PATENT DOCUMENT

Publication Number: US-10923959-B2
Application Number: US-201916505370-A
Country: US
Kind Code: B2

Title: Wireless power system with reconfigurable rectifier circuitry

Abstract:
A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device may be a wireless charging mat or other device with coils for transmitting wireless power signals. The wireless power receiving device may be a cellular telephone or other device with coils for receiving the transmitted wireless power signals. The wireless power receiving device has adjustable rectifier circuitry coupled to a pair of coils. The pair of coils is coupled in series at a node. A transistor is coupled between ground and the node and is controlled by control circuitry. The state of the transistor can be changed to place the adjustable rectifier circuitry in either a first mode of operation in which the adjustable rectifier circuitry forms a full-bridge rectifier or a second mode of operation in which the adjustable rectifier circuitry forms a pair of parallel half-bridge rectifiers.

Claims:
What is claimed is: 
     
       1. A wireless power receiving device configured to wirelessly receive power during wireless power transmission from a wireless power transmitting device, comprising:
 first and second coils coupled in series and configured to receive wireless power signals; and 
 adjustable rectifier circuitry that is coupled to the first and second coils and that is configured to produce direct-current output power from the received wireless power signals, wherein the adjustable rectifier circuitry is configured to:
 operate in a first mode in which the adjustable rectifier circuitry forms a full-bridge rectifier; and 
 operate in a second mode in which the adjustable rectifier circuitry forms a pair of parallel half-bridge rectifiers. 
 
 
     
     
       2. The wireless power receiving device of  claim 1  wherein the first and second coils are connected to each other at a node, wherein the adjustable rectifier circuitry further comprises:
 an array of four diodes; 
 capacitors coupled between the array of four diodes and the first and second coils; and 
 a transistor coupled to the node. 
 
     
     
       3. The wireless power receiving device of  claim 2  further comprising control circuitry configured to control the transistor to adjust the adjustable rectifier circuitry. 
     
     
       4. The wireless power receiving device of  claim 3  wherein the control circuitry is configured to turn the transistor on and off to switch the adjustable rectifier circuitry between the first and second modes. 
     
     
       5. The wireless power receiving device of  claim 4  wherein the transistor has a first source-drain terminal coupled to the node and a second source-drain terminal coupled to ground. 
     
     
       6. The wireless power receiving device of  claim 4  further comprising:
 a display; and 
 a housing to which the display is mounted. 
 
     
     
       7. The wireless power receiving device of  claim 6  wherein the first and second coils are in the housing and overlapped by the display. 
     
     
       8. The wireless power receiving device of  claim 7  wherein in the first mode the adjustable rectifier circuitry is configured to use the first coil to receive a magnetic field and to use the second coil to receive a magnetic field that is in phase with the magnetic field received by the first coil. 
     
     
       9. The wireless power receiving device of  claim 8  wherein in the second mode the adjustable rectifier circuitry is configured to use the first coil to receive a magnetic field that is out of phase with a magnetic field received by the second coil. 
     
     
       10. The wireless power receiving device of  claim 1  wherein in the first mode the adjustable rectifier circuitry is configured to pass current in series through the first and second coils. 
     
     
       11. An electronic device comprising:
 a housing; 
 a display mounted to the housing; 
 first and second coils in the housing that are configured to receive wireless power signals through; 
 adjustable rectifier circuitry coupled to the first and second coils; and 
 control circuitry configured to adjust the adjustable rectifier circuitry between:
 a first configuration in which alternating-current signals are received by the adjustable rectifier circuitry from the first coil that are in phase with alternating-current signals received by the adjustable rectifier circuitry from the second coil; and 
 a second configuration in which alternating-current signals are received by the adjustable rectifier circuitry from the first coil that are out of phase with alternating-current signals received by the adjustable rectifier circuitry from the second coil. 
 
 
     
     
       12. The electronic device of  claim 11  wherein the alternating-current signals received by the adjustable rectifier circuitry from the first coil are 180° out of phase with the alternating-current signals received by the adjustable rectifier circuitry from second coil during operation in the second configuration. 
     
     
       13. The electronic device of  claim 11  wherein the first and second coils are coupled at a node and wherein the adjustable rectifier circuitry comprises a switch coupled to the node. 
     
     
       14. The electronic device of  claim 13  wherein the control circuitry is configured to adjust the adjustable rectifier circuitry by controlling the switch to operate in a selected one of:
 1) a first state in which the adjustable rectifier circuitry forms a full-bridge rectifier; and 
 2) a second state that is different than the first state in which the adjustable rectifier circuitry forms two parallel half-bridge rectifiers. 
 
     
     
       15. The electronic device of  claim 13  wherein the switch has a first state when the adjustable rectifier circuitry is in the first configuration and wherein the switch has a second state that is different than the first state when the adjustable rectifier circuitry is in the second configuration. 
     
     
       16. The electronic device of  claim 11  wherein the housing comprises a cellular telephone housing. 
     
     
       17. An electronic device comprising:
 first and second coils that are configured to receive wireless power signals; 
 adjustable rectifier circuitry coupled to the first and second coils that is adjustable to operable in:
 1) a first mode in which the adjustable rectifier circuitry forms a full-bridge rectifier; and 
 2) a second mode in which the adjustable rectifier circuitry forms two parallel half-bridge rectifiers. 
 
 
     
     
       18. The electronic device of  claim 17  wherein the adjustable rectifier circuitry comprises a transistor, the electronic device further comprising:
 control circuitry configured to control the transistor to adjust the adjustable rectifier circuitry between the first and second modes. 
 
     
     
       19. The electronic device of  claim 18  wherein the first and second coils are connected in series at a node and wherein the transistor is coupled to the node. 
     
     
       20. The electronic device of  claim 19  further comprising a display.

Description:
This application claims benefit of provisional patent application No. 62/828,933, filed Apr. 3, 2019, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to power systems, and, more particularly, to wireless power systems for charging electronic devices. 
     BACKGROUND 
     In a wireless charging system, a wireless power transmitting device such as a charging mat wirelessly transmits power to a wireless power receiving device such as a portable electronic device. The portable electronic device has a coil and rectifier circuitry. The coil of the portable electronic device receives alternating-current wireless power signals from the wireless charging mat. The rectifier circuitry converts the received signals into direct-current power. 
     SUMMARY 
     A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device is a wireless charging mat or other device with coils for transmitting wireless power signals. The wireless power receiving device is a cellular telephone or other device with coils for receiving the transmitted wireless power signals. 
     To enhance wireless power transmission efficiency in a variety of operating scenarios, the wireless power receiving device may configure the coils in the wireless power receiving device to receive magnetic flux that is transmitted from the wireless power transmitting device in a first orientation (e.g., horizontal flux) or a second orientation (e.g., vertical flux). 
     The wireless power receiving device has adjustable rectifier circuitry coupled to a pair of coils. When receiving wireless power, a first of the coils can produce alternating-current signals that are in phase or that are out of phase (e.g., 180° out of phase) with respect to a second of the coils depending on the orientation of the transmitted magnetic flux. The adjustable rectifier circuitry is dynamically reconfigured to accommodate these different scenarios. 
     The first and second coils are coupled in series at a node. A transistor is coupled between ground and the node. The transistor is controlled by control circuitry. The state of the transistor can be changed to place the adjustable rectifier circuitry in either a first mode of operation in which the adjustable rectifier circuitry forms a full-bridge rectifier or a second mode of operation in which the adjustable rectifier circuitry forms a pair of parallel half-bridge rectifiers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative wireless charging system that includes a wireless power transmitting device and a wireless power receiving device in accordance with an embodiment. 
         FIG. 2  is a circuit diagram of wireless power transmitting and receiving circuitry in accordance with an embodiment. 
         FIG. 3  is a side view of an illustrative wireless power transmitting device such as a wireless charging pad and a corresponding wireless power receiving device such as a cellular telephone with multiple wireless power receiving coils in accordance with an embodiment. 
         FIG. 4  is a circuit diagram of illustrative adjustable rectifier circuitry in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A wireless power system includes a wireless power transmitting device such as a wireless charging mat. The wireless power transmitting device wirelessly transmits power to a wireless power receiving device such as a wristwatch, cellular telephone, tablet computer, laptop computer, or other electronic equipment. The wireless power receiving device uses power from the wireless power transmitting device for powering the device and for charging an internal battery. 
     The wireless power transmitting device communicates with the wireless power receiving device and obtains information on the characteristics of the wireless power receiving device. In some embodiments, the wireless power transmitting device has multiple power transmitting coils. In such embodiments, the wireless power transmitting device uses information from the wireless power receiving device and/or measurements made in the wireless power transmitting device to determine which coil or coils in the transmitting device are magnetically coupled to wireless power receiving devices. Coil selection is then performed in the wireless power transmitting device. 
     Wireless power is transmitted from the wireless power transmitting device to the wireless power receiving device using selected coil(s) to charge a battery in the wireless power receiving device and/or to power other load circuitry. The wireless power receiving device has reconfigurable coils. For example, the wireless power receiving device may have a pair of coils coupled to adjustable rectifier circuitry. The rectifier circuitry can be operated in different modes to enhance wireless power reception by the coils. 
     An illustrative wireless power system (wireless charging system) is shown in  FIG. 1 . As shown in  FIG. 1 , wireless power system  8  includes a wireless power transmitting device such as wireless power transmitting device  12  and includes a wireless power receiving device such as wireless power receiving device  24 . Wireless power transmitting device  12  includes control circuitry  16 . Wireless power receiving device  24  includes control circuitry  30 . Control circuitry in system  8  such as control circuitry  16  and control circuitry  30  is used in controlling the operation of system  8 . This control circuitry may include processing circuitry associated with microprocessors, power management units, baseband processors, digital signal processors, microcontrollers, and/or application-specific integrated circuits with processing circuits. The processing circuitry implements desired control and communications features in devices  12  and  24 . For example, the processing circuitry may be used in selecting coils, determining power transmission levels, processing sensor data and other data, processing user input, handling negotiations between devices  12  and  24 , sending and receiving in-band and out-of-band data, making measurements, and otherwise controlling the operation of system  8 . 
     Control circuitry in system  8  may be configured to perform operations in system  8  using hardware (e.g., dedicated hardware or circuitry), firmware and/or software. Software code for performing operations in system  8  is stored on non-transitory computer readable storage media (e.g., tangible computer readable storage media) in control circuitry  8 . The software code may sometimes be referred to as software, data, program instructions, instructions, or code. The non-transitory computer readable storage media may include non-volatile memory such as non-volatile 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, or the like. Software stored on the non-transitory computer readable storage media may be executed on the processing circuitry of control circuitry  16  and/or  30 . The processing circuitry may include application-specific integrated circuits with processing circuitry, one or more microprocessors, a central processing unit (CPU) or other processing circuitry. 
     Power transmitting device  12  may be a stand-alone power adapter (e.g., a wireless charging mat or charging puck that includes power adapter circuitry), may be a wireless charging mat or puck that is coupled to a power adapter or other equipment by a cable, may be a portable device, may be equipment that has been incorporated into furniture, a vehicle, or other system, may be a removable battery case, or may be other wireless power transfer equipment. Illustrative configurations in which wireless power transmitting device  12  is a wireless charging mat are sometimes described herein as an example. 
     Power receiving device  24  may be a portable electronic device such as a wristwatch, a cellular telephone, a laptop computer, a tablet computer, an accessory such as an earbud, or other electronic equipment. Power transmitting device  12  may be coupled to a wall outlet (e.g., an alternating current power source), may have a battery for supplying power, and/or may have another source of power. Power transmitting device  12  may have an alternating-current (AC) to direct-current (DC) power converter such as AC-DC power converter  14  for converting AC power from a wall outlet or other power source into DC power. DC power may be used to power control circuitry  16 . During operation, a controller in control circuitry  16  uses power transmitting circuitry  52  to transmit wireless power to power receiving circuitry  54  of device  24 . Power transmitting circuitry  52  may have switching circuitry (e.g., inverter circuitry  61  formed from transistors) that is turned on and off based on control signals provided by control circuitry  16  to create AC current signals through one or more wireless power transmitting coils such as wireless power transmitting coils  36 . Coils  36  may be arranged in a planar coil array (e.g., in configurations in which device  12  is a wireless charging mat) or may be arranged to form a cluster of coils (e.g., in configurations in which device  12  is a wireless charging puck). In some arrangements, device  12  may have only a single coil. In other arrangements, a wireless charging device such as a wireless charging mat may have multiple coils (e.g., two or more coils, 5-10 coils, at least 10 coils, 10-30 coils, fewer than 35 coils, fewer than 25 coils, or other suitable number of coils). 
     As the AC currents pass through one or more coils  36 , alternating-current electromagnetic (e.g., magnetic) fields (wireless power signals  44 ) are produced that are received by one or more corresponding receiver coils such as coil(s)  48  in power receiving device  24 . Device  24  may have a single coil  48 , at least two coils  48 , at least three coils  48 , at least four coils  48 , or other suitable number of coils  48 . In an illustrative configuration, which may sometimes be described herein as an example, device  24  has a pair of coils  48 . When the alternating-current electromagnetic fields are received by coils  48 , corresponding alternating-current currents are induced in coils  48 . Rectifier circuitry such as rectifier circuitry  50 , which contains rectifying components such as synchronous rectification metal-oxide-semiconductor transistors arranged in a bridge network, converts received AC signals (received alternating-current signals associated with electromagnetic signals  44 ) from one or more coils  48  into DC voltage signals for powering device  24 . 
     The DC voltage produced by rectifier circuitry  50  (sometime referred to as rectifier output voltage Vrect) can be used in charging a battery such as battery  58  and can be used in powering other components in device  24 . For example, device  24  may include input-output devices  56  such as a display, touch sensor, communications circuits, audio components, sensors, light-emitting diode status indicators, other light-emitting and light detecting components, and other components and these components (which form a load for device  24 ) may be powered by the DC voltages produced by rectifier circuitry  50  (and/or DC voltages produced by battery  58 ). 
     Device  12  and/or device  24  may communicate wirelessly using in-band or out-of-band communications. Device  12  may, for example, have wireless transceiver circuitry  40  that wirelessly transmits out-of-band signals to device  24  using an antenna. Wireless transceiver circuitry  40  may be used to wirelessly receive out-of-band signals from device  24  using the antenna. Device  24  may have wireless transceiver circuitry  46  that transmits out-of-band signals to device  12 . Receiver circuitry in wireless transceiver  46  may use an antenna to receive out-of-band signals from device  12 . In-band transmissions between devices  12  and  24  may be performed using coils  36  and  48 . With one illustrative configuration, frequency-shift keying (FSK) is used to convey in-band data from device  12  to device  24  and amplitude-shift keying (ASK) is used to convey in-band data from device  24  to device  12 . Power may be conveyed wirelessly from device  12  to device  24  during these FSK and ASK transmissions. 
     It is desirable for power transmitting device  12  and power receiving device  24  to be able to communicate information such as received power, states of charge, and so forth, to control wireless power transfer. However, the above-described technology need not involve the transmission of personally identifiable information in order to function. Out of an abundance of caution, it is noted that to the extent that any implementation of this charging technology involves the use of personally identifiable information, implementers should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     Control circuitry  16  has external object measurement circuitry  41  that may be used to detect external objects on the charging surface of device  12  (e.g., on the top of a charging mat or, if desired, to detect objects adjacent to the coupling surface of a charging puck). Circuitry  41  can detect foreign objects such as coils, paper clips, and other metallic objects and can detect the presence of wireless power receiving devices  24  (e.g., circuitry  41  can detect the presence of one or more coils  48 ). During object detection and characterization operations, external object measurement circuitry  41  can be used to make measurements on coils  36  to determine whether any devices  24  are present on device  12 . 
     In an illustrative arrangement, measurement circuitry  41  of control circuitry  16  contains signal generator circuitry (e.g., oscillator circuitry for generating AC probe signals at one or more probe frequencies, a pulse generator that can create impulses so that impulse responses can be measured to gather inductance information, Q-factor information, etc.) and signal detection circuitry (e.g., filters, analog-to-digital converters, impulse response measurement circuits, etc.). During measurement operations, switching circuitry in device  12  may be adjusted by control circuitry  16  to switch each of coils  36  into use. As each coil  36  is selectively switched into use, control circuitry  16  uses the signal generator circuitry of signal measurement circuitry  41  to apply a probe signal to that coil while using the signal detection circuitry of signal measurement circuitry  41  to measure a corresponding response. Measurement circuitry  43  in control circuitry  30  and/or in control circuitry  16  may also be used in making current and voltage measurements. Based on this information or other information, control circuitry  30  can configure rectifier circuitry  50  to help enhance wireless power reception by coils  48 . For example, rectifier circuitry  50  can be configured to operate in a vertical field mode in scenarios in which transmitted magnetic fields from device  12  are predominantly vertical (e.g., when the coils  36  that are overlapped by coils  48  are driven in phase) and can be configured to operate in a horizontal field mode in scenarios in which transmitted magnetic fields from device  12  are predominantly horizontal (e.g., when the coils  36  that are overlapped by coils  48  are driven out of phase). 
       FIG. 2  is a circuit diagram of illustrative wireless charging circuitry for system  8 . As shown in  FIG. 2 , circuitry  52  may include inverter circuitry such as one or more inverters  61  or other drive circuitry that produces wireless power signals that are transmitted through an output circuit that includes one or more coils  36  and capacitors such as capacitor  70 . In some embodiments, device  12  may include multiple individually controlled inverters  61 , each of which supplies drive signals to a respective coil  36 . In other embodiments, an inverter  61  is shared between multiple coils  36  using switching circuitry. 
     During operation, control signals for inverter(s)  61  are provided by control circuitry  16  at control input  74 . A single inverter  61  and single coil  36  is shown in the example of  FIG. 2 , but multiple inverters  61  and multiple coils  36  may be used, if desired. In a multiple coil configuration, switching circuitry can be used to couple a single inverter  61  to multiple coils  36  and/or each coil  36  may be coupled to a respective inverter  61 . During wireless power transmission operations, transistors in one or more selected inverters  61  are driven by AC control signals from control circuitry  16 . This causes the output circuit formed from selected coil  36  and capacitor  70  to produce alternating-current electromagnetic fields (signals  44 ) that are received by wireless power receiving circuitry  54  using a wireless power receiving circuit formed from one or more coils  48  and one or more capacitors  72  in device  24 . If desired, the relative phase between driven coils  36  (e.g., the phase of one of coils  36  that is being driven relative to another adjacent one of coils  36  that is being driven) may be adjusted by control circuitry  16  to help enhance wireless power transfer between device  12  and device  24 . Rectifier circuitry  50  is coupled to one or more coils  48  (e.g., a pair of coils) and converts received power from AC to DC and supplies a corresponding direct current output voltage Vrect across rectifier output terminals  76  for powering load circuitry in device  24  (e.g., for charging battery  58 , for powering a display and/or other input-output devices  56 , and/or for powering other components). A single coil  48  or multiple coils  48  may be included in device  24 . In an illustrative configuration, device  24  may be a cellular telephone or other portable device with a pair of coils  48 . Other configurations may be used, if desired. 
       FIG. 3  is a cross-sectional side view of system  8  in an illustrative configuration in which wireless power transmitting device  12  is a wireless charging mat and in which wireless power receiving device  24  is a cellular telephone (as an example). Device  12  has housing  90  (e.g., a mat housing formed form polymer, other dielectric material, and/or other materials). Cable  92  may be coupled to housing  90  and may provide power to device  12 . In some configurations, power may be provided by an internal battery. 
     Device  24  may have a housing such as housing  96 . Housing  96  and device  24  may have opposing front and rear faces such as front face F and rear face R. Display  99  may be formed on front face F of housing  96  and device  24  and may lie in a plane that is perpendicular to the Z axis (e.g., a plane such as the X-Y plane of  FIG. 3  that is parallel to the planes including front face F and rear face R of housing  96 ). 
     The coils in devices  12  and/or  24  may have any suitable number of turns of wire. In some configurations, the coils may be formed from turns of wire wrapped around cores made of iron, ferrite, or other magnetic material. 
     During wireless power transmission, device  12  may use one or more coils  36  to transmit wireless power signals. For example, coils  48  of device  24  may overlap a pair of coils in device  12  such as coils  36 ′″ and  36 ″″. Coils  36 ′″ and  36 ″″ may be coupled to respective inverters  61 . During operation, control circuitry  16  may direct these respective inverters to drive corresponding coils  36 ′″ and  36 ″″ in phase (e.g., to produce respective in-phase magnetic fields B 1  and B 2 ). The magnetic field produced by device  12  in this type of arrangement may predominantly extend vertically through coils  48  parallel to the vertical Z axis of  FIG. 3 . Accordingly, operation of device  12  in a configuration in which coils  36 ′″ and  36 ″″ are driven in phase may sometimes be referred to as operation of device  12  in a vertical field mode. In other arrangements, control circuitry  16  may use the inverters  61  that are coupled to coils  36 ′″ and  36 ″″ to drive coils  36 ′″ and  36 ″″ out of phase. The inverter circuitry of device  12  may, as an example, drive coils  36 ′″ and  36 ″″ 180° out of phase (e.g., to produce respective of-of-phase magnetic fields B 1  and B 2 ′). This creates horizontal magnetic fields (e.g., magnetic field lines that extends parallel to the X-Y plane of  FIG. 3  and parallel to the charging surface of device  12 ). Operation of device  12  in this configuration may sometimes be referred to as a horizontal field mode. Some wireless power receiving devices such as illustrative wireless power receiving device  24 ′ may have coil(s)  48  oriented to receive horizontal magnetic fields, (e.g., horizontal field BH produced by driving coils  36 ′ and  36 ″ 180° out of phase with respect to each other). 
     As these examples demonstrate, the coils  36  that are selected for use in device  12  and the relative phase of the drive currents that are applied to the selected coils  36  during operation affect the location and orientation of the magnetic fields produce by coils  36 . The location and orientation of the magnetic fields produced by coils  36  and the location and orientation of coils  48  relative to these fields can affect wireless power transmission efficiency. With an illustrative arrangement, which is sometimes described herein as an example, device  24  has a pair of coils  48  coupled to adjustable rectifier circuitry  50 . In this arrangement, rectifier circuitry  50  may convert received wireless power from a pair of coils (first and second coils  48 ) to direct-current power. 
     Rectifier circuitry  50  is adjusted dynamically by control circuitry  16  to help enhance wireless power reception. As an example, control circuitry  16  can configure rectifier circuitry  50  for operation in a vertical field mode appropriate for enhancing wireless power reception from vertical magnetic fields or a horizontal field mode appropriate for enhancing wireless power reception from horizontal magnetic fields. In the vertical field mode, the magnetic fields B 1  and B 2  received by the first and second coils  48  are generally in phase and rectifier circuitry  50  is configured to convert these in-phase wireless power signals to direct-current power. In the horizontal field mode, the magnetic fields B 1  and B 2 ′ received by the first and second coils are out-of-phase with respect to each other (e.g., 180° out of phase) and rectifier circuitry  50  is reconfigured to efficiently convert these wireless power signals to direct-current power. 
       FIG. 4  is a circuit diagram of illustrative adjustable circuitry that may be used in forming adjustable rectifier  50  for wireless power receiving device  24 . As shown in  FIG. 4 , wireless power may be received at a pair of coils  48  in device  24  such as first coil C 1  and second C 2 . Coils C 1  and C 2  may, as an example, be mounted in housing  96  of device  24  as shown in  FIG. 3 . Coils C 1  and C 2  may have wire turns that are wound in the same sense (e.g., both clockwise or both counterclockwise) or may, as shown in  FIG. 4  have opposite winding senses (e.g., coil C 1  may be wound clockwise (CW) while coil C 2  is wound counterclockwise (CCW)). Capacitors  72  may be interposed between coils  48  and nodes N 3  and N 5 , which serve as inputs (input terminals) for adjustable rectifier circuitry  50 . During operation of rectifier circuitry  50 , direct-current output voltage Vrect is produced across output terminals  76  to power load  100  (e.g., to power input-output devices  56 , to charge battery  58 , and to supply power to other circuitry in power receiving device  24 ). Capacitor  102  may be coupled across terminals  76  in parallel with load  100  to help reduce voltage ripple. 
     Coils C 1  and C 2  may be coupled in series between nodes N 2  and N 4 . Coil C 1  may have a first terminal coupled to node N 2  and a second terminal coupled to node N 1 . Coil C 2  may have a first terminal coupled to node N 4  and a second terminal coupled to the second terminal of coil C 1  at node N 1 . Rectifier circuitry  50  may have an array of four rectifier transistors T 1 , T 2 , T 3 , and T 4 . Transistors T 1 , T 2 , T 3 , and T 4  may be passively driven field-effect transistors having body diodes coupled between the source-drain terminals of the transistors (e.g., transistors T 1 , T 2 , T 3 , and T 4  may form an array of four respective diodes). If desired, transistors T 1 , T 2 , T 3 , and T 4  may be actively driven to perform active rectification. Passively driven schemes are described herein as an example. 
     Each of transistors T 1 , T 2 , T 3 , and T 4  has a body diode having terminals coupled to the source-drain terminals of the transistor. Transistor T 1  may have body diode D 1  coupled in parallel with transistor switch SW 1 , which is open. Transistor T 2  may have body diode D 2  coupled in parallel with transistor switch SW 2 , which is open. Transistors T 3  and T 4  may respectively have body diodes D 3  and D 4  coupled respectively in parallel with transistor switches SW 3  and SW 4 , which are open. In a passively driven scheme, transistors T 1 , T 2 , T 3 , and T 4  form an array of four respective diodes D 1 , D 2 , D 3 , and D 4  that are used for rectification. 
     Adjustable rectifier circuitry  50  has transistor T 5 . Transistor T 5  may include a body diode D 5  coupled in parallel with transistor switch SW 5 , which may be controlled by a control signal received at the gate of transistor T 5  from control circuitry  30 . The source-drain terminals of transistor T 5  may be coupled, respectively to node N 1  and ground  104 . Control circuitry  30  can selectively place rectifier circuitry  50  in a first mode (sometimes referred to as the vertical field mode or vertical mode) in which transistor switch SW 5  of transistor T 5  is closed) and a second mode (sometimes referred to as the horizontal field mode or horizontal mode) in which transistor switch SW 5  of transistor T 5  is open). 
     In the vertical mode, switch SW 5  is closed and forms a short circuit between node N 1  and ground  104  and diodes D 1 , D 2 , D 3 , and D 4  (e.g., transistors T 1 , T 2 , T 3 , and T 4 ) of adjustable rectifier circuitry  50  form two half-bridge rectifiers that are used in parallel. A first half-bridge rectifier is formed from transistors T 1  and T 2  (diodes D 1  and D 2 ) and a second half-bridge rectifier is formed from transistors T 3  and T 4  (diodes D 3  and D 4 ). During operation in the vertical mode, current IVP flows from coils  48  through circuitry  50  during positive cycles of the received AC wireless power signal, thereby powering load  100 . During negative cycles of the received AC wireless power signal in the vertical mode, current IVN flows and charges capacitors  72 . 
     In the horizontal mode, transistor T 5  has a different state (e.g., switch SW 5  is open). When switch SW 5  is open, diode D 5  is switched into use between node N 1  and ground  104 . In this mode, transistors T 1 , T 2 , T 3 , and T 4  (diodes D 1 , D 2 , D 3 , and D 4 ) of adjustable rectifier circuitry  50  form a full bridge rectifier. During positive cycles, current IHP flows through rectifier circuitry  50  and powers load  100 . During negative cycles, current IHN flows through rectifier circuitry  50  and powers load  100 . 
     Accordingly, adjustable rectifier circuitry  50  can be used to receive vertical mode magnetic fields (e.g., coil C 1  may receive field B 1  of  FIG. 3  and coil C 2  may receive field B 2  of  FIG. 3 ) and, when reconfigured by opening switch SW 5 , can be used to receive horizontal mode magnetic fields (e.g., coil C 1  may receive field B 1  of  FIG. 3  and coil C 2  may receive field B 2 ′ of  FIG. 3 ). By allowing control circuitry  30  to control the state of rectifier circuitry  50  (e.g., by controlling the state of switching circuitry such as switch SW 5  of transistor T 5 ), control circuitry  30  can adjust coils  48  and rectifier circuitry  50  to handle vertical magnetic fields or horizontal magnetic fields. This allows circuitry  50  to be dynamically adjusted to accommodate changes in the magnetic field received by device  24  due to changes in the wireless power signal transmitted by device  12  and/or placement and orientation changes of devices  12  and  24 . The adjustability of rectifier circuitry  50  therefore provides device  24  with enhanced flexibility to pick up both horizontal and vertical magnetic flux. If desired, the incorporation of coils C 1  and C 2  in device  24  may allow wireless power signals to be transmitted to accessory devices. For example, inverter circuitry in device  24  may be coupled to coils C 1  and C 2  and can drive these coils to produce out-of-phase magnetic fields (e.g., horizontal magnetic fields) that can be received by wireless earbuds or other power receiving devices that overlap coils  48 . 
     Satisfactory wireless power transfer may be obtained by ensuring satisfactory tuning of the wireless power transfer circuitry in system  8 . The total inductance for coils  48  coupled in series is 2L, where L is the inductance of coil C 1  and L is the inductance of coil C 2 . The effective capacitance of capacitors  72  in series is C/2, where C is the capacitance of each capacitor  72 . The resonant frequency ffb for full bridge operation (used in horizontal mode) is thus given by equation 1.
 
 ffb= 1/[2π(2 L*C/ 2) 1/2 ]  (1)
 
     This is the same as the resonant frequency fhb for half bridge operation (used in vertical mode) that is given by equation 2.
 
 fhb= 1/[2π( L*C ) 1/2 ]  (2)
 
     Because ffb and fhb are the same, the tuning of rectifier circuitry  50  does not vary even as control circuitry  30  switches rectifier circuitry  50  between vertical and horizontal modes, thereby helping to ensure that the wireless power receiving circuitry of device  24  will not become detuned when switching between modes. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20190708
Publication Date: 20210216
Grant Date: 20210216
Priority Date: 20190403
Inventors: REN, SAINING
LEUNG, HO FAI
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J50/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/402", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/60", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/402", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/60", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B5/0037", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J5/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/26", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 72661935