Wireless Power Transmission

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. A communication driver 209 generates a communication drive signal for the communication coil 207 to generate a communication carrier signal. The power transmitter operates in a connected mode in which the communication carrier signal is active 50% or more of the time, and in a low-power standby mode in which the communication carrier signal is active 50% or less of the time. The mode controller 203 can switch the power transmitter from the connected mode to the standby mode when a timer 211 expires. The duration of the timer is set based on a standby timeout indicator sent from the power receiver 105 to the power transmitter 101. This approach can provide a response tailored to a particular power receiver while consuming low power.

Description

[Technical Field]

[0001] The present invention relates to the operation of wireless power transmission from a power transmitter to a power receiver, and particularly, but not exclusively, to transmitting power wirelessly to high power devices such as kitchen appliances. [Background technology]

[0002] Most electronic products today require dedicated electrical contacts to be powered from an external source. However, this tends to be impractical, requiring the user to physically insert a connector or establish physical electrical contact. Power requirements also typically vary widely, and most devices now have their own dedicated power sources, resulting in the typical user owning numerous different power sources, each dedicated to a specific device. While using an internal battery could eliminate the need for a wired connection to a power source during use, this is only a partial solution, as the battery will still need to be recharged (or replaced). Using a battery can significantly increase the weight of the device, as well as its cost and size.

[0003] To significantly improve the user experience, it has been proposed to use wireless power sources in which power is inductively transferred from a transmitting inductor in a power transmitting device to a receiving coil in an individual device.

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

[0005] Such a configuration allows for wireless power transfer to the device without the need for wires or physical electrical connections. In fact, the device can be externally charged or powered simply by being placed next to or on top of the transmitter coil. For example, the power transmission device can be placed on a horizontal surface where the device can be powered simply by being placed on it.

[0006] Moreover, such wireless power transmission configurations may be advantageously designed to allow a power transmitter to be used with a variety of power receivers. In particular, a wireless power transmission approach known as the Qi specification has been defined and is currently being further developed. This approach allows a power transmitter conforming to the Qi specification to be used with a power receiver that also conforms to the Qi specification, without the devices needing to be from the same manufacturer or proprietary to each other. The Qi standard further includes several features that allow it to adapt its operation to a particular power receiver (e.g., depending on a particular power consumption).

[0007] The Wireless Power Consortium has been developing the Ki specification (also known as the Cordless Kitchen standard) based on the Qi standard, which aims to provide safe, reliable and efficient wireless power transfer to kitchen appliances. Ki supports very high power levels up to 2.5KW.

[0008] 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, it may be difficult to detect such load modulation if the power transmission load of the power transmission signal is also fluctuating at the same time. Similarly, communication from a power transmitter to a power receiver may be achieved by modulating the power transmission signal (e.g., amplitude modulation or frequency modulation), but interference with such modulation may occur due to fluctuations in the parameters of the power transmission signal, for example, due to load fluctuations.

[0009] 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.

[0010] 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, a user interface, etc. However, such an approach requires additional functionality and may not be optimal in all scenarios.

[0011] It has been proposed that power can be extracted from the NFC carrier to power low-power electronic circuits. However, while such approaches may be useful in many scenarios, they tend to be suboptimal in some respects. For example, they tend to provide suboptimal initialization and continuous power supply, which may not be ideal in all cases for the circuits they power.

[0012] A particular problem for some power-receiving devices is that when placed at a particular power transmitter's power transmission location, power transmission may not be immediately required. This can lead to scenarios in which the power transmitter and power receiver interact (e.g., communicate with each other) but do not necessarily initiate power transmission in the short term. For example, systems such as Ki enter a connection phase in which communication occurs while waiting for a change, such as a request to initiate the power transmission system. However, the problem with this state is that it can be power-hungry and can persist for long periods (e.g., hours or days), resulting in high energy consumption, even if the power consumption is relatively low. For example, a kettle may be placed at a power transmitter for an extended period, but water is only boiled at long intervals.

[0013] While switching to a lower power state may be attractive, this tends to be suboptimal as it typically slows down operation and user interaction. Furthermore, the optimal state for use may differ for different scenarios and devices, making the trade-off between power efficiency and user convenience very difficult to achieve. Summary of the Invention [Problem to be solved by the invention]

[0014] Therefore, improved operation for wireless power transfer systems would be advantageous, and in particular approaches that allow for increased flexibility, reduced cost, reduced complexity, improved communication, additional functionality, improved secondary power supply, reduced power consumption (especially outside of power transfer), improved operation, improved trade-off between power consumption and user responsiveness and experience, improved accommodation to different devices, and improved compatibility and / or performance for systems with non-uniform power receivers would be advantageous.

[0015] Accordingly, the Invention seeks to preferably mitigate, reduce or eliminate one or more of the above mentioned disadvantages singly or in any combination. [Means for solving the problem]

[0016] 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 a power transmission drive signal for the power transmission coil, the power transmission driver configured to generate the power transmission drive signal during a power transmission phase; a communications coil configured to generate a communications carrier signal; a communications driver configured to generate the 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, the communications unit configured to receive a configuration message from the power receiver. the configuration message includes a standby timeout indicator; and a mode controller configured to control the power transmitter to switch between different modes, including a power transmission mode in which a power transmission signal is generated by a power transmission driver generating a drive signal, a connected mode in which no power transmission signal is generated and a communication carrier is generated 50% or more of the time, and a standby mode in which no power transmission signal is generated and a communication carrier is generated 10% or less of the time, wherein the mode controller is configured to, in the connected mode, start a timer with an initial timing duration determined depending on the standby timeout indicator, and transition the power transmitter from the connected mode to the standby mode in response to expiration of the timer.

[0017] The present invention allows for improved performance and / or operation and / or implementation in many embodiments, which allows for improved overall power transfer operation in many systems and embodiments.

[0018] This approach, in many embodiments, significantly reduces power consumption while still allowing for adequate response time. This allows the tradeoff between power consumption and response time to be tailored to the specific characteristics, requirements, and / or preferences of individual power receivers. Improved, more user-friendly low-power standby operation can be achieved. In many embodiments, reduced power consumption can be achieved with reduced impact on the user experience.

[0019] This approach is particularly suitable in many scenarios for power transmission systems that include a variety of different power receiving devices with different properties and characteristics.

[0020] The power transfer drive signal / power transfer signal can be generated using a recurring time frame that includes a power transfer time interval during which the power transfer signal is generated and a non-power transfer time interval during which the power transfer signal is not generated, and the power transfer time interval can include at least 50%, 60%, 70%, 80%, or 90% of the recurring time frame.

[0021] The communication drive signal / communication carrier signal can be generated using a recurring time frame that includes a communication time interval during which the communication carrier signal is generated and a non-communication time interval during which the communication carrier signal is not generated. The communication time interval can include 1%, 2%, 5%, or 10% or less of the recurring time frame.

[0022] A timer expiration / timeout occurs after the initial timing duration (unless the timing duration has been changed in the interim).

[0023] References to a power transmitter operating in a connected mode, a standby mode and / or a power transfer mode may be replaced with equivalent references to a power transmitter operating in a connected phase, a standby phase and / or a power transfer phase, respectively.

[0024] This approach can utilize the communications path to provide a secondary / auxiliary power transmission path, thereby providing synergistic interoperability between communications and auxiliary power delivery.

[0025] In many embodiments, this approach allows for a reduction in the complexity of the power receiver and can in many cases eliminate the need for the power receiver to include functionality for extracting power from the power transmission signal for the power receiver's internal circuitry.

[0026] Improved control and typically dynamic performance of the auxiliary power supply is often achieved while also allowing the system to enter an ultra-low power standby phase, which consumes less power than the connected mode / phase.

[0027] In accordance with an optional feature of the invention, the mode controller circuit is configured to start a timer in response to the power transmitter entering the connected mode.

[0028] This allows for improved operation, easier implementation and / or improved performance / power transfer, especially allowing for efficient adaptation of when to enter the standby phase.

[0029] In accordance with an optional feature of the invention, the device further comprises a user interface for detecting a user action, the mode controller circuit being configured to increase the remaining time on the timer in response to detecting the user action.

[0030] This allows for particularly advantageous operation and adaptation in many embodiments, typically improving the user experience while reducing the perceived impact of implementing a low power standby phase.

[0031] According to an optional feature of the invention, the communications unit is configured to receive a request to increase a timer duration from a power receiver, and the mode controller circuit is configured to increase the remaining time of the timer in response to receiving the request to increase the timer duration from the power receiver.

[0032] This allows for particularly advantageous operation and adaptation in many embodiments, typically improving the user experience while reducing the perceived impact of implementing a low-power standby phase. This approach allows for an improved tradeoff between response time and power consumption preferences in many embodiments and scenarios.

[0033] In accordance with an optional feature of the invention, the timer duration increase request is a user action indicator indicative of a user action detected at the power receiver.

[0034] This allows for particularly advantageous operation and adaptation in many embodiments, typically improving the user experience while reducing the perceived impact of implementing a low power standby phase. This approach allows for an improved trade-off between the power receiver's response time to user actions and reduced power consumption in many embodiments and scenarios.

[0035] In accordance with an optional feature of the invention, the mode controller circuit is configured to reset the timer to an initial timing period in response to receiving a request to increase the timer duration.

[0036] This allows for improved operation, easier implementation and / or improved performance / power transfer. In particular, this approach can offer low complexity and reliable operation.

[0037] According to an optional feature of the invention, the timer duration increase request includes a timer duration increase value, and the mode controller circuit is configured to increase the remaining timer duration of the timer by an amount determined in dependence on the timer duration increase value.

[0038] This allows for improved operation, easier implementation and / or improved performance / power transfer, particularly allowing for efficient adaptation of standby operation to specific power receivers and current user actions at the power receiver.

[0039] In accordance with an optional feature of the invention, the mode controller circuit may be configured to initialize the timer with a default initial timing duration if no standby timeout indication is received from the power receiver.

[0040] This allows the power transmitter to interact with an increased variety of power receiver devices, particularly providing improved backward compatibility in many systems and scenarios.

[0041] In accordance with an optional feature of the invention, the mode controller circuit is configured to initiate a transition of the power transmitter from the standby mode to the connected mode in response to receiving a message from the power receiver.

[0042] This allows for improved operation, easier implementation and / or improved performance / power transfer.

[0043] According to an optional feature of the invention, the communications driver is configured to generate the communications drive signal at recurring time intervals in the standby mode, and the mode controller circuit is configured to set timing parameters of the recurring time intervals in response to timing messages received from the power receiver.

[0044] This allows for improved operation, easier implementation and / or improved performance / power transfer, particularly by tailoring the trade-off between power consumption in standby mode and reaction time to the specific power receiver.

[0045] In accordance with an optional feature of the invention, the mode controller circuit is configured to initialize a standby timer with a standby timing duration upon entering the standby mode, and to initiate a transition to the connected phase upon expiration of the standby timer.

[0046] This can allow for improved operation, easier implementation and / or improved performance / power transfer. In many scenarios, it can enable or facilitate additional functionality, such as allowing the power transmitter to control when the power receiver is active.

[0047] In accordance with an optional feature of the invention, the mode controller circuit is configured to determine the standby timing duration in dependence on a standby timing indicator received from the power receiver.

[0048] This allows for improved operation, easier implementation, and / or improved performance / power transfer. In many scenarios, it can enable or facilitate additional functionality, such as allowing the power transmitter to control when the power receiver activates, while ensuring that this is in accordance with the power receiver's specific preferences. This approach reduces the complexity of the power receiver, as power receiver wake-up monitoring and actions are performed by the power transmitter.

[0049] According to an optional feature of the invention, the communication unit is configured to receive standby wake-up data from the power receiver, and the mode controller circuit is configured to control the communication unit to send a wake-up message to the power transmitter when transitioning to the connected phase upon expiration of the standby timer, the wake-up message including data dependent on the standby wake-up data received from the power receiver.

[0050] This allows for improved operation, easier implementation, and / or improved performance / power transfer. This approach reduces the complexity of the power receiver, as the power receiver wake-up monitoring and actions are performed by the power transmitter.

[0051] According to one aspect of the present invention, there is provided a method for operating a power transmitter that wirelessly supplies power to a power receiver via an inductive power transmission signal, the power transmitter having a power transmission coil configured to generate the power transmission signal and a communication coil configured to generate a communication carrier signal, the method comprising the steps of: generating a power transmission drive signal by the power transmission coil to generate the power transmission signal during a power transmission phase; generating a communication drive signal by the communication coil to generate the communication carrier signal; communicating with the power receiver using modulation of the communication carrier signal; receiving a configuration message from the power receiver, the configuration message including a standby timeout indicator; controlling the power transmitter to switch between different modes, including a power transmission mode in which the power transmission signal is generated by a power transmission driver generating the drive signal, a connected mode in which no power transmission signal is generated and the communication carrier is generated 50% or more of the time, and a standby mode in which no power transmission signal is generated and the communication carrier is generated 10% or less of the time; starting a timer with an initial timing duration determined depending on the standby timeout indicator; and transitioning the power transmitter from the connected mode to the standby mode in response to expiration of the timer.

[0052] 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]

[0053] Embodiments of the present invention will now be described, by way of example only, with reference to the drawings in which: [Figure 1] 1 illustrates example elements of a power transfer system according to some embodiments of the present invention. [Figure 2] 2 illustrates example elements of a power transmitter according to some embodiments of the present invention. [Figure 3] 2 illustrates example elements of a power receiver according to some embodiments of the present invention. [Figure 4] 1A and 1B illustrate example time frames for a wireless power transfer system according to some embodiments of the present invention. [Figure 5] FIG. 2 is a diagram showing an example of elements of a power transmission path in a wireless power transmission operation. [Figure 6] 3A and 3B illustrate examples of communication carrier signals in a wireless power transfer system according to some embodiments of the present invention. [Figure 7] FIG. 1 illustrates an example of a communication and interaction protocol for a wireless power transfer system according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0054] The following description focuses on embodiments of the invention applicable to wireless power transfer systems utilizing the power transfer approach as known from the Ki 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.

[0055] 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.

[0056] The system provides an electromagnetic power transmission signal capable of inductively transmitting 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 transmission signal can be considered to correspond to an electromagnetic power transmission component representing the transfer of energy from the power transmitter to the power receiver, corresponding 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 transmission signal (apart from losses) will be zero. In some situations where a foreign object is present, the power transmission signal can be considered to include a component corresponding to the transfer of power to the foreign object, and therefore the power transmission signal can be considered to correspond to power extracted from the electromagnetic field generated by the power transmitter.

[0057] 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 power receiving coil 107 are loosely coupled, and thus the power 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 power 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 power 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 power receiving coil 107.

[0058] 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 can 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 can 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.

[0059] 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 can even exceed 2500 W for very high power applications.

[0060] The operation of power transmitter 101 and power receiver 105 is described below with particular reference to embodiments that generally conform to the standard being developed by the Wireless Power Consortium (except for modifications and enhancements described (or resulting therefrom)). In particular, power transmitter 101 and power receiver 105 conform to or are substantially compatible with elements of the Ki standard.

[0061] Many wireless power transfer systems, particularly high-power systems such as Ki, use 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 is a series resonant circuit, such that the transmitter coil 103 and receiver coil 107 can be coupled in series with corresponding resonant capacitors. The use of a resonant circuit tends to provide more efficient power transfer.

[0062] FIG. 2 illustrates elements of the power transmitter 101, and FIG. 3 shows elements of the power receiver 105 of FIG. 1 in more detail.

[0063] The power transmitter 101 has a driver 201 capable of generating a drive signal that is supplied to the transmitter coil 103, which in turn generates an electromagnetic power transfer signal by which power is transferred to the power receiver 105. The power transfer signal is provided during (at least) a power transfer time interval of the power transfer phase.

[0064] 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.

[0065] The power transmitter 101 further comprises 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 or Ki standards.

[0066] 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.

[0067] 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).

[0068] 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.

[0069] 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).

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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).

[0074] 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.

[0075] 1 to 3, communication occurs during a communication time interval during the power transfer phase. Specifically, the transmitter controller 203 may have / implement a synchronizer configured to synchronize the first communicator 205 so that communication operations (typically both data reception and transmission) occur within (typically only during) the communication time interval of the power transfer phase, i.e., the time interval allocated for communication. This can significantly improve communication performance.

[0076] This approach, in some embodiments, can utilize a time-division approach during the power transfer phase, where operations such as foreign object detection and communication and power transfer can be performed, for example, in different time intervals, thereby allowing for significantly reduced interference between them (in particular, the impact of power transfer on foreign object detection / communication).

[0077] Specifically, for a wireless power transfer system, the power transfer signal may be subject to a repeating time frame that includes at least one power transfer time interval and one communication time interval.

[0078] 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.

[0079] 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 in many cases minimized.

[0080] FIG. 3 shows some exemplary elements of the power receiver 105.

[0081] 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., is 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 or Ki standards.

[0082] 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.

[0083] The second communicator 307 is coupled to the second communication coil 309 and is configured to determine the amplitude change 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 on the communication carrier signal using other modulation formats, such as frequency modulation or phase modulation.

[0084] 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.

[0085] 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.

[0086] Thus, the second communication coil 309 is configured to transmit data to the power transmitter 101 by varying the load on the second communication coil 309 in response 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] In addition to communication, the communication carrier signal can provide an auxiliary power supply from the power transmitter to the power receiver. The auxiliary power transmission / path can provide a low power supply that can be used to power internal circuitry such as a user interface or power receiver control functions. This would be particularly suitable for providing reduced power to the power receiver outside of the power transmission phase.

[0093] The communication carrier signal can accordingly be used to provide a second, low-level power transmission path from the power transmitter to the power receiver. To support this, the power receiver includes a power extractor 311 configured to extract power from the communication carrier signal. In a specific example, the power extractor 311 can optionally extract power from an NFC carrier signal. The power extractor 311 is coupled to a load circuit 313 that can be powered by the power extracted from the communication carrier signal by the power extractor 311. The load circuit 313 may typically be control logic / support functions / circuitry of the power receiver and / or may include a user interface for the power receiver. The load circuit 313 can include or consist of elements of the power receiver controller 301 and / or the second communicator 307, for example.

[0094] Therefore, power can be supplied from the power transmitter to the power receiver via communication carrier signal / NFC carrier power harvesting. This allows for powering low-power electronics or user interfaces, such as low-voltage NFC hardware. For example, in an NFC implementation, the extracted power can be up to approximately 200mW.

[0095] 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 a user interface to be implemented to be powered entirely from 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 circuitry powered by the power transmission signal. Thus, complex high-voltage power extraction circuitry can be completely avoided. It is also well-suited for powering a power receiver outside of a power transfer phase, such as when power transfer is initiated.

[0096] The power extractor 311 is relatively simple and an example of the power extraction circuit / path is shown in FIG.

[0097] 5 shows a circuit diagram of an example element of the power path of power extractor 311. In this example, second communication coil 309 is referred to as LXR, and when it receives a communication carrier signal, a corresponding AC voltage / current is induced in the coil. Second communication coil 309 is coupled to a rectifier bridge B1, and smoothing capacitor C1 is coupled to the output of this bridge. Thus, a DC voltage is generated across capacitor C1. The magnitude of the ripple in the DC voltage depends on the size of the smoothing capacitor and the load RL being powered by power extractor 311.

[0098] Bridge B1 and smoothing capacitor C1 are coupled to load R via switch S1, which can be used to switch 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 R without a switch. Load R represents the load presented to power extractor 311 by load circuit 313.

[0099] 5 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 coil 307 can control switch S2 to provide the desired load modulation.

[0100] Therefore, the power extractor 311 can be implemented with low complexity and low cost circuitry.

[0101] In many embodiments, the wireless power transmission system and power transmitter can be configured to operate in different phases / modes.

[0102] In many embodiments, the wireless power transmission system, and thus the power transmitter and / or power receiver, can be configured to operate in different phases, particularly a power transmission phase in which a power transmission signal is generated and thus a power transmission operation to supply power to the load 303 occurs. In the power transmission phase, the power transmitter generates a power transmission drive signal and generates a power transmission signal in response. In the power transmission phase, power is supplied / transmitted to the power receiver by the power transmission signal. As described above, the power transmission signal can use a recurring time frame, and the power transmission signal is provided in a power transmission time interval, which can also include a communication time interval and / or a foreign object detection time interval. During the power transmission phase, a communication carrier signal can also be generated when communication occurs in the communication time interval.

[0103] During the power transfer phase, the power transmitter can operate in a power transfer mode in which the power transfer signal is generated by a power transfer driver, which generates a drive signal accordingly. In some embodiments, the power transfer signal / drive signal may be generated continuously during the power transfer phase, while in other scenarios it can be more intermittent, for example, interrupted by communication or foreign object detection intervals. Typically, however, the power transfer signal is generated for at least 70%, 80%, 90%, or 95% of the time during the power transfer phase.

[0104] Additionally, the wireless power transfer system can be configured to operate in a standby phase in which a power transfer signal is not generated by the power transmitter and therefore no power transfer signal is present. In the standby phase, the power transmitter operates in a standby mode and the power transfer driver 201 does not generate a power transfer drive signal, so no drive signal is provided to the transmitter coil 103. In the standby mode / phase, no power transfer signal is generated by the transmitter coil 103. In the standby phase / mode, the power transmitter and system attempt to minimize power consumption.

[0105] For example, the system can operate in a standby phase / mode in which the presence of a power receiver is not detected by the power transmitter. During this scenario, no power transmission signal is generated, and no communication carrier signal is generated. The power transmitter monitors the presence of a power receiver. In particular, the power transmitter can generate an electromagnetic detection signal at regular intervals, and if a load on this signal is detected, the power transmitter can assume that a power receiver is potentially present. The electromagnetic detection signal can be a communication carrier signal. Once a power receiver is detected, the power transmitter can transition to the configuration phase.

[0106] During the configuration phase, configuration information / data can be exchanged between the power transmitter and the power receiver. The configuration information / data can provide the other device with information about the characteristics of the power receiver and the power transmitter. Each device can adapt its operating parameters based on the exchanged configuration data. Thus, the configuration phase is used by the power transmitter and the power receiver to exchange specific information about the characteristics of the particular device, thereby adapting operation to the particular pairing of the power transmitter and the power receiver.

[0107] If the configuration phase is not successful, for example, if the power transmitter does not receive an appropriate message from the power receiver or if an explicit termination is received, the power transmitter may return to the standby phase.

[0108] Upon successful completion of configuration and communication, the power transmitter proceeds to the connection phase. During the connection phase, the power transmitter and power receiver have established communication and the devices are adapted to each other, but power transmission has not yet begun. During the connection phase, a communication carrier signal is generated, which may be present continuously during the connection phase. However, no power transmission signal is generated during the connection phase. Foreign object detection may also be performed during the connection phase. Communication may also occur between the power transmitter and the power receiver. The power receiver may often be configured to extract power from the communication carrier signal (e.g., to power internal functions of the power receiver) during the connection phase.

[0109] The connection phase can last for a significant period of time, including several hours or more, in many scenarios. For example, when a kitchen appliance equipped with a power receiver as described, such as a blender, is placed on a countertop equipped with a wireless power transmitter as described, it can go through a setup phase and then enter the connection phase in an adapted connection mode. The appliance can then remain in this state for a lengthy period corresponding to the appliance, e.g., a blender remaining on the countertop ready to be operated but not actually switched on.

[0110] In response to detecting an appropriate event, the power transmitter and power receiver can transition from the connection phase to the power transfer phase. This event is typically detected by the power receiver, which can send a message to the power transmitter to request entry into the power transfer phase. For example, if a user performs an appropriate user action, such as pressing an on button, the power receiver can responsively send a request to the power transmitter to enter the power transfer phase.

[0111] The power transmitter (and power receiver) can then proceed to transition to power transmission.

[0112] When power transmission terminates, the power transmitter and power receiver may return to the idle phase or the connected phase depending on the particular cause of the termination (e.g., if the device is switched off, the power transmitter may return to the connected phase, and if the device is removed, the power transmitter may return to the idle phase).

[0113] The setup phase and connection phase are sometimes collectively referred to as the initialization phase.

[0114] The connected phase and standby phase have in common that no power transmission / power drive signals are generated, and thus are typically pre-power phases. However, they differ in that the communication carrier signal is generated for a longer percentage of time during the connected phase than during the standby phase. Indeed, during the connected phase, the communication carrier signal may be generated continuously during the connected phase in many embodiments, or at least 50%, 60%, 70%, 80%, 90%, or 95% of the time in each embodiment. In contrast, during the standby phase, the communication carrier signal is generated for 1%, 2%, 5%, or 10% of the time in each embodiment. Thus, the communication carrier signal is generated a much higher percentage of the time (at least 5, 10, or 20 times more in each embodiment). These approaches result in much lower power consumption during the standby phase than during the connected phase, while reducing latency and enabling high-data-rate communication during the connected phase. Additionally, the power receiver's functionality can be enhanced by providing a larger auxiliary power supply.

[0115] The power transmitter can be configured to employ recurring time frames for the communication drive signal / communication carrier signal during the standby phase. The recurring time frames are divided into communication time intervals and non-communication time intervals, and the power level of the power transmission signal during the non-communication time intervals is much lower than during the communication time intervals; in fact, the communication carrier signal is typically turned off completely during the non-communication time intervals. The non-communication time intervals are sometimes referred to as low-power time intervals.

[0116] The communications driver 209 is thus configured in the described approach to generate a communications drive signal / communications carrier signal during the standby phase that employs a recurring time frame of communications time intervals and non-communications time intervals. The communications time intervals are shorter than the non-communications time intervals, but are generated at a significantly higher power / amplitude level. Indeed, in most embodiments, the communications carrier signal is generated to be present only during the communications time intervals; i.e., during the non-communications time intervals, the communications drive signal / communications carrier signal can be turned off entirely. The amplitude power level of the communications drive signal / communications carrier signal can be zero during the non-communications time intervals.

[0117] During the standby phase, the power transmitter is configured to generate short "bursts" of the communications carrier signal in response, while at other times the communications carrier signal is at a very low level, or typically turned off entirely. Figure 6 shows an example of a communications carrier signal generated during the standby phase.

[0118] During the connection phase, the communications carrier signal may be continuously present, and in some embodiments, it may also be subject to a recurring time frame, but the communications time interval in which the communications carrier signal is present occupies a majority of the recurring time frame.

[0119] The aforementioned auxiliary power supply using the communication carrier signal can be provided particularly during the standby phase (and, for example, during the setup and connection phase). Thus, the communication carrier signal during the standby (and possibly the setup and connection) phase can be used not only to provide a (typically bidirectional) communication channel between the power transmitter and the power receiver, but also to provide an auxiliary power supply to the power receiver. Thus, the auxiliary power supply during the standby phase can provide supply power that can be used to power internal circuits, such as communication functions, when the power transmission signal is not present. For example, in the conventional connection phase of a Ki system, power can be harvested from the continuous NFC communication carrier signal. However, because the communication carrier signal is generated only for a small portion of the recurring time frame, the power that can be extracted during the standby phase is typically much smaller than during the connection phase.

[0120] As previously mentioned, the standby phase is a phase in which no power receiver is detected, but in the described approach, the standby phase can also be used as a standby phase for scenarios in which the power receiver is continuously present. Thus, the power transmitter and power receiver can be configured to operate in a standby phase that supports the continued presence of the power receiver while allowing the power transmitter to power down and operate in an ultra-low power configuration.

[0121] For example, when a power receiver, such as a kitchen appliance, is placed on a power transmitter, there may be a significant delay before the power receiver / appliance is actually activated and used. In systems such as Ki, in such cases, the power transmitter and power receiver enter a connection phase and can remain in this phase until power transfer is initialized. However, such an approach consumes a non-negligible amount of power for a potentially very long time. To reduce power consumption, it may be advantageous to switch to a lower-power standby mode / phase. As another example, after a power transfer operation, the power receiver may remain in place for a subsequent power transfer operation, which may be much later (e.g., a kettle may remain in place to boil water later). In such cases, it may be desirable for the power receiver to return to the standby phase rather than returning to the connection phase, which consumes more power.

[0122] The power transmitter controller 203 is configured to control the power transmitter to transition between different modes that operate according to the functions of the corresponding phases. Thus, the power transmitter controller 203 can be configured to switch the power transmitter into a standby mode that operates according to the functions described for the standby phase, a connected mode that operates according to the functions described for the connected phase, and a power transfer mode that operates according to the functions described for the power transfer phase. The terms mode and phase can be used interchangeably. In many embodiments, the power transmitter can be configured to switch into other modes, such as a configuration mode that operates according to the functions described for the configuration phase, a foreign object detection mode that operates according to the foreign object detection phase, etc.

[0123] However, switching modes to achieve optimal performance can be challenging. Indeed, the desire to achieve very low power consumption during periods of inactivity, while supporting high functionality, responsiveness, low latency, and improved user experience and interaction, is a difficult trade-off to optimize. Power transmitters typically lack adequate criteria for determining the appropriate time to switch from the connected phase to the standby phase and when the power receiver is inactive. The ideal timing can vary greatly depending on the device. For example, setting up a cooking program for an air fryer can take a significant amount of time, during which time the power receiver is located on the power transmitter while the user is simply interacting with the power receiver's user interface. If the power transmitter decides to switch to standby due to this prolonged period of inactivity, this could occur while the user is interacting with the device's user interface, potentially causing user frustration. However, the power receiver may be a simple device that benefits from transitioning to standby mode as soon as possible when not in use. For example, in the case of a simple kettle with only one ON / OFF function, power may be activated immediately or it may take a long time before it is needed, so if there is no power transfer, it is desirable to enter the standby phase as soon as possible.

[0124] In many practical wireless power transmission systems, power-receiving devices can have user interfaces of very different complexity, ranging from simple on / off buttons to complex graphical user interfaces such as those commonly found on air fryers and food processors. Also, depending on the intended use of the power-receiving device, the time between when the device is activated and when it actually begins to provide power can vary greatly (e.g., a cordless kettle is expected to provide power almost instantly, whereas a cordless blender will require all internal components to be inserted before it can operate). Therefore, optimizing or controlling standby operation appropriately for various devices can be very difficult.

[0125] In the power transmitter of Figure 2, the power transmitter controller 203 is configured to use a configurable timing function to control standby operation. The timing function is used in conjunction with a communication protocol / process with the power receiver to adapt and set timing to provide standby operation specifically optimized for a particular power receiver.

[0126] The power transmitter of Figure 2 accordingly comprises a timer 211 coupled to the power transmitter controller 203. It will be understood that the timer 211 of Figure 2, for example, represents a functional feature that may often be implemented as part of the power transmitter controller 203. The timer 211 of Figure 2 represents a function being performed rather than a particular entity; in particular, the operations represented by the timer 211 may likewise be considered part of, and represented by, the power transmitter controller 203.

[0127] 2 is configured to start a timer 211 with a configurable timing value determined based on data transmitted from the power receiver to the power transmitter, and to switch the power transmitter from the connected phase to the standby phase when the timer expires / times out.

[0128] Specifically, the first communicator 205 receives a configuration message from the power receiver. The configuration message may typically be received during a configuration phase as part of the general communication and configuration of the power transmitter and power receiver. However, in some embodiments, the configuration message may be communicated during other phases, such as perhaps a standby phase, a connection phase, or a previous power transmission phase.

[0129] The configuration message includes a standby timeout indicator, which in many embodiments may be provided as an initial time value, but in other embodiments may be provided as a more complex indicator, such as a time value that depends on one or more parameters.

[0130] The power transmitter controller 203 can also be configured to initialize the timer 211 with an initial timing duration determined based on the received standby timeout indicator. Typically, the initial timing duration is set to the initial time value specified in the configuration message. However, in some embodiments, more complex determinations can be performed, such as modifying the received initial time value based on user settings of the power transmitter, depending on whether a previous power transmission has been performed to the power receiver, or indeed any preferred calculation that provides a desired compromise between power consumption and responsiveness to user activity.

[0131] Typically, the timer 211 is set to an initial timing duration in response to the power transmitter entering the connection phase. The timer 211 can then be started, and if the timer 211 times out / expires while the power transmitter is still in the connection mode, the power transmitter controller 203 can control the power transmitter to transition to the standby mode. The power transmitter can then be configured to enter the connection phase and then transition (back) to the standby phase after a given period that can be controlled by the power receiver, i.e., specifically adapted by the power receiver.

[0132] In some embodiments, this approach can provide a relatively low-complexity function in which a return to standby mode after entering connected mode occurs after a period corresponding to an initial timing duration, i.e., timer 211 is started and left to count down (or up) until it times out. If the power receiver is still in connected mode when this occurs, power transmitter controller 203 can transition the power transmitter into standby mode.

[0133] However, in many embodiments, the timer 211, and in particular the time remaining until expiration, can be changed in response to different events being detected.

[0134] Specifically, in some embodiments, the power transmitter may include a user interface 213 configured to detect user actions. Such a user interface may typically be simply one or more push buttons, but in some embodiments may be a more complex user interface, such as, for example, a complex touch display or a voice interface.

[0135] In some embodiments, power transmitter controller 203 can be configured to increase the remaining duration of timer 211 in response to detecting a user action. In some embodiments, the remaining period / time until timer 211 times out can be increased if any user action is detected, i.e., detecting any user action results in the timer being increased. In other embodiments, power transmitter controller 203 can be configured to increase the remaining duration only if a particular user action (or set of user actions) is detected. For example, in the case of a push button interface, in some embodiments, the remaining duration can be increased if a particular push button is pressed, or possibly if any push button is present. In other embodiments, if user interface 213 comprises, for example, a voice interface, the duration can be increased in response to a particular voice command being detected, or in other embodiments, if any voice command is detected.

[0136] Thus, in some embodiments, the delay before entering standby mode can be increased and the power transmitter can remain in a connected mode ready to begin power transmission as long as it detects that user action is still occurring, and thus the standby phase is only entered after a sufficiently long period of cessation of user activity. In other embodiments, the standby phase can be postponed by the user actively requesting it, for example by pressing a specific push button.

[0137] In some embodiments, the first communicator 205 can be configured to receive a message from the power receiver (typically during the connection phase) including a request from the power receiver to increase the timer duration. In response to receiving this message, the power transmitter controller 203 can increase the remaining time on the timer 211. Thus, the power receiver can initiate a request to postpone standby mode and communicate a message to the power transmitter, resulting in an extended standby mode. This allows for highly advantageous operation in many embodiments where the power receiver's functionality allows for dynamic control of standby operation. For example, if the power receiver needs to perform complex calculations or wait for measurements before initiating power transfer, the standby phase can be delayed to allow these to complete successfully before entering standby mode, thereby advancing the power transfer phase quickly once the calculation / measurement results are available. Otherwise, standby mode may be entered at this point.

[0138] In many embodiments, the timer duration increase request can be a user action indicator that indicates that a user action has been detected at the power receiver. For example, as described above for the power transmitter, the power receiver can have a user interface, and user activity can be detected via this user interface. If user activity is detected, the power receiver can generate a timer duration increase request and send it to the power transmitter. In some cases, the timer duration increase request can indicate, for example, detected user activity. In other embodiments, it can simply indicate that (any) user activity has been detected.

[0139] Thus, in response to any detected event, the time remaining until timer 211 times out can be increased in some embodiments. In some embodiments, detection of an event, such as detection of a user action or activity, results in power transmitter controller 203 resetting the timer to its initial timing duration. For example, whenever the power transmitter detects a user action or receives a message from the power receiver indicating detection of a user action, timer 211 can be reset to its original value and restart the countdown. This provides very efficient and user-friendly operation in many scenarios, and in particular allows for low-complexity operation and a very advantageous dynamic trade-off between power consumption and user action response time.

[0140] In some embodiments, the remaining time may be increased by a predetermined amount, e.g., a fixed number of seconds. For example, each time a push button is detected, the remaining time may be increased by 5 seconds. In other embodiments, the increase in the remaining period may be variable.

[0141] In some embodiments, the power transmitter controller 203 can be configured to receive a timer duration increment value from the power receiver and increase the remaining timer duration by an amount determined from the timer duration increment value. Typically, the power transmitter controller 203 is configured to set the remaining duration to the timer duration increment value or to increase it by a value equal to the timer duration increment value. Thus, in some embodiments, the power receiver can control the postponement of the standby phase, thereby closely matching the operations performed by the power receiver. For example, if the power receiver is waiting for a measurement before deciding whether to proceed with the power transmission phase, it can send a timer duration increment request with a timer duration increment value that reflects the expected time the measurement will take. In this way, the power transmitter can postpone the start of standby mode by an appropriate amount of time.

[0142] Thus, the power transmission system can be configured to enter a very low-power standby phase, with this operation controlled and adapted by the individual power receivers. This approach can be further configured to initialize a timer with a default initial timing duration if no standby timeout indicator is received from the power receiver. Thus, the power transmitter can enter standby mode after the default duration after entering connected mode, unless a message providing the initial timing duration is received from the power receiver. This approach can therefore enable compatibility with a wide range of power receivers, including both power receivers that have the capability to provide dynamic adaptation of the period before entering the standby phase and, e.g., conventional power receivers, that do not have such capability. This approach can be easily introduced into existing systems, allowing for a high degree of backward compatibility.

[0143] The power transmitter of FIG. 2 is accordingly configured to enter a very low power standby mode of operation in a dynamic manner that can be adapted to a particular power receiver.

[0144] In many embodiments, the power transmitter controller 203 can be configured to further transition the power transmitter from the standby mode to the connected mode in response to receiving a message from the power receiver. This message can specifically be a wake-up message indicating that the power receiver may soon be entering a power transmission phase. For example, if the initiation of power transmission is based on a measurement made based on extracting power from a communication carrier signal when the communication carrier signal is continuously present, the power receiver can send a wake-up message to the power transmitter, which can then proceed to transition from the standby mode to a connected mode in which the communication carrier signal is continuously generated. The power transmitter controller 203 can also initialize the aforementioned timer 211. Depending on the result of the measurement, the power receiver may then enter a power transmission phase or return to inactivity, resulting in the timer 211 expiring after an appropriate duration and the power transmitter returning to the standby mode.

[0145] In some embodiments, the power transmitter controller 203 may proceed to initialize a standby timer with a standby timing duration when entering standby mode. Thus, when entering standby mode, the power transmitter controller 203 may be configured to set a new timer that, upon expiration, initiates a transition to the connected phase. In some embodiments, the power transmitter controller 203 may automatically transition from standby mode back to connected mode after a given period of time has elapsed.

[0146] In many embodiments, the power receiver can transmit a standby timing indicator to the power transmitter. In response to receiving this standby timing indicator, the power transmitter controller 203 can determine an appropriate standby timing duration for which the power transmitter controller 203 sets the standby timer when entering standby mode. Thus, the power receiver can control the amount of time the power transmitter remains in low-power standby mode before automatically waking up and transitioning to connected mode.

[0147] Such an approach allows for particularly advantageous performance, for example, if the power receiver can prepare for the function, set its timer, and then completely power down. The power transmitter can then enter a connected mode after a predetermined delay, for example, with a continuously generated communication carrier signal, waking up the power receiver with the auxiliary power supply. Initialization of a new power transmission operation can then proceed.

[0148] For example, a bread maker can be configured to be inactive for a given period of time to allow dough to rise. In the described approach, this can be supported by a power supply suspension that is controlled by the power receiver but does not require the power receiver's power consumption or functionality to be active during the off / standby period. Rather, the initiative to restart after a desired suspension is transferred to a power transmitter that can support the required functionality with low complexity. Furthermore, such operation can be supported using a general-purpose power transmitter that is not specifically designed to provide such functionality for a particular power receiver.

[0149] In some embodiments, the power receiver may send further data to the power transmitter before entering standby mode, which may be sent back to the power receiver when entering connected mode after a pause.

[0150] Thus, in some embodiments, the power receiver can be configured to transmit standby wake-up data to the power receiver prior to pausing, for example, as part of a configuration phase to the power transmitter before the power transmitter enters standby mode.

[0151] This approach can therefore provide efficient standby operation, particularly for power receiving devices / appliances whose functionality includes periods when no power is required, for example. The system allows the power receiving device and power transmitter to enter a standby mode, and the power receiver also provides a period before needing to wake up again.

[0152] For example, suppose a bread maker kneads dough and needs to proof it for 30 minutes. The power receiver can send a wake-up timer (standby duration) to the power transmitter with a value of 30 minutes. Additionally, it can include some data related to the bread-making procedure, such as the status of the bread maker. After 30 minutes, the power transmitter can reactivate the system and return the received data about the status of the power receiver (and possibly the received timing values) to the power receiver. The bread maker can then continue the program and know where to start from the received data. Thus, a complete power-down of the bread maker is possible. During the standby period, the power transmitter continues to communicate to check for system changes, but less frequently. During the bread maker's standby interval, in some embodiments, it is possible to use another device, as long as the bread maker is returned before the end of the pause. This can also be displayed on the transmitter's user interface. If the bread maker is not repositioned in time, the power receiver can decide whether to continue the program.

[0153] When the power transmitter transitions from standby mode to connected mode, the power transmitter can send a wake-up message to the power receiver. The wake-up message can include data that depends on standby wake-up data previously received from the power receiver. For example, the standby wake-up data, in some embodiments, can simply repeat the previously received standby wake-up data, i.e., the power transmitter can send the previously received data back to the power receiver. Indeed, in some embodiments, the power transmitter can simply blindly read the stored data and send it back, without any knowledge of the meaning of the received standby wake-up data. Thus, in some embodiments, the power receiver can effectively use the power transmitter as a data store for storing data during standby / suspend periods in such cases. This approach can support very low-complexity power receivers, such as power receivers that do not include sufficient non-volatile memory to store all data.

[0154] The described approach enables a highly efficient standby system that can reduce power consumption to very small levels while providing appropriate user interaction and responsiveness. This can provide an approach that is highly flexible and adaptable to specific power-receiving devices, including the user actions and interfaces typically associated with such power-receiving devices.

[0155] The described approach is suitably configured to accommodate, in many embodiments, the fact that different power-receiving devices / appliances may have significantly different preferred times for entering standby mode (e.g., 30 seconds for a kettle, 5 minutes for a blender), allowing, for example, an appliance manufacturer to specify a preferred standby timeout in the appliance settings, which the power transmitter can read and set during system setup to configure the standby timer.

[0156] The power transmitter may use such a feature in many embodiments to go into standby mode if power transmission does not begin within a period corresponding to the standby timeout.

[0157] While in some embodiments the power receiver can be configured to specify any initial timing duration, including perhaps an infinite time (so the power transmitter does not switch to standby mode), in many embodiments the initial timing duration can be limited to a given range, typically by, for example, an appropriate standards body or regulatory committee. In this case, the power transmitter can limit the initial duration of the timer to a value defined by the standards or regulatory committee and notify the power receiver of that limit.

[0158] In many embodiments, after configuration is complete and the power transmitter enters connected mode, the system can enter a state waiting to enable power transmission and switch to the power transmission phase. In this state, the user interface of the power receiving device is powered via the auxiliary power supply using a communications carrier signal and is therefore active and can be operated by the user. Each time the user operates the user interface, the power receiving device can register it and notify the power transmitter that a user operation is in progress. The power transmitter can adjust or reset the remaining timing duration accordingly, possibly depending on the characteristics of the user action (e.g., which user action was performed) indicated by the data transmitted to the power transmitter.

[0159] In a practical embodiment, the power receiving device provides a precise time that depends on the frequency and type of user actions to extend the standby timeout.

[0160] Figure 7 shows an example of a suitable communication exchange / protocol that can be used. The exchanges and actions include: a. The power receiver provides the desired standby timeout when placed on the power transmitter or when returning from standby. b. The power transmitter sets the standby timer with the standby timeout value received from the power receiver and transitions the system to the Connected Phase. c. During connection, the power receiver notifies the power transmitter when the user interacts with the user interface. d. The power transmitter resets the standby timer if it receives a command from the power receiver indicating that the user has operated the user interface. e. The power transmitter will put the system into standby after the standby timeout expires.

[0161] When a power-receiving device is in standby mode, there should preferably be a means to reactivate the power receiver. The power transmitter can determine if there is a change in the system in various ways, such as object detection or communication. Object detection means that a physical change must occur in the system, such as moving a device or inserting another object. This is typically not user-friendly, so communication-based wake-up is often preferred. The fastest way to detect a change is if a flag is present in the configuration data (NDEF message) from the power receiver. The power receiver can use such a flag to indicate whether it wants to be reactivated or remain in standby mode. This flag can be activated by a user action, such as pressing a button. Because the NDEF message is sent during communication setup, it is short-lived and consumes limited power.

[0162] When the system is in standby mode and a power receiver is present, the amount of NFC communication by the power transmitter can be reduced because no changes to the system are expected (the power receiver is not moved, no other objects are placed thereon). For example, the power transmitter can check for changes every 100-200 milliseconds when the system is in standby mode without the power receiver present. However, in standby mode with the power receiver stationary, this can often be reduced to, for example, once every 1-10 seconds. Such an approach allows for very significant power reductions because the carrier signal is only needed for very short time intervals that are very infrequent. The duration of the active carrier signal time slot can, in some cases, be set in response to a message from the power receiver. For example, it can be set by the power receiver during a configuration phase, thereby adapting to the specific power receiving device and the functions provided by it. This allows for significant power reductions in the system with only a minor impact on the user experience. If a change is detected during the standby phase, for example if it is detected that a power receiving device has been removed, then the frequency of the communication carrier signal can be increased, for example returned to a typical interval suitable for detecting a new power receiver, for example returned to a time interval of the communication carrier signal at intervals of about 100-200 ms.

[0163] Thus, in some embodiments, the communication driver 209 can be configured to generate a communication drive signal at recurring time intervals when in standby mode, as illustrated, for example, in Figure 6. In such embodiments, the power transmitter controller 203 can be configured to set timing parameters such as the frequency / duration of the recurring time intervals based on timing messages received from the power receiver.

[0164] It will be appreciated 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 also be performed by the same processor or controller. References to specific functional units or circuits should therefore be seen merely as references to suitable means for providing the described functionality, rather than to indicative of a strict logical or physical structure or organization.

[0165] The present invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The present invention may optionally be implemented at least in part as computer software running on one or more data processors and / or digital signal processors. The elements and components of embodiments of the present 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 present invention may be implemented in a single unit, or may be physically and functionally distributed between different units, circuits, and processors.

[0166] 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.

[0167] It will be understood that the reference to a 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 a preferred value can be used in place of a reference to, for example, a first value.

[0168] 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. Furthermore, 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.

Claims

1. 1. 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 transfer driver configured to generate a power transfer drive signal for the power transfer coil to generate the power transfer signal during a power transfer phase; 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, the communication unit configured to receive a configuration message from the power receiver, the configuration message having a standby timeout indicator; and a mode controller configured to control the power transmitter to switch between different modes including a power transmission mode in which the power transmission signal is generated by the power transmission driver that generates the drive signal, a connection mode in which the power transmission signal is not generated and the communication carrier signal is generated 50% or more of the time, and a standby mode in which the power transmission signal is not generated and the communication carrier signal is generated 10% or less of the time; wherein the mode controller in the connected mode is configured to start a timer with an initial timing duration determined in dependence on the standby timeout indicator, and transition the power transmitter from the connected mode to the standby mode in response to expiration of the timer.

2. The power transmitter of claim 1 , wherein the mode controller is configured to start a timer in response to the power transmitter entering the connected mode.

3. 3. The power transmitter of claim 1, further comprising a user interface for detecting a user action, wherein the mode controller is configured to increase the remaining time of the timer in response to detecting the user action.

4. 4. The power transmitter of claim 1, wherein the communication unit is configured to receive a timer duration increase request from the power receiver, and the mode controller is configured to increase the remaining time of the timer in response to receiving the timer duration increase request from the power receiver.

5. 5. The power transmitter of claim 4, wherein the timer duration increase request is a user action indicator indicative of a user action detected at the power receiver.

6. 6. The power transmitter of claim 4 or 5, wherein the mode controller is configured to reset the timer to the initial timing duration in response to receiving a request to increase the timer duration.

7. 7. The power transmitter of claim 4, wherein the timer duration increase request includes a timer duration increase value, and wherein the mode controller is configured to increase the remaining timer duration of the timer by an amount determined in dependence on the timer duration increase value.

8. 8. The power transmitter of claim 1, wherein the mode controller is configured to initialize the timer with a default initial timing duration if the mode controller has not received the standby timeout indication from the power receiver.

9. 8. The power transmitter of claim 1, wherein the mode controller is configured to initiate a transition of the power transmitter from the standby mode to the connected mode in response to receiving a message from the power receiver.

10. 10. The power transmitter of claim 1, wherein the communication driver is configured to generate the communication drive signal at recurring time intervals when in the standby mode, and the mode controller is configured to set timing parameters of the recurring time intervals in response to timing messages received from the power receiver.

11. 11. The power transmitter of claim 1, wherein the mode controller is configured to initialize a standby timer with a standby timing duration upon entering the standby mode and to initiate a transition to the connected phase upon expiration of the standby timer.

12. 12. The power transmitter of claim 11, wherein the mode controller is configured to determine the standby timing duration dependent on a standby timing indicator received from the power receiver.

13. 13. The power transmitter of claim 11 or 12, wherein the communication unit is configured to receive standby wake-up data from the power receiver, and the mode controller is configured to control the communication unit to send a wake-up message to the power receiver when transitioning to the connection phase upon expiration of the standby timer, the wake-up message including data dependent on the standby wake-up data received from the power receiver.

14. 1. A method of operating a power transmitter that wirelessly supplies power to a power receiver via an inductive power transmission signal, the power transmitter having a power transmission coil configured to generate the power transmission signal and a communication coil configured to generate a communication carrier signal, the method comprising: generating a power transfer drive signal for the power transfer coil to generate the power transfer signal during a power transfer phase; generating a communication drive signal for causing the communication coil to generate a communication carrier signal; communicating with the power receiver using modulation of the communications carrier signal; receiving a configuration message from the power receiver, the configuration message including a standby timeout indicator; controlling the power transmitter to switch between different modes including a power transmission mode in which the power transmission signal is generated by the power transmission driver that generates the drive signal, a connection mode in which the power transmission signal is not generated and the communication carrier signal is generated 50% or more of the time, and a standby mode in which the power transmission signal is not generated and the communication carrier signal is generated 10% or less of the time; starting a timer with an initial timing duration determined in dependence on said standby timeout indicator; transitioning the power transmitter from the connected mode to the standby mode in response to expiration of the timer; A method having the following.

15. A wireless power transmission system for wirelessly supplying power to a power receiver, the wireless power transmission system comprising a power transmitter according to any one of claims 1 to 13.

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