Wireless power transfer

Abstract

A power transmitter (101) wirelessly supplies power to a power receiver (105) via a power transmission signal. A driver (201) generates the power transmission signal to employ a repetitive time frame that includes a power transmission time interval and a communication time interval. A communication unit (205) and a power transmission coil (103) communicate with the power receiver (105) during the communication time interval by modulating a communication carrier signal. A switching controller (209) controls the drive signal to perform a power level transition between a higher power level during the power transmission time interval and a lower power level during the communication time interval closest to the power transmission time interval. An adapter (211) adapts the rate of change, duration, and / or transition profile of the power level transition according to the power level operating point of the power transmission. For example, a faster transition can be performed at a lower power transmission level compared to a higher power level.

Description

Technical Field

[0001] This invention relates to the operation of wireless power transmission systems. Background Technology

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

[0003] Electricity transfer via magnetic induction is a well-known concept, primarily used in transformers with tight coupling between the primary transmitter inductor / coil and the secondary receiver coil. Wireless power transfer between these devices becomes possible by placing the primary transmitter coil and secondary receiver coil in separate devices, based on the principle of loosely coupled transformers.

[0004] This arrangement allows for wireless power transmission to the device without the need for any wires or physical electrical connections. In practice, it simply allows the device to be placed adjacent to or on top of the transmitter coil for external charging or power supply. For example, the power transmitter device can be arranged on a horizontal surface, and the device can be powered simply by placing it on that surface.

[0005] Furthermore, this wireless power transfer arrangement can be advantageously designed to allow power transmitter devices to be used with a range of power receiver devices. Specifically, a wireless power transfer method known as the Qi specification has been defined. This method allows Qi-compliant power transmitter devices to be used with equally Qi-compliant power receiver devices without these devices needing to be from the same manufacturer or required to be proprietary to each other. The Qi standard also includes features to allow for adaptation of operation based on specific power receiver devices (e.g., depending on specific power consumption). Based on the Qi specification, a method known as the Ki specification is being developed for high-power applications (e.g., specifically for kitchen appliances). Ki (currently) supports much higher power levels, up to 2.5 kW.

[0006] In many systems (specifically the Qi system), communication from a power receiver to a power transmitter can utilize load modulation, where the load on the power transmission signal varies depending on the data to be transmitted. Similarly, communication from a power transmitter to a power receiver can be achieved by modulating the power transmission signal (e.g., amplitude or frequency modulation), but interference with such modulation can be caused by variations in the parameters of the power transmission signal, for example, due to varying loads.

[0007] In some systems, a completely separate communication approach has been proposed accordingly. Specifically, Ki wireless power transmission systems can use the Near Field Communication (NFC) standard to establish a two-way communication link. However, although this communication is separate from power transmission and typically uses very different frequencies, power transmission can still interfere with the communication, especially at higher power levels.

[0008] To mitigate the impact of such interference, periodic interruptions to power transmission have been proposed to create time intervals in which power transmission is shut down and communication is performed. In such methods, communication is typically performed during brief intervals of power transmission interruption during the power transmission phase.

[0009] However, while such a method can provide improved communication, it also has several associated drawbacks. In many scenarios, switching power transmissions can interfere with communication, as well as generate general electromagnetic interference that may affect other nearby electrical equipment, including the circuitry of the power receiver or even the power transmitter itself. Furthermore, because the periodicity of the power transmission interruption intervals tends to be relatively low (e.g., 50 Hz or 100 Hz), the resulting changes in the electromagnetic field occur at low frequencies. In some cases, this can lead to audible noise in the power transmitter, power receiver, and / or other entities.

[0010] Therefore, improved operation of wireless power transmission systems will be advantageous, particularly in allowing for methods that improve flexibility, reduce costs, reduce complexity, improve communication, reduce electromagnetic interference, reduce acoustic noise, improve power transmission, improve efficiency, improve trade-offs, improve functionality and / or improve performance. Summary of the Invention

[0011] Accordingly, the present invention is intended to alleviate, reduce or eliminate one or more of the above-mentioned disadvantages, preferably alone or in any combination.

[0012] According to one aspect of the invention, a power transmitter is provided for wirelessly providing power to a power receiver via an inductive power transmission signal, the power transmitter comprising: a power transmission coil arranged to generate a power transmission signal; a driver arranged to generate a drive signal for the power transmission coil, the driver being arranged to generate the drive signal during a power transmission phase to employ a repetitive time frame, the repetitive time frame including at least a power transmission time interval and a communication time interval; a communication coil arranged to generate a communication carrier signal during the communication time interval; and a communication unit arranged to modulate the power transmission signal with the communication carrier signal during the communication time interval. The receiver communicates; a switching controller is arranged to control the drive signal to perform (or exhibit) a power level transition between a higher power level of the drive signal during a power transmission time interval and a lower power level of the communication time interval closest to (typically adjacent to) the power transmission time interval, the higher power level exceeding the lower power level by at least twice; and an adapter is arranged to adapt the characteristics of the power level transition according to the power level operating point of the power transmission, the characteristics of the power level transition being at least one of the following: the rate of change of the power level transition, the duration of the power level transition, and the transition profile of the power level transition.

[0013] This invention can provide improved performance in many embodiments and overall improved power transmission operation in many systems and embodiments. It can, in particular, reduce electromagnetic interference in many scenarios and can, for example, facilitate or allow compliance with regulatory electromagnetic interference restrictions. In many embodiments, the method can reduce and / or mitigate audible noise caused by power transmission signals (e.g., in the housing or other mechanical parts including the power transmitter or receiver itself). The method can allow for increased efficiency in many scenarios and, in some scenarios, allow for faster switching with less power loss. In many cases, the method can allow for improved trade-offs between conflicting requirements, such as electromagnetic interference / audible or mechanical noise (on the one hand) and power efficiency (on the other hand). In many scenarios, the method can allow for improved adaptation to current conditions and current power transmission.

[0014] In many scenarios, higher power levels may exceed lower power levels by at least five or ten times.

[0015] The switching controller can be configured to switch from a first level to a second level at the beginning of a communication time interval and / or at the end of a power transmission time interval. The switching controller can also be configured to switch from a second level to a first level at the end of a communication time interval and / or at the beginning of a power transmission time interval.

[0016] The switching controller can be configured to switch the drive signal between a power transmission interval power level and a communication interval power level, wherein the power transmission interval power level is the power level of the power transmission signal during the power transmission interval and the communication interval power level is the power level of the power transmission signal during the power transmission interval.

[0017] The power level operating point can be a power control operating point. The power level operating point can be controlled by a power control loop. The power level operating point can be a reserved power level or a power level requested (by the power receiver).

[0018] The driver can be arranged to generate a drive signal, and thus a power transmission signal, having a non-zero amplitude during the power transmission time interval and a zero amplitude during the communication time interval.

[0019] A communication driver can be configured to generate a communication carrier signal with a non-zero amplitude only during the communication time interval.

[0020] The communication time interval closest to the power transmission time interval is usually the communication time interval adjacent to the power transmission time interval.

[0021] According to an optional feature of the invention, the characteristic of the power level transition is the rate of change of the power level transition.

[0022] In many embodiments, this can allow for improved operation and / or facilitate implementation and / or operation. For different operating conditions, it can often provide a particularly advantageous fit and improved trade-off, for example, between electromagnetic interference / audible noise and power transmission efficiency.

[0023] According to an optional feature of the invention, the characteristic is the duration of the power level transition.

[0024] This can provide a particularly advantageous adaptation. In many embodiments, it can allow for particularly efficient and / or convenient implementation. In many embodiments, the parameters can be particularly well-suited for dynamic adaptation.

[0025] According to an optional feature of the invention, the adapter is arranged to increase the duration of the power level transition as the level of the power level operating point increases.

[0026] Depending on the operating conditions, it can often offer a particularly favorable trade-off between, for example, electromagnetic interference / audible noise and power transmission efficiency.

[0027] In many embodiments, the adapter may be arranged to increase the rate of change of the power level transition as the level of the power level operating point increases.

[0028] The power level of the operating point can be the power level of the power transmission at the current operating point.

[0029] According to an optional feature of the invention, the adapter is arranged to: select a first value for the characteristic used for the power level transition for a power level operating point value below a first threshold, and select a second value for the characteristic used for the power level transition for a power level operating point value above a second threshold, wherein the first threshold does not exceed the second threshold.

[0030] This typically ensures acceptable performance while achieving very low implementation complexity.

[0031] In many embodiments, at least one of the first threshold and the second threshold is between 500W and 1kW.

[0032] According to an optional feature of the invention, the characteristic of the power level transition is the transition profile / shape of the power level transition.

[0033] In many embodiments, this can allow for improved operation and / or facilitate implementation and / or operation. Depending on the operating conditions, it can typically provide, for example, an improved trade-off between electromagnetic interference / audible noise and power transmission efficiency.

[0034] The transition profile / shape can be a (normalized) power level as a function of time during the transition interval.

[0035] According to an optional feature of the invention, the adapter is arranged to adapt the transition profile to have reduced higher frequency components as the level of the power level operating point increases.

[0036] In many embodiments, the adapter may be arranged to adapt the transition profile to have reduced energy concentration around harmonic frequencies as the power level operating point increases.

[0037] Depending on the operating conditions, such methods can often provide an improved trade-off between electromagnetic interference / audible noise and power transmission efficiency, for example.

[0038] According to an optional feature of the invention, the power level transition is a transition from the lower power level to the higher power level. The power level transition may be a transition from the communication time interval to the power transmission time interval.

[0039] According to an optional feature of the invention, the power level transition is a transition from the higher power level to the lower power level. The power level transition may be a transition from the power transmission time interval to the communication time interval.

[0040] In many embodiments, this can allow for improved operation and / or facilitate implementation and / or operation. Depending on the operating conditions, it can typically provide, for example, an improved trade-off between electromagnetic interference / audible noise and power transmission efficiency.

[0041] According to an optional feature of the invention, in the power transmitter according to any of the preceding claims, the adapter is arranged to determine the power level operating point based on the power supply characteristics that power at least the output circuit of the power transmission driver.

[0042] In many embodiments, this can allow for improved operation and / or facilitate implementation and / or operation.

[0043] According to an optional feature of the invention, the adapter is arranged to set the power level transition as a step transition in response to determining that the value of the power level operating point is less than a threshold.

[0044] In many embodiments, this can allow for improved operation and / or facilitate implementation and / or operation.

[0045] According to an optional feature of the invention, the power transmitter includes a synchronizer arranged to synchronize the communication time interval with a minimum value of the periodically varying power supply to at least the output circuitry of the power transmission driver.

[0046] According to an optional feature of the invention, the duration of the power level transition does not exceed 5 milliseconds.

[0047] According to an optional feature of the invention, the power transmitter includes a power control loop arranged to control the power level operating point in response to a power control message received from the power receiver.

[0048] According to one aspect of the invention, a method of operating a power transmitter is provided for wirelessly supplying power to a power receiver via an inductive power transmission signal, the method comprising: generating the power transmission signal using a power transmission coil; generating a drive signal for the power transmission coil during a power transmission phase to employ a repetitive time frame, the repetitive time frame including at least a power transmission time interval and a communication time interval; generating a communication carrier signal during the communication time interval using a communication carrier signal; communicating with the power receiver during the communication time interval by modulating the communication carrier signal; controlling the drive signal to perform a power level transition between a higher power level of the drive signal during the power transmission time interval and a lower power level of the communication time interval closest to the power transmission time interval, the higher power level exceeding the lower power level by at least twice; and adapting characteristics of the power level transition according to a power level operating point of the power transmission, the characteristics of the power level transition being at least one of the following: the rate of change of the power level transition, the duration of the power level transition, and the transition profile of the power level transition.

[0049] These and other aspects, features, and advantages of the invention will become apparent and elucidated with reference to one or more embodiments described below. Attached Figure Description

[0050] Embodiments of the invention will be described by way of example only with reference to the accompanying drawings, in which... Figure 1 Examples of elements of a power transmission system according to some embodiments of the present invention are illustrated; Figure 2 Examples of elements of a power transmitter according to some embodiments of the present invention are illustrated; Figure 3 Examples of elements of a power receiver according to some embodiments of the present invention are illustrated; Figure 4 An example of a time frame for a wireless power transmission system according to some embodiments of the present invention is illustrated; Figure 5 The illustration shows an example of power transmission signals and communication carrier signals in a wireless power transmission system; and Figure 6 Examples of methods for interrupting power transmission according to some embodiments of the present invention are illustrated. Detailed Implementation

[0051] The following description focuses on embodiments of the invention applicable to wireless power transmission systems utilizing power transmission methods known, for example, from the Ki specification. However, it should be understood that the invention is not limited to this application, but can be applied to many other wireless power transmission systems.

[0052] Figure 1 An example of a power transmission system according to some embodiments of the present invention is illustrated. The power transmission system includes a power transmitter 101, which includes (or is coupled to) a transmitter coil / inductor 103. The system also includes a power receiver 105, which includes (or is coupled to) a receiver coil / inductor 107.

[0053] The system provides an electromagnetic power transfer signal that can inductively transfer power from a power transmitter 101 to a power receiver 105. Specifically, the power transmitter 101 generates an electromagnetic signal that propagates as a magnetic flux through a transmitter coil or inductor 103. The power transfer signal can correspond to an electromagnetic power transfer component representing the energy transfer from the power transmitter to the power receiver, and can be considered to correspond to the component in the generated electromagnetic field that transfers power from the power transmitter to the power receiver. For example, if the receiving coil 107 is unloaded, the power receiver will not extract power from the generated electromagnetic field (except for losses). In this scenario, driving the transmitter coil 103 can generate a potentially high-intensity electromagnetic field, but the power level of the power transfer signal will be zero (except for losses). In some cases where foreign objects are present, the power transfer signal can be considered to include a component corresponding to the power transferred to the foreign object, and therefore the power transfer signal can be considered to correspond to the power extracted from the electromagnetic field generated by the power transmitter.

[0054] The power transmission signal can typically have a frequency between about 20 kHz and about 500 kHz, and for Ki-compatible systems, it is typically in the range of 20 kHz to 80 kHz. The transmitter coil 103 and the power receiving coil 107 are loosely coupled, and therefore the power receiving coil 107 picks up (at least a portion) of the power transmission signal from the power transmitter 101. Thus, power is transmitted from the power transmitter 101 to the power receiver 105 via wireless inductive coupling from the transmitter coil 103 to the power receiving coil 107. The term "power transmission signal" is primarily used to refer to the induced signal / magnetic field (magnetic flux signal) between the transmitter coil 103 and the power receiving coil 107; however, it should be understood that, equivalently, the term can also be considered and used to refer to the electrical signal provided to the transmitter coil 103 or picked up by the power receiving coil 107.

[0055] In this example, the power receiver 105 is specifically a power receiver that receives power via a receiver coil 107. However, in other embodiments, the power receiver 105 may include a metallic element (e.g., a metallic heating element), in which case the power transmission signal directly induces eddy currents, thereby causing direct heating of the element. Therefore, the power receiver can provide a load to the power transmission signal by including an inductive power extraction element, which may specifically be a power extraction coil or an electrical (e.g., heating) element in which current is induced by the power transmission signal.

[0056] The system is configured to transmit high power levels, and specifically, the power transmitter can support power levels exceeding 50W, 100W, 500W, or 1kW. For example, for Ki-type applications, power transmission can typically exceed 100W, and for very high power applications, it can be as high as 2500W or more.

[0057] In the following description, the operation of the power transmitter 101 and the power receiver 105 will be specifically referenced to embodiments generally based on specifications developed by the Wireless Power Union (in addition to the modifications and enhancements described herein). In particular, the power transmitter 101 and the power receiver 105 may be Ki-compliant components or substantially compatible with Ki-standard components.

[0058] Many wireless power transmission systems (and particularly high-power systems such as Ki) utilize resonant power transmission, where the transmitter coil 103 is part of a resonant circuit, and typically the receiver coil 107 is also part of a resonant circuit. In many embodiments, the resonant circuit can be a series resonant circuit, and thus the transmitter coil 103 and receiver coil 107 can be coupled in series with corresponding resonant capacitors. Using a resonant circuit tends to provide more efficient power transmission.

[0059] Figure 2 The components of the power transmitter 101 are illustrated in more detail. Figure 3 A more detailed illustration is provided. Figure 1 The power receiver 105 is a component.

[0060] The power transmitter 101 includes a driver 201 that can generate a drive signal fed to a transmitter coil 103, which in turn generates an electromagnetic power transmission signal that provides power transmission to a power receiver 105. The power transmission signal is provided (at least) during the power transmission time interval of the power transmission phase.

[0061] The driver 201 may typically include output circuitry in the form of an inverter, as is well known to those skilled in the art, which is typically formed by driving a full-bridge or half-bridge.

[0062] The power transmitter 101 also includes a power transmitter controller 203, which is arranged to control the operation of the power transmitter 101 according to a desired operating principle. Specifically, the power transmitter 101 may include many functions required to perform power control according to the Ki specification.

[0063] The power transmitter controller 203 is specifically arranged to control the generation of drive signals by the driver 201, and it can specifically control the power level of the drive signals, and correspondingly control the level of the generated power transmission signal. The power transmitter controller 203 includes a power loop controller that controls the operating point power level (e.g., average power over a given time interval) of the power transmission signal in response to a power control message received from the power receiver 105 during a power control phase. Therefore, the power level operating point can be adapted in response to the power control message received from the power receiver 105, and the power control loop can be arranged to set / determine / control the power level operating point.

[0064] In order to receive data and messages from power receiver 105, power transmitter 101 includes a first communicator 205, which is arranged to receive data and messages from power receiver 105 and to send data and messages to power receiver 105 (as those skilled in the art will understand, a data message may provide one or more bits of information).

[0065] In this method, communication is performed by modulating a communication carrier signal generated by a first communication coil 207. A first communicator 205 is arranged to generate a communication drive signal, which is fed to the first communication coil 207 to generate a communication carrier signal. The first communicator 205 can typically be arranged to generate a communication drive signal / communication carrier signal having a frequency significantly different from the power transmission drive signal / power transmission signal. In many embodiments, the frequency of the communication carrier signal can be no less than 10 times, 100 times, or 500 times the frequency of the power transmission signal. In many embodiments, the frequency of the communication drive signal / communication carrier signal can have a frequency no less than 500 kHz, 1 MHz, or 10 MHz. Specifically, for an NFC implementation, the communication carrier signal frequency can be 13.56 MHz.

[0066] The first communicator 205 is configured to modulate a communication drive signal / communication carrier signal in order to transmit data to a power receiver (in the following text, references to the communication drive signal also appropriately include implicit references to the communication carrier signal).

[0067] In this specific example, modulation is amplitude modulation of the communication drive signal, and specifically uses binary communication utilizing amplitude shift keying (ASK). However, it should be understood that in other embodiments, modulation may use other methods, such as phase modulation or frequency modulation of the communication drive signal.

[0068] In some embodiments, the first communicator 205 may receive, for example, data to be transmitted to the power receiver from the power transmitter controller 203, and generate a communication drive signal with a corresponding amplitude change in response thereto.

[0069] For communication from a power receiver to a power transmitter, the modulation of the communication drive signal can be load modulation. The power receiver can be arranged to modulate the power transmission signal by changing the load of the power transmission signal generated by the transmitter coil 103 according to the data to be transmitted. The first communicator 205 can be arranged to sense changes in the voltage and / or current of the first communication coil 207 and demodulate the load modulation based on these. Those skilled in the art will understand the principles of load modulation, and therefore will not describe them in further detail.

[0070] In many embodiments, communication may be performed according to the Near Field Communication (NFC) specification, and the power receiver may specifically include NFC functionality. In many embodiments, the first communicator 205 and the first communication coil 207 may (at least) implement the functionality of an NFC reader. Therefore, in many embodiments, the communication drive signal / communication carrier signal is a 13.56MHz signal at a constant level (except for modulation).

[0071] The following description will focus on an example in which communication between the power transmitter and the power receiver is carried out via NFC communication, and specifically, where NFC carrier modulation in the direction from the power transmitter to the power receiver is performed by amplitude shift keying (ASK), while NFC carrier modulation in the direction from the power receiver to the power transmitter is performed by load modulation.

[0072] exist Figures 1 to 3 In this system, communication is performed within communication time intervals during the power transmission phase. Specifically, the transmitter controller 203 may include / implement a synchronizer 206 arranged to synchronize the first communicator 205 such that communication operations (typically both receiving and transmitting data) are performed within the communication time intervals of the power transmission phase (and typically only within the communication time intervals of the power transmission phase), i.e., within the time intervals allocated for communication. This can significantly improve communication performance and, in particular, reduce interference from power transmission signals to communication.

[0073] This method can utilize a time-division approach during the power transmission phase, where communication (and possibly other operations such as foreign object detection) and power transmission can be performed in different time intervals, thereby allowing interference between them (specifically, the impact of power transmission on foreign object detection / communication) to be significantly reduced.

[0074] Specifically, for wireless power transmission systems, the power transmission signal passes through a repeating time frame that includes at least one power transmission time interval and one communication time interval.

[0075] The power transmitter can be arranged to reduce the power level of the power transmission signal during the communication interval, and in many embodiments, the power transmission signal can be completely shut off. In some embodiments, the power receiver can be arranged to disconnect the load during the communication interval.

[0076] The power transmitter (and typically the power receiver) can then be scheduled to perform one or more operations (functions, procedures, processes) during the communication interval; that is, the execution of one or more operations of the power transmitter can be synchronized to occur during the communication interval. For example, it can typically synchronize the performance of foreign object detection and communication to occur during the communication interval. In this way, the impact of power transmission and the power transmission signal on a given operation (specifically foreign object detection and communication) can be reduced and generally minimized.

[0077] Figure 3 Some exemplary components of the power receiver 105 are illustrated.

[0078] Receiver coil 107 is coupled to power receiver controller 301, which couples receiver coil 107 to load 303 via switch 305 (i.e., switchable load 305). Power receiver controller 301 includes a power control path that converts the power extracted by receiver coil 107 into a power supply suitable for load 303. Furthermore, power receiver controller 301 may include various power receiver controller functions required to perform power transmission, and in particular, functions required to perform power transmission according to the Ki specification.

[0079] To support communication from the power receiver 105 to the power transmitter 101, the power receiver 105 includes a second communicator 307 and a second communication coil 309. The second communication coil 309 is arranged to be coupled to the first communication coil 207, and thus the communication carrier signal induces a current (at least an electromotive force) in the second communication coil 309.

[0080] The second communicator 307 is coupled to the second communication coil 309 and is arranged to determine amplitude changes in the induced signal and demodulate the amplitude modulation of the communication carrier signal. Therefore, the second communicator 307 is arranged to decode data transmitted from the power transmitter by amplitude modulation of the communication carrier signal. It should be understood that in other embodiments, the second communicator 307 may be arranged to decode data modulated onto the communication carrier signal using other modulation formats (e.g., frequency modulation or phase modulation).

[0081] The second communicator 307 is also configured to perform load modulation on the communication carrier signal to transmit data from the power receiver to the power transmitter. Specifically, the second communicator 307 may include a load (e.g., a capacitor) that can be switched between being coupled to and not coupled to the second communication coil 309, depending on the data to be transmitted. These load modulations can then be detected by the first communicator 205 of the power transmitter.

[0082] In a specific example, the second communication coil 309 and the second communicator 307 can provide NFC-compatible communication operations. Specifically, the second communication coil 309 can be arranged to provide functions corresponding to an NFC tag and to decode data that has been modulated onto a communication carrier signal according to the NFC specification.

[0083] Therefore, the second communicator 307 is arranged to transmit data to the power transmitter by changing the load of the receiver coil 107 in response to data to be transmitted to the power transmitter 101. As known to those skilled in the art, the load change is then detected and demodulated by the power transmitter 101.

[0084] In this example, the second communicator 307 is also configured to demodulate the amplitude modulation, frequency modulation, and / or phase modulation of the communication carrier signal in order to retrieve data transmitted from the power transmitter.

[0085] As described above, the system applies a recurring time frame during the power transmission phase, wherein the time frame includes at least one power transmission time interval and at least one communication time interval. Figure 4 The diagram illustrates an example of such a repeating timeframe, where the power transmission time interval is indicated by PT and the communication time interval by C. In this example, each timeframe FRM includes only one communication time interval and one power transmission time interval. However, it should be understood that in other embodiments, other time intervals may also be included in the timeframe, or multiple communication time intervals and / or power transmission time intervals may be included in each timeframe.

[0086] The power transmission driver 201 is controlled by the power transmitter controller 205 to generate only a drive signal with full power during the power transmission time interval, and to significantly reduce power during the communication time interval, and typically shut down the power transmission signal. Therefore, in many embodiments, the driver 201 generates a drive signal and thus a power transmission signal during the power transmission time interval, while shutting down the drive signal and thus the power transmission signal during the communication time interval.

[0087] During the power transmission phase, the power transmitter is therefore arranged to perform power transmission during power transmission time intervals within the time frame of the power transmission phase. Specifically, during these time intervals, the power transmitter and power receiver can operate a power control loop (which can be based on communication in a communication time interval corresponding to the repetitive time interval). Therefore, the level of the transmitted power can be dynamically changed.

[0088] However, during the communication time interval of the power transmission phase time frame, the power drive signal is significantly reduced and usually turned off, and therefore no power transmission signal is generated (or a reduced power level is generated) during the communication time interval.

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

[0090] In this system, the first communicator 205 is therefore arranged to transmit only data during the communication time interval, and thus modulates only the communication carrier signal (e.g., amplitude). Similarly, it typically only attempts to demodulate the data during the communication time interval.

[0091] Similarly, the second communicator 307 is arranged to communicate only during the communication time interval when the power transmission phase is in progress. In this system, the second communicator 307 is therefore arranged to transmit only data during the communication time interval and thus only perform load modulation on the communication carrier signal. Likewise, it typically only attempts to demodulate data during the communication time interval.

[0092] Therefore, during the power transmission phase, the first communicator 205 and the second communicator 307 are arranged to communicate only during the communication time interval. This method provides highly advantageous performance and has been found to offer significantly improved communication performance. In particular, the method reduces interference from power transmission signals on communication operation, thereby providing more reliable and robust communication with reduced bit errors.

[0093] In many embodiments, the power drive 201 can be powered by a time-varying supply signal. Specifically, the supply voltage of the output stage can be generated from an AC voltage (e.g., specifically from an AC mains voltage). In some embodiments, the AC voltage can be directly used as the supply voltage for the output circuitry (e.g., an inverter) of the power drive 201. In many embodiments, the supply voltage may alternatively be generated as a rectified mains voltage. Therefore, in many embodiments, the (absolute) supply voltage varies as a (possibly rectified) sine wave with a given period. As a result, the generated power transmission drive signal has a characteristic such as... Figure 5 and 6 The amplitude shown is a (sine wave) time-varying amplitude. The amplitude has a minimum value (typically zero) corresponding to the zero-crossing point of the input supply voltage and specifically to the zero-crossing point of the AC mains voltage. Therefore, the power transmission drive signal / power transmission signal is generated as an amplitude period with half the period of the AC mains signal.

[0094] In such an embodiment, the repetitive time frame, and therefore the power transmission time interval and communication time interval, can be synchronized with the changing power supply signal, and thus with the timing of the amplitude changes of the power transmission drive signal. In particular, the communication time interval can be arranged at (including) the minimum value of the amplitude (corresponding to the zero crossing point of the mains signal).

[0095] Similarly, the communication driver 209 is arranged to generate a communication carrier signal synchronized with the changing power supply signal, and specifically, it can be activated around the minimum power supply.

[0096] Therefore, in many embodiments, the repetition time frame, the power transmission time interval, and the communication time interval (specifically in the power transmitter) are synchronized with the time-varying power supply signal, and specifically with the mains power supply.

[0097] Figure 5 The figure illustrates an example of how communication can be performed in a communication time interval of a repetitive time frame in such a manner. The figure shows a power transmission signal 501 generated during the power transmission time interval PT and a modulated communication carrier signal 503 generated during the communication time interval C. Figure 5 A time-division multiplexing mechanism was implemented between power transmission and communication, in which each operation was performed in a dedicated time interval.

[0098] Figure 6 The illustration shows an example of a method to interrupt power transmission. Figure 6The diagram illustrates the power supply signal (voltage / current / power) 601 provided to the output circuit / inverter of driver 201. In this example, this is a rectified AC signal, thus having a minimum value (specifically, reaching zero) at periodic intervals. Communication time intervals 603, 605 are positioned around the minimum value, and a power transmission time interval 607 occurs between communication time intervals 603, 605. In this example, the envelope / amplitude of the drive signal 609, and therefore the power transmission signal, follows the power supply signal 601 during the power transmission time interval 607 (and...). Figure 6 In the example, except during transition time intervals 611 and 613, it is scaled to match the power supply signal 601.

[0099] The transition time interval is used to transition the power level of a drive signal / power transmission signal from the power level applied during the power transmission time interval to the power level applied during the communication time interval. During the transition time interval, the power level is typically rapidly decreased / increased to change from the power level of the communication time interval to the power level of the power transmission time interval, and vice versa. Figure 6 As shown, during the transition time interval, the drive signal 609 can have a higher rate of change than the power supply signal 601. The transition time interval provides a faster transition compared to simply following a rectified power supply (in which case no communication time interval would actually be generated). Therefore, a fast transition is typically performed to change the power level between the power transmission time interval and the adjacent communication time interval (in either direction). The transition time interval can be considered as part of the power transmission time interval, or it can be considered as not part of the transition time interval.

[0100] In this method, the power transmitter includes a switching controller 209, which is arranged to control (generated by driver 201) a drive signal to perform a power level transition between a higher power level of the drive signal during a power transmission time interval and a lower power level during a communication time interval adjacent to the power transmission time interval. Therefore, the switching controller 209 controls the transition of the drive signal / power transmission signal between the power transmission time interval and the communication time interval. In some cases, the switching controller 209 may directly control the driver 201, for example, by directly providing a control signal adapted to the power level. For example, the driver 201 may have a control input for control by both the switching controller 209 and the power transmitter controller 203. In other embodiments, the switching controller 209 may, for example, control the power transmitter controller 203 to control the driver 201. For example, the switching controller 209 may provide control data (e.g., the duration of the transition time interval) to the power transmitter controller 203, which may adapt to control of the driver 201 in response to the received control data.

[0101] In many embodiments, control of the power level of the drive signal / power transmission signal can be achieved by adapting / controlling, for example, the current or voltage of the generated drive signal. However, in many embodiments, the power level can be controlled by a power transmitter controller 203 that controls the duty cycle and / or frequency and / or burst mode of the generated drive signal. In burst mode operation, power can be controlled by not transmitting power for the entire available power transmission time interval, i.e., the drive signal / power transmission signal can be generated only in bursts within the power transmission time interval (in some cases, this can be considered equivalent to, for example, increasing one or both of the transition time intervals 611, 613 (e.g., not generating power during some portions of transition time intervals 611, 613)). Power extracted by the power receiver is used for a resonant power transmission system that is highly dependent on the drive frequency, and changing / adapting the frequency provides an efficient method for controlling the power level. Similarly, the duty cycle and burst mode provide efficient control of the power level of the wireless power transmission system. In many embodiments, the power control loop can be arranged to control at least one of the duty cycle and frequency of the drive signal.

[0102] The power transmitter also includes an adapter 211 coupled to the switching controller 209 and arranged to adapt the characteristics of power level switching based on the power level operating point of the power transmission. Therefore, the power transmitter is arranged to dynamically adapt switching operation based on the operating point power level of the power transmission, rather than performing a predetermined or constant switching. In many cases, the power level operating point can be determined by the duty cycle, burst mode, and / or frequency of the drive signal (typically set by the power control loop), and the switching characteristics can be related to the frequency, burst mode, and / or duty cycle of the (typically predetermined) drive signal.

[0103] Adapter 211 can be specifically arranged to adapt the transition profile such that the curve representing the power level of the drive signal has reduced high-frequency content for high-power transmission than for low-power transmission, and / or has a more uniform distribution, and particularly has reduced energy concentration around harmonics (and particularly harmonics of the supply frequency). For example, if the power transmission is currently operating at a relatively low power extracted by the power receiver, the transition can be adapted to a rapid (e.g., linear) transition (and in extreme cases, such as directly turning the drive signal on or off). Furthermore, the lengths of the transition time intervals 611 and 613 can vary within a single power interval, which can have a favorable effect on power transmission efficiency. However, if the power transmission is currently operating at a relatively high power extracted by the power receiver, the transition can be adapted to a slow transition of a shaped profile that is smooth and has increased low-to-high frequency content and / or less energy concentration around harmonics.

[0104] This method can provide improved performance and / or operation in many embodiments and applications. In many scenarios, this may lead to trade-offs between different and conflicting preferences, such as increased efficiency, reduced electromagnetic interference, reduced mechanical noise, etc. In particular, this method can allow for a more appropriate and generally improved trade-off between acoustic noise and electromagnetic interference that may cause to other electronic devices on one hand, and efficiency and power loss on the other.

[0105] To generate the effect of cutting off the drive signal / power transmission signal, as mentioned above, the communication time interval can be synchronized near the zero-crossing point of the mains power, thereby reducing or minimizing the magnitude of power changes during the transition time interval. However, direct switching of power can potentially generate large harmonics and may result in electromagnetic fields / signals with significant amplitudes of electromagnetic interference at potentially quite high frequencies. Such interference can significantly affect other nearby electronic circuits and may not meet current stringent regulatory specifications such as EMI (electromagnetic interference).

[0106] Furthermore, it has been found that direct on / off switching often results in audible noise from the transmitter coil. For example, the switching may cause changes in the electromagnetic field, which could induce movement in nearby metal components, potentially causing acoustic noise. This can be particularly noticeable because the induced movement may, in some cases, approach the resonant frequency of many practical mechanical structures.

[0107] To address this issue, a more gradual transition can be implemented instead of a step-on / off switch, where the power level does not change immediately but transitions over a period of time. This can also be referred to as... Figure 6 The ramp shown depicts the rise and fall of the frequency response. This allows induced harmonics to be reduced and / or spread across the frequency spectrum. This transition can be designed to allow compliance with EMI specifications (which are frequency-dependent). Specifically, it allows the transition to spread / distribute harmonics from the rectified mains signal across the frequency spectrum, thereby meeting the required EMI limits. Additionally, it typically reduces the risk of audible noise reduction and the risk of the generated electromagnetic field having a strong component corresponding to the mechanical resonant frequency of the enclosure of, for example, near-side devices (including power receivers and power transmitters).

[0108] However, the disadvantages of this slow transition include its potential to affect power transmission and, for example, alter its behavior and operation. Importantly, slow switching / transition can also reduce the efficiency of power transmission. This can be explained as follows (e.g., the half-bridge switch / output circuit of driver 201): Wireless power systems utilize resonant systems / currents to be as efficient as possible. For the system to be efficient, a minimum amount of energy / current is required in the system to resonate from one state to another (natural transition). If this energy is not present, then the switch needs to force the resonant circuit to transition from one state, which is called hard switching. Due to the rapid transition, hard switching comes at the cost of energy loss and high-frequency noise.

[0109] Typically, switching at lower power levels is relatively inefficient because a certain amount of current is required for effective switching. From this perspective, it is desirable to avoid operating with low power / current. Switching in this situation often leads to inefficient operation because it is inherently low-current operation. Therefore, faster switching generally results in higher efficiency and relatively less power loss.

[0110] The inventors not only recognized these problems, but also realized that improved performance can often be achieved through dynamic adaptation based on (one or more) transitions in the operating point of the power transmission power level. In particular, they have recognized that this can provide improved trade-offs in many scenarios and embodiments. For example, transitions can be dynamically adapted so that operation reflects the most critical parameters for a given situation. For instance, EMI and audible noise may often pose more significant problems at higher power transmission levels, while efficiency losses may be more problematic in many cases at lower power transmission levels. Adapter 211 can be arranged to adapt accordingly, such that relative mitigation of undesirable effects is adapted to reflect their relative criticality.

[0111] Adapter 211 can, for example, adapt the switching time according to the requested / sent electrical power. For instance, under high power, a relatively long switching time can be maintained to keep mains harmonics / EMI below desired limits and reduce the risk of audible noise. Under low power, the switching time can be set short, or even essentially zero, to ensure more efficient operation and reflect that harmonics / EMI and audible noise are generally acceptable simply due to the lower power level.

[0112] Therefore, the adaptation of switching operations can be dynamically updated based on the (power level) operating point of power transmission to provide improved performance as well as a compromise between different and conflicting preferences.

[0113] In some embodiments, the power level during the power transmission time interval can be constant. For example, a fixed voltage power supply can be applied to the output circuit of driver 201, and the resulting drive signal can have a constant amplitude during the power transmission time interval. However, in many embodiments, the power level during the power transmission time interval can vary, for example, specifically having a sinusoidal shape generated by the sinusoidally varying power supply to driver 201.

[0114] In many embodiments, the power level during the communication time interval can be (substantially) zero, where the drive signal is completely turned off. However, in some embodiments, a drive signal can be generated during the communication time interval, but with a (lower) power level.

[0115] The power level during the communication interval does not exceed the power level during the power transmission interval, and typically the power level during the power transmission interval (outside of the transition interval) is not less than, for example, 2, 5, or 10 times the maximum power level during the (adjacent) communication interval.

[0116] In many embodiments, driver 201 may be arranged to generate a drive signal having a power level not lower than a first power level threshold during at least a portion of a power transmission time interval, and a power level not exceeding a second power level threshold during at least some communication time intervals. The first power level threshold is not less than a first threshold and is typically not less than 2, 5, or 10 times higher.

[0117] In this example, the transition controller 209 is arranged to apply a dynamically changing transition method both for transitions from a communication time interval to a power transmission time interval and for transitions from a power transmission time interval to a communication time interval, and thus for transition time intervals from / to a power transmission time interval and from / to a communication time interval. However, it should be understood that in some embodiments, the method may be applied only to some transition time intervals, for example, specifically only to transition time intervals at the beginning or end of a transition time interval (or communication time interval).

[0118] The duration of the transition time interval can vary dynamically. However, in many embodiments, the duration of the transition time interval does not exceed 5 milliseconds, 10 milliseconds, or 25 milliseconds. In many embodiments, the minimum duration of the transition time interval is not less than 100 microseconds, 500 microseconds, or 1 millisecond.

[0119] The power level of the driver 201 signal can correspond to the current / instantaneous amplitude of the drive signal (e.g., determined as power, current, and / or voltage). It can be the average current / instantaneous power over the period of the power transmission signal (at the drive frequency).

[0120] A transition time interval can be a time interval during which the power level changes between a given power transmission time interval and the power level of the communication time interval closest to the power transmission time interval / transition time interval. Typically, the power transmission time interval and the communication time interval are adjacent to each other and separated only by the transition time interval (or equivalently, the transition time interval can be considered the closest / adjacent end portion of the power transmission time interval to the communication time interval). In some cases, only a portion of the communication time interval can be used for communication. For example, in some cases, the size of the power transmission time interval can be reduced, thereby extending the communication time interval with reduced power beyond the communication reserved / used time interval. Equivalently, the power transmission time interval and the closest communication time interval can be considered to be separated by one or more time intervals during which other (or no) operations are performed and the communication time interval is maintained at a low power level.

[0121] exist Figure 6In the examples, the transition profile is a linear change from the initial power level to the final power level. For the transition from a communication time interval to a power transmission time interval (transition time interval 611), the initial power level is very small and can be essentially zero, while the power transmission power level at the end of the transition time interval is a significantly higher value, and in this particular example corresponds to the level determined by the changing power supply. For the transition from a power transmission time interval to a communication time interval (transition time interval 613), the initial power level is a high value, and in this particular example corresponds to the level determined by the changing power supply, while the power transmission power level at the end of the transition time interval is very small and can be essentially zero.

[0122] In many cases, when the parameters used to control the power level have reached the same value as the midpoint of the power transmission time interval, the power level of the power transmission time interval can correspond to the level of the drive signal / power transmission signal. In many scenarios, it can correspond to the maximum power level setting of the parameters controlling the power level (of the power transmission time interval). Specifically, it can correspond to the power level when the transition values ​​of control parameters (e.g., frequency, burst mode, and / or duty cycle) are at values ​​determined for / applied to the remainder (and / or middle) of the power transmission time interval.

[0123] Similarly, for the transition from a power transmission interval to a communication interval, the ending power level is very small and can be essentially zero, while (similar to the previous description) the power transmission power level at the start of the transition interval is a significantly higher value.

[0124] In many embodiments, adapter 211 may be arranged to adapt to the timing characteristics of the transition. In particular, adapter 211 may be arranged to adapt to the rate of change and / or duration of the transition based on the operating point of the power transmission.

[0125] For example, the transformation could be like Figure 6 The power level is shown as a linear increase or decrease. In this case, the duration of the transition can be determined based on the current power level operating point. For example, the duration can be determined as a monotonically increasing function of the current power transmission level. Equivalently, the rate of change of the transition can be determined as a monotonically decreasing function of the current power transmission level.

[0126] As a specific example, if the current power transmission level corresponds to power receiver extraction exceeding a given power threshold, then adapter 211 can set the transition time / rate of change to a given predetermined value, and if the current power transmission level corresponds to power receiver extraction less than the given power threshold, then adapter 211 can set the transition time / rate of change to a different predetermined value.

[0127] In many embodiments and scenarios, such thresholds are advantageously located in the range of 500W to 1000W (e.g., the power as a drive signal / power extracted from the power transfer signal is measured). Specifically, for power levels below 500W, EMI and acoustic noise are generally acceptable and meet requirements, while this is generally not the case for power levels above 1000W. The duration of transitions in power transfer levels above 1000W can generally be no less than 2 milliseconds. The duration of transitions in power transfer levels below 500W can generally be no more than 500 microseconds and can generally be set to be substantially instantaneous (i.e., direct transition).

[0128] In many embodiments, adapter 211 can be arranged to set the transition as a step transition when the power delivery level is sufficiently low (e.g., if it is less than a given threshold). Such a step transition is generally advantageous in terms of allowing low-complexity operation and reducing switching losses. Therefore, for low power delivery levels, simple switching without a ramp can be applied, and ramp / gradual transitions are limited to scenarios where the power delivery level may be significant and cause unacceptable effects.

[0129] In some embodiments, adapter 211 may be arranged to adapt to a transition profile / shape of the transition. The transition profile may be a change / modification of power level as a function of time during the transition time interval (a function representing that change / modification). Specifically, the change / modification may be a normalized change / modification (normalized relative to the total change in power level). In many such scenarios, the transition profile may be considered the shape of the transition.

[0130] exist Figure 6 In the example, the transition profile is a linear change from the initial power level to the final power level. In some cases, the duration can be dynamically changed based on the power level operating point while still maintaining a linear profile. However, in other cases, the shape / profile can be modified to result in different overall frequency distributions of the resulting power transmission signal, and specifically, a modified electromagnetic interference frequency distribution. For example, in some embodiments, a smoother transition profile can be selected, particularly with a smoother fit to the power levels of the power transmission time interval and the communication time interval. For example, the rate of change / derivative of the power level at the end of the transition time interval can be designed to more closely match the derivatives of the power levels during the communication time interval and the power transmission time interval, respectively. In particular, the rate of change of the power level at the end / beginning of the transition time interval adjacent to the communication time interval can be controlled to be close to zero.

[0131] The shaping and timing of the power level during the transition time interval can be controlled to achieve a desired spectrum for the resulting drive / power transfer signal. Specifically, the transition can be controlled to generate a drive / power transfer signal that reduces mains harmonics and provides a smoother spectrum, while also typically reducing higher frequency components. Such an approach generally allows for better EMI compliance and often enables the fulfillment of stringent regulatory requirements. The reduction in harmonics and the smoother spectrum also significantly reduces the risk of exciting mechanical resonances, thereby lowering the probability of generating audible noise.

[0132] In this method, the resulting drive signal (and corresponding power transmission signal) can be considered as the product of the original drive signal multiplied by a window function that creates the communication time interval and the transition time interval. In this example, the original drive signal is a full-wave rectified sine wave. The frequency of this signal has a large number of harmonics of the original sine wave, i.e., in the current case, typically a 50Hz or 60Hz sine wave from the mains power supply. In fact, the full-wave rectified signal can be considered as the result of a sine wave multiplied by a square wave with corresponding frequencies (having values ​​of +1 and -1). Therefore, the spectrum is the correlation between a single frequency and a sinc(f) function, which is itself a sinc function.

[0133] Using an instantaneous switch corresponds to a window function of sinc(f), so the resulting windowed drive / power transmission signal will have a spectrum given by the correlation between the sinc(f) function and the frequency distribution of the original drive signal, which in a specific example is also a sinc(f) function. Therefore, in this case, the spectrum is the correlation of two sinc(f) functions, which makes the spectrum tend to have a significant harmonic structure (especially since both sinc(f) functions are generated by the same fundamental periodicity (from the mains supply). Thus, using a hard switch causes energy concentration near the harmonic frequencies. This may be acceptable for lower power transmission levels, but can be very detrimental for higher power transmission levels and, for example, can hinder compliance with regulatory EMI requirements.

[0134] Conversely, if a window function with less periodicity and generally more concentrated at lower frequencies is used, the resulting correlation will result in a more spread and uniform distribution of energy rather than concentration around harmonics. It can also allow more energy to be concentrated at lower frequencies. In particular, in many embodiments, using a window function with a frequency distribution of energy concentrated at lower frequencies but extending to a sinc(f) function sufficient to spread the full-wave rectified signal yields a (more) smooth / more uniform spectrum.

[0135] For example, applying a linear transform can often yield more spread / dispersed energy in the frequency domain, with reduced harmonic components. Even more uniform distributions can often be achieved by using other shapes. For instance, shapes known from window functions such as the Hanning, Hamming, and Hann windows can be used, and often provide a more favorable frequency distribution. One or more transform profiles can specifically be chosen as half of a symmetric window function (e.g., the Hanning, Hamming, Hann, Welch, B-spline, etc.).

[0136] In some embodiments, adapter 211 may be arranged to switch between different transition profiles based on the power level operating point. For example, for power delivery levels below a given threshold, adapter 211 may control the transition profile to, for example, a triangular / linear transition profile (with, for example, a fast transition time). If the power delivery level is above the threshold, then adapter 211 may instead control the transition profile to correspond to, for example, a Hamming window, and may have a slower transition time.

[0137] As previously mentioned, the power level operating point can be an operating point controlled by a power control loop in many embodiments. It can be a power control power level set specifically by the power control. Therefore, the power level operating point can be set / determined in response to / based on power control messages received from the power receiver.

[0138] In many embodiments, the power level operating point can be determined based on the power supplied to the output circuitry of driver 201. For example, adapter 211 can be arranged to measure the power supply characteristics of at least the output circuitry of the power transmission driver. The power supply can be averaged over suitable intervals (e.g., over one or more power transmission time intervals), and the resulting average input power supply can be used as a measure of the power level operating point.

[0139] In some cases, the power level operating point can be a measure of the power extracted from the power transmission signal via a power receiver. The power level operating point can be a measure / quantity of the power in the power transmission signal / the extracted power. This power measure / quantity can be an average / median measure / quantity over at least one communication time interval.

[0140] In some embodiments, the power level operating point may not be a dynamic measurement, but may be determined, for example, as the desired or requested power for wireless power transmission. For instance, the power level operating point may be reserved power for power transmission or power requested by a power receiver. In some cases, the power level operating point may be a constant value for power transmission, or in many embodiments, it may be a variable value that reflects changes in the operating point / power transmission level.

[0141] It should be understood that, for clarity, the above description has referenced various functional circuits, units, and processors to describe embodiments of the invention. However, it will be apparent that any suitable functional distribution among different functional circuits, units, or processors can be used without departing from the invention. For example, a function illustrated as being performed by a separate processor or controller may be performed by the same processor or controller. Therefore, references to specific functional units or circuits are considered merely as references to suitable units used to provide the described functions, and not as indications of a strict logical or physical structure or organization.

[0142] This invention can be embodied in any suitable form, including hardware, software, firmware, or any combination thereof. The invention can optionally be implemented, at least in part, as computer software running on one or more data processors and / or digital signal processors. Elements and components of embodiments of the invention can be implemented physically, functionally, and logically in any suitable manner. In practice, functionality can be implemented in a single unit, in multiple units, or as part of other functional units. Therefore, the invention can be implemented in a single unit or can be physically and functionally distributed among different units, circuits, and processors.

[0143] While the invention has been described in conjunction with some embodiments, it is not intended to be limited to the specific forms set forth herein. Rather, the scope of the invention is limited only by the appended claims. Additionally, although it may appear that features have been described in conjunction with specific embodiments, those skilled in the art will recognize that various features of the described embodiments can be combined according to the invention. In the claims, the term includes the notation that the presence of other elements or steps is not excluded.

[0144] It should be understood that a reference to a preferred value does not imply any limitations beyond the value determined in the foreign object detection initialization mode; that is, it is preferred because it was determined during the adaptation process. A reference to a preferred value can replace a reference to, for example, a first value.

[0145] Furthermore, although listed separately, multiple means, elements, circuits, or method steps can be implemented by, for example, a single circuit, unit, or processor. Additionally, while individual features may be included in different claims, these features can be advantageously combined, and inclusion in different claims does not imply that such a combination is infeasible and / or disadvantageous. Moreover, the inclusion of a feature in one claim class does not imply a limitation on that class, but rather indicates that the feature is equally applicable to other claim classes where appropriate. Furthermore, the order of features in a claim does not imply that these features must be performed in any particular order, and in particular, the order of steps in a method claim does not imply that the steps must be performed in that order. Rather, the steps can be performed in any suitable order. Furthermore, singular references do not exclude plural. Therefore, references to “a,” “an,” “first,” “second,” etc., do not exclude plural. Reference numerals in the claims are provided as illustrative examples only and should not be construed as limiting the scope of the claims in any way.

[0146] In general, examples of power transmitters and their operating methods are indicated by the following embodiments.

[0147] Example: Example 1: A power transmitter (101) for wirelessly providing power to a power receiver (105) via an inductive power transmission signal, the power transmitter (101) comprising: A power transmission coil (103) is arranged to generate the power transmission signal; A driver (201) is arranged to generate a drive signal for the power transmission coil (103), the driver (201) being arranged to generate the drive signal during a power transmission phase to employ a repetitive time frame, the repetitive time frame including at least a power transmission time interval and a communication time interval. A communication coil (207) is arranged to generate a communication carrier signal during a communication time interval; A communication unit (205) is arranged to communicate with the power receiver (105) during a communication time interval by modulating the communication carrier signal; A switching controller (209) is arranged to control the drive signal to perform a power level switching between a higher power level of the drive signal during a power transmission time interval and a lower power level of a communication time interval closest to the power transmission time interval, wherein the higher power level exceeds the lower power level by at least twice; and An adapter (211) is arranged to adapt to the characteristics of the power level transition according to the power level operating point of the power transmission.

[0148] Example 2: The power transmitter according to Example 1, wherein the characteristic of the power level transition includes the timing characteristic of the transition.

[0149] Example 3: The power transmitter according to Example 2, wherein the timing characteristic is at least one of the rate of change and duration of the transition.

[0150] Example 4: A power transmitter according to Example 2 or 3, wherein the adapter (211) is arranged to increase the duration of the transition as the level of the power level operating point increases.

[0151] Example 5: A power transmitter according to any of the preceding embodiments, wherein the adapter (211) is arranged to: select a first value for the characteristic of the power level transition for a power level operating point value below a first threshold, and select a second value for the characteristic of the power level transition for a power level operating point value above a second threshold, wherein the first threshold does not exceed the second threshold.

[0152] Example 6: A power transmitter according to any of the foregoing embodiments, wherein the characteristic of the power level transition is a transition profile.

[0153] Example 7: The power transmitter according to Example 6, wherein the adapter (211) is arranged to adapt the transition profile to have a reduced higher frequency component as the level of the power level operating point increases.

[0154] Example 8: A power transmitter according to any of the foregoing embodiments, wherein the power level transition is a transition from the lower power level to the higher power level.

[0155] Example 9: A power transmitter according to any of the preceding Examples 1-7, wherein the power level transition is a transition from the higher power level to the lower power level.

[0156] Example 10: A power transmitter according to any of the preceding embodiments, wherein the adapter (211) is arranged to determine the power level operating point based on the power supply characteristics that supply power to at least the output circuit of the driver (201).

[0157] Example 11: A power transmitter according to any of the preceding embodiments, wherein the adapter (211) is arranged to set the power level transition as a step transition in response to determining that the value of the power level operating point is less than a threshold.

[0158] Example 12: A power transmitter according to any of the preceding embodiments, including a synchronizer (203) arranged to synchronize the communication time interval with a minimum value of the periodically varying power supply to at least the output circuit of the power transmission driver.

[0159] Example 13: A power transmitter according to any of the foregoing embodiments, wherein the duration of the power level transition does not exceed 5 milliseconds.

[0160] Example 14: A power transmitter according to any of the preceding embodiments includes a power control loop arranged to control the power level operating point in response to a power control message received from the power receiver (105).

[0161] Example 15: A method of operating a power transmitter (101) for wirelessly supplying power to a power receiver (105) via an inductive power transmission signal, the method comprising: The power transmission coil (103) generates the power transmission signal; During the power transmission phase, a drive signal for the power transmission coil (103) is generated to employ a repetitive time frame, which includes at least a power transmission time interval and a communication time interval. The communication coil (207) generates a communication carrier signal during the communication time interval; During the communication time interval, communication is conducted with the power receiver (105) by modulating the communication carrier signal; Controlling the drive signal to perform a power level transition between a higher power level of the drive signal during a power transmission time interval and a lower power level during a communication time interval closest to the power transmission time interval, wherein the higher power level exceeds the lower power level by at least twice; and The characteristics of adapting the power level transition are based on the power level operating point of the power transmission.

[0162] More specifically, the invention is defined by the appended claims.

Claims

1. A power transmitter (101) for wirelessly supplying power to a power receiver (105) via an inductive power transmission signal, the power transmitter (101) comprising: A power transmission coil (103) is arranged to generate the power transmission signal; A driver (201) is arranged to generate a drive signal for the power transmission coil (103), the driver (201) being arranged to generate the drive signal during a power transmission phase to employ a repetitive time frame, the repetitive time frame including at least a power transmission time interval and a communication time interval. A communication coil (207) is arranged to generate a communication carrier signal during a communication time interval; A communication unit (205) is arranged to communicate with the power receiver (105) during a communication time interval by modulating the communication carrier signal; A switching controller (209) is arranged to control the drive signal to perform a power level switching between a higher power level of the drive signal during a power transmission time interval and a lower power level of a communication time interval closest to the power transmission time interval, wherein the higher power level exceeds the lower power level by at least twice. as well as An adapter (211) is arranged to adapt the characteristics of the power level transition according to the power level operating point of the power transmission, the characteristics of the power level transition being at least one of the following: The rate of change of the power level transition The duration of the power level transition, and The transition profile of the power level shift.

2. The power transmitter according to claim 1, wherein, The characteristic of the power level transition is the rate of change of the power level transition.

3. The power transmitter according to claim 1, wherein, The characteristic is the duration of the power level transition.

4. The power transmitter according to claim 2 or 3, wherein, The adapter (211) is arranged to increase the duration of the power level transition as the level of the power level operating point increases.

5. The power transmitter according to any of the preceding claims, wherein, The adapter (211) is arranged to: select a first value for the characteristic of the power level transition for a power level operating point value below a first threshold, and select a second value for the characteristic of the power level transition for a power level operating point value above a second threshold, wherein the first threshold does not exceed the second threshold.

6. The power transmitter according to any of the preceding claims, wherein, The characteristic of the power level transition is the transition profile.

7. The power transmitter according to claim 6, wherein, The adapter (211) is arranged to adapt the transition profile to have reduced higher frequency components as the level of the power level operating point increases.

8. The power transmitter according to any of the preceding claims, wherein, The power level transition is a transition from the lower power level to the higher power level.

9. The power transmitter according to any one of claims 1-7, wherein, The power level transition is a transition from the higher power level to the lower power level.

10. The power transmitter according to any of the preceding claims, wherein, The adapter (211) is arranged to determine the power level operating point based on the power supply characteristics of at least the output circuit of the driver (201).

11. The power transmitter according to any of the preceding claims, wherein, The adapter (211) is arranged to set the power level transition as a step transition in response to determining that the value of the power level operating point is less than a threshold.

12. The power transmitter according to any of the preceding claims, comprising a synchronizer (203) arranged to synchronize the communication time interval with a minimum value of a periodically varying power supply to at least the output circuit of the power transmission driver.

13. The power transmitter according to any of the preceding claims, wherein, The duration of the power level transition does not exceed 5 milliseconds.

14. The power transmitter according to any of the preceding claims, comprising a power control loop arranged to control the power level operating point in response to a power control message received from the power receiver (105).

15. A method of operating a power transmitter (101) for wirelessly supplying power to a power receiver (105) via an inductive power transmission signal, the method comprising: The power transmission coil (103) generates the power transmission signal; During the power transmission phase, a drive signal for the power transmission coil (103) is generated to employ a repetitive time frame, which includes at least a power transmission time interval and a communication time interval. The communication coil (207) generates a communication carrier signal during the communication time interval; During the communication time interval, communication is conducted with the power receiver (105) by modulating the communication carrier signal; The drive signal is controlled to perform a power level transition between a higher power level of the drive signal during a power transmission time interval and a lower power level of a communication time interval closest to the power transmission time interval, wherein the higher power level exceeds the lower power level by at least twice; as well as The characteristics of the power level transition are adapted to the power level operating point of the power transmission, wherein the characteristics of the power level transition are at least one of the following: The rate of change of the power level transition The duration of the power level transition, and The transition profile of the power level shift.

Images