PATENT DOCUMENT

Publication Number: US-11251656-B2
Application Number: US-201916503394-A
Country: US
Kind Code: B2

Title: Coils for wireless power systems

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 with one or more coils or may be a wireless charging puck with one or more coils. In some embodiments, the wireless charging puck may have six coils or other number of coils arranged in a ring. The wireless power receiving device may have an elongated magnetic core such as a C-shaped core with pillars at opposing ends. First and second coils may be formed on the pillars and a third coil may be formed between the first and second coils. The coils of the wireless power receiving device such as the first and second coils on the magnetic core may be configured to receive magnetic flux emitted by a pair of the six coils in the wireless charging puck.

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:
 a display; 
 electrical components; 
 an elongated magnetic core; 
 first and second coils at opposing first and second ends of the elongated magnetic core, wherein the elongated magnetic core has first and second pillars protruding from the elongated magnetic core at the first and second ends, respectively, and orthogonal to the display; 
 a third coil wrapped around the elongated magnetic core at a location between the first and second coils; and 
 rectifier circuitry that receives wireless power using the first, second, and third coils and that supplies a voltage to the electrical components. 
 
     
     
       2. The wireless power receiving device of  claim 1  wherein the elongated magnetic core is curved along its length. 
     
     
       3. The wireless power receiving device of  claim 2  further comprising:
 a housing in which the elongated magnetic core is mounted 
 the display being disposed on a front face of the housing. 
 
     
     
       4. The wireless power receiving device of  claim 3  wherein the elongated core has a C shape, wherein the first coil comprises wire wrapped around the first pillar, and wherein the second coil comprises wire wrapped around the second pillar. 
     
     
       5. The wireless power receiving device of  claim 4  wherein the first and second coils are coupled in series, wherein the wire wrapped around the first pillar is wrapped clockwise around the first pillar, and wherein the wire wrapped around the second pillar is wrapped counterclockwise around the second pillar. 
     
     
       6. The wireless power receiving device of  claim 3  further comprising:
 a wrist band coupled to the housing. 
 
     
     
       7. The wireless power receiving device of  claim 6 , wherein the first and second pillars extend perpendicular to the display. 
     
     
       8. The wireless power receiving device of  claim 1  further comprising an antenna resonating element configured to transmit wireless signals at frequencies above 1 MHz, wherein the first and second coils are configured to receive wireless power signals at frequencies less than 1 MHz. 
     
     
       9. The wireless power receiving device of  claim 1 , wherein the wireless power receiving device comprises a wristwatch. 
     
     
       10. A wireless power receiving device configured to wirelessly receive power during wireless power transmission from a wireless power transmitting device, comprising:
 a display; 
 an elongated core of magnetic material having opposing first and second ends, wherein the elongated core has a curved shape and lies in a plane, the elongated core has first and second pillars at the first and second ends, respectively, and the first and second pillars extend perpendicular to the plane and the display; 
 first, second, and third coils wrapped around the elongated core, the first and second coils being wrapped around the elongated core at the first and second ends, respectively; and 
 rectifier circuitry that receives wireless power using the first, second, and third coils. 
 
     
     
       11. The wireless power receiving device of  claim 10  further comprising:
 a housing in which the elongated core is mounted, wherein the housing has opposing front and rear faces 
 wherein the display is disposed on the front face, wherein the elongated core has opposing first and second ends, wherein the first coil has wire wrapped around the elongated core at the first end and wherein the second coil has wire wrapped around the elongated core at the second end. 
 
     
     
       12. The wireless power receiving device of  claim 11 , wherein the first coil is on the first pillar and wherein the second coil is on the second pillar. 
     
     
       13. The wireless power receiving device of  claim 12 , wherein the plane in which the elongated core lies is parallel to the front face. 
     
     
       14. The wireless power receiving device of  claim 10  wherein the elongated core is curved along its length. 
     
     
       15. The wireless power receiving device of  claim 14  wherein the elongated core has a C shape. 
     
     
       16. The wireless power receiving device of  claim 10 , wherein the wireless power receiving device comprises a wristwatch. 
     
     
       17. A wireless power receiving device configured to receive wireless power from a wireless charging puck that includes wireless power transmitting circuitry configured to transmit the wireless power using at least one wireless power transmission coil, the wireless power receiving device comprising:
 a wristwatch housing; 
 a display mounted to the wristwatch housing; 
 a magnet in the wristwatch housing that is configured to magnetically hold the puck housing against the wristwatch housing; 
 a wristband coupled to the wristwatch housing; 
 an elongated magnetic core that is bent along its length; and 
 first and second wireless power receiving coils formed from turns of wire at opposing first and second ends of the elongated magnetic core, wherein the first and second wireless power receiving coils are configured to receive the wireless power from the at least one wireless power transmission coil, the elongated magnetic core has first and second pillars that protrude from the elongated magnetic core at the first and second ends, respectively, and the first and second pillars extend perpendicular to the display. 
 
     
     
       18. The wireless power receiving device of  claim 17  wherein the at least one wireless power transmission coil comprises four wireless power transmission coils equally spaced in a ring and wherein the first and second wireless power receiving coils are formed on the first and second pillars, respectively. 
     
     
       19. The wireless power receiving device of  claim 18  wherein the elongated magnetic core has a C shape and lies in a plane that is parallel to the display. 
     
     
       20. The wireless power receiving device of  claim 18  further comprising a third power receiving coil on the elongated metal core between the first and second wireless power receiving coils.

Description:
This application claims the benefit of provisional patent application No. 62/828,931, 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 or charging puck 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 a coil in 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. During operation, the wireless power transmitting device transmits wireless power to the wireless power receiving device. The wireless power receiving device receives the wireless power using coils and rectifier circuitry. The rectifier circuitry supplies a corresponding output voltage to a load. 
     The wireless power transmitting device may be a wireless charging mat with one or more coils or may be a wireless charging puck with one or more coils. In some embodiments, the wireless charging puck may have multiple coils arranged in a ring. 
     The wireless power receiving device may have an elongated magnetic core such as a C-shaped core with pillar-shaped protrusions that protrude orthogonally from the elongated magnetic core at opposing ends of the elongated magnetic core. First and second coils may be formed on the protrusions and a third coil may be formed between the first and second coils. The coils of the wireless power receiving device may be configured to receive magnetic flux emitted by a pair of the coils in the wireless charging puck. 
    
    
     
       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 puck and a corresponding wireless power receiving device such as a wristwatch in accordance with an embodiment. 
         FIG. 4  is a perspective view of an illustrative curved elongated magnetic core with three associated coils in accordance with an embodiment. 
         FIG. 5  is a top view of an illustrative pair of wireless power transmitting coils in a wireless power transmitting device overlapped by an illustrative magnetic core and three wireless power receiving coils in a wireless power receiving device in accordance with an embodiment. 
         FIG. 6  is a side view of an illustrative wireless power system having a charging mat with multiple coils that is transmitting wireless power to a wristwatch device in accordance with an embodiment. 
         FIG. 7  is a top view of an illustrative wireless power receiving device such as a wristwatch device with a C-shaped magnetic core having three coils in accordance with an embodiment. 
         FIG. 8  is a top view of an illustrative magnetic core for a wireless power transmitting device with coils at opposing ends of the core in accordance with an embodiment. 
         FIG. 9  is an illustrative magnetic core with three coils arranged in a ring for a wireless power transmitting device in accordance with an embodiment. 
         FIG. 10  is an illustrative magnetic core with four coils arranged in a ring for a wireless power transmitting device in accordance with an embodiment. 
         FIG. 11  is an illustrative magnetic core with six coils arranged in a ring for a wireless power transmitting device in accordance with an embodiment. 
         FIGS. 12 and 13  are side views of illustrative elongated magnetic cores with wireless power receiving coils for a wireless power receiving device in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A wireless power system includes a wireless power transmitting device such as a wireless charging mat or wireless charging puck. 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. 
     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 or wireless charging puck 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 transmit 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 puck or other wireless transmitting device may have two or more coils, three or more coils, four or more coils, or six or more coils. 
     As the AC currents pass through one or more coils  36 , alternating-current electromagnetic (e.g., magnetic) fields (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 . When the alternating-current electromagnetic fields are received by coil(s)  48 , corresponding alternating-current currents are induced in coil(s)  48 . Rectifier circuitry such as rectifier  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 coil(s)  48  into DC voltage signals for powering device  24 . 
     The DC voltage produced by rectifier  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  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. 
       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 . Rectifier circuitry (e.g., one or more rectifiers  50 ) 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 configurations with multiple coils  48 , switching circuitry may be used to selectively couple one or more desired coils  48  to a rectifier and/or multiple rectifiers may be used. 
       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 puck and in which wireless power receiving device  24  is a wristwatch. Device  12  has housing  90  (e.g., a puck 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. A magnet such as magnet  94  may be mounted in housing  90  to help align and secure device  12  to device  24 . 
     Device  24  may have a housing such as housing  96 . Wrist band  98  (e.g., a wristwatch strap) may be coupled to 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 axis  116  (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 ). A magnet such as magnet  100  (or magnetic material such as an iron bar or other magnetic material) may be mounted in housing  96 . When devices  12  and  24  are placed adjacent to each other, magnetic attachment components such as magnets  94  and  100  may hold devices  12  and  24  together. This allows coil(s)  36  in housing  90  to transmit wireless power to coil(s)  48  in housing  96 . 
     The coil(s) in devices  12  and/or  24  may have any suitable number of turns of wire. The coils may be formed from turns of wire wrapped around cores made of iron, ferrite, or other magnetic material. A perspective view of an illustrative magnetic core and associated coils formed from wire wrapped around the magnetic core is shown in  FIG. 4 . The magnetic core and coils of  FIG. 4  may be used in system  8  (e.g., to form coils  48  in device  24 ). 
     As shown in  FIG. 4 , core  102  may have an elongated shape and may lie in a plane (e.g., the X-Y plane of  FIG. 4 , which is parallel to the plane in which front face F and display  99  of  FIG. 3  lie and which is parallel to the plane in which rear face R lies). Portions of the elongated core may protrude vertically (see, e.g., the protrusions forming pillars P 1  and P 2 , which protrude orthogonally from the elongated core and therefore extend perpendicular to the X-Y plane along dimension Z). 
     Multiple coils  48  can be wrapped around core  102 . Core  102  is formed from magnetic material and has a crescent-shaped main portion MP (sometimes referred to as an elongated C-shaped core, curved elongated core, curved elongated magnetic core, curved elongated core structure, horseshoe core, etc.). Crescent-shaped main portion MP is curved (e.g., main portion MP is bent and therefore curved along its length). A pair of vertically extending protrusions such as vertically extending pillars P 1  and P 2  extend orthogonally from opposing ends of main portion MP (e.g., the elongated core has a pair of protrusions that extend orthogonally with respect to the longitudinal dimension of the elongated core). In configurations in which device  24  is a wristwatch, pillars P 1  and P 2  may extend perpendicularly with respect to the plane containing the display of device  24  (e.g., the wristwatch may have opposing front and rear faces, may have a display that lies in a plane on the front face, and may contain a core  102  that lies between the front and rear faces and has pillars P 1  and P 2  with longitudinal axes that are perpendicular to the plane of the display). With this type of arrangement, pillars P 1  and P 2  extend along pillar axes that are parallel to axis  116  of  FIG. 3 . Core  102  may have a circular cross-sectionals profile, a rectangular cross-sectional profile, or other suitable cross-sectional shape. The footprint (outline when viewed from above) of core  102  may be C-shaped, L-shaped, straight, curved, a shape with one or more straight segments and/or one or more curved segments, and/or other suitable shapes. 
     Coils C 1 , C 2 , and C 3  may be formed from multiple turns of wire  106 . Coils C 1  and C 2  may be wrapped around pillars P 1  and P 2  of core  102 , respectively. Coil terminals  104  may be coupled to rectifier circuitry in device  24 . In some configurations, two or more coils may be coupled in series (e.g., using switching circuitry or hardwired signal paths). For example, coils C 1  and C 2  may be coupled in series and may operate electrically as a single coil with terminals coupled to rectifier  50 . The winding orientations of coils C 1  and C 2  in this type of configuration may be complementary (e.g., coil C 1  may use clockwise windings and coil C 2  may use counterclockwise windings). In this way, current in the combined C 1 /C 2  coil is generated as magnetic flux passes into pillar P 1  (see, e.g., magnetic field B 1 ) and exits pillar P 2  (see, e.g., magnetic field B 2 ). Coil C 3  may be formed from turns of wire  106  that are wrapped around the same common magnetic core as coils C 1  and C 2  (e.g., magnetic core  102 ). Core C 3  may be used to receive wireless power signals in configurations in which coils C 1  and C 2  are not well positioned to receive magnetic flux from device  12 . 
       FIG. 5  is a top view of magnetic coil core  102  and coils C 1 , C 2 , and C 3  in an illustrative configuration in which device  24  has been placed flat on a charging surface of a wireless power transmitting device that has at least two wireless power transmitting coils  36 A and  36 B. Device  24  may be, for example, a wristwatch placed rear face down on the charging surface of a charging mat. In the example of  FIG. 5 , core  102  is overlapping both of coils  36 A and  36 B, so transmitting device  12  can drive both of coils  36 A and  36 B. Device  12  may, for example, enhance power transfer efficiency by driving coils  36 A and  36 B 180° out of phase with respect to each other. When coils  36 A and  36 B are driven 180° out of phase, magnetic flux (see, e.g., magnetic field B 1 ) will be generated in the center of coil  36 A, will pass through coil C 1  and pillar P 1 , will be guided through core  102  and coil C 3 , will pass through coil C 2  and pillar P 2 , and will be received in the center of coil  36 B (see, e.g., magnetic field B 2 ). In this illustrative scenario, wireless power can be received using coils C 1 , C 2 , and C 3 . 
       FIG. 6  is a side view of magnetic coil core  102  and coils C 1 , C 2 , and C 3  in an illustrative configuration in which device  24  has been placed on its edge on a charging surface of a wireless power transmitting device that has at least two wireless power transmitting coils  36 A and  36 B. Device  24  may be, for example, a wristwatch resting on its left or right edge on the charging surface of a charging mat and supported in this position by band  98 . In the example of  FIG. 6 , core  102  is overlapping both of coils  36 A and  36 B, so device  12  can drive both of coils  36 A and  36 B (e.g., coils  36 A and  36 B may be driven 180° out of phase to enhance power transmission efficiency). When coils  36 A and  36 B are driven 180° out of phase, magnetic flux (see, e.g., magnetic field B 1 ) will be generated in the center of coil  36 A, will pass through coil C 3  and portions of core  102 , and will be received in the center of coil  36 B (see, e.g., magnetic field B 2 ). In this illustrative scenario, coils C 1  and C 2  may not receive as much magnetic flux as in the scenario of  FIG. 5 , but due to the presence of laterally oriented coil (solenoid) C 3 , wireless power transfer may still be possible even though device  24  is resting on the edge of housing  96 . 
     As shown in the top view of illustrative device  24  of  FIG. 7 , core  102  may be located closer to one peripheral edge of housing  96  (e.g., the right-hand edge) than another (e.g., the left-hand edge). This positioning of core  102  may help create space (see, e.g., antenna volume  110 ) within the interior of housing  96  for antennas (e.g., space for one or more antenna resonating elements such as antenna resonating element  111  and associated antenna ground structures for forming cellular telephone antennas, near-field communications antennas, millimeter wave antennas, wireless local area network antennas, and/or other radio-frequency communications circuitry). Antenna resonating element  111  may include metal traces and/or other conductive structures for forming one or more patch antennas, inverted-F antennas, loop antennas, monopoles, dipoles, etc. Control circuitry  16  may include radio-frequency transceiver circuitry that operates at communications frequencies of 700 MHz to 2700 MHz, at frequencies above 2700 MHz (e.g., at local area network frequencies of 2.4 GHz and/or 5 GHz), at frequencies above 5 GHz, at millimeter wave frequencies, or other suitable communications frequencies. These frequencies, which are above 1 Mhz, may differ from the frequency of the wireless power signals transmitted from device  12  to device  24  (which may be, for example, less than 1 MHz, less than 500 kHz, etc. The use of a C-shape (crescent shape) for core  102  may also help create interior volume (see, e.g., area  112 ) for battery  58 , input-output devices  56 , and other electrical components in housing  96 . The use of communications frequencies for the antenna(s) in antenna volume  110  that differ from the wireless power frequencies used in receiving wireless power with the coil structures of device  12  (e.g., coils C 1 , C 2 , and C 3  in the example of  FIG. 7 ) may help avoid interference. 
     Device  12  may have one or more coils  36  for transmitting wireless power signals to device  24 . A single magnetic core may be shared between two or more of these coils or each coil  36  may optionally have a separate magnetic core. In the example of  FIG. 8 , transmitting device magnetic core  114  for device  12  has opposing first and second ends with vertically extending protrusions forming pillars P 1 ′ and P 2 ′, each with a respective one of a pair of first and second coils  36 . Magnetic core  114  and coils  36  of  FIG. 8  may, as an example, be mounted in a wireless charging puck housing (see, e.g., housing  90  of  FIG. 3 ). The spacing between coils  36  of  FIG. 8  may be configured to match the spacing between coils C 1  and C 2  on core  102  of device  24  (see, e.g.,  FIG. 7 ). In this way, magnetic flux can be efficiently coupled out of a first of coils  36  into coil C 1  and, after being guided through core  102 , may be efficiently coupled out of coil C 2  into the second of coils  36 . 
     It may be desirable to permit housing  96  and housing  90  to rotate with respect to each other (e.g., about a rotational axis aligned with axis  116  of  FIG. 3 ). For example, there may be a single magnetic attachment structure (e.g., magnet  94 ) in housing  90  and a single magnetic attachment structure (e.g., magnet  100 ) in housing  96 . These magnetic elements may be located in the centers of housing  96  and housing  90 . This helps couple and laterally align housings  96  and  90 , but may not ensure a desired rotational alignment between housing  90  and housing  96  about axis  116 . 
     To help promote electromagnetic coupling (e.g., magnetic field coupling) between coils  36  and coils  48  (e.g., coils C 1  and C 2  of  FIG. 7  and/or other coils  48  in device  24 ), it may be desirable to provide three or more coils  36  in device  12 . These coils may share a common magnetic core and/or multiple magnetic cores may be provided to accommodate multiple coils  36 . 
       FIG. 9  is a top view of coils  36  for device  12  in an illustrative arrangement in which device  12  has three of coils  36 . Coils  36  may be formed, respectively on vertically extending protrusions forming vertically extending pillars P 1 ′, P 2 ′, and P 3 ′ of shared annular (ring-shaped) magnetic core  114  (as an example). If desired, other core structures may be used (e.g., each coil may have its own core, core  114  may be segmented and/or may have different shapes, etc.). In an embodiment, any adjacent pair of coils  36  can be used to drive signals into and out of respective coils  48 . Due to the use of three coils  36  that are spaced apart by 120°, the alignment between coils  48  and coils  36  can accommodate rotational misalignment within +/−60°. 
       FIG. 10  is a top view of coils  36  for device  12  showing how device  12  may have four of coils  36 . Coils  36  may be formed, respectively on vertically extending protruding portions of shared annular (ring-shaped) magnetic core  114  that form pillars P 1 ′, P 2 ′, P 3 ′, and P 4 ′. Other core structures may be used, if desired. For example, each coil  36  may have its own core, core  114  may be segmented and/or may have different shapes, etc. 
     In the example of  FIG. 11 , device  12  has six coils  36 . Coils  36  may be formed, respectively, on vertically extending portions of shared annular (ring-shaped) magnetic core  114  that form pillars P 1 ′, P 2 ′, P 3 ′, P 4 ′, P 5 ′, and P 6 ′. Other core structures may be used, if desired. For example, each coil  36  may have its own core, core  114  may be segmented and/or may have different shapes, etc. In an embodiment, any adjacent pair of coils  36  or, if desired, any pair of opposing coils  36 , can be used in driving signals into and out of respective coils  48 . Due to the use of four coils  36  each of which is spaced 90° from the next, the alignment between coils  48  and coils  36  can accommodate rotational misalignment within +/−45°. 
     As illustrated by the foregoing examples, rings  36  may be arranged in a cluster (e.g., in a layout such as a circular ring pattern or other suitable pattern) within device  12 . Particularly in arrangements with larger numbers of coils  36 , the cluster of coils  36  may allow some rotational freedom between devices  12  and  24  while still ensuring that satisfactory electromagnetic coupling between devices  12  and  24  may be achieved. Consider, as an example, the six-coil arrangement of  FIG. 11 . In this arrangement, coils  36  are evenly distributed around a circular ring-shaped magnetic core, so that coils  36  are spaced 60° apart from each other. The spacing between the coils of device  24  (e.g., the distance across the ring of  FIG. 11 ) may match the spacing between coils  48  of device  24  (e.g., the spacing between coils C 1  and C 2  in  FIG. 7 ). With the six-coil arrangement of  FIG. 11 , there are  6  different rotational positions (positions as housing  96  is rotated relative to housing  90  about rotational axis  116 ) in which a pair of coils  48  (e.g., coils C 1  and C 2  of  FIG. 7 ) will align with a mating pair of opposing coils  36  in  FIG. 11  (e.g., first and second coils  36  on opposing sides of core  114 . As a result, the amount of potential rotational mismatch between coils  36  and coils  48  is never more than 30°. 
     During initial set-up operations, device  12  may use measurement circuitry  41  (and, if desired, measurement circuitry  43  may be used) to determine which of coils  36  can be satisfactorily used to transmit wireless power to coils  48 . As an example, if coils C 1  and C 2  of device  24  overlap respective first and second opposing coils of device  12  such as coils  36 ′ of  FIG. 11 , the wireless power transmitting circuitry of device  12  can be configured by circuitry  16  (e.g., using switching circuitry, inverter circuitry, etc.) to drive AC signals through those coils. The first and second coils  36 ′ may be driven separately (e.g., a first of coils  36 ′ may receive a first drive signal and a second of coils  36 ′ may receive a second drive signal such as a drive signal that is 180° out of phase with respect to the first drive signal) or a hardwired connection may be formed between coils  36 ′ that couples coils  36 ′ in series. 
     For example, opposing coils may be electrically coupled using wires. As shown in  FIG. 11 , a pair of coils  36 ′ on opposing sides of the ring of coils in device  12  may be electrically coupled using a wire such as wire  120 . Wire  120  may couple a first of coils  36 ′ to a second of coils  36 ′. With this arrangement, a first of coils  36 ′ has a terminal that is coupled to wire  120  and a second of coils  36 ′ has a terminal that is coupled to wire  120 . The first and second coils  36 ′ each have one free terminal  104  that is not connected to wire  120 . The winding sense of the first and second coils may be reversed with respect to each other (e.g., the first coil  36 ′ may be have turns that are wound about pillar P 2 ′ clockwise and the second coil  36 ′ may have turns that are wound around opposing pillar P 5 ′ counterclockwise). Because coils  36 ′ are coupled in series in this example, current that is applied to the free terminal of the first coil  36 ′ flows through the first coil  36 ′, through wire  120 , and through the second coil  36 ′ to the free terminal of the second coil  36 ′. The clockwise orientation of the windings for the first coil  36 ′ creates magnetic flux from the first coil  36 ′ that has a first orientation (called north N in  FIG. 11 , which may be out of the page of  FIG. 11 ). At the same time, the counterclockwise orientation of the windings for the second coil  36 ′ creates magnetic flux from the second coil  36 ′ that has an opposing second orientation (called south S in  FIG. 11 , which may be into the page of  FIG. 11 ). Coils  48  (e.g., coils C 1  and C 2  on core  102  of  FIG. 7 ) likewise have windings with opposing orientations (giving coil C 1  a south orientation, for example, and giving coil C 2  a north orientation). As a result, magnetic flux is emitted from the first coil  36 ′ into coil C 1 , passes through core  102 , and passes out of coil C 2  into the second coil  36 ′. 
       FIGS. 12 and 13  are side views of coils  48  in device  24 . In the example of  FIG. 12 , coils C 1 , C 2 , and C 3  are formed on a common magnetic core  114 . Core  114  may have a thickness T 1  of about 0.5 mm or other suitable thickness. The height T 2  of core  114  at pillars P may be about 1.5 mm or other suitable thickness. The width of core  114  (e.g., the lateral dimension of core  114  into the page in the example of  FIG. 12 ) may be about 2.5 mm or other suitable size. Core  114  may be formed from magnetic material such as ferrite or other magnetic material. Core  114  may have an elongated shape that is straight or curved when viewed from above in direction  122  (e.g., to form a horseshoe shape, sometimes referred to as a C shape, or other suitable magnetic core shape). In the example of  FIG. 13 , coil C 3  has been formed on magnetic core  114 ′, which is separate from main magnetic core  114  of  FIG. 13 . In this type of arrangement, coil C 3  may be located farther from internal components in region  120  in which eddy currents may be induced by current flow through coil C 3  and associated electromagnetic emissions. The location of magnetic core  114 ′ of  FIG. 13  may also allow core  114  to serve as electromagnetic shielding (e.g., core  114  may help block magnetic fields from coil C 3  that might otherwise induce eddy currents in components located in region  120 ). 
     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: 20190703
Publication Date: 20220215
Grant Date: 20220215
Priority Date: 20190403
Inventors: REN, SAINING
LEUNG, HO FAI
CHEN, LIANG
Assignee: APPLE INC
CPC Classifications: [{"code": "H01F38/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M7/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M3/315", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/2823", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02M3/315", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01F27/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/2823", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M7/12", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 72663223