PATENT DOCUMENT

Publication Number: US-10873221-B1
Application Number: US-201815866271-A
Country: US
Kind Code: B1

Title: Wireless power control system

Abstract:
Wireless power transmitting equipment has a wireless power transmitter that includes a power converter and a radio-frequency inverter. The radio-frequency inverter may have an output coupled to a transmitting coil circuit formed from a capacitor coupled in series with a wireless power transmitting coil. Feedback information such as information on an output voltage from a rectifier in wireless power receiving equipment is wirelessly transmitted to the wireless power transmitting equipment. Signal phase and amplitude information such as the rectifier output voltage, current measurements in the wireless power receiver, and current and voltage phase and amplitude measurements made using a voltage sensor across the radio-frequency inverter output and a current sensor in series with the transmitting coil circuit may be used by the wireless power transmitting equipment to control the wireless power transmitter and thereby adjust wireless power transmission levels.

Claims:
What is claimed is: 
     
       1. Wireless power transfer equipment, comprising:
 a transmitting coil circuit comprising a wireless power transfer coil and a capacitor; 
 a radio-frequency inverter that is coupled to the transmitting coil circuit and that is configured to provide alternating-current signals to the transmitting coil circuit, wherein the transmitting coil circuit is configured to transmit wireless power at a wireless power transmission level to wireless power receiving equipment that is movable relative to the wireless power transfer coil when provided with the alternating-current signals; 
 signal monitoring circuitry coupled to the transmitting coil circuit and configured to gather a signal phase measurement and a signal amplitude measurement; and 
 control circuitry configured to, while the wireless power receiving equipment is powering a load at the wireless power receiving equipment using the transmitted wireless power:
 receive the signal phase measurement and the signal amplitude measurement from the signal monitoring circuitry, 
 receive, using the wireless power transfer coil, wirelessly transmitted feedback information from the wireless power receiving equipment, 
 control the radio-frequency inverter to perform a first adjustment of the wireless power transmission level based on the signal phase measurement and the signal amplitude measurement, and 
 once the feedback information is available at the control circuitry, control the radio-frequency inverter to perform a second adjustment of the wireless power transmission level by computing a parameter that is a function of the feedback information and the signal phase measurement and signal amplitude measurement, wherein the second adjustment is subsequent to the first adjustment. 
 
 
     
     
       2. The wireless power transfer equipment defined in  claim 1  wherein the radio-frequency inverter has first and second output terminals and wherein the signal monitoring circuitry includes a voltage sensor coupled across the first and second output terminals. 
     
     
       3. The wireless power transfer equipment defined in  claim 2  wherein the signal monitoring circuitry comprises a current sensor coupled in series with the wireless power transfer coil. 
     
     
       4. The wireless power transfer equipment defined in  claim 3  wherein the voltage sensor comprises:
 a voltage phase measurement circuit configured to supply a voltage phase measurement; and 
 a voltage amplitude measurement circuit configured to supply a voltage amplitude measurement. 
 
     
     
       5. The wireless power transfer equipment defined in  claim 4  wherein the current sensor comprises:
 a current phase measurement circuit configured to supply a current phase measurement; and 
 a current amplitude measurement circuit configured to supply a current amplitude measurement. 
 
     
     
       6. The wireless power transfer equipment defined in  claim 5  wherein the feedback information includes wirelessly transmitted information on current phase and amplitude associated with a rectifier of the wireless power receiving equipment and voltage phase and amplitude associated with the rectifier of the wireless power receiving equipment. 
     
     
       7. The wireless power transfer equipment defined in  claim 6  further comprising an alternating-current-to-direct-current converter configured to supply direct-current power to the radio-frequency inverter. 
     
     
       8. The wireless power transfer equipment defined in  claim 1  wherein the control circuitry is configured to determine a load resistance of wireless power receiving equipment that receives wirelessly transmitted power from the transmitting coil circuit. 
     
     
       9. The wireless power transfer equipment defined in  claim 8  wherein the control circuitry is configured to determine the load resistance based at least partly on the signal phase measurement and the signal amplitude measurement. 
     
     
       10. The wireless power transfer equipment defined in  claim 9  wherein the signal phase measurement and the signal amplitude measurement include current phase and amplitude information for current signals passing through the wireless power transfer coil and wherein the signal phase measurement and the signal amplitude measurement includes voltage phase and amplitude information associated with an output of the radio-frequency inverter. 
     
     
       11. The wireless power transfer equipment defined in  claim 1 , wherein the feedback information includes rectifier output current information associated with a rectifier in the wireless power receiving equipment and rectifier output voltage information associated with the rectifier in the wireless power receiving equipment and wherein the control circuitry is further configured to:
 determine a last known coupling value between the transmitting coil circuit and the wireless power receiving equipment based on a last known rectifier output voltage, a last known rectifier output current, and the signal phase and amplitude information; and 
 control the radio-frequency inverter to adjust the wireless power transmission level based at least partly on the last known coupling value. 
 
     
     
       12. The wireless power transfer equipment defined in  claim 1 , wherein the wirelessly transmitted feedback information comprises a first voltage value and a first current value generated by the wireless power receiving equipment, wherein the signal phase measurement and the signal amplitude measurement comprise a second voltage value and a second current value gathered by the signal monitoring circuitry, and wherein the control circuitry is further configured to:
 generate a coupling value as a function proportional to a square root of the first voltage value multiplied by the second voltage value and divided by the first current value and the second current value; and 
 control the radio-frequency inverter to perform the second adjustment based on the generated coupling value. 
 
     
     
       13. Wireless power transmitting equipment, comprising:
 a wireless power transmitting coil; 
 a wireless power transmitter circuit coupled to the wireless power transmitting coil and configured to provide alternating-current signals to the wireless power transmitting coil, wherein the wireless power transmitting coil is configured to wirelessly transmit power at a wireless power transmission level to wireless power receiving equipment when provided with the alternating-current signals, wherein the wireless power receiving equipment is movable relative to the wireless power transmitting coil; 
 signal monitoring circuitry coupled to the wireless power transmitting coil that is configured to gather signal phase and amplitude measurements; and 
 control circuitry configured to, while the wireless power receiving equipment is powering a load at the wireless power receiving equipment using the transmitted wireless power:
 receive, using the wireless power transmitting coil, wirelessly transmitted feedback information from the wireless power receiving equipment, 
 control the wireless power transmitter circuit to perform a first adjustment of the wireless power transmission level based on the signal phase and amplitude measurements, and 
 control the wireless power transmitter circuit to perform a second adjustment of the wireless power transmission level by computing a value dependent on the feedback information and the signal phase and amplitude measurements, wherein the second adjustment is subsequent to the first adjustment. 
 
 
     
     
       14. The wireless power transmitting equipment defined in  claim 13  further comprising a capacitor coupled in series with the wireless power transmitting coil that forms a transmitting coil circuit, wherein the wireless power transmitter circuit comprises a radio-frequency inverter coupled to the transmitting coil circuit. 
     
     
       15. The wireless power transmitting equipment defined in  claim 14  wherein the radio-frequency inverter has first and second output terminals coupled to the transmitting coil circuit and wherein the signal monitoring circuitry comprises a voltage sensor coupled between the first and second output terminals. 
     
     
       16. The wireless power transmitting equipment defined in  claim 15  wherein the signal monitoring circuitry comprises a current sensor coupled in series with the wireless power transmitting coil. 
     
     
       17. Wireless power transmitting equipment, comprising:
 a transmitting coil circuit comprising a wireless power transfer coil and a capacitor; 
 a radio-frequency inverter that has an output that is coupled to the transmitting coil circuit and that is configured to provide alternating-current signals to the transmitting coil circuit, wherein the transmitting coil circuit is configured to transmit wireless power at a wireless power transmission level when the alternating-current signals are provided to the transmitting coil circuit; 
 a current sensor; 
 a voltage sensor; and 
 control circuitry configured to:
 gather a current measurement from the current sensor and a voltage measurement from the voltage sensor, 
 receive wirelessly transmitted information associated with a rectifier output voltage from wireless power receiving equipment that is movable relative to the wireless power transfer coil and that has a load that is powered by the wireless power, 
 compute an effective load resistance of the load of the wireless power receiving equipment as a function of the wirelessly transmitted information, the current measurement, and the voltage measurement, and 
 detect a fault condition associated with the wireless power receiving equipment based on the computed effective load resistance. 
 
 
     
     
       18. The wireless power transmitting equipment defined in  claim 17  wherein the current sensor comprises:
 a current phase measurement circuit configured to supply a current phase measurement to the control circuitry; and 
 a current amplitude measurement circuit configured to supply a current amplitude measurement to the control circuitry. 
 
     
     
       19. The wireless power transmitting equipment defined in  claim 18  wherein the voltage sensor comprises:
 a voltage phase measurement circuit configured to supply a voltage phase measurement to the control circuitry; and 
 a voltage amplitude measurement circuit configured to supply a voltage amplitude measurement to the control circuitry, wherein the voltage sensor is coupled to the output of the radio-frequency inverter and wherein the current sensor is coupled in series with the transmitting coil circuit. 
 
     
     
       20. The wireless power transmitting equipment defined in  claim 17 , wherein the function is inversely proportional to the voltage measurement and directly proportional to a square of a coupling value, and wherein the control circuitry is further configured to:
 compute the coupling value as an additional function that is directly proportional to a square root of the voltage measurement divided by the current measurement, wherein the additional function is directly proportional to a square root of an additional voltage measurement from the wirelessly transmitted information divided by an additional current measurement from the wirelessly transmitted information.

Description:
This application claims the benefit of provisional patent application No. 62/452,877, filed on Jan. 31, 2017, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to wireless systems, and, more particularly, to systems in which power is transferred wirelessly. 
     BACKGROUND 
     In a wireless power transfer system, a wireless power transmitting device such as charging mat may wirelessly transmit power to wireless power receiving equipment. The wireless power receiving equipment may use this power to charge a battery. During wireless power transfer operations, power transfer conditions may change. For example, magnetic coupling between transmitting and receiving coils may vary, which may potentially disrupt the wireless power transfer process. 
     SUMMARY 
     Wireless power transmitting equipment may transmit wireless power signals to wireless power receiving equipment. The wireless power transmitting equipment may have a transmitter that includes a power converter and a radio-frequency inverter. The radio-frequency inverter may have an output coupled to a transmitting coil circuit. The transmitting coil circuit may include a wireless power transmitting coil coupled in series with a capacitor. During operation, wireless power may be transmitted at a wireless power transmission level from the wireless power transmitting equipment to the wireless power receiving equipment. 
     The wireless power receiving equipment may have a rectifier coupled to a receiving coil circuit. The receiving coil circuit may have a wireless power receiving coil coupled in series with a capacitor. A rectifier may rectify signals from the receiving coil circuit to produce direct-current power. The wireless power receiving equipment may have a voltage sensor coupled to an output of the rectifier that gathers rectifier output voltage phase and amplitude information. The wireless power receiving equipment may also have a current sensor that measures rectifier output current phase and amplitude information. Feedback information such as the current and voltage phase and amplitude information that has been gathered in the wireless power receiving equipment may be wirelessly transmitted to the wireless power transmitting equipment for use in controlling the wireless power transmission level. 
     The wireless power transmitting equipment may have a voltage sensor and a current sensor for making signal phase and amplitude measurements. The voltage sensor may monitor the output of the radio-frequency inverter and the current sensor may be coupled in series with the transmitting coil circuit in the wireless power transmitting equipment to monitor transmitting coil circuit current. Control circuitry in the wireless power transmitting equipment may use current and voltage phase and amplitude measurements from the voltage and current sensors in the wireless power transmitting equipment and the feedback information from the wireless power receiving equipment in controlling the radio-frequency inverter and other transmitter circuitry in the wireless power transmitting equipment. The control circuitry may control the transmitter circuitry to adjust the wireless power transmission level between the wireless power transmitting equipment and the wireless power receiving equipment. 
     During operation, the wireless power transmitting equipment may sometimes be called upon to make relatively fast adjustments such as adjustments to accommodate load changes arising from load faults or other rapid load changes. The wireless power transmitting equipment may also be called upon to make slower changes such as those associated with component aging, temperature fluctuations, and fluctuations in electromagnetic coupling (coupling coefficient) between transmitting and receiving coils. The current and voltage measurements made in the wireless transmitting equipment can be used to produce feed forward information that is immediately available to help in controlling wireless power transmitter operation in response to rapid transients such as those associated with load changes. The current and voltage measurements made in the wireless receiving equipment can be used in producing accurate feedback information that is available to help in controlling wireless power transmitter operation in response to slower fluctuations such as those associated with temperature changes, changes in magnetic coupling, and component aging. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative wireless charging system in accordance with some embodiments. 
         FIG. 2  is a schematic diagram of illustrative wireless charging system circuitry in accordance with an embodiment. 
         FIG. 3  is a diagram of illustrative current sensing equipment in accordance with an embodiment. 
         FIG. 4  is a diagram of illustrative voltage sensing equipment in accordance with an embodiment. 
         FIG. 5  is a flow chart of illustrative operations involved in controlling a wireless charging system in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A wireless power transfer system may have wireless power transfer equipment such as wireless power transmitting equipment that transmits power and corresponding wireless power receiving equipment that receives wirelessly transmitted power. 
     The wireless power transmitting equipment may be equipment such as a wireless charging mat, wireless charging station, wireless charging puck, wireless charging stand, wireless charging table, or other wireless power transmitting equipment. The wireless power transmitting equipment may have one or more coils that are used in transmitting wireless power to wireless power receiving equipment. The wireless power receiving equipment may be an electronic device such as a portable electronic device, a vehicle, or other electronic equipment that receives wirelessly transmitted power. 
     During operation, the wireless power transmitting equipment may supply alternating-current signals to one or more wireless power transmitting coils. This causes the coils to transmit alternating-current electromagnetic signals (sometimes referred to as wireless power signals) to the wireless power receiving equipment. The wireless power receiving equipment may have one or more coils for receiving the transmitted wireless power signals. 
     An illustrative wireless power system (wireless charging system) is shown in  FIG. 1 . As shown in  FIG. 1 , wireless power system  8  may include wireless power transfer equipment such as wireless power transmitting equipment  12  and wireless power receiving equipment  10 . 
     Power transmitting equipment  12  may be a mat, equipment built into a parking space, circuitry built into furniture or part of a vehicle, a charging stand, an electronic device such as a portable electronic device or desktop equipment, or may be other power transmitting equipment. For example, power transmitting equipment  12  may be a wireless charging mat or other wireless charger that rests under a vehicle during wireless charging. Equipment  10  may be a vehicle, an electronic device, or other wireless power receiving equipment. 
     Wireless power transmitting equipment  12  may have one or more power transmitting coils such as wireless power transmitting (wireless power transfer) coil(s)  30 . Wireless power transmitter circuitry such as wireless power transmitter  32  may provide alternating current signals to coil(s)  30  that cause coil(s)  30  to emit electromagnetic fields  26  that are near-field coupled to corresponding wireless power receiving coil(s)  20  in wireless power receiving equipment  10 . Rectifier  18  may rectify received signals from coil(s)  20  and may produce corresponding direct-current (DC) power for equipment  10 . 
     Power transmitting equipment  12  may have a power source such as power source  38 . Power source  38  may be a source of alternating-current (AC) voltage such as a wall outlet that supplies line power or other source of mains electricity or a source of direct-current voltage such as a battery. Power transmitting equipment  12  may have a power converter such as an AC-DC power converter for converting power from a mains power source or other power source into DC power. Power source  38  may be used to power control circuitry  34  and components  36  in equipment  12  and may be used to provide transmitter  32  with power to transmit to equipment  10 . In equipment  10 , power from rectifier  18  may be used to charge battery  22  and to power control circuitry  14  and components  16 . Components  36  and  16  may include light-emitting components, displays, buttons, sensors, wireless communications circuitry, audio equipment and/or other input-output devices and components for supporting the operation of equipment  12  and/or  10 . In some configurations, components  36  and  16  in equipment  10  and/or  12  may include motors, transmissions, steering systems, seating, body panels, doors and windows, and other vehicle components. 
     Control circuitry  34  and  14  may include storage and may include processing circuitry such as microprocessors, power management units, baseband processors, digital signal processors, microcontrollers, and/or application-specific integrated circuits with processing circuits. Control circuitry  34  and  14  may be configured to execute instructions for implementing desired control and communications features in system  8 . For example, control circuitry  34  and/or  14  may be used in determining power transmission levels, processing sensor data, processing user input, processing other information such as information on wireless coupling efficiency from transmitting circuitry  32 , processing information from wireless power receiving circuitry in equipment  10  such as rectifier  18 , using information from sensors in components  16  and/or  36  to determine when to start and stop wireless charging operations, adjusting charging parameters such as charging frequencies, coil assignments in a multi-coil array, and wireless power transmission levels, and performing other control functions. 
     Control circuitry  34  and/or  14  may be configured to perform these operations using hardware (e.g., dedicated hardware or circuitry) and/or software (e.g., code that runs on the hardware of system  8 ). Software code for performing these operations may be stored on non-transitory computer readable storage media (e.g., tangible computer readable storage media). 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, other computer readable media, or combinations of these computer readable media. Software stored on the non-transitory computer readable storage media may be executed on the processing circuitry of control circuitry  34  and/or  14 . The processing circuitry may include application-specific integrated circuits with processing circuitry, one or more microprocessors, or other processing circuitry. 
     Control circuitry  34  and/or  14  may include wireless communications circuitry. If desired, circuitry  34  and  14  may include antennas and associated radio-frequency transceiver circuitry (e.g., circuitry operating at 2.4 GHz or other suitable communications frequencies). Circuitry  34  and/or  14  may also communicate wirelessly over the wireless link formed by signals  26 . For example, control circuitry  14  may include a transmitter that is coupled across coil(s)  20 . This transmitter may be used to modulate the impedance of coil(s)  20  to transmit data to equipment  10  as wireless signals  26  are being conveyed from equipment  12  to equipment  10  to transfer power wirelessly from equipment  12  to equipment  10 . By modulating the impedance of coil(s)  20 , a corresponding detectable change in the impedance of coil(s)  30  may be produced at equipment  12 . A receiver in equipment  12  can detect these impedance changes at coil(s)  30  and can perform demodulation operations to recover the data transmitted from equipment  10 . 
     Wireless data transmissions from equipment  10  to equipment  12  may be used to provide equipment  12  with feedback during wireless power transfer operations. If, as an example, changes in the operating environment of system  8  give rise to changes in the wireless power transfer operations for system  8 , equipment  10  may provide wireless feedback signals to equipment  12  that inform equipment  12  of the changes. Measured fluctuations in rectifier output voltage and current may, for example, be conveyed wirelessly to equipment  12 . This allows equipment  12  to make corrective adjustments to the wireless power signals being transmitted from equipment  10  and  12 . Wireless feedback information may be provided from equipment  10  to equipment  12  by using a transmitter and antenna in control circuitry  14  to transmit wireless data to a corresponding antenna and receiver in control circuitry  34  or may be provided by using a transmitter in circuitry  14  to modulate the impedance of coil  20  and thereby wirelessly transmit data to coil  30  and an associated receiver in control circuitry  34 . 
     Regardless of the type of wireless communications arrangement that is used to wirelessly convey wireless power transfer feedback information from equipment  10  to equipment  12 , such communications may have an associated latency. This latency can potentially limit the speed with which control circuitry  34  can make changes to the operation of wireless power transmitting equipment  12 . To overcome control speed limitations associated with latency in wirelessly receiving feedback information from equipment  10 , system  8  can use a hybrid control technique in which control decisions are based on both on wirelessly received feedback information from equipment  10  and more direct locally gathered real-time information from sensor circuitry in equipment  12 . Locally gathered information from the sensor circuitry in equipment  12  may serve as feed-forward information that can help control circuitry  34  act promptly to changed operating conditions. With one illustrative configuration, control circuitry  34  in equipment  12  can dynamically adjust the operation of equipment  12  based on both the feed-forward information gathered from the sensors of equipment  12  (which exhibits low latency) and feedback information from equipment  10  (which accurately reflects the output of rectifier  18 ). 
       FIG. 2  is a circuit diagram showing circuitry for system  8  that allows equipment  12  to be controlled using both wirelessly received feedback from equipment  10  and real-time measurements of parameters associated with the operation of transmitter  32  and coil(s)  30 . Equipment  12  may, for example, receive information on the current and output voltage being delivered by rectifier  18  in equipment  10  wirelessly from equipment  10 , while making real-time measurements of the current and voltage associated with transmitting wireless power using transmitter  32  and coil(s)  30 . The wirelessly received information from equipment  10  may be used to provide feedback information and the information measured in equipment  12  may be used to provide feed-forward information. Both the feed-forward and feedback information may be used by equipment  12  in dynamically adjusting the wireless transfer of power from equipment  12  to equipment  10 . 
     As shown in  FIG. 2 , equipment  12  may receive power from power source  38  at input  54 . The received power may be, for example, mains power from an alternating current source. Alternating-current (AC) power may be converted to direct-current (DC) power using AC-DC converter  40 . Radio-frequency inverter  42  may create a radio-frequency drive signal from DC-power (DC voltage) received from converter  40 . The radio-frequency drive signal may be, for example, a signal at 85 kHz, at 10-300 kHz, at more than 50 kHz, at less than 200 kHz, or other suitable frequency. This alternating current drive signal may be supplied to a transmitting coil circuit formed from capacitor C 1  and coil L 1 , which causes the transmitting coil circuit to emit alternating-current magnetic fields (fields  26 ). Inverter  42  may, for example, have a pair of output terminals coupled to capacitor C 1  and an appropriate one or more of coils  30  such as wireless power transfer coil (inductor) L 1 . Equipment  12  may have monitoring circuitry such as voltage sensor  44  and current sensor  46 . Voltage sensor  44  may be coupled between the output terminals of inverter  42  and current sensor  46  may be coupled in series with the transmitting coil circuit formed from capacitor C 1  and coil L 1 . Control circuitry  34  may use real-time measurements from the monitoring circuitry in equipment  12  and wirelessly received feedback information from equipment  10  in controlling equipment  12  (e.g., in controlling converter  40  and/or inverter  42 ). 
     Coil L 1  may be magnetically coupled to wireless power transfer coil L 2  in equipment  10 . Coil L 2  may be coupled in series with capacitor C 2  to form a receiving coil circuit in equipment  10 . Coil L 1  and capacitor C 1  may form a transmitting coil circuit in equipment  12  that is used in generating wireless power signals  26 . Coil L 2  and capacitor C 2  may form a corresponding receiving coil circuit in equipment  10  that is used in receiving signals  26 . 
     During operation, magnetic coupling between coils L 1  and L 2  may allow power (signals  26 ) to be transferred wirelessly from equipment  12  to equipment  10 . Rectifier  18  in equipment  10  may convert alternating-current signals in the receiving coil circuit formed from coil L 2  and capacitor C 2  into direct-current output voltage V 2  and associated direct-current output current I 2 . Voltage V 2  may be used to power loads in equipment  10  such as battery system  52  (e.g., a battery charging circuit that controls charging of battery  22  using voltage V 2 ) and components  16 . 
     Equipment  10  may have monitoring circuitry such as circuitry  48  and  50 . Circuitry  48  may be a voltage sensor that measures rectifier output voltage V 2 . Circuitry  50  may be a current sensor that measures rectifier output current I 2 . 
       FIG. 3  is a diagram of illustrative current sensor circuitry for use in the monitoring circuitry of equipment  12  and/or  10 . Current sensor  70  may, for example, be used to implement current sensor circuitry  46  of equipment  12  and/or current sensor circuitry  50  of equipment  10 . As shown in  FIG. 3 , current sensor  70  may measure current flowing between terminals  72  and  74 . Current sensor  70  may include circuitry for making current phase measurements such as current phase measurement circuit  76 , which produces current phase information (the real part of the current being measured) at output  78 . Current sensor  70  may also include circuitry for making current amplitude measurements such as current amplitude measurement circuit  80 , which produces current amplitude information (the imaginary part of the current being measured) at output  82 . 
       FIG. 4  is a diagram of illustrative voltage sensor circuitry for use in the signal monitoring circuitry of equipment  12  and/or  10 . The circuitry of voltage sensor  84  of  FIG. 4  may be used in voltage sensor circuitry  44  of equipment  12  and/or voltage sensor circuitry  48  of equipment  10 . As shown in  FIG. 4 , voltage sensor  84  may measure voltage across terminals  86  and  88 . Voltage sensor  84  may include circuitry for making voltage phase measurements such as voltage phase measurement circuit  90 , which produces voltage phase information (the real part of the voltage being measured) at output  92 . Voltage sensor  84  may also include circuitry for making voltage amplitude measurements such as voltage amplitude measurement circuit  94 , which produces voltage amplitude information (the imaginary part of the voltage being measured) at output  96 . 
     During operation of system  8 , signal monitoring circuitry in system  8  may be used to measure I 1 , V 1 , I 2 , and V 2 . I 2  and V 2  may be wirelessly transmitted from equipment  10  to equipment  10 . 
     The impedance of the transmitting coil circuit formed from coil L 1  and capacitor C 1  may be determined (e.g., by control circuitry  34 ) using equation 1.1, where R L1  is the series resistance of coil L 1 .
 
 Z 1= jωL 1−1/ jωC 1+ R   L1   (1.1)
 
     The impedance of the receiving coil circuit formed from coil L 2  and capacitor C 2  may be determined (e.g., by control circuitry  34 ) using equation 1.2, where R L2  is the series resistance of coil L 2 .
 
 Z 2= jωL 2−1/ jωC 2+ R   L2   (1.2)
 
     Coupling M between coils L 1  and L 2  may then be determined (e.g., by control circuitry  34 ) using equation 1.3.
 
 M =(1/ω)*[|( V 2/ I 2+ Z 2)( V 1/ I 1− Z 1)|] 1/2   (1.3)
 
     Control circuitry  34  may also use equations 2.1-2.3 to determine the values of additional parameters that characterize the performance of system  8 .
 
 P out=Real[ V 1* I 1]  (2.1)
 
 R   L =ω 2   M   2 /( V 1/ I 1− Z 1)− Z 2  (2.2)
 
 V 2=[ P out* R   L ]½  (2.3)
 
     The value of Pout from equation 2.1 represents the power delivered to equipment  12  from equipment  10  and may be used as a low-latency feed-forward element in controlling wireless power delivery to equipment  10 . In equation 2.2, the last known value of M (based on I 2  and V 2  information transmitted wirelessly from equipment  10  to equipment  12 ) may be used in computing R L . The value of R L  in equation 2.2 represents the effective load resistance of the load of equipment  10  and may be used by control circuitry  34  and/or  14  in detecting fault conditions (e.g., R L  may be monitored over time to determine whether the value of R L  has drifted out of an expected range). If a fault condition is detected, power delivery to equipment  10  can be reduced or other suitable actions taken. Voltage V 2  in equation 2.3 is a derived value that is obtained from the known values of Pout and R L  from equations 2.1 and 2.2 and represents the rectifier output voltage in equipment  10 . 
     Illustrative operations involved in controlling system  8  during wireless power transfer operations are shown in the flow chart of  FIG. 5 . 
     During the operations of block  100 , control circuitry  14  of equipment  10  may use current sensor  50  to measure current I 2  and may use voltage sensor  48  to measure voltage V 2 . The measured values of I 2  and V 2  may be transmitted wirelessly from equipment  10  to equipment  12 . 
     During the operations of block  102 , control circuitry  34  of equipment  12  may use current sensor  46  to measure current I 1  and may use voltage sensor  44  to measure voltage V 1 . Phase and amplitude measurements may be made when measuring the voltages and currents of blocks  100  and  102 . 
     During the operations of block  104 , equations 1.1, 1.2, 1.3, 2.1, 2.2, and 2.3 may be used to determine operating parameters of interest for system  8  (e.g., M, Pout, R L , and V 2 ). 
     System  8  may then take appropriate action based on the information that has been gathered (block  106 ). For example, control circuitry  34  may use feedback information such as the measured value of rectifier output voltage V 2  to determine whether V 2  is too high or too low. If the value of V 2  is too low, battery system  52  may not be able to charge battery  22  effectively, so control circuitry  34  can adjust inverter  42  and/or converter  40  to increase power delivery in response to measuring low values of V 2 . Signal measurements make locally with sensors  44  and  46  may be used to provide a feed forward element to the control scheme implemented by control circuitry  12 . As an example, because the value of Pout measured from equation 2.1 is computed at least partly based on the measured values of I 1  and V 1  (which are not affected by wireless transmission latency between equipment  10  and  12 ), the measured value of Pout may be effectively used as a feed forward element that adds a faster (low latency) contribution to the feedback provided by monitoring voltage V 2 . If desired, adjustments may be made immediately upon measuring feed forward information I 1  and V 1  at block  102  and additional adjustments may be made periodically when feedback information is available (e.g., from measurements of the type made in block  100 ). The flow of operations depicted in  FIG. 5  is illustrative. 
     The measured value of RL and/or other information gathered using sensors  48 ,  50 ,  44 , and/or  46  (e.g., M, V 2 , Pout, etc.) may be used to help detect potential fault conditions. In response to detection of a potential fault, control circuitry  12  may supply control signals to converter  40  and/or inverter  42  to reduce (e.g., to temporarily lower or to completely halt) the delivery of wireless power to equipment  10 . Control circuitry  14  may also take actions in response to detection of potential fault conditions (e.g., by switching on protection circuitry, by adjusting battery system  52  and/or other power regulator circuitry in equipment  10 , etc.). In general, control circuitry  14  may adjust the wireless power transmission level for equipment  12  based on signal phase and amplitude information (e.g., feed forward voltage and current information gathered using sensors  44  and  46  and feedback voltage and current information gathered using sensors  48  and  50 ) and/or any other suitable information gathered using the sensors and other circuitry in system  8 . 
     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: 20180109
Publication Date: 20201222
Grant Date: 20201222
Priority Date: 20170131
Inventors: PIERQUET, BRANDON
WU, Hunter H.
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J50/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/0068", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/05", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J7/0091", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/05", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 73823562