Power transmission device and method

Abstract

A power transmission device serving as a power transmitter (101) or power receiver (103) for power transmission via a power transmission signal includes: a power coil (103, 107) for power transmission with a complementary power transmission coil (107, 103) of another device operating as a power transmission device; a first communicator (205, 305) for data communication with the complementary power transmission device by modulating the power transmission signal; a second communicator (207, 307) for communication of power transmission control data via a second communication channel independent of the power transmission signal and having a communication data rate at least ten times higher; a presence detector (209, 309) for determining, in response to the first data, whether the complementary power transmission device is present in the vicinity of the power transmission coil (103, 107); and a power transmission controller (201, 301) for limiting the wireless power transmission from the power transmitter (101) to the power receiver (103) in response to detecting the absence of the complementary power transmission device.

Description

Technical Field

[0001] The present invention relates to wireless power transmission devices and methods, and particularly, but not exclusively, to wireless power transmission devices for wireless power transmission systems (e.g., Qi-type power transmission systems) of the Wireless Power Consortium. Background Technology

[0002] Most electrical products today require dedicated electrical contacts to draw power from an external power source. However, this is often impractical and requires users to physically insert connectors or otherwise establish physical electrical contacts. Power requirements also vary considerably, and most devices are currently supplied with their own dedicated power supplies, resulting in a typical user having a large number of different power supplies, each dedicated to a specific device. While using an internal battery avoids wired connections to a power source during use, this only provides a partial solution, as the battery needs to be charged (or replaced). Using batteries also significantly increases the weight of the device, as well as potential cost and size.

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

[0004] Power transfer via magnetic induction is a well-known concept, primarily applied in transformers with tight coupling between the primary transmitter inductor / coil and the secondary receiver coil. Wireless power transfer between two devices can be achieved by separating the primary transmitter coil and the secondary receiver coil, based on the principle of a loosely coupled transformer.

[0005] This arrangement allows wireless power to be transmitted to the device without any wires or physical electrical connections. In practice, it simply allows the device to be placed near 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, allowing the device to be easily placed on that surface for power supply.

[0006] Furthermore, such wireless power transmission arrangements can be advantageously designed to allow power transmitter devices to be used with a range of power receiver devices. In particular, a wireless power transmission method known as the Qi specification has been defined and is currently under further development. This method allows Qi-compliant power transmitter devices to be used with Qi-compliant power receiver devices, without them having to be from the same manufacturer or be proprietary to each other. The Qi standard also includes features to allow operation to be tailored for specific power receiver devices (e.g., depending on specific power consumption).

[0007] The Qi specification was developed by the Wireless Power Consortium, and more information can be found, for example, on their website http: / / www.wirelesspowerconsortium.com / index.html, where, in particular, the specification document defining it can be found.

[0008] Further development aims to introduce a range of new applications and features. For example, the Wireless Power Consortium is developing a standard based on the Extended Qi principle for application in a range of kitchen applications and appliances, including heaters, kettles, blenders, and pans. This development specifically supports ultra-high power levels and is being called a cordless kitchen standard.

[0009] The Qi standard supports communication from a power receiver to a power transmitter, enabling the power receiver to provide information that allows the power transmitter to adapt to a specific power receiver. The current standard defines a unidirectional communication link from the power receiver to the power transmitter, where the power receiver communicates by performing load modulation on the power transmission signal. Specifically, the load adjustment of the power receiver on the power transmission signal provides modulation of the power signal. The power transmitter is able to detect and decode (demodulate) the resulting changes in electrical characteristics (e.g., changes in the current drawn).

[0010] Therefore, at the physical layer, the communication channel from the power receiver to the power transmitter uses a power transmission signal as the data carrier. The power receiver modulates the load detected by changes in the amplitude and / or phase of the transmitter coil current or voltage. Data is formatted in bytes and packets.

[0011] More information can be found in Chapter 6 of Part 1 of the Qi Wireless Charging Specification (Version 1.0).

[0012] Initially, Qi used only a unidirectional communication link, but bidirectional communication links have also been introduced to allow for more advanced and flexible control over power transmission operations. For example, communication from the power transmitter to the power receiver can be achieved by modulating the power transmission signal (e.g., using amplitude, frequency, or phase modulation).

[0013] However, it has been found that communication using power transmission signals is not always optimal. Specifically, the communication capacity and possible data rate of communication using power transmission signals as a carrier are often very limited and are typically restricted to a few hundred bits per second. As the power level increases, the suitability of power transmission signals for communication tends to decrease significantly.

[0014] Numerous wireless power transfer systems have been proposed for higher power levels. For example, the Wireless Power Consortium is developing a standard based on the Extended Qi principle for application in a range of kitchen applications and appliances, including heaters, kettles, blenders, and pans. This development specifically supports ultra-high power levels and is being touted as a cordless kitchen standard.

[0015] In most such high-power-level power transmission systems, it has been proposed to use a separate communication system that is independent of the power transmission signal and therefore does not specifically use the power transmission signal as a carrier for the communication link.

[0016] Such a standalone communication system typically offers significantly higher data rates and often provides more reliable communication. This allows for improved and more reliable power delivery in most practical applications.

[0017] However, while using a separate communication system can provide many advantages, the inventors have recognized that in some scenarios, the operation caused by a separate communication system may be suboptimal, and in particular, in some scenarios, a separate communication system may cause potential erroneous situations when the power receiver is moved, removed, or replaced.

[0018] Therefore, improved power transfer methods will be advantageous, especially those that allow for increased flexibility, reduced costs, reduced complexity, improved user experience, additional or improved functionality or services, improved operational reliability, improved error detection, and / or improved performance. Summary of the Invention

[0019] Therefore, the present invention seeks to mitigate, alleviate, or eliminate one or more of the aforementioned disadvantages, preferably in a single manner or in any combination thereof.

[0020] According to one aspect of the present invention, a power transmission device is provided for wireless power transmission from a power transmitter to a power receiver, the power transmission device being one of the power transmitter and the power receiver, the power transmission device comprising: a power transmission coil for transmitting power to a complementary power transmission coil of a complementary power transmission device via a power transmission signal, the complementary power transmission device being the other of the power transmitter and the power receiver; a first communicator for communicating first data with the complementary power transmission device via a first communication channel by modulating the power transmission signal during power transmission; and a second communicator for communicating power transmission control data with the complementary power transmission device via a second communication channel independent of the power transmission signal during power transmission, wherein, for the... The communication data rate of the second communication channel is not less than ten times the communication data rate for the first communication channel; a presence detector is used to determine, in response to the first data during power transmission, whether the complementary power transmission device is present near the power transmission coil; and a power transmission controller is arranged to limit the wireless power transmission from the power transmitter to the power receiver in response to detecting the absence of the complementary power transmission device; wherein the power transmission signal employs a repetitive time frame during power transmission that includes at least a power transmission time interval and a reduced power time interval, the power level of the power transmission signal being reduced during the reduced power time interval relative to the power transmission time interval; and wherein the first communicator is arranged to communicate the first data during the reduced power time interval.

[0021] This invention can provide improved performance and / or operation in many wireless power transfer systems. It can provide improved operation, including effective control over power transfer operations and mitigation or reduction of the risk of unwanted or undetected error scenarios (e.g., in the event of power receiver removal).

[0022] An presence detector can be arranged to determine, in response to first data, whether a complementary power transfer device is present near the power transfer coil; and can be specifically arranged to determine whether a power receiver that was present during the initialization of the power transfer is no longer present.

[0023] The first and / or second communication channel can be a bidirectional or unidirectional communication channel. The communication channel can be a communication link. Specifically, the communication data rate can be the maximum communication data rate or the communication capacity of the communication link. The communication data rate can be the average communication rate. For example, if the communication channel implements time-slotted operation, the communication data rate can be the averaged communication data rate across all time slots (including time slots where no data communication is performed).

[0024] Proximity is not necessarily a specific or well-defined proximity; that is, it does not typically correspond to a specific, well-defined predetermined distance. Instead, the power transmission device and the complementary power transmission device can be considered close if the first data satisfies a proximity criterion. The proximity criterion can be one that is satisfied for smaller distances between the power transmission device and the complementary power transmission device but not for larger distances (wherein the threshold is not necessarily specific or known). In many embodiments and scenarios, devices are considered close if they are located at a distance less than the communication range of the first communication link.

[0025] This operation can be performed during the power transfer phase, specifically the communication of initial data and power transfer control data, as well as presence detection. The power transfer phase can specifically be the phase of generating a power transfer signal for transferring power from the power transmitter to the power receiver. The power transfer phase can also be the phase where a power control error message is sent from the power receiver to the power transmitter. The power transmitter and power receiver can implement a power control loop for power transfer during the power transfer phase. The power control loop can adapt the level of the power transfer signal in response to a power control error message.

[0026] According to an optional feature of the invention, the communication data rate of the first communication channel does not exceed 500 bits per second.

[0027] This can provide particularly advantageous performance in many embodiments and scenarios. In many embodiments, it can allow for higher power levels of power transmission and / or allow for relatively low frequency power transmission signals.

[0028] According to an optional feature of the invention, the communication data rate of the first communication channel does not exceed 100 bits per second.

[0029] This can provide particularly advantageous performance in many embodiments and scenarios. In many embodiments, it can allow for higher power levels of power transmission and / or allow for relatively low frequency power transmission signals.

[0030] According to an optional feature of the invention, the first data is received from the complementary power transmission device, and the presence detector is arranged to determine that the complementary power transmission device does not exist in response to detecting that the first data satisfying the criterion has not been received.

[0031] This can provide particularly effective and advantageous operation in many embodiments. It can typically provide low-complexity but highly reliable detection of the presence of a power receiver within a power transmission domain suitable for use with a power transmitter.

[0032] Specifically, this criterion may involve receiving a given data pattern within a given time interval. This data pattern may be static, potentially predetermined, or dynamic.

[0033] According to an optional feature of the invention, the first data includes an identity indication for the complementary power transmission device, and the proximity detector is arranged to detect the absence of the complementary power transmission device in response to the absence of an identity indication that meets the criteria.

[0034] This can provide particularly effective and advantageous operation in many embodiments. Specifically, the criterion may be to receive a given identity data pattern within a given time interval. This data pattern may be static, potentially predetermined, or dynamic.

[0035] According to an optional feature of the invention, the first communicator is arranged to send a query message to the complementary power transmission device, and the proximity detector is arranged to detect the absence of the complementary power transmission device in response to the absence of first data including a valid response to the query message.

[0036] This can provide particularly effective and advantageous operation in many embodiments.

[0037] According to an optional feature of the invention, the first data includes control data for the power transmission.

[0038] This can provide particularly effective and advantageous operation in many embodiments, and can particularly provide improved control data communication.

[0039] According to an optional feature of the invention, the power transmission device further includes a power controller arranged to communicate control data for the power transmission with the complementary power transmission device, the power controller being arranged to communicate some control data with the complementary power transmission device via a first communication channel and to communicate other control data with the complementary power transmission device via a second communication channel.

[0040] This can provide particularly efficient and advantageous operation in many embodiments, and can particularly provide improved control data communication. The method can, for example, provide both high data rate control data communication and low latency control data communication by utilizing the different properties of different communication links. Control data used for power transmission with complementary power transmission devices can include control data affecting dynamic properties of power transmission (e.g., properties of the power transmission signal). These properties can be the level, duration, amplitude, intensity, and / or frequency of the power transmission signal.

[0041] The power transmission signal employs a repetitive time period comprising at least a power transmission time interval and a reduced power time interval, wherein the power level of the power transmission signal is reduced during the reduced power time interval relative to the power transmission time interval; and wherein the first communicator (205, 305) is arranged to communicate the first data during the reduced power time interval.

[0042] This can provide particularly efficient and advantageous operation in many embodiments. The power transmission signal can employ repeating time periods during the power transmission phase.

[0043] According to an optional feature of the invention, the power transmission signal has a fixed non-zero amplitude in a plurality of subsequent decreasing power time intervals.

[0044] This can provide particularly effective and advantageous operation in many embodiments.

[0045] According to an optional feature of the invention, the frequency of the power transmission signal during the reduced power time interval is higher than that during the power transmission time interval.

[0046] This can provide particularly effective and advantageous operation in many embodiments.

[0047] According to an optional feature of the invention, the power transmission device is the power receiver, and the complementary power transmission device is the power transmitter.

[0048] According to an optional feature of the invention, the power transmission device is the power transmitter, and the complementary power transmission device is the power receiver.

[0049] According to optional features of the present invention, a method of operating a power transmission device for wireless power transmission from a power transmitter to a power receiver, the power transmission device being one of the power transmitter and the power receiver, the method comprising: power transmission by a power transmission coil to a complementary power transmission coil of a complementary power transmission device, the complementary power transmission device being the other of the power transmitter and the power receiver, via a power transmission signal; communication of first data with the complementary power transmission device via a first communication channel by modulating the power transmission signal during power transmission; and communication of power transmission control data with the complementary power transmission device via a second communication channel independent of the power transmission signal during power transmission, wherein... The communication data rate for the second communication channel is not less than ten times the communication data rate for the first communication channel; during power transmission, in response to the first data, it is determined whether the complementary power transmission device is present near the power transmission coil; and in response to detecting the absence of the complementary power transmission device, the wireless power transmission from the power transmitter to the power receiver is limited; wherein the power transmission signal employs a repetitive time frame during power transmission that includes at least a power transmission time interval and a reduced power time interval, the power level of the power transmission signal being reduced during the reduced power time interval relative to the power transmission time interval; and wherein the communication of the first data occurs during the reduced power time interval.

[0050] According to one aspect of the present invention, a power transmission system for wireless power transmission from a power transmitter to a power receiver, the power transmitter comprising: a power transmitter coil for generating a power transmission signal for transmitting power to the power receiver; a first transmitter communicator for communicating first data with the power receiver via a first communication channel during power transmission by modulating the power transmission signal; and a second transmitter communicator for communicating power transmission control data with a complementary power transmission device via a second communication channel independent of the power transmission signal during power transmission, wherein the communication data rate for the second communication channel is not less than ten times the communication data rate for the first communication channel; and the power receiver comprising: a power receiver coil for receiving power via the power transmission signal; a first receiver communicator for communicating the first data with the power receiver via the first communication channel during power transmission; and a second receiver communicator for communicating power transmission control data via a second communication channel independent of the power transmission signal during power transmission. The second communication channel is used to communicate the power transmission control data with the power transmitter; wherein at least one of the power transmitter and the power receiver further includes: a presence detector, configured to determine, in response to the first data, during power transmission that the complementary power transmission device is present near the power transmission coil, the complementary power transmission device being another of the power transmitter and the power receiver, different from the at least one; and a power transmission controller, configured to limit the wireless power transmission from the power transmitter to the power receiver in response to detecting the absence of the complementary power transmission device; wherein the power transmission signal employs a repetitive time frame during power transmission that includes at least a power transmission time interval and a reduced power time interval, the power level of the power transmission signal being reduced during the reduced power time interval relative to the power transmission time interval; and wherein the first transmitter communicator and the first receiver communicator are configured to communicate the first data during the reduced power time interval.

[0051] These and other aspects, features, and advantages of the invention will become apparent and will be elucidated with reference to one or more embodiments described below. Attached Figure Description

[0052] Embodiments of the invention will be described with reference to the accompanying drawings, and by way of example only, in which:

[0053] Figure 1 Examples of elements of a power transmission system according to some embodiments of the present invention are illustrated;

[0054] Figure 2Examples of elements of a power transmitter according to some embodiments of the present invention are illustrated;

[0055] Figure 3 Examples of elements of a power receiver according to some embodiments of the present invention are illustrated; and

[0056] Figure 4 Examples of elements of a device according to some embodiments of the present invention are illustrated. Detailed Implementation

[0057] The following description focuses on embodiments of the invention applicable to wireless power transmission systems utilizing power transmission methods known, for example, according to the Qi specification. However, it should be understood that the invention is not limited to this application, but can be applied to many other wireless power transmission systems.

[0058] Figure 1 An example of a power delivery system according to some embodiments of the present invention is illustrated. The power delivery system includes a power transmitter 101 that includes (or is coupled to) a transmitter coil / inductor 103. The system also includes a power receiver 105 that includes (or is coupled to) a receiver coil / inductor 107.

[0059] This system provides wireless inductive power transfer from a power transmitter 101 to a power receiver 105. Specifically, the power transmitter 101 generates a wireless inductive power transfer signal (also referred to as a power transfer signal or inductive power transfer signal), which is propagated as a magnetic flux by a transmitter coil or inductor 103. The power transfer signal can typically have a frequency between about 20 kHz and about 500 kHz, and for Qi-compatible systems it is typically in the range of 95 kHz to 205 kHz (or, for example, for high-power kitchen applications, the frequency can typically be in the range of 20 kHz to 80 kHz). The transmitter coil 103 and the receiver coil 107 are loosely coupled, so that the receiver coil 107 picks up (at least a portion) of the power transfer signal from the power transmitter 101. Therefore, power is transferred from the power transmitter 101 to the power receiver 105 via wireless inductive coupling from the transmitter coil 103 to the receiver coil 107. The term power transfer signal is primarily used to refer to the induced signal / magnetic field (magnetic flux signal) between the transmitter coil 103 and the receiver coil 107. However, it should be understood that, equivalently, the power transfer signal can also be considered and used as a reference for the electrical signal provided to the transmitter coil 103 or picked up by the receiver coil 107.

[0060] In this example, specifically, the power receiver 105 is a power receiver that receives power via a receiver coil 107. However, in other embodiments, the power receiver 105 may include a metallic element, such as a metallic heating element, in which case the power transmission signal induces eddy currents, thereby causing the element to heat up directly.

[0061] The system is configured to transmit substantial power levels, and in particular, in many embodiments, the power transmitter can support power levels exceeding 500mW, 1W, 5W, 50W, 100W, or 500W. For example, for Qi-compliant applications, power transmission is typically in the 1-5W range for low-power applications, while for high-power applications supported by the Cordless Kitchen standard developed by the Wireless Power Consortium, power transmission exceeds 100W and can reach up to 1000W.

[0062] In the following description, the operation of the power transmitter 101 and the power receiver 105 will be described with specific reference to embodiments of the Qi specification (other than the modifications and enhancements described herein or consequential) or suitable for higher power cordless kitchen specifications.

[0063] Figure 1 The system utilizes bidirectional communication to support power transfer operations. Bidirectional communication is used to configure, establish, and control power transfer and can include the exchange of a range of control data. In particular, the communication channel between the wireless power transmitter and the wireless power receiver is considered essential for establishing a feedback loop from the wireless power receiver to the wireless power transmitter, which is crucial for the stability of the power system.

[0064] For example, the current Qi specification limits wireless power transmission to 15 watts. Such a power level might be considered a low-power wireless system. This type of system uses modulation of the power transmitter as the means of communication between the transmitter and receiver. This is also known as in-band communication.

[0065] However, such communication is not ideal for all systems, and is often suboptimal, especially for higher power levels. Specifically, for applications with high transmission power levels, modulation of the power transmission signal creates additional sources of loss, and the absolute value of the loss increases with the power level. These losses lead to heat dissipation, for example, in the power electronics of the wireless power system, or in the materials within the operating range of the wireless power system.

[0066] Furthermore, to provide effective control over power transmission, a high communication data rate between the power transmitter and the power receiver is desirable. However, using the power transmission signal as the carrier signal often makes it difficult to achieve this expectation, especially for higher-power applications (e.g., kitchen applications), where the achievable data rate is typically too low to support the desired functionality. Specifically, when the operating frequency of the power transmission signal is on the order of 20 to 300 kHz, the channel bandwidth is often insufficient for more complex operations (e.g., operations for power receiver licensing).

[0067] Therefore, higher-power systems (e.g., those compatible with cordless kitchen specifications) often replace in-band communication using power-transmitted signals with out-of-band communication channels implemented by a separate, typically dedicated, short-range communication system. This separate communication system is independent of the power-transmitted signal and does not use the power-transmitted signal as a carrier for communication. It is often a short-range communication system (e.g., Bluetooth or NFC communication systems).

[0068] However, the inventors have recognized that there are specific drawbacks associated with such a method, and that these drawbacks can be mitigated by... Figure 1 The system has been effectively resolved. Figure 1 The system implements two communication channels between the power transmitter and the power receiver. Specifically, a low-data-rate communication link is established using the power transmission signal as a carrier, and a higher-data-rate communication link is established using a separate communication system. The inventors have particularly recognized that proximity detection can be implemented based on the low-data-rate communication channel using the power transmission signal, thereby allowing for more reliable and robust operation, which in particular reduces the risk of generating strong magnetic fields in the presence (or erroneous) power receiver.

[0069] Specifically, wireless power transfer occurs in the system when the power receiver coil is close to the wireless power transmitter coil and these coils have a sufficient coupling factor to efficiently transfer energy. This proximity zone is typically defined as the combination of the misalignment between the wireless power receiver and transmitter coils and the maximum vertical distance between them. This volume is considered the wireless power operating zone / volume of the wireless power system.

[0070] The inventors have recognized that when using established out-of-band communication channels for wireless power transmission, the communication link typically has a range that differs from the wireless power operating area / volume, and this can cause problems that conventional in-band communication methods can inherently avoid.

[0071] exist Figure 1The system employs a parallel dual-communication system. One communication link / channel is an out-of-band communication link independent of the power transmission signal, while the other is an in-band communication link that uses the power transmission signal as a carrier for data modulation. The in-band communication link is implemented using a low data rate, while the out-of-band communication link is implemented using a high data rate. The data rate of the out-of-band communication link is no less than ten times that of the in-band communication link.

[0072] Out-of-band communication links are used for communication of control data, which can specifically be control data supporting power transfer signals, such as power control messages. Therefore, power transfer operations can be based on the exchange of large amounts of data / information.

[0073] The in-band communication link is used to provide proximity detection for the system, to detect whether the power transmitter and power receiver are indeed close to / remain close together. Therefore, the in-band communication link can be used to detect situations where the power receiver and / or power transmitter are moved so that they are no longer close to each other, and in response, the system can continue, for example, terminating power transmission.

[0074] This method reflects the inventors' understanding that it is important to detect when the wireless power receiver is located within the wireless power operating area / volume. Once the wireless power receiver leaves the wireless power operating volume, wireless power transmission should be interrupted (e.g., stopped or reduced to a low level) to ensure that the large magnetic field from the wireless power transmitter does not have any negative impact on other devices (e.g., this could cause undesirable heating of metallic objects or potentially damage other electrical equipment, especially when different power receivers are close to the power transmitter).

[0075] To address this issue, the system may include proximity / presence detection technology, which seeks to establish a clear one-to-one relationship between the wireless power receiver and the wireless power transmitter in power transmission. In this context, proximity / presence detection is considered the ability of the wireless power transmitter to detect / estimate whether an associated wireless power receiver is present or absent within its operating volume.

[0076] In systems where communication is based on the modulation of the power transmission signal (e.g., the Qi system), this can inherently occur because removing the power receiver from the power operation would cause communication failure, resulting in the termination of power transmission.

[0077] However, in the case of wireless power transmission over an established out-of-band communication link (where the range of the communication link is larger than the corresponding wireless power operating volume), power transmission can continue because valid control data may still be exchanged. Figure 1The system can address this scenario because it includes presence / proximity detection functionality to detect when a (suitable) power receiver is located within a suitable wireless power operating volume for the power transmitter. Furthermore, this presence / proximity detection is based on supplementing an out-of-band communication link with an in-band communication link specifically designed for performing presence detection. Specifically, a high-data-rate out-of-band communication link can be used to transmit control data at a high data rate to efficiently support power transmission, and this can be supplemented by the in-band communication link by transmitting presence data used to perform presence detection. In particular, if the correct presence data is successfully transmitted, it can be determined that the power transmitter and power receiver are close, and if the presence data is not successfully transmitted, it can be determined that the power transmitter and power receiver are not close enough for the presence to be detected. The presence data can typically be any data suitable for detecting the presence of a power receiver (or vice versa) near the power transmitter.

[0078] The described method therefore implements proximity detection of the wireless power receiver during wireless power transmission (and particularly during the power transmission phase). This method can, for example, enable the power transmitter to detect the proximity of the power receiver and terminate power transmission if the power receiver has been detected to have left the wireless power operating volume. For example, if proximity detection fails during the power transmission phase, the system can terminate power transmission. Presence / proximity detection can be based on the fact that the system utilizes the power transmission signal as a communication carrier for modulation by presence data. This can particularly tightly link presence / proximity detection with power transmission operation, resulting in more robust operation. Detection of the power receiver's absence can particularly cause the termination of power transmission / power transmission phase to avoid undesirable operational scenarios, and particularly to avoid generating such undesirable strong electromagnetic fields when they are not required as part of effective power transmission.

[0079] Reference Figure 2 To describe this method in more detail, Figure 2 The components of the power transmitter 101 are illustrated, and Figure 3 A more detailed illustration is provided. Figure 1 The power receiver 105 is a component.

[0080] Figure 2 A more detailed illustration is provided. Figure 1Example of components for a power transmitter 101. A transmitter coil 103 is coupled to a driver 201, which generates a drive signal for the transmitter coil 103. The driver 201 generates current and voltage signals, which are fed to the transmitter inductor 103. The driver 201 is typically a drive circuit in the form of an inverter that generates an AC signal based on a DC voltage. The output of the driver 201 is typically a switching bridge, thereby generating the drive signal by appropriately switching the switches of the switching bridge.

[0081] The driver 201 is coupled to a power transmitter controller 203, which is arranged to control the operation of the power transmitter 101. The power transmitter controller 203 may be arranged to control the operation of the power transmitter 101 to perform required and desired functions associated with the power transmission protocol of the system, and in this example, may be specifically arranged to control the power transmitter 101 to operate according to the cordless kitchen specification. For example, the power transmitter controller 203 may include functions for: detecting the power receiver, initiating power transmission, supporting power transmission, terminating power transmission, etc.

[0082] In this example, the power transmitter 101 also includes a first transmitter communicator 205, which is arranged to communicate with the power receiver 105. The first transmitter communicator 205 is arranged to use a power transmission signal as a communication carrier to communicate with the power receiver 105; that is, the first transmitter communicator 205 can modulate data onto the power transmission signal. The first transmitter communicator 205 is arranged to communicate with the power receiver 105 using an in-band communication link.

[0083] The power transmitter communicator 205 can typically be arranged to receive messages from the power receiver 105 via a load modulated power transmission signal, the operation of which can be known by a person skilled in the art, for example, according to the Qi transmission specification. The power transmitter communicator 205 can (e.g., by modulating the power transmission signal) transmit messages to the power receiver. For example, the first transmitter communicator 205 can control a driver to change the frequency, amplitude, and / or phase of a drive signal in response to data to be transmitted. Therefore, the power transmitter controller 203 can use, for example, frequency, amplitude, and / or phase modulation to transmit data to the power receiver 105. In many embodiments, the first transmitter communicator 205 can support bidirectional communication; however, it will be appreciated that in some embodiments, communication may be unidirectional.

[0084] The power transmitter 101 also includes a second transmitter communicator 207, which is arranged to communicate with the power receiver 105 in a manner independent of the power transmission signal. The second transmitter communicator 207 is arranged to communicate with the power receiver 105 using a communication link that uses a different communication carrier than the power transmission signal. Therefore, the second transmitter communicator 207 establishes an out-of-band communication link independent of the power transmission signal, and data transmitted via this link is not modulated onto the power transmission signal.

[0085] In different embodiments, the exact communication method and communication carrier used can be different and can depend on the preferences and requirements of a specific application. Out-of-band communication links are typically implemented by short-range communication systems; however, these short-range communication systems have a range significantly greater than the power transmission range and significantly exceed the operational volume of wireless power transmission.

[0086] In many embodiments, the in-band communication link can be implemented by a standardized short-range communication system such as Bluetooth or NFC. Such a communication system can provide an efficient out-of-band communication link, thereby providing high data rates, reliable communication, and generally low-cost implementation. In particular, such a communication system can provide efficient control data exchange for power transmission. In many embodiments, the second transmitter communicator 207 can support bidirectional communication; however, it will be appreciated that in some embodiments, communication can be conducted in only one direction.

[0087] like Figure 3 As shown, the receiver coil 107 of the power receiver 105 is coupled to a power receiver controller 301, which couples the receiver coil 107 to a load 303. The power receiver controller 301 includes a power control path that converts the power extracted by the receiver coil 107 into a power supply suitable for supplying power to the load 303. Additionally, the power receiver controller 301 may include various power receiver controller functions required to perform power transfer, and particularly those required to perform power transfer according to cordless kitchen specifications.

[0088] The power receiver 105 also includes a first receiver communicator 305, which is configured to communicate with the first transmitter communicator 205 using a power transmission signal as a carrier. Therefore, the first transmitter communicator 205 and the first receiver communicator 305 establish an in-band communication link.

[0089] In-band communication links typically have very low data rates. This system is particularly well-suited for wireless power transmission at high power levels (e.g., above 100W). Due to the extremely high power levels, communication using power transmission signals as the communication carrier becomes very difficult, and a relatively low data rate must be maintained to ensure reliable communication and minimize the impact on power transmission.

[0090] In most embodiments, the communication data rate for communication on the in-band communication link does not exceed 1000 bits / second, 500 bits / second, or even 100 bits / second. This is generally suitable for high-power transmission and providing a reliable communication link.

[0091] However, in most embodiments, this is insufficient to achieve optimized power delivery control. For example, it is desirable to transmit control data at a higher data rate. For instance, power control data, such as power control loop error messages, may be transmitted, which may indicate, for example, an absolute error (a mismatch between the expected power / current levels on the receiver side) or a relative error (the receiver only reports this when it needs more or less power).

[0092] To support this high data rate communication, the power receiver 105 also includes a second receiver communicator 307, which establishes an out-of-band communication link with the second transmitter communicator 207. The secondary resonant circuit 205 can therefore complement the first transmitter communicator 205.

[0093] Therefore, the power transmitter 101 and the power receiver 105 can establish two communication links simultaneously during power transmission operation, each of which can be unidirectional (in either direction) or bidirectional.

[0094] Two communication links typically have very different properties. In particular, the data rate of an out-of-band communication link is at least ten times that of an in-band communication link. Therefore, the communication rate of an out-of-band communication link is much greater than that of an in-band communication link. However, these communications may also differ in other parameters, such as communication reliability and error rate.

[0095] Furthermore, the ranges of the two communication links are typically different, or at least known to be not exactly the same. In most embodiments, the out-of-band communication link will have a longer (significantly longer) range than the in-band communication link. Additionally, due to the fact that the in-band communication link uses power transmission signals as the communication carrier, the range of the in-band communication link contrasts with that of the out-of-band communication link, which is inherently linked to the range of power transmission.

[0096] In this system, this is used to provide proximity / presence detection during the power transfer phase.

[0097] As a specific example, the power transmitter 101 includes a transmitter presence detector 209, which is arranged to determine the presence of a power receiver in the vicinity of the transmitter coil 103 based on data transmitted via an in-band communication link.

[0098] In some embodiments, the first transmitter communicator 205 may be arranged to receive data from the power receiver 105, and the first transmitter communicator 205 may be arranged to determine that the power receiver 105 does not exist (is not present) in response to detecting that data that has not yet been received / has not met a given criterion has not been received.

[0099] In many embodiments, the criterion can simply be the receipt of a given data pattern. For example, transmitter presence detector 209 can receive data to be compared with a predetermined pattern, and if the data matches the predetermined pattern (according to a given matching criterion), it is determined that a power receiver is still present. If no data matching the predetermined pattern is received within a given time limit, transmitter presence detector 209 can determine that the power receiver is no longer present within the operating volume of the power transmission.

[0100] To support such operation, the power receiver can transmit a desired predetermined pattern at regular intervals (and possibly continuously). For example, a continuous feedback system can be generated, in which the power receiver continuously transmits data and the power transmitter continuously evaluates whether such data has been successfully received. If this communication feedback loop is active, it necessarily means that the power receiver is close enough to allow reliable communication using the power transmission signal, and therefore the power receiver is considered to be present in the power transmission operating volume (i.e., the power receiver is considered sufficiently close / near). Thus, the method can continuously determine whether the power receiver is present within the proximity of the transmitter coil 103 corresponding to the communication range of the in-band communication link. When the in-band communication link is based on using the power transmission signal as the communication carrier, the communication range of the in-band communication link is inherently associated with the power transmission range, therefore the method provides a good estimate / detection of whether the power receiver is present within the power transmission operating volume.

[0101] A transmitter presence detector 209 is coupled to a power transmitter controller 203, which is configured to limit power transmission in response to the detection of the absence of a complementary device. Therefore, the transmitter presence detector 209 continuously sends the results of the detection process to the power transmitter controller 203, and can continue to limit power transmission if it indicates that the power receiver is not (or may not be) in the operating volume. This limitation can typically be a maximum power level limit applied to the power transmission signal, where the maximum power level is lower than the maximum power level limit for power transmission (when no limit is applied).

[0102] Typically, the power transmitter controller 203 is configured to terminate power transmission in response to the detection of the absence of a power receiver (equivalent to limiting power transmission or the maximum power level limit to zero). Therefore, if power transmission is in progress (the system is operating in a power transmission phase) and the power transmission device (e.g., by determining that the expected data has not been received on the in-band communication link) detects the absence of a power receiver, it notifies the power transmitter controller 203, and the power transmitter controller 203 terminates power transmission, thereby preventing the generation of a strong magnetic signal in the absence of a power receiver.

[0103] The above description focuses on a scenario where a power transmitter detects the presence of a power receiver and controls power transmission accordingly. However, it will be appreciated that in other embodiments, the detection function may alternatively or additionally reside in the power receiver. In fact, all comments provided above and below regarding systems where the detection function is located in the power transmitter can also be considered applicable to complementary scenarios where the detection function is located in the power receiver (e.g., referring to a power transmitter that detects whether a power receiver is nearby, this situation can be appropriately modified for a power receiver that detects whether a power transmitter is nearby).

[0104] Specifically, the power receiver 105 may include a receiver presence detector 309, which is arranged to determine the presence of the power transmitter 101 in the vicinity of the transmitter coil 103 based on data transmitted via an in-band communication link.

[0105] In some embodiments, the first receiver communicator 305 may be arranged to receive data from the power transmitter 101, and the first receiver communicator 305 may be arranged to determine that the power transmitter 101 does not exist in response to detecting that no presence data satisfying a given criterion has been received.

[0106] As described for complementary scenarios, the criterion can simply be receiving a given data pattern. For example, the receiver presence detector 309 can receive data transmitted from the first transmitter communicator 205, obtained by, for example, AM, FM, or PM modulation of the power transmission signal, and this data can be compared with a predetermined pattern. If they match (according to a given matching criterion), it is determined that the power transmitter 101 still exists, and therefore reliable power transmission is feasible. If no data is received within a given threshold that matches the predetermined pattern, the receiver presence detector 309 can determine that the power transmitter 101 no longer exists within the operating volume of power transmission.

[0107] As described for complementary scenarios, the first transmitter communicator 205 can continuously transmit a predetermined pattern, and the receiver presence detector 309 can continuously monitor this predetermined pattern. Again, since communication is based on using a power transmission signal as a carrier, it is a good indicator of whether the power receiver and the power transmitter are close enough to consider the power receiver as being within the power transmission operating volume.

[0108] A receiver presence detector 309 is coupled to a power receiver controller 301 and notifies the power receiver controller 301 if (by not receiving suitable data) it detects that the power transmitter is no longer present near the receiver coil 107. The power receiver controller 301 can restrict power transfer operations. This can be done in different ways depending on the application, but in many embodiments, this is achieved by the power receiver 105 using an out-of-band communication link (which typically has a larger range than an in-band communication link) to transmit data requests or commands to the power transmitter.

[0109] Power receiver 105 can, for example, directly send a command to terminate power transmission or limit the power level to a given value. In other embodiments, power receiver controller 301 can modify the transmission of control data such that this causes a desired change in power transmission. For example, a continuous power-off request can be sent. As another example, power receiver controller 301 can refuse to send messages essential for continuing power transmission. For example, if an erroneous control message is not sent, power transmitter 101 will terminate power transmission.

[0110] Therefore, in general, the described functionality can be considered applicable to power transmission devices (as power transmitters or power receivers) used to perform power transmission with a complementary power transmission device (as the other of the power transmitter and power receiver). For the sake of brevity, this description focuses on the case where the power transmission device including the detection function is a power transmitter and the complementary device is a power receiver; however, it will be appreciated that the comments provided also apply to the case where the detection function is in the power receiver and the complementary device is a power transmitter. In fact, in many embodiments, the detection function can be implemented in both the power transmitter and the power receiver.

[0111] Therefore, the provided descriptions and individual comments (with appropriate modifications) also apply to complementary settings, i.e., by exchanging the features and references of the power receiver and power transmitter where appropriate.

[0112] In many embodiments, the data used for presence detection (hereinafter referred to as presence data) may specifically be an identity indication for a complementary device, i.e., an identity indication for either power transmitter 101 or power receiver 105 where appropriate. In some embodiments, the identity indication may be a predetermined identity. For example, a specific data pattern may be assigned to each device at manufacturing time, and this data pattern may be transmitted as preference data. In some embodiments, the presence detector may have predetermined knowledge of the identity data pattern (e.g., the power transmitter may be designed to work with a specific power receiver), but in most embodiments, the predetermined knowledge of the identity data pattern will be transmitted during the initialization of power transmission. For example, when power transmission is being initialized, the power receiver may send the identity data pattern (signature) to the power transmitter, and the transmitter presence detector 209 may check during power transmission whether it receives a data pattern from the power receiver that matches the signature sufficiently frequently. If this is not the case, the power transmitter will continue to terminate power transmission, whether the data pattern is not received or an incorrect data pattern is received. Therefore, if the power receiver is removed and quickly replaced by another power receiver, the transmitter presence detector 209 will detect this and power transmission will be terminated, even if the power transmitter is still able to receive valid control data from the previous power receiver via the out-of-band communication link.

[0113] Therefore, in many embodiments, the detection of the absence of complementary devices (in particular, the detection of the absence of power receivers by transmitter presence detector 209) is based on the detection that no identity indication satisfying a given criterion has been received (e.g., no expected data pattern has been received within a given time period).

[0114] In many embodiments, the identity indication can be a temporary identity and can be specifically designed for that particular power transfer operation. For example, during power transfer initialization, the power transmitter can assign and send a data signature (pattern) to the power receiver. The power receiver can then send the data signature at regular intervals during the power transfer operation, and the transmitter presence detector 209 will continue to monitor the data signatures and terminate the power transfer if the data signature is not received sufficiently frequently.

[0115] It will also be recognized that, in many embodiments, identity can be transmitted in both directions, and both devices can monitor to ensure that appropriate identity indication is received. Therefore, in many embodiments, an in-band communication link can be used to transmit identity data bidirectionally during power transmission, and the continuation of power transmission can depend on receiving correct identity data at both devices.

[0116] Specifically, before power transmission begins, the power transmitter and power receiver can exchange TXID and RXID. During power transmission, the power transmitter transmits the TXID via an in-band communication link, and the power receiver transmits the RXID via the same link. Then, if the wireless power transmitter identifies an incorrect (unauthorized) wireless power receiver (incorrect RXID) within the wireless power operating volume, or if no wireless power receiver is identified within the operating volume (no RXID), the wireless power transmitter will terminate power delivery. Similarly, if the power receiver identifies an incorrect wireless power transmitter within the operating volume (incorrect TXID), the power receiver can report this situation to the power transmitter used to initiate the power transmission, and the power transmitter will then terminate the power transmission.

[0117] It will be appreciated that different presence data and identity indicators may be used in different embodiments, including, for example, out-of-band communication link MAC address, CRC or other data sequences.

[0118] In some embodiments, data exchange can use a request and response format, whereby the message performing the detection can initiate and control communication. For example, the transmitter presence detector 209 can determine when it is time (e.g., at regular intervals) to perform a presence test, and the transmitter presence detector 209 can initiate a first transmitter communicator 205 to send a query message requesting a response to the power receiver. For example, a simple pattern corresponding to a request for the identity of the power receiver to be sent can be requested. In response, the power receiver can send a response message.

[0119] In such a scenario, if the transmitter presence detector 209 receives a valid response (e.g., a suitable identification indication) within a given duration, the transmitter presence detector 209 can determine that the power receiver still exists. However, if no acceptable response message is received, the transmitter presence detector 209 will determine that the power receiver is not present, and the transmitter presence detector 209 will control the power transmitter controller 203 to terminate power transmission.

[0120] The advantage of this method is that presence detection only needs to be performed in one device (usually the power transmitter), but presence is only detected if in-band communication between the power transmitter and the power receiver is possible in both directions.

[0121] In many embodiments, the out-of-band communication link can be used to transmit control data for power transmission as previously described, while the in-band communication link is used only to transmit data for presence detection (e.g., identification data only). However, in some embodiments, the system can be arranged to distribute control data communication on both the in-band and out-of-band communication links, so that both communication methods can be used for control data communication.

[0122] This can offer particular advantages in many scenarios. Specifically, out-of-band communication links can provide high maximum data rates, making them suitable for supporting control data with high data rates. However, while offering high data rates, many out-of-band communication links are often associated with higher communication latency compared to in-band communication links. In fact, in many embodiments, in-band communication links may be characterized by supporting lower data rates than out-of-band links, but still having significantly lower data rates. Therefore, in some embodiments, in-band communication links are specifically used for latency-sensitive control data, while out-of-band communication links are used for high data rate control data.

[0123] As an example, low-latency in-band communication links can be used for time-critical control data that instructs immediate actions requested by the power receiver, such as adjusting power to a negotiated level or immediately stopping power transmission. Out-of-band communication links may be used to negotiate precise power levels or absolute power mismatches, providing users with an interface to control power transmission or negotiating other auxiliary data not directly related to power transmission.

[0124] In many embodiments, presence detection can also be based on data that is control data transmitted on the in-band communication link. For example, if the transmitter presence detector 209 detects that valid power control messages are received sufficiently frequently on the in-band communication link, it can be assumed that the power receiver is indeed present. However, if the transmitter presence detector 209 detects that no power control messages are received, it can be assumed that the power receiver is not present.

[0125] In some embodiments, the power transmission signal undergoes a repetitive time period, which includes at least one power transmission time interval and a decreasing power time interval. The repetitive time period is applied to the power transmission signal during the power transmission phase.

[0126] During a decreasing power time interval relative to the power transmission time interval, the power level of the power transmission signal is reduced, and typically the maximum permissible power is not less than five, ten, or fifty times the power level during the decreasing power time interval (rather than during the power transmission time interval). This reduction in power level can be achieved by actions performed at the power transmitter and / or power receiver. For example, in some embodiments, the power transmitter may be arranged to cut off the power transmission signal during the decreasing power time interval, and / or the power receiver may be arranged to disconnect the load during the decreasing power time interval.

[0127] The power transmitter and / or power receiver are arranged to perform presence data communication during a decreasing power time interval. The presence data communication is in-band communication and uses a power-transmitted signal as the communication carrier. Therefore, during the decreasing power time interval, the power level of the power-transmitted signal is not set to zero, but rather to a lower value.

[0128] Typically, during the decreasing power time interval, the power level of the power transmission signal is further set to a constant fixed value. In some embodiments, the power level is set to a fixed, predetermined value during the decreasing power time interval, but in some embodiments, the power level can be adjusted. However, in most embodiments, such adjustment will be very slow, and the power level can be considered constant for at least some successive decreasing power time intervals.

[0129] Therefore, in multiple subsequent decreasing power time intervals, the power transfer signal is typically set to a fixed non-zero amplitude / power level. This power level is further reduced compared to a power level that can be applied outside the decreasing power time intervals, and in particular, the maximum power level can be reduced during the decreasing power time intervals relative to the power transfer signal.

[0130] Figure 4The illustration shows an example of operations using repeated time periods. Figure 4 The amplitude of the power transmission signal is shown during the decreasing power time interval 401 and during the power transmission interval 403. In Example A, the power level varies during the power transmission interval, while in Example B, the power level is constant during the power transmission time interval 403.

[0131] In many embodiments, the voltage supply provided to the driver / inverter 201 is generated directly from the mains voltage without any voltage regulation or smoothing (though some rectification may be present). Therefore, in practice, the voltage supply provided to the driver / inverter 201 can often be generated from a sinusoidal or rectified sinusoidal supply voltage. Typically, it has a relatively low frequency of 50Hz or 60Hz (twice that if rectification is applied), and the driver generates a higher frequency drive signal based on this supply voltage. The amplitude / power level of the higher frequency drive signal varies accordingly with the supply voltage signal, such as... Figure 4 As shown.

[0132] In such a case, the reduced power time interval can be synchronized with the change in power / amplitude level, and in particular, can be synchronized to occur near its minimum value (typically corresponding to a zero crossover of the supply voltage to the driver).

[0133] This can provide improved performance and can be specifically optimized for power transmission performance by minimizing the impact of introducing these reduced power time intervals on power transmission.

[0134] It should be noted that Figure 4 The power level during the power transmission interval is shown, and it is indicated that the power level is lower during the reduced power transmission interval in comparison. However, as mentioned earlier, the power transmission signal is not interrupted, and the power level is not set to zero. Instead, the power level is set to a lower, typically predetermined value.

[0135] Presence data is then transmitted during the reduced power time interval, thus transmitting presence data during a predetermined period when the power transmission signal can be set to a constant level. This ensures more reliable communication and reduces the impact of modulated power transmission signals on power transmission operation. Additionally, it allows for more reliable and robust operation and presence detection.

[0136] In practice, reducing the power level can reduce the communication range because the power of the communication carrier is correspondingly reduced. This ensures that the power receiver and power transmitter are close enough to ensure secure power transmission in cases where data can be successfully transmitted. In fact, the power level during the reduced power time interval can be specifically selected to provide the desired communication range for data in transit.

[0137] This method reflects the understanding that at higher power levels, in-band communication is unreliable or may lead to unacceptable power loss. For drivers based on AC trunk power supplies, modulation of the power carrier can be performed near trunk zero crossings where the transmitted power level is sufficiently low. During the power transmission / power delivery phase, the power transmitter can operate in two modes: trunk mode (high power delivery mode) and low power delivery mode, corresponding to the power transmission time interval and the reduced power time interval, respectively.

[0138] Specifically, the wireless power transmitter can periodically stop trunk power delivery within short time intervals (reduced power time intervals). During these time slots, the wireless power transmitter provides lower power to the wireless power receiver. During low-power carrier delivery, the wireless power transmitter and receiver are able to exchange data (e.g., RXID and / or TXID) by modulating the low-power carrier.

[0139] In some embodiments, the power transmitter 101 may be arranged to change not only the power level but also the frequency during the decreasing power time interval. Specifically, the power transmitter 101 may be arranged to increase the frequency of the power transmission signal such that the frequency during the decreasing power time interval is higher than the frequency during the power transmission time interval. For example, during power transmission, the frequency of the power transmission signal may be, for example, 100 kHz, but during the decreasing power time interval, the frequency of the power transmission signal may be increased to 150 kHz.

[0140] This higher frequency may not be ideal for power transmission, but it allows for improved communication. For example, it can allow for higher bandwidth, and therefore higher communication data rates. This can be particularly important for time-slotted operations, as communication may occur only during reduced power time intervals rather than throughout the entire duration. Therefore, during reduced power time intervals, the average communication rate can be significantly lower than the instantaneous data rate, making it important to maximize this.

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

[0142] Not every trunk power signal time slot can be used for proximity tracking. The given solution opens up the possibility of using only some time slots (e.g., every other power time slot) to deliver low power and detect proximity, while other time slots may be used for foreign object detection or other purposes. The size of the trunk power time slot to be interrupted and the interval between two time slots may be static values ​​pre-programmed by the wireless power transmitter, pre-programmed static values ​​in the wireless power receiver, or values ​​negotiated between the wireless power receiver and the wireless power transmitter via a communication channel. A trade-off must be considered between time slot size, time slot frequency, and trunk power interruption—too long intervals between time slots increase risk, while the time slot size should at least be sufficient for some form of communication using a low-power carrier. For wireless power systems utilizing AC power transmission, interrupting power delivery near the zero-crossing point of the AC trunk does indeed make sense in terms of reducing power loss. Figure 4 The timeline shows alternating trunk power delivery and low power delivery for both AC and DC trunk scenarios.

[0143] To keep the time slot size short, IDs can be sent over several time slots. This increases system response time, but reduces the power level transmitted in AC trunk conditions and reduces the power gap in DC conditions.

[0144] The invention can be implemented 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.

[0145] 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 claims. Furthermore, although it appears 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 "comprising" does not exclude the presence of other elements or steps.

[0146] Furthermore, although listed separately, multiple units, elements, circuits, or method steps can be implemented, for example, by a single circuit, unit, or processor. Additionally, while individual features may be included in different claims, these features may also be advantageously combined, and the inclusion of these features in different claims does not imply that the combination of features is infeasible and / or disadvantageous. Moreover, including a feature in a claim of one type does not imply a limitation on that type, but rather indicates that the feature can be equally applied to other claim types where appropriate. Furthermore, the order of features in a claim does not imply a specific order in which the features must operate, and in particular, the order of individual 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. Additionally, 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 only as illustrative examples and should in no way be construed as limiting the scope of the claims.

Claims

1. A power transmission device for wireless power transmission from a power transmitter (101) to a power receiver (105), the power transmission device being one of the power transmitter and the power receiver, the power transmission device comprising: Power transmission coils (103, 107) are used for power transmission via a power transmission signal to complementary power transmission coils (107, 103) of a complementary power transmission device, which is another of the power transmitter (101) and the power receiver (105). A first communicator (205, 305) is used to communicate first data with the complementary power transmission device via a first communication channel during power transmission by modulating the power transmission signal. The second communicator (207, 307) is used to communicate power transmission control data with the complementary power transmission device via a second communication channel independent of the power transmission signal during power transmission, wherein the communication data rate for the second communication channel is not less than ten times the communication data rate for the first communication channel. Presence detectors (209, 309) are used to determine, in response to the first data, during power transfer to, the presence of the complementary power transfer device in the vicinity of the power transfer coils (103, 107); and A power transmission controller (201, 301) is arranged to limit the wireless power transmission from the power transmitter (101) to the power receiver (105) in response to the detection that the complementary power transmission device is not present; The power transmission signal employs a repetitive time frame during power transmission that includes at least a power transmission time interval and a reduced power time interval, wherein the power level of the power transmission signal is reduced during the reduced power time interval relative to the power transmission time interval; and wherein the first communicator (205, 305) is arranged to communicate the first data during the reduced power time interval.

2. The power transmission device as claimed in claim 1, wherein, The communication data rate of the first communication channel does not exceed 500 bits per second.

3. The power transmission device as claimed in claim 1, wherein, The communication data rate of the first communication channel does not exceed 100 bits per second.

4. The power transmission device according to any one of claims 1-3, wherein, The first data is received from the complementary power transmission device, and the presence detectors (209, 309) are arranged to determine that the complementary power transmission device does not exist in response to detecting that the first data satisfying the criteria has not been received.

5. The power transmission device according to any one of claims 1-3, wherein, The first data includes an identity indication for the complementary power transmission device, and the presence detectors (209, 309) are arranged to detect the absence of the complementary power transmission device in response to the absence of an identity indication that meets the criteria.

6. The power transmission device according to any one of claims 1-3, wherein, The first communicator (205, 305) is arranged to send a query message to the complementary power transmission device, and the presence detector (209, 309) is arranged to detect the absence of the complementary power transmission device in response to the absence of first data including a valid response to the query message.

7. The power transmission device according to any one of claims 1-3, wherein, The first data includes control data for the power transmission.

8. The power transmission device as described in any one of claims 1-3, further comprising: A power controller (203, 301) is arranged to communicate control data for the power transmission with the complementary power transmission device. The power controller (203, 301) is arranged to communicate some control data with the complementary power transmission device via a first communication channel and to communicate other control data with the complementary power transmission device via a second communication channel.

9. The power transmission device as claimed in claim 1, wherein, The power transmission signal has a fixed non-zero amplitude in multiple subsequent decreasing power time intervals.

10. The power transmission device as claimed in claim 1, wherein, The frequency of the power transmission signal is higher during the reduced power time interval than during the power transmission time interval.

11. The power transmission device as claimed in claim 9, wherein, The frequency of the power transmission signal is higher during the reduced power time interval than during the power transmission time interval.

12. The power transmission device according to any one of claims 1-3, wherein, The power transmission device is the power receiver (105), and the complementary power transmission device is the power transmitter (101).

13. The power transmission device according to any one of claims 1-3, wherein, The power transmission device is the power transmitter (101), and the complementary power transmission device is the power receiver (105).

14. A method of operating a power transmission device for wireless power transmission from a power transmitter (101) to a power receiver (105), the power transmission device being one of the power transmitter and the power receiver, the method comprising: The power transmission coils (103, 107) transmit power to the complementary power transmission coils (107, 103) of the complementary power transmission device via a power transmission signal, the complementary power transmission device being the other of the power transmitter (101) and the power receiver (105); During power transmission, first data is communicated with the complementary power transmission device via a first communication channel by modulating the power transmission signal. During power transmission, power transmission control data is communicated with the complementary power transmission device via a second communication channel independent of the power transmission signal, wherein the communication data rate for the second communication channel is not less than ten times the communication data rate for the first communication channel. During power transmission, in response to the first data, it is determined whether the complementary power transmission device is present in the vicinity of the power transmission coils (103, 107); and In response to the detection that the complementary power transmission device is not present, the wireless power transmission from the power transmitter (101) to the power receiver (105) is limited; The power transmission signal employs a repetitive time frame during power transmission that includes at least a power transmission time interval and a reduced power time interval, wherein the power level of the power transmission signal is reduced during the reduced power time interval relative to the power transmission time interval; and wherein the communication of the first data is performed during the reduced power time interval.

15. A power transmission system for wireless power transmission from a power transmitter (101) to a power receiver (105), The power transmitter (101) includes: A power transmitter coil (103) is used to generate a power transmission signal for transmitting power to the power receiver (105); A first transmitter communicator (205) is used to communicate first data with the power receiver (105) via a first communication channel during power transmission by modulating the power transmission signal. as well as A second transmitter communicator (207) is used to communicate power transmission control data with a complementary power transmission device via a second communication channel independent of the power transmission signal during power transmission, wherein the communication data rate for the second communication channel is not less than ten times the communication data rate for the first communication channel; and The power receiver (105) includes: A power receiver coil (107) is used to receive power via the power transmission signal; A first receiver communicator (305) is configured to communicate the first data with the power receiver (105) via the first communication channel during power transmission; and A second receiver communicator (307) is used to communicate power transmission control data with the power transmitter (101) via the second communication channel during power transmission; Wherein, at least one of the power transmitter (101) and the power receiver (105) further includes: Presence detectors (209, 309) are used to determine, in response to the first data, during power transmission, whether the complementary power transmission device is present in the vicinity of the power transmission coils (103, 107), the complementary power transmission device being another of the power transmitter (101) and the power receiver (105) that is different from at least one of the above; and A power transmission controller (201, 301) is arranged to limit the wireless power transmission from the power transmitter (101) to the power receiver (105) in response to the detection that the complementary power transmission device is not present; The power transmission signal employs a repetitive time frame during power transmission that includes at least a power transmission time interval and a reduced power time interval, wherein the power level of the power transmission signal is reduced during the reduced power time interval relative to the power transmission time interval; and wherein the first transmitter communicator (205) and the first receiver communicator (305) are arranged to communicate the first data during the reduced power time interval.

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