Wireless Power Transmission

Abstract

A wireless power transmitter 101 having an output circuit 203, 103 includes a transmitter coil 103 to which a drive signal generated by the drive circuit 201 is applied, generating a power transmission signal. A power loop controller 209 implements a power control loop for controlling the drive signal to adjust the power level of the power transmission signal in response to a power control error message received from a power receiver 105. A mode storage device 213 stores a plurality of power level modes for the power receiver, each power level mode being associated with a reference power level for the power transmission signal. In response to receiving a mode request message, a mode circuit 211 adapts the drive signal to set the power level of the power transmission signal to a first reference value, the first reference value corresponding to the reference power level of the first power level mode indicated in the mode request message.

Description

Technical Field

[0001] The present invention relates to the operation of a wireless power transmission system, and more particularly, but not limited to, a method for supporting varying power levels in a wireless power transmission system such as Qi.

Background Art

[0002] Most current electrical products require dedicated electrical contacts to supply power from an external power source. However, this tends to be impractical and requires the user to physically insert a connector or otherwise establish a physical electrical contact. Typically, the power requirements also vary greatly, and currently, most devices are provided with a dedicated power source, and as a result, a typical user will have a number of different power sources, each power source being specific to a particular device. However, the use of a built-in battery can avoid the need for a wired connection to a power source during use, but this only provides a partial solution as it requires recharging (or replacing) the battery. Also, using a battery can substantially increase the weight, potential cost, and size of the device.

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

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

[0005] Such a configuration enables wireless power transmission to the device without the need for a wired or physical electrical connection. In fact, to recharge or supply power from an external source, the device can simply be placed adjacent to or on top of the transmitter coil. For example, the power transmitter can be configured to have a horizontal plane on which the device can simply be placed to supply power.

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

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

[0008] Qi was originally low-power wireless power transmission defined in version 1.0 and was actually limited to lower power levels of less than 5W. This has been extended to higher power levels in subsequent versions, providing compliance tests for power levels up to 15 W in version 1.2, for example.

[0009] To control and adapt power transmission, a wireless power transmission system typically implements a power control loop. During power transmission, the power receiver continuously sends power error control messages to the power transmitter, and the power transmitter responds by increasing or decreasing the power level accordingly. Such a power control loop typically provides an efficient way for the power receiver to control the level of power transmitted from the power transmitter. However, the exact design of such a power control loop is difficult and involves many trade-offs that inherently result in sub-optimal performance. For example, while it is desirable for the power control loop to respond quickly to changes in the required power, at the same time, it is desirable for the loop to be stable and resilient to noise.

[0010] Accordingly, an improved approach for wireless power transmission would be particularly advantageous for enabling increased flexibility, reduced cost, reduced complexity, improved support for a large power range, improved transient power performance, improved adaptability, backward compatibility, improved power transmission operation, and / or improved performance.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] Therefore, the present invention preferably seeks to alleviate, reduce or eliminate one or more of the above disadvantages, either alone or in any combination.

MEANS FOR SOLVING THE PROBLEMS

[0012] According to one aspect of the present invention, there is provided a power transmitter for wirelessly supplying power to a power receiver via an electromagnetic power transmission signal, the power transmitter comprising: a receiver for receiving a message from the power receiver; an output circuit comprising a transmitter coil for generating a power transmission signal in response to a drive signal applied to the output circuit; a driver circuit for generating the drive signal; a power loop controller implementing a power control loop for controlling the drive signal to adjust the power level of the power transmission signal, the power control loop being configured to change the power level of the power transmission signal in response to a power control error message received from the power receiver; a mode storage device configured to store a plurality of power level modes for the power receiver, each power level mode being associated with a reference power level of the power transmission signal; and a mode circuit configured to adapt the drive signal to set the power level of the power transmission signal to a first reference value in response to receiving a mode request message, the first reference value corresponding to the reference power level of a first power level mode among a plurality of power level modes indicated in the mode request message.

[0013] In many scenarios, the present invention can provide improved performance and / or improved power transmission. In many embodiments, it can enable improved and more efficient power transmission across a variety of power levels. This approach can support, enable, improve, or facilitate high-power wireless power transmission in many embodiments.

[0014] In many embodiments, improved switching between different power levels can be achieved, and in particular, transient performance can be improved. This approach can enable the system to utilize the advantages provided by an accurate power control loop while mitigating some of the drawbacks of such loops. In particular, a stable and reliable power control operation can be combined with fast transient performance.

[0015] The use of specific power level modes and messaging from the power receiver may, in particular, enable the power control loop performance and constraints to be overridden at specific times in order to provide fast transient performance.

[0016] The reference power level for a power level mode can be represented, for example, by any parameter of a drive signal or a transmitter coil signal that affects the power level of the power transmission signal, specifically, by the amount of power transmitted to the power receiver. The reference power level can specifically be the current, voltage, frequency, power, duty cycle and / or active duration (burst mode) of the drive signal, and / or the current, voltage, frequency, power, duty cycle, and / or active duration (burst mode) of the signal of the transmitter coil. In many embodiments, the reference power level may be indicated by the coil current of the transmitter current.

[0017] The reference power level for a power level mode may be a reference power level parameter that affects and / or reflects the power level of the power transmission signal.

[0018] Similarly, the first reference value can be represented by any parameter of a drive signal or a transmitter coil signal that affects the power level of the power transmission signal, specifically, the amount of power transmitted to the power receiver. The first reference value can specifically be the current, voltage, frequency, power, duty cycle and / or active duration (burst mode) of the drive signal, and / or the current, voltage, frequency, power, duty cycle and / or active duration (burst mode) of the signal of the transmitter coil. In many embodiments, the first reference value may be indicated by the coil current of the transmitter current. The first reference value may be for the same parameters as the reference power level of the power level mode indicated in the mode request message, or for different parameters (in which case the mode circuit can convert between the parameters).

[0019] The power loop controller may be configured to control the drive signal by adapting its parameters that affect the power level of the power transmission signal, such as the current, voltage, frequency, power, duty cycle, and / or active duration (burst mode) of the drive signal.

[0020] The parameters that affect the power level of the power transmission signal may specifically have a one-to-one monotonic relationship with the power level of the power transmission signal (at least within the operating range).

[0021] A receiver for receiving a message from the power receiver may sometimes be called a ( message receiver for receiving a message from the power receiver).

[0022] According to an optional feature of the present invention, the period for adapting the drive signal to set the power level of the power transmission signal to a first reference value is less than the time constant of the power control loop.

[0023] This approach may enable a faster adaptation of the power transmission operation to changes in the power transmission operation.

[0024] According to an optional feature of the present invention, the mode storage device is configured to store a plurality of parameters related to at least one power level mode, the plurality of parameters including at least one reference power level representing the power level of the power transmission signal and at least one parameter value for at least one of the drive signal and the signal of the transmitter coil, the at least one parameter value being a value for at least one of the drive signal and the signal of the transmitter coil with respect to the power level of the power transmission signal indicated by the reference power level.

[0025] This can provide improved performance in many embodiments. For example, the power transmitter can store both reference power levels in the form of power extracted by the power receiver. Further, the power transmitter can store signal parameter values of a drive signal or a transmitter coil signal that result in corresponding power levels of the power transmission signal. For example, it can store the frequency of the drive signal that generates a desired power level. This can be considered equivalent to a mode storage device that stores multiple reference power levels for a given power level mode, or it will be understood that the stored reference power levels for a given power level mode may comprise multiple elements.

[0026] According to an optional feature of the present invention, the power transmitter further comprises a detection circuit that detects a power transmission anomaly in response to a comparison between the current power level of the power transmission signal and a reference power level for the current power level mode among a plurality of power level modes.

[0027] This approach can enable improved operation, and in particular, can enable anomalies such as fault situations to be detected, thereby enabling the system to respond to such situations.

[0028] In some embodiments, the detection circuit is configured to change a parameter of the power transmission in response to detection of a power transmission anomaly.

[0029] This can provide improved performance in many embodiments and enables the system to compensate for anomalies such as potential faults. Specifically, the detection circuit can reduce the maximum power limit of the power transmission signal and / or terminate ongoing power transmission.

[0030] According to an optional feature of the present invention, during the initialization phase in which the power receiver passes through at least some power level modes, the mode circuit is configured to determine a reference power level for at least some of the plurality of power level modes in relation to at least one of the parameter values of the drive signal and the parameter values of the power transmission signal characteristics, and the mode storage device is configured to store the reference power levels for at least some of the power level modes.

[0031] This can provide particularly efficient operation in many embodiments and scenarios, for example, it can enable adaptation to different power receivers without the power transmitter requiring pre-stored information.

[0032] The parameter values of the drive signal and / or the transmitter coil signal may be measured parameters or may be parameters set by the power transmitter during operation in the initialization phase. For example, the parameter values may be the frequency, current, voltage, duty cycle, and power of the drive signal and / or the transmitter coil signal during operation in the power level mode during the initialization phase.

[0033] The measured values of the drive signal characteristics and the measured values of the power transmission signal characteristics may be measured values that enable the determination of appropriate parameters, such as the transmitter coil current, for indicating the reference power level.

[0034] According to an optional feature of the present invention, the initialization phase is before the power transmission phase.

[0035] This can provide improved operation in many embodiments.

[0036] According to an optional feature of the present invention, the receiver is configured to receive a power receiver setting message from the power receiver, the power receiver setting message including power receiver setting parameters, and the mode circuit is configured to determine a reference power level for at least one of a plurality of power level modes according to the power receiver setting characteristics. This can provide improved operation in many embodiments. In many embodiments and scenarios, the power transmitter can be made to accurately estimate the appropriate reference power level for a particular power receiver. This approach enables the power transmitter to adapt to a particular power receiver.

[0037] According to an optional feature of the present invention, the power receiver setting parameters include at least one of a power receiver ID, a power receiver type ID, a power receiver coil characteristic, a power receiver coil dimension characteristic, and a power receiver coil inductance characteristic.

[0038] These parameters can provide particularly advantageous adaptation in many embodiments.

[0039] According to an optional feature of the present invention, the mode circuit is configured to determine a coupling coefficient between the power transmitter coil and the power receiver coil of the power receiver based on the power receiver setting parameters, and to determine a reference power level for at least one of the power level modes based on the coupling coefficient.

[0040] This can provide particularly advantageous operation and / or performance in many embodiments and scenarios.

[0041] According to an optional feature of the present invention, the mode circuit is configured to determine a power transfer function between at least one of the parameters of the drive signal and the parameters of the transmitter coil signal and the output power of the power receiver based on the power receiver setting parameters, and to determine a reference power level for the at least one of the power level modes based on the power transfer function.

[0042] This can provide particularly advantageous operation and / or performance in many embodiments and scenarios.

[0043] According to any feature of the present invention, the mode storage device is configured to store a set of power level modes for different power receivers, and the mode circuit is configured to select among the set of power level modes according to the ID display received from the power receiver. This can provide improved operation in many embodiments.

[0044] According to an optional feature of the present invention, the mode request message includes a timing index, and the mode circuit is configured to adapt the timing for setting the power level of the power transmission signal according to the timing index.

[0045] This can provide particularly advantageous operation and / or performance in many embodiments and scenarios. The timing index can indicate one or more changes in the power level mode by the power receiver.

[0046] According to an optional feature of the present invention, the mode request message is received during the power transmission phase.

[0047] This can provide particularly advantageous operation and / or performance in many embodiments and scenarios.

[0048] According to another aspect of the present invention, there is provided an operating method for a power transmitter for wirelessly supplying power to a power receiver via an electromagnetic power transmission signal, the power transmitter having the output circuit including a transmitter coil for generating a power transmission signal in response to a drive signal applied to the output circuit, the method comprising the steps of: receiving a message from the power receiver; generating a drive signal; operating a power control loop for controlling the drive signal to adjust a power level of the power transmission signal, the power control loop being configured to apply a change to the power level of the power transmission signal in response to a power control error message received from the power receiver; storing, in a mode storage device, a plurality of power level modes for the power receiver, each power level mode being associated with a reference power level for the power transmission signal; and adapting the drive signal to set the power level of the power transmission signal to a first reference value in response to receiving a mode request message, the first reference value corresponding to a reference power level for a first power level mode among the plurality of power level modes indicated in the mode request message.

[0049] According to another aspect of the present invention, there is provided a wireless power transmission system including a power transmitter for wirelessly supplying power to a power receiver via an electromagnetic power transmission signal, the power transmitter including a receiver for receiving a message from the power receiver, an output circuit including a transmitter coil for generating the power transmission signal in response to a drive signal applied to the output circuit, a drive circuit for generating the drive signal, and a power loop control device for controlling the drive signal to adjust the power level of the power transmission signal, the power control loop being configured to change the power level of the power transmission signal in response to a power control error message received from the power receiver, a mode storage device configured to store a plurality of power level modes for the power receiver, each power level mode being associated with a reference power level for the power transmission signal, and a mode circuit configured to adapt the drive signal to set the power level of the power transmission signal to a first reference value in response to receiving a mode request message, the first reference value corresponding to a reference power level of a first power level mode among a plurality of power level modes indicated in the mode request message.

[0050] These and other aspects, features, and advantages of the present invention will become apparent from and will be elucidated with reference to the embodiments described hereinafter.

Brief Description of the Drawings

[0051] Embodiments of the present invention will be described by way of example only with reference to the drawings.

Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0052] The following description focuses on embodiments of the present invention applicable to a wireless power transmission system that utilizes a power transmission approach known from the Qi standard. However, it will be understood that the present invention is not limited to this application and may be applied to many other wireless power transmission systems.

[0053] FIG. 1 shows an example of a power transmission system according to some embodiments of the present invention. The power transmission system includes a power transmitter 101 that includes (or is coupled to) a transmitter coil / inductor 103. The system further includes a power receiver 105 that includes (or is coupled to) a receiver coil / inductor 107.

[0054] The system provides an electromagnetic power transmission signal that can inductively transmit power from the power transmitter 101 to the power receiver 105. Specifically, the power transmitter 101 generates an electromagnetic signal, and the electromagnetic signal is a transmitter coil or inductor 103 (typically in the form of a resonant circuit or a tank circuit) It is propagated as magnetic flux by (being part of the state output circuit). The power transmission signal may correspond to an electromagnetic power transmission component representing energy transmission from the power transmitter to the power receiver, and may be considered to correspond to a component of the generated electromagnetic field that transmits power from the power transmitter to the power receiver. For example, when 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 potentially generate an electromagnetic field with a high electric field strength, but the power level of the power transmission signal would be zero (apart from losses). In some situations where foreign objects are present, the power transmission signal can be considered to include a component corresponding to power transmission to the foreign object, and thus the power transmission signal can be considered to correspond to the power extracted from the electromagnetic field generated by the power transmitter.

[0055] The power transmission signal may typically have a frequency between about 20 kHz and about 500 kHz, and for a Qi-compatible system, it is typically in the range of 95 kHz to 205 kHz (or for example, for high-power kitchen applications, the frequency may typically be in the range of 20 kHz to 80 kHz). The transmitter coil 103 and the receiver coil 107 are loosely coupled, and thus the receiver coil 107 picks up (at least part of) the power transmission signal from the power transmitter 101. Therefore, power is transmitted from the power transmitter 101 to the power receiver 105 via wireless inductive coupling from the transmitter coil 103 to the receiver coil 107. The term power transmission signal is mainly used to refer to the inductive signal / magnetic field (magnetic flux signal) between the transmitter coil 103 and the power receiver coil 107.

[0056] In an embodiment, the power receiver 105 is a power receiver that receives power specifically via the receiver coil 107. However, in other embodiments, the power receiver 105 may include a metal element such as a metal heating element, in which case the power transmission signal directly induces eddy currents that cause direct heating of the element.

[0057] The system is configured to transmit substantial power levels. Specifically, in many embodiments, the power transmitter can support power levels exceeding 500 mW, 1 W, 5 W, 50 W, 100 W, or 500 W. For example, in the case of Qi - compliant applications, power transmission is typically in the power range of 1 - 5 W for low - power applications (baseline power profile), up to 15 W for Qi standard version 1.2, up to 100 W for high - power applications such as power tools, laptops, drones, robots, etc., and for very high - power applications such as high - power applications supported by the cordless kitchen standard developed by the Wireless Power Consortium, it can exceed 100 W and be in the range exceeding 1000 W.

[0058] In the following, the operation of the power transmitter 101 and the power receiver 105 will be described with particular reference to embodiments that generally comply with the Qi standard (except for the modifications and extensions described (or resulting) herein) or are suitable for the high - power kitchen specifications developed by the Wireless Power Transmission Consortium. In particular, the power transmitter 101 and the power receiver 105 comply with, or are substantially compatible with, the elements of Qi standard versions 1.0, 1.1, or 1.2, or are suitable for higher - power cordless kitchen specifications (excluding the modifications and extensions described (or resulting) herein).

[0059] FIG. 2 shows the elements of the power transmitter 101 of FIG. 1 in more detail.

[0060] The power transmitter 101 includes a driver 201 that can generate a drive signal, which is supplied to an output circuit that is a resonant circuit formed by the transmitter coil 103 and the transmitter capacitor 203 in this example. The transmitter coil 103 is driven by the drive signal, thereby generating an electromagnetic field. Thus, an electromagnetic power transmission signal that provides power transmission to the power receiver 105 is generated. The power transmission signal is supplied (at least) during the power transmission phase.

[0061] Driver 201 is typically a drive circuit in the form of an inverter that generates an alternating current signal from a direct current voltage. The output of driver 201 is usually a switch bridge that generates a drive signal by appropriate switching of the switches of the switch bridge. FIG. 3 shows a half-bridge switch bridge / inverter. Switches S1 and S2 are controlled so as not to close simultaneously. Alternately, S1 is closed while S2 is open, and S2 is closed while S1 is open. The switches are opened and closed at a desired frequency, thereby generating an alternating current signal at the output. Typically, the output of the inverter is connected to the transmitter inductor via a resonant capacitor. FIG. 4 shows a full-bridge switch bridge / inverter. Switches S1 and S2 are controlled so as not to close simultaneously. Switches S3 and S4 are controlled so as not to close simultaneously. Alternately, S1 and S4 are closed while S2 and S3 are open, and S2 and S3 are closed while S1 and S4 are open, thereby generating a square wave signal at the output. The switches are opened and closed at a desired frequency.

[0062] In some implementations, S1 and S3 may be open and S2 and S4 may be closed during a part of the cycle, and vice versa in another part of the cycle. This is known as phase control. Such an approach generates a square wave having a zero level in between. The drive circuit is implemented using discrete electronics, and the output circuit is formed by solid state switches such as transistors. However, it will be understood that other implementations are possible, including forming the output circuit using, for example, integrated switches or mechanical switches.

[0063] The drive circuit can be implemented as an integrated circuit, such as an application specific integrated circuit (ASIC) for example. In some embodiments, the circuit may be implemented as a programmed processing unit, such as firmware or software executed on a suitable processor, such as a central processing unit, a digital signal processing unit, or a microcontroller for example. In such embodiments, it will be appreciated that the processing unit may include memory on or external to the substrate, a clock drive circuit, an interface circuit, a user interface circuit, and the like. Such circuits may also be implemented, as part of the processing unit, as an integrated circuit and / or as discrete electronic circuits.

[0064] Accordingly, driver 201 generates a drive signal for the output resonant circuit and thus for transmitter coil 103. The drive signal causes current to flow through the transmitter coil, thereby generating an electromagnetic power transmission signal. The drive signal typically has a (substantially) constant voltage amplitude for a given power transmission configuration. In the example, this constant voltage amplitude is achieved by setting a constant rail voltage for the output circuit of the driver, i.e., the rail voltage V for the bridges of FIGS. 3 and 4 is constant for a given power transmission configuration. Switching by the bridge transistors switches the output voltage between 0 and V for a half bridge and between V and -V for a full bridge. Thus, in the example, the power transmitter can set the rail voltage to be constant for any given power transmission setting, but (optionally) varying between power transmission settings.

[0065] Power transmitter 101 further includes a power transmitter controller 205 configured to control the operation of power transmitter 101 according to a desired operating principle. Specifically, power transmitter 101 can include many of the functions required to perform power control in accordance with the Qi standard, including interacting with the power receiver, providing a user interface, etc., as appropriate for a particular application and standard.

[0066] The power transmitter 101 further includes a first communication device 207 configured to receive data and messages from the power receiver 105 (as will be understood by those skilled in the art, a data message can provide information of one bit or multiple bits). In the example, the power receiver 105 is configured to load-modulate the power transmission signal generated by the transmitter coil 103, and the first communication device 207 is configured to sense the voltage and / or current fluctuations of the transmitter coil 103 and demodulate the load modulation based thereon. Those skilled in the art know, for example, the principle of load modulation as used in the Qi wireless power transmission system, and thus, these will not be described in further detail herein.

[0067] The first communication device 207 may be further arranged to transmit data to the power receiver, for example, by specifically modulating the drive signal and thus the power transmission signal using frequency, amplitude and / or phase modulation.

[0068] It will be understood that other approaches for communicating data between the power transmitter 101 and the power receiver 105 may be used in other embodiments. For example, in some embodiments, the communication may be carried out using a separate communication coil or using a separate communication channel that can actually be achieved using the transmitter coil 103. For example, in some embodiments, Near Field Communication may be implemented, or a high-frequency carrier (for example, having a carrier frequency of 13.56 MHz) may be superimposed on the power transmission signal.

[0069] FIG. 5 shows some exemplary elements of the power receiver 105. The receiver coil 107 is coupled to a power receiver controller 501 that couples the receiver coil 107 to the load 503. In many embodiments, the receiver coil 107 is part of a power receiver input circuit that also includes a capacitor for forming a resonant circuit with the receiver coil 107. The power receiver controller 501 includes a power control path that converts the power extracted by the receiver coil 107 into a power source suitable for the load. Further, the power receiver controller 501 can include various power receiver controller functions required to perform power transmission, particularly functions required to perform power transmission in accordance with the Qi standard.

[0070] The power receiver 105 further includes a second communicator 505 configured to receive data transmitted from the power transmitter 101. In an example, the second communicator 505 is configured to appropriately demodulate the amplitude, frequency, and / or phase modulation of the power transmission signal to obtain data transmitted from the power transmitter.

[0071] The second communicator 505 is further configured to transmit data to the power transmitter by changing the load of the receiver coil 107 in accordance with the data to be transmitted to the power transmitter 101. Then, as is known to those skilled in the art, the load variation is detected and demodulated by the power transmitter 101.

[0072] As described above, in other embodiments, other communication methods can be used, such as using a separate dedicated short-range communication approach such as NFC.

[0073] The power transmitter and the power receiver further include functions for implementing a power control loop for dynamically adapting the power level of the power transmission signal during the power transmission phase. The power receiver can continuously monitor the received power level and compare it with a desired power level. Then, a power control error message can be transmitted, and the power transmitter can increase or decrease the power level by changing the characteristics of the drive signal.

[0074] In particular, the power transmitter is configured with a power loop controller 209 that controls the power level of the power transmission signal by adjusting the parameters / characteristics of the drive signal. The power loop controller 209 can adjust parameters such as the current, voltage, frequency, duty cycle, active duration (burst mode) of the drive signal, and as a result, the power level of the power transmission signal is changed.

[0075] The power loop controller 209 can be implemented as an integrated circuit, such as an application specific integrated circuit (ASIC) for example. In some embodiments, the power loop controller 209 is firmware executed on a suitable processor such as, for example, a central processing unit, a digital signal processing unit, or a microcontroller, or can be implemented as a programmed processing unit such as software. In such embodiments, it will be understood that the processing unit may include on-board or external memory, a clock drive circuit, an interface circuit, a user interface circuit, etc. Such circuits may also be implemented as part of the processing unit, as an integrated circuit and / or as discrete electronic circuits.

[0076] In some embodiments, the power loop controller 209 may be implemented partially or fully as discrete electronic circuits. In different embodiments, the power loop controller can be implemented as an analog electronic circuit, a digital electronic circuit, or a mixed analog circuit.

[0077] In different embodiments, it will be understood that different parameters can be used to represent the power level of the power transmission signal. For example, in many embodiments, the power level of the power transmission signal can be represented by characteristics or parameters of the transmitter coil signal, such as specifically the current, voltage, frequency, duty cycle and / or power of the signal of the transmitter coil 103. In many embodiments, the power level of the power transmission signal can be provided and represented by the coil current for the transmitter coil 103. In many embodiments, the power control loop can control the power level of the power transmission signal by specifically controlling the level of the coil current through the transmitter coil 103.

[0078] In some embodiments, the power level of the power transmission signal can be represented by characteristics or parameters of the drive signal, such as specifically the current, voltage, frequency, duty cycle, active duration and / or power of the drive signal.

[0079] For example, increasing the current or duty cycle of the drive signal directly affects the signal of the transmitter coil 103 and thus the generated power transmission signal, thereby increasing the power level of the power transmission signal.

[0080] In fact, the power level of the power transmission signal can depend on several parameters, and in various embodiments, any such parameter can be used to represent and / or control the power level of the power transmission signal. It will also be understood that different parameters may be used to represent the power level of the power transmission signal. For example, the power receiver and the power transmitter may use different parameters to represent the power level of the power transmission signal (for example, the power transmitter may use the current of the transmitter coil 103, and the power receiver may use the extracted power level). In such embodiments, for example, conversions between different parameters and representations may be used, or data related to one parameter may be adapted by making relative changes to another parameter.

[0081] Also, it will be understood that the parameters controlled and adapted by the power control loop may be modified directly or may be modified indirectly by changing another parameter. For example, the power control loop can control the coil current for the transmitter coil 103, but can do so by changing, for example, the frequency of the drive signal in order to vary the coil current to a desired value.

[0082] FIG. 6 is a diagram showing an example of a functional aspect of an exemplary power control loop that can be employed in the system of FIG. 1.

[0083] The loop specifically controls the coil current I txc i.e., the coil current can be considered as the loop output or loop variable. The coil current I txc corresponds to the power level of the power transmission signal. Specifically, the magnetic flux and magnetic field strength generated by the transmitter coil 103 are directly given by the coil current, and thus the signal induced in the receiver coil 107 is directly given by the transmitter coil current.

[0084] Thus, the loop includes the power path from the transmitter coil current to the power level extracted by the power receiver 105. This path includes the generation of the electromagnetic flux of the power transmission signal, the induction of the signal in the power receiver coil, the power receiver power path, etc. The extracted power (e.g., supplied to the load 503) is compared by the power receiver 105 with a desired (current) reference power level PWR REF. Based on the comparison power control error indicator, an ERR is generated and transmitted to the power transmitter 101 in the power control error message.

[0085] The power transmitter 101 has a function of adapting the coil current I txc according to the power control error indicator. The power level of the power transmission signal, in a specific example, the coil current I txcThe changes are relative, and thus the control loop can increase or decrease the power level from the current level in response to the power control error metric / message. The relative change in power level / coil current corresponds to including an integration function 603 within the power control loop.

[0086] Furthermore, the power loop controller 209 and the power transmitter implement a specific power change circuit 605 for changing the power level in response to the power control error metric. For example, the power control error message can request to increase the power level by a given relative amount, e.g., 2%. In response, the power change circuit 605 can determine that the coil current I txc should be increased by 2% and proceed to implement this change.

[0087] In many embodiments, the power level can be adapted by changing the characteristics / parameters of the drive signal. Thus, the power change circuit 605 can include circuitry for changing the parameters of the drive signal, and as a result, this causes the desired change in the power level, particularly the coil current I txc to occur.

[0088] Specifically, in many embodiments, the output circuit of the power transmitter and the input circuit of the power receiver include resonant circuits, and the power level of the power transmission signal and the coil current I txc is controlled by changing the drive frequency of the drive signal closer to or away from the resonant frequency. In this way, by changing the frequency closer to the resonant frequency, an increase in the coil current I txc can be achieved.

[0089] Alternatively or additionally, other parameters of the drive signal that can be modified include the current, voltage, power, duty cycle, or duration of the drive signal. Increasing any of these increases the power level of the power transmission signal, and decreasing any of these decreases the power level.

[0090] In some embodiments, the power change circuit 605 can include a direct correspondence between the drive signal parameters and the power transmission signal level (including the coil current I txc ). For example, if a request to increase the power level by 2% is received, the power change circuit 605 can directly change the drive signal frequency or current by a certain amount. Such a direct correspondence can be based on, for example, a look-up table generated during the manufacturing or calibration process.

[0091] In many embodiments, the power change circuit 605 may include an internal loop that controls the drive signal parameters to bring about a desired change in the power level of the power transmission signal. For example, in response to a received error power control message, an internal circuit that changes the reference value for, for example, the coil current I txc may be implemented. And the internal loop can adjust the drive signal frequency, for example, until the actual coil current I txc equals the desired new value.

[0092] Also, it will be understood that in many embodiments, the power level may be the effective power level or the active power level. However, in other embodiments, the power level under consideration may be the complex power level, the reactive power level, or the apparent power level.

[0093] The power control loop provides a very effective and reliable approach for the power receiver to control the power transmission operation. For example, it enables the power receiver to continuously adapt the transmitted power level, for example, to maintain a desired speed for a load in the form of a motor.

[0094] The system of FIG. 1 further includes additional features for controlling the operation of the power control loop in specific situations, thereby providing improved operation in many scenarios.

[0095] Specifically, in the system, the power receiver can have a plurality of power level modes related to power transmission. Specifically, the power receiver can be associated with a set of power level modes / a plurality of power level modes where each power level mode is linked to a reference power level for the power transmission signal. The power receiver can be configured to operate in different discrete modes, each of these modes having a given power level requirement from the power transmission signal. For example, a power receiver in the form of a blender can have, for example, five different motor speed settings and thus can be associated with five different operating modes where each of these extracts a different amount of power from the power transmission signal.

[0096] The power transmitter 101 includes a mode circuit 211 coupled to a power loop controller 209 and a mode storage device 213. The mode storage device 213 may be configured to store data for different power level modes. Specifically, the mode storage device 213 is configured to store a set of power level modes for the power receiver where each power level mode is associated with a reference power level for the power transmission signal.

[0097] The mode circuit 211 can be implemented as an integrated circuit, such as an application specific integrated circuit (ASIC) for example. In some embodiments, the mode circuit 211 can be implemented as a programmed processing unit, such as firmware or software executed on a suitable processor, such as a central processing unit, a digital signal processing unit or a microcontroller for example. In such embodiments, it will be understood that the processing unit may include on - board or external memory, a clock drive circuit, an interface circuit, a user interface circuit, etc. Such circuits may also be implemented as an integrated circuit and / or as discrete electronic circuits as part of the processing unit.

[0098] In some embodiments, the mode circuit 211 may be implemented, in part or in whole, as a discrete electronic circuit. In different embodiments, the power loop controller can be implemented as an analog electronic circuit, a digital electronic circuit, or a hybrid analog circuit.

[0099] The power level mode can be represented by different parameters in different embodiments, and any suitable parameter that can indicate the power level can be used. For example, the reference power level can be represented by a value indicating the actual load provided to the load 503 by the power receiver. In other embodiments, the reference power level may be indicated by the nominal power extracted from the power receiver for nominal operating conditions such as, for example, when no object is present and the power transmitter and the power receiver have their nominal positions relative to each other. In still other embodiments, the reference power level may be represented by the value of a loop variable controlled by, for example, a reference coil current value for a given mode. In still other embodiments, the reference power level can be represented by the value of a parameter of the power transmitter that is controlled to provide the desired power level. In many embodiments, the reference power level can be represented by the value of a characteristic of the drive signal such as the current, voltage, frequency, duty cycle, active duration (burst mode) of the drive signal. All of these parameters can reflect the power level in various embodiments, and changes in the values of such parameters can affect the power level of the power transmission signal. Also, it will be understood that in some embodiments, a combination of parameters (e.g., using different parameters for different power level modes) may be used.

[0100] In the system, the power receiver can operate in a separate set of power level modes, and the mode storage device can store the reference power level for each mode.

[0101] In the system, the power receiver may switch to different modes, and in this regard, a message may be sent to the power transmitter to notify it of the mode change. Specifically, the power receiver can send a mode request message that can indicate the power level mode to which the power receiver is switching (or desires to switch). It will be understood that any form of indicator may be used. For example, the power level mode may be associated with individual IDs, and the mode request message may include the ID of the power level mode that the power receiver desires to switch to.

[0102] When the receiver 207 receives a mode request message, it transfers the ID to the mode circuit 211, and the mode circuit 211 accesses the mode storage device 213 to obtain the reference power level of the power level mode specified by the ID. The mode circuit 211 is configured to adapt the drive signal so as to set the power level of the power transmission signal to this reference value, that is, the drive signal can be adapted so that a power transmission signal having a value corresponding to the obtained reference value is obtained as a result.

[0103] The reference value can be represented by any suitable value, specifically, in particular, the coil current I txc It will be understood that it can be represented by any value or parameter that affects the power level of the power transmission signal, such as etc. The value can be adapted directly or indirectly, for example, by adapting the current, voltage, frequency, duty cycle, active duration (burst mode) of the drive signal. In fact, in some embodiments, the values of these parameters may themselves be considered reference values set by the mode circuit 211 that affect the power level of the power transmission signal.

[0104] The first reference value depends on the reference power level for the indicated power level mode. Thus, upon receiving a mode request message, the mode circuit 211 can obtain the reference power level for the power level mode indicated in the mode request message. Then, from this reference power level, a reference value for a given parameter related to the power level of the power transmission signal can be determined (the power level of the power transmission signal depends on the value of the parameter for which the first reference value is determined). The first reference value may be determined, in particular, for a loop parameter, which is a parameter representing a signal value at a certain point within the loop. And the mode circuit 211 can set the parameter of the drive signal such that the parameter becomes the first reference value.

[0105] In many embodiments, this can be done directly. For example, in many embodiments, the reference value may be determined directly for parameters of the drive signal such as the current, voltage, frequency, duty cycle, active duration (burst mode), etc. of the drive signal. And the mode circuit 211 may proceed to directly set the drive signal to the reference value. For example, the power receiver can transition to a specific power level mode and transmit a mode request message indicating this mode. The mode circuit 211 can directly determine that for this mode, a reference power level corresponding to a given value of the drive signal frequency is stored, and can immediately change the drive signal frequency to this value without considering the current value (or any other value) of the frequency. For example, assuming that the power transmission resonant circuit is tuned to 100 kHz, for example, a mode request message indicating mode 1 can cause the mode circuit 211 to set the drive signal frequency to 150 kHz, a mode request message indicating mode 2 can cause the mode circuit 211 to set the drive signal frequency to 160 kHz, and a mode request message indicating mode 3 can cause the mode circuit 211 to set the drive signal frequency to 170 kHz.

[0106] In some embodiments, the reference value may be determined for a parameter that is not the parameter of the drive signal itself. For example, specifically, it may be a parameter of the transmitter coil signal such as coil current I txc . In such a case, the mode circuit 211 can adapt the parameter of the drive signal to result in a desired parameter value for the transmitter coil signal. This can be achieved by the mode circuit 211 in some embodiments using a direct relationship or function between the adapted characteristic of the drive signal and the parameter of the transmitter coil signal, such as a direct relationship between the frequency of the drive signal and coil current I txc . This relationship can be stored, for example, in a look-up table. However, in many embodiments, it is difficult to determine such a relationship, and the power transmitter can implement, for example, a high-speed internal loop. For example, coil current I txc can be measured and compared with a desired first reference value, and the frequency of the drive signal can be quickly changed / adapted to result in a desired value of coil current I txc .

[0107] In many embodiments, the stored reference power level may be directly represented by the first reference value, that is, the mode circuit 211 may directly obtain the reference power level of the required power level mode and use this as the reference value, that is, directly set the reference parameter to this value. For example, in many embodiments, the mode storage device 213 can directly store the frequency for each of the power level modes, and when a mode request message is received, directly extract the stored frequency value and set the drive signal to this frequency. In other embodiments, some conversions may be required, which can be achieved, for example, using a look-up table in which data can be registered during a calibration phase.

[0108] In an embodiment, the mode memory device can store a plurality of parameters for each power level mode, such as both the parameters of the drive signal and the extracted power value. Thus, in such a case, the reference power level can include a plurality of components, or equivalently, the mode memory device can store a plurality of reference power levels for each power level mode. In such an embodiment, the mode circuit 211 can use an appropriate parameter value or a plurality of parameter values. For example, when a mode request message indicates that the power receiver switches to a power level mode that extracts, for example, 500 W, the mode circuit 211 can identify the power level mode corresponding to the extracted power of 500 W and retrieve the drive frequency stored for this power level mode.

[0109] This approach can provide a system that can adapt very quickly to different operating modes. The mode request message can be transmitted during the power transmission phase, and thus can provide a means for quickly changing the power transmission operating point. Typically, power adaptation is achieved using power loop control, which is adapted to provide efficient operation but is typically relatively slow to provide reliable performance. The described operation provides a means to override the power control loop, specifically, the power control loop can be dynamically changed / re-initialized to a new operating point that matches a new power level mode during the power transmission phase.

[0110] Thus, the mode circuit 211 can be configured to adapt the drive signal by changing the power control loop variable in response to the reception of a mode request message.

[0111] The mode circuit 211 is configured to set the power level of the power transmission signal to a first reference value in response to receiving a mode request message. The power level of the power transmission signal is a state variable of the power control loop. Thus, the mode circuit 211 is configured to set the state variable of the power control loop to a reference value in response to receiving a mode request message, and the reference value depends on the mode request message, specifically on the power level mode indicated in the mode request message.

[0112] The adaptation of the signal can be independent of the operation of the power control loop. Thus, in response to a mode request message, this approach can override the operation of the power control loop and re-initialize the operation for the new power level mode.

[0113] In some embodiments, the mode circuit 211 can be configured to change the power control loop state variable to adapt the drive signal to set the power level of the power transmission signal to a first reference value in response to receiving a mode request message, and the first reference value corresponds to the reference power level of the first power level mode among the plurality of power level modes indicated in the mode request message.

[0114] In some embodiments, the mode circuit 211 may be configured to adapt the drive signal to set the power level of the power transmission signal to a first reference value in response to receiving a mode request message, the first reference value corresponding to the reference power level of the first power level mode among the plurality of power level modes indicated in the mode request message, and the adaptation includes changing the state variable of the power control loop.

[0115] In some embodiments, the mode circuit 211 may be configured to adapt the drive signal by changing the state variable of the power control loop to set the power level of the power transmission signal to a first reference value in response to receiving a mode request message, and the first reference value corresponds to the reference power level of the first power level mode among the plurality of power level modes indicated in the mode request message.

[0116] In some embodiments, the mode circuit 211 may be configured to adapt the drive signal by changing the state variable of the power control loop so as to set the power level of the power transmission signal to a first reference value in response to receiving a mode request message, where the first reference value corresponds to the reference power level of a first power level mode among a plurality of power level modes indicated by the mode request message.

[0117] The mode circuit 211 may be configured to overwrite or replace the current value of the loop state variable with a reference value that depends on the power level mode indicated in the mode request message.

[0118] The adaptation of the drive signal / setting of the power level of the power transmission signal / changing of the power level of the power transmission signal can be faster than what can be achieved by the power control loop. The time constant / period for adapting / setting the power level of the power transmission signal to the reference value in response to the mode request message can be shorter than the time constant / period of the power control loop. In some embodiments, the setting of the power level may be a step change.

[0119] In many embodiments, the time constant of the power control loop is 250 msec or more, 500 msec or more, or 1 second or more, while the setting of the power level in response to the mode request message can be in a lower period, specifically less than 100 msec, less than 250 msec, or less than 500 msec respectively.

[0120] In many embodiments, the period for adapting the drive signal to set the power level is less than the time constant of the power control loop, and in many embodiments it may be less than 50% or less than 25% of this time constant. This period may be the delay from when the mode request message is received until the power level of the power transmission signal is set to the first reference value (specifically, until it reaches the first reference value). The time constant of the control loop reflects the speed at which the loop responds to changes. The time constant may be the period until the loop variable (specifically, such as the power level of the power transmission signal) reaches 63.2% of its final (steady-state) value following a step change.

[0121] As will be described in more detail below, it will be understood that different approaches can be used for the power transmitter to determine and store the power level mode and related reference levels.

[0122] In some embodiments, the power level mode and reference power level may be stored for a plurality of power receivers. Thus, the mode storage device 213 may be configured to store a set of power level modes for different power receivers.

[0123] When initializing the power transmission operation (or actually at any suitable time), the power receiver can transmit an indicator of the power receiver. Then, the mode circuit 211 / mode storage device 213 can proceed to retrieve the set of power level modes that match a particular ID.

[0124] In some embodiments, the ID may be a unique device ID. This can be very useful, for example, in embodiments where the stored power level mode and reference power level are determined by individual initialization using individual devices. For example, when a new power receiver is detected, the power transmitter can start an initialization routine to determine the power level mode and reference power level. The next time the power receiver is detected, the power transmitter can proceed to use the already stored values without executing the initialization process. The power transmitter can then gradually accumulate data for the appropriate power receivers, enabling the use of functions for various power receivers with less overhead.

[0125] Alternatively or additionally, the ID may be a type ID indicating, for example, the model, manufacturer, etc. of the power receiver. The power transmitter can store, for example, power level mode data for different types of various devices and, upon receiving the type ID, can select the power level mode data that matches the received ID.

[0126] In some embodiments, the power level mode and reference power level data may be based on an initialization phase executed by the power transmitter and the power receiver.

[0127] For example, in some embodiments, the initialization of a new power transmission (for example, only for power receivers for which power level mode data is not stored) can include first executing a process to determine the reference values to be used during operation. During this initialization phase, the power receiver goes through different power level modes, and for each power level mode, the mode circuit 211 can determine a value representing the power level and store this as the reference power level for that mode.

[0128] For example, in order for the power receiver to pass through power level modes step by step, for example, a predetermined timing can be applied so that it operates in each mode for 10 seconds before switching to the next mode. Alternatively, the power receiver can send a message when switching to the next mode, or the power transmitter can send a message requesting that the next mode be applied.

[0129] For each power level mode, the power transmitter can operate a power control loop to reach a stable state. When the stable state is reached, the power transmitter can measure a desired parameter used to represent the power transmission signal power level, such as the coil current I txc or a value such as the drive signal frequency. And this value can be stored as the reference power level for that mode.

[0130] And the power receiver can switch to the next power level mode, for example, at the request of the power transmitter, and this process can be repeated.

[0131] This approach can typically be implemented by the power receiver passing through power level modes step by step, typically from lower power levels to higher power levels. This can, for example, reduce the risk of an undesirable overvoltage condition.

[0132] The initialization process can typically be performed as part of power transmission initialization and can thus be executed before the power transmission phase.

[0133] As a specific example, in an air fryer, which is a kitchen appliance that uses a convection mechanism to circulate hot air around food for cooking, the heating element may be turned on / off. This usually results in a very large load step, such as 50 - 1200W, which will be repeated during the operation of the device to keep the temperature constant. Figure 7 shows a schematic diagram showing the power step PWR and the resulting temperature change TEMP.

[0134] In this example, after the device is turned on and power transmission proceeds while the power is controlled by the power control loop, the operating point is saved (SVE 1 and 2). The operating point reflects the power transmission level of the power transmission signal with respect to the current power level mode of the air fryer and can be represented by any suitable parameter value as described above.

[0135] Values are stored for both the high power level mode and the low power level mode, thereby enabling the mode storage device 213 to provide reference power levels for two different power level modes. And when changing the power level mode, the power receiver can send a mode request message MRQ, thereby enabling the power transmitter to directly jump to a new operating point (nearby) by overriding the power control loop using the stored values.

[0136] Therefore, when a change in the power level mode is about to occur, the power receiver can notify that a load change is occurring and which mode to transition to. And the system, specifically the power transmitter, will then know which operating point it should jump to. This reduces the risk that the transmitted power will be too high or too low, for example due to delays in the control loop. This helps prevent damage to the device and reduces the risk of power loss in power reception even in extreme situations.

[0137] Furthermore, the stored data can be retrieved during power transmission operations with different stored values and thus can be used for future power transmission between the power receiver and the power transmitter. The mode storage device 213 can, in particular, store values for a plurality of power receivers and, when a power receiver is detected for power transmission, can proceed to use the set stored for this power receiver. If a new power receiver is detected or the stored data is considered invalid, for example, because it is too old, the power transmitter and the power receiver can proceed to generate and store new / updated data for the power receiver.

[0138] Therefore, if a combination of a power transmitter / power receiver device and a specific power mode is used in the future, the actually used operating points can be reused. The operating values are determined during startup or initialization as the system passes through all power level modes step by step, and the resulting operating points and reference power levels are represented by any suitable parameters, and the values are stored as the reference power levels.

[0139] For example, in the case of an air fryer, the heating element may be turned on or off, but the fan always remains on. During startup of the device, only the fan is first turned on, and its operating point is measured and saved (SVE 1). Then the heating element is turned on, and the associated operating point is measured and stored (SVE 2). Next, during operation, when the heating element is to be turned on / off, the power receiver can notify that a load change is about to occur, and a mode request message MRQ for different power modes is generated and sent to the power transmitter. Next, the power transmitter can immediately enter the correct operating point without the delay of the control loop. The power receiver may be notified that the power transmitter has switched to the correct power mode by receiving a handshake in the form of a command.

[0140] In some embodiments, the power transmitter can further include a detection circuit 215 configured to detect a power transmission abnormality in response to a comparison between the current power level of the drive signal and a reference power level for the current power level mode among a set of power level modes.

[0141] When operating in a particular power level mode, the power control loop can vary the power level of the power transmission signal in response to an error control message from the power receiver. However, these variations are expected to be relatively small. For example, when the air fryer is operating in a 1200W load mode, the exact power drawn may vary, and the power receiver can control this so that the exact desired power for the current situation is drawn. However, although the power level may vary accordingly, it is expected that the variation is limited under normal operating conditions. For example, during normal operation, the power is expected to be in the range of 1100W to 1300W.

[0142] Accordingly, the detection circuit 215 can compare the current power level with a stored reference power level for the power level mode in which the system is currently operating. For example, the detection circuit 215 can compare the currently measured coil current I txc with the stored coil current for the state in which the device is operating.

[0143] If the comparison indicates that the current power level is too different from the reference power level, for example, if the measured coil current is significantly different from the stored reference coil current value by more than a threshold, the detection circuit 215 can determine that the current operating point is not what should be experienced during normal operation, and thus can identify that an abnormality has been detected.

[0144] In such a case, the detection circuit 215 can, for example, notify the transmitter controller 205 that an abnormality has been detected. In response, the transmitter controller 205 can proceed to change the parameters of the power transmission. For example, it can be configured to limit the power level to less than a given value, and for example, the maximum coil current I txc can be set to a level low enough to ensure that no damage occurs. In some embodiments, the maximum power level may be set to zero, and specifically, when an abnormality is detected, the power transmission may be terminated.

[0145] It will be understood that the exact criteria used to detect an abnormality based on the comparison depend on the preferences and requirements of the individual embodiments, and that many different approaches and criteria are possible. It will also be understood that the evaluation can include other considerations, for example, it can include conversions between different parameters. For example, if the reference power level is stored as a coil current value, but the current power level is set / measured based on the drive signal frequency, the comparison can include a conversion between the coil current and the drive signal frequency.

[0146] It will also be understood that the actions taken in response to the detection of an abnormality depend on the preferences and requirements of the individual embodiments. For example, in some embodiments, the power transmission may be restricted or terminated. In other embodiments, the detection of an abnormality can simply result in the generation of a user warning, such as, for example, switching on a warning light. In yet other embodiments, a message can be sent to the receiver, and the receiver can perform an action in response, for example, it can change the power supply to the load.

[0147] In some embodiments, the mode request message includes a timing indicator, and the mode circuit is configured to adapt the timing for setting the level of the drive signal in accordance with this timing indicator.

[0148] Specifically, the mode request message can include an indication of when the power receiver is attempting to switch to a new power level mode. For example, the mode request message can indicate that the power receiver is attempting to instantaneously switch to a new power level mode, in which case the power transmitter can immediately switch to the new mode by setting the power level of the power transmission signal to a corresponding reference value, for example, by setting the coil current to a stored reference value of the coil current for the new power level mode.

[0149] In other situations, the power receiver can send a mode request message indicating that the change in power level mode will occur at a future point in time, for example, 5 seconds later. In this case, the power transmitter can delay the setting of the power level for the indicated time, that is, delay the setting of the power level for overriding the loop for 5 seconds.

[0150] In some embodiments, the timing indicator can indicate multiple power level mode changes. For example, the mode request message can indicate that the power receiver switches between two different modes (e.g., two power level modes of an air fryer) at a given interval (e.g., every 20 seconds), and the power transmitter can proceed to determine the timing of the direct setting of the power level to correspond to these switches.

[0151] It will be appreciated that in some embodiments, the power transmitter can send a confirmation message to the power receiver that the power level has been set, or will be set, and the power receiver can wait for such a confirmation message before switching between power level modes.

[0152] In some embodiments, the power transmitter may be configured to determine a reference power level based on data received from the power receiver.

[0153] In this example, the mode circuit 211 can receive from the power receiver information that enables the calculation of a reference power level. In particular, the power receiver can provide a receiver setting message comprising power receiver setting parameters. The mode circuit 211 can determine a reference power level for at least one power level mode of a set of power level modes based on the power receiver setting characteristics.

[0154] The power receiver setting parameters can specifically comprise at least one of the following: a power receiver ID; a power receiver type ID; power receiver coil characteristics; power receiver coil dimension characteristics; and power receiver coil inductance characteristics.

[0155] The power receiver ID or type ID can enable the power transmitter to obtain data that describes the characteristics of this power receiver. This data can, for example, directly provide the power level modes and reference power levels for a specific receiver as described above. However, typically, it includes the characteristics of the power receiver that indicate the power processing of the power receiver. For example, the ID or type ID may enable the power transmitter to obtain setting data that describes the characteristics of the power receiver coil (e.g., dimensions or inductance). Thus, the power receiver coil characteristics may be transmitted directly by the power receiver or may be provided indirectly by identifying the power receiver to enable the power transmitter to obtain the relevant data. This data may, in some embodiments, be obtained from an internal storage device or, in many embodiments, from an external server. For example, each manufacturer may provide a database accessible from a suitably equipped power transmitter (e.g., via the Internet).

[0156] In some embodiments, the configuration data received from the power receiver can be used to calculate values suitable for setting the parameters of the drive signal or the transmitter coil signal when a power level mode change occurs. For example, it can be used to calculate the drive signal frequency, duty cycle, or coil current for different power level modes. The power level mode can be represented, for example, by a load power value indicating the power supplied to the load 503 by the power receiver, and the corresponding values of the power level parameters adapted by the mode circuit 211 can be calculated using the data received from the power receiver. For example, this data may be used to calculate the coil current required to supply the indicated power to the load 503.

[0157] This data can be used, for example, to determine the power path from the parameters set in the power transmitter to the load of the power receiver. FIG. 8 shows an example of a model regarding the power path from the voltage of the driver 201 to the load 503.

[0158] In this example, the following reference numerals are used: Vin: the voltage of the drive signal from the driver 201. Rp: the internal resistance of the driver and the loss in the output circuit. Cp: the capacitor 203 of the power transmitter resonant output circuit. Lp: the transmitter coil 103 Ls: the receiver coil 107 Cs: the capacitor of the power receiver input resonant circuit Rl: the load 503

[0159] One of the main parameters for power transmission in a wireless power transmission system is the coupling coefficient between the power transmitter coil and the power receiver coil. This depends on a plurality of factors including the receiver coil characteristics. Therefore, the coupling coefficient between the power transmitter coil and the power receiver coil can be determined using the power receiver configuration data. The mode circuit 211 can determine one or more reference power levels for at least one power level mode based on the coupling coefficient.

[0160] For example, the power transmitter can store a reference power receiver and a plurality of reference power levels corresponding to the nominal power level mode. However, for each of the power level modes, different reference power levels may be stored due to different coupling coefficients, which are important values in determining the power transmitter parameters related to the extracted power level. Then, using the received information, the coupling coefficient for the current power receiver can be calculated, and the power transmitter can accordingly obtain the reference power level that matches the current coupling coefficient.

[0161] In some embodiments, the mode circuit 211 can be configured to determine the power transfer function between the relevant parameters of the drive signal or the transmitter coil signal and the output power from the power receiver to the load. Thus, the power transfer function can reflect the relationship between the parameters set by the mode circuit 211 and the resulting power receiver output power. Next, this power transfer function can be used to directly calculate the reference value of the desired parameters from the load power from the power receiver.

[0162] The power transmission function is thus calculated from the power receiver setting data transmitted from the power receiver, and the determination of the power transmission function may specifically include the determination of the coupling coefficient between the power transmitter coil and the power receiver coil.

[0163] More specifically, the power receiver setting data can be used to fill in the unknown values Cs, Ls, Rs, and Rl in FIG. 8. The power transmitter setting data can be used to fill in Rp, Cp, and Lp. The coupling coefficient determines the shared magnetic flux path between Ls and Lp. This can be estimated / calculated using the dimensions of the coil set-up. With the coil diameter and the distance between the two, simulations / measurements can be performed to see the effect on the coupling coefficient. And a function / lookup table can be created to output the coupling coefficient for a specific coil dimension and arrangement. The coupling coefficient can also be measured by disconnecting the load on one side and supplying voltage / current to the other side. Since the load is disconnected, power is not transmitted, but there is voltage, which indicates the magnitude of the mutual inductance relative to the self-inductance. In all models, Kirchhoff's laws can be used to derive the transfer function from the input voltage to the output current / voltage. Based on these values, the power supplied to the load can be determined (conversely, the drive signal parameters for a specific load can also be determined).

[0164] It will be understood that the foregoing description for clarity 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, functions shown to be performed by separate processors or controllers may be performed by the same processor or controller. Accordingly, references to specific functional units or circuits should be seen only as references to suitable means for providing the described functionality, and not as indicating any strict logical or physical structure or organization.

[0165] The present invention can be implemented in any suitable form including hardware, software, firmware, or any combination thereof. Optionally, the present invention can be at least partially implemented as computer software executed on one or more data processors and / or digital signal processors. The elements and components of the embodiments of the present invention can be physically, functionally, and logically implemented in any suitable manner. In fact, the functions 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 among 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 forms set forth herein. Rather, the scope of the present invention is limited only by the appended claims. Further, although a certain feature may appear to be described in connection with a particular embodiment, those skilled in the art will recognize that various features described in the described embodiments may be combined in accordance with the present invention. In the claims, the term "comprise" does not exclude the presence of other elements or steps.

[0167] Furthermore, although listed individually, a plurality of means, elements, circuits or method steps may be implemented by, for example, a single circuit, unit or processor. Moreover, although individual features may be included in different claims, these may optionally be advantageously combined, and inclusion in different claims does not mean that combinations of the features are not feasible and / or not advantageous. Also, including a feature in one category of claims does not mean a limitation to this category, but rather indicates that the feature is equally applicable, if necessary, to other claim categories as well. Further, the order of features in the claims does not mean a specific order in which the features must operate, and in particular, the order of individual steps in method claims does not mean that the steps must be performed in this order. Rather, the steps can be performed in any suitable order. Additionally, reference to the singular does not exclude the plural. Thus, references such as "a", "an", "first", "second", etc. also do not exclude the plural. A parameter or value corresponding to another parameter or value may indicate that one parameter / value is considered / expected to reduce to the other parameter / value, specifically meaning that the parameter / value corresponding to the power level is a parameter / value that is considered / expected to reduce to the power level. The reference signs in the claims are provided merely as illustrative examples and should not be construed as limiting the scope of the claims in any way.

Claims

1. A power transmitter for wirelessly supplying power to a power receiver via an electromagnetic power transmission signal, a receiver for receiving a message from the power receiver, the output circuit having a transmitter coil for generating the power transmission signal in response to a drive signal applied to the output circuit, a drive circuit for generating the drive signal, a power loop controller implementing a power control loop for controlling the drive signal to adjust the power level of the power transmission signal, the power control loop being configured to apply a change to the power level of the power transmission signal in response to a power control error message received from the power receiver, a power loop controller, a mode storage device configured to store a plurality of power level modes for the power receiver, each power level mode being associated with a reference power level for the power transmission signal, a mode storage device, a mode circuit configured to adapt the drive signal to set the power level of the power transmission signal to a first reference value in response to the reception of a mode request message, the first reference value corresponding to the reference power level of a first power level mode indicated in the mode request message among the plurality of power level modes, a mode circuit, having, the mode circuit being configured to determine, for at least one parameter value of the drive signal and the power transmission signal, the reference power levels for at least some of the plurality of power level modes during an initialization phase in which the power receiver passes through the at least some of the power level modes step by step, the mode storage device being configured to store the reference power levels for the at least some of the power level modes, a power transmitter.

2. The power transmitter according to claim 1, further comprising a detection circuit for detecting a power transmission abnormality in response to a comparison between the current power level of the power transmission signal and the reference power level of the current power level mode among the plurality of power level modes.

3. The power transmitter according to claim 1 or 2, wherein a period for adapting the drive signal to set the power level of the power transmission signal to the first reference value is less than the time constant of the power control loop.

4. The mode storage device is configured to store a plurality of parameters for at least one power level mode, the plurality of parameters including at least one reference power level representing the power level of the power transmission signal, and at least one parameter value for at least one of the drive signal and the signal of the transmitter coil, the at least one parameter value being at least one value of the drive signal and the signal of the transmitter coil with respect to the power level of the power transmission signal indicated by the reference power level. The power transmitter according to claim 1.

5. The power transmitter according to claim 1, wherein the initialization phase is before the power transmission phase.

6. A power transmitter for wirelessly supplying power to a power receiver via an electromagnetic power transmission signal, a receiver for receiving a message from the power receiver; an output circuit having a transmitter coil for generating the power transmission signal in response to a drive signal applied to the output circuit; a drive circuit for generating the drive signal; a power loop controller implementing a power control loop for controlling the drive signal to adjust the power level of the power transmission signal, the power control loop being configured to apply a change to the power level of the power transmission signal in response to a power control error message received from the power receiver. A power loop controller; a mode storage device configured to store a plurality of power level modes for the power receiver, each power level mode being associated with a reference power level for the power transmission signal; a mode circuit configured to adapt the drive signal to set the power level of the power transmission signal to a first reference value in response to the reception of a mode request message, the first reference value corresponding to the reference power level of a first power level mode indicated in the mode request message among the plurality of power level modes. A mode circuit; having The receiver is configured to receive a power receiver setting message from the power receiver, the power receiver setting message having power receiver setting parameters, and the mode circuit is configured to determine the reference power level for at least one of the plurality of power level modes according to the power receiver setting parameters. The mode circuit is configured to determine a coupling coefficient between the transmitter coil and the power receiver coil of the power receiver based on the power receiver setting parameters, and to determine the reference power level for the at least one power level mode based on the coupling coefficient. A power transmitter. **Claim 7** The power receiver setting parameters are a power receiver ID, a power receiver type ID, power receiver coil characteristics, power receiver coil dimension characteristics, power receiver coil inductance characteristics, The power transmitter according to claim 6, having at least one of them. **Claim 8** A power transmitter for wirelessly supplying power to a power receiver via an electromagnetic power transmission signal, a receiver for receiving a message from the power receiver; an output circuit having a transmitter coil for generating the power transmission signal in response to a drive signal applied to the output circuit; a drive circuit for generating the drive signal; a power loop controller implementing a power control loop for controlling the drive signal to adjust the power level of the power transmission signal, the power control loop being configured to apply a change to the power level of the power transmission signal in response to a power control error message received from the power receiver. A power loop controller; a mode storage device configured to store a plurality of power level modes for the power receiver, each power level mode being associated with a reference power level for the power transmission signal; a mode circuit configured to adapt the drive signal to set the power level of the power transmission signal to a first reference value in response to the reception of a mode request message, the first reference value being a reference power level of a first power level mode indicated in the mode request message among the plurality of power level modes. corresponding mode circuit; having The receiver is configured to receive a power receiver setting message from the power receiver, the power receiver setting message having power receiver setting parameters, and the mode circuit is configured to determine the reference power level for at least one of the plurality of power level modes according to the power receiver setting parameters. The mode circuit is configured to determine a power transfer function between at least one of the parameters of the drive signal and the parameters of the transmitter coil signal and the output power of the power receiver based on the power receiver setting parameters, and to determine the reference power level for the at least one power level mode based on the power transfer function. A power transmitter.

9. The power transmitter according to any one of claims 1 to 8, wherein the mode storage device is configured to store a set of power level modes for different power receivers, and the mode circuit is configured to select the set of power level modes according to an ID indicator received from the power receiver.

10. A power transmitter for wirelessly supplying power to a power receiver via an electromagnetic power transmission signal, a receiver for receiving a message from the power receiver; an output circuit having a transmitter coil for generating the power transmission signal according to a drive signal applied to the output circuit; a drive circuit for generating the drive signal; a power loop controller implementing a power control loop for controlling the drive signal to adjust the power level of the power transmission signal, the power control loop being configured to apply a change to the power level of the power transmission signal according to a power control error message received from the power receiver; A power loop controller; a mode storage device configured to store a plurality of power level modes for the power receiver, each power level mode being associated with a reference power level for the power transmission signal. A mode circuit configured to adapt the drive signal to set the power level of the power transmission signal to a first reference value in response to receiving a mode request message, wherein the first reference value corresponds to a reference power level of a first power level mode indicated in the mode request message among the plurality of power level modes, the mode circuit, having, The power transmission device, wherein the mode request message has a timing index, and the mode circuit is configured to adapt a timing for setting the power level of the power transmission signal according to the timing index. **Claim 11** The power transmission device according to any one of claims 1 to 10, wherein the mode request message is received during a power transmission phase.

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