Wireless power transfer

Abstract

A power receiver (105) wirelessly receives power from a power transmitter (101) through an electromagnetic power transfer signal. The power transmitter (101) can frequency or phase modulate the power transfer signal using a data value pattern per data symbol, where each data value is represented by a constant modulation level in a modulation time interval. The data values can be detected by a power receiver communicator (509) of the power receiver (105) from a frequency and / or phase difference of consecutive modulation time intervals. Data transmission can use frequency shift keying or phase shift keying, while demodulation / detection is based on differential frequency / phase detection. This can improve and simplify data transmission from the power transmitter to the power receiver.

Description

Technical Field

[0001] This invention relates to wireless power transmission, and more particularly, but not exclusively, to communication in power transmission systems (e.g., wireless power transmission systems operating according to elements of the Qi wireless power transmission specification). Background Technology

[0002] Most electrical products today require dedicated electrical contacts to be powered from an external power source. However, this is often impractical and requires users to physically insert connectors or otherwise establish physical electrical contact. To provide a significantly improved user experience, the use of wireless power has been proposed, where power is inductively transferred from a transmitter coil in a power transmitter device to a receiver coil in each device.

[0003] Power transfer via magnetic induction is a well-known concept, primarily used in transformers where the primary transmitter inductor / coil and the secondary receiver coil are tightly coupled. Wireless power transfer between these two devices can be achieved by placing the primary transmitter coil and the secondary receiver coil separately in the two devices, based on the principle of loosely coupled transformers.

[0004] This arrangement enables wireless power transfer to devices without any wires or physical electrical connections. In fact, it simply requires placing the device near or on top of the transmitter coil to charge or power it externally. For example, the power transmitter device can be positioned on a horizontal surface, and the device can be powered simply by placing it on that surface.

[0005] Furthermore, such wireless power transmission devices can be advantageously designed to enable power transmitter devices to work with a variety of power receiver devices. Specifically, a wireless power transmission method known as the "Qi specification" has been defined and is currently under further development. This method allows Qi-compliant power transmitter devices to work with equally Qi-compliant power receiver devices, without them needing to be from the same manufacturer or be proprietary to each other. The Qi standard also includes features to allow operation to be adjusted based on the specific power receiver device (e.g., depending on specific power consumption). Based on the Qi specification, a method known as the "Ki specification" is being developed for high-power applications (e.g., specifically for kitchen appliances).

[0006] To support efficient wireless power transmission, wireless power transmission systems employ extensive communication between the power transmitter and the power receiver.

[0007] In some wireless power transmission systems (such as the Qi system), communication employs frequency modulation of the power transmission signal to transmit data from the power transmitter to the power receiver. However, while this traditional method can provide effective communication in many scenarios, it is often not optimal or ideal in all practical implementations and situations. For example, in many cases, its communication performance may be less than ideal in terms of communication capacity and / or reliability. It often requires higher complexity and functional support, which can increase costs. Traditional communication methods may lead to poor user experience and / or power transmission performance in many practical scenarios. Examples of communication methods for wireless power transmission systems are disclosed in EP 4 084 282 A1 and EP 4 270 731 A1.

[0008] Therefore, improved methods will be advantageous, especially those that can achieve one or more of the following advantages: greater flexibility, lower cost, lower complexity, improved power transmission operation, higher reliability, fewer communication errors, better backward compatibility, improved communication from power transmitter to power receiver, improved and / or simplified demodulation of modulated power transmission signals, higher efficiency, and / or better performance. Summary of the Invention

[0009] Therefore, the present invention aims to mitigate, alleviate or eliminate one or more of the above-mentioned disadvantages, preferably alone or in any combination.

[0010] According to one aspect of the invention, a power receiver is provided for wirelessly receiving power from a power transmitter via an electromagnetic power transmission signal, the power receiver comprising: an input circuit including a receiver coil arranged to extract power from the power transmission signal to generate an induced power signal; a power receiver controller arranged to control the operation of the power receiver based on data received from the power transmitter; and a communicator arranged to receive data symbols transmitted from the power transmitter, each data symbol having a data symbol value and modulated onto the power transmission signal using a modulation scheme in which each (possible) data symbol value is associated with a different predetermined chip sequence of one or more binary chip values. In this communication, each binary chip value is represented by a constant modulation level within a chip time interval, each constant modulation level being at least one of a constant frequency of the power transmission signal and a constant phase of the power transmission signal, the constant modulation level remaining constant between a number of consecutive chip time intervals; wherein the communicator is arranged to: for each of at least a number of chip time intervals, determine the difference between a measured modulation level within the chip time interval and a measured modulation level within the immediately preceding chip time interval, and determine a received binary chip value within the chip time interval based on the difference; and determine a data symbol value by comparing a received chip sequence formed from the received binary chip values ​​with the different predetermined chip sequences.

[0011] This invention can achieve improved performance in many embodiments, and in particular, improved communication between a power transmitter and a power receiver in many embodiments. It can achieve improved power transfer in many embodiments. The method can allow the use of differential methods to demodulate frequency shift keying and / or phase shift keying. This can provide improved demodulation results and / or reduced complexity in many scenarios. For example, it can eliminate or avoid the requirement for the power receiver to determine an accurate frequency / phase reference.

[0012] Each data value in a set of data values ​​can be associated with a different predetermined chip sequence / pattern in a set of predetermined chip sequences / patterns with constant modulation levels. Each constant modulation level can remain constant within a modulation time interval. Each pattern / predetermined chip sequence in the set of patterns / predetermined chip sequences can include one or more modulation / chip time intervals, and therefore can include one or more constant modulation level time intervals.

[0013] The communicator is configured to determine the data symbol value of a given data symbol as the data symbol value associated with the predetermined chip sequence / pattern that most closely matches the received chip sequence / pattern of the given data symbol among the different predetermined chip sequences / patterns.

[0014] The constant modulation level can remain unchanged between some consecutive modulation / chip time intervals of at least some of the different predetermined chip sequences / modes (when the different predetermined chip sequences / modes include multiple modulation / chip time intervals), or between some consecutive modulation / chip time intervals of the different predetermined chip sequences / modes / data symbols (e.g., when each predetermined chip sequence / mode includes only a single modulation / chip time interval).

[0015] The operation of the power receiver can be a power transfer operation. The power receiver controller can be configured to extract power from the power transfer signal based on the data symbol value.

[0016] Each constant modulation level can be one of a set of several constant modulation levels. In some embodiments, the number of constant modulation levels can be 2, 3, or 4. In many embodiments, the number of constant modulation levels can not exceed 4, 8, or 16.

[0017] According to an optional feature of the invention, the different predetermined chip sequences include only one binary chip value.

[0018] This can provide improved performance and / or operation for power transmission systems. In many scenarios, this can achieve higher data rates while still maintaining efficient, low-complexity, and / or reliable communication.

[0019] According to an optional feature of the invention, the different predetermined chip sequences include not less than four binary chip values.

[0020] This can provide improved performance and / or operation of power transmission systems. In particular, in many embodiments, this can provide reliable communication and lower data rates while achieving lower modulation depth (e.g., smaller frequency variations). Lower modulation depth, especially smaller frequency variations, can reduce fluctuations / noise, thereby improving power transmission.

[0021] Each modulation time interval can correspond to one chip in the spreading chip sequence. Communication can use the direct sequence spreading method, employing a chip sequence of no fewer than four chips. Each modulation time interval can be one chip time interval in the chip sequence. Each data symbol can be represented by a different chip sequence.

[0022] According to an optional feature of the invention, the modulation scheme includes a start time interval preceding a chip time interval of a predetermined chip sequence (in the different predetermined chip sequences) for a data symbol; and wherein the communicator is arranged to determine a previously measured modulation level within an initial chip time interval of the predetermined chip sequence for the data symbol as a modulation level measured within the start time interval.

[0023] This can provide improved performance and / or operation of power transmission systems. In particular, it can improve the communication and reception of initial data values, thereby providing improved overall communication, typically including a reduced data rate.

[0024] According to an optional feature of the invention, the constant modulation level during the start time interval is constrained to be different from the constant modulation level during the initial chip time interval.

[0025] This can provide improved performance and / or operation of power transmission systems. In particular, it can improve and / or simplify data communication from the power transmitter to the power receiver.

[0026] According to an optional feature of the invention, the different predetermined chip sequences are arranged such that the longest consecutive chip time interval sequence having the same binary chip value immediately follows the start time interval.

[0027] This can provide improved performance and / or operation of power transmission systems. In particular, it can improve and / or simplify data communication from the power transmitter to the power receiver.

[0028] According to an optional feature of the invention, the modulation scheme includes a plurality of constant modulation levels associated with at least a first binary chip value, and wherein, in response to the number of consecutive chip time intervals having the first constant modulation level among the plurality of constant modulation levels exceeding a threshold, the first binary chip value is changed from being represented by the first constant modulation level to being represented by a second constant modulation level among the plurality of constant modulation levels.

[0029] This can provide improved performance and / or operation of power transmission systems. In particular, it can improve differential detection. In many embodiments, the threshold can be an integer in the range of 2 to 15, typically 2, 3, or 4.

[0030] According to an optional feature of the invention, the difference between the first constant modulation level and the constant modulation level associated with a binary chip value different from the first binary chip value is less than the difference between the second constant modulation level and the constant modulation level associated with the different binary chip value.

[0031] This can improve and / or simplify data communication from the power transmitter to the power receiver.

[0032] According to one aspect of the present invention, a power transmission system is provided, comprising a power receiver as described above and a power transmitter for providing power to the power receiver, the power transmitter comprising: an output circuit including a transmitter coil arranged to generate a power transmission signal in response to a drive signal applied to the output circuit; a driver arranged to generate the drive signal; and a first communicator arranged to transmit data to the power receiver by modulating the power transmission signal using the modulation scheme in which each data symbol value is represented by a different predetermined sequence of at least one binary chip value, each binary chip value is represented by a constant modulation level in a chip time interval, each constant modulation level being at least one of a constant frequency and a constant phase of the power transmission signal during the chip time interval, the constant modulation level remaining constant between a number of consecutive chip time intervals.

[0033] This can provide improved performance and / or operation of power transmission systems. In particular, it can improve and / or simplify data communication from the power transmitter to the power receiver.

[0034] According to an optional feature of the invention, each constant modulation level is a constant frequency, and the first communicator is arranged to transmit data to the power receiver during communication time intervals and to apply frequency variations to the power transmission signal during time intervals between the communication time intervals.

[0035] This can provide improved performance and / or operation of power transmission systems. In particular, it can improve and / or simplify data communication from the power transmitter to the power receiver.

[0036] According to an optional feature of the invention, the first communicator is arranged to apply a frequency variation, the correlation of which with each frequency mode of the different predetermined chip sequences is less than the correlation between any constant frequency and each frequency mode of the different predetermined chip sequences.

[0037] This can provide improved performance and / or operation of power transmission systems. In particular, it can improve and / or simplify data communication from the power transmitter to the power receiver.

[0038] According to another aspect of the present invention, an operating method is provided for a power receiver to wirelessly receive power from a power transmitter via an electromagnetic power transmission signal, the power receiver comprising: an input circuit including a receiver coil that extracts power from the power transmission signal to generate an induced power signal; a power receiver controller arranged to control the operation of the power receiver based on data received from the power transmitter; and a communicator arranged to receive data symbols transmitted from the power transmitter, each data symbol having a data symbol value and modulated onto the power transmission signal using a modulation scheme in which each (possible) data symbol value is associated with a different predetermined chip sequence of one or more binary chip values. The binary chip value is represented by a constant modulation level in a chip time interval, each constant modulation level being at least one of a constant frequency of the power transmission signal and a constant phase of the power transmission signal, the constant modulation level remaining constant between a number of consecutive chip time intervals; wherein the method includes the communicator performing the following steps: for each chip time interval in at least a number of chip time intervals, determining the difference between a measured modulation level in the chip time interval and a measured modulation level in the immediately preceding chip time interval, and determining a received binary chip value in the chip time interval based on the difference; and determining a data symbol value by comparing a received chip sequence formed from the received binary chip values ​​with the different predetermined chip sequences.

[0039] These and other aspects, features, and advantages of the invention will become apparent and will be explained from the embodiments described below. Attached Figure Description

[0040] Embodiments of the invention will be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 Examples of elements of a power transmission system according to some embodiments of the present invention are shown; Figure 2 Examples of elements of a power transmitter according to some embodiments of the present invention are shown; Figure 3 An example of a half-bridge inverter for a power transmitter is shown; Figure 4 An example of a full-bridge inverter for a power transmitter is shown; Figure 5 Examples of elements of a power receiver according to some embodiments of the present invention are shown; Figure 6 An example of a chip sequence is shown; Figure 7 An example of frequency variation in a wireless power transmission system is shown; Figure 8 Examples of signals in a wireless power transmission system including a power receiver and a power transmitter, according to some embodiments of the present invention, are shown; and Figure 9 An example of detection correlation for communication is shown in a wireless power transmission system including a power receiver and a power transmitter, according to some embodiments of the present invention. Detailed Implementation

[0041] The following description focuses on embodiments of the invention applicable to high-power wireless power delivery systems utilizing power delivery methods known from the Qi specification. However, it should be understood that the invention is not limited to this application, but can be applied to many other wireless power delivery systems.

[0042] Figure 1 An example of a power transmission system according to some embodiments of the present invention is shown. The power transmission system includes a power transmitter 101, which includes (or is coupled to) a transmitter coil / inductor 103. The system also includes a power receiver 105, which includes (or is coupled to) a receiver coil / inductor 107.

[0043] This system provides an inductive electromagnetic power transfer signal that can inductively transfer power from a power transmitter 101 to a power receiver 105. Specifically, the power transmitter 101 generates an electromagnetic signal that propagates as magnetic flux through a transmitter coil or inductor 103. The frequency of the power transfer signal is typically between about 20 kHz and about 500 kHz, and in many practical systems it can be about 120-150 kHz. The transmitter coil 103 is loosely coupled to the power receiving coil 107, so the power receiving coil 107 picks up (at least a portion) of the power transfer signal from the power transmitter 101. Therefore, power is transferred from the power transmitter 101 to the power receiver 105 via wireless inductive coupling from the transmitter coil 103 to the power receiving coil 107. The term "power transmission signal" is primarily used to refer to the induced signal / magnetic field (magnetic flux signal) between the transmitter coil 103 and the power receiving coil 107, but it should be understood that, equivalently, it can also be regarded as and used to refer to the electrical signal provided to the transmitter coil 103 or picked up by the power receiving coil 107.

[0044] In this example, power receiver 105 specifically receives power through receiver coil 107. However, in other embodiments, power receiver 105 may include a metallic element, such as a metal heating element, in which case the power transmission signal directly induces eddy currents, thereby directly heating the element.

[0045] In the following description, the operation of the power transmitter 101 and the power receiver 105 will be described with specific reference to embodiments generally based on the Qi or Ki specifications (except for the modifications and enhancements described herein (or derived therefrom)).

[0046] Many wireless power transfer systems utilize resonant power transfer, where the transmitter coil 103 is part of a resonant circuit, and typically the receiver coil 107 is also part of a resonant circuit. In many embodiments, the resonant circuit can be a series resonant circuit, so the transmitter coil 103 and receiver coil 107 can be coupled in series with corresponding resonant capacitors. Using a resonant circuit often provides more efficient power transfer.

[0047] Typically, wireless power transmission systems employ a power control loop to guide the system to the appropriate operating point. This power control loop alters the amount of power transmitted from the power transmitter to the power receiver. The received power (or voltage or current) can be measured and combined with the setpoint power value to generate an error signal. The power receiver transmits this error signal to the power control function in the power transmitter to reduce static error, ideally reducing it to zero.

[0048] Figure 2 Showing more details Figure 1 Components of the medium-power transmitter 101.

[0049] The power transmitter 101 includes a driver 201 that generates a drive signal fed to a transmitter coil 103, which in turn generates an electromagnetic power transfer signal to provide power transfer to a power receiver 105. The transmitter coil 103 is part of an output resonant circuit that includes the transmitter coil 103 and a capacitor 203. In this example, the output resonant circuit is a series resonant circuit; however, it should be understood that in other embodiments, the output resonant circuit may be a parallel resonant circuit. It should be understood that any suitable resonant circuit can be used, including resonant circuits using multiple inductors and / or capacitors.

[0050] Driver 201 generates current and voltage that are fed to the output resonant circuit and subsequently to the transmitter coil 103. Driver 201 is typically a drive circuit in the form of an inverter, which generates an AC signal from a DC voltage. The output of driver 201 is typically a switching bridge, through which a drive signal is generated by the appropriate switching of switches. Figure 3 A half-bridge switching inverter is shown. Switches S1 and S2 are controlled so that they never close simultaneously. Alternatingly, S1 closes while S2 is open, and vice versa. The switches open and close at a desired frequency, thereby generating an AC signal at the output. Typically, the inverter output is connected to a transmitter inductor via a resonant capacitor. Figure 4A full-bridge switched bridge / inverter is shown. Switches S1 and S2 are controlled to never be closed simultaneously. Switches S3 and S4 are also controlled to never be closed simultaneously. Alternatingly, switches S1 and S4 are closed while S2 and S3 are open, and then S2 and S3 are closed while S1 and S4 are open, thus generating a square wave signal at the output. The switches open and close at a desired frequency.

[0051] The power transmitter 101 also includes a power transmitter controller 205, which is arranged to control the operation of the power transmitter 101 according to a desired operating principle. Specifically, the power transmitter 101 may include many functions required to perform power control according to Qi or Ki specifications.

[0052] The power transmitter controller 205 is specifically arranged to control the driver 201 to generate a drive signal, and can specifically control the power level of the drive signal, thereby controlling the level of the generated power transmission signal. The power transmitter controller 205 includes a power loop controller that controls the power level of the power transmission signal in response to a power control message received from the power receiver 105 during the power transmission phase.

[0053] To communicate with the power receiver, the power transmitter 101 also includes a power transmitter communicator 207, which is arranged to communicate with the complementary communicator of the power receiver. Specifically, the power transmitter communicator 207 is arranged to communicate with the power receiver (its complementary communicator) using a power transmission signal as a communication carrier. For example, a range of different messages can be exchanged, such as those specified in the Qi specification. A message may include one or more data bits / symbols.

[0054] In the direction from the power receiver to the power transmitter, the power receiver can load modulate the power transmission signal to transmit data to the power transmitter. As is well known to those skilled in the art, with load modulation, the power transmitter communicator 207 can detect changes in the load of the power receiver on the power transmission signal, and the power receiver can change the load according to the data value to be transmitted.

[0055] In the direction from the power transmitter to the power receiver, communication is achieved in the described method by frequency and / or phase modulation of the power transmission signal. The power transmitter communicator 207 may specifically apply frequency-shift keying and / or phase-shift keying, wherein the power transmitter communicator 207 controls the power transmitter controller 205 and driver 201 to apply a specific frequency and / or phase pattern according to the data symbols to be transmitted. Such a pattern can therefore correspond to a predetermined chip sequence. The power receiver can evaluate the signal induced in the receiver coil 107 (from the power transmission signal) and demodulate the signal according to the modulation used, thereby extracting the data transmitted in the forward direction (from the power transmitter to the power receiver). Specifically, the power receiver communicator can measure the frequency / phase and detect the transmitted data symbols by comparing the received frequency / phase pattern / chip sequence with a predetermined pattern / chip sequence of different data symbol values.

[0056] Figure 5 Some exemplary components of the power receiver 105 are shown.

[0057] In this example, receiver coil 107 is coupled to power receiver controller 501 via capacitor 503, which, together with receiver coil 107, forms an input resonant circuit. Therefore, power transfer can be resonant power transfer between resonant circuits. In other embodiments, only one or both of the power receiver and power transmitter may not use resonant circuits for power transfer.

[0058] Power receiver controller 501 couples receiver coil 107 to load 505 via switch 507. Power receiver controller 501 includes a power control path that converts the power extracted by receiver coil 107 into a power supply suitable for load 505. In some embodiments, power receiver controller 501 may provide a direct power path, simply connecting the input resonant circuit to switch 507 or load 505; that is, the power path of power receiver controller 501 may be implemented using only two wires. In other embodiments, the power path may include, for example, a rectifier and possibly a smoothing capacitor to provide a DC voltage. In still other embodiments, the power path may include more complex functions such as voltage control circuitry, impedance matching circuitry, current control circuitry, etc. Similarly, it should be understood that switch 507 may only exist in some embodiments, and in some embodiments, load 505 may be permanently coupled to the input resonant circuit.

[0059] Load 505 represents the target load used for power transfer. Load 505 can be, for example, an external device, a battery, or a charging function. Load 505 can also represent a load of internal circuitry, such as control circuitry, support circuitry, and auxiliary circuitry that support power transfer.

[0060] In addition, the power receiver controller 501 may include various power receiver controller functions required to perform power transfer, particularly those required to perform power transfer in accordance with the Qi specification.

[0061] The power transmitter also includes a power receiver communicator 509, which is arranged to communicate with the power transmitter to exchange data messages. The power receiver communicator 509 is a complementary communicator to the power transmitter communicator 207, specifically arranged to transmit data to the power transmitter by load modulating the power transmission signal. For example, the power receiver communicator 509 can be arranged to switch a communication capacitor on / off, for example, in parallel with the power receiver controller 501 or with the resonant capacitor 503, thereby enabling changes to the load and resonant frequency of the power transmission signal.

[0062] Furthermore, the power receiver communicator 509 is arranged to receive data from the power transmitter that has been modulated onto the power transmission signal by phase and / or frequency. As previously described, the power receiver communicator 509 can specifically measure / determine the phase and / or frequency of the power transmission signal during a given time interval and continue to determine the received data based on these measurements. The power receiver communicator 509 can further employ novel differential methods, which will be described in more detail later.

[0063] Power receiver communicator 509 may be coupled to power receiver controller 501 and is arranged to provide received data to power receiver controller 501 for processing, and to receive data from power receiver controller 501 for transmission to power transmitter. For example, power receiver communicator 509 may receive power error control data from power receiver controller 501 and may use load modulation to transmit the corresponding power error control message to power transmitter. It should be understood that many different functions and operations of the power receiver (and power transmitter) generally depend on data received from complementary entities. In particular, power transmission operations generally depend on data received from complementary devices.

[0064] For example, during power transmission, the system is configured to control the drive signal such that the power transmission signal reaches suitable operating parameters / attributes and that power transmission operates at a suitable operating point. To this end, the power transmitter is configured to use a power control loop to control the parameters of the drive signal, wherein the power attributes of the power transmission signal / drive signal are controlled in response to a power control error message received from the power receiver.

[0065] At regular, typically frequent intervals, the power receiver transmits power control error messages to the power transmitter. In some embodiments, a direct power setpoint change message indicating the desired absolute power level (rather than a relative error message) may be transmitted. The power receiver 105 includes functions to support this power control loop; for example, the power receiver controller 501 may continuously monitor the power or voltage of the load signal supplied to the load and detect whether it is higher or lower than a desired value. It may generate power control error messages at regular intervals, requesting an increase or decrease in the power level of the power transmission signal, and transmit these power control error messages to the power transmitter. Such error control messages, as well as other messages, may be transmitted via load modulation.

[0066] As another example, a power transmitter can transmit various commands and configuration data to a power receiver. For instance, parameters for power transmission can be established or negotiated during the power transmission initialization phase. Such operations typically involve bidirectional data transmission.

[0067] The power transmitter communicator 207 and the power receiver communicator 509 are arranged to communicate in the direction from the power transmitter to the power receiver by modulating the phase and / or frequency of the power transmission signal. Specifically, the system may use specific modulation and demodulation methods, which will be described below.

[0068] The communication method can specifically be Frequency Shift Keying (FSK) or Phase Shift Keying (PSK). Simultaneously, the power receiver communicator 509 can use a differential demodulation method to demodulate the signal, which can provide improved performance in many scenarios. The following description will focus on frequency modulation, particularly the case where the power transmitter uses FSK; however, it should be understood that the described methods and principles are equally (with necessary modifications) applicable to phase modulation, especially PSK.

[0069] In the modulation scheme used, each data symbol is represented by modulation in one or more modulation / chip time intervals, where the modulation level is constant within each modulation / chip time interval; that is, each data symbol is represented by multiple modulation / chip time intervals in which the frequency and / or phase of the power transmission signal is constant. The modulation level is constant within each modulation / chip time interval, but can vary between modulation / chip time intervals. Each constant modulation level can take one of a set of predetermined levels, such as one of a set of predetermined frequencies and / or phases. Each modulation / chip time interval corresponds to / provides a given constant modulation level. Furthermore, each constant modulation level is associated with a modulation / chip time interval data value, specifically referred to as a binary chip value. Each modulation / chip time interval can represent a binary chip value, where the data value is represented by different modulation levels (specifically, frequencies). For example, binary communication can be implemented in such a way that the binary chip value "0" is represented by a first frequency (e.g., 100 kHz) and the binary chip value "1" is represented by a second frequency (e.g., 99 kHz) (or, for example, a phase value of +90° for "1" and a phase value of -90° for "0").

[0070] Therefore, each data symbol is modulated onto the power transmission signal by a pattern / predetermined chip sequence of one or more modulation / chip time intervals, wherein each chip time interval has a constant modulation level corresponding to a constant frequency and / or phase of the power transmission signal. Each possible data symbol value is associated with / represented as one or more different pattern / predetermined chip sequences of constant modulation levels (each constant modulation level is constant over the duration of one modulation / chip time interval). Thus, each data symbol can be represented by a sequence / pattern of one or more chip time intervals, each with a constant modulation level. In the following text, the modulation / chip time interval will be referred to as a "chip time interval," but it should be understood that the term "modulation time interval" may also be used as needed. Similarly, the data value of the modulation / chip time interval will be referred to as a chip value, and the predetermined pattern / chip sequence will simply be referred to as a predetermined chip sequence.

[0071] In some embodiments, each data symbol may be represented by only a single chip time interval. Therefore, in this case, the data symbol value can simply be the binary chip value of that chip time interval; for example, a data symbol value "0" may be represented by a single chip time interval with a frequency of, for example, 100 kHz, while a data symbol value "1" may be represented by a single chip time interval with a frequency of, for example, 99 kHz. In extreme cases, each mode / predetermined chip sequence may consist of only a single chip time interval, and there are only two possible frequencies. Therefore, in such an example, each mode / predetermined chip sequence may correspond to a specific constant frequency.

[0072] In many embodiments and scenarios, each data symbol can be represented by multiple chip time intervals, and thus by a sequence / pattern of multiple binary chip values ​​for each chip time interval, correspondingly represented by a predetermined chip sequence of multiple constant modulation levels. Therefore, in many embodiments, each data symbol can be represented by a predetermined chip sequence comprising multiple chip time intervals, for example, in many cases not less than 4, 6, 8, 10, or 16 chip time intervals. In this case, each chip time interval can have a constant modulation level representing the binary chip value of that chip time interval; that is, each chip time interval has a binary chip value represented by the frequency or phase of the power transmission signal during that chip time interval.

[0073] Each data symbol value is associated with a predetermined sequence of binary chip values ​​for multiple chip time intervals. Typically, the number of possible predetermined chip sequences is much greater than the number of data symbol values. For example, a binary data symbol value can be represented using a predetermined sequence of chips containing eight chip time intervals; that is, two predetermined chip sequences selected from 256 possible sequences can be used to represent these two data symbol values. Generally, predetermined chip sequences with the lowest cross-correlation are used to represent different data symbol values.

[0074] This method can correspond to direct sequence spread spectrum (DSSS) modulation of the power transmission signal using a suitable chip sequence.

[0075] In this modulation scheme, for at least some data symbol values ​​or consecutive pairs of data symbol values, the constant modulation level can remain unchanged between consecutive data symbols.

[0076] For example, in a scenario where each data symbol is represented by only a single modulation / chip time interval (and therefore each data symbol transmits only one constant modulation level), two or more consecutive data symbols may have the same data symbol value, and thus be represented by the same constant modulation level. Therefore, if one data symbol follows directly after another, the consecutive communication time intervals between different data symbols may have the same constant modulation level. Specifically, during consecutive data symbol periods, the power transmission signal may have the same frequency, and this same frequency remains constant over multiple consecutive modulation / chip time intervals.

[0077] The same situation may occur in scenarios where each data symbol is represented by a predetermined chip sequence of multiple chip time intervals / binary chip values. In such cases, the last chip time interval / binary chip value may be the same as the first chip time interval / binary chip value of the next data symbol. Furthermore, in most scenarios, at least one (usually all) of the predetermined chip sequence includes consecutive chip time intervals that do not change or have different modulation levels. Figure 6 An example of a possible pattern / chip sequence (partial) for two data symbols is shown.

[0078] This method can be considered as applying DSSS modulation to the power transmission signal; that is, a predetermined sequence of binary chip values ​​(each chip corresponding to a chip time interval) can be applied as an FSK or PSK signal to the power transmission signal. This method can specifically encode a predetermined chip pattern / sequence (such as a Barker code or M-sequence) for each data symbol value, which has a very strong autocorrelation peak at zero offset and low autocorrelation at all other offsets. Furthermore, chip patterns / sequences with low cross-correlation can be selected. This method can effectively detect modulated signals even below the noise floor.

[0079] Therefore, the power transmitter, particularly the power transmitter communicator 207, is arranged to transmit data using absolute FSK or PSK modulation. This transmission modulation is non-differential, and the constant modulation level during a chip time interval can depend solely on the binary chip value of that chip time interval. The constant modulation level of one chip time interval can be independent of the constant modulation levels of other chip time intervals. The binary chip value of a given chip time interval can be determined / given solely by the constant modulation level within that chip time interval. It is generally not determined / given by the constant modulation level within any other chip time interval.

[0080] However, although the transmission and modulation are absolutely non-differential modulation, the power receiver is arranged to use differential demodulation.

[0081] Specifically, the power receiver communicator 509 is configured to determine the measured modulation level within each chip time interval. Furthermore, for each (or at least some) chip time intervals, it determines the difference between the measured modulation level within a given chip time interval and the measured modulation level within the immediately preceding chip time interval. The power receiver communicator 509 can then continue to determine the binary chip value of the current chip time interval / chip based on the difference between the measured level within the current chip time interval and the measured level within the previous chip time interval.

[0082] In many embodiments, the power receiver communicator 509 may be specifically arranged to determine the binary chip value of the chip time interval based on the sign of the difference. When using the binary chip value and only two constant modulation levels, the binary chip value can be determined to be a value that matches the constant modulation level in the direction of change of the measured difference.

[0083] For example, in a binary FSK method, where a first binary chip value (e.g., "0") is represented by a first frequency (e.g., 100 kHz) and a second binary chip value (e.g., "1") is represented by a second lower frequency (e.g., 99 kHz), the power receiver communicator 509 can be arranged such that: if the difference indication frequency increases, the binary chip value of a given (chip) binary chip value / chip time interval is determined as the first binary chip value; if the difference indication frequency decreases, the binary chip value of a given (chip) binary chip value / chip time interval is determined as the second binary chip value (i.e., a positive frequency difference corresponds to "0", and a negative frequency difference corresponds to "1").

[0084] In an embodiment where each data symbol is represented by a single chip time interval pattern / predetermined chip sequence, the binary chip value of that chip time interval can be directly used as the data symbol value. In an embodiment where each data symbol value is represented by multiple chip time intervals / chip patterns / predetermined chip sequences, the received binary chip values ​​can be combined to form a received pattern / predetermined chip sequence, which can be compared with stored pattern / predetermined chip sequences of different data symbol values. Therefore, the data symbol value can be determined as the value associated with the pattern / predetermined chip sequence that most closely matches the received pattern / predetermined chip sequence. The degree of matching can be evaluated by performing a correlation operation between the received pattern / predetermined chip sequence and the stored pattern / predetermined chip sequence and selecting the chip sequence with the highest correlation value. The data symbol is then determined as the data symbol value associated with that pattern / predetermined chip sequence. The power receiver communicator 509 can be arranged to determine the data symbol value of a given data symbol as the data symbol value associated with the pattern / predetermined chip sequence that most closely matches the received pattern / predetermined chip sequence of that given data symbol among different pattern / predetermined chip sequences.

[0085] Therefore, the system uses a non-homogeneous approach, where the power transmitter uses an absolute modulation scheme, while the power receiver applies a differential demodulation method.

[0086] This method reflects the inventors' understanding that in many wireless power transmission systems, power transmission exhibits significant inherent inertia, which significantly slows down changes in the operating point of power transmission. In fact, this method reflects the inventors' understanding that in many wireless power transmission systems, this inertia applies not only to the power level / amplitude of the power transmission signal but also to its frequency and phase. Specifically, an instantaneous change in the drive frequency or phase of the drive signal generated by driver 201 does not immediately cause a corresponding change in the induced signal generated at the power receiver. Instead, the signal frequency extracted at the power receiver undergoes a relatively slow change.

[0087] In particular, wireless power transfer systems include significant reactive components that prevent instantaneous changes in energy. This gradual transition occurs not only in the amplitude / power domain but also in the frequency domain (because these domains are closely connected).

[0088] Figure 7 An example of a simulated frequency transition in a wireless power system is shown. The figure illustrates the frequency response of frequency transition 701 relative to modulation applied to drive signal 703. The x-axis represents the number of cycles of the power supply voltage of driver 201 (typically a rectified AC voltage of 100 or 120 kHz). It can be seen that the transition is a rather lengthy process: the frequency change begins in the 5th cycle, and the observed frequency stabilizes approximately 5 cycles after the frequency change. The same is true for the reverse transition, which begins in the 15th cycle.

[0089] This means that, for at least a few power supply voltage cycles, while the power transmitter maintains a constant modulation level / frequency, the observed chip time interval differential modulation will show a value indicating that particular transition, thus showing an absolute frequency value (e.g., if a negative slope in the differential signal results in a logic '1', then the differential modulator on the power transmitter will recognize it as '1' for the first few cycles after the transmitter applies '1').

[0090] The power receiver communicator 509 can determine the modulation level based on the difference between a specific chip time interval and the previous chip time interval, and thus determine the binary chip value for that specific chip time interval. Therefore, the inertia in wireless power transmission systems allows the power transmitter to apply modulation in a conventional manner, such as using one frequency f1 to encode a binary chip value of logic "1" and another frequency f2 to encode a binary chip value of logic "0," while still allowing the power receiver to detect the binary chip value as if using differential modulation, even when encoding a sequence of constant binary chip values.

[0091] This method offers numerous advantages. In particular, differential decoding / demodulation is generally less complex and enables more accurate detection. It especially avoids the need to determine absolute measurements or reference frequencies / phases to ascertain chip data values ​​(bit binary chip values). Furthermore, unlike fully differential modulation schemes (where consecutive identical bit binary values ​​lead to increasing frequency / phase variations / biases), this scheme maintains the modulation frequency / phase closer to the average value. This is particularly important for wireless power transmission where the power transmission signal is modulated, as modulation can affect power transmission operation. Specifically, frequency variations in the power transmission signal cause variations in the transmitted power level (in fact, power control is often achieved by adjusting the (average) frequency of the power transmission signal). This method can mitigate, reduce, or eliminate the disadvantages of differential demodulation while providing the advantages, such as avoiding severe power signal perturbations caused by significant changes in operating frequency.

[0092] This method can be particularly effective for implementations where each data symbol is represented by a pattern / predetermined chip sequence of multiple modulation level / chip time intervals. For example, when using the DSSS method (e.g., more than 4, 6, 8, 10, or 16 modulation level / chip time intervals), each chip time interval is typically relatively short to achieve a reasonable data rate. This communication can provide improved detection and generally results in a lower error rate. It can also typically allow for a given performance to be achieved with a reduced modulation depth (the difference between modulation levels). However, using differential modulation can result in a larger overall deviation in the power transmission signal.

[0093] In many embodiments, each possible binary chip value is associated with a modulation level; for example, each possible binary chip value corresponds to an absolute frequency. For binary communication, one frequency can be assigned to the binary chip value "0," and another frequency can be assigned to the binary chip value "1."

[0094] However, in some embodiments, multiple modulation levels can be associated with a single possible binary chip value. For example, "1" can be represented by any of the frequencies 99kHz, 98kHz, and 97kHz, while "0" can be represented by any of the frequencies 100kHz, 101kHz, and 102kHz.

[0095] In this scenario, the power transmitter communicator 207 can use a method to select between different modulation levels for a given binary chip value. Specifically, when the binary chip value changes, the new modulation level can be set to the modulation level that differs least from the modulation levels representing other binary chip values. For example, when a binary chip value "1" follows a binary chip value "0", the power transmitter communicator 207 can continue to select 99kHz as the modulation level (because this frequency is closest to the frequency representing the binary chip value "1"). Similarly, when a binary chip value "0" follows a binary chip value "1", the power transmitter communicator 207 can continue to select 100kHz as the modulation level (because this frequency is closest to the frequency representing the binary chip value "1").

[0096] Then, for multiple consecutive chip time intervals all having the same binary chip value, the modulation level can remain unchanged. However, if the number of consecutive chip time intervals all having the same binary chip value exceeds a given threshold, the modulation level used to represent said value can be changed to a modulation level that is far removed from the modulation levels of other possible binary chip values. For example, if more than N (e.g., N=3) chip time intervals with a binary chip value of "1" are transmitted consecutively, the power transmitter communicator 207 can change to use a frequency of 98 kHz to represent "1" instead of using a frequency of 99 kHz. After another M (e.g., M=N=3) consecutive chip time intervals, the power transmitter communicator 207 can select the next modulation level; for example, the modulation frequency representing "1" can be set to 98 kHz.

[0097] Therefore, in some embodiments where multiple modulation levels are associated with a single binary chip value, the power transmitter communicator 207 may, in response to detecting that consecutive chip time intervals exceeding a given number / threshold have the same binary chip value / modulation level, change the representation of the binary chip value from one of a plurality of constant modulation levels to another. In many embodiments, this number / threshold may be an integer in the range of 2 to 15, typically 2, 3, or 4.

[0098] Therefore, in some embodiments, the power transmitter communicator 207 can further adjust the frequency along the direction of change to increase the measured difference at the power receiver. This can be done if a sufficiently long sequence of constant chip values ​​exists. Specific examples are as follows: The power transmitter communicator 207 encodes the '0' value by setting the frequency of the power transmission signal to 100 kHz and encodes the '1' value by setting it to 99 kHz. Then, when transmitting six consecutive 1' value sequences, the power transmitter transmits the first three chip values ​​at a frequency of 99 kHz and the last three chip values ​​at a frequency of 98 kHz.

[0099] Figure 8 An example of this is shown.

[0100] This method ensures that the frequency measured at the power receiver continues to shift / change in the desired direction, thereby ensuring that differential demodulation remains effective and preventing the measured frequency from reaching a steady state.

[0101] In some embodiments, the power transmitter communicator 207 is arranged to include an initial binary chip value / constant modulation level before the chip time interval of the mode / predetermined chip sequence that provides the data symbols. The applied modulation scheme may include a start time interval before the chip time interval representing the predetermined chip sequence of data symbols.

[0102] In this case, the power receiver communicator 509 can provide the same method to demodulate the first chip time interval of the predetermined chip sequence, that is, it can determine the frequency / phase difference between the first chip time interval and the start time interval.

[0103] In this scenario, the power transmitter communicator 207 can constrain the constant modulation level applied during the start time interval to be different from the modulation level of the first chip time interval, effectively making the sign / direction of the modulation level change / difference from the start time interval to the first chip time interval the same as the sign / direction of the modulation level change / difference from another binary chip value to the binary chip value of the first chip time interval. Specifically, if the binary chip value of the first chip time interval is "1", the constant modulation level of the start time interval can be set to be the same as the "0" value (or actually another modulation that results in the same direction of change). For example, if the "1" value is represented by a frequency of 99 kHz and the "0" value by a frequency of 100 kHz, the frequency of the start time interval will be set to be higher than 99 kHz, specifically, it can be set to 100 kHz (when the first binary chip value of the pattern / predetermined chip sequence is "1").

[0104] Therefore, when using FSK, the frequency of the start time interval can be set such that the frequency difference between the start time interval frequency and the frequency of the first chip time interval is equal to the frequency difference between the frequency of the opposite binary chip value of the first chip time interval and the frequency of the value of the first chip time interval.

[0105] In some embodiments, as described above, the modulation level during the start time interval can be set to the same value as the modulation level of another binary chip value that is different from the binary chip value of the first chip time interval. However, in other embodiments, it can be set to a different level, specifically a level that differs more significantly from the first chip time interval. For example, in the example above, the frequency of the start time interval can be set not to 100 kHz, but to, for example, 102 kHz. This approach can increase the difference between the start time interval and one or more first chip time intervals. This can improve the detection of the binary chip values ​​of one or more first chip time intervals.

[0106] In some embodiments, a predetermined chip sequence with a constant modulation level may have several consecutive chip time intervals during which the modulation level remains unchanged. This characteristic is common in sequences with low cross-correlation, such as Barker sequences, and is often the case when applying, for example, DSSS.

[0107] In some embodiments, the selected predetermined chip sequence arranges the longest consecutive chip time interval sequence having the same binary chip value / constant modulation level immediately following the start time interval. Thus, after the start time interval (also referred to as the start bit), there follows a sequence of constant modulation levels (e.g., frequencies) that is longer (or at least not shorter) than any other consecutive constant modulation level sequence.

[0108] In many embodiments, this can provide improved communication. Specifically, the inertia of phase / frequency changes in the power transmission signal tends to result in a large initial gradient / rate of change, which then decreases over time. Therefore, the smaller the frequency difference between two consecutive chip time intervals, the longer the sequence of invariant modulation levels (i.e., the longer the time since the last frequency / phase change). This can be compensated for by making the frequency difference between the frequency during the initial time interval and the first chip time interval greater than the frequency difference that occurs during normal communication. As a result, a significant difference can be maintained for a longer period, thus enabling improved communication for longer sequences of invariant modulation levels.

[0109] In practice, a significant challenge when using the described differential DSSS communication method is handling long sequences of constant chips. As previously mentioned, when more than a given number of constant symbols are detected, the power transmitter communicator 207 can further change the modulation frequency along the conversion direction to increase the difference in the measurement. However, this is not always feasible, as it increases the frequency variation, which can lead to fluctuations in the power signal.

[0110] Another problem is detecting the first binary chip value in the chip sequence. The power transmitter communicator 207 applies DSSS modulation in non-differential mode, but due to differential demodulation, it is expected that the first symbol in the chip sequence is the symbol that causes the frequency difference when measured by the power receiver communicator 509.

[0111] To provide robust pseudo-differential DSSS communication, the power transmitter can be arranged to always apply an additional start chip with a modulation direction opposite to the first symbol in the sequence at the beginning of the sequence. Thus, a start chip value within the start time interval can be achieved. The amplitude of this chip can differ from the sequence modulation depth, and in particular, can be selected to produce a greater difference.

[0112] In many practical implementations, the chip sequence contains several consecutive identical chips, the number of which is equal to the sequence order (e.g., depending on the orientation, a fourth-order sequence may include four consecutive '1's or '0's), and this occurs only once, while the length of the other constant portion of the sequence is less than the sequence order. In this case, it may be advantageous for the power transmitter to begin transmission with the longest identical chip sequence.

[0113] In many embodiments, communication can be performed in repeated communication time intervals, which are separated by time intervals in which no data is transmitted from the power transmitter to the power receiver. These time intervals in which no data is transmitted from the power transmitter are also referred to as non-communication time intervals.

[0114] In some embodiments, the duration of the communication time interval may be shorter than (typically much shorter than) the duration of the non-communication time interval. For example, in many embodiments, the duration of the non-communication time interval may be no less than 2, 3, 5, 10, or 25 times the duration of the communication time interval.

[0115] In many embodiments, the frequency during non-communication time intervals can remain substantially constant and, for example, be adjusted only in response to power control error messages. Specifically, this frequency can be set to be the same as one of the modulation frequencies.

[0116] However, in some embodiments, the power transmitter communicator 207 may be arranged to apply a frequency variation to the power transmission signal during non-communication time intervals. The frequency variation can typically be a predetermined / fixed frequency variation, e.g., independent of power transmission operation and / or data received from the power receiver. Furthermore, this frequency variation is determined to have low correlation with frequency patterns / predetermined chip sequences used to represent different data symbols when transmitting such patterns / predetermined chip sequences. In particular, in many embodiments, the correlation between the frequency variation and each of the different patterns / predetermined chip sequences assigned to the data symbols may be lower than the correlation between each of these patterns / predetermined chip sequences and any constant frequency. In some cases, the former may be 2, 4, 6, 10, or 20 times smaller than the latter.

[0117] This frequency variation can typically be arranged to have an average value close to the average of the constant modulation frequency. For example, binary chip values ​​may occur with equal probability and be represented by frequencies f1 (e.g., equal to 100 kHz) and f2 (e.g., equal to 99 kHz). In this case, the frequency variation can be arranged to have an average frequency of (f1 + f2) / 2. As a specific example, the frequency variation can include switching between these constant modulation frequencies based on the probability of using a constant modulation frequency during communication; for example, since binary chip values ​​are typically equal in probability, the frequency during non-communication time intervals can, for example, alternate between modulation frequencies.

[0118] In many embodiments, the duration between frequency changes can be relatively short. For example, in many embodiments, the duration between frequency changes can be the same as the duration of the chip time interval. In some cases, the interval between frequency changes can be no less than 1 / 10 (or 1 / 5) of the duration of the chip time interval and / or no more than 2, 5, or 10 times the duration of the chip time interval.

[0119] In some embodiments, during non-communication time intervals when no communication is performed, the power transmitter may not necessarily set the frequency of the power transmission signal to a constant value corresponding to one of the modulation frequencies, but may instead be arranged to change / jitter the frequency, for example, by switching between different modulation frequencies. This can, for example, provide an average frequency more consistent with the frequency experienced during communication. Furthermore, jitter can be performed during non-communication time intervals, making it less risky for the power receiver communicator 509 to detect the change as corresponding to a data symbol value.

[0120] The inventors have recognized that, in many methods using FSK modulation schemes, it is advantageous for the power transmitter to apply frequency jitter when not communicating. This can improve the stability of the power signal (and consequently the stability of the load power) during communication, as well as the detectability at the power receiver side. Frequency jitter can include switching the power transmission signal frequency between f1 and f2 at appropriate time intervals (e.g., each power cycle, e.g., 100 Hz–120 Hz), thereby generating a recurring …0-1-0-1-0… pattern at the demodulator, causing the cross-correlation pattern at the demodulator to fluctuate around an intermediate value. Therefore, this method allows the demodulator of the power receiver communicator 509 to operate continuously without the risk of detecting frequency jitter as real communication data.

[0121] Figure 9 An example of the results of applying frequency jitter when there is no communication is shown. The figure illustrates the cross-correlation between the unmodulated carrier and the modulation pattern / predetermined chip sequence of the 7th-order Barker code, and the cross-correlation between the frequency-jittered carrier and the same 7th-order Barker code. It can be seen that a significantly reduced / more constant correlation value can generally be achieved. In particular, this method provides good control over the desired frequency difference between successive measurements, rather than random fluctuations caused by noise. In fact, without an absolute reference, the differential reference obtained from the power signal depends on minimum fluctuations. This can significantly increase the risk of false detections, as the probability of high correlation with the stored pattern / predetermined chip sequence increases. However, by introducing intentional frequency jitter, such false detections can be greatly reduced.

[0122] Another advantage of frequency jitter carriers is that lower power signal fluctuations can be achieved between communication and non-communication periods because matching operations can be achieved (e.g., the same average frequency can be achieved).

[0123] It should be understood that, for clarity, the above description has referenced various functional circuits, units, and processors to describe embodiments of the invention. However, it will be apparent that any suitable allocation of functions among different functional circuits, units, or processors can be used without departing from the invention. For example, functions shown to be performed by a separate processor or controller may be performed by the same processor or controller. Therefore, references to specific functional units or circuits are to be considered merely as references to suitable means of providing said functions, and do not indicate a strict logical or physical structure or organization.

[0124] This invention can be implemented in any suitable form, including hardware, software, firmware, or any combination thereof. Optionally, this invention can be implemented at least in part as computer software running on one or more data processors and / or digital signal processors. The various elements and components of embodiments of this invention can be implemented physically, functionally, and logically in any suitable manner. In practice, functionality can be implemented in a single unit, in multiple units, or as part of other functional units. Therefore, this invention can be implemented in a single unit, or it can be physically and functionally distributed among different units, circuits, and processors.

[0125] Although the invention has been described in conjunction with some embodiments, it is not intended to be limited to the specific forms set forth herein. Rather, the scope of the invention is defined only by the claims. Furthermore, although features may appear to be described in conjunction with specific embodiments, those skilled in the art will recognize that various features of the embodiments can be combined according to the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

[0126] Furthermore, although features are listed individually, multiple means, elements, circuits, or method steps can be implemented by, for example, a single circuit, unit, or processor. Additionally, although different features may be included in different claims, these features can be advantageously combined, and the presence of a feature in different claims does not imply that such a combination is infeasible and / or disadvantageous. Moreover, the inclusion of a feature in one class of claims does not imply a limitation on that class, but rather indicates that the feature is equally applicable to other claim classes. The inclusion of a feature in a dependent claim of an independent claim does not imply a limitation on that independent claim, but rather indicates that the feature is equally applicable to other independent claims. Furthermore, the order of features in a claim does not imply that these features must be performed in any particular order; in particular, the order of steps in a method claim does not imply that these steps must be performed in that order. Rather, these steps can be performed in any suitable order. Furthermore, singular references do not exclude plural references. Therefore, references to “a,” “an,” “first,” “second,” etc., do not exclude plural references. Reference numerals in the claims are provided as illustrative purposes only and should not be construed as limiting the scope of the claims in any way.

[0127] (Binary) chip values ​​can also be referred to as data values. A predetermined chip sequence (of one or more binary chip values) can also be referred to as a pattern (of one or more data or chip values). Chip time intervals can also be referred to as modulation time intervals. Such substitutions are permissible throughout the text, including the claims. Therefore, the described method can also support the following descriptions / definitions of embodiments: Example: Example 1: A power receiver (105) for wirelessly receiving power from a power transmitter (101) via electromagnetic power transmission signals, the power receiver (105) comprising: The input circuit (107, 501) includes a receiver coil (107) arranged to extract power from the power transmission signal to generate an induced power signal; A power receiver controller (501) is arranged to control the operation of the power receiver (105) based on data received from the power transmitter (101); A communicator (509) is arranged to receive data modulated onto the power transmission signal using a modulation scheme from the power transmitter (101), wherein each data symbol value is represented by a different mode of at least one data value, each data value is represented by a constant modulation level in a modulation time interval, each constant modulation level being at least one of a constant frequency and a constant phase of the power transmission signal during the modulation time interval, the constant modulation level remaining constant between some consecutive modulation time intervals; The communicator (509) is arranged as follows: For each of at least some modulation time intervals, the difference between the measured modulation level within each modulation time interval and a previously measured modulation level, wherein the previously measured modulation level is the modulation level measured within the modulation time interval immediately preceding each modulation time interval, and the received data value within each modulation time interval is determined based on the difference; and The data symbol value is determined by comparing the reception pattern formed by the received data values ​​with the different patterns.

[0128] Example 2: The power receiver according to Example 1, wherein the different modes include only one modulation time interval.

[0129] Example 3: The power receiver according to Example 1, wherein the different modes include at least four modulation time intervals.

[0130] Example 4: A power receiver according to any of the preceding embodiments, wherein the modulation scheme includes a start time interval prior to the modulation time interval of the mode for the data symbol; and wherein the communicator (509) is arranged to determine a previously measured modulation level within the initial modulation time interval of the mode for the data symbol as the modulation level measured within the start time interval.

[0131] Example 5: According to the power receiver described in Example 4, the constant modulation level during the start time interval is constrained to be different from the constant modulation level during the initial modulation time interval.

[0132] Example 6: A power receiver according to Example 4 or 5, wherein the different modes are arranged such that the longest consecutive modulation time interval sequence having the same data value immediately follows the start time interval.

[0133] Example 7: A power receiver according to any of the preceding embodiments, wherein the modulation scheme includes a plurality of constant modulation levels associated with at least a first data value, and wherein, in response to the number of consecutive modulation time intervals having a first constant modulation level among the plurality of constant modulation levels exceeding a threshold, the first data value is changed from being represented by the first constant modulation level to being represented by a second constant modulation level among the plurality of constant modulation levels.

[0134] Example 8: The power receiver according to Example 7, wherein the difference between the first constant modulation level and the constant modulation level associated with a data value different from the first data value is less than the difference between the second constant modulation level and the constant modulation level connected to the different data value.

[0135] Example 9: A power receiver according to any of the foregoing embodiments, wherein the data values ​​of the different modes are binary data values.

[0136] Example 10: A power transmission system including a power transmitter (101) that provides power to a power receiver (105) according to any of the preceding embodiments, the power transmitter (101) comprising: Output circuits (203, 103) include a transmitter coil (103) arranged to generate the power transmission signal in response to a drive signal applied to the output circuits (203, 103); A driver (201) is arranged to generate the drive signal; A first communicator (207) is configured to transmit data to a power receiver (105) by modulating the power transmission signal using the modulation scheme in which each data symbol value is represented by a different mode of at least one data value, each data value is represented by a constant modulation level in a modulation time interval, each constant modulation level being at least one of a constant frequency and a constant phase of the power transmission signal during the modulation time interval, the constant modulation level remaining constant between some consecutive modulation time intervals.

[0137] Example 11: The power transmission system according to Example 10, wherein each constant modulation level is a constant frequency, and the first communicator (207) is arranged to transmit data to the power receiver (105) during a communication time interval and to apply a frequency variation to the power transmission signal during the time interval between the communication time intervals.

[0138] Example 12: The power transmission system according to Example 11, wherein the first communicator (207) is arranged to apply a frequency variation, the frequency variation being less correlated with each of the different frequency modes than any constant frequency is correlated with each of the different frequency modes.

[0139] Example 13: An operation method for a power receiver (105) to wirelessly receive power from a power transmitter (101) via an electromagnetic power transmission signal, the power receiver comprising: The input circuit (107, 501) includes a receiver coil (107) that extracts power from the power transmission signal to generate an induced power signal; A power receiver controller (501) is arranged to control the operation of the power receiver (105) based on data received from the power transmitter (101); A communicator (509) is arranged to receive data modulated onto the power transmission signal using a modulation scheme from the power transmitter (101), wherein each data symbol value is represented by a different mode of at least one data value, each data value is represented by a constant modulation level in a modulation time interval, each constant modulation level being at least one of a constant frequency and a constant phase of the power transmission signal during the modulation time interval, the constant modulation level remaining constant between some consecutive modulation time intervals; The method includes the communicator (509) performing the following steps: For each of at least some modulation time intervals, a difference is determined between the measured modulation level within each modulation time interval and a previously measured modulation level, the previously measured modulation level being the modulation level measured within the modulation time interval immediately preceding each modulation time interval, and the received data value within each modulation time interval is determined based on the difference; and The data symbol value is determined by comparing the reception pattern formed by the received data values ​​with the different patterns.

Claims

1. A power receiver (105) for wirelessly receiving power from a power transmitter (101) via an electromagnetic power transmission signal, the power receiver (105) comprising: The input circuit (107, 501) includes a receiver coil (107) arranged to extract power from the power transmission signal to generate an induced power signal; A power receiver controller (501) is arranged to control the operation of the power receiver (105) based on data received from the power transmitter (101); A communicator (509) is arranged to receive data symbols transmitted from the power transmitter (101), each data symbol having a data symbol value and modulated onto the power transmission signal using a modulation scheme in which each data symbol value is associated with a different predetermined sequence of one or more binary chip values, each binary chip value being represented by a constant modulation level in a chip time interval, each constant modulation level being at least one of a constant frequency of the power transmission signal and a constant phase of the power transmission signal, the constant modulation level remaining constant between a number of consecutive chip time intervals; The communicator (509) is arranged as follows: For each of at least some chip time intervals, determine the difference between the measured modulation level in the chip time interval and the measured modulation level in the immediately preceding chip time interval, and determine the received binary chip value in the chip time interval based on the difference; and The data symbol value is determined by comparing the received chip sequence formed from the received binary chip values ​​with the different predetermined chip sequences.

2. The power receiver according to claim 1, wherein, The different predetermined chip sequences each include only one binary chip value.

3. The power receiver according to claim 1, wherein, The different predetermined chip sequences include no fewer than four binary chip values.

4. The power receiver according to any one of the preceding claims, wherein, The modulation scheme includes a start time interval preceding a chip time interval for a predetermined chip sequence of data symbols; and wherein the communicator (509) is arranged to determine a previously measured modulation level within the initial chip time interval of the predetermined chip sequence of the data symbols as a modulation level measured within the start time interval.

5. The power receiver according to claim 4, wherein, The constant modulation level during the start time interval is constrained to be different from the constant modulation level during the initial chip time interval.

6. The power receiver according to claim 4 or 5, wherein, The different predetermined chip sequences are arranged such that the longest consecutive chip time interval sequence with the same binary chip value immediately follows the start time interval.

7. The power receiver according to any one of the preceding claims, wherein, The modulation scheme includes a plurality of constant modulation levels associated with at least a first binary chip value, wherein, in response to the number of consecutive chip time intervals having the first constant modulation level among the plurality of constant modulation levels exceeding a threshold, the first binary chip value is changed from being represented by the first constant modulation level to being represented by a second constant modulation level among the plurality of constant modulation levels.

8. The power receiver according to claim 7, wherein, The difference between the first constant modulation level and the constant modulation level associated with a binary chip value that is different from the first binary chip value is less than the difference between the second constant modulation level and the constant modulation level associated with the different binary chip value.

9. A power transmission system comprising a power receiver according to any one of the preceding claims and a power transmitter (101) for providing power to the power receiver (105), the power transmitter (101) comprising: Output circuits (203, 103) include a transmitter coil (103) arranged to generate the power transmission signal in response to a drive signal applied to the output circuits (203, 103); A driver (201) is arranged to generate the drive signal; A first communicator (207) is configured to transmit data to a power receiver (105) by modulating the power transmission signal using the modulation scheme in which each data symbol value is represented by a different predetermined sequence of at least one binary chip value, each binary chip value is represented by a constant modulation level in a chip time interval, each constant modulation level being at least one of a constant frequency and a constant phase of the power transmission signal during the chip time interval, the constant modulation level remaining constant between a number of consecutive chip time intervals.

10. The power transmission system according to claim 9, wherein, Each constant modulation level is a constant frequency, and the first communicator (207) is arranged to transmit data to the power receiver (105) during communication time intervals and to apply frequency variations to the power transmission signal during time intervals between the communication time intervals.

11. The power transmission system according to claim 10, wherein, The first communicator (207) is arranged to apply a frequency variation that is less correlated with each frequency mode of the different predetermined chip sequences than any constant frequency is correlated with each frequency mode of the different predetermined chip sequences.

12. A method of operation for a power receiver (105) to wirelessly receive power from a power transmitter (101) via an electromagnetic power transmission signal, the power receiver comprising: The input circuit (107, 501) includes a receiver coil (107) that extracts power from the power transmission signal to generate an induced power signal; A power receiver controller (501) is arranged to control the operation of the power receiver (105) based on data received from the power transmitter (101); A communicator (509) is arranged to receive data symbols transmitted from the power transmitter (101), each data symbol having a data symbol value and modulated onto the power transmission signal using a modulation scheme in which each data symbol value is associated with a different predetermined sequence of one or more binary chip values, each binary chip value being represented by a constant modulation level in a chip time interval, each constant modulation level being at least one of a constant frequency of the power transmission signal and a constant phase of the power transmission signal, the constant modulation level remaining constant between a number of consecutive chip time intervals; The method includes the communicator (509) performing the following steps: For each of at least some chip time intervals, determine the difference between the measured modulation level in the chip time interval and the measured modulation level in the immediately preceding chip time interval, and determine the received binary chip value in the chip time interval based on the difference; and The data symbol value is determined by comparing the received chip sequence formed from the received binary chip values ​​with the different predetermined chip sequences.

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