Methods and devices for wireless charging

Abstract

Embodiments of this disclosure relate to methods and apparatus for wireless charging. A method for modulating a signal includes: operating circuitry in a first arrangement during a first operating interval; and switching the circuitry between the first arrangement and a second arrangement during the first modulation interval to change the load on the circuitry to generate a first amplitude shift keying (ASK) signal. The method further includes: detecting a voltage on the circuitry that exceeds a threshold level; and operating circuitry in a second arrangement during a second operating interval. The method further includes switching the circuitry between the second arrangement and the first arrangement during the second modulation interval to change the load on the circuitry to generate a second ASK signal.

Description

Technical Field

[0001] This invention relates to methods and apparatus for wireless charging. Background Technology

[0002] Wireless charging is becoming a preferred method for charging many electronic devices, including but not limited to mobile phones, smartwatches, and tablets. The power receiving device is wirelessly coupled to the power transmitting device. During power transmission, communication between the power receiving and transmitting devices may be required. Communication can be achieved by changing the load on the receiving circuitry of the power receiving device to generate an amplitude shift keying (ASK) signal. However, this may increase the voltage of the receiving circuitry to an undesirable high level or decrease it to an undesirable low level. Summary of the Invention

[0003] According to an embodiment of the present invention, a method for modulating a signal includes: operating a circuit in a first arrangement during a first operating interval, and switching the circuit between the first arrangement and a second arrangement during the first modulation interval to change the load on the circuit to generate a first amplitude shift keying (ASK) signal. The method may further include: detecting a voltage on the circuit that exceeds a threshold level; operating a circuit in a second arrangement during a second operating interval; and switching the circuit between the second arrangement and the first arrangement during the second modulation interval to change the load on the circuit to generate a second ASK signal.

[0004] According to an embodiment of the present invention, a method for modulating a signal includes: operating a circuit in a first arrangement during a first operating interval; and switching the circuit between the first arrangement and a second arrangement during the first modulation interval to change the load on the circuit to generate a first amplitude shift keying (ASK) signal, wherein switching the circuit from the first arrangement to the second arrangement increases the voltage across the load on the circuit. The method further includes: detecting a voltage on the circuit exceeding a threshold level; operating a circuit in a second arrangement during a second operating interval; and switching the circuit between the second arrangement and the first arrangement during the second modulation interval to change the load on the circuit to generate a second ASK signal, wherein switching the circuit from the second arrangement to the first arrangement decreases the voltage across the load on the circuit.

[0005] According to an embodiment of the present invention, a method for modulating a signal includes: operating a circuit in a first arrangement during a first operating interval; and switching the circuit between the first arrangement and a second arrangement during the first modulation interval to change the load on the circuit to generate a first amplitude shift keying (ASK) signal, wherein switching the circuit from the first arrangement to the second arrangement reduces the voltage across the load on the circuit. The method further includes: detecting a voltage on the circuit that has dropped below a threshold level; operating a circuit in a second arrangement during a second operating interval; and switching the circuit between the second arrangement and the first arrangement during the second modulation interval to change the load on the circuit to generate a second ASK signal, wherein switching the circuit from the second arrangement to the first arrangement increases the voltage across the load on the circuit.

[0006] According to an embodiment of the present invention, a system for wirelessly transmitting power from a power transmitting device to a power receiving device includes: a power transmitting device including a transmitting circuit configured to be coupled to a power source. The system further includes a power receiving device including a receiving circuit configured to wirelessly receive power from the power transmitting device; and a modulator including an output coupled to a control gate of a switch, wherein the modulator is configured to deliver a control signal to the control gate to alternately switch between an open state and a closed state to couple or decouple a capacitor from the receiving circuit. The modulator is configured to operate the switch during a modulation interval to change the load on the receiving circuit to generate an amplitude shift keying (ASK) signal; and to maintain the switch in a default state during the operation interval, the default state including either an open state or a closed state. The system may further include a processor communicating with the modulator, and the processor is configured to execute a set of instructions stored in a non-transitory computer-readable medium to instruct the modulator to transition the default state to the other state, either an open state or a closed state, when the receiving circuit wirelessly receives power. Attached Figure Description

[0007] Now, with reference to the accompanying drawings, one or more embodiments will be described by way of example only, wherein

[0008] Figure 1 A system for wirelessly charging devices is described;

[0009] Figure 2 A block diagram depicting the components of the power receiving device;

[0010] Figure 3 A system for wirelessly charging a device configured as a modulated load to generate an ASK signal is described.

[0011] Figure 4The components for modulating signals via a power receiving device are described;

[0012] Figure 5 The waveforms of the voltage across the load in the receiving circuit during the modulation period are depicted.

[0013] Figure 6 The waveforms of the voltage across the load in the receiving circuit during the modulation period are depicted.

[0014] Figure 7a depicts the modulated signal according to the differential biphase coding scheme;

[0015] Figure 7B The modulated signal according to the differential biphase coding scheme is described;

[0016] Figure 8 A block diagram of a system for avoiding unwanted high and low voltages in the receiving circuit is depicted.

[0017] Figure 9 The waveforms before and after the default state transition of one or more switches are shown;

[0018] Figure 10 The waveforms before and after the default state transition of one or more switches are shown;

[0019] Figure 11 This is a flowchart illustrating methods for avoiding unwanted high or low voltages during wireless transmission;

[0020] Figure 12 A method for modulating signals is described;

[0021] Figure 13 A method for modulating signals is described;

[0022] Figure 14 A method for modulating signals is described; Detailed Implementation

[0023] In the following description, one or more specific details are set forth to provide a thorough understanding of examples of embodiments of this specification. Embodiments may be obtained without one or more of these specific details, or by utilizing other methods, components, materials, etc. In other instances, known structures, materials, or operations have not been described in detail so as not to obscure certain aspects of the embodiments.

[0024] References to "an embodiment" or "one embodiment" within the framework of this specification are intended to indicate that a particular configuration, structure, or feature described with respect to that embodiment is included in at least one embodiment. Therefore, phrases such as "in one embodiment" or "in one embodiment" appearing at one or more points in this specification do not necessarily refer to one and the same embodiment. Furthermore, in one or more embodiments, particular conformations, structures, or features may be combined in any suitable manner.

[0025] Figure 1 A system 100 for wirelessly charging devices is described.

[0026] As in Figure 1 As shown, system 100 may include a power transmitting device 102 and a power receiving device 108. The power transmitting device 102 may include an inductor coil 104. And the power receiving device may include an inductor coil 110.

[0027] The power transmitting device 102 can be configured to couple to a power source via a plug 106. In various embodiments, the plug 106 can be configured to mate with a wall socket. In various embodiments, the power transmitting device 102 may include a battery that can be used as a power source for wirelessly transmitting power from the power transmitting device 102 to the power receiving device 108.

[0028] The power source can generate alternating current in the power transmitting device 102 via inductor coil 104. This will create an oscillating magnetic field and induce current in the receiving circuit (at least referring to...). Figure 3 (To be described in more detail). Then, in various embodiments, the battery 109 of the power receiving device 108 can be charged using the current induced in the power receiving device 108 by the oscillating magnetic field.

[0029] The current received by the power receiving device 108 may include alternating current (AC). In various embodiments, it may be advantageous to convert the AC received by the power receiving device 108 into direct current (DC). This is advantageous because many electronic components are compatible with DC. A voltage regulator may also be used to reduce the voltage level of the supplied power to a level compatible with the components of the power receiving device 108.

[0030] Figure 2 Block diagrams depicting the components of the power receiving device 108 in various embodiments are shown. For example... Figure 2 As shown, current can be inducted in the receiving circuit 202. The alternating current can then be directed to the rectifier 204. In various embodiments, the rectifier may include a full-bridge rectifier. The rectifier 204 may be coupled to a voltage regulator 206. The voltage regulator 206 may include a buck regulator to reduce the voltage.

[0031] Communication between the power transmitting device 102 and the power receiving device 108 can facilitate the establishment of coupling and the regulation of power delivery. In various embodiments, the power receiving device 108 can communicate to request more or less power from the power transmitting device 102.

[0032] Communication between the power transmitting device 102 and the power receiving device 108 can be achieved via amplitude shift keying (ASK) signals. The Wireless Power Consortium (WPC) provides the Qi standard for wireless power transmission. Furthermore, according to the Qi standard, amplitude shift keying can be used for communication between the power transmitting device 102 and the power receiving device 108.

[0033] Amplitude Shift Keying (ASK) is a form of modulation signal in which variations in the signal amplitude are used to transmit data. In various embodiments, the power receiving device 108 can generate an ASK signal by changing the load on the receiving circuitry.

[0034] Figure 3 A system 300 for wirelessly charging a device configured as a modulated load to generate an ASK signal is described.

[0035] System 300 for wirelessly charging devices may include a power transmitting device 102 and a power receiving device 108. The power transmitting device 102 may include a transmitting circuit 301. The transmitting circuit 301 may include a power source 302. The transmitting circuit 301 may also include an inductor 104 and a capacitor 304.

[0036] System 300 may also include a power receiving device 108. Power receiving device 108 ( Figure 3 (Not shown) may include a receiving circuit 303. The receiving circuit 303 may include an inductor 110, a capacitor 310, and a capacitor 312. The receiving circuit 303 may include a capacitor 312 to implement a dual resonant circuit.

[0037] In various embodiments, when the power transmitting device 102 and the power receiving device 108 are arranged such that the inductor coil 104 of the transmitting circuit 301 and the inductor coil 110 of the receiving circuit 303 are close to each other, they form an air-core transformer. The power source 302 in the transmitting circuit 301 can provide alternating current through the transmitting circuit and the inductor coil 110. This can generate an oscillating magnetic field. When the power receiving device 108 is within range of the power transmitting device 102, the oscillating magnetic field generated by the transmitting circuit 301 can induce a current in the receiving circuit 303. This allows the receiving circuit 303 to wirelessly receive power from the transmitting circuit 301 of the power transmitting device 102. It should be noted that in various embodiments, the ground in the transmitting circuit 301 and the ground in the receiving circuit are not a common ground.

[0038] In various embodiments, the receiving circuit 303 may further include a rectifier 204 to rectify the alternating current inducted in the receiving circuit 303.

[0039] The receiving circuit 303 may also include a modulation capacitor 316. The load at the output of the receiving circuit 303 may be represented by a load 320. However, this can be varied by coupling or decoupling the modulation capacitor 316 from the receiving circuit 303 via a first switch 318. Preferably, a capacitor, rather than a resistor, is used to vary the load on the receiving circuit 303 because the charge stored in the capacitor can be reintroduced into the receiving circuit without being wasted. In various embodiments, the first switch 318 may include a MOSFET. In various embodiments, the first switch 318 may also include any number of other switches known in the art.

[0040] Those skilled in the art will understand that the first switch 318 can have an open state and a closed state. When the first switch 318 is in the closed state, the modulation capacitor 316 can be coupled to the transmitting circuit 301. When the first switch 318 is in the open state, the modulation capacitor 316 can be decoupled from the transmitting circuit 301. The transmitting circuit 301 may also include an additional modulation capacitor and a corresponding switch, which can also be coupled to the receiving circuit 303. In various embodiments, when the additional modulation capacitor and the corresponding switch are coupled to the receiving circuit 303, the additional modulation capacitor and the corresponding switch can be connected in parallel with each other.

[0041] Coupling and decoupling the modulation capacitor 316 into the receiving circuit can alter the system response and the gain of the receiving circuit 303. This will also cause a change in the total load of the receiving circuit 303. Therefore, by opening and closing the first switch 318, the total load of the circuit can be changed to generate an ASK modulated signal.

[0042] The effects of coupling and decoupling of modulation capacitor 316 on the system response can vary depending on the switching frequency of the alternating magnetic field. For example, assuming other factors that can change the system response remain constant, when the frequency is above the inflection point, coupling modulation capacitor 316 can decrease the gain of receiving circuit 303. Then, when the frequency is above the inflection point, decoupling modulation capacitor 316 can increase the gain of receiving circuit 303. When the frequency is below the inflection point, coupling modulation capacitor 316 can increase the gain of receiving circuit 303. Then, when the frequency is below the inflection point, decoupling modulation capacitor 316 can decrease the gain of receiving circuit 303. Other factors that can change the system response may include the alignment and distance between power transmitting device 102 and power receiving device 108 or the load.

[0043] By way of further example, if there is an inflection point at a frequency of 125 kHz, coupling the modulation capacitor 316 to the receiving circuit 303 at frequencies below 125 kHz increases the gain of the receiving circuit 303, while coupling the modulation capacitor 316 to the receiving circuit 303 at frequencies above 125 kHz decreases the gain of the receiving circuit 303. Therefore, decoupling the modulation capacitor 316 from the receiving circuit 303 at frequencies below 125 kHz will decrease the gain, while decoupling the modulation capacitor 316 from the receiving circuit 303 at frequencies above 125 kHz will increase the gain. The frequency of the inflection point can vary in different embodiments.

[0044] By coupling and decoupling the modulation capacitor 316 from the receiving circuit 303, the load on the receiving circuit 303 can be varied by alternating between a first arrangement and a second arrangement. In various embodiments, the receiving circuit 303 can be in the first arrangement when the modulation capacitor 316 is coupled to it. Furthermore, the receiving circuit 303 can be in the second arrangement when the modulation capacitor 316 is decoupled from it.

[0045] In various embodiments, the receiving circuit 303 can be in a first arrangement when the modulation capacitor 316 is decoupled from the receiving circuit 303. Furthermore, the receiving circuit 303 can be in a second arrangement when the modulation capacitor 316 is coupled to the receiving circuit 303. These arrangements can vary depending on the parameters of the power transfer and switching frequencies.

[0046] The operation of the first switch 318 can be controlled by a modulator coupled to the first switch 318.

[0047] Figure 4 The components used for modulating signals via a power receiving device are described.

[0048] like Figure 4 As shown, system 300 may include a first switch 318 and a second switch 319. Figure 4 Modulator 404 and processor 406 are also depicted. Figure 3 Not described in, but Figure 4 The components depicted can be integrated into Figure 3 In the architecture shown.

[0049] The first switch 318 may include a MOSFET, and the second switch 319 may also include a MOSFET. The control gate of the first switch 318 may be coupled to the first output 404A of the modulator 404. The control gate of the second switch 319 may also be coupled to the second output 404B of the modulator 404. Furthermore, in various embodiments, the modulator 404 may communicate with the processor 406.

[0050] Modulator 404 can be configured to deliver a control signal to the control gate of first switch 318, causing first switch 318 to alternate between an open and closed state. This can modulate capacitor 316 (such as...) Figure 3 (As shown) is coupled and decoupled from the receiving circuit 303.

[0051] As mentioned above, the receiving circuit 303 may further include an additional modulation capacitor, which can be coupled and decoupled from the receiving circuit 303 via an additional switch. The second switch 319 may include a switch for switching the second modulation capacitor ( Figure 3 (Not shown in the image) is coupled and decoupled from the receiving circuit 303.

[0052] Modulator 404 can be configured to deliver a control signal to the control gate of second switch 319, causing second switch 319 to alternate between an open and closed state. This can activate the second modulation capacitor ( Figure 3 (Not shown in the image) is coupled and decoupled from the receiving circuit 303.

[0053] In various embodiments, the first switch 318 and the second switch can be operated simultaneously. Both the first switch 318 and the second switch 319 can be simultaneously opened or closed. In various embodiments, a signal from the output can operate both the first switch 318 and the second switch 319.

[0054] The additional modulation capacitor can be coupled and decoupled from the receiving circuit 303 via an additional switch. In various embodiments, the operation of the additional switch can also be controlled by the modulator 404.

[0055] A change in the load on the receiving circuit 303 will affect the voltage across the load terminals of the receiving circuit 303. The power transmitting device 102 can sense these changes and demodulate the signal.

[0056] Figure 5 The waveform depicts the voltage across the load of the receiving circuit during the modulation period.

[0057] Figure 5 The waveform of the voltage across the load of the receiving circuit 303 is shown when the modulation capacitor 316 is coupled and decoupled from the receiving circuit 303. (As shown in...) Figure 3 As shown in the diagram, in various embodiments, the voltage across the load may include the voltage between the first node 204A and the second node 204B. Return to Figure 5During the first operating interval 501, while the power transmitting device 102 is transmitting power to the power receiving device 108, the voltage across the load may be at or substantially at level V1. During the first modulation interval 502, the modulator 404 may operate the first switch 318 and any additional switches to couple and decouple the modulation capacitor 316 and any additional capacitors from the receiving circuit 303, causing a change in the voltage across the load. In various embodiments, this can increase or decrease the voltage across the load between V1 and V2. Figure 5 As shown, V2 is higher than V1.

[0058] During the second operating interval 503, the receiving circuit 303 can continue to receive power from the power transmitting device 102, and the voltage of the receiving circuit 303 can be maintained at V1. During the second modulation interval 504, modulation can be performed again. And, this process can be repeated whenever needed.

[0059] Modulation can also be achieved by reducing the voltage across the load instead of increasing it.

[0060] Figure 6 The waveform depicts the voltage across the load of the receiving circuit during the modulation period.

[0061] Figure 6 The waveform of the voltage across the load of the receiving circuit 303 is shown when the modulation capacitor 316 is coupled and decoupled from the receiving circuit 303. During the first operating interval 601, when the power transmitting device 102 is transmitting power to the power receiving device 108, the voltage across the load may be at or substantially at level V1. Figure 5 The waveforms depicted are very similar. During the first modulation interval 602, modulator 404 can operate the first switch 318 and any additional switches to couple and decouple the modulation capacitor 316 and any additional capacitors from the receiving circuit 303, causing a change in the voltage across the load. In various embodiments, this can increase and decrease the voltage across the load between V1 and V2. However, as... Figure 6 As shown, V2 can be lower than V1.

[0062] Again, with Figure 5 Similar to the waveform depicted, during the second operating interval 603, the receiving circuit 303 can continue to receive power from the power transmitting device 102, and the voltage of the receiving circuit 303 can be maintained at V1. Modulation can be performed again during the second modulation interval 604. Furthermore, this process can be repeated whenever necessary.

[0063] In various embodiments, the receiving circuit will continue to receive power during the modulation interval. In various embodiments, the voltage level may fluctuate during the operating interval. In fact, through modulation, communication between the power receiving device 108 and the power transmitting device 102 can cause the power transmitting device 102 to decrease or increase its power transmission level, thereby increasing or decreasing the voltage level during the operating period. In various embodiments, the modulation interval may occur at a preset time. In various embodiments, the modulation interval may occur as needed. It should also be understood that, as described above, the arrangement required to increase the voltage across the load of the receiving circuit 303 can vary depending on the switching frequency.

[0064] In various embodiments, modulator 404 may be configured to operate modulation capacitor 316 and additional switches (if present) to change the load of the receiving circuit according to the differential biphase coding scheme for the ASK signal.

[0065] Figure 7a depicts the modulated signal according to the differential biphase coding scheme.

[0066] For differential biphase coding schemes, time periods can correspond to data bits. Figure 7A A first time period 702A, a second time period 704A, and a third time period 706A are depicted. The number of transitions from one voltage level to another (in the ASK signal) determines the bit value of the time period. For example, a "1" can be represented by a time period during which there is a transition from one voltage level. And a "0" can be represented by a time period during which there is no transition. In this scheme, the first time period 702A can correspond to "1", the second time period 704A can correspond to "0", and the third time period 706A can also correspond to "0". It should be understood that the bit values ​​attached to the signal can also be inverted, such that time periods with transitions correspond to "0", and time periods without transitions correspond to "1". In various embodiments, the time periods can correspond to clock periods. Transitions between voltage levels can be caused by the coupling or decoupling of the modulation capacitor 316 and any additional modulation capacitors (if present). Figure 7A As depicted, V2 is greater than V1. Depending on the switching frequency, the voltage increase can be caused by coupling the modulation capacitor 316 and any additional modulation capacitor, or by decoupling the modulation capacitor 316 and any additional modulation capacitor.

[0067] Figure 7B The modulated signal according to the differential biphase coding scheme is described.

[0068] and Figure 7A similar, Figure 7BThe first time period 702B, the second time period 704B, and the third time period 706B are depicted. (See reference...) Figure 7A As described, (in the ASK signal) the number of transitions from one voltage level to another can again determine the bit value for that time period. However, in Figure 7B In this case, V2 is lower than V1. Nevertheless, in Figure 7B The waveform in the image can also convey... Figure 7A The same bit sequence is used because the corresponding time periods have the same number of transitions. Depending on the switching frequency, reducing the voltage from V1 to V2 can be caused by coupling the modulation capacitor 316 and any additional modulation capacitor, or by decoupling the modulation capacitor 316 and any additional modulation capacitor.

[0069] In various embodiments, the default states of the first switch 318 and any other switches, such as the second switch 319, can be determined for power transfer between the power transmitting device 102 and the power receiving device 108. This can occur after coupling between the power transmitting device 102 and the power receiving device 108, but before power is transmitted to the battery of the power receiving device 108. Transmission between the power transmitting device 102 and the power receiving device 108 can be used to establish an initial power transmission level and the default states of the first switch 318 and any other switches, such as the second switch 319. In various embodiments, it is preferred that the first switch 318 and any additional switches, such as the second switch 319, can be disconnected to prevent energy loss stored in the modulation capacitor 318. The default state of the switches can be open or closed. The first switch 318 and any additional switches, such as the second switch 319, can be in the default state during operating intervals and can alternate between the default state and a relative state during modulation intervals to change the load on the receiving circuit.

[0070] For example, if the first switch 318 and any additional switches, such as the second switch 319, are open in the default state, the modulation capacitor 316 and any additional modulation capacitors are decoupled from the receiving circuit 303 in the default state. The modulator can be configured to maintain the default state and keep the modulation capacitor 316 and any additional modulation capacitors decoupled during the operating interval, so that the load will not change significantly. During the modulation interval, the modulator can be configured to operate the switches to switch between an open state (the default state in this example) and a closed state to allow the load to change and the signal to be modulated.

[0071] When the first switch 318 and any additional switches such as the second switch 319 are closed in the default state, the modulation capacitor 316 and any additional modulation capacitors are coupled to the receiving circuit 303 during the operating interval.

[0072] The default state of the first switch 318 and any additional switches such as the second switch 319 can determine whether the modulation causes the voltage to be in the positive direction (e.g., Figure 5 and Figure 7A The deflection described is either in the negative direction or in the negative direction (e.g.) Figure 6 and Figure 7B The offset (as depicted) is used to encode information. For example, for a given frequency, where the coupling modulation capacitor 316 and any additional modulation capacitors increase the voltage across the load of the receiving circuit 303, the default open setting of the first switch and any additional switches allows the modulation to increase the voltage above the level depicted. Figure 5 and Figure 7A The voltage seen during the depicted operating interval. For this example, the default closed setting for the first switch 318 and any other switch such as the second switch 319 allows modulation to reduce the voltage below the level seen during the operation. Figure 6 and Figure 7B The voltage seen during the operating interval.

[0073] For a given frequency, where the coupling modulation capacitor 316 and any additional modulation capacitors reduce the voltage across the load of the receiving circuit 303, the disconnected default state allows the voltage to be reduced below the level at which the frequency is lower than the threshold frequency. Figure 6 and Figure 7B The voltage seen during the operation period is modulated. For this example, the default closed setting for the first switch 318 and any additional switches such as the second switch 319 allows the modulation to increase the voltage above the specified level. Figure 5 and Figure 7A The voltage observed during the depicted operating interval.

[0074] It should be understood that different devices may prefer different voltage levels for power transmission. For example, a power receiving device 108 with a larger battery (such as a tablet computer) may prefer a higher voltage. A power receiving device 108 with a smaller battery (such as a smartwatch) may prefer a lower voltage.

[0075] In various embodiments, if the voltage becomes too high or too low, the increase or decrease in voltage across the load of the receiving circuit 303 can lead to undesirable results. (See again...) Figure 5 If the voltage at V2 becomes too high, it may damage components of the power receiving device 108. This can also cause the power receiving device 108 to communicate with the power transmitting device 102 to reduce the voltage level during operation, which can slow the transfer of power from the power transmitting device 102 to the power receiving device 108. In various embodiments, this can increase the time required to charge the battery.

[0076] Now, for reference Figure 6 The voltage at V2 can become lower than expected. This is undesirable because a low voltage can trigger undervoltage lockout (UVLO) and cause the power receiving device 108 to reset.

[0077] Figure 8 A block diagram of a system 800 is depicted to avoid unwanted high voltages and unwanted low voltages in the receiving circuit.

[0078] System 800 may combine rectifier 204, processor 406, and modulator 404. The modulator may deliver control signals to first switch 318, second switch 319, and any additional switches to change the load on receiving circuit 303 to modulate the signal. The modulator may maintain first switch 318, second switch 319, and any additional switches in their default states (regardless of whether the default state is open or closed) during non-modulation operation intervals. Processor 406 may communicate with modulator 404 and may execute a set of instructions stored in non-transitory computer-readable medium 804 to instruct modulator 404 to transition from the default state to a relative state. This may occur while receiving circuit 303 is receiving power without interrupting power transfer between power transmitting device 102 and power receiving device 108. For example, if the default state is open, transitioning the default state to a relative state will cause the default state to be closed. As a result, this will cause the polarity of the voltage shift occurring during modulation to change from positive (e.g., ...) depending on the frequency of the circuit. Figure 5 and Figure 7A The depicted) inversion is negative (such as) Figure 6 and Figure 7B (As depicted), or reversed from negative to positive. If the default state is closed, changing the default state to a relative state will make the default state appear open. This is advantageous because the default setting can be switched if the modulation pushes the voltage across the load of the receiving circuit 303 too high or too low. Furthermore, this can be done during ongoing power transfer.

[0079] In various embodiments, the system may further include an analog-to-digital converter 802. The analog-to-digital converter 802 can convert the voltage level across the load of the receiving circuit into a digital signal. The processor 406 can receive the digital signal. When the voltage level at the load exceeds a threshold level, or drops below a threshold level, the processor can be triggered to instruct the modulator to switch to a default state. Figure 8 The components described herein can be integrated into Figure 3 and Figure 4 In the architecture shown.

[0080] Figure 9 The waveforms are shown before and after the default state of one or more switches in the receiving circuit is changed.

[0081] exist Figure 9 The waveform depicts the magnitude of the voltage variation across the load of circuit 303 when the power transmitting device 102 is coupled to the power receiving device 108 to transmit power. Figure 9 Multiple modulation intervals, such as 902, and multiple operation intervals, such as 904, are described. Before time T1, the voltage across the load of the receiving circuit 303 is V. 01 With V hi The voltage changes between these intervals to modulate the signal. Before time T1, the voltage remains at V during the operating interval. 01 Place or V 01 Nearby. At time T1, the default states of the first switch 318 and any additional switches, such as the second switch 319, are converted to relative states. For example, if the default state before T1 is open, the default state after T1 is closed. If the default state before T1 is closed, the default state after T1 is open. Figure 9 As described in the text, after the default value is converted, the voltage will be at V during the modulation interval. 02 With V lo The values ​​change between and remain at V during the operation interval. 02 The default state transition allows system 300 to reverse the modulation polarity from an increase in voltage (before T1) to a decrease in voltage (after T1). Therefore, undesirable high voltages across the load of circuit 303 can be avoided, and the voltage level can be maintained or even increased during the operating interval. Furthermore, in various embodiments, the default state transition can occur without interrupting the ongoing power transfer from power transmitting device 102 to power receiving device 108.

[0082] After the default state is switched at T1, the voltage across the load of the receiving circuit 303 may temporarily increase in some cases during the operation interval. This could be due to the circuit 303 switching from a low-gain default state to a high-gain default state. However, the power transmitting device 102 can receive a modulated signal and adjust the oscillating magnetic field according to the modulated signal so that the voltage level is reduced until it reaches V. 02 .

[0083] Figure 10 The waveforms are shown before and after the default state of one or more switches in the receiving circuit is changed.

[0084] and Figure 9 Similarly, in Figure 10 The waveform depicts the magnitude of the change in voltage across the load of circuit 303 when power transmitting device 102 is coupled to power receiving device 108 to transmit power. Figure 10 Multiple modulation intervals, such as 1002, and multiple operation intervals, such as 1004, are described. Before time T1, the voltage across the load of the receiving circuit 303 is V. 01 With V lo The voltage varies between these values ​​to modulate the signal. Before time T1, the voltage remains at V during the operating interval. 01 Nearby. At time T1, the default states of the first switch 318 and any additional switches, such as the second switch 319, are converted to relative states. For example, if the default state before T1 is open, the default state after T1 is closed. If the default state before T1 is closed, the default state after T1 is open. Figure 10 As described in the text, after the default value is converted, the voltage will be at V during the modulation interval. 02 With V hi The values ​​change between and remain at V during the operation interval. 02 In or at V 02 The default state transition allows system 300 to reverse the modulation polarity from a decrease in voltage (before T1) to an increase in voltage (after T1). Therefore, if needed, undesirable low voltages across the load of circuit 303 can be avoided, and the voltage level can be maintained or potentially reduced during operating intervals. Furthermore, in various embodiments, the default state transition can occur without interrupting ongoing power transfer from power transmitting device 102 to power receiving device 108.

[0085] After the default state is switched at T1, when the power transmitting device 102 can receive the modulated signal and adjust the oscillating magnetic field adjustment according to the modulated signal, the voltage level increases during the operating interval until it reaches V. 02 There can be a transition period.

[0086] Figure 11 This is a flowchart illustrating a method for avoiding unwanted high or low voltages during wireless transmission.

[0087] At step 1101, the method begins. At step 1103, wireless power transfer can be initialized between the power transmitting device and the power receiving device, and the ASK polarity (positive (e.g., ...) for modulation) can be stored. Figure 5 And as described in 7a) or (negative (such as Figure 6 or Figure 7B(As depicted). At step 1105, it is checked whether SK modulation is in progress. At step 1110, the ADC senses the voltage after rectification. At step 1109, it can be determined whether the voltage after rectification is undesirable (too high or too low). At step 1111, the ASK polarity can be reversed at the end of the ongoing modulation interval. At step 1113, the method may include checking to see if wireless power transfer is complete.

[0088] Figure 12 A method 1200 for modulating signals is described.

[0089] Method 1200 may include: at step 1202, operating a circuit in a first arrangement during a first operating interval; at step 1204, switching the circuit between the first arrangement and a second arrangement during a first modulation interval to change the load on the circuit to generate a first amplitude shift keying (ASK) signal; at step 1206, detecting a voltage on the circuit that exceeds a threshold level; at step 1208, operating a circuit in a second arrangement during a second operating interval; and at step 1210, switching the circuit between the second arrangement and the first arrangement during a second modulation interval to change the load on the circuit to generate a second ASK signal.

[0090] Method 1200 may further include, wherein the first ASK signal and the second ASK signal are modulated according to a differential biphase coding scheme.

[0091] Method 1200 may further include establishing a wireless coupling between a power transmitter and a power receiver to transmit power for charging the battery of the power receiver, wherein the power receiver includes circuitry.

[0092] Method 1200 may further include maintaining wireless coupling during the first operating interval, the first modulation interval, the second operating interval, and the second modulation interval.

[0093] Method 1200 may further include: receiving a first ASK signal and a second ASK signal via a power transmitter; and adjusting the power level of the power transmitted from the power transmitter to the power receiver based on the first ASK signal, the second ASK signal, or both.

[0094] Method 1200 may further include switching the circuit from a first arrangement to a second arrangement by coupling one or more capacitors to the circuit.

[0095] Method 1200 may further include switching the circuit from a second arrangement to a first arrangement by decoupling one or more capacitors from the circuit.

[0096] Method 1200 may further include switching the circuit from a first arrangement to a second arrangement by decoupling one or more capacitors from the circuit.

[0097] Method 1200 may further include switching the circuit from a second arrangement to a first arrangement by coupling one or more capacitors from the circuit.

[0098] Figure 13 A method 1300 for modulating signals is described.

[0099] Method 1300 may include: at step 1302, operating a circuit in a first arrangement during a first operating interval; at step 1304, switching the circuit between a first arrangement and a second arrangement during a first modulation interval to change the load on the circuit to generate a first amplitude shift keying (ASK) signal, wherein switching the circuit from the first arrangement to the second arrangement increases the voltage across the circuit at the load; at step 1306, detecting a voltage on the circuit exceeding a threshold level; at step 1308, operating a circuit in a second arrangement during a second operating interval; and at step 1310, switching the circuit between a second arrangement and a first arrangement during a second modulation interval to change the load on the circuit to generate a second ASK signal, wherein switching the circuit from the second arrangement to the first arrangement decreases the voltage across the load on the circuit.

[0100] Method 1300 may further include modulating the first ASK signal and the second ASK signal according to a differential biphase coding scheme.

[0101] Method 1300 may further include: establishing a wireless coupling between a power transmitter and a power receiver to transmit power for charging a battery, wherein the power receiver includes circuitry; and maintaining the wireless coupling during a first operating interval, a first modulation interval, a second operating interval, and a second modulation interval.

[0102] Method 1300 may further include switching the circuit from a first arrangement to a second arrangement by coupling one or more capacitors to the circuit.

[0103] Method 1300 may further include switching the circuit from a second arrangement to a first arrangement by decoupling one or more capacitors from the circuit.

[0104] Method 1300 may further include switching the circuit from a first arrangement to a second arrangement by decoupling one or more capacitors from the circuit.

[0105] Method 1300 may further include switching the circuit from a second arrangement to a first arrangement by coupling one or more capacitors from the circuit.

[0106] Figure 14 A method 1400 for modulating signals is described.

[0107] Method 1400 may include: at step 1402, operating a circuit in a first arrangement during a first operating interval; at step 1404, switching the circuit between a first arrangement and a second arrangement during a first modulation interval to change the load on the circuit to generate a first amplitude shift keying (ASK) signal, wherein switching the circuit from the first arrangement to the second arrangement will decrease the voltage across the load on the circuit; at step 1406, detecting a voltage on the circuit that has dropped below a threshold level; at step 1408, operating a circuit in a second arrangement during a second operating interval; and at step 1410, switching the circuit between a second arrangement and a first arrangement during a second modulation interval to change the load on the circuit to generate a second ASK signal, wherein switching the circuit from the second arrangement to the first arrangement will increase the voltage across the load on the circuit.

[0108] Method 1400 may further include modulating the first ASK signal and the second ASK signal according to a differential biphase coding scheme.

[0109] Method 1400 may further include: establishing a wireless coupling between a power transmitter and a power receiver to transmit power for charging a battery, wherein the power receiver includes circuitry; and maintaining the wireless coupling during a first operating interval, a first modulation interval, a second operating interval, and a second modulation interval.

[0110] Method 1400 may further include switching the circuit from a first arrangement to a second arrangement by coupling one or more capacitors to the circuit.

[0111] Method 1400 may further include switching the circuit from a second arrangement to a first arrangement by decoupling one or more capacitors from the circuit.

[0112] Method 1400 may further include switching the circuit from a first arrangement to a second arrangement by decoupling one or more capacitors from the circuit.

[0113] Method 1400 may further include switching the circuit from a second arrangement to a first arrangement by coupling one or more capacitors from the circuit.

[0114] Example 1. A method for modulating a signal, comprising: operating a circuit in a first arrangement during a first operating interval; switching the circuit between the first arrangement and a second arrangement during the first modulation interval to change the load on the circuit to generate a first amplitude shift keying (ASK) signal; detecting a voltage on the circuit that exceeds a threshold level; operating a circuit in a second arrangement during a second operating interval; and switching the circuit between the second arrangement and the first arrangement during the second modulation interval to change the load on the circuit to generate a second ASK signal.

[0115] Example 2. According to the method described in Example 1, wherein the first ASK signal and the second ASK signal are modulated according to a differential biphase coding scheme.

[0116] Example 3. The method according to Example 1 or 2 further includes: establishing a wireless coupling between a power transmitter and a power receiver to transmit power to charge a battery of the power receiver, wherein the power receiver includes circuitry; maintaining the wireless coupling during a first operating interval, a first modulation interval, a second operating interval, and a second modulation interval; receiving a first ASK signal and a second ASK signal by the power transmitter; and adjusting the power level of the power transmitted from the power transmitter to the power receiver based on the first ASK signal, the second ASK signal, or both.

[0117] Example 4. The method according to Examples 1 to 3, wherein the circuit is switched from a first arrangement to a second arrangement by coupling one or more capacitors to the circuit.

[0118] Example 5. The method according to Examples 1 to 4, wherein the circuit is switched from a second arrangement to a first arrangement by decoupling one or more capacitors from the circuit.

[0119] Example 6. The method according to Examples 1 to 5, wherein the circuit is switched from a first arrangement to a second arrangement by decoupling one or more capacitors from the circuit.

[0120] Example 7. According to the method of Examples 1 to 6, the circuit is switched from the second arrangement to the first arrangement by coupling one or more capacitors from the circuit.

[0121] Example 8. A method for modulating a signal, comprising: operating a circuit in a first arrangement during a first operating interval; switching the circuit between the first arrangement and a second arrangement during the first modulation interval to change the load on the circuit to generate a first amplitude shift keying (ASK) signal, wherein switching the circuit from the first arrangement to the second arrangement increases the voltage across the load on the circuit; detecting a voltage on the circuit exceeding a threshold level; operating a circuit in a second arrangement during a second operating interval; and switching the circuit between the second arrangement and the first arrangement during the second modulation interval to change the load on the circuit to generate a second ASK signal, wherein switching the circuit from the second arrangement to the first arrangement decreases the voltage across the load on the circuit.

[0122] Example 9. The method according to Example 8, further comprising: establishing a wireless coupling between a power transmitter and a power receiver to transmit power for charging a battery, wherein the power receiver includes circuitry; maintaining the wireless coupling during a first operating interval, a first modulation interval, a second operating interval, and a second modulation interval; and wherein the first ASK signal and the second ASK signal are modulated according to a differential biphase coding scheme.

[0123] Example 10. The method according to Example 8 or 9, wherein the circuit is switched from a first arrangement to a second arrangement by coupling one or more capacitors to the circuit.

[0124] Example 11. According to the method of Examples 8 to 10, the circuit is switched from a second arrangement to a first arrangement by decoupling one or more capacitors from the circuit.

[0125] Example 12. The method according to Examples 8 to 11, wherein the circuit is switched from a first arrangement to a second arrangement by decoupling one or more capacitors from the circuit.

[0126] Example 13. The method according to Examples 8 to 12, wherein the circuit is switched from a second arrangement to a first arrangement by coupling one or more capacitors from the circuit.

[0127] Example 14. A method for modulating a signal, comprising: operating a circuit in a first arrangement during a first operating interval; switching the circuit between the first arrangement and a second arrangement during the first modulation interval to change the load on the circuit to generate a first amplitude shift keying (ASK) signal, wherein switching the circuit from the first arrangement to the second arrangement reduces the voltage across the load on the circuit; detecting a voltage on the circuit that has dropped below a threshold level; operating a circuit in a second arrangement during a second operating interval; and switching the circuit between the second arrangement and the first arrangement during the second modulation interval to change the load on the circuit to generate a second ASK signal, wherein switching the circuit from the second arrangement to the first arrangement increases the voltage across the load on the circuit.

[0128] Example 15. The method according to Example 14 further includes: establishing a wireless coupling between a power transmitter and a power receiver to transmit power for charging a battery, wherein the power receiver includes circuitry; maintaining the wireless coupling during a first operating interval, a first modulation interval, a second operating interval, and a second modulation interval; and wherein the first ASK signal and the second ASK signal are modulated according to a differential biphase coding scheme.

[0129] Example 16. The method according to Example 14 or 15, wherein the circuit is switched from a first arrangement to a second arrangement by coupling one or more capacitors to the circuit.

[0130] Example 17. The method according to Examples 14 to 16, wherein the circuit is switched from a second arrangement to a first arrangement by decoupling one or more capacitors from the circuit.

[0131] Example 18. The method according to Examples 14 to 17, wherein the circuit is switched from a first arrangement to a second arrangement by decoupling one or more capacitors from the circuit.

[0132] Example 19. According to the method of Examples 14 to 17, the circuit is switched from a second arrangement to a first arrangement by coupling one or more capacitors from the circuit.

[0133] Example 20. A system for wirelessly transmitting power from a power transmitting device to a power receiving device, comprising a power transmitting device including a transmitting circuit configured to be coupled to a power source; and a power receiving device including a receiving circuit configured to wirelessly receive power from the power transmitting device; a modulator including an output coupled to a control gate of a switch, wherein the modulator is configured to deliver a control signal to the control gate to switch the switch between an open state and a closed state to couple or decouple a capacitor from the receiving circuit; wherein the modulator is configured to: operate the switch during a modulation interval to change the load of the receiving circuit to generate an amplitude keying (ASK) signal; and maintain the switch in a default state during the operation interval, the default state including one of an open state or a closed state; and a processor communicating with the modulator and configured to execute a set of instructions stored in a non-transitory computer-readable medium to instruct the modulator to transition the default state to the other of the open or closed states while the receiving circuit is wirelessly receiving power.

[0134] Example 21. The system according to Example 20, wherein the ASK signal is modulated according to a differential biphase coding scheme.

[0135] Example 22. The system according to Example 20 or 21, wherein the transmitting circuit includes a first inductor coil configured to generate an oscillating magnetic field to induce a current in the receiving circuit.

[0136] Example 23. The system according to Examples 20 to 23, wherein the power transmitting device is configured to receive an ASK signal and adjust the oscillating magnetic field according to the ASK signal.

[0137] Example 24. The system according to Examples 20 to 24, wherein the power receiving device further includes an analog-to-digital converter configured to convert voltage levels across a load of the receiving circuit into digital signals, wherein a processor is configured to receive the digital signals and, when the voltage level at the load exceeds a threshold level, the processor is triggered to instruct the modulator to switch to a default state.

[0138] The reference numerals used herein are provided for convenience only and therefore do not define the extent of protection or the scope of embodiments.

[0139] References to illustrative embodiments in this specification are not intended to be construed in a limiting sense. Various modifications and combinations thereof will be apparent to those skilled in the art from the specification, exemplary embodiments, and other embodiments. Therefore, it is intended that the appended claims cover any such modifications or embodiments.

Claims

1. A method for modulating a signal, comprising: in a first time period, operating a power receiver circuit in a first arrangement during a first operating interval of the first time period, wherein the first time period includes the first operating interval and a first modulation interval; in the first time period, switching the power receiver circuit between the first arrangement and a second arrangement during the first modulation interval of the first time period to cause a change in a load on the power receiver circuit to produce a first amplitude shift keying (ASK) signal, wherein the first ASK signal is configured to carry a first digital value for reception by a power transmitter circuit; in response to detecting that a voltage on the power receiver circuit crosses a threshold level, in a second time period, operating the power receiver circuit in the second arrangement during a second operating interval of the second time period, wherein the second time period includes the second operating interval and a second modulation interval; and in the second time period, switching the power receiver circuit between the second arrangement and the first arrangement during the second modulation interval of the second time period to cause the change in the load on the power receiver circuit to produce a second ASK signal, wherein the second ASK signal is configured to carry a second digital value for reception by the power transmitter circuit, wherein the first time period and the second time period are two adjacent time periods of a plurality of consecutive time periods, wherein a data transmission between the power receiver circuit and the power transmitter circuit occurs during each time period of the plurality of consecutive time periods.

2. The method of claim 1, wherein the first ASK signal and the second ASK signal are modulated according to a differential bi-phase encoding scheme.

3. The method of claim 1, further comprising: establishing a wireless coupling between a power transmitter and a power receiver to transfer power to charge a battery of the power receiver, wherein the power receiver includes the power receiver circuit; maintaining the wireless coupling during the first operating interval, the first modulation interval, the second operating interval, and the second modulation interval; receiving, by the power transmitter, the first ASK signal and the second ASK signal; and adjusting a power level of the power transferred from the power transmitter to the power receiver based on the first ASK signal, the second ASK signal, or both.

4. The method of claim 1, wherein the power receiver circuit is switched from the first arrangement to the second arrangement by coupling one or more capacitors to the power receiver circuit.

5. The method of claim 1, wherein the power receiver circuit is switched from the second arrangement to the first arrangement by decoupling one or more capacitors from the power receiver circuit. ​ 6. The method of claim 1, wherein the power receiver circuit is switched from the first arrangement to the second arrangement by decoupling one or more capacitors from the power receiver circuit.

7. The method of claim 1, wherein the power receiver circuit is switched from the second arrangement to the first arrangement by coupling one or more capacitors from the power receiver circuit.

8. The method of claim 1, wherein detecting the voltage comprises: detecting the voltage on the circuit crossing the threshold level when data transmission occurs between the power receiver circuit and the power transmitter circuit.

9. The method of claim 1, wherein the first time period and the second time period have durations equal to bit periods of the first ASK signal and the second ASK signal, respectively.

10. The method of claim 1, wherein the first time period has a duration equal to a sum of a first duration of a first operating period and a second duration of a first modulation period.

11. A method for modulating a signal, comprising: operating a power receiver circuit in a first arrangement during a first operating interval of a first time period, wherein the first time period includes the first operating interval and a first modulation interval; switching the power receiver circuit between the first arrangement and a second arrangement during the first modulation interval of the first time period to vary a load on the power receiver circuit to produce a first amplitude shift keying (ASK) signal, wherein switching the power receiver circuit from the first arrangement to the second arrangement increases a voltage across the load on the power receiver circuit, wherein the first ASK signal is configured to carry a first digital value for reception by a power transmitter circuit; in response to detecting the voltage on the power receiver circuit exceeding a threshold level, operating the power receiver circuit in the second arrangement during a second operating interval of a second time period, wherein the second time period includes the second operating interval and a second modulation interval; and switching the power receiver circuit between the second arrangement and the first arrangement during the second modulation interval of the second time period to vary the load on the power receiver circuit to produce a second ASK signal, wherein switching the power receiver circuit from the second arrangement to the first arrangement decreases the voltage across the load on the power receiver circuit, wherein the second ASK signal is configured to carry a second digital value for reception by the power transmitter circuit, wherein the first time period and the second time period are two adjacent time periods of a plurality of consecutive time periods, wherein data transmission between the power receiver circuit and the power transmitter circuit occurs during each time period of the plurality of consecutive time periods.

12. The method of claim 11, further comprising: establishing a wireless coupling between a power transmitter and a power receiver to transfer power to charge a battery of the power receiver, wherein the power receiver includes the power receiver circuit; maintaining the wireless coupling during the first operating interval, the first modulation interval, the second operating interval, and the second modulation interval; and wherein the first ASK signal and the second ASK signal are modulated according to a differential bi-phase encoding scheme.

13. The method of claim 11, wherein the power receiver circuit is switched from the first arrangement to the second arrangement by coupling one or more capacitors to the power receiver circuit.

14. The method of claim 11, wherein the power receiver circuit is switched from the second arrangement to the first arrangement by decoupling one or more capacitors from the power receiver circuit.

15. The method of claim 11, wherein the power receiver circuit is switched from the first arrangement to the second arrangement by decoupling one or more capacitors from the power receiver circuit.

16. The method of claim 11, wherein the power receiver circuit is switched from the second arrangement to the first arrangement by coupling one or more capacitors from the power receiver circuit.

17. The method of claim 11, wherein detecting the voltage comprises: detecting the voltage on the circuit exceeding the threshold level when data transmission occurs between the power receiver circuit and the power transmitter circuit.

18. A method for modulating a signal, comprising: operating a power receiver circuit in a first arrangement during a first operating interval of a first time period, wherein the first time period comprises the first operating interval and a first modulation interval; switching the power receiver circuit between the first arrangement and a second arrangement during the first modulation interval of the first time period to cause a change in a load on the power receiver circuit to produce a first amplitude shift keying (ASK) signal, wherein switching the power receiver circuit from the first arrangement to the second arrangement decreases a voltage across the load on the power receiver circuit, wherein the first ASK signal is configured to carry a first digital value for reception by a power transmitter circuit; in response to detecting the voltage on the power receiver circuit falling below a threshold level, operating the power receiver circuit in the second arrangement during a second operating interval of a second time period, wherein the second time period comprises the second operating interval and a second modulation interval; and during the second modulation interval of the second time period, switching the power receiver circuit between the second arrangement and the first arrangement to cause a change in the load on the power receiver circuit to produce a second ASK signal, wherein switching the power receiver circuit from the second arrangement to the first arrangement increases the voltage across the load on the power receiver circuit, wherein the second ASK signal is configured to carry a second digital value for reception by the power transmitter circuit, wherein the first time period and the second time period are two adjacent time periods in a plurality of consecutive time periods, wherein data transmission between the power receiver circuit and the power transmitter circuit occurs during each time period in the plurality of consecutive time periods.

19. The method of claim 18, further comprising: establishing a wireless coupling between a power transmitter and a power receiver to transfer power to charge a battery of the power receiver, wherein the power receiver comprises the power receiver circuit; maintaining the wireless coupling during the first operation interval, the first modulation interval, the second operation interval, and the second modulation interval; and wherein the first ASK signal and the second ASK signal are modulated according to a differential bi-phase encoding scheme.

20. The method of claim 18, wherein the power receiver circuit is switched from the first arrangement to the second arrangement by coupling one or more capacitors to the power receiver circuit.

21. The method of claim 18, wherein the power receiver circuit is switched from the second arrangement to the first arrangement by decoupling one or more capacitors from the power receiver circuit.

22. The method of claim 18, wherein the power receiver circuit is switched from the first arrangement to the second arrangement by decoupling one or more capacitors from the power receiver circuit.

23. The method of claim 18, wherein the power receiver circuit is switched from the second arrangement to the first arrangement by coupling one or more capacitors from the power receiver circuit.

24. The method of claim 18, wherein detecting the voltage comprises: detecting the voltage on the circuit falling below the threshold level when data transmission occurs between the power receiver circuit and the power transmitter circuit.

25. The method of claim 18, wherein a duration of the first time period is equal to a sum of a first duration of the first operation period and a second duration of the first modulation period.

26. A system for wirelessly transferring power from a power transmitting device to a power receiving device, comprising: a power transmitting device comprising a transmitting circuit, the power transmitting device configured to be coupled to a power source; and a power receiving device comprising: a receiving circuit configured to wirelessly receive power from the power transmitting device; a modulator including an output coupled to a control gate of a switch, wherein the modulator is configured to deliver a control signal to the control gate to switch the switch between an open state and a closed state to couple or decouple a capacitor from the receive circuit; wherein the modulator is configured to: operate the switch during a modulation interval to cause a change in a load of the receive circuit to produce an amplitude shift keying (ASK) signal; and maintain the switch in a default state during an operation interval, the default state comprising one of the open state or the closed state; and a processor in communication with the modulator and configured to execute a set of instructions stored in a non-transitory computer readable medium to instruct the modulator to convert the default state to the other of the open state or the closed state while the receive circuit wirelessly receives power, and the processor is configured to be triggered to instruct the modulator to convert the default state when the voltage level at the load crosses a threshold level.

27. The system of claim 26, wherein the ASK signal is modulated according to a differential bi-phase encoding scheme.

28. The system of claim 26, wherein the transmit circuit comprises a first inductive coil configured to generate an oscillating magnetic field to induct a current in the receive circuit.

29. The system of claim 28, wherein the power transmitting device is configured to receive the ASK signal and adjust the oscillating magnetic field according to the ASK signal.

30. The system of claim 26, wherein the power receiving device further comprises an analog-to-digital converter configured to convert a voltage level across the load of the receive circuit to a digital signal, wherein the processor is configured to receive the digital signal and is triggered to instruct the modulator to convert the default state when the voltage level at the load exceeds a threshold level.

31. The system of claim 26, wherein the power receiving device further comprises an analog-to-digital converter configured to convert a voltage level at the load of the receive circuit to a digital signal, wherein the processor is configured to receive the digital signal and is triggered to instruct the modulator to convert the default state when the voltage level at the load falls below a threshold level.

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