Energy storage for a power receiver of a wireless power system

Abstract

This disclosure provides systems, methods and apparatuses for incorporating an energy storage unit in a cordless appliance for use in a wireless power system. The energy storage unit can provide energy to a bias supply circuit of the Power Receiver. The energy storage unit can provide energy to operate components of the Power Receiver (such as a controller, load disconnect switch, communication unit, memory, or timer, among other examples) when harvested bias power is unavailable or insufficient.

Description

ENERGY STORAGE FOR A POWER RECEIVER OF A WIRELESS POWERSYSTEMRELATED APPLICATIONS

[0001] This application claims priority benefit of India Provisional Patent Application No. 202411001388 filed January 8, 2024, the disclosure of which is incorporated herein.TECHNICAL FIELD

[0002] This disclosure relates generally to wireless power and some aspects relate to energy storage in a cordless appliance of a wireless power system.DESCRIPTION OF RELATED TECHNOLOGY

[0003] A wireless power system includes a Power Transmitter (PTx) and a Power Receiver (PRx). Inductive coupling can enable wireless power transfer between a primary coil of the Power Transmitter and a secondary coil of the Power Receiver. The primary coil of the Power Transmitter produces an electromagnetic field during a power state of the wireless power system. The electromagnetic field induces a voltage in the secondary coil of the Power Receiver when the secondary' coil is present in the electromagnetic field. Thus, the Power Transmitter can wirelessly transfer power to the Power Receiver using inductive coupling between the primary coil and the secondary’ coil. The Power Receiver can provide the received power to operate a load. Example loads might include a motor, a heating element, electronics, or a power storage device, among other examples. In an example kitchen environment, a magnetic power source (such as a kitchen hob) might include one or more Power Transmitters.

[0004] Some types of appliances might be constructed for use in a wireless power system such that the load can be operated using wireless power. A cordless appliance (sometimes referred to as a small domestic appliance, wireless power appliance, or other similar terms) is any device that includes a Power Receiver and that can be operated using wireless power received from a Power Transmitter, including hybrid devices which have both wired and wireless power capability. For example, a cordless appliance (such as a cordless blender, kettle, toaster, or cooking vessel, among other examples) might include the Power Receiver as well as a load. The appliance can be placed on a magnetic power source (or any apparatus that has a Power Transmitter) such that the Power Receiver of the appliance can receive wireless power from the Power Transmitter. The Power Receiver in the cordless appliancecaptures the magnetic field from the Power Transmitter and converts it to electric power or uses it for direct induction heating.BRIEF SUMMARY

[0005] The systems, methods, and apparatuses of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0006] One aspect of this disclosure can be implemented as a Power Receiver (PRx) for use in a wireless power system. The Power Receiver includes a PRx tank circuit capable of receiving wireless power from a Power Transmitter and providing the wireless power to a load, a communication unit to communicate with the Power Transmitter, a controller configured to control the wireless power in coordination with the Power Transmitter, and a bias supply circuit configured to obtain harvested bias powder from the PRx tank circuit, the communication unit, or both, and provide the harvested bias power to the controller. Furthermore, the Power Receiver includes an energy storage unit for providing energy to the bias supply circuit when the harvested bias powder is unavailable or below7a level required to operate the controller.

[0007] Another aspect of this disclosure can be implemented as a method of a Power Receiver. The method includes attempting to obtain harvested bias power from a PRx tank circuit, a communication unit, or both, and provide the harvested bias pow er to a controller. The method further includes using energy from an energy storage unit when the harvested bias power is unavailable or below a level required to operate the controller.

[0008] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0009] Like reference numbers and designations in the various drawings indicate like elements. Note that the relative dimensions of the figures may not be drawm to scale.

[0010] FIG. 1 shows a pictorial diagram of an example wireless pow er system.

[0011] FIG. 2 is a block diagram of an example wireless pow er system.

[0012] FIG. 3 illustrates a state diagram of a wireless power system and example use cases in which a Power Receiver has an integrated energy storage unit.

[0013] FIG. 4 illustrates a timing diagram and associated operations in various states of a wireless power system.

[0014] FIG. 5A illustrates an example Power Receiver capable of operating an impedance change circuit with an energy storage unit.

[0015] FIG. 5B illustrates an example impedance change circuit.

[0016] FIG. 6 illustrates an example Power Receiver capable of operating a disconnect switch with an energy storage unit.

[0017] FIG. 7 illustrates an example operations of a Power Receiver.

[0018] FIG. 8 illustrates a block diagram of an example apparatus for use in a wireless power system.DETAILED DESCRIPTION

[0019] The following description is directed to certain implementations for the purpose of describing innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. The described implementations can be implemented in any means, apparatus, system, or method for transmitting or receiving wireless power.

[0020] As described previously, a wireless power system includes a Power Transmitter (PTx) and a Power Receiver (PRx). A Power Transmitter also may be referred to as a wireless power transmission apparatus. A Power Receiver also may be referred to as a wireless power reception apparatus. Some examples of this disclosure are based on a kitchen environment. For example, the Power Transmitter might be part of a magnetic power source such as a hob, a countertop, or range. In some implementations, the Power Transmitter may include a surface-mounted primary coil, an integrated primary coil, a countertop-mounted primary' coil or a primary coil that is embedded or manufactured in a surface on which a Power Receiver can be placed. A Power Receiver includes a secondary coil configured to wirelessly receive power via inductive coupling with the primary coil of the Power Transmitter. The Power Receiver might be part of a cordless appliance such as a cordless blender, kettle, toaster, or cooking vessel, among other examples. Although the examples of this disclosure refer to a wireless power system in a kitchen environment, the disclosed techniques can be used with other types of wireless power systems or in other types of environments.

[0021] There are different wireless power standards that might use similar technology but are intended for different applications. For example, one wireless power standard might support wireless charging of smartphones or other mobile devices; a different wireless powerstandard might support power delivery to cordless kitchen appliances: and yet other wireless power standards might support charging for electric vehicles, robots, or drones. Some devices (such as smartphones) are operated using batteries that provide power for a processor. In contrast, other devices (such as kitchen appliances) are operated using a wired power source because the load (such as a motor or heating element) might require more power than is practical for a battery. However, in accordance with this disclosure, a Power Receiver can include an energy storage unit (such as a small battery) to enhance wireless power capability of a cordless appliance.

[0022] This disclosure provides systems, methods and apparatuses for incorporating an energy storage unit in a cordless appliance for use in a wireless power system. The energy storage unit can provide energy to a bias supply circuit of the Power Receiver. A bias supply circuit (sometimes referred to as ‘"bias supply" for brevity) provides power harvested from communications or power carriers. Typically, before wireless power transfer has begun (referred to as a pre-power state), the Power Receiver obtains the bias power by harvesting energy from communication signals. The bias pow er is used to operate a controller, a load disconnect switch, a communication unit, or other components of the Power Receiver other than the load. For example, the bias power is used to close a disconnect switch (thereby connecting the load to the Power Receiver) prior to power transfer (referred to as a “power state”). Once the wireless pow er transfer has begun, the bias powder can be obtained from the wireless power signal.

[0023] Absent the techniques of this disclosure, the typical mechanism for powering a controller or communication unit of the Power Receiver is based on bias power harvested from the communication and pow er signals of the Power Transmitter. Furthermore, there are occasions when the Power Transmitter fails to provide (or Power Receiver fails to harvest) enough power from communication circuit sufficient for the Power Receiver to operate before the power state. For example, the Power Transmitter and the Power Receiver might be collocated for a long time period resulting in a timeout condition. Alternatively, the Power Receiver might benefit from being activated by a controller of the cordless appliance rather than according to the bias power harvested from communication signals. To address these problems, and others, this disclosure provides techniques for incorporating an energy storage unit with the Power Receiver. The energy storage unit can provide energy to operate components of the Power Receiver (such as a controller, a load disconnect switch, an impedance change circuit, a communication unit, memory, or a timer, among other examples) when bias power is unavailable or insufficient.

[0024] Examples of an energy storage unit include a battery, a supercapacitor, a capacitor bank, or combination of storage elements, among other examples. While examples of this disclosure are based on an electrical energy storage, other types of energy storage can be used to generate power, including devices that can generate electrical power using thermal, mechanical, radiation, or chemical processes. The energy storage unit can be coupled to a bias supply circuit of the Power Receiver such that the energy storage unit provides sufficient electricity to operate the Power Receiver in addition to, or in the absence, of harvested bias power.

[0025] This disclosure provides several example scenarios describing how an energy storage unit is used in a Power Receiver. The example scenarios show existing wireless power protocols or processes can be modified to take advantage of an incorporated energy storage unit. Several example scenarios are based on a kitchen cordless appliance which might have unique operating properties compared to other cordless devices (such as smart phones). For example, one scenario describes how a cordless appliance with an integrated energy storage unit can support auto start or restart after being in a standby or off state (referred to as “OFF”). In some implementations, the cordless appliance can auto start or restart without user interaction, or based on an earlier user action (such as setting a timer or scheduling a start time).

[0026] In some implementations, a Power Receiver uses energy from the energy storage unit to auto start or restart after the Power Transmitter is in a standby state. The Power Receiver can cause the Power Transmitter to wake up from the standby state using an impedance change circuit of the Power Receiver that is at least partially powered using the energy' storage unit. An impedance change circuit can also be referred to as a wake-up circuit, impedance circuit, impedance-load switch, impedance-change toggle, or other terms. The impedance change circuit can be any type of circuit that the Power Receiver can temporarily activate to cause the Power Transmitter to detect an impedance change. When the Power Receiver makes a change to the impedance change circuit (such as toggling a switch), the Power Transmitter detects a change in reflected impedance, which causes the Power Transmitter to wake up from the standby state. Thus, the process of activating the impedance change circuit can also be referred to as a wake-up signal.

[0027] In a scenario in which a power outage (such as main power brown out or blackout) has occurred, the cordless appliance can use the energy storage unit to power volatile memory. A power outage can also be referred to as a stoppage in wireless power. In another scenario, the cordless appliance can use the energy storage unit to store information (such as cooking state, timer state, temperature or other parameters) in a non-volatile memory before switchingOFF (such as after a cooking operation or after a power outage). Thus, the cordless appliance can maintain state information about a cooking process or wireless power configuration. When the main power source returns, the Power Transmitter and Power Receiver might resume power transfer using previously negotiated wireless power configuration. Furthermore, the cordless appliance can resume a cooking operation or timer program. In yet another example scenario, the energy storage unit enables the Power Receiver to close and maintain the disconnect switch during a transition from a pre-power state to the power state. Harvested bias power might be insufficient to reliably close and maintain the disconnect switch resulting in chattering or faulty switch operation. The energy storage unit can supply or augment the bias power needed to close the disconnect switch until the bias power can be obtained from the wireless power signal.

[0028] Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. A cordless appliance can recover from power outage that would otherwise disrupt a cooking, heating, or kitchen process. The cordless appliance can improve reliability7and functionality7by incorporating the energy storage unit in conjunction with a wireless power protocol. The cordless appliance can mirror the user experience that a user might expect from a wired kitchen appliance while providing the convenience enabled by wireless power.

[0029] FIG. 1 shows a pictorial diagram of an example wireless power transfer system 100. The wireless power transfer system may include a Power Transmitter 102 and a Power Receiver 104. The Power Transmitter 102 includes a primary coil 106. When the primary coil 106 transmits the wireless power 108, it creates a magnetic field that induces a voltage in a secondary coil 110 of the Power Receiver 104. The Power Receiver 104 may include a secondary coil 110 configured to receive the wireless power 108. The components of the Power Transmitter 102 and the Power Receiver 104 are described in further detail with reference to FIG. 2.

[0030] For comparison purposes, FIG. 1 also shows a traditional wired appliance 112 operated using a wired power source 114. A goal of a kitchen wireless power technology is to provide the same or better user experience in a cordless appliance that a user would expect from a wired appliance 112. Instead of (or in addition to) a wired power source 114, a cordless appliance includes a Power Receiver 104 that can receive wireless power from the Power Transmitter 102. The Power Receiver 104 may be included in an appliance (such as a cordless kitchen appliance, among other examples) intended to operate on a wireless power transmitting surface configured with one or more primary7coils (such as a kitchen countertop, stovetop, or hob). FIG. 1 shows some examples 116a, 116b of appliances that may be usedwith a Power Transmiter 102. For example, the appliance may be a kettle (as illustrated). Other examples of appliances that may include a Power Receiver may include a slow cooker, a blender, a pot, a rice cooker, a coffee machine, a toaster, a broiler, a griddle, an electric pan, any type of appliance configured to heat a liquid or process food, among other examples. In one example 116a, the cordless appliance has both wired and wireless power capability, and might be referred to as a hybrid appliance. In another example 116b, the cordless appliance does not include a wired power capability and solely operates using wireless power.

[0031] In a kitchen environment, the Power Transmitter 102 may be included in a kitchen equipment such as a cooktop or hob. For example, in some implementations, a hob may include several locations for placement of objects. At least one of the locations may include a Power Transmitter 102 that supports wireless power transfer to an appliance that includes a Power Receiver 104. In some implementation, a Power Transmitter 102 may be integrated in a hob that is portable in nature. For example, a portable hob may include a battery or be capable of an external power source to power the Power Transmitter 102, and may be suitable for camping.

[0032] Some appliances operate based on user interaction to control ON and OFF operations. For example, some blenders or juicers might be designed with a button or other user interface for manual control to turn the appliance ON when the user intends to use them. This ensures that power is not wasted and that the appliance operates only when turned ON by the user. Other appliances might be designed to turn ON or OFF automatically to reduce user interaction. For instance, appliances like rice cookers, kettles, and coffee makers might be designed to automatically turn ON or OFF to heat food or liquid contents according to a schedule or temperature criteria. For example, the appliance might be configured to automatically turn ON according to a scheduled start time and automatically turn OFF or go to a “keep warm” process once a heating operation is completed. In one example, a user might place a cordless appliance (such as a kettle or coffee maker) on a Power Transmitter and set a scheduled start time. In some implementations, an integrated energy storage unit can enable a cordless appliance to have sufficient bias power to maintain a timer or to operate a controller configured with the schedule. Alternatively, or additionally, the energy storage unit can enable the cordless appliance to recover from a power outage and continue expected operations.

[0033] FIG. 2 is a block diagram of an example wireless power system 200. The example wireless power system 200 includes a Power Transmitter 102 and a Power Receiver 104. The Power Transmitter 102 includes a primary coil 106 and a PTx controller 210. The primary'coil 106 may be associated with a Power Transmitter circuit 206 (sometimes also referred to as a power signal generator, or a driver circuit, or a driver). The primary coil 106 may be a wire coil which transmits wireless power (which also may be referred to as wireless energy). The primary coil 106 may transmit wireless energy using an inductive or a resonant magnetic field. The Power Transmitter circuit 206 may include components (not shown) to prepare the wireless power. For example, the Power Transmitter circuit 206 may include one or more switches, drivers, series capacitors, rectifiers, inverters, or other components. In some implementations, the Power Transmitter circuit 206 includes an inverter and a PTx resonant tank circuit. The PTx controller 210 may be implemented as a microcontroller, dedicated processor, integrated circuit, application specific integrated circuit (ASIC) or any other suitable electronic device.

[0034] A power source 204 provides power to the power transmitter unit 208. In some implementations, the power source 204 may convert alternating current (AC) power to direct current (DC) power. For example, the power source 204 may include a converter that receives an AC power from an external power supply and converts the AC power to a DC power used by the Power Transmitter circuit 206. Alternatively, or additionally, a component (such as an inverter) of the Power Transmitter circuit 206 may convert the DC power to the AC power. The power source 204 may be integrated as part of the Power Transmitter 102 or may be external to the Power Transmitter 102. In some implementations, the Power Transmitter 102 causes the power source 204 to regulate the DC output voltage of the power source 204. For example, the PTx controller 210 can set DC voltage of the power source 204 based on information (such as a value indicating a requested power) received from the Power Receiver 104. The Power Transmitter 102 can receive power configuration information from the Power Receiver 104 and use the information to set a parameter (such as the DC output voltage of the power source 204). The Power Transmitter 102 can receive the power configuration information during various operating states, such as the discovery state or power state. In some implementations, the Power Transmitter 102 includes a DC-DC converter (not shown) between the power source 204 and the Power Transmitter circuit 206 to control the variable DC output voltage.

[0035] The PTx controller 210 is connected to a communication interface 212. The communication interface 212 is connected to a first communication coil 214. In some implementations, the communication interface 212 and the first communication coil 214 may be collectively referred to as a first communication unit. In some implementations, the first communication unit may support short-range radio frequency communication, such as Near Field Communication (NFC) or Bluetooth (BT). NFC is a technology by which data transferoccurs on a carrier frequency of 13.56 Megahertz (MHz). The first communication unit also may support any suitable communication protocol. The first communication unit may contain modulation and demodulation circuits to wirelessly communicate via the first communication coil 214. Alternatively, or additionally, the PTx controller 210 may use frequency, amplitude, current, or voltage modulation of a wireless power signal to communicate via an in-band communication link (not shown) that includes the primary coil 106.

[0036] In the example of FIG. 2, the cordless appliance 202 includes a Power Receiver 104 and a load 224. The Power Receiver 104 may include a secondary coil 110, a PRx tank circuit 236, a rectifier 220, a PRx controller 222, a communication interface 226, and a memory (not shown). In some implementations, the cordless appliance 202 also includes a load controller 230 and a user interface 252 (such as a button, switch, touchpad, indicator, touch screen, or wireless local area network interface). In some implementations, the load 224 can include a driver (not shown) for controlling at least one parameter such as charging current, speed, or torque of the load. In some implementations, the rectifier 220 may be omitted such as when the voltage induced in the secondary' coil 110 can directly power the load 224. The PRx tank circuit 236 can include a capacitor or other components to enable the secondary coil 110 to receive the wireless power 108 during the power state. Although not shown, a small capacitor can be used before the rectifier 220 and a load capacitance can be used after the rectifier 220 to match impedance and to filter a high frequency component of the rectifier voltage. Although shown as different components, some components may be packaged or implemented in the same hardware. For example, in some implementations, the PRx controller 222 and the load controller 230 may be implemented as a single controller. The PRx controller 222, the load controller 230, the communication interface 226, or any combination thereof, may be implemented as a microcontroller, dedicated processor, integrated circuit, application specific integrated circuit (ASIC) or any other suitable electronic device. The communication interface 226 and the second communication coil 228 can be collectively referred to as a second communication unit. The second communication unit might also include a power harvester (not shown) that can harvest energy from the communication signals and provide (arrow 244) the harvested bias power to a bias supply circuit 234. The bias supply circuit 234 can provide power to the PRx controller 222 (shown at arrow 250) and the load controller 230 (shown at arrow 248).

[0037] The PTx controller 210 may detect the presence or proximity of a Power Receiver 104. This detection may happen during a periodic pinging process of the communication interface 212. During the pinging process, the communication interface 212 supplies power to the communication interface 226 via communication signals 254 when the Power Receiver104 is in proximity to the Power Transmitter 102. The communication interface 226 may ■‘wake up” and power-up the PRx controller 222 using the bias supply circuit 234. The communication interface 226 can send a reply signal back to the communication interface 212 to confirm that it is a Power Receiver. Prior to power transfer, a handshaking process may take place during which the PTx controller 210 may receive identification and configuration data, among other information, from the Power Receiver 104. The PTx controller 210 may control characteristics of wireless power it provides to the Power Receiver 104 based on the configuration data.

[0038] A PRx controller 222 may be operationally coupled to the rectifier 220 and the communication interface 226. The communication interface 226 may contain modulation and demodulation circuits to wirelessly communicate via the second communication coil 228. Thus, the PRx controller 222 may wirelessly communicate feedback information to the PTx controller 210 via the communication interface 226 to the communication interface 212 using short-range radio frequency communication, such as NFC. Alternatively, or additionally, the PRx controller 222 may use load modulation to communicate via an in-band communication link (not shown) that includes the secondary coil 110.

[0039] A load controller 230 may be operationally coupled to the load 224 and the PRx controller 222 (or to the communication interface 226, coupling not shown in Fig. 2). The load controller 230 may detect changes to load states. The load controller 230 also may determine a load voltage reference and / or a power requirement of the load. The load controller 230 also may send load voltage references, load current, load power requirement and any other suitable information to the PRx controller 222 or the communication interface 226 for communication to the Power Transmitter 102. During a power state, the PRx controller 222 may additionally determine and provide one or more feedback information indicating a measured load voltage, load current, load power requirement, and power available to the load 224. In some feedback messages, the feedback information may include a reference voltage indicating a required voltage for the load 224. In some feedback messages, the feedback information may indicate an error in the output voltage of the load 224. In some feedback messages, the feedback information may include the required power for the load. Although the PRx controller 222 and load controller 230 are shown separately, they may be included in the same component of the Power Receiver 104.

[0040] Some appliances are equipped with safety features, such as a disconnect switch 232, that are operated in conjunction with the operating states. For example, the disconnect switch 232 might be maintained in an open position to prevent the flow of current to the load 224 when the Power Receiver 104 is in the pre-power states (the standby state, the discovery' state,and the connected state as described with reference to FIG. 3). Before transitioning to the power state, the PRx controller 222 might cause the disconnect switch 232 to move to a closed position to enable the flow of current to the load 224. In an emergency condition (such as excessive voltage or current), the PRx controller 222 might open the disconnect switch 232 to prevent damage to the load 224 or other components of the Power Receiver 104.

[0041] After the disconnect switch 232 is closed, the PRx controller 222 can communicate a message to the PTx controller 210 to cause the wireless power system to transition to the power state. Alternatively, or additionally, the PRx controller 222 can communicate a power request to begin the transmission of the wireless power 108. Once the wireless power 108 is being received by Power Receiver 104, the bias supply circuit 234 can use harvested bias power (arrow 242) from the PRx tank circuit 236 or voltage at the load 224. Alternatively, or additionally, some types of loads 224 can supply power (arrow 246) to the bias supplycircuit 234. In addition to providing power to the PRx controller 222 and load controller 230, the bias supply circuit 234 supplies power (arrow 240) to maintain the disconnect switch 232 in the closed position during normal operation of the power state.

[0042] In accordance with this disclosure, the cordless appliance 202 includes an energy storage unit 238. Although the energy storage unit 238 is illustrated as part of the Power Receiver 104, it can be collocated with the Power Receiver 104 as another component of the cordless appliance 202. The energy storage unit 238 can supply power (arrow 256) to the bias supply circuit 234. In some implementations, when the bias supply circuit 234 is obtaining enough harvested bias power from the communication signals 254 or the wireless power 108, the bias supply circuit 234 can provide power (arrow 258) to the energy storage unit 238. For example, the energy storage unit 238 can be a rechargeable battery. In other implementations, the energy storage unit 238 can be a small battery, such as a button cell battery. In some implementations, the energy storage unit 238 can be a charged using a temporary connection to an external power supply or using other electrical or mechanical means of charging, including some techniques that involve a user action to generate or connect energy for the energy storage unit 238.

[0043] The energy storage unit 238 provides power to the bias supply circuit 234 when the harvested bias power is unavailable. The harvested bias power is considered unavailable when there is no harvested bias power or when an amount of the harvested bias power is insufficient for operation of the controller or a load disconnect switch. For example, the harvested bias power may not be available if the Power Transmitter 102 has had a power outage or if the communication signals 254 have ceased due to a timeout condition.

[0044] FIG. 3 illustrates a state diagram 300 of a wireless power system and example use cases in which a Power Receiver has an integrated energy storage unit. The state diagram 300 illustrates the operating states in which the wireless power system may operate. When a Power Receiver is placed within an operating volume on the interface surface of a Power Transmitter, the two start to communicate with the aim to configure and control the power transfer. There are four operating states shown in FIG. 3: a standby state 302 (sometimes also referred to as a ping phase), a discovery state 304 (sometimes referred to as an identification phase), a connected state 306, and a power state 308 (sometimes referred to as a power transfer phase). The standby state 302, the discovery state 304, and the connected state 306 can collectively be referred to as pre-power states. A technical specification may define how the Power Transmitter and Power Receiver can transition between the operating states. For example, the wireless power system ty pically begins in the standby state 302 until the Power Transmitter detects a Power Receiver, moving it to the discovery state 304. In the discovery' state 304. the Power Transmitter establishes communication and receives the first identification information of the Power Receiver and its static configuration data. In the connected state 306 the Power Transmitter and Power Receiver exchange information to agree and adjust parameters related to wireless power transfer. In the power state 308, the Power Transmitter transmits wireless power to the Power Receiver. The Power Receiver may occasionally or periodically communicate status or feedback control messages to the Power Transmitter during the power state 308. The system can move to a reinitialization state (not shown) as needed to reinitialize or return to the standby state when communication, powering, or other activities are no longer taking place. Each of the operating states are briefly described herein for reference.

[0045] In the standby state 302, the Power Transmitter tries to establish communications with a Power Receiver. The Power Receiver may be just placed on the interface surface or may not be present during this operating state. The Power Transmitter may attempt to communicate or detect the presence of the Power Receiver. For example, the Power Transmitter may use an analog ping, out-of-band communication (such as NFC), a digital ping, impedance change detection, or any combination thereof, to determine that a compatible Power Receiver is present. Once the wireless power system determines that a Power Receiver is present (such as by confirming NFC communication), the wireless power system may transition to the discovery' state 304.

[0046] In the discovery state 304, the Power Receiver may establish communication with the Power Transmitter and send static configuration information (such as identification and configuration information) to the Power Transmitter. For example, the Power Transmittermay retrieve static configuration information from the Power Receiver via the NFC communication. The Power Transmitter and the Power Receiver may use this information to verify that they both use compatible versions of a technical specification or protocol for wireless power transfer. The Power Transmitter and Power Receiver may communicate basic settings or communicate regarding their respective capabilities. From the discovery state 304, the wireless power system may transition to the connected state 306.

[0047] In the connected state 306, the Power Transmitter and the Power Receiver may exchange further communications to negotiate the parameters that govern the power state. For example, a power negotiation can occur during the connected state 306. After negotiating the parameters, the Power Transmitter may be prepared to transfer wireless power and the Power Receiver may be prepared to receive the wireless power. The Power Transmitter may wait for a request or command from the Power Receiver before transitioning to the power state 308. This may be useful, for example, when a cordless appliance (such as a blender, toaster, mixer, or microwave, among other examples) is configured for use pending a user interaction. The user may initiate the power state 308 by a user interface (such as an activation switch) of the Power Receiver, which in turn communicates to the Power Transmitter to transition to the power state 308.

[0048] From the power state 308, the Power Transmitter and the Power Receiver may transition back to the connected state 306 until a next power transfer operation is needed. Alternatively, the wireless power system might transition to the standby state 302. In some implementations, if the Power Transmitter determines that the Power Receiver is moved, that the Power Receiver is no longer present in an operating environment of the Power Transmitter, or that a foreign object has been introduced during the conditional standby state, the Power Transmitter might transition to a reinitialization state (not shown) to reset or clear previous configurations for the previously-present Power Receiver.

[0049] Some operations, such as object detection and communication handshakes, are time sensitive. For example, a transition from the standby state 302 to the discovery state 304 is based on an object detection. The Power Transmitter typically detects the Power Receiver based on an impedance change. The Power Transmitter can detect the impedance change using its primary coil, communication coil, a detection coil, or any other ty pe of detection circuit that can detect changes in impedance reflected by an object in the operative environment. In some implementations, the Power Transmitter might measure voltages and / or currents in the communication circuit or PTx tank circuit (e g., primary coil) and monitor for a change above a threshold amount (such as 10% change in measurement, as an example). Because the impedance change procedure is based on a change, typically the PowerTransmitter detects the Power Receiver when the Power Receiver is first placed in the operative environment. However, if the Power Receiver is located there for a long time period (or following a blackout / brownout, restart), the Power Transmitter might timeout and move to the standby state 302. The Power Receiver cannot hold the Power Transmitter in the discovery state 304 (or the connected state 306) for an indefinite duration. In some cases, the Power Transmitter may decide that the Power Receiver is faulty or unresponsive. Shown at arrow 310, the wireless power system might move to the standby state 302 due to a time out condition where the Power Receiver has been located in the operative environment for a long time. The Power Transmitter may implement an upper time limit after which it will return to the standby state 302. The upper time limit might be based on energy conservation or safety considerations. Another scenario in which the Power Transmitter may return to the standby state 302 is a power outage (black out) or power fade (brown out) that causes the Power Transmitter to reset. Regardless of the reason, the Power Transmitter may return to the standby state (block 310) while the Power Receiver remains in proximity of the Power Transmitter.

[0050] Once the Power Transmitter is in the standby state, absent the techniques of this disclosure, the Power Transmitter might stay in the standby state until a user action (such as the removing and placing the appliance, or an input on a user interface on the Power Transmitter or the Power Receiver). When the Power Transmitter returns to the standby state 302 and the Power Receiver remains on the interface surface, the Power Transmitter might not detect impedance change that would normally be caused by the Power Receiver being initially placed on the interface surface. In a kitchen environment, a user might place a cordless appliance on a Power Transmitter and leave it there for a long time period or indefinitely. Requiring a user action might be impractical or diminish user experience.

[0051] Some appliances might be designed to automatically turn ON or OFF according to a schedule or temperature criteria. For an example, an appliance might obtain wireless power to perform a heating operation (such as cooking food or boiling a liquid, as examples). In some instances, it is desirable for the appliance to automatically turn ON at a particular time so that the heating operation is performed according to an end-user schedule. In some instances, it is desirable for the appliance to automatically turn ON for a cooking time, warming or reheating operation or to maintain a target temperature. Alternatively, or additionally, the cordless appliance might have a wireless Internet connectivity' or remote application that can trigger an appliance activation remotely.

[0052] Current techniques for managing automatic ON and OFF operation of an appliance are based on control messaging from the appliance to the Power Transmitter. For example,the appliance might remain in a connected state 306 of operation when not receiving wireless power for the heating or reheating operations. In the connected state 306, the appliance consumes power from the Power Transmitter to maintain periodic communication, controller operations, and sensor measurements. Thus, the appliance will continue to consume power during the OFF periods of operation. In some implementations, the appliance uses bias power harvested from an NFC signal from a communication interface of the Power Transmitter to maintain the connected state 306 and sensor measurements during the OFF periods of operation. Thus, the appliance relies on NFC-harvested power from the Power Transmitter. As mentioned before, the Power Transmitter may move to standby state after a threshold time of inactivity. If the Power Transmitter keeps the NFC field alive, the Power Receiver may continue to harvest power even during periods of inactivity, leading to inefficiencies and unnecessary power usage. In some cases the power usage might violate standby power requirements prescribed by regulatory agencies. To reduce power consumption, the Power Transmitter may return to the standby state 302 and may have to switch off the NFC field. This may prevent the Power Receiver from obtaining harvested bias power to maintain a timer or controller that implements the automatic ON or remote start unless the Power Receiver has another source of power (such as the energy storage unit provided by this disclosure).

[0053] Having described the state diagram 300 and example problems, FIG. 3 also illustrates example scenarios using an energy storage unit in a Power Receiver to address some of the afore-mentioned problems. In a first example (block 310), the energy storage unit can power a controller that responds to an activation (such as an automatic ON, restart after power outage, remote activation via wireless communication, etc.). When the controller determines to activate the cordless appliance, the energy storage unit and an impedance change circuit (such as described with reference to FIG. 5 A and FIG. 5B) can wake up the Power Transmitter from the standby state 302. For example, the Power Receiver can use power from the energy storage unit to make a change at the Power Receiver that causes the Power Transmitter to detect an impedance change. The impedance change at the Power Transmitter causes the Power Transmitter to wake up and proceed with object detection and transition to the discover^' state 304. The Power Receiver activating the impedance change circuit is an example of a wake-up signal. Alternatively, or additionally, the Power Receiver can transmit a radio frequency (RF) transmission (such as a communication or RF signal) to wake up the Power Transmitter.

[0054] In another example (block 330), the energy storage unit can provide power for the Power Receiver to maintain an appliance status, such as configuration or cooking information. During a power outage or power fade, the Power Transmitter might reset and restart the statediagram 300 from standby state 302 to the connected state 306 before returning to the power state 308 that was active before the power outage. This can result in a bad user experience, disruption in the cooking process, or even dangerous overheating in some cases. Using power from the energy storage unit, a Power Receiver can maintain information about cooking status. In some implementations, cooking information might be stored in volatile memory that can be maintained using power from the energy storage unit. When the power transfer resumes, the Power Receiver (such as the load controller or PTx controller) can continue the cooking schedule. Absent the techniques of this disclosure, the Power Receiver might start the cooking all over again (possibly resulting in overcooked food or liquid) or might not start the cooking at all (possibly resulting in no or late cooking).

[0055] In addition to maintaining information about the cooking status, the energy storage unit and memory can store configuration information, such as a negotiated power setting or other configuration settings exchanged during the discover}' state 304 and connected state 306 before the power outage. When the power returns, the Power Receiver can use the previous configuration (such as the previous negotiated value stored in the memory') for the negotiation to complete the negotiation process quickly with the Power Transmitter and move to power state. In some cases, the Power Transmitter also has stored configuration information or can accept the parameters from the Power Receiver, such that the discovery state 304 and / or connected state 306 can be abbreviated or omitted when the wireless power system is recovering from a power outage. In some implementations, if the Power Transmitter determines that the Power Receiver is present in the operating environment and that no foreign object is by during a foreign object detection (FOD) procedure, the Power Transmitter might omit an operation of the discovery state 304 or the connected state 306 that would otherwise be performed the first time a Power Receiver is placed on the Power Transmitter. For example, the Power Transmitter might determine that the Power Receiver is the same as previously detected before the outage based on a matching device identification or other indicia. The Power Transmitter might omit an authentication, one or more configuration messages, or a power negotiation message exchange, among other examples.

[0056] In a third example (block 340), the energy storage unit can provide sufficient power to close a disconnect switch before the Power Receiver transitions to the power state 308. As mentioned previously, the disconnect switch is typically closed using bias power. In some cases, the harvested bias power is lower than needed to reliably close the disconnect switch. Closing the disconnect switch can require sufficient power (for example: 100 milliwatts (mW) to 250 mW for a relay type of switch). The harvested bias power may be insufficient to close the switch or keep the switch closed for various reasons. For example, if there is a largemisalignment between Power Transmitter and Power Receiver, there could be inefficient coupling to transfer enough power. Different NFC coil sizes can lead to bad coupling. Large Z distance can also lead to bad coupling. If the harvested bias power is not enough to reliably close and maintain the close state of the disconnect switch, it is possible for the disconnect switch to fail, repeated switch open / close. or simply not close at all. Failure to maintain the switch in the closed position during the power state can lead to load disconnect and dangerously high current on the Power Transmitter. This can also cause arcing in the switch contacts for a relay type of switch, and lead to contact wear and tear or permanent fusing of the contacts of the switch. Having an energy storage unit enables the Power Receiver to reliably close the disconnect switch before the power state 308 and also operate the controller to mitigate problems that might result from insufficient harvested bias power before or during the power state 308.

[0057] FIG. 4 illustrates a timing diagram 400 and associated operations in various states of a wireless power system. The timing diagram 400 is used to describe the operations of a Power Receiver 104 (PRx) and a Power Transmitter 102 (PTx). Although described as operations of the Power Receiver 104 and the Power Transmitter 102, it should be apparent that the operations might be performed by a PTx controller and a PRx controller, respectively. The Power Receiver 104 and the Power Transmitter 102 may follow the state diagram of various operating states, as described with reference to FIG. 3. FIG. 4 also shows the state of the communication channel 406 (NFC) in relation to the described operations.

[0058] For brevity, the details of the initial instance of the standby state 302, the discovery state 304, and the connected state 306 are briefly described in FIG. 4. During the standby state 302, a user may place an appliance having the Power Receiver 104 in an interface space of the Power Transmitter 102. The Power Transmitter 102 might transmit a detection signal 402 and detect the Power Receiver 104. For example, the Power Transmitter 102 can detect the Power Receiver 104 based on an impedance change 404 caused when the Power Receiver 104 enters the magnetic field of the detection signal 402. As a result of the impedance change 404, the Power Transmitter 102 detects the Power Receiver 104 and enters the discovery state 304. The discovery state 304 might include one or more discovery state messages 408a, 408b (such as identification and configuration messages and / or NFC data exchange format (NDEF) messages) and a state transition request message. A “NEXT” message is a state transition request message that indicates a request to transition to another state and the requested state (for example, the “NEXT / con” message is a state transition request message to transition to the connected state). The recipient of a state transition request message may respond with a response message ("RESP / ok"). The “RESP” message might indicate okay (“ok”), not okay("nok"), not defined ("nd"), or busy ("bsy"). In some implementations, the "RESP message is a response that can indicate acknowledgement ("ack"), non-acknowledgement ("nak") or not defined ("nd").

[0059] Details for the connected state 306 are omitted from FIG. 4 for brevity. The connected state 306 might include one or more connected state messages 410a (such as power negotiation messages). Furthermore, the Power Transmitter 102 might perform a FOD procedure during the connected state 306 to determine that no foreign objects are present. At some point, the Power Receiver 104 transmits a power request message 414 to initiate power transfer in a power state 308. During the power state 308, the Power Transmitter 102 transmits a wireless power signal 416 to the Power Receiver 104. On the communication channel 406, communication 412 might occur during the pre-power states. Although shown as a continuous communication 412, the communication 412 might include periods of inactivity, such as during FOD or pre-power coupling factor measurement periods. During the power state, the communication channel 406 might use communication slots 418a, 418b at zero-cross events of the wireless power signal 416. Not all zero cross events might be used for inserting a communication slot.

[0060] In the example of FIG. 4, the power state 308 is disrupted for any of a variety of reasons. For brevity7, the disruption is shown as an undefined state 424. For example, when the initial heating operation is complete, the Power Receiver 104 might communicate a message to transition to the connected or standby state 422. Alternatively, the Power Transmitter 102 might return to the standby state 422 due to a time out if the Pow er Receiver 104 remains in the connected state 306 for too long. In another example, a powder disruption (blackout or brownout) might cause the Power Transmitter 102 to reset and enter the standby state 422. In yet another example, the Power Receiver 104 may be programmed with an auto start or remote start capability such that it can activate after an idle period.

[0061] At some point after being in the undefined state 424, the Power Receiver 104 detects an appliance activation 430. The appliance activation 430 can be a button or input via a user interface. Alternatively, the appliance activation 430 can be a signal from the PTx controller (powdered by7the energy storage unit) to auto start or restart the Power Receiver 104 after a pow er outage or inactive period. In yet another example, the appliance activation 430 can be a message received via a wireless Internet connection (also powered by the energy storage unit) such that a user or server can remotely activate the Power Receiver 104 using the message. Based on detecting the appliance activation 430, the Powder Receiver 104 can trigger a wake-up signal to wake up the Power Transmitter 102. This disclosure includes severalexample implementations of a wake-up signal including some that are based causing the Power Transmitter 102 to detect an impedance change 432.

[0062] In one example (as shown in FIG. 4), the wake-up signal is based on an impedance change 432 that the PRx causes by activating an impedance change circuit (such as described with reference to FIG. 5 A and FIG. 5B). The energy storage unit 238 can supply power to the impedance change circuit to make a change that will cause the Power Transmitter 102 to detect the impedance change 432. In another example (not shown), the Power Receiver 104 can use power from the energy storage unit 238 to transmit a wake-up signal in the form of a radio frequency transmission. In yet another example, the wake-up signal can be any transmission or circuit change that will alter the magnetic field of the Power Transmitter 102 in such a way that will cause the Power Transmitter 102 to detect the impedance change 432. In some implementations, the wake-up signal is any process that exploits an object detection mechanism of the Power Transmitter 102 to cause the Power Transmitter 102 to detect the Power Receiver 104 and / or transition from the undefined state 424 to a one of the pre-power states 420.

[0063] After the Power Transmitter wakes up, the Power Transmitter 102 and the Power Receiver 104 can resume one of the pre-power states 420 (such as the discovery state 304 or the connected state 306). In some implementations, the Power Transmitter 102 might abbreviate or omit the discovery messages and proceed to the connected state messages 410c, 410d to resume power transfer based on a previous configuration.

[0064] In some implementations, the Power Transmitter 102 and the Power Receiver 104 might perform one or more pre-power operations associated with pre-power states 420 (such as the discovery state and the connected state). The Power Transmitter may verify that the appliance on the interface surface is the same as the one that was left before the undefined state 424. For example, the Power Transmitter can compare the appliance identification (ID) information with a previous appliance ID information stored before the conditional standby state. If a new appliance is detected (meaning the appliance ID information is not the same as before the conditional standby state), then the Power Transmitter will start with a fresh discovery and connected state with the new appliance. Otherwise, if the same appliance is present, the Power Transmitter 102 might continue with the pre-power operations. In some implementations, the pre-power operations might include an FOD procedure to determine that no foreign object was introduced during the undefined state 424. The Power Transmitter also may verify that the appliance alignment on interface surface is within an acceptable range in case the appliance might have moved during the sleeping time undefined state 424. In someimplementations, the pre-power operations might omit one or more operations that would normally have occurred during a first instance of the pre-power states.

[0065] FIG. 5A illustrates an example Power Receiver 500 capable of operating an impedance change circuit with an energy storage unit. The example Power Receiver 500 may be an example of the Power Receiver 104 described with reference to FIG. 1 through FIG. 4. The Power Receiver 500 may be included in an appliance. The Power Receiver 500 might include a load 224 or the load 224 may be component of the appliance that also includes the Power Receiver 500. The Power Receiver 500 includes a secondary coil 110. a second communication coil 228, a communication interface 226, and a PRx controller 222 as described with reference to FIG. 2. In some implementations, the Power Receiver 500 may or may not include a rectifier (not shown in FIG. 2). FIG. 5A also shows an example PRx tank circuit 236 that includes a series capacitor 502 coupled to one or more legs of the secondary coil 110. Alternatively, or additionally, the PRx tank circuit 236 includes a parallel capacitor 504 coupled between legs of the secondary coil 110. The example Power Receiver 500 includes a disconnect switch 232 connected in a series between one of the legs of the secondary coil 110 and the load 224. Although the disconnect switch 232 is shown as being connected in series with the series capacitor 502. other configurations are possible. The Power Receiver 500 also includes the bias supply circuit 234 and the energy storage unit 238 as described with reference to FIG. 2.

[0066] FIG. 5 A shows two example impedance change circuits 510a. 510b. In one example, the impedance change circuit 510a is located in the secondary' coil 110 or the PRx tank circuit 236. In another example, the impedance change circuit 510b is located with the second communication coil 228. In other examples (not shown), the impedance change circuit can be a separate circuit not coupled to either of the power reception unit or communication unit. The impedance change circuit can be any circuit that uses power from the energy storage unit 238 (possibly via the bias supply circuit 234) to simulate an impedance change or otherwise generate a condition to wake-up a Power Transmitter (not shown).

[0067] FIG. 5B illustrates an example impedance change circuit 526. The example impedance change circuit 526 is based on either of the impedance change circuits 510a, 510b shown in FIG. 5A; and could be implemented as the first example impedance change circuit 510a (located at the secondary coil) or the second example impedance change circuit 510b (located at the communication coil). The impedance change circuit 526 might include a load component 520, a switch component 522 (shown as a transistor, for example), or both. The switch component 522 can be realized using silicon switch, Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) switch, electromechanical switch or of that sort. The loadcomponent 520 can be any type of load, such as a resistor, a capacitor, diode, lighting component, mechanical load, or any combination of components. In the example shown in FIG. 5B, the PRx controller 222 sends a signal 524 to activate power from the energy storage unit 238 (possibly via the bias supply circuit 234) to apply to the switch component 522. The power from the energy storage unit 238 is shown as an input (512a or 512b) to the switch component 522 to simulate an impedance change. In some implementations, the PRx controller 222 can directly send a signal (such as input 512a or 512b) to the impedance change circuit 526 (510a or 510b)

[0068] FIG. 6 illustrates an example Power Receiver 600 capable of operating a disconnect switch with an energy storage unit. The example Power Receiver 600 may be an example of the Power Receiver 104 described with reference to any of the Figures of this disclosure. The Power Receiver 500 includes a secondary coil 110, a second communication coil 228, a communication interface 226, and a PRx controller 222, load 224, PRx tank circuit 236, bias supply circuit 234, and energy storage unit 238 as described with reference to FIG. 2. To close the disconnect switch 232 before entering the power state and to keep it in the closed condition throughout the power state, the PRx controller 222 sends a control signal 604 that activates a switch power 602 to close the disconnect switch 232. The switch power 602 can come from the energy storage unit 238 via the bias supply circuit 234 (as shown in FIG. 6) or directly from the energy storage unit 238. Alternatively, the switch power 602 can be supplied from the PRx controller 222 after the PRx controller 222 obtains power from the energy storage unit 238 and bias supply circuit 234. The energy storage unit 238 may be designed to ensure the disconnect switch 232 does not open as long as control signal 604 is provided for its closure, even when the Power Receiver 600 has insufficient energy harvesting for various reasons.

[0069] FIG. 7 illustrates example operations 700 of a Power Receiver. In block 702, the Power Receiver attempts to obtain harvested bias power from a PRx tank circuit, a communication unit, or both, and provide the harvested bias power to a controller. In block 704, the Power Receiver uses energy from an energy storage unit when the harvested bias power is unavailable or below a level required to operate the controller.

[0070] In some implementations, the Power Receiver generates, via an impedance change circuit, a wake-up signal using energy from the energy storage unit. In some implementations, the wake-up signal is designed to exploit an object detection mechanism of the Power Transmitter to wake up the Power Transmitter by causing the Power Transmitter to detect an impedance change. The Power Receiver might generate the wake-up signal based on a user interface command, a programmed schedule, or a message received via a network interface.The impedance change circuit can be integrated with, or coupled to, a secondary coil of the PRx tank circuit, an antenna of the communication unit, or a separate circuit.

[0071] In some implementations, the energy storage unit provides sufficient energy to a memory element to maintain a volatile memory state of the memory element following a power outage until the Power Transmitter and Power Receiver resume wireless power transfer.

[0072] In some implementations, the energy storage unit supplies power to the controller to enable the controller to maintain a load schedule when the harvested bias power is unavailable.

[0073] In some implementations, the Power Receiver uses energy from the energy storage unit to close and maintain a disconnect switch of the PRx tank circuit based on a control signal from the controller when the harvested bias power is unavailable (or insufficient).

[0074] In some implementations, the Power Receiver uses energy from the energy storage unit to power a network interface of the Power Receiver when the harvested bias power is unavailable to power the network interface.

[0075] FIG. 8 illustrates a block diagram of an example apparatus for use in a wireless power system. In some implementations, the apparatus 800 may be a wireless power transmission apparatus (such as the Power Transmitter 102) described herein. The apparatus 800 can include a processor 802 (possibly including multiple processors, multiple cores, multiple nodes, or implementing multi-threading, etc.). The apparatus 800 also can include a memory 804. The memory 804 may be system memory' or any one or more of the possible realizations of computer-readable media described herein. The apparatus 800 also can include a bus 806 (such as PCI, ISA, PCI-Express, HyperTransport®, InfiniBand®, NuBus,® AHB, AXI, etc.).

[0076] The apparatus 800 may include one or more controllers 808 (such as a PTx controller). In some implementations, the controller 808 can be distributed within the processor 802, the memory 804, and the bus 806. The controller 808 may perform some or all of the operations described herein. For example, the controller 808 may implement the processes described with reference to any one of FIG. 1 through FIG. 7, or any combination thereof.

[0077] The memory 804 can include computer instructions executable by the processor 802 to implement the functionality of the implementations described herein. Any one of these functionalities may be partially (or entirely) implemented in hardware or on the processor 802. For example, the functionality' may be implemented with an application specific integrated circuit, in logic implemented in the processor 802, in a co-processor on a peripheraldevice or card, etc. Further, realizations may include fewer or additional components not illustrated in FIG. 8. The processor 802, the memory 804, and the controller 808 may be coupled to the bus 806. Although illustrated as being coupled to the bus 806, the memory 804 may be coupled to the processor 802 or the controller 808.

[0078] The apparatus 800 also includes an energy storage unit 810. The energy storage unit 810 might implement any of the operations described with reference to FIG. 1 through FIG. 7. For example, the energy storage unit 810 might process a request message from a Power Receiver requesting to enter a conditional standby state. The energy storage unit 810 might implement a timer or counter to determine when an expiration of the sleeping time occurs. The energy storage unit 810 might initiate one or more operations to wake the Power Receiver after expiration of the sleeping time.

[0079] FIG. 1 through FIG. 8 and the operations described herein are examples meant to aid in understanding example implementations and should not be used to limit the potential implementations or limit the scope of the claims. Some implementations may perform additional operations, fewer operations, operations in parallel or in a different order, and some operations differently.

[0080] The foregoing disclosure provides illustration and description but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects. While the aspects of the disclosure have been described in terms of various examples, any combination of aspects from any of the examples is also within the scope of the disclosure. The examples in this disclosure are provided for pedagogical purposes. Alternatively, or in addition to the other examples described herein, examples include any combination of the following implementation options (enumerated as clauses for reference).

[0081] Clauses

[0082] Clause 1. A Power Receiver (PRx) for use in a wireless power system, the PRx including: a PRx tank circuit capable of receiving wireless power from a Power Transmitter and providing the wireless power to a load; a communication unit to communicate with the Power Transmitter; a controller configured to control the wireless power; a bias supply circuit to obtain harvested bias power from the PRx tank circuit, the communication unit, or both, and provide the harvested bias power to at least the controller; and an energy storage unit to provide energy to the bias supply circuit when the harvested bias power is unavailable or below a threshold amount.

[0083] Clause 2. The Power Receiver of clause 1. where the threshold amount is an amount of power required to operate at least the controller.

[0084] Clause 3. The Power Receiver of clause 1 or 2. further including: an impedance change circuit capable of generating a wake-up signal using energy from the energy storage unit.

[0085] Clause 4. The Power Receiver of clause 3, where the wake-up signal is to wake up the Power Transmitter by causing the Power Transmitter to detect an impedance change.

[0086] Clause 5. The Power Receiver of clause 3 or 4, where the impedance change circuit is integrated with, or coupled to, at least one of: a secondary’ coil of the PRx tank circuit, or an antenna of the communication unit.

[0087] Clause 6. The Power Receiver of any one of clauses 1 to 5, further including: a memory element, where the energy storage unit provides energy to maintain a volatile memory state of the memory element following a stoppage in power transfer from the power transmitter.

[0088] Clause 7. The Power Receiver of any one of clauses 1 to 6, where the energy storage unit supplies power to a load controller to enable the load controller to operate the Power Receiver according to a schedule when the harvested bias power is unavailable.

[0089] Clause 8. The Power Receiver of any one of clauses 1 to 7, where the energy storage unit provides energy to close and maintain a disconnect switch of the PRx tank circuit based on a control signal from the controller when the harvested bias power is unavailable to close and maintain the disconnect switch.

[0090] Clause 9. The Power Receiver of any one of clauses 1 to 8. further including: a network interface communicatively coupling the Power Receiver to a wireless network, where the energy’ storage unit provides energy’ to power the netw ork interface when the harvested bias power is unavailable to power the network interface.

[0091] Clause 10. The Power Receiver of any one of clauses 1 to 9, where the energy storage unit includes at least one of: a battery’, a supercapacitor, a capacitor bank, or combinations thereof.

[0092] Clause 11. A method of a Power Receiver (PRx), the method including: attempting to obtain harvested bias power from a PRx tank circuit, a communication unit, or both, and provide the harvested bias power to a controller; and using energy from an energy storage unit when the harvested bias power is unavailable or below a level required to operate the controller.

[0093] Clause 12. The method of clause 11, further including: generating, via an impedance change circuit, a wake-up signal using energy from the energy storage unit.

[0094] Clause 13. The method of clause 12, where the wake-up signal is to wake up the Power Transmitter by causing the Power Transmitter to detect an impedance change.

[0095] Clause 14. The method of clause 12 or 13, further including: generating the wakeup signal based on a determination to activate the Power Receiver in response to at least one of: a user interface command, a programmed schedule, or a message received via a network interface.

[0096] Clause 15. The method of any one of clauses 12 to 14, where the impedance change circuit is integrated with, or coupled to, at least one of: a secondary coil of the PRx tank circuit, or an antenna of the communication unit.

[0097] Clause 16. The method of any one of clauses 11 to 15, further including: providing energy from the energy storage unit to a memory element to maintain a volatile memory state of the memory element following a power outage until the Power Transmitter and Power Receiver resume wireless power transfer.

[0098] Clause 17. The method of any one of clauses 11 to 16. further including: supplying power from the energy storage unit to the controller to enable the controller to maintain a load schedule when the harvested bias power is unavailable.

[0099] Clause 18. The method of any one of clauses 11 to 17, further including: using energy from the energy storage unit to close and maintain a disconnect switch of the PRx tank circuit based on a control signal from the controller when the harvested bias power is unavailable.

[0100] Clause 19. The method of any one of clauses 11 to 18, further including: using energy from the energy7storage unit to power a network interface of the Power Receiver when the harvested bias power is unavailable to power the network interface.

[0101] Another innovative aspect of the subject matter described in this disclosure can be implemented as a computer-readable medium having stored therein instructions which, when executed by a processor, causes the processor to perform any one of the above-mentioned functionalities.

[0102] Another innovative aspect of the subject matter described in this disclosure can be implemented as a system having means for implementing any one of the above-mentioned functionalities.

[0103] Another innovative aspect of the subject matter described in this disclosure can be implemented as an apparatus having one or more processors configured to perform one or more operations from any one of the above-mentioned methods.

[0104] As used herein, a phrase referring to “at least one of’ or “one or more of’ a list of items refers to any combination of those items, including single members. For example, “at least one of: a, b, or c” is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c.

[0105] The various illustrative components, logic, logical blocks, modules, circuits, operations and algorithm processes described in connection with the implementations disclosed herein may be implemented as electronic hardware, firmware, software, or combinations of hardware, firmware or software, including the structures disclosed in this specification and the structural equivalents thereof. The interchangeability of hardware, firmware and software has been described generally , in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits and processes described above. Whether such functionality is implemented in hardware, firmware or software depends upon the particular application and design constraints imposed on the overall system.

[0106] The hardware and data processing apparatus used to implement the various illustrative components, logics, logical blocks, modules and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD). discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, particular processes, operations and methods may be performed by circuitry that is specific to a given function.

[0107] As described above, some aspects of the subject matter described in this specification can be implemented as software. For example, various functions of components disclosed herein, or various blocks or steps of a method, operation, process or algorithm disclosed herein can be implemented as one or more modules of one or more computer programs. Suchcomputer programs can include non-transitory processor-executable or computer-executable instructions encoded on one or more tangible processor-readable or computer-readable storage media for execution by, or to control the operation of, a data processing apparatus including the components of the devices described herein. By way of example, and not limitation, such storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store program code in the form of instructions or data structures. Combinations of the above should also be included within the scope of storage media.

[0108] Various modifications to the implementations described in this disclosure may be readily apparent to persons having ordinary7skill in the art, and the generic principles defined herein may be applied to other implementations without departing from the scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

[0109] Additionally, various features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. As such, although features may be described above as acting in particular combinations, and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0110] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one or more example processes in the form of a flowchart or flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In some circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program componentsand systems can generally be integrated together in a single software product or packaged into multiple software products.

Claims

CLAIMSWhat is claimed is:

1. A Power Receiver (PRx) for use in a wireless power system, the PRx comprising: a PRx tank circuit capable of receiving wireless power from a Power Transmitter and providing the wireless power to a load; a communication unit to communicate with the Power Transmitter; a controller configured to control the wireless power; a bias supply circuit to obtain harvested bias power from the PRx tank circuit, the communication unit, or both, and provide the harvested bias power to at least the controller; and an energy’ storage unit to provide energy to the bias supply circuit when the harvested bias power is unavailable or below a threshold amount.

2. The Power Receiver of claim 1, wherein the threshold amount is an amount of power required to operate at least the controller.

3. The Power Receiver of claim 1 or 2, further comprising: an impedance change circuit capable of generating a wake-up signal using energy from the energy storage unit.

4. The Power Receiver of claim 3, wherein the wake-up signal is to wake up the Power Transmitter by causing the Power Transmitter to detect an impedance change.

5. The Power Receiver of claim 3 or 4, wherein the impedance change circuit is integrated with, or coupled to, at least one of: a secondary’ coil of the PRx tank circuit, or an antenna of the communication unit.

6. The Power Receiver of any one of claims 1 to 5, further comprising: a memory’ element, wherein the energy’ storage unit provides energy to maintain a volatile memory state of the memory element follow ing a stoppage in power transfer from the power transmitter.

7. The Power Receiver of any one of claims 1 to 6, wherein the energy storage unit supplies power to a load controller to enable the load controller to operate the Power Receiver according to a schedule when the harvested bias power is unavailable.

8. The Power Receiver of any one of claims 1 to 7. wherein the energy storage unit provides energy to close and maintain a disconnect switch of the PRx tank circuit based on a control signal from the controller when the harvested bias power is unavailable to close and maintain the disconnect switch.

9. The Power Receiver of any one of claims 1 to 8, further comprising: a network interface communicatively coupling the Power Receiver to a wireless network, wherein the energy storage unit provides energy to power the network interface when the harvested bias power is unavailable to power the network interface.

10. The Power Receiver of any one of claims 1 to 9, wherein the energy storage unit includes at least one of: a battery, a supercapacitor, a capacitor bank, or combinations thereof.

11. A method of a Power Receiver (PRx), the method comprising: attempting to obtain harvested bias power from a PRx tank circuit, a communication unit, or both, and provide the harvested bias power to a controller; and using energy from an energy storage unit when the harvested bias power is unavailable or below a level required to operate the controller.

12. The method of claim 11, further comprising: generating, via an impedance change circuit, a wake-up signal using energy from the energy storage unit.

13. The method of claim 12, wherein the wake-up signal is to wake up the Power Transmitter by causing the Power Transmitter to detect an impedance change.

14. The method of claim 12 or 13, further comprising: generating the wake-up signal based on a determination to activate the Power Receiver in response to at least one of: a user interface command, a programmed schedule, or a message received via a network interface.

15. The method of any one of claims 12 to 14. wherein the impedance change circuit is integrated with, or coupled to, at least one of: a secondary coil of the PRx tank circuit, or an antenna of the communication unit.

16. The method of any one of claims 11 to 15, further comprising: providing energy from the energy storage unit to a memory element to maintain a volatile memory state of the memory element following a power outage until the Power Transmitter and Power Receiver resume wireless power transfer.

17. The method of any one of claims 11 to 16, further comprising: supplying power from the energy storage unit to the controller to enable the controller to maintain a load schedule when the harvested bias power is unavailable.

18. The method of any one of claims 11 to 17, further comprising: using energy from the energy storage unit to close and maintain a disconnect switch of the PRx tank circuit based on a control signal from the controller when the harvested bias power is unavailable.

19. The method of any one of claims 11 to 18, further comprising: using energy from the energy storage unit to power a network interface of the Power Receiver when the harvested bias power is unavailable to power the network interface.

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