Wireless Power Transmission System

Abstract

The power transmitter 101 wirelessly supplies power to the power receiver 105 via a power transmission signal generated by the power transmission coil 103. During power transmission, the driver 201 generates the power transmission signal to adopt a recurring time frame consisting of a power transmission time interval and a communication time interval during which the power transmission signal is off. The communication driver 209 generates a communication drive signal for the communication coil 207 to generate a communication carrier signal. Communication between the power transmitter and the power receiver is achieved by modulating the communication carrier signal during the communication time interval. The communication driver 205 generates the communication carrier signal to exist during the recurring time frame, except for timing gaps that are 50% or less of the duration of the power transmission time interval. The set of timing gaps consists of a predetermined pattern of multiple timing gaps. The power receiver extracts power from the communication carrier signal and synchronizes its operation based on the timing gaps.

Description

[Technical Field]

[0001] The present invention relates to the operation of wireless power transfer systems. [Background technology]

[0002] Most current electrical products require dedicated electrical contacts to receive power from an external power source. However, this tends to be impractical, requiring the user to physically insert a connector or otherwise establish physical electrical contact. Power requirements also typically vary widely, and currently most devices are provided with dedicated power sources, resulting in a typical user having numerous different power sources, each dedicated to a specific device. However, while the use of an internal battery can avoid the need for a wired connection to a power source during use, this only provides a partial solution, as the battery requires recharging (or replacement). Additionally, using a battery can substantially increase the weight and potential cost and size of the device.

[0003] To provide a significantly improved user experience, it has been proposed to use a wireless power source in which power is inductively transferred from a transmitter inductor in the power transmitting device to a receiver coil in the individual device.

[0004] Power transfer via magnetic induction is a well-known concept and is mostly applied to transformers with tight coupling between the primary transmitter inductor / coil and the secondary receiver coil. By separating the primary transmitter coil and secondary receiver coil between the two devices, wireless power transfer between them becomes possible based on the principle of a loosely coupled transformer.

[0005] Such a configuration allows for wireless power transmission to a device without the need for a wired or physical electrical connection. Indeed, a device can simply be placed adjacent to or on top of the transmitter coil for external recharging or powering. For example, the power transmitter can be configured to have a horizontal surface onto which a device can simply be placed to receive power.

[0006] Furthermore, such wireless power transmission configurations can be advantageously designed so that the power transmitter can be used with a range of power receiving devices. In particular, a wireless power transmission approach known as the Qi standard has been defined and is currently being further developed. This approach allows power transmitter devices that meet the Qi standard to be used with power receiver devices that meet the Qi standard, without the need for them to be from the same manufacturer or proprietary to each other. The Qi standard also includes several features that allow operation to be tailored to specific power receiving devices (e.g., depending on a specific power drain).

[0007] The Qi standard is developed by the Wireless Power Consortium and more detailed information can be found, for example, on their website (http: / / www.wirelesspowerconsortium.com / index.html), in particular the specifications that define it.

[0008] The Wireless Power Consortium has been developing the Ki standard (also known as the Cordless Kitchen standard), which builds on the Qi standard and aims to provide safe, reliable, and efficient wireless power transmission to kitchen appliances. Ki supports much higher power levels, up to 2.5KW.

[0009] Many systems, particularly Qi systems, may use load modulation in communication from a power receiver to a power transmitter. In load modulation, the load of the power transmission signal varies depending on the data being transmitted. However, detecting such load modulation can be difficult if the power transmission load of the power transmission signal also fluctuates. Similarly, communication from a power transmitter to a power receiver can be achieved by modulating the power transmission signal (e.g., amplitude modulation or frequency modulation), but interference with such modulation can be caused by fluctuations in the parameters of the power transmission signal, for example, due to load fluctuations.

[0010] Some systems have proposed using a completely independent communication approach. Specifically, the Ki wireless power transfer system can establish a bidirectional communication link using the Near Field Communication (NFC) standard. Communication is performed at short time intervals during the power transfer phase to avoid or reduce interference between power transfer and communication. The power receiver is configured to detect the NFC carrier to perform communication during the short time intervals.

[0011] During power transfer operation, the power receiver extracts power for the load from the power transfer signal. In many cases, the extracted power is also used to power the power receiver's own functions, such as a processing unit or user interface. However, such an approach requires additional functionality and may not be optimal in all scenarios. Summary of the Invention [Problem to be solved by the invention]

[0012] Accordingly, improved operations for wireless power transfer systems would be advantageous, particularly approaches that allow for increased flexibility, reduced cost, reduced complexity, improved communication, additional functionality, and / or improved performance. [Means for solving the problem]

[0013] Accordingly, the Invention seeks to preferably mitigate, reduce or eliminate one or more of the above mentioned disadvantages singly or in any combination.

[0014] According to one aspect of the present invention, there is provided a power transmitter for wirelessly supplying power to a power receiver via an inductive power transmission signal, the power transmitter comprising: a power transmission coil configured to generate the power transmission signal; a power transmission driver configured to generate the power transmission drive signal for the power transmission coil, the power transmission driver configured to generate the power transmission drive signal to adopt a repeating time frame including at least a power transmission time interval and a communication time interval during a power transmission phase, the power transmission driver configured to generate the power transmission drive signal during the power transmission time intervals and not generate the power transmission drive signal during the communication time intervals; a communications coil configured to generate a communications carrier signal; a communications driver configured to generate a communications drive signal for the communications coil to generate the communications carrier signal; and a communications unit configured to communicate with the power receiver using modulation of the communications carrier signal during the communication time intervals, the communications driver configured to generate the communications drive signal to occur during the communications time intervals and during the power transmission time intervals except during a set of timing gaps during which the communications drive signal is not generated, the total duration of the set of timing gaps being less than or equal to 50% of the duration of the power transmission time intervals, the set of timing gaps comprising a predetermined pattern of a plurality of timing gaps.

[0015] The present invention can provide improved performance in many embodiments and can provide overall improved power transfer operation in many systems and embodiments. For example, improved operation and communication are achieved in many embodiments. This approach allows for efficient, low-complexity synchronization between a power transmitter and a power receiver. This approach can provide an improved secondary power path from a power transmitter to a power receiver in many scenarios, thereby improving transmission at low power levels. In many embodiments, this approach can reduce the complexity of the power receiver, and in many cases can eliminate the need for the power receiver to include functionality for extracting power from the power transfer signal for internal power receiving circuitry.

[0016] This approach allows for increased power extraction from the communications carrier signal while still allowing for efficient synchronization and communication.

[0017] This approach also, in many embodiments, allows for a more continuous extraction of power from the communications carrier signal, thereby reducing fluctuations such as ripple caused by the power extraction, resulting in a more stable communications carrier signal, further improving load modulation.

[0018] The use of a set of timing gaps consisting of a predetermined pattern of timing gaps allows for improved operation and / or ease of implementation and / or operation in many embodiments, particularly in many scenarios by allowing for more accurate timing gap detection, leading to improved synchronization operation and increased performance.

[0019] In many embodiments, the duration of the communication time interval is 5%, 10%, or 20% or less of the duration of the time frame. In many embodiments, the duration of the power transmission time interval is 70%, 80%, or 90% or more of the duration of the recurring time frame. The combined / total duration of the timing gaps, in many embodiments, does not exceed 1%, 2%, 5%, or 10% of the duration of the power transmission time interval and / or the duration of the recurring time frame.

[0020] The modulation of the communication carrier signal during the communication time interval can be by load modulation of the carrier from the power receiver to the power transmitter and / or amplitude modulation from the power transmitter to the power receiver. The communication can be an NFC communication.

[0021] A timing gap may also be called a synchronization time interval, a timing time interval, or a synchronization gap.

[0022] The power transmitter can include a synchronizer for synchronizing the timing of the set of timing gaps to the recurring time interval. Each time interval can have a fixed / predetermined / constant time offset relative to (e.g., relative to the start and / or end of) the recurring time frame. The power transmitter can include a synchronizer for synchronizing the timing of the set of timing gaps to the timing of at least one of the power transmission time interval and the communication time interval.

[0023] The power transfer driver can be configured to generate the power transfer drive signal, and thus the power transfer signal, to have a non-zero amplitude during the power transfer time interval and a zero amplitude during the communication time interval.

[0024] The communications driver can be configured to generate the communications drive signal, and therefore the communications carrier signal, to have a non-zero amplitude other than during the timing gap. The communications driver can be configured to generate the communications drive signal, and therefore the communications carrier signal, to have an amplitude variation of less than 10% of the average amplitude outside the timing gap. The communications driver can be configured to generate the communications drive signal to have zero amplitude during the timing gap.

[0025] In accordance with an optional feature of the invention, the communications driver may be configured to generate the communications drive signal such that at least a first timing gap of the set of timing gaps has a fixed time offset relative to the timing of the power transfer time interval.

[0026] This may allow for improved operation and / or ease of implementation and / or operation in many embodiments.

[0027] In some embodiments, the communication driver can be configured to generate the communication drive signal such that at least a first timing gap of the set of timing gaps has a fixed time offset relative to the timing of the communication time interval.

[0028] In some embodiments, the communication driver can be configured to generate the communication drive signal such that at least a first timing gap of the set of timing gaps has a fixed time offset relative to the timing of the recurring time frame.

[0029] In accordance with an optional feature of the invention, a set of timing gaps is included in the power transfer time interval.

[0030] This may allow for improved operation and / or ease of implementation and / or operation in many embodiments.

[0031] In accordance with an optional feature of the invention, the predetermined pattern is a pattern of timing gaps having the same duration and having the same time difference between successive timing gaps of the same recurring time frame.

[0032] This may allow for improved operation and / or ease of implementation and / or operation in many embodiments.

[0033] In accordance with an optional feature of the invention, the predetermined pattern is selected from a plurality of predetermined patterns.

[0034] This may allow for improved operation and / or ease of implementation and / or operation in many embodiments.

[0035] According to an optional feature of the invention, the power transmission driver is configured to be powered by a time-varying power supply signal, and the communication driver is configured to synchronize timing of the set of timing gaps to the varying power supply signal.

[0036] This may allow for improved operation and / or ease of implementation and / or operation in many embodiments.

[0037] The time-varying power supply signal is generated from a mains power supply, for example directly or by rectification of an AC mains power signal. The repeating time frames can be synchronized to the time-varying power supply signal / mains power supply. The power transfer driver can be configured to generate the time-varying drive signal during the power transfer time interval, and the communication driver can be configured to synchronize the timing of a set of timing gaps to the time-varying drive signal.

[0038] In accordance with an optional feature of the invention, the communications driver is configured to synchronize the end of a timing gap of the set of timing gaps with the end of the power transfer time interval.

[0039] This may allow for improved operation and / or ease of implementation and / or operation in many embodiments.

[0040] In accordance with an optional feature of the invention, the power transmitter is configured to exchange configuration messages with the power receiver, the configuration messages including an indication of a characteristic of at least one timing gap of the plurality of timing gaps.

[0041] This may allow for improved operation and / or ease of implementation and / or operation in many embodiments. The configuration message is an NDEF message in NFC communication.

[0042] In accordance with an optional feature of the invention, the combined duration of the timing gaps is less than or equal to 5% of the duration of the power transfer time interval.

[0043] According to one aspect of the present invention, there is provided a power receiver for wirelessly receiving power from a power transmitter via an electromagnetic power transmission signal, the power transmission signal employing a recurring time frame including at least a power transmission time interval and a communication time interval, the power transmission signal being present during the power transmission time interval and absent during the communication time interval, the power receiver comprising: an inductive power extraction element configured to extract power from the power transmission signal during the power transmission time interval of a power transmission phase; a communications coil for receiving a received communications carrier signal, the communications carrier signal being present during the communication time interval and during the power transmission time interval except during a set of timing gaps during which the communications carrier signal is not present, the total duration of the timing gaps being 50% or less of the duration of the power transmission time interval; a communications unit configured to communicate with the power transmitter using modulation of the communications carrier signal during the communication time interval; and a synchronizer configured to synchronize operation of the power receiver to timing of the set of timing gaps, the set of timing gaps consisting of a predetermined pattern of a plurality of timing gaps.

[0044] This may enable improved operation and / or ease of implementation and / or operation in many embodiments. In many scenarios, a low-complexity and / or low-cost power receiver may be provided. In many scenarios, this approach may reduce or avoid the need for circuitry to extract power from the power transmission signal for internal power receiver functions.

[0045] According to one aspect of the present invention, there is provided a wireless power transmission system including the power transmitter and power receiver described above.

[0046] According to one aspect of the present invention, there is provided a method of operating a power transmitter that wirelessly supplies power to a power receiver via an inductive power transmission signal, the method comprising the steps of: generating a power transmission signal by a power transmission coil; generating a power transmission drive signal for the power transmission coil, wherein the drive signal during a power transmission phase is generated to use a repeating time frame including at least a power transmission time interval and a communication time interval, and the power transmission drive signal is generated to be present during the power transmission time interval but not during the communication time interval; generating a communication carrier signal by a communication coil; generating a communication drive signal for the communication coil to generate the communication carrier signal; and communicating with the power receiver using modulation of the communication carrier signal during the communication time interval, wherein the communication drive signal is generated to be present during the communication time interval and the power transmission time interval except during a set of timing gaps during which the communication drive signal is not generated, the total duration of the set of timing gaps being less than or equal to 50% of the duration of the power transmission time interval, and the set of timing gaps including a predetermined pattern of a plurality of timing gaps.

[0047] According to one aspect of the present invention, there is provided a method of operating a power receiver that wirelessly receives power from a power transmitter via an electromagnetic power transmission signal, the power transmission signal using a recurring time frame including at least a power transmission time interval and a communication time interval, the power transmission signal being present during the power transmission time interval but not during the communication time interval, the method comprising the steps of: extracting power from the power transmission signal during the power transmission time interval of a power transmission phase; receiving a communication carrier signal with a communication coil, the communication carrier signal being present during the communication time interval and the power transmission time interval except for a set of timing gaps during which the communication carrier signal is not present, the total duration of the timing gaps being less than or equal to 50% of the duration of the power transmission time interval; communicating with the power transmitter using modulation of the communication carrier signal during the communication time interval; and synchronizing operation of the power receiver to timing of the set of timing gaps, the set of timing gaps including a predetermined pattern of a plurality of timing gaps.

[0048] These and other aspects, features and advantages of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. [Brief explanation of the drawings]

[0049] Embodiments of the present invention will now be described, by way of example only, with reference to the drawings in which: [Figure 1] FIG. 2 illustrates an example of elements of a power transfer system according to some embodiments of the present invention. [Figure 2] FIG. 1 illustrates an example of elements of a power transmitter according to some embodiments of the present invention. [Figure 3] FIG. 1 illustrates an example of elements of a power receiver according to some embodiments of the present invention. [Figure 4] 1 illustrates an example time frame for a wireless power transfer system according to some embodiments of the present invention. [Figure 5] 1A and 1B are diagrams showing examples of a power transmission signal and a communication carrier signal in a wireless power transmission system. [Figure 6] 1A and 1B are diagrams illustrating examples of power transmission signals and communication carrier signals in a wireless power transmission system according to some embodiments of the present invention. [Figure 7] FIG. 2 is a diagram showing an example of elements of a power transmission path in a wireless power transmission operation. [Figure 8] 1A and 1B are diagrams illustrating examples of power transmission signals and communication carrier signals in a wireless power transmission system according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0050] The following description focuses on embodiments of the invention applicable to wireless power transfer systems that utilize a power transfer approach such as that known from the Qi standard, however, it will be understood that the invention is not limited to this application and may be applied to many other wireless power transfer systems.

[0051] 1 illustrates an example of a power transfer system according to some embodiments of the present invention. The power transfer system includes a power transmitter 101 including (or coupled to) a transmitter coil / inductor 103. The system further includes a power receiver 105 including (or coupled to) a receiver coil / inductor 107.

[0052] The system provides an electromagnetic power transfer signal capable of inductively transferring power from a power transmitter 101 to a power receiver 105. Specifically, the power transmitter 101 generates an electromagnetic signal, which is propagated as magnetic flux by a transmitter coil or inductor 103. The power transfer signal may correspond to an electromagnetic power transfer component representing the transfer of energy from the power transmitter to the power receiver, and may be considered to correspond to the component of the generated electromagnetic field that transfers power from the power transmitter to the power receiver. For example, if there is no load on the receiver coil 107, no power is extracted by the power receiver from the generated electromagnetic field (apart from losses). In such a scenario, driving the transmitter coil 103 can generate an electromagnetic field of potentially high field strength, but the power level of the power transfer signal (apart from losses) would be zero. In some situations where a foreign object is present, the power transfer signal can be considered to include a component corresponding to power transfer to the foreign object, and therefore the power transfer signal can be considered to correspond to power extracted from the electromagnetic field generated by the power transmitter.

[0053] The power transmission signal may typically have a frequency between about 20 kHz and about 500 kHz, and for Ki-compatible systems, may typically have a frequency in the range of 20 kHz to 80 kHz. The transmitter coil 103 and the receiving coil 107 are loosely coupled, and thus the receiving coil 107 picks up (at least a portion of) the power transmission signal from the power transmitter 101. Thus, power is transmitted from the power transmitter 101 to the power receiver 105 via wireless inductive coupling from the transmitter coil 103 to the receiving coil 107. While the term power transmission signal is primarily used to refer to the induction signal / magnetic field (magnetic flux signal) between the transmitter coil 103 and the receiving coil 107, it will be understood that, equivalently, it may also be considered and used to refer to an electrical signal supplied to the transmitter coil 103 or picked up by the receiving coil 107.

[0054] In an embodiment, power receiver 105 is specifically a power receiver that receives power via receiver coil 107. However, in other embodiments, power receiver 105 may include a metallic element, such as a metallic heating element, where the power transmission signal directly induces eddy currents that result in direct heating of the element. Consequently, the power receiver may load the power transmission signal by including an inductive power extraction element, specifically a power extraction coil or an electrical (e.g., heating) element in which a current is induced by the power transmission signal.

[0055] The system is configured to transmit significant power levels, specifically the power transmitter can support power levels of 50 W, 100 W, 500 W or even greater than 1 kW. For example, for Ki-type applications, power transfer is often greater than 100 W, and for very high power applications, it can exceed 2500 W.

[0056] The operation of the power transmitter 101 and the power receiver 105 will be described below with particular reference to embodiments that generally conform to the specifications being developed by the Wireless Power Consortium (except for amendments and extensions described (or consequential) herein). In particular, the power transmitter 101 and the power receiver 105 conform to or are substantially compatible with elements of the Ki standard.

[0057] Many wireless power transfer systems, particularly high-power systems such as Ki, utilize resonant power transfer in which the transmitter coil 103 is part of a resonant circuit, and typically the receiver coil 107 is also part of the resonant circuit. In many embodiments, the resonant circuit may be a series resonant circuit, such that the transmitter coil 103 and receiver coil 107 may be coupled in series with corresponding resonant capacitors. The use of a resonant circuit tends to provide more efficient power transfer.

[0058] FIG. 2 illustrates elements of the power transmitter 101, and FIG. 3 illustrates elements of the power receiver 105 of FIG. 1 in more detail.

[0059] The power transmitter 101 has a driver 201 capable of generating a drive signal that is supplied to a transmitter coil 103, which in turn generates an electromagnetic power transfer signal that provides power transfer to a power receiver 105. The power transfer signal is provided at least during a power transfer time interval of a power transfer phase.

[0060] The driver 201 may comprise an output circuit in the form of an inverter, typically formed by driving a full or half bridge, as is well known to those skilled in the art.

[0061] The power transmitter 101 further includes a power transmitter controller 203 configured to control the operation of the power transmitter 101 according to a desired operating principle. In particular, the power transmitter 101 may include many of the functions necessary to perform power control according to the Qi standard.

[0062] The power transmitter controller 203 is particularly configured to control the generation of the drive signal by the driver 201 and is particularly able to control the power level of the drive signal and therefore the level of the generated power transmission signal. The power transmitter controller 203 comprises a power loop controller that controls the power level of the power transmission signal in response to power control messages received from the power receiver 105 during a power control phase.

[0063] To receive data and messages from the power receiver 105, the power transmitter 101 comprises a first communicator 205 configured to receive data and messages from the power receiver 105 and to transmit data and messages to the power receiver 105 (as will be appreciated by those skilled in the art, a data message may provide one or more bits of information).

[0064] In this approach, communication is performed by modulating a communication carrier signal generated by the first communication coil 207. The power transmitter specifically includes a communication driver 209 coupled to the first communication coil 207. The communication driver 209 is configured to generate a communication drive signal that is supplied to the first communication coil 207 to generate the communication carrier signal. The communication driver 209 can typically be configured to generate a communication drive signal / communication carrier signal having a frequency significantly different from that of the power transmission drive signal / power transmission signal. In many embodiments, the frequency of the communication carrier signal can be 10 times or more, 100 times or more, or 500 times or more the frequency of the power transmission signal. In many embodiments, the frequency of the communication drive signal / communication carrier signal is no less than 500 kHz, 1 MHz, or 10 MHz. In particular, for NFC implementations, the communication carrier signal frequency is 13.56 MHz.

[0065] The first communicator 205 is coupled to the communication driver 209 and configured to control it to modulate a communication drive signal / communication carrier signal to transmit data to the power receiver (references to the communication drive signal below also include implicit references to the communication carrier signal, where appropriate).

[0066] The modulation is illustratively amplitude modulation of the communication drive signal, specifically binary communication using Amplitude Shift Keying (ASK), although it will be appreciated that other approaches may be used in other embodiments, such as phase modulation or frequency modulation of the communication drive signal.

[0067] In some embodiments, the first communicator 205 can receive, for example, data to be transmitted to the power receiver from the power transmitter controller 203 and, in response, generate a control modulation signal that is provided to the communication driver 209. The control modulation signal can be, for example, a binary signal that corresponds to the data to be transmitted, and the communication driver 209 can be configured to generate the communication drive signal to have a corresponding amplitude variation.

[0068] In communication from the power receiver to the power transmitter, the modulation of the communication drive signal can be load modulation. The power receiver can be configured to modulate the power transmission signal by varying the load of the power transmission signal generated by the transmitting coil 103 according to the data to be transmitted. The first communicator 205 can be configured to sense fluctuations in the voltage and / or current of the transmitting coil 103 and demodulate the load modulation based on these. Those skilled in the art will be familiar with the principles of load modulation, so it will not be described in further detail.

[0069] In many embodiments, the communication may conform to Near Field Communication (NFC) standards, and the power receiver may specifically include NFC functionality. In many embodiments, the first communicator 205, the communication driver 209, and the first communication coil 207 may implement (at least) the functionality of an NFC reader. Thus, in many embodiments, the communication drive signal / communication carrier signal is a 13.56 MHz signal at a constant level (excluding modulation).

[0070] In the following description, we will focus on an example in which the communication between the power transmitter and the power receiver is NFC communication, and more specifically, the modulation of the NFC carrier in the direction from the power transmitter to the power receiver is amplitude shift keying (ASK), and the modulation of the NFC carrier in the direction from the power receiver to the power transmitter is load modulation.

[0071] 1-3, communication is performed in a communication time interval during the power transfer phase. Specifically, the transmitter controller 203 can configure / implement a synchronizer 206 configured to synchronize the first communicator 205 such that communication operations (typically both data reception and transmission) are performed in (typically only in) the communication time interval of the power transfer phase, i.e., the time interval allocated for communication.

[0072] This makes it possible to significantly improve communication performance.

[0073] As described in more detail below, this approach utilizes a time-division approach in the power transfer phase, which allows operations such as foreign object detection and communication and power transfer to be performed at different time intervals, thereby significantly reducing interference between them (specifically, the impact of power transfer on foreign object detection and communication).

[0074] Specifically, in a wireless power transfer system, the power transfer signal follows a repeating time frame that includes at least one power transfer time interval and one communication time interval.

[0075] The power transmitter can be configured to turn off the power transmission signal during the communication time interval, and the power receiver can be configured in some embodiments to disconnect the load during the power reduction time interval.

[0076] The power transmitter (and typically the power receiver) can then arrange for one or more operations (functions, processes, procedures) to be performed during the communication time interval, i.e., the execution of one or more operations of the power transmitter can be synchronized to occur during the communication time interval. For example, foreign object detection and communication can typically be synchronized to occur during the communication time interval. In this way, the impact of power transmission and power transmission signals on predetermined operations, specifically foreign object detection and communication, can be reduced, and often minimized.

[0077] FIG. 3 shows some exemplary elements of the power receiver 105.

[0078] The receiver coil 107 is coupled to a power receiver controller 301, which couples the receiver coil 107 to a load 303 via a switch 305 (i.e., a switchable load 305). The power receiver controller 301 includes a power control path that converts the power extracted by the receiver coil 107 into a supply suitable for the load 303. Additionally, the power receiver controller 301 can include various power receiver controller functions required to perform power transfer, particularly functions required to perform power transfer according to the Qi standard.

[0079] To support communication from the power receiver 105 to the power transmitter 101, the power receiver 105 includes a second communication coil 309 and a second communication coil 309. The second communication coil 309 is configured to couple with the first communication coil 207 such that a communication carrier signal induces a current (at least an electromotive force) in the second communication coil 309.

[0080] The second communicator 307 is coupled to the second communication coil 309 and is configured to determine the amplitude variations of the induced signal and demodulate the amplitude modulation of the communication carrier signal. In this manner, the second communicator 307 is configured to decode data transmitted from the power transmitter by amplitude modulation of the communication carrier signal. It will be appreciated that in other embodiments, the second communicator 307 may be configured to decode data modulated onto the communication carrier signal using other forms of modulation, such as frequency modulation or phase modulation.

[0081] The second communicator 307 is further configured to load modulate the communication carrier signal to transmit data from the power receiver to the power transmitter. Specifically, the second communicator 307 may have a load (such as a capacitor) that can be switchably coupled or not coupled to the second communication coil 309 depending on the data to be transmitted. These load modulations are detected by the first communicator 205 of the power transmitter.

[0082] In a specific example, the second communication coil 309 and the second communication device 307 can provide an NFC-compatible communication operation. Specifically, the second communication coil 309 can provide functionality compatible with NFC tags and be configured to decode data ASK-modulated onto a communication carrier signal in accordance with the NFC standard.

[0083] The second communicator 307 is then configured to transmit data to the power transmitter 101 by varying the load on the receiver coil 107 according to the data to be transmitted to the power transmitter 101. The load variation is then detected and demodulated by the power transmitter 101, as known to those skilled in the art.

[0084] In an embodiment, the second communicator 307 is further configured to demodulate the amplitude, frequency and / or phase modulation of the communication carrier signal to retrieve the data transmitted from the power transmitter.

[0085] The system employs recurring time frames during the power transfer phase, each time frame including at least one power transfer time interval and at least one communication time interval. An example of such a recurring time frame is shown in FIG. 4, where the power transfer time interval is designated PT and the communication time interval is designated C. In this example, each time frame FRM consists of only one communication time interval and one power transfer time interval. However, it will be understood that in other embodiments, other time intervals may also be included in the time frame, or multiple communication time intervals and / or power transfer time intervals may be included in each time frame.

[0086] The power transfer driver 201 is controlled by the power transmitter controller 205 to generate the drive signal only during the power transfer time intervals and not during the communication time intervals. Thus, the driver generates the drive signal, and therefore the power transfer signal, during the power transfer time intervals, while the drive signal, and therefore the power transfer signal, is turned off during the communication time intervals.

[0087] Thus, in the power transmission phase, the power transmitter is configured to perform power transmission during power transmission time intervals of the time frame of the power transmission phase. In particular, during these time intervals, the power transmitter and the power receiver can operate a power control loop (which can be based on communication within communication time intervals corresponding to the recurrence time intervals). Thus, the level of transmitted power can be dynamically changed.

[0088] However, during the communication time interval of the power transfer phase time frame, the power drive signal is switched off so that no power transfer signal is generated during the communication time interval.

[0089] The communication between the power transmitter and the power receiver is performed during the communication time interval during the power transmission phase, and typically only during the communication time interval. The communication via the first communication coil 207 and the second communication coil 309 is performed only during the communication time interval, specifically, the modulation of the communication carrier signal is performed only during the communication time interval.

[0090] Thus, in this system, the first transceiver 205 is configured to transmit data, and therefore modulate (e.g., amplitude) the communications carrier signal, only during the communication time interval, and similarly typically only attempt to demodulate the data during the communication time interval.

[0091] Similarly, the second communicator 307 is configured to communicate only during the communication time interval when in the power transfer phase. Thus, in this system, the second communicator 307 is configured to transmit data, and thus load modulate the communication carrier signal, only during the communication time interval. Similarly, it typically only attempts to demodulate data during the communication time interval.

[0092] Thus, during the power transfer phase, the first communicator 205 and the second communicator 307 are configured to communicate only during the communication time interval. Such an approach can provide highly advantageous performance, and has been found to significantly improve communication performance. In particular, this approach reduces interference with communication operations from the power transfer signals and provides more reliable and robust communication with reduced bit errors.

[0093] An example of how communication during the communication time intervals of a recurring time frame is performed is shown in Figure 5. In this figure, a power transmission signal 501 is generated during a power transmission time interval PT, and a modulated communication carrier signal 503 is generated during a communication time interval C. In Figure 5, each operation is performed in a dedicated time interval, achieving time division between power transmission and communication.

[0094] However, in Figures 1-4, a more flexible and overlapping approach is applied. In this approach, the power transmitter is configured to generate a communication carrier signal so that it exists during the power transmission time interval, resulting in coexistence while the power transmission signal is generated during the power transmission time interval. However, the communication carrier signal is not generated so that it exists continuously; rather, one or more timing gaps are inserted into the time frame during which the communication drive signal and the communication carrier signal are not generated. Therefore, a relatively short gap is typically inserted in the generation of the communication carrier signal. Furthermore, in this approach, the modulation of the communication carrier signal is controlled in a different manner from the generation of the communication carrier signal; specifically, the modulation is controlled so that it occurs only during the communication time interval. Therefore, the communication drive signal and the communication carrier signal generated during the power transmission time interval are unmodulated.

[0095] Figure 6 shows an example of an approach that may be used in the systems of Figures 1 to 4. In this example, a power transmission signal 601 is generated similar to that of Figure 5, but the communications carrier signal 603 is generated throughout the repeated time frames, except for a short timing gap within each time frame where the communications carrier signal 603 is switched off.

[0096] This approach can be used, among other things, to provide a second, low-level power transmission path from a power transmitter to a power receiver. In particular, the power receiver includes a power extractor 311 configured to extract power from a communication carrier signal, if present. In a specific example, the power extractor 311 can optionally extract power from an NFC carrier signal.

[0097] Therefore, power can be provided from a power transmitter to a power receiver via communication carrier signal / NFC carrier power harvesting, which can power low-power level, e.g., low-voltage electronics such as NFC hardware and user interfaces.

[0098] The power extractor 311 is relatively simple and an example of the power extraction circuit / path is shown in FIG.

[0099] FIG. 7 is a circuit diagram illustrating example elements of the power path of the power extractor 311. In this example, the second communication coil 309 is designated LRX, and when a communication carrier signal is applied to it, a corresponding AC voltage / current is induced in the coil. The second communication coil 309 is coupled to a series capacitor CRX, which together form an input resonant circuit further coupled to a rectifier bridge B1 with a smoothing capacitor C1 coupled to the bridge's output. Thus, a DC voltage is generated across capacitor C1. The magnitude of the ripple in the DC voltage is determined by the size of the smoothing capacitor and the load RL supplied by the power extractor 311. Using the input resonant circuit formed by LRX and CRX allows for more efficient power transfer coupling. The inclusion of CRX causes the circuit to resonate at the communication carrier frequency, so power harvesting occurs primarily at the communication frequency.

[0100] Bridge B1 and smoothing capacitor C1 are coupled to load RL via switch S1, which can be used to turn power extraction / harvesting on and off. It will be appreciated that in many embodiments, power extractor 311 can be directly and permanently coupled to load RL without a switch.

[0101] 7 further shows a load modulation capacitor C2 that can be connected or disconnected in parallel with the second communication coil 309 based on the switching of switch S2. The second communication device 307 can control switch S2 during the communication time interval to provide the desired load modulation.

[0102] Therefore, the power extractor 311 can be implemented with low complexity and low cost circuitry.

[0103] Power extraction is supported by the long duration of the communication carrier signal, which is generated even during the power transmission time interval. In fact, in many embodiments, the timing gaps during which the communication carrier signal is not generated are so short that they are virtually negligible, allowing power extraction to occur nearly constantly. This significantly increases the extracted power. For example, in an NFC implementation, the extracted power can typically reach approximately 200 mW, whereas using an approach like that of Figure 5, which typically has a communication time interval of approximately 1.5 ms per 10 ms time frame, only 30 mW can be extracted. Furthermore, because the smoothing capacitor only needs to support power during the short timing gaps rather than the majority of the time frame, a more stable output voltage with significantly reduced ripple can be achieved. This significantly reduces cost and reliability, as capacitors are generally not only relatively expensive but also less reliable and more prone to errors than many electronic components.

[0104] The ability to extract more power from a communications carrier signal can be very important in many scenarios and can enable significant design flexibility. Increasing power levels can significantly reduce complexity and price in many practical applications. In fact, if more power is required than can be extracted from the communications carrier signal with a given approach, an additional power supply must be implemented to extract power from the high-voltage power transmission system, i.e., from the power transmission signal. This can be, for example, a capacitive power supply requiring high-voltage capacitors or certain types of step-down converters suited to high-voltage inputs. This typically requires components that are much more expensive and bulky than those required for approaches such as the one described for power extractor 311.

[0105] This approach can also improve load modulation by reducing ripple. In the example of Figure 7, the expansion of the communications carrier signal reduces the ripple in the voltage across C1. As a result, the load modulation introduced by C2 is less variable and more consistent, improving load modulation communications. In particular, the fluctuations caused by C2 are more easily detected by the power transmitter because other fluctuations are reduced.

[0106] This approach therefore allows for significant reductions in complexity and cost in many practical applications. For example, a power-receiving device that includes a heating element as a load can be powered directly by a power transmission signal that directly induces current in the heating element. Indeed, in such instances, the described approach often allows control and support circuitry and user interfaces to be fully powered by a communications carrier signal, specifically an NFC carrier. This approach therefore makes it possible, in some cases, to design a power-receiving device that does not include electronic circuits powered by the power transmission signal. Thus, complex high-voltage power extraction circuitry can be completely avoided, which is typically not possible when supplying only 30 mW, for example.

[0107] However, rather than generating a continuous power transmission signal throughout the entire time frame, the system applies one or more timing gaps in the time frame during which no communication drive signal and communication carrier signal are generated (hereafter referred to simply as timing gaps for brevity). In the example of Figure 6, short timing gaps 605 are introduced at the end of each power transmission time interval and just before the start of each communication time interval.

[0108] These timing gaps are used to provide timing information from the power transmitter to the power receiver. Specifically, timing gaps can be introduced to start and / or stop at specific and / or predetermined instants within each time frame.

[0109] 3 includes a synchronizer 313 that synchronizes the operation of the power receiver to the timing of the timing gap. The synchronizer 313 can specifically adapt the time of the local time base according to the timing of the timing gap, and the operation of the power receiver can be synchronized according to the local time base.

[0110] Operations that can be synchronized to the timing of the timing gaps can include any suitable time-based operations of the power receiver. In particular, the synchronizer 313 can synchronize the timing of locally applied recurring time frames, i.e., synchronize the application and operation of functions timed to the recurring time frames. The synchronizer 313 can, in particular, synchronize the operation of communication time intervals and power transmission time intervals to the timing gaps. As a specific example, modulation and / or demodulation of a communication carrier signal by the second transceiver 307 can be synchronized to / based on the timing of the timing gaps.

[0111] Thus, the timing gap in the communication carrier signal allows the operation of the power transmitter and power receiver to be closely aligned and synchronized, and in particular, the operation of the power receiver to be aligned and synchronized to the recurring time frame adopted by the power transmission signal generated by the power transmission driver.

[0112] Typically, all repeating time frames are identical and have the same time intervals, and these time intervals have the same duration and order within each time frame.

[0113] In many embodiments, the recurring time frame has a duration of 5 to 25 milliseconds, and in many embodiments is 10 milliseconds or 20 milliseconds (for a 50 Hz mains powered power transmitter), or 8.3 milliseconds or 16.7 milliseconds (for a 60 Hz mains powered power transmitter).

[0114] The duration of the power transmission time interval is typically 60% or more, or 80% or more, of the recurrence time frame. In many embodiments, the duration of the power transmission time interval can be in the range of 3 to 20 msec, specifically in the range of 5 to 9.5 msec. In many embodiments, the duration of the power transmission time interval can be in the range of 7 to 9 msec, specifically approximately 8.5 msec.

[0115] The duration of the communication time interval is typically significantly shorter than the power transmission time interval, typically no more than 20% or 30% of the duration of the power transmission time interval. The communication time interval is typically in the range of 1 to 2 milliseconds.

[0116] The duration of the timing gaps will depend on the particular needs and requirements of each individual embodiment. However, the communications carrier signal is generated to extend substantially over the power transmission time interval, and specifically, the total duration of the set of timing gaps is 50% or less of the duration of the power transmission time interval. Thus, the communications carrier signal is generated for at least 50% of the power transmission time interval. In many embodiments, the total duration of the timing gaps is significantly shorter; indeed, in many embodiments, the total duration of the set of timing gaps is 20% or less, 10% or less, 5% or less, 2% or less, or even 1% or less of the duration of the power transmission time interval and / or the recurring time frame.

[0117] As such, the duration of the timing gaps can be kept relatively short, thereby increasing the extracted power level. At the same time, the timing gaps can be kept long enough to be detected by synchronizer 313 to enable accurate timing determination. In many embodiments, each timing gap is no less than 0.1%, 0.5%, 1%, 2%, or 5% of the duration of the timing frame. In many embodiments, the duration of the timing gaps can be in the range of 0.1 msec to 5 msec, specifically in the range of 0.2 msec to 1 msec.

[0118] The specific generation of the communication drive signal and communication carrier signal is suitably implemented so that the signals can serve multiple functions in addition to the primary purpose of communication for which they are provided. In particular, this approach has the advantage of being able to generate a communication carrier signal that not only provides a communication means / carrier, but also enables an efficient low-level power transmission path and provides timing / synchronization information from the power transmitter to the power receiver.

[0119] Thus, highly efficient operation is achieved which not only provides significant performance advantages but also reduces the complexity and cost of the circuitry required in the power receiver.

[0120] This approach is particularly advantageous in embodiments where the communication carrier signal is an NFC carrier. In such embodiments, the power transmitter can implement NFC reader functionality. In such an approach, the NFC is the master, controlling the communication, and the power receiver listens and responds as needed. Therefore, the timing of the communication is transparent to the power receiver. However, the described approach can advantageously and efficiently provide a timing synchronization approach.

[0121] Another advantage of continuously powering functions with power extracted from the NFC carrier is that such power is very stable, independent of the power delivered to the mains load by inductive power transfer. For example, Ki power receivers cover a wide range of power levels. A blender, for example, may require power from 25W to 1.5kW depending on how it is used. Therefore, the mains power supply must be able to accommodate this large input range and always provide sufficient power to the low-voltage circuits. This is especially important at very low power levels, when phase-cut / discontinuous mode is used and power transfer only occurs for part of the mains power cycle.

[0122] In many embodiments, the power driver 201 may be powered by a time-varying power supply signal. In particular, the supply voltage to the output stage may be generated from an AC voltage, and in particular from the AC mains voltage. In some embodiments, the AC voltage may be used directly as the supply voltage to the output circuit (e.g., inverter) of the power driver 201. In many embodiments, the supply voltage is also generated as a rectified mains voltage. Thus, in many embodiments, the (absolute) supply voltage varies as a (possibly rectified) sine wave with a predetermined period. As a result, the generated power transfer drive signal has a (sinusoidal) time-varying amplitude, as also shown in Figures 5 and 6. The amplitude has a minimum value (usually zero value) corresponding to the zero crossings of the input supply voltage, in particular the mains. Therefore, the power transfer drive signal / power transfer signal is generated with an amplitude period that is half the period of the AC mains signal.

[0123] In such an embodiment, the recurring time frames, and thus the power transmission time intervals and the communication time intervals, can be synchronized to the timing of the varying power supply signal and thus the amplitude variations of the power transmission drive signal. In particular, the communication time intervals can be configured to be at (or include) amplitude minima (corresponding to zero crossings of the mains signal).

[0124] Similarly, the communications driver 209 is configured to generate the communications drive signal, and thus the communications carrier signal, such that the timing gap is also synchronized to the varying power supply signal.

[0125] Thus, in many embodiments, the recurring time frames, power transmission time intervals, communication time intervals and timing gaps are synchronized (particularly in the power transmitter) to a time-varying power supply signal, particularly the mains power supply.

[0126] The timing gap may be placed at different positions in the time frame in different embodiments.

[0127] In many embodiments, a timing gap can be included to indicate the transition from the power transfer time interval to the communication time interval. For example, in the example of FIG. 6, the timing gap is located at the end of the power transfer time interval and, therefore, at the beginning of the communication time interval. Such a timing gap can facilitate synchronization of the recurring time frames at the receiver and, in particular, allow for low-complexity adaptation of the timing of operations related to the communication time interval and the power transfer time interval. In particular, this can improve and / or simplify adaptation of the timing of communication operations. The synchronizer 313 can, for example, simply detect the timing gap and switch to communication time interval operation upon detecting the end of the timing gap. Specifically, modulation / demodulation can be performed immediately after the end of the timing gap is detected.

[0128] In some embodiments, the power transmitter can alternatively or additionally add a timing gap at the beginning of a power transmission time interval. For example, just before the power transmission signal is turned on by the power transmission driver 201 that generates the power transmission drive signal, the communication driver 209 can be controlled to insert a gap in the generated communication carrier signal so that it ends when the power transmission signal is turned on. Such a gap can be used, for example, by the synchronizer 313 of the power receiver to switch on a load, end modulation of the communication carrier signal, stop demodulation of the communication carrier signal, etc.

[0129] Another example of an operation or process that can be synchronized by the timing of such timing gaps is the measurement of true effective power by measuring the power during a complete repeating time frame, which may correspond to a mains period, and calculating the effective power from the measured values. To perform such a measurement, it is important that the entire mains period is measured, and therefore the measurement needs to start simultaneously with the start of the mains period and end exactly at its end. This period is, in some embodiments, represented by the interval between two timing gaps.

[0130] In some embodiments, for example, timing gaps can alternatively or additionally be placed at other times within the repeating time frame, specifically within the power transfer time interval. For example, a timing gap can be inserted at the maximum amplitude level of the power transfer signal, thereby enabling accurate measurement of this level at the power receiver simply by timing a measurement to this timing gap. Such measurements can be useful, for example, as an indicator of power transfer (e.g., to a heating element or motor).

[0131] In many embodiments, one or more of the timing gaps are included in the power transfer time interval, and indeed in many embodiments, timing gaps are introduced only during the power transfer time interval. In many embodiments, no timing gaps are included in the communication time interval.

[0132] Such an approach often improves performance by mitigating the effects of timing gaps (e.g., avoiding communications interruptions due to the absence of a communication carrier signal available for modulation), and in many scenarios allows for a less complex and easier synchronizer 313 at the power receiver side (e.g., the function can be triggered simply by detecting the start or end of a timing gap, as in the example provided above).

[0133] However, it will be appreciated that in some embodiments, one, more, or all of the timing gaps may be outside the power transmission time interval and may actually be within the communication time interval. For example, the timing gaps may be located at the beginning of the communication time interval rather than at the end of the power transmission time interval. For example, the start of the timing gap occurs simultaneously with the power transmission signal being turned off, and the end of the timing gap occurs, for example, after a certain duration of the timing gap. In such a case, the synchronizer 313 may be controlled to start modulation / demodulation at the end of the timing gap.

[0134] Each repeating time frame may include only a single timing gap, which may, for example, allow for low complexity operation and minimize interruptions to the communications carrier signal.

[0135] However, in this approach, the timing gaps may include a set of patterns of timing gaps, which may be specifically predetermined patterns, given / characterized by the durations of the timing gaps and the delays / time offsets between the timing gaps.

[0136] It will be appreciated that in many embodiments the duration of each timing gap may be the same, but in some embodiments the timing gaps may have different durations. Similarly, the time offset between adjacent timing gaps may typically be the same, but in some embodiments may be different.

[0137] In some embodiments, the predetermined pattern may be a set of timing gaps that have the same duration and the same time offset / delay / duration between successive timing gaps in the same repeating time frame. Figure 7 shows an example of such an approach, where a pattern of four short, equidistant timing gaps of the same duration is used.

[0138] The use of such patterns can often result in improved operation. Typically, it improves detection of timing gaps, which allows for more accurate synchronization. Indeed, using a pattern rather than a single timing gap may have the advantage of improved detectability. In many embodiments, there are multiple mechanisms that can cause gaps in the NFC carrier, such as communication errors, transitions between connected and power modes, and foreign object detection (FOD) measurements. This can make it difficult in some embodiments for the power receiver to properly distinguish between timing gaps and other gaps caused by other factors, such as those mentioned above. A pattern that is highly unlikely or impossible to arise from other events can allow for more accurate and reliable detection and synchronization.

[0139] In some embodiments, the pattern can be a pattern selected from a number of predetermined patterns, which allows, for example, identification of the power transmitter and allows coexistence between different power transmitters.

[0140] For example, a power transmitter configuration may include multiple transmit coils located relatively close to one another. For example, a countertop may have multiple power transmission locations available for use by a power receiving device. However, as a result, multiple communication carrier signals may be generated in close proximity to one another. In some embodiments, different patterns of timing gaps may be used for different transmit coils. This reduces interference, improves synchronization, and increases interoperability between different transmit coils / power transmitters located in close proximity to one another.

[0141] In many embodiments, the power transmitter and power receiver can be configured to adapt characteristics of one or more timing gaps based on a communication exchange between the power transmitter and the power receiver. In particular, a configuration message can be transmitted from the power receiver with a request or indication of the characteristics of the timing gaps. The configuration message can, for example, include a direct or indirect request for the characteristics of at least one of the timing gaps. Alternatively or additionally, the configuration message can provide information for the configuration of the power receiver. The configuration message can, for example, be part of a negotiation approach performed during initialization of power transmission (e.g., during the connection phase of the power receiver and the wireless power transmission system). The power transmitter can then proceed to adapt the characteristics of the timing gaps in response to the configuration message. For example, the power receiver can request a specific timing gap pattern or timing gap duration, and the power transmitter can proceed to set the values ​​accordingly.

[0142] In some embodiments, the configuration message may indicate whether the power receiver can support the described operation (e.g., a power receiver that can support an operation is configured to send a message indicating that it has such capability). This indication may be directly related to the operation, or it may be more general (e.g., indicating the version of the specification that the power receiver supports). In such a case, the power transmitter is configured to use the described operation, in particular the timing gap, only if the power receiver indicates that it can support that operation.

[0143] In the case of an NFC implementation, the configuration message can specifically be an NDEF (NFC Data Exchange Format) message.

[0144] It will be understood that, for clarity, the above description has described embodiments of the invention with reference to different functional circuits, units, and processors. However, it will be apparent that any suitable distribution of functionality between different functional circuits, units, or processors may be used without departing from the invention. For example, functionality shown to be performed by separate processors or controllers may be performed by the same processor or controller. References to specific functional units or circuits should therefore be seen only as references to suitable means for providing the described functionality, rather than to indicative of a strict logical or physical structure or organization.

[0145] The invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented at least partly as computer software running on one or more data processors and / or digital signal processors. The elements and components of embodiments of the invention may be physically, functionally, and logically implemented in any suitable way. Indeed, functionality may be implemented in a single unit, in multiple units, or as part of other functional units. Thus, the invention may be implemented in a single unit, or may be physically and functionally distributed between different units, circuits, and processors.

[0146] Although the present invention has been described in connection with several embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the appended claims. Furthermore, while certain features may appear to be described in connection with particular embodiments, those skilled in the art will recognize that various features of the described embodiments may be combined in accordance with the present invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

[0147] It will be understood that the reference to the preferred value does not imply any limitation beyond it being the value determined in the foreign object detection initialization mode, i.e., it is preferably determined in the adaptation process. Reference to the preferred value can be replaced with a reference to the first value, for example.

[0148] Furthermore, although individually listed, a plurality of means, elements, circuits, or method steps may be implemented by, for example, a single circuit, unit, or processor. Furthermore, although individual features may be included in different claims, these may be advantageously combined in some cases, and their inclusion in different claims does not imply that a combination of features is not feasible and / or advantageous. Moreover, the inclusion of a feature in one category of claims does not imply limitation to this category, but rather indicates that the feature is equally applicable to other claim categories, where appropriate. Furthermore, the order of features in the claims does not imply a particular order in which the features must operate, and in particular the order of individual steps in method claims does not imply that the steps must be performed in this order. Rather, steps may be performed in any suitable order. Furthermore, a reference to the singular does not exclude a plurality; thus, references to "a," "an," "first," "second," etc. do not exclude a plurality. Reference signs in the claims are provided merely as a clarifying example and should not be construed as limiting the scope of the claims in any way.

[0149] In general, examples of a power transmitter and its operating method, a power receiver and its operating method, and a wireless power transmitter are illustrated by the following embodiments. Embodiments: Embodiment 1. A power transmitter (101) for wirelessly supplying power to a power receiver (105) via an inductive power transmission signal, the power transmitter (101) comprising: a power transmission coil (103) configured to generate a power transmission signal; a power transmission driver (201) configured to generate a power transmission drive signal for a power transmission coil (103), the power transmission driver (201) configured to generate the power transmission drive signal to employ a recurring time frame including at least a power transmission time interval and a communication time interval during a power transmission phase, the power transmission driver (201) configured to generate the power transmission drive signal during the power transmission time interval and not generate the power transmission drive signal during the communication time interval; a communication coil (207) configured to generate a communication carrier signal; a communication driver (209) configured to generate a communication drive signal for causing the communication coil to generate a communication carrier signal; a communication unit (205) configured to communicate with the power receiver (105) using modulation of a communication carrier signal during a communication time interval; The power transmitter, wherein the communications driver (205) is configured to generate the communications drive signal to be present during the communications time interval and the power transmission time interval except during a set of timing gaps during which the communications drive signal is not generated, the total duration of the set of timing gaps being less than or equal to 50% of the duration of the power transmission time interval. Embodiment 2. A power transmitter (101) as described in any of the previous embodiments, wherein the communication driver (205) is configured to generate the communication drive signal such that at least a first timing gap of a set of timing gaps has a fixed time offset relative to the timing of the power transmission time interval. Embodiment 3. The power transmitter (101) of any of the previous embodiments, wherein a set of timing gaps is included in the power transmission time interval. Embodiment 4. The power transmitter (101) of any of the previous embodiments, wherein the set of timing gaps consists of a predetermined pattern of a plurality of timing gaps. Embodiment 5. A power transmitter (101) as described in embodiment 4, wherein the predetermined pattern is a pattern of multiple timing gaps having the same duration and the same time difference between successive timing gaps of the same repeating time frame. Embodiment 6. The power transmitter (101) of embodiment 4 or 5, wherein the predetermined pattern is selected from a plurality of predetermined patterns. Embodiment 7. The power transmitter of any of the previous embodiments, wherein the power transmission driver (201) is configured to be powered by a time-varying power supply signal, and the communication driver (205) is configured to synchronize the timing of the set of timing gaps to the varying power supply signal. Embodiment 8. A power transmitter (101) as described in any of the previous embodiments, wherein the communication driver (205) is configured to synchronize the end of a timing gap of a set of timing gaps with the end of the power transmission time interval. Embodiment 9. A power transmitter (101) as described in any of the previous embodiments, wherein the power transmitter (101) is configured to exchange configuration messages with the power receiver (105), the configuration messages including an indication of characteristics of at least one timing gap among the plurality of timing gaps. Embodiment 10. The power transmitter (101) of any preceding embodiment, wherein the combined duration of the timing gaps is less than or equal to 5% of the duration of the power transmission time interval. Embodiment 11. A power receiver (105) for wirelessly receiving power from a power transmitter (101) via an electromagnetic power transmission signal, the power transmission signal employing a recurring time frame including at least a power transmission time interval and a communication time interval, the power transmission signal being present during the power transmission time interval and not present during the communication time interval, the power receiver (105) comprising: an inductive power extraction element (107) configured to extract power from the power transmission signal during a power transfer time interval of the power transfer phase; a communications coil (309) for receiving a received communications carrier signal, the communications carrier signal being present during the communications time interval and the power transfer time interval except during a set of timing gaps in which the communications carrier signal is not present, the total duration of the timing gaps being 50% or less of the duration of the power transfer time interval; a communication unit (307) configured to communicate with the power transmitter using modulation of a communication carrier signal during a communication time interval; a synchronizer (313) configured to synchronize operation of the power receiver to the timing of a set of timing gaps. Embodiment 12. A power receiver further comprising a power extractor (311) coupled to the communication coil (309) and configured to extract a power signal from the communication coil (309) and power a circuit of the power receiver with the power signal. Embodiment 13. A wireless power transmission system comprising the power transmitter according to any one of embodiments 1 to 10 and the power receiver according to any one of embodiments 11 and 12. Embodiment 14. A method of operating a power transmitter (101) that wirelessly supplies power to a power receiver (105) via an inductive power transmission signal, comprising: A power transmission coil (103) generates a power transmission signal; generating a power transmission drive signal for the power transmission coil (103), wherein the drive signal during a power transmission phase is generated to employ a recurring time frame including at least a power transmission time interval and a communication time interval, and the power transmission drive signal is generated to be present during the power transmission time interval but not during the communication time interval; A communication coil (207) generates a communication carrier signal; generating a communication drive signal for causing a communication coil to generate a communication carrier signal; communicating with a power receiver (105) using modulation of a communications carrier signal during a communications time interval; The method, wherein the communication drive signal is generated to be present during the communication time interval and the power transmission time interval, except for a set of timing gaps during which the communication drive signal is not generated, and the total duration of the set of timing gaps is less than or equal to 50% of the duration of the power transmission time interval. Embodiment 15. A method of operating a power receiver (105) for wirelessly receiving power from a power transmitter (101) via an electromagnetic power transmission signal, the power transmission signal employing a recurring time frame including at least a power transmission time interval and a communication time interval, the power transmission signal being present during the power transmission time interval and not present during the communication time interval, the method comprising: extracting power from the power transmission signal during a power transmission time interval of the power transmission phase; receiving a communications carrier signal with a communications coil (309), the communications carrier signal being present during the communications time interval and the power transmission time interval except during a set of timing gaps in which the communications carrier signal is not present, the total duration of the timing gaps being less than or equal to 50% of the duration of the power transmission time interval; communicating with a power transmitter using modulation of a communications carrier signal during a communication time interval; and synchronizing operation of the power receiver to the timing of the set of timing gaps.

Claims

1. 1. A power transmitter for wirelessly supplying power to a power receiver via an inductive power transmission signal, comprising: a power transfer coil configured to generate the power transfer signal; a power transfer driver configured to generate a power transfer drive signal for the power transfer coil, the power transfer driver configured to generate the power transfer drive signal to employ a recurring time frame during a power transfer phase, the time frame including at least a power transfer time interval and a communication time interval, the power transfer driver configured to generate the power transfer drive signal during the power transfer time interval and not generate the power transfer drive signal during the communication time interval; a communications coil configured to generate a communications carrier signal; a communication driver configured to generate a communication drive signal for causing the communication coil to generate the communication carrier signal; a communication unit configured to communicate with the power receiver using modulation of the communication carrier signal during the communication time interval; a power transmitter, wherein the communication driver is configured to generate the communication drive signal to be present during the communication time interval and the power transmission time interval except during a set of timing gaps during which no communication drive signal is generated, the set of timing gaps having a total duration that is less than or equal to 50% of the duration of the power transmission time interval, and the set of timing gaps consisting of a predetermined pattern of a plurality of timing gaps.

2. 2. The power transmitter of claim 1, wherein the communication driver is configured to generate the communication drive signal such that at least a first timing gap of the set of timing gaps has a fixed time offset relative to the timing of the power transmission time interval.

3. 3. The power transmitter of claim 1, wherein the set of timing gaps is included in the power transmission time interval.

4. 2. The power transmitter of claim 1, wherein the predetermined pattern is a pattern of timing gaps having the same duration and the same time difference between successive timing gaps of the same recurring time frame.

5. 5. The power transmitter of claim 1, wherein the predetermined pattern is selected from a plurality of predetermined patterns.

6. 6. A power transmitter according to claim 1, wherein the power transmission driver is configured to be powered by a time-varying power supply signal, and the communication driver is configured to synchronize the timing of the set of timing gaps to the time-varying power supply signal.

7. 8. The power transmitter of claim 1, wherein the communication driver is configured to synchronize an end of a timing gap in the set of timing gaps with an end of the power transmission time interval.

8. 8. The power transmitter of claim 1, wherein the power transmitter is configured to exchange configuration messages with the power receiver, the configuration messages including an indication of a characteristic of at least one timing gap of the plurality of timing gaps.

9. 9. A power receiver according to claim 1, wherein the total duration of the timing gaps is less than or equal to 5% of the duration of the power transfer time interval.

10. 1. A power receiver for wirelessly receiving power from a power transmitter via an electromagnetic power transmission signal, the power transmission signal employing a recurring time frame including at least a power transmission time interval and a communication time interval, the power transmission signal being present during the power transmission time interval and not present during the communication time interval, the power receiver comprising: an inductive power extraction element configured to extract power from the power transmission signal during the power transfer time interval of a power transfer phase; a communications coil for receiving a received communications carrier signal, the communications carrier signal being present during the communications time interval and the power transfer time interval except during a set of timing gaps in which no communications carrier signal is present, the total duration of the timing gaps being 50% or less of the duration of the power transfer time interval; a communication unit configured to communicate with the power transmitter using modulation of the communication carrier signal during the communication time interval; a synchronizer for synchronizing operation of the power receiver to the timing of the set of timing gaps; The set of timing gaps comprises a predetermined pattern of timing gaps.

11. 11. The power receiver of claim 10, further comprising a power extractor coupled to the communication coil and configured to extract a power signal from the communication coil and power circuitry of the power receiver with the power signal.

12. A wireless power transmission system comprising: a power transmitter according to any one of claims 1 to 9; and a power receiver according to claim 10 or 11.

13. 1. A method of operating a power transmitter that wirelessly supplies power to a power receiver via an inductive power transmission signal, comprising: a power transfer coil generating a power transfer signal; generating a power transfer drive signal for the power transfer coil, the power transfer drive signal during a power transfer phase being generated to employ a recurring time frame including at least a power transfer time interval and a communication time interval, the power transfer drive signal being generated to be present during the power transfer time interval but not during the communication time interval; a communication coil generating a communication carrier signal; generating a communication drive signal for causing the communication coil to generate the communication carrier signal; communicating with the power receiver using modulation of the communications carrier signal during the communication time interval; the communication drive signal is generated to be present during the communication time interval and the power transmission time interval except during a set of timing gaps during which the communication drive signal is not generated, the total duration of the set of timing gaps is less than or equal to 50% of the duration of the power transmission time interval, and the set of timing gaps consists of a predetermined pattern of a plurality of timing gaps.

14. 1. A method of operating a power receiver for wirelessly receiving power from a power transmitter via an electromagnetic power transmission signal, the power transmission signal employing a recurring time frame including at least a power transmission time interval and a communication time interval, the power transmission signal being present during the power transmission time interval and not present during the communication time interval, the method comprising: extracting power from the power transmission signal during the power transmission time interval of a power transmission phase; receiving a communications carrier signal received by a communications coil, the communications carrier signal being present during the communications time interval and the power transfer time interval except during a set of timing gaps in which no communications carrier signal is present, the total duration of the timing gaps being less than or equal to 50% of the duration of the power transfer time interval; communicating with a power transmitter using modulation of a communications carrier signal during the communication time interval; and synchronizing operation of the power receiver to the timing of the set of timing gaps; The method, wherein the set of timing gaps consists of a predetermined pattern of timing gaps.

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