Wireless power receiving device

Abstract

This disclosure relates to a feedback control scheme for wireless power transmission circuitry. Portable electronic devices such as cellular phones, wristwatches, tablets, wireless earbuds, and other portable devices use batteries. These batteries can be charged using a wireless power system. For example, a user can place devices such as tablets and cellular phones on a wireless charging pad or wireless charging mat to wirelessly charge these devices. The wireless power system includes a power transmitting device and a power receiving device. Coils in the power transmitting and receiving devices are used to transmit and receive wireless power signals. The coupling between the transmitting and receiving coils can affect the wireless charging efficiency and the power generated in the receiving device. A feedback control scheme is disclosed herein to optimize the efficiency of the wireless power transmission system.

Description

[0001] priority

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 212,252, filed June 18, 2021, entitled “FEEDBACK CONTROL SCHEMES FOR WIRELESS POWER TRANSFER CIRCUITS”, pursuant to 35 USC §119(e), which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure generally relates to wireless charging, and more specifically to a feedback control scheme for wireless power transfer in a wireless power system. Background Technology

[0004] Portable electronic devices such as cell phones, wristwatches, tablets, wireless earbuds, and other portable devices use batteries. These batteries can be charged using battery charging systems. To improve user convenience, wireless power systems have been developed that allow batteries in portable electronic devices to be charged wirelessly. Coils in the power transmitting and receiving devices are used to transmit and receive wireless power signals. The coupling between the transmitting and receiving coils can affect wireless charging efficiency and the power generated in the receiving device.

[0005] The foregoing background information is intended to assist the reader only and is not intended to limit the innovations described herein. Therefore, the foregoing should not be used to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential for implementing the innovations described herein. Specific implementations and applications of the innovations described herein are defined by the appended claims. Summary of the Invention

[0006] A wireless power system includes a power transmitting device and a power receiving device. Coils in both the transmitting and receiving devices are used to transmit and receive wireless power signals. The coupling between the transmitting and receiving coils can affect wireless charging efficiency and the power generated in the receiving device.

[0007] An exemplary wireless power receiving device can be configured to receive a wireless power signal from a wireless power transmitting device. The wireless power receiving device may include a wireless power transmitting coil. Additionally, the receiving device includes a rectifier circuit coupled to the wireless power transmitting coil and configured to rectify the signal from the wireless power transmitting coil into an output voltage. The receiving device also includes control circuitry configured to adjust the rectifier output voltage at a target rectifier output voltage level, receive a status message indicating the inverter input voltage from the wireless power transmitting device, and adjust the target output voltage based on the status of the inverter input voltage.

[0008] Another exemplary wireless power receiving device may be configured to receive a wireless power signal from a wireless power transmitting device. The wireless power receiving device may include a wireless power transmitting coil. Additionally, the receiving device includes a rectifier circuit coupled to the wireless power transmitting coil and configured to rectify the signal from the wireless power transmitting coil into an output voltage. The receiving device also includes control circuitry configured to measure characteristics of the rectifier circuitry, determine a target rectifier output voltage level based on the measured characteristics of the rectifier circuitry, and dynamically adjust the rectifier output voltage at the target rectifier output voltage level.

[0009] Another exemplary wireless power receiving device may be configured to receive a wireless power signal from a wireless power transmitting device. The wireless power receiving device may include a wireless power transmission coil. Additionally, the receiving device includes a rectifier circuit coupled to the wireless power transmission coil and configured to rectify the signal from the wireless power transmission coil into an output voltage. The receiving device also includes control circuitry configured to adjust the rectifier output voltage at a target rectifier output voltage level. The control circuitry may also query the wireless power transmitting device for information indicating operating conditions of the inverter of the wireless power transmitting device, wherein the wireless power transmission coil is receiving a wireless power signal transmitted by the wireless power transmitting device using the inverter. Attached Figure Description

[0010] The foregoing overview and the following detailed description are better understood when read in conjunction with the accompanying drawings. In the drawings, numerous specific details are set forth for illustrative purposes to provide an understanding of variations in the implementation of the disclosed technology. However, this disclosure may take many different forms and should not be considered limited to the specific examples disclosed in the drawings. In practice, similar figures always refer to similar elements. In the drawings:

[0011] Figure 1 This is a schematic diagram of an exemplary wireless power system according to one aspect of this disclosure.

[0012] Figure 2This is an exploded view of an exemplary wireless power receiving device having a coil for receiving wireless power, according to one aspect of this disclosure.

[0013] Figure 3A This is a perspective view of an exemplary wireless power transmitting device having a coil for charging a wireless power receiving coil, according to one aspect of this disclosure.

[0014] Figure 3B yes Figure 3A A top view of the wireless power transmitting device.

[0015] Figure 4 It is used in Figure 1 The diagram illustrates an example of a prior art control method for wireless power transmission between a power transmitting device and a power receiving device in a wireless power system.

[0016] Figure 5 This is an illustrative diagram of a feedback control scheme for a wireless power transmission system according to one aspect of this disclosure.

[0017] Figure 6 This is an illustrative diagram of another feedback control scheme for a wireless power transmission system according to one aspect of this disclosure.

[0018] Figure 7 Is using Figure 5 and Figure 6 The flowchart illustrates an exemplary control loop algorithm implemented in a power receiving device of a wireless power transmission system using the feedback control scheme shown. Detailed Implementation

[0019] Portable electronic devices such as cell phones, smartwatches, tablets, wireless earbuds, and other portable devices use batteries. These batteries can be charged using wireless charging systems. For example, users can place devices such as smartwatches and cell phones on a wireless charging pad to wirelessly charge them.

[0020] Figure 1 An exemplary wireless power system is illustrated. The wireless power system 8 includes electronic devices 10. Electronic devices 10 include electronic devices that transmit wireless power and / or electronic devices that receive wireless power. Because battery charging is a common use of the received power, the wireless power transmission operation in system 8 is sometimes referred to as a battery charging operation. However, if needed, power can also be provided to a receiving device to operate a display or other circuitry within the receiving device without charging the battery. Therefore, wireless power can be used to charge batteries in electronic devices, as well as to power other device components.

[0021] Charging can be performed by wirelessly transmitting power from a power transmitting device (such as device 12) to a power receiving device (such as device 24), for example, using inductive charging. Coils in both the power transmitting and receiving devices are used to transmit and receive wireless power signals. Figure 1 In the example, power is being transmitted wirelessly using wireless power signal 44. The wireless charging efficiency of device 24 is partly affected by the coupling between coil 42 on device 12 and coil 48 on device 24 (also referred to herein as the coupling between transmitting device 12 and receiving device 24).

[0022] The physical alignment of coils 42 and 48 in the X, Y, and Z dimensions affects electromagnetic coupling. An offset of x=0, y=0 means that the centers of coils 42 and 48 are aligned in the XY plane. An offset of z=0 can mean that the distance between the surfaces of the two devices containing coils 42 and 48 is minimized. For example, neither power transmitting device 12 nor power receiving device 24 is separated. An offset (x, y, z) = (0, 0, 0) can be called the optimal coupling condition. Alternatively, an offset (r, z) = (0, 0) can also be called the optimal coupling condition, where "r" is the offset radius between the centers of coils 42 and 48.

[0023] The electromagnetic coupling between coil 42 on device 12 and coil 48 on device 24 can be designed to operate within positional tolerances. In one example, the wireless power delivery system can be optimized for alignment within 5 mm in the XY plane with respect to the centers of coils 42 and 48, and the distance between the surfaces of devices 12 and 24 is within 5 mm in the Z direction. This design guideline can be referred to as a “5 mm by 5 mm” offset. In this example, “good” coupling occurs when the center of coil 48 of power receiving device 24 is aligned with the center of coil 42 of power transmitting device 12 within 5 mm by 5 mm. In this orientation, good charging can be achieved because the system is designed to transmit full power from device 12 to device 24 when the coils are offset by + / - 5 mm. Continuing with the 5 mm by 5 mm design example, coupling where the power transmitting coil and the power receiving coil are offset beyond the + / - 5 mm design guideline can be classified as “poor” coupling. Those skilled in the art will recognize that the wireless power transmission system is not limited to this exemplary location tolerance range and can be designed with alternative ranges (e.g., + / -1mm, + / -2mm, + / -3mm, + / -4mm, + / -6mm or greater) without departing from the scope and spirit of the invention as described herein.

[0024] Good coupling between the transmitting and receiving coils promotes efficient wireless power transfer. Poor coupling between the transmitting and receiving coils can negatively impact wireless charging efficiency and the power generated in the receiving device 24. This paper discloses a feedback control scheme to optimize the efficiency of the wireless power transfer system.

[0025] During operation of System 8, the wireless power transmitting device 12 wirelessly transmits power to one or more wireless power receiving devices, such as device 24. The wireless power receiving device may include electronic devices such as watches, cellular phones, tablets, laptops, earphones, battery cases for earphones and other devices, tablet pens (e.g., styluses), and other input-output devices (e.g., accessory devices), wearable devices, or other electronic equipment. The wireless power transmitting device may be an electronic device such as a wireless charging pad or wireless charging mat having a charging surface (e.g., a flat charging surface) for receiving the portable device to be charged, a tablet or other portable electronic device with wireless power transmitting circuitry (e.g., one of device 24 with wireless power transmitting circuitry), or other wireless power transmitting devices. The wireless power receiving device uses the power from the wireless power transmitting device to power internal components and to charge the internal battery.

[0026] like Figure 1 As shown, the wireless power transmitting device 12 includes control circuitry 16. The wireless power receiving device 24 includes control circuitry 30. Control circuitry in system 8, such as control circuitry 16 and control circuitry 30 (and / or control circuitry in other devices 10), is used in the operation of system 8. This control circuitry may include processing circuitry associated with a microprocessor, power management unit, baseband processor, digital signal processor, microcontroller, and / or application-specific integrated circuit with processing circuitry. The processing circuitry implements the desired control and communication features in devices 12 and 24. For example, the processing circuitry may be used to operate the control loops discussed herein, select coils, adjust the phase and amplitude of coil drive signals, determine power transmission levels, process sensor data and other data, process user input, handle negotiations between devices 12 and 24, send and receive in-band and out-of-band data, perform measurements, start and stop charging operations, turn device 10 on and off, put device 10 into a low-power sleep mode, and otherwise control the operation of system 8.

[0027] The control circuitry in system 8 can be configured to perform operations within system 8 using hardware (e.g., dedicated hardware or circuitry), firmware, and / or software. Software code used to perform operations within system 8 is stored on a non-transitory computer-readable storage medium (e.g., a tangible computer-readable storage medium) in the control circuitry 8. Software code may sometimes be referred to as software, data, program instructions, commands, 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 disk drives (e.g., disk 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 can be executed on the processing circuitry of device 10 (e.g., control circuitry 16 and / or 30). The processing circuitry may include an application-specific integrated circuit (ASIC) with processing circuitry, one or more microprocessors, a central processing unit (CPU), or other processing circuitry.

[0028] The power transmitting device 12 can be a standalone power adapter (e.g., a wireless charging pad or wireless charging tray including power adapter circuitry), a wireless charging pad or wireless charging tray coupled to a power adapter or other equipment via a cable, a portable electronic device (cellular phone, tablet, laptop, etc.), equipment integrated into furniture, vehicles, or other systems, or other wireless power transmission equipment. The wireless power transmitting device 12 is sometimes described herein as an exemplary configuration of a wireless charging pad, wireless charging tray, or portable electronic device.

[0029] The power receiving device 24 may be a portable electronic device, such as a wristwatch, cellular phone, laptop computer, tablet computer, accessory (such as earphones), tablet computer input device (such as a wireless tablet pen), battery case, or other electronic equipment. The power transmitting device 12 may be coupled to a wall socket (e.g., an AC power source), may have a battery for power supply, and / or may have another power source. The power transmitting device 12 may have an AC-DC power converter, such as an AC-DC power converter 14, for converting AC power from the wall socket or other power source to DC power. In some configurations, the AC-DC power converter 14 may be housed in a separate housing (e.g., a power brick housing) from the housing of device 12 (e.g., a wireless charging pad housing or a portable electronic device housing), and a cable may be used to couple DC power from the power converter to device 12. The DC power may be used to power control circuitry 16.

[0030] During operation, the controller in control circuitry 16 can use power transmitting circuitry 52 to transmit wireless power to power receiving circuitry 54 of device 24. Power transmitting circuitry 52 may have a switching circuit (e.g., an inverter circuitry 60 formed of transistors) that is switched on or off based on a control signal provided by control circuitry 16 to generate an AC current signal passing through one or more transmitting coils 42. Coils 42 may be arranged as a planar coil array (such as in a configuration where device 12 is a wireless charging pad), or in other configurations. In some arrangements, device 12 may have a single coil. In arrangements where device 12 has multiple coils, the coils may be arranged in one or more layers. Coils in different layers may or may not overlap each other.

[0031] When an AC current passes through one or more coils 42, a time-varying electromagnetic (e.g., magnetic) field (signal 44) is generated, which is received by one or more corresponding receiver coils, such as coil 48, in the power receiving device 24. When the time-varying electromagnetic field is received by coil 48, a corresponding alternating current is induced in coil 48. A rectifier circuit (such as rectifier 50) containing rectifier components (such as synchronous rectifier metal-oxide-semiconductor transistors arranged in a bridging network) converts the received AC signal from coil 48 into a DC voltage signal for powering the device 24.

[0032] The DC voltage generated by rectifier 50 can be used to power (charge) energy storage devices such as battery 58, and can also be used to power other components in device 24. For example, device 24 may include input-output devices 56, such as displays, touch sensors, communication circuitry, audio components, sensors, components that generate electromagnetic signals sensed by touch sensors in tablet computers or other devices with touch sensors (e.g., to provide pen input), and other components, and these components may be powered by the DC voltage generated by rectifier 50 (and / or by the DC voltage generated by battery 58 or other energy storage devices in device 24).

[0033] Device 12 and / or device 24 can communicate wirelessly (e.g., using in-band and out-of-band communication). Device 12 may, for example, have a wireless transceiver (TX / RX) circuitry 40 that wirelessly transmits out-of-band signals to device 24 using an antenna. Wireless transceiver circuitry 40 can be used to wirelessly receive out-of-band signals from device 24 using an antenna. Device 24 may have a wireless transceiver circuitry 46 that transmits out-of-band signals to device 12. Receiver circuitry in wireless transceiver 46 can use an antenna to receive out-of-band signals from device 12. In some configurations, device 10 can communicate over a local area network and / or a wide area network (e.g., the Internet).

[0034] Wireless transceiver circuit 40 uses one or more coils 42 to transmit in-band signals to wireless transceiver circuit 46, which are received by wireless transceiver circuit 46 using coil 48. Any suitable modulation scheme can be used to support in-band communication between device 12 and device 24. In one exemplary configuration, frequency shift keying (FSK) is used to transfer in-band data from device 12 to device 24, and amplitude shift keying (ASK) is used to transfer in-band data from device 24 to device 12. During these FSK and ASK transmissions, power can be wirelessly transferred from device 12 to device 24. Other types of in-band communication can be used if desired.

[0035] During wireless power transmission operation, circuit 52 supplies an AC drive signal to one or more coils 42 at a given power transmission frequency. The power transmission frequency can be, for example, about 125 kHz, at least 80 kHz, at least 100 kHz, less than 500 kHz, less than 300 kHz, less than 150 kHz, a predetermined frequency between 80 kHz and 150 kHz, or other suitable wireless power frequencies. In some configurations, the power transmission frequency can be negotiated in communication between devices 12 and 24. In other configurations, the power transmission frequency can be fixed.

[0036] During wireless power transfer operation, while the power transmitting circuit 52 drives an AC signal into one or more of the coils 42 at the power transmitting frequency to generate an electromagnetic signal 44, the wireless transceiver circuit 40 can use FSK modulation to transmit data and information via the driving AC signal 44. In device 24, coil 48 is used to receive the electromagnetic signal 44. The power receiving circuit 54 uses the received signal on coil 48 and rectifier 50 to generate DC power. Simultaneously, the wireless transceiver circuit 46 uses FSK demodulation to extract the transmitted in-band data from signal 44. This method allows FSK data (e.g., FSK packets) to be transmitted in-band from device 12 to device 24 using coils 42 and 48, while simultaneously using coils 42 and 48 to wirelessly transfer power from device 12 to device 24. Other types of in-band communication between device 12 and device 24 can be used if desired.

[0037] In-band communication between device 24 and device 12 can utilize ASK modulation and demodulation techniques or other suitable in-band communication techniques. Wireless transceiver circuitry 46 transmits in-band data to device 12 by using a switch (e.g., one or more transistors coupling coil 48 in transceiver 46) to modulate the impedance of power receiving circuitry 54 (e.g., coil 48). This, in turn, modulates the amplitude of signal 44 and the amplitude of the AC signal passing through coil 42. Wireless transceiver circuitry 40 monitors the amplitude of the AC signal passing through coil 42 and uses ASK demodulation to extract the transmitted in-band data from these signals transmitted by wireless transceiver circuitry 46. ASK communication allows ASK data bits (e.g., a series of ASK packets) to be transmitted in-band from device 24 to device 12 using coils 48 and 42, while simultaneously using coils 42 and 48 to wirelessly deliver power from device 12 to device 24.

[0038] Control circuit 16 may include an external object measurement circuit 41 (sometimes referred to as an external object detection circuit or external object detection circuit) for detecting external objects on the charging surface associated with device 12. Circuit 41 can detect external objects such as coils, paperclips, and other metallic objects, and can detect the presence of wireless power receiving device 24. During object detection and characterization operations, external object measurement circuit 41 can be used to measure coil 42 to determine the presence of any device 24 on device 12 (e.g., whether the presence of device 24 on device 12 is suspected). Measurement circuit 43 in control circuit 30 can be used to perform current and voltage measurements in coil 48, and / or to perform other measurements on wireless power receiving circuit 54. Measurement circuit 41 in control circuit 16 can be used to perform current and voltage measurements in coil 42, and / or to perform other measurements on wireless power transmitting circuit 52. In cases where device 12 includes multiple coils 42, control circuit 16 can use each coil 42 to perform measurements sequentially and / or in parallel. The control circuit 16 can compare the measurements taken using the measurement circuit 41 with predetermined characteristics associated with the device 24 (e.g., predetermined characteristics associated with different types of devices 24 used by the control circuit 16 to identify the type of device 24 being charged).

[0039] Figure 2 An exploded view of an exemplary wireless power receiving device 24 is shown. Figure 2 As shown, the wireless power receiving device 24 includes a housing, such as a top housing 62 and a bottom housing 64 that can be fitted to define an internal cavity. The bottom housing 64 has a surface 74, also referred to herein as a rear surface 74, which is positioned on or above the charging surface 82 of the device 12 for wireless charging of the device 24. For example, during wireless charging, both the rear surface 74 and the charging surface 82 of the device 12 may be substantially parallel to each other. Figure 2The XY plane. A display screen (such as an OLED display) or other input-output device may be mounted on the top housing 64 on surface 72 (also referred to herein as the upper surface 74).

[0040] Device 24 includes one or more coils 48, which are located on a bottom housing 64 or within an internal cavity formed by a top housing 62 and a bottom housing 64. Housings 62 and 64 may comprise metallic, dielectric, or combinations of these and / or other materials. Device 24 may optionally include a ferromagnetic shield 66 and a thermal shield 65 near the coils 48. The thermal shield 65 may include a graphite layer or similar layer providing thermal insulation between the coils 48 and the battery and other components of device 24. The ferromagnetic shield 66 may be positioned between the power coils 48 and the thermal shield 65. The ferromagnetic shield 66 may act as a magnetic field shield for redirecting magnetic flux to achieve higher coupling with the coils 42 in the power transmitting device 12, which may improve charging efficiency. Device 24 may optionally include an adhesive component 67 for attaching the coils 48 to the bottom housing 64. The adhesive component 67 may be a monolithic adhesive material, such as pressure-sensitive adhesive (PSA). The coil 48 may optionally be attached to the bottom housing 64 within a cutout area 68, which is sized and shaped to house the coil 48.

[0041] In some cases, the user can place device 24 on the charging surface of device 12 such that the rear surface 74 of the bottom housing 64 lies flat on the charging surface. In this exemplary configuration, the central axis of coil 48 extends parallel to the central axis of coil 42 in device 12, and a magnetic field from coil 42 can pass through coil 48. The magnetic field induces a current in coil 48 for wirelessly charging device 24.

[0042] Figure 3A It is a perspective view, and Figure 3B This is a top view of a wireless power transmitting device 12 in an exemplary configuration. As shown, the wireless power transmitting device 12 may have a coil 42 at a charging surface 82 for transmitting wireless power to a coil 48 in a power receiving device 24. In one exemplary configuration, the device 12 is a wireless charging pad with a planar surface 84 opposite to the charging surface 82 and resting on a surface below, such as a desktop or other surface. A user can place the device 24 on the charging surface 82 to charge the device 24. The rear surface 74 of the device 24 ( Figure 2 The charging surface 82 is located in a plane that is substantially parallel to the XY plane of Figure 3 during wireless charging.

[0043] Device 12 can be used Figure 1The corresponding inverter 60 drives coil 42 to generate a magnetic field. When device 24 is placed on charging surface 82, the magnetic field passes through coil 48 and induces a current in coil 48 for wirelessly charging device 24. The electromagnetic coupling between coils 42 and 48 is optimized when coil 48 is centered around coil 42. However, the size of coil 42 allows for certain positional tolerances along the X and Y axes of FIG3 for placing device 24 on charging surface 82. As noted above, the wireless charging efficiency of device 24 is partly determined by the coupling between coil 42 on device 12 and coil 48 on device 24.

[0044] Figure 4 This is an example diagram illustrating the design constraints of the existing technology control method 400. Figure 4 Plot the voltage on the Y-axis and the power on the X-axis. Figure 4 This includes an exemplary rectifier output voltage (“Vrect”) load line 410A, which occurs under good coupling between the power transmitting device 12 and the power receiving device 24; and an exemplary Vrect load line 410B, which occurs under poor coupling between the power transmitting device 12 and the power receiving device 24, both occurring when the inverter output voltage of the power transmitting device 12 is at its maximum level. In the control method, the power receiving device attempts to regulate the rectifier output voltage at a constant target level 430. Because the control loop can reduce the inverter input voltage to bring Vrect to the target level, regulation can be achieved in the region where load lines 410A and 410B are above the regulation target 430. Because the inverter input voltage cannot be further increased, regulation cannot be achieved in the region where load line 410B is below the target level 430. Under good coupling, the system can achieve full power at 440A. However, under poor coupling conditions, the system can only achieve reduced power at 440B because it is constrained by the maximum available inverter input voltage of 420 and the weak magnetic coupling between the wireless power transmitter and receiver.

[0045] Figure 5 This is an illustrative diagram of a feedback control scheme for a wireless power transmission system according to one aspect of this disclosure. The control loop implemented in the power receiving device 24 regulates the rectifier output voltage at a target level, and allows the target rectifier output voltage to fold back (i.e., allows the target rectifier output voltage level to decrease) when the inverter input voltage of the power transmitting device is at the maximum inverter input voltage level and the load increases.

[0046] Figure 5 Plot the voltage on the Y-axis and the power on the X-axis. Figure 5Includes an exemplary rectifier output voltage (“Vrect”) load line 510, which occurs when the power transmitter inverter input voltage is at its maximum level, in the event of poor coupling between the power transmitter 12 and the power receiver 24. As you move along the X-axis from left to right, the load shown in load line 510 transitions from a light load to a heavy load.

[0047] Curve 520 plots the inverter input voltage of the power transmitting device. Curve 520 includes a first section 520A, where the inverter input voltage ramps up to the maximum inverter input voltage at 522 as the load, represented by load line 510, increases. As discussed below, the control loop can regulate the rectifier output voltage at the target level in this region of the inverter input voltage curve 520 (i.e., Vrect regulation is possible for the power receiving device). Curve 520 includes a second section 520B, where Vrect regulation is not possible because the inverter input voltage is at its maximum level and cannot be increased further. Further increasing the load power will cause Vrect to drop below the target level 530.

[0048] Curve 530 plots the target output voltage of the rectifier in the power receiving device. As shown, curve 530 includes a first portion 530A, where the power receiving device adjusts the rectifier output voltage at the target rectifier output voltage level as the load increases along load line 510. Curve 530 includes a second portion 530B, where the power receiving device operates in a target rectifier output voltage foldback mode, triggered at 532 when the inverter input voltage of the power transmitting device is at its maximum level and the load continues to increase. The target rectifier output voltage foldback mode allows the target rectifier output voltage level to decrease, and as the load further increases along line 510, the control loop adaptively adjusts the target rectifier output voltage to the new target rectifier output voltage level. When in target rectifier output voltage foldback mode, the power receiving device control circuit 30 may require the target rectifier output voltage not to drop below a predetermined minimum foldback rectifier output voltage level, thereby ensuring that rectifier 50 produces at least the minimum rectifier output power.

[0049] The target rectifier output voltage foldback mode control loop algorithm is implemented in the power receiving device 24. During wireless power transmission, the power transmitting device 12 can convey information indicating the inverter input voltage state to the power receiving device 24. For example, the information could be a message indicating that the inverter input voltage is at the maximum inverter input voltage level. Alternatively, the information could identify the inverter input voltage value. Communication can be performed in a packet carrying the inverter input voltage information. In another example, the information could be a bit flag in an existing data packet to indicate whether the inverter input voltage has reached its maximum level. Communication from the power transmitter 12 to the power receiver 24 can be performed using Frequency Shift Keying (FSK) technology as discussed above. Alternatively, other types of in-band or out-of-band communication can be used if desired.

[0050] In another example, power receiving device 24 may query power transmitting device 12 for information indicating the operating conditions of the inverter of the power transmitting device, wherein the wireless power transmission coil 48 is receiving a wireless power signal transmitted by the wireless power transmitting device 12 using the inverter. Additionally, the information may include a state indicating whether the inverter of the wireless power transmitting device 12 is operating at its maximum input voltage. If the power transmitting device 12 responds to the power receiving device 24's indication that the inverter input voltage is at its maximum level, then, as discussed above, the power receiving device 24 may trigger a target rectifier output voltage foldback mode to adaptively adjust the target rectifier output voltage when the inverter input voltage is at its maximum level.

[0051] Figure 6 This is an illustrative diagram of another feedback control scheme 600 for a wireless power transmission system according to one aspect of this disclosure. Control scheme 600 improves charging efficiency at light loads and includes the target rectifier output voltage foldback mode discussed above. Light load charging efficiency can be improved by reducing the inverter input voltage of the power transmitting device for light loads. A control loop implemented in the power receiving device 24 dynamically controls the target rectifier output voltage based on the output power or output current of the power receiving device rectifier. As discussed below, the target rectifier output voltage level is lower at light loads and increases to a higher target rectifier output voltage level as the load increases to a heavy load. The load and the target rectifier output voltage can depend on the operating conditions of the power receiving device 24. Exemplary operating conditions include the battery's state of charge, whether the device is playing video or running power-intensive applications such as video games. The target rectifier output voltage function (curve 630) can be designed for optimal coupling conditions and allows the target rectifier output voltage to fold back under poor coupling conditions, as shown in section 630C of the target rectifier output voltage function curve.

[0052] Figure 6Plot the voltage on the Y-axis and the power on the X-axis. Figure 6 Includes an exemplary rectifier output voltage (“Vrect”) load line 610, which occurs under conditions of poor coupling between the power transmitting device 12 and the power receiving device 24 when the power transmitting device inverter input voltage is at its maximum level. As you move along the X-axis from left to right, the load shown in load line 610 transitions from a light load to a heavy load.

[0053] Curve 620 plots the inverter input voltage of the power transmitting device. Curve 620 includes a first portion 620A, where the inverter input voltage is at a lower level for light loads, as shown in the leftmost portion of load line 610. Curve 620 includes a second portion 620B, where the inverter input voltage increases from a lower level to the maximum inverter input voltage level at 622 as the load represented in load line 610 transitions from light to heavy load. Curve 620 includes a third portion 620C, which represents the operating condition where the inverter input voltage is at the maximum inverter input voltage level.

[0054] Curve 630 plots the target output voltage of the power receiving device rectifier as the rectifier output power varies. As shown, curve 630 includes a first portion 630A where the rectifier output power is lower, and the rectifier output voltage is designed to be regulated at the minimum target rectifier output voltage level for light loads, as shown in the leftmost portion of load line 610. Because the inverter input voltage is maintained at a lower voltage level (i.e., the first portion 620A of the inverter input voltage curve), regulating the rectifier output voltage at the minimum target rectifier output voltage level improves charging efficiency at light loads.

[0055] Curve 630 includes the second part 630B and the third part 630B. 1 The rectifier output power is increasing, and the target rectifier output voltage is designed to increase from the minimum target rectifier output voltage level to the maximum target rectifier output voltage level 634 as the load transitions from a light load to a heavy load. However, due to poor coupling between the power transmitter 12 and the power receiver 24, the power receiver may not be able to operate in the third part 630B. 1The rectifier output voltage is adjusted at the target rectifier output voltage level shown because the power transmitter inverter input voltage is at the maximum inverter input voltage level. In this case, the fourth part 630C of curve 630 shows the power receiving device operating in target rectifier output voltage foldback mode, which is triggered at 632 when the power transmitter inverter input voltage is at its maximum level and the load along line 610 continues to increase. Target rectifier output voltage foldback mode allows the target rectifier output voltage level to drop, and as the load along line 610 increases further, the control loop adaptively adjusts the target rectifier output voltage to the new target rectifier output voltage level. When in target rectifier output voltage foldback mode, the power receiving device control circuit 30 may require the target rectifier output voltage not to drop below a predetermined minimum foldback rectifier output voltage level, thereby ensuring that rectifier 50 produces at least the minimum rectifier output power.

[0056] The target rectifier output voltage foldback mode control loop algorithm is implemented in the power receiving device 24. During wireless power transmission, the power transmitting device 12 can convey information indicating the inverter input voltage state to the power receiving device 24. For example, the information could be a message indicating that the inverter input voltage is at the maximum inverter input voltage level. Alternatively, the information could identify the inverter input voltage value. Communication can be performed in a packet carrying the inverter input voltage information. In another example, the information could be a bit flag in an existing data packet to indicate whether the inverter input voltage has reached its maximum level. Communication from the power transmitter 12 to the power receiver 24 can be performed using Frequency Shift Keying (FSK) technology as discussed above. Alternatively, other types of in-band or out-of-band communication can be used if desired.

[0057] In another example, power receiving device 24 may query power transmitting device 12 for information indicating the operating conditions of the inverter of the power transmitting device, wherein the wireless power transmission coil 48 is receiving a wireless power signal transmitted by the wireless power transmitting device 12 using the inverter. Additionally, the information may include a state indicating whether the inverter of the wireless power transmitting device 12 is operating at its maximum input voltage. If the power transmitting device 12 responds to the power receiving device 24's indication that the inverter input voltage is at its maximum level, then, as discussed above, the power receiving device 24 may trigger a target rectifier output voltage foldback mode to adaptively adjust the target rectifier output voltage when the inverter input voltage is at its maximum level.

[0058] Figure 7 Is using Figure 5 and Figure 6The flowchart illustrates an exemplary control loop algorithm implemented in the power receiving device 24 of a wireless power transmission system using feedback control schemes 500 and 600. First, it will be combined with… Figure 5 The exemplary operation of the feedback control scheme 500 shown in the figure is used to illustrate this. Figure 7 flow chart.

[0059] In the wireless power system 8, the wireless power receiving device 24 is the main communication device and controls the power transmission in the wireless power system 8. The receiving device 24 is configured to receive electromagnetic signals 44 from the wireless power transmitting device 12. Before and during power transmission, the receiving device 24 and the transmitting device 12 can negotiate a maximum permissible power level. The power receiving device 24 includes a wireless power transmission coil 48. Additionally, the receiving device 24 includes a rectifier circuit 50 coupled to the wireless power transmission coil 48 and configured to rectify the signal from the wireless power transmission coil into an output voltage. The receiving device 24 also includes a control circuit 30 configured to adjust the rectifier output voltage (e.g., at a target output voltage level) at which the rectifier output voltage is adjusted. Figure 5 The 530A receives a status message indicating the inverter input voltage from the transmitting device 12 and adjusts the target rectifier output voltage based on the status of the inverter input voltage.

[0060] refer to Figure 7 In step 704, the receiving device 24 controls the circuit 30 to measure the current rectifier output voltage value (e.g., using circuit 43) and determine whether it is greater than or equal to the target rectifier output voltage level. If so, in step 706, the receiving device can ramp up the load power until the maximum allowable power is reached, and proceed to step 708. If the current rectifier output voltage value is less than the target rectifier output voltage level, the receiving device proceeds directly to step 708.

[0061] At step 708, the receiving device 24 control circuit 30 determines whether the inverter input voltage is at its maximum level, such as along... Figure 5 The operating conditions of the inverter input voltage profile 520B are described. For example, control circuit 30 may make this determination based on a status message indicating the inverter input voltage received from transmitting device 12. In another example, power receiving device 24 may query power transmitting device 12 for information indicating the state of the inverter input voltage. In either example, if the status indicates that the inverter input voltage is not at its maximum level (e.g., along the curve), then the inverter input voltage is considered to be operating under certain conditions. Figure 5 If the first part of the inverter input voltage curve (520A operating conditions) is obtained, then the receiving device 24 proceeds to step 710.

[0062] At step 710, control circuit 30 adjusts the rectifier output voltage at the target rectifier output voltage level. At step 712, control circuit 30 calculates a control error packet (CEP) so that the power transmitting device can adjust the rectifier output voltage by providing feedback information from the power transmitting device. At step 730, receiving device 24 transmits the CEP to transmitting device 12. Transmitting device 12 can use the information in the CEP to adjust the inverter input voltage.

[0063] Referring to step 708, if the receiving device 24 control circuit 30 determines that the inverter input voltage status message indicates that the inverter input voltage is at its maximum level (e.g., along...), Figure 5 If the operating conditions of the second part 520B of the inverter input voltage curve are met, the receiving device enters the target rectifier output voltage foldback mode (e.g., operating conditions along the second part 530B of the rectifier output voltage curve). At step 720, the receiving device 24 control circuit 30 measures the current rectifier output voltage value (e.g., using circuit 43). When in foldback mode, the current rectifier output voltage value may be lower than the target rectifier output voltage level. Therefore, the receiving device 24 sets the new target rectifier output voltage level to the current rectifier output voltage value and adjusts the rectifier output voltage at the new target rectifier output voltage level. At step 722, the receiving device 24 does not calculate the Control Error Packet (CEP); instead, the receiving device 24 assigns the CEP to the power transmitting device 12 to request more power. The CEP request for more power prompts the transmitting device 12 to increase the inverter input voltage, thereby ensuring that the inverter input voltage remains at the maximum level of the inverter input voltage. At step 730, the receiving device 24 transmits the CEP to the transmitting device 12.

[0064] When the inverter input voltage is at its maximum level, the receiving device 24 will continue to operate in the target rectifier output voltage foldback mode (i.e., Figure 7In steps 720 and 722), and allows the rectifier output voltage to drop. The foldback mode enables the receiving device 24 to adaptively adjust the target rectifier output voltage level to a new target rectifier output voltage level when the load changes (e.g., operating conditions along the second part 530B of the rectifier output voltage curve). When in foldback mode, the receiving device 24 control circuit 30 may require the target rectifier output voltage level not to drop below the minimum foldback voltage level. The receiving device 24 control circuit 30 can compare the current rectifier output voltage value measured at step 720 with the minimum foldback voltage level. If the control circuit 30 determines that the current rectifier output voltage value is less than the minimum foldback voltage level, the control circuit 30 can set the new target rectifier output voltage level to the minimum foldback voltage level and adjust the rectifier output voltage at the new target rectifier output voltage level. By controlling the minimum rectifier output voltage level, the receiving device 24 can ensure that the rectifier 50 produces minimum output power.

[0065] At step 704, when the receiving device 24 control circuit 30 determines that the current rectifier output voltage value is greater than or equal to the target rectifier output voltage level (e.g., along...), the receiving device 24 control circuit 30 determines that the current rectifier output voltage value is greater than or equal to the target rectifier output voltage level (e.g., along...). Figure 5 When the rectifier output voltage curve (part 530A) in the second part of the circuit is in operation, the receiving device 24 will stop operating in foldback mode. Consequently, the inverter input voltage of the transmitting device 12 will not be at its maximum level; instead, it will be at the level along the foldback. Figure 5 The first part of the inverter input voltage curve, 520A, describes the operating conditions. At step 708, the receiving device 24 will proceed to... Figure 7 The control loop on the left side of the flowchart is used to adjust the rectifier output voltage at the target output voltage level and to calculate CEP according to steps 710 and 712.

[0066] Next, we will combine Figure 6 The exemplary operation of the feedback control scheme 600 shown in the figure is used to illustrate this. Figure 7 Flowchart. As noted above, the feedback control scheme 600 improves charging efficiency at light loads and includes a foldback mode control loop for the target rectifier output voltage.

[0067] In the wireless power system 8, the wireless power receiving device 24 is the main communication device and controls the power transmission in the wireless power system 8. The receiving device 24 is configured to receive electromagnetic signals 44 from the wireless power transmitting device 12. Before and during power transmission, the receiving device 24 and the transmitting device 12 can negotiate a maximum permissible power level. The power receiving device 24 includes a wireless power transmission coil 48. Additionally, the receiving device 24 includes a rectifier circuit 50 coupled to the wireless power transmission coil 48 and configured to rectify the signal from the wireless power transmission coil into an output voltage. The receiving device 24 also includes a control circuit 30 configured to measure the characteristics of the rectifier circuit 50 (e.g., using circuit 43). For example, the rectifier circuit characteristics may be rectifier output power and / or rectifier output current.

[0068] The control circuit 30 can determine and dynamically control the target rectifier output voltage level based on a function of the measured characteristics of the rectifier circuit 50. For example, it can be based on... Figure 6 The rectifier output power shown in curve 630 is used to determine and control the target rectifier output voltage. The target rectifier output voltage function (curve 630) can be designed for optimal coupling conditions (i.e., curve portions 630A, 630B, and 630B). 1 This allows the target rectifier output voltage to fold back under poor coupling conditions (i.e., curve portion 630C). The target rectifier output voltage function can provide a lower target rectifier output voltage at light loads (e.g., where lower rectifier output power is required) and a higher target rectifier output voltage at heavy loads (e.g., where higher rectifier output power is required).

[0069] refer to Figure 7 In step 704, the receiving device 24's control circuit 30 measures the current rectifier output power (e.g., using circuit 43) and determines the target rectifier output voltage level based on the measured rectifier output power. The control circuit 30 also measures the current rectifier output voltage value and determines whether it is greater than or equal to the target voltage rectifier output level. If so, in step 706, the receiving device 24 can ramp up the load power until the maximum permissible power is reached, and proceed to step 708. If the current rectifier output voltage value is less than the target rectifier output voltage level, the receiving device proceeds directly to step 708.

[0070] At step 708, the receiving device 24 control circuit 30 determines whether the inverter input voltage is at its maximum level, such as along... Figure 6The operating conditions of the inverter input voltage profile 620C are described. For example, control circuit 30 may make this determination based on a status message indicating the inverter input voltage received from transmitting device 12. In another example, power receiving device 24 may query power transmitting device 12 for information indicating the state of the inverter input voltage. In either example, if the status indicates that the inverter input voltage is not at its maximum level, such as along... Figure 6 If the inverter input voltage curve section 620A or 620B in the circuit meets the operating conditions, then the receiving device 24 proceeds to step 710.

[0071] At step 710, the control circuit 30 determines the target output voltage level (e.g., along the measured rectifier output power) based on the target output voltage level. Figure 6 The rectifier output voltage is adjusted at the operating conditions of the rectifier output voltage section 630A or 630B in the design target rectifier. At step 712, the control circuit 30 calculates a control error packet (CEP) so that the power receiving device can adjust the rectifier output voltage by providing feedback information to the power transmitting device. At step 730, the receiving device 24 transmits the CEP to the transmitting device 12. The transmitting device 12 can use the information in the CEP to adjust the inverter input voltage.

[0072] Referring again to step 708, if the receiving device 24 control circuit 30 determines that the inverter input voltage status message indicates that the inverter input voltage is at its maximum level (e.g., along...), Figure 6 If the operating conditions of the inverter input voltage curve portion 620C are met, the receiving device enters the target rectifier output voltage foldback mode (e.g., operating conditions along the rectifier output voltage curve portion 630C). At step 720, the receiving device 24 control circuit 30 measures the current rectifier output voltage value (e.g., using circuit 43). When in foldback mode, the current rectifier output voltage value may be lower than the target rectifier output voltage level. Therefore, the receiving device 24 sets the new target rectifier output voltage level to the current rectifier output voltage value and adjusts the rectifier output voltage at the new target rectifier output voltage level. At step 722, the receiving device 24 does not calculate the CEP; instead, the receiving device 24 assigns a request for more power from the power transmitting device 12 for the CEP. The CEP request for more power prompts the transmitting device 12 to increase the inverter input voltage, thereby ensuring that the inverter input voltage remains at the maximum inverter input voltage level. At step 730, the receiving device 24 transmits the CEP to the transmitting device 12.

[0073] When the inverter input voltage is at its maximum level, the receiving device 24 will continue to operate in the target rectifier output voltage foldback mode (i.e., Figure 7Steps 720 and 722 in the above steps are followed, and the rectifier output voltage is allowed to drop. The foldback mode allows the receiving device 24 to adaptively adjust the target rectifier output voltage level to a new target rectifier output voltage level when the load changes (e.g., operating conditions along portion 630C of the rectifier output voltage curve). When in foldback mode, the receiving device 24 control circuit 30 may require the target rectifier output voltage level not to drop below the minimum foldback voltage level. The receiving device 24 control circuit 30 can compare the current rectifier output voltage value measured at step 720 with the minimum foldback voltage level. If the control circuit 30 determines that the current rectifier output voltage value is less than the minimum foldback voltage level, the control circuit 30 can set the new target rectifier output voltage level to the minimum foldback voltage level and adjust the rectifier output voltage at the new target rectifier output voltage level. By controlling the minimum rectifier output voltage level, the receiving device 24 can ensure that the rectifier 50 produces the minimum rectifier output power.

[0074] The foregoing description is provided for illustrative purposes and should not be construed as limiting the invention. While the invention has been described with reference to illustrative examples or methods, it should be understood that the terms used herein are descriptive and illustrative, not limiting. Furthermore, although the invention has been described herein with reference to specific structures, methods, and examples, the invention is not intended to be limited to the specific details disclosed herein, as the invention extends to all structures, methods, and uses within the scope of the appended claims. Those skilled in the art who benefit from the teachings of this specification will be able to make numerous modifications to the invention as described herein, and changes can be made without departing from the scope and spirit of the invention as defined by the appended claims.

Claims

1. A wireless power receiving device, the wireless power receiving device being configured to receive a wireless power signal from a wireless power transmitting device, the wireless power receiving device comprising: Wireless power transmission coil; A rectifier circuit coupled to the wireless power transmission coil and configured to rectify a signal from the wireless power transmission coil into a rectifier output voltage; and Control circuit, the control circuit being configured to: Adjust the rectifier output voltage at the target rectifier output voltage level; Receive a status message from the wireless power transmitting device indicating the inverter input voltage of the wireless power transmitting device; The status message received from the wireless power transmitting device is used to determine whether the inverter input voltage is at the maximum inverter input voltage level; as well as The control circuit adjusts the target rectifier output voltage level based on the status message indicating the inverter input voltage, wherein if it is determined that the inverter input voltage is at the maximum inverter input voltage level, the control circuit: Measure the current rectifier output voltage value; as well as The current rectifier output voltage value is compared with the minimum foldback voltage level. If it is determined that the current rectifier output voltage value is less than or equal to the minimum foldback voltage level, the control circuit sets the new target rectifier output voltage level to the minimum foldback voltage level. as well as Adjust the rectifier output voltage at the new target rectifier output voltage level.

2. The wireless power receiving device according to claim 1, wherein if it is determined that the current rectifier output voltage value is greater than the minimum foldback voltage level, the control circuit: Set the new target rectifier output voltage level to the current rectifier output voltage value; and Adjust the rectifier output voltage at the new target rectifier output voltage level.

3. The wireless power receiving device according to claim 1, wherein if it is determined that the current rectifier output voltage value is greater than the minimum foldback voltage level, the control circuit compares the current rectifier output voltage value with the target rectifier output voltage level.

4. The wireless power receiving device according to claim 3, wherein if it is determined that the current rectifier output voltage value is less than the target rectifier output voltage level, the control circuit will control the transmission of an error packet (CEP) to the wireless power transmitting device to request more power.

5. The wireless power receiving device according to claim 1, wherein the control circuit determines, based on the status message, that the inverter input voltage is not at the maximum inverter input voltage level, the control circuit: Adjust the rectifier output voltage at the target rectifier output voltage level.

6. A wireless power receiving device, the wireless power receiving device being configured to receive a wireless power signal from a wireless power transmitting device, the wireless power receiving device comprising: Wireless power transmission coil; A rectifier circuit coupled to the wireless power transmission coil and configured to rectify a signal from the wireless power transmission coil into a rectifier output voltage; and Control circuit, the control circuit being configured to: Receive a status message from the wireless power transmitting device indicating the inverter input voltage of the wireless power transmitting device; The status message received from the wireless power transmitting device is used to determine whether the inverter input voltage is at the maximum inverter input voltage level. If it is determined that the inverter input voltage is not at the maximum inverter input voltage level, the control circuit: Measure the characteristics of the rectifier circuit; The target rectifier output voltage level is determined based on the measured characteristics of the rectifier circuit. as well as The output voltage of the rectifier is dynamically adjusted at the target rectifier output voltage level; If it is determined that the inverter input voltage is at the maximum inverter input voltage level, the control circuit: Measure the current rectifier output voltage value; The current rectifier output voltage value is compared with the minimum foldback voltage level. If it is determined that the current rectifier output voltage value is less than or equal to the minimum foldback voltage level, the control circuit sets the new target rectifier output voltage level to the minimum foldback voltage level. as well as Adjust the rectifier output voltage at the new target rectifier output voltage level.

7. The wireless power receiving device according to claim 6, wherein the characteristic of the rectifier circuit includes one of rectifier output power and rectifier output current.

8. The wireless power receiving device according to claim 6, wherein if it is determined that the current rectifier output voltage value is greater than the minimum foldback voltage level, the control circuit: Set the new target rectifier output voltage level to the current rectifier output voltage value; and Adjust the rectifier output voltage at the new target rectifier output voltage level.

9. The wireless power receiving device according to claim 6, wherein if it is determined that the current rectifier output voltage value is greater than the minimum foldback voltage level, the control circuit: Measure the characteristics of the rectifier circuit; The target rectifier output voltage level is determined based on the measured characteristics of the rectifier circuit; and The current rectifier output voltage value is compared with the target rectifier output voltage level.

10. The wireless power receiving device of claim 9, wherein the control circuit determines that the current rectifier output voltage value is less than the target rectifier output voltage level, and the control circuit controls the transmission of a control error packet (CEP) to the wireless power transmitting device to request more power.

11. A wireless power receiving device, the wireless power receiving device being configured to receive a wireless power signal from a wireless power transmitting device, the wireless power receiving device comprising: Wireless power transmission coil; A rectifier circuit coupled to the wireless power transmission coil and configured to rectify a signal from the wireless power transmission coil into a rectifier output voltage; and Control circuit, the control circuit being configured to: The wireless power transmitting device is requested to provide information indicating the operating conditions of the inverter of the wireless power transmitting device, wherein the wireless power transmission coil is receiving a wireless power signal transmitted by the wireless power transmitting device using the inverter; The information includes a status message indicating whether the inverter of the wireless power transmitting device is operating at the maximum inverter input voltage level; If it is determined that the inverter input voltage of the inverter is not at the maximum inverter input voltage level, the control circuit: Adjust the rectifier output voltage at the target rectifier output voltage level. If it is determined that the inverter input voltage is at the maximum inverter input voltage level, the control circuit: Measure the current rectifier output voltage value; The current rectifier output voltage value is compared with the minimum foldback voltage level. If it is determined that the current rectifier output voltage value is less than or equal to the minimum foldback voltage level, the control circuit sets the new target rectifier output voltage level to the minimum foldback voltage level. as well as Adjust the rectifier output voltage at the new target rectifier output voltage level.

12. The wireless power receiving device of claim 11, wherein if it is determined that the current rectifier output voltage value is greater than the minimum foldback voltage level, the control circuit: Set the new target rectifier output voltage level to the current rectifier output voltage value; and Adjust the rectifier output voltage at the new target rectifier output voltage level.

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