Coordinating voltage and frequency variations in wireless power transfer

Abstract

The present disclosure relates to coordinating voltage and frequency changes in wireless power transmission. A wireless transmitter coordinates changes in an input voltage or an output voltage of the transmitter with changes in an operating frequency of the transmitter to offset changes in output power of the transmitter when the voltage is changed. When the voltage is increased, the output frequency is moved away from the resonant frequency. Thus, the increase in output power due to the increase in voltage is suppressed by the frequency change. Prior to or after the voltage is increased, increased output power can be obtained by altering the output frequency while the input and output voltages are held constant or near constant. When the input or output voltage of the transmitter is decreased, similar processes are followed by some embodiments. Calibration is performed prior to power transmission to determine appropriate voltage and frequency curves for voltage change operations. Other features are also provided.

Description

Technical Field

[0001] Embodiments of the present invention relate to wireless power systems, and more particularly to coordinating voltage and frequency variations during wireless power transmission. Some embodiments reduce or avoid undesirable voltage spikes without slowing down power transmission. Background Technology

[0002] Mobile devices such as smartphones, tablets, wearables, and others are increasingly using wireless charging, such as wireless power transfer (WPT). Wireless power transfer can involve: a transmitter driving a transmitting coil to generate a time-varying magnetic field; and a receiver with a receiving coil placed near the transmitting coil. The receiving coil receives the wireless power generated by the transmitting coil and uses the received power to drive a load, such as charging a battery. The receiver coil and the load can be part of a device (such as a mobile phone, PDA, computer, or other device) positioned relative to the transmitter coil to receive the power transmitted in the time-varying magnetic field.

[0003] Currently, there are many different standards for wireless power transfer. More common standards for wireless power transfer include the Wireless Power Alliance (A4WP) standard and the Wireless Power Association standard, as well as the Qi standard. Under the Wireless Power Association Qi specification, a resonant inductive coupling system is used to charge a single device at the resonant frequency of the receiver coil circuit. In the Qi standard, the receiver coil is placed very close to the transmitter coil, while in the A4WP standard, the receiver coil is placed near the transmitter coil and may be placed alongside other receiver coils belonging to other charging devices.

[0004] The wireless power system may further include data communication between the wireless power transmitter and the wireless power receiver. Data communication can be achieved by exchanging data using a transmitting coil and a receiving coil, or by using other channels.

[0005] Preferably, overvoltage conditions and other uncontrolled voltages should be avoided without significantly reducing the wireless power transmission speed. Summary of the Invention

[0006] According to some embodiments of the present invention, the wireless transmitter coordinates its input and / or output voltage with its operating frequency to avoid spikes in both the transmitter output power and the receiver voltage when the transmitter voltage increases. When the transmitter voltage increases, the operating frequency moves away from the resonant frequency to offset (suppress or eliminate) the increase in transmitter output power. If higher output power is desired, it can be obtained before or after the voltage increase by moving the operating frequency closer to the resonant frequency while keeping the transmitter voltage constant or nearly constant.

[0007] When the input or output voltage of the transmitter is reduced, some embodiments follow a similar process: the voltage reduction occurs simultaneously with the frequency shifting closer to the resonant frequency to offset the change in output power.

[0008] These and other embodiments will be further discussed below with reference to the accompanying drawings. Attached Figure Description

[0009] Figure 1 The diagram illustrates a wireless power transmission system.

[0010] Figure 2 The diagram illustrates the relationship between the transmitter's input voltage, output power, and operating frequency.

[0011] Figure 3 This is a flowchart of changing the input voltage of the transmitter.

[0012] Figure 4 , Figure 5 and Figure 6 yes Figure 3 The diagram shows some embodiments of the process.

[0013] Figure 7A The diagram illustrates a wireless power transmitter.

[0014] Figure 7B The illustration shows a device with a wireless power receiver.

[0015] Figure 8 This is a flowchart of the process performed to adjust the transmitter voltage. Detailed Implementation

[0016] In the following description, specific details describing some embodiments of the invention are set forth. However, it will be apparent to those skilled in the art that some embodiments may be practiced without some or all of these specific details. The specific embodiments disclosed herein are intended to be illustrative and not restrictive. Other elements, though not specifically described herein, may be implemented by those skilled in the art within the scope and spirit of this disclosure.

[0017] The description and accompanying drawings illustrating various aspects and embodiments of the invention should not be considered limiting; the claims define the protected invention. Various changes may be made without departing from the spirit and scope of this specification and the claims. In some cases, well-known structures and techniques have not been shown or described in detail so as not to obscure the invention.

[0018] Where feasible, elements and related aspects described in detail with reference to one embodiment may be included in other embodiments where they are not specifically shown or described. For example, if an element is described in detail with reference to one embodiment but not with reference to a second embodiment, that element may still be required to be included in the second embodiment.

[0019] Figure 1 The diagram illustrates a system 100 for wireless power transmission. A wireless power transmitter 102 drives a coil 106 to generate a magnetic field. A power source 104 supplies power to the wireless power transmitter 102. The power source 104 can be, for example, a battery-based power source or can be powered by, for example, 60Hz, 120V AC power. The wireless power transmitter 102 typically drives the coil 106 within a certain frequency range according to one of the wireless power standards. However, this approach can be applied to any frequency, and it is feasible to use a magnetic coil to transmit power and / or information at any frequency, regardless of any standards that may exist.

[0020] Several standards exist for wireless power transfer, including the Wireless Power Consortium (A4WP) standard and the Wireless Power Association (WPC) Qi standard. For example, under the A4WP standard, up to 50 watts of power can be inductively transferred to multiple charging devices near coil 106 at a power transfer frequency of approximately 6.78 MHz. Under the Wireless Power Association (WPC) Qi specification, a resonant inductive coupling system is used to charge a single device at its resonant frequency. In the Qi standard, coil 108 is placed in close proximity to coil 106, while in the A4WP standard, coil 108 is placed near coil 106 along with other coils belonging to other charging devices. Figure 1 A general-purpose wireless power system 100 operating under any of these standards is depicted. In Europe, the switching frequency has been limited to 148 kHz.

[0021] like Figure 1As further shown, the magnetic field generated by coil 106 induces a current in coil 108, resulting in power being received in receiver 110. Receiver 110 receives power from coil 108 and supplies the power to load 112, which may be a battery and / or other components of a mobile device. Receiver 110 may rectify the AC signal received from coil 108 to supply a DC voltage VOUT to load 112. See, for example, the following patent documents incorporated herein by reference: U.S. Patent Publication No. US2019 / 0140489, published May 9, 2019 (inventors: Rui Liu et al.); U.S. Patent Publication No. US2018 / 0337559, published May 22, 2018 (inventors: Smith et al.); U.S. Patent Publication No. US2015 / 0115735, published April 30, 2015 (inventors: Singh et al.); U.S. Patent No. 10,601,256, published March 24, 2020 (inventors: Bakker et al.); U.S. Patent Application No. 16 / 378,273, filed April 8, 2019; and International Patent Publication No. WO 2017 / 121672, published July 20, 2017 (inventors: Staring et al.).

[0022] Transmitter 102 and receiver 110 can wirelessly communicate with each other using their coils 106 and 108 as antennas to optimize power delivery by controlling the transmitter's operating parameters as needed. Optimal power delivery may depend on the state of load 112, the physical location of the transmitter relative to the receiver, the presence of foreign objects, environmental factors, and other possible factors. For example, the optimal voltage value VOUT and optimal current value IOUT supplied to load 112 may be related to the power consumption of the mobile device. Similarly, if load 112 includes a battery, the desired output voltage value VOUT and output current value may depend on the battery type and, for a given battery, on the specific charging stage of the battery, and may vary during charging. Before charging begins, receiver 110 and transmitter 102 communicate to set transmitter operating parameters, such as the voltage amplitude and / or current amplitude and / or frequency of the power delivery signal in transmitter coil 106. When charging begins, receiver 110 periodically sends messages to transmitter 102 to adjust the transmitter operating parameters as needed.

[0023] Figure 2The illustration shows an exemplary graph depicting the relationship between the wireless power generated by the transmitting coil 106 and the coil frequency f during power transfer operation at different values ​​of the DC supply voltage VIN, where the DC supply voltage VIN defines the voltage amplitude across the transmitting coil 106. The power value is defined by the magnetic flux density B generated by the current in the coil 106. For any given input voltage VIN received from the power supply 104, and therefore for any given voltage amplitude in the coil 106, the power reaches its maximum at the resonant frequency fo of the transmitter's resonant circuit, which includes the coil 106 and possibly other components (e.g., capacitors, not shown). The maximum power operating point is shown at 210. However, to enable the transmitter to quickly correct for suboptimal and potentially dangerous power transfer conditions determined by the transmitter 102 based on messages from the receiver 110 and / or measurements from the transmitter itself, the transmitter can operate at a higher frequency f, at which the curve of B versus f has a higher negative slope, allowing the value of B to be quickly adjusted by adjusting the frequency f.

[0024] When receiver 110 requests transmitter 102 to increase or decrease the input voltage VIN (e.g., to increase VOUT or the power supplied to load 112), transmitter 102 can send a message to power supply 104 to increase or decrease the VIN voltage. When VIN increases or decreases, if the operating frequency f remains constant, the magnetic field B increases or decreases accordingly. For a fixed operating frequency f, due to a higher or lower electromotive force (EMF) applied at a fixed frequency, field B will increase or decrease and result in a higher current in Tx coil 106 (see...). Figure 2 If VIN increases, for example, decreases from V1 to V2, the direct result is that receiver 110 will experience a jump in voltage VOUT, and possibly other voltage jumps within the receiver. For example, in some embodiments, receiver 110 includes a rectifier ( Figure 7B In the rectifier (728) and voltage regulator (760), the rectifier generates a rectified DC voltage Vrect from the AC signal in coil 108; the voltage regulator (760) generates VOUT based on Vrect; see the aforementioned U.S. Patent Publication No. 2015 / 0115735. As VIN increases, Vrect and VOUT can jump proportionally to the gain of Tx / Rx coils 106 / 108, the coupling between the coils, the state of the load 112, and the magnitude (V2-V1) of the applied VIN step. In some cases, the Vrect voltage may only increase by a small amount, but in other cases (such as large VIN steps or many rapid VIN steps), the Vrect voltage may jump to very high values, potentially exceeding safe operating limits and resulting in an overvoltage condition.

[0025] To ensure safe operating ranges for Vrect, VOUT, and possibly other voltage, current, and other parameters in receiver 110, increases in VIN can be performed in small steps, with pauses between these steps to allow receiver 110 to stabilize after each step. However, this operation undesirably slows down the charging process. Furthermore, some power supplies 104 do not support small VIN steps.

[0026] Therefore, in some embodiments, the increase of VIN is coupled with an increase in the operating frequency f to shift the frequency away from the resonant frequency fo. This process limits or eliminates the increase in B as VIN increases. After VIN stabilizes to its new value, the frequency can later be reduced again or set to any desired value.

[0027] Figure 3 The appropriate process 300 is illustrated. At step 310, transmitter 102 decides to increase the voltage VIN from value V1 to a higher value V2. This decision can be made, for example, in response to a message from receiver 110. The message may command the transmitter to increase VIN, or increase VOUT, or increase the power transmitted by transmitter coil 106. The message may include new values ​​for VIN and / or VOUT and / or the transmission power, and may include other parameters, such as those that can be determined by calibration, for example, that the increase should not be done all at once, but rather in a number of steps spaced at certain time intervals; this will be discussed in more detail below.

[0028] At step 320, the transmitter increases the voltage VIN to V2 while simultaneously increasing the frequency f to limit the magnetic field B generated by the transmitting coil 106. Optionally, at step 330, after a period of time allowing the receiver to stabilize (this period can be fixed and determined by calibration at the start of the charging operation), the transmitter decreases the frequency f to a value corresponding to the desired operating power of the transmitting coil 106. If the desired operating frequency differs from the frequency at the end of step 320, step 330 is executed.

[0029] Figure 4 The illustration shows an exemplary operating point transition in steps 320 and 330. Prior to step 310, the transmitter operating point is shown as X, where VIN is at V1 and the operating frequency f is a value f1. At step 310, the transmitter has decided to move the operating point to Y, where VIN = V2, V2 is higher than V1, and f = f1. At step 320, the transmitter moves to operating point C, where VIN = V2 and the frequency f is equal to a value f2 higher than f1. In some embodiments, f2 is chosen to keep B constant, but this is not necessary: ​​the value of B can be increased or decreased, but the increase is limited by increasing the frequency f to avoid overvoltage and overcurrent in receiver 110.

[0030] At step 330, the transmitter reduces the frequency f to f1 (or another suitable value) associated with the desired operating point Y, while maintaining VIN at V2. The operating point is then shifted to Y.

[0031] Figure 5 Another implementation is shown, where step 330 precedes step 320: by keeping VIN constant at V1, but reducing the operating frequency to a value f4, the operating point first shifts from X to D. Then, by increasing the frequency (possibly back to f1) and increasing VIN to V2, the operating point shifts from D to Y. During the shift from D to Y, due to the increase in frequency, the magnetic field B remains constant or increases only slightly to limit the increase in voltage and current in the receiver.

[0032] Other transition paths from X to Y are also possible. For example, the frequency f can first be reduced to move the operating point from X along the curve VIN = V1, but not all the way to D; the input voltage VIN remains at V1. Then, the operating point can be moved from VIN = V1 to VIN = V2 while the frequency is increased to keep the magnetic field B constant or nearly constant. The frequency can then be reduced to move the operating point to Y while keeping VIN at V2. In other embodiments, VIN moves from V1 to V2 in several steps, keeping the magnetic field B constant each time due to the accompanying frequency increase; the frequency can be reduced before or after each of the one or more steps.

[0033] Figure 6 The illustration shows that Figure 5 In some embodiments of the process, the timing diagrams for voltages VIN, Vrect, and VOUT are shown as VIN changes from 12V to 14V. The VIN change occurs in five stages. Figure 5The process involves increasing VIN by 0.4 volts at each stage. Initially, the transmitter is at operating point X. For example, at time 0, all voltages VIN, Vrect, and VOUT are 12V. Then, the frequency f is decreased without changing VIN to move the operating point to D. In the illustrated embodiment, Vrect and VOUT increase from 12V (point X) to 12.4V (point D), but VIN remains at 12V. VIN then increases from 12V to 12.4V in five steps to complete the transition from D to Y. A suitable pause (e.g., 200ms) is provided between steps to allow the receiver voltage to stabilize before the next step. During each step, the frequency f increases simultaneously with VIN. Between steps, the frequency may remain constant or not. During each step, Vrect rises slightly and then falls back to its value of 12.4V before the next VIN step. During the five steps, VOUT remains constant at 12.4V. This operation is repeated to increase the three voltages from 12.4V to 12.8V, then from 12.8V to 13.2V, and so on. This example is illustrative and not limiting.

[0034] Therefore, in some embodiments, when Tx 102 receives a command from Rx 110 to increase the transmitter's output power, Tx 102 coordinates the frequency increase with the increase of VIN (because higher frequencies are further from the Tx resonant frequency): Note Figure 4 The transition from X to C, or Figure 5 The transition from D to Y. The frequency is increased to balance the B field, keeping it constant or nearly constant. During the increase of VIN, the resulting change in Vrect is small or zero. When VIN is constant or nearly constant, power can be increased by decreasing the frequency in a separate transition (e.g., Figure 4 From C to Y or Figure 5 The power balance increases from X to D. In some embodiments, this power balancing is also applied when VIN decreases (e.g., in response to a command from receiver 110 to reduce output power). The reduction of VIN is balanced by a reduction in frequency to keep the B-field flux density applied to the Rx coil constant. The VIN reduction process (e.g., reducing VIN from X to D) increases. Figure 4 Or, in step 5, V2 decreases to V1) which is the opposite of the VIN increase process. For example, this can be achieved by changing the operating point from... Figure 4 Move Y to C, then to X, or from... Figure 5 In this process, Y is moved to D, and then to X to reduce VIN.

[0035] In some embodiments, when Tx 102 receives a command from Rx 110 to change the output power, TX 102 determines one or more appropriate VIN levels for each step. The VIN change is accomplished by power supply 104 in response to the command from Tx 102. In some embodiments, power supply 104 receives AC power from a standard wall-mounted power outlet (e.g., 110V, 60Hz) and provides a DC VIN voltage. In some embodiments, power supply 104 is a travel adapter that can generate VIN from different AC voltages and / or frequencies available in different countries.

[0036] Figure 7A Some features of an embodiment of transmitter 102 are shown. (The term "transmitter" may or may not include coil 106 and power supply 104). Bridge inverter 702 (full-bridge or half-bridge inverter) generates an AC voltage from the input voltage VIN. This AC voltage is supplied to a resonant circuit including coil 106 and capacitor(s) 704 to obtain a wireless power transfer signal (WPT signal) supplied to transmitting coil 106. The WPT signal generates a magnetic field B. Processor 710 controls Tx 102 and specifically controls bridge inverter 702 (and the WPT signal frequency). Processor 710 uses memory 720 for data (e.g., including frequency and other settings) and possibly for programming the processor. Communication module 724 is used to communicate with receiver 110 and / or power supply 104. For example, module 724 may instruct processor 710 to operate the bridge inverter to superimpose a communication signal onto the WPT signal to send a message to receiver 110. In some embodiments (e.g., Qi embodiments using frequency shift keying (FSK) for transmitter messages), the communication signal does not change the amplitude of the transmitter coil voltage, but only slightly changes the operating frequency f.

[0037] PS 104 and Tx 102 can communicate via a wired link.

[0038] Figure 7BSome features of one embodiment of a mobile device with receiver 110 are shown. (The term "receiver" may or may not include coil 108). Capacitor 726 and coil 108 form a resonant circuit, which may or may not have the same resonant frequency as transmitter circuit 106 / 704. The AC current in the resonant circuit is rectified by rectifier 728. The rectifier output voltage Vrect is regulated by voltage regulator 760, which outputs voltage VOUT to load 112 via switch 764. Processor 730 controls Rx 110. Processor 730 uses memory 740 for data (e.g., including various settings) and possibly for computer instructions for programming processor 730. Communication module 744 is used to communicate with Tx 102. For example, module 744 may instruct processor 730 to modulate the impedance of the resonant circuit to send a message to Tx 102.

[0039] In some embodiments, Rx 110 and Tx 102 store the output power level in their respective memories 720. Figure 7A ), 740 Figure 7B Each memory 720, 740 includes registers for digital storage. Each processor 710, 730 may be a software and / or firmware-programmable computer processor and / or may be hardwired circuitry, possibly an FPGA (Field Programmable Gate Array) or some other electrically programmable type of circuitry. Rx 110 is connected to a host application processor (AP) 750 in a mobile device charged by transmitter 102. AP 750 may be part of load 112 and may include a processor and / or memory (not shown).

[0040] Rx 110 and Tx 102 can communicate based on any of the WPT standards referenced above or some other standards. In some embodiments, as is known in the art, Tx 102 transmits messages via FSK (Frequency Shift Keying), and Rx 110 transmits messages via ASK (Amplitude Shift Keying). The invention is not limited to FSK or ASK.

[0041] Rx 110 and Tx 102 can agree on the following: the power level sequence and / or VIN step amplitude and step sequence and / or frequency transition to be followed during the change of the transmitter's output power, and such sequence can be stored in their registers in the corresponding memories 720, 740 for power changes requested by Rx 110 autonomous operation or under the control of AP 750.

[0042] In some embodiments, before the charging operation begins, Rx 110 and Tx 102 agree on an initial output power level and record the initial power level in their respective memories 720, 740. With AP 750 involved, the initial power level agreement is reached. This initial agreement may also cover power level changes and interface processing, including power increases and VIN step size and sequence, the time interval between VIN steps, and corresponding changes in possible operating frequencies.

[0043] After each power level change, Rx 110 and Tx 102 can indicate to AP 750 when the power level change is complete, or they can operate autonomously according to their settings and programming in memory 720, 740.

[0044] The aforementioned Tx / Rx agreement can be reached before charging begins. Reaching this agreement may involve Tx 102 and Rx110 performing a learning algorithm (calibration) to determine the appropriate frequency change for each VIN step based on the transmitter output power when a power level change is initiated. This calibration can be performed in step 810, as further described below. Figure 8 ) to be executed.

[0045] In the learning algorithm, Tx 102 can perform VIN and / or frequency changes and wait for messages from Rx 110 to indicate the obtained Vrect value and / or Vrect changes, and possibly to indicate whether overvoltage or other undesirable high voltage conditions have occurred. For example, Rx 110 can send the resulting value to Tx 102 in a Control Error Packet (CEP) under the Qi standard, or in some other type of message.

[0046] Data describing VIN and frequency levels and their variations, as well as the resulting Vrect variations, can be stored as a lookup table in each memory 720, 740 (which may be non-volatile memory) during calibration. Alternatively or additionally, this data can be acquired during charging and stored as a lookup table for further reference in the same charging operation and / or subsequent charging operations. When a Vrect variation is required during charging, Rx 110 can command Tx 102 to perform the corresponding VIN and / or frequency variation. This command can specify a target VIN and / or frequency value (from the Rx 110 lookup table) and / or a target Vrect or VOUT value. Tx 102 can consult its lookup table and determine the appropriate transition (e.g., as shown in the image). Figure 4 or Figure 5 (as shown), the number of VIN steps, the timing interval between steps, and other possible parameters required to obtain a new Vrect.

[0047] Figure 8This is an exemplary flowchart of calibration and charging. At step 810, Tx 102 establishes a wireless connection with Rx 110, and as described above, calibration is performed before Rx 110 connects its VOUT terminal to load 112 (i.e., while switch 764 is still open). Before calibration begins, Tx 102 and Rx 110 may establish a target initial VOUT level according to any suitable protocol, with the participation of AP 750. For example, for the Qi protocol, the target initial VOUT level could be 5V if Tx 102 operates according to BPP (Base Power Curve), and 12V if Tx 102 operates according to EPP (Extended Power Curve). Similarly, Tx 102 and Rx 110 set initial maximum VOUT and power levels based on the type of Tx 102, the power supply capability of PS 104, and the nature of Rx 110. The capability of PS 104 is determined through communication between Tx 102 and PS 104. At step 814, Rx 110 and Tx 102, and possibly AP 750, record the established values ​​in their respective registers. Calibration is then performed as described above.

[0048] At step 818, Tx 102 and Rx 110 determine whether they both support the paper's view on... Figures 3 to 6 An embodiment of the described protocol. If not, charging is performed in step 822 as in a normal procedure, using the target initial VOUT level established at step 810.

[0049] If both Rx 110 and Tx 102 support such Figures 3 to 6 In the protocol shown, at step 826, AP 750 initiates a charging operation by writing the target VOUT into the RX 110 register. The target VOUT is established by Rx 110 to maximize its performance based on the properties of power supply 104, Tx 102, and Rx 110.

[0050] At step 830, Rx 110 sends one or more PPP (Proprietary Protocol Packets) to Tx 102 to trigger a VIN / VOUT ramp-up to raise VOUT to the appropriate value (“final VOUT voltage”) established by Rx 110 at this charging operation phase. PPP can specify the final VOUT voltage and the number of VIN steps to achieve the final VOUT. These final VOUT values ​​and the number of steps can be established during calibration at step 810.

[0051] At step 840, Tx 110 receives PPP. At step 844, Tx 110 checks PPP to determine if the final VOUT and step number are compatible with the calibration data and PS 104 capability. If not, Tx 110 sends a negative acknowledgment (NACK) to Rx 102 at step 848 (e.g., via FSK). Otherwise, Tx 110 sends a positive acknowledgment (ACK) at step 852.

[0052] At step 856, Rx 102 waits for Tx acknowledgment to reach the maximum timeout period, for example, 200 milliseconds. Then, if Rx 102 has not yet received a positive acknowledgment ACK, Rx 102 proceeds to step 822 to perform normal charging.

[0053] If Rx 110 has received a positive ACK before the timeout in step 856, then at step 864, Rx 102 increases the target VOUT by an appropriate value, such as 1V, and sends PPP to Tx 102 to trigger VIN increment. At step 868, Tx 102 receives PPP and increments VIN by the number of steps provided in step 830 (e.g., 5 steps). Each VIN increment is 200mV, and after each VIN increment, there is a predetermined pause, such as 100ms. Figure 4 or Figure 5 As shown, each increase in VIN is accompanied by an increase in frequency. Then, at step 872, Tx 102 sends an ACK to Rx 110. At step 876, Rx 102 waits for a predetermined time, for example, 600ms, for the ACK from Tx 110. If the ACK is received (step 880), the next iteration begins at step 864. Otherwise, some failure process is followed, for example, step 822 (normal charging) is performed.

[0054] This invention is not limited to the embodiments described above. Certain aspects of this invention are defined by the following provisions:

[0055] Clause 1 defines a wireless power transmitter for wireless power transfer (WPT), the transmitter comprising:

[0056] The input used to receive the WPT input signal (the WPT input signal can be, for example, VIN, or a DC signal obtained from VIN, or an AC signal);

[0057] For connection to the output of the transmitting coil;

[0058] A transmitting circuit (e.g., 102) is used to convert the WPT input signal into a WPT output signal in the transmitting coil;

[0059] The transmitting circuit is configured to increase the voltage amplitude of the WPT output signal while shifting the WPT signal frequency away from the resonant frequency of the resonant circuit including the transmitting coil. (The WPT signal may or may not include FSK or other communication signals. The WPT signal may consist only of one component of the entire signal transmitted by coil 106; the other component may be a communication signal.)

[0060] 2. The wireless power transmitter according to Clause 1, wherein when the WPT signal voltage amplitude increases, the frequency of the WPT signal moves away from the resonant frequency, reducing or eliminating the magnetic field generated by the transmitting coil and / or the energy of the magnetic field increases from the WPT signal.

[0061] 3. The wireless power transmitter according to clause 1 or 2, wherein, in response to a command from the WPT receiver, the voltage amplitude of the transmitting coil is increased while the WPT signal frequency is shifted.

[0062] 4. The wireless power transmitter according to Clause 3, wherein the transmitting circuit is further configured to, in response to a command, move the WPT signal frequency closer to the resonant frequency to increase the WPT signal power before and / or after increasing the amplitude of the transmitting coil voltage.

[0063] 5. The wireless power transmitter as described in Clause 4, wherein the amplitude of the transmitting coil voltage is kept constant as the WPT signal frequency shifts closer to the resonant frequency.

[0064] 6. The wireless power transmitter according to any one of the preceding clauses, wherein the transmitting circuit is configured to generate a WPT signal from an input signal, and increasing the amplitude of the transmitting coil voltage includes increasing the input signal voltage.

[0065] 7. The wireless power transmitter as described in Clause 6, wherein the input signal is a DC signal.

[0066] 8. A wireless power transmitter according to any one of the preceding clauses, wherein the transmitting circuitry includes a memory, and the transmitting circuitry is configured to: perform a calibration process with a wireless power receiver, the calibration process being performed when the wireless power receiver is not transmitting power to a load, the calibration process including the transmitter transmitting wireless power to the receiver in a variety of settings, wherein each setting defines a transmitting coil voltage amplitude, frequency, and one or more transitions of the transmitting coil voltage amplitude and / or frequency, and the transmitter receiving from the receiver information about how each of the settings affects the receiver voltage obtained by the receiver, and storing the settings and corresponding information in the memory;

[0067] During WPT, when the receiver transfers power to the load, the transmitter receives a command from the receiver specifying the desired value for the receiver voltage, and the transmitter executes the command based on settings information stored in memory.

[0068] 9. The wireless power transmitter as described in Clause 8, wherein at least one setting defines a time interval length following at least one transition without altering the WPT signal voltage amplitude.

[0069] 10. The wireless power transmitter as described in Clause 8, wherein during calibration, the transmitter receives from the receiver an indication for at least one setting: the setting causes an overvoltage condition in the receiver and the setting is not used in the WPT.

[0070] 11. A method for wireless power transfer (WPT), the method comprising:

[0071] The following instruction is received by the wireless power transmitter: Increase the amplitude of the transmit coil voltage of the WPT signal transmitted by the transmit coil;

[0072] In response to the instruction, the amplitude of the transmitting coil voltage is increased, and the WPT signal frequency is moved away from the resonant frequency of the resonant circuit including the transmitting coil, in order to reduce or eliminate the increase in WPT signal power associated with the increase in the transmitting coil voltage amplitude.

[0073] 12. The method according to Clause 11 further comprises: in response to an instruction, shifting the WPT signal frequency closer to the resonant frequency to increase the WPT signal power before or after increasing the amplitude of the transmitting coil voltage.

[0074] 13. The method according to clause 11 or 12, wherein the amplitude of the transmitting coil voltage is kept constant as the WPT signal frequency shifts close to the resonant frequency.

[0075] 14. The method according to any one or more of clauses 11 to 13, wherein the transmitter generates a WPT signal from an input signal, and increasing the amplitude of the transmitting coil voltage includes: increasing the input signal voltage.

[0076] 15. The method according to Clause 14, wherein the input signal is a DC signal.

[0077] 16. The method according to any one or more of clauses 11 to 15, wherein the transmitting circuitry includes a memory and is configured to perform a calibration process with a wireless power receiver, the calibration process being performed when the wireless power receiver is not transmitting power to a load, the calibration process comprising: the transmitter transmitting wireless power to the receiver in a plurality of settings, each setting defining a transmitting coil voltage amplitude, frequency, and one or more transitions of the transmitting coil voltage amplitude and / or frequency, and the transmitter receiving from the receiver information about how each of the settings affects the receiver voltage obtained by the receiver, and storing the settings and corresponding information in the memory;

[0078] During WPT, when the receiver transfers power to the load, the transmitter receives a command from the receiver specifying the desired value of the receiver voltage, and the transmitter executes the command based on information stored in memory for the specified settings.

[0079] 17. The wireless power transmitter as described in Clause 16, wherein at least one setting defines a time interval length following at least one transition without altering the WPT signal voltage amplitude.

[0080] 18. A wireless power receiver, comprising:

[0081] Input for connection to the transmitting coil;

[0082] The output used to connect to the load; and

[0083] The receiving circuit is used to convert the WPT input signal in the receiving coil to provide power to the load;

[0084] The receiving circuitry includes a memory and is configured to perform a calibration process with a wireless power transmitter. The calibration process is performed when the wireless power receiver is not transmitting power to a load. The calibration process includes: receiving wireless power from the wireless power transmitter in a receiving coil at multiple settings, each setting defining the transmit coil voltage amplitude, WPT input signal frequency, and one or more transitions in the transmit coil voltage amplitude and / or frequency; and the receiver sending information to the transmitter about how each of the settings affects the receiver voltage obtained by the receiver, and storing the settings and corresponding information in the memory.

[0085] During WPT, when the receiver transfers power to the load, the receiver sends a command to the transmitter specifying the desired value for the receiver voltage.

[0086] 19. The wireless power receiver as described in Clause 18, wherein at least one setting defines a time interval length following at least one transition without altering the WPT signal voltage amplitude.

[0087] 20. A wireless power receiver as described in Clause 18 or 19, wherein during calibration, the receiver determines information about whether at least one setting results in excessive voltage in the receiver and transmits the information to the transmitter.

[0088] The above detailed description is provided to illustrate specific embodiments of the invention and is not intended to be limiting. Many variations and modifications are possible within the scope of the invention. The invention is set forth in the appended claims.

Claims

1. A wireless power transmitter for wireless power transfer (WPT), the transmitter comprising: Input used to receive WPT input signals; For connection to the output of the transmitting coil; A transmitting circuit is used to convert the WPT input signal into a WPT output signal in the transmitting coil. The transmitting circuit includes a processor and an inverter. The inverter is used to generate the WPT output signal from the WPT input signal under the control of the processor. The transmitting circuit is configured as follows: It is determined that the power of the WPT output signal needs to be increased, such that increasing the power of the WPT output signal includes increasing the voltage amplitude of the WPT output signal; and In response to the determination, the increase in the voltage amplitude of the WPT output signal is coordinated with the change in the frequency of the WPT output signal, so as to increase the voltage amplitude of the WPT output signal while operating the inverter to shift the frequency of the WPT output signal away from the resonant frequency of the resonant circuit including the transmitting coil.

2. The wireless power transmitter according to claim 1, wherein when the voltage amplitude of the WPT output signal increases, shifting the frequency of the WPT output signal away from the resonant frequency reduces or eliminates the increase in the magnetic field generated by the transmitting coil and / or the energy of the magnetic field from the WPT output signal.

3. The wireless power transmitter of claim 1, wherein, in response to a command from the WPT receiver, the voltage amplitude of the WPT output signal is increased while simultaneously shifting the frequency of the WPT output signal.

4. The wireless power transmitter of claim 3, wherein the transmitting circuit is further configured to: in response to the command, before or after increasing the voltage amplitude, move the frequency of the WPT output signal closer to the resonant frequency to increase the power of the WPT output signal.

5. The wireless power transmitter according to claim 4, wherein the voltage amplitude of the WPT output signal is kept constant when the frequency of the WPT output signal shifts closer to the resonant frequency.

6. The wireless power transmitter according to claim 1, wherein increasing the voltage amplitude of the WPT output signal includes increasing the voltage of the WPT input signal.

7. The wireless power transmitter according to claim 6, wherein the WPT input signal is a DC signal.

8. The wireless power transmitter of claim 1, wherein the transmitting circuitry includes a memory, and the transmitting circuitry is configured to: perform a calibration process with a wireless power receiver, the calibration process being performed when the wireless power receiver is not transmitting power to a load, the calibration process comprising: The transmitter transmits wireless power to the receiver in a variety of settings, wherein each setting defines the voltage amplitude of the WPT output signal, the frequency, and one or more transitions of the voltage amplitude and / or frequency of the WPT output signal, and the transmitter receives from the receiver information about how each of the settings affects the receiver voltage obtained by the receiver, and stores the settings and corresponding information in the memory; During the WPT, when the receiver transfers power to the load, the transmitter receives a command from the receiver specifying a desired value for the receiver voltage, and the transmitter executes the command based on information stored in the memory for the settings.

9. The wireless power transmitter of claim 8, wherein at least one setting defines a time interval length for following at least one transition without changing the voltage amplitude of the WPT output signal.

10. The wireless power transmitter of claim 8, wherein during the calibration process, the transmitter receives from the receiver an indication of at least one setting: the setting causes an overvoltage condition in the receiver, and the setting is not used in the WPT.

11. The wireless power transmitter of claim 10, wherein at least one setting defines a time interval length following the transition for at least one transition without changing the voltage amplitude of the WPT output signal.

12. A method for wireless power transfer (WPT), the method comprising: The wireless power transmitter according to claim 1 receives the following instruction: increase the voltage amplitude of the signal output by the WPT; In response to the instruction, the WPT voltage amplitude is increased, and the frequency of the WPT output signal is shifted away from the resonant frequency of the resonant circuit including the transmitting coil, in order to reduce or eliminate the power increase of the WPT output signal associated with the increase in the voltage amplitude.

13. The method of claim 12, further comprising: In response to the instruction, before or after increasing the voltage amplitude, the frequency of the WPT output signal is moved closer to the resonant frequency to increase the power of the WPT output signal.

14. The method of claim 12, wherein the voltage amplitude is kept constant as the frequency of the WPT output signal shifts closer to the resonant frequency.

15. The method of claim 12, wherein the transmitter generates the WPT output signal from the input signal, and increasing the voltage amplitude comprises: Increase the input signal voltage of the WPT.

16. The method of claim 15, wherein the input signal is a DC signal.

17. The method of claim 12, wherein the transmitting circuitry includes a memory and is configured to perform a calibration process with a wireless power receiver, the calibration process being performed when the wireless power receiver is not transmitting power to a load, the calibration process comprising: The transmitter transmits wireless power to the receiver in a variety of settings, each setting defining the voltage amplitude, the frequency, and one or more transitions of the voltage amplitude and / or frequency, and the transmitter receives information from the receiver about how each of the settings affects the receiver voltage obtained by the receiver, and stores the settings and corresponding information in the memory; During the WPT, when the receiver transfers power to the load, the transmitter receives a command from the receiver specifying a desired value for the receiver voltage, and the transmitter executes the command based on information stored in the memory for the settings.

18. A wireless power receiver, comprising: Input for connection to the transmitting coil; The output used to connect to the load; as well as A receiving circuit is used to convert the WPT input signal in the receiving coil to provide power to the load; The receiving circuitry includes a memory and is configured to perform a calibration process with a wireless power transmitter, the calibration process being performed when the wireless power receiver is not transmitting power to the load. The calibration process includes: receiving wireless power from the wireless power transmitter in the receiving coil at various settings, each setting defining a transmit coil voltage amplitude, a WPT input signal frequency, and one or more transitions in the transmit coil voltage amplitude and / or frequency; the receiver sending information to the transmitter about how each of the settings affects the receiver voltage obtained by the receiver; and storing the settings and corresponding information in the memory. During the WPT, when the receiver transfers power to the load, the receiver sends a command to the transmitter specifying the desired value of the receiver voltage.

19. The wireless power receiver of claim 18, wherein at least one setting defines a time interval length following the transition for at least one transition without changing the voltage amplitude of the WPT output signal.

20. The wireless power receiver of claim 18, wherein during the calibration process, the receiver determines information regarding whether at least one setting results in excessive voltage in the receiver, and transmits the information to the transmitter.

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