportional to a difference between a target rectifier output voltage of the additional electronic device and an actual rectifier output voltage of the additional electronic device.

13. 13. The electronic device of claim 12, wherein adjusting the at least one operating characteristic of the inverter includes adjusting an input voltage to the inverter, the magnitude of the adjustment to the input voltage being determined by multiplying the variable gain factor by the value.

14. 13. The electronic device of claim 12, wherein adjusting the at least one operating characteristic of the inverter includes adjusting an operating phase of the inverter, the magnitude of the adjustment to the operating phase being determined by multiplying the variable gain factor by the value.

15. 1. A method of operating an electronic device configured to transmit wireless power to a further electronic device, the electronic device comprising: a wireless power transmission coil; and an inverter configured to provide an AC drive signal to the wireless power transmission coil, the method comprising: receiving information from the additional electronic device, the information including power feedback information; and adjusting at least one operating characteristic of the inverter using a variable gain factor and the power feedback information.

16. 1. An electronic device configured to receive wireless power from an additional electronic device, the electronic device comprising: a wireless power transmission coil; a rectifier connected to the wireless power transmission coil, the rectifier having a target output voltage and an actual output voltage; a control circuit, wherein the control circuit determining a first value proportional to the difference between the target output voltage and the actual voltage divided by the actual output voltage; transmitting the first value to the additional electronic device; and transmitting to the additional electronic device a second value between 0 and 1, the second value affecting a magnitude of a change in wireless power output by the additional electronic device in response to the transmitted first value.

17. 17. The electronic device of claim 16, wherein the control circuitry is configured to repeatedly transmit a first packet including the first value using the wireless power transmission coil during a power transfer phase, and wherein the control circuitry is configured to transmit a second packet including the second value using the wireless power transmission coil before the power transfer phase.

18. 17. The electronic device of claim 16, wherein the control circuitry is configured to transmit, using the wireless power transmission coil, a first packet comprising both the first value and the second value.

19. 17. The electronic device of claim 16, wherein the control circuitry is configured to send information to the additional electronic device to operate the additional electronic device in a selected one of a gain linearization mode and a constant gain mode.

20. 17. The electronic device of claim 16, wherein the control circuitry is configured to determine the magnitude of the second value based at least in part on a magnitude of the change in the actual output voltage.

Images