Patent Description:
<CIT> provides an example of resonant induction wireless power transmission apparatus.

According to various embodiments of the systems and methods described herein, a power transmitter provides wireless power to a receiver. The systems and methods described herein may be implemented with any of a wide variety of transmitter and receiver sizes, types, configurations, etc. to satisfy the demands of various applications. Many of the example embodiments described herein are provided in the context of a wireless power transmitter used to provide wireless power to a receiver of an unmanned aerial vehicle (UAV) sometimes referred to as unmanned aerial systems (UASs). A beamform calculator may determine a target beamform suitable for providing wireless power based on a relative location of the target device and the power transmitter. An updated or revised target beamform may be calculated based on the movement of one or both of the target device and the power transmitter. That is, an optimized beamform may be calculated for each location of the target device relative to the power transmitter.

Updated target beamforms may be calculated based on the relative movement of the power transmitter and receiver of the target device. The transmitted beamform may be adjusted based on, for example, a determined location of the receiver of the target device and/or channel calculations to maintain one or more characteristics of the wireless power transfer within predetermined thresholds and/or for optimization of such characteristics. An example of location-based target beamforming is described in <CIT>, titled Non-Gaussian Beamforming for Wireless Power Transfer Optimization.

This disclosure particularly relates to wireless power receiver components and feedback control circuits to convert received EMR into direct current (DC) power for storage and/or consumption by an electronic device. Multiple feedback controls associated with different portions of the wireless power receiver may operate on various time-scales to optimize the power transfer and/or maintain power transfer within predefined limits or ranges. Wireless power receivers may be integrated within, attached to, or otherwise associated with any of a wide variety of electronic devices including, without limitation, mobile phones, tablet computing devices, wearable tech devices, watches, laptop computers, UAVs, robots, autonomous sensors, mobile battery storage devices, automobiles, busses, passenger and cargo trains, computer peripheral devices, autonomous vehicles, sensor arrays, and other mobile or stationary devices that consume electricity.

In one embodiment, wireless power receivers, utilizing the systems and methods described herein, provide power to a wireless base station configured to provide wireless communication access to other devices (e.g., Wi-Fi or LTE signals to mobile devices). The wireless base station may be deployed remotely and powered via wireless power received from a wireless power transmitter.

Many of the examples described herein, including the illustrated embodiments, relate to wireless power transfer via a stationary or mobile power transmitter to a mobile UAV. Nevertheless, many of the principles described in the context of powering UAVs are equally applicable to wireless power received to power other types of devices, whether mobile or stationary. Specifically, any of a wide variety of devices may be configured with one or more receiving antennas to receive electromagnetic energy also known as electromagnetic radiation (EMR) from a power transmitter. The antennas convert the EMR (e.g., microwave RF signals) into an AC electrical current. A converter may convert the AC electrical current into a DC electrical current. This general process, frequently described herein in the context of a UAV, can be applied or easily adapted to a wide variety of other devices. In some embodiments, a single-element receiver configured to receive EMR from a power transmitter may be used instead of a multi-element receiver. The antennas may operate to receive wireless power at a fixed frequency and/or may be adapted or tuned to receive wireless power at different frequencies. Examples of possible frequencies include <NUM>, <NUM>, <NUM>, etc..

As an example, a power transmitter may provide wireless power in the form of an electromagnetic signal to one or more receivers on one or more UAVs. A wireless power receiver, or simply "receiver" or "EMR receiver," may have a single antenna (or antenna element) or have multiple antennas (or antenna elements). The receiver may additionally include one or more transponders, reflectors, receivers, transceivers, and/or transmitters that are dedicated to or additionally configured to send and/or receive data to and/or from the power transmitter.

According to the invention, a tunable multi-timescale wireless rectification system may include a plurality of antennas, a plurality of rectifying devices, a plurality of impedance-matching components, and a plurality of DC-to-DC converters. The DC-to-DC converters may control the power delivered to load(s), such as energy storage and/or consumption devices of the UAV. The tunable multi-timescale wireless rectification system may include an antenna feedback control to modify the AC power delivered from the antennas to the rectifying devices. The antenna feedback control may modify a characteristic of one or more of the antennas. An impedance feedback control may modify a characteristic of one or more of the impedance-matching components. The antenna feedback control and/or the impedance feedback control may operate on a first timescale that is relatively fast.

For example, the antenna and/or impedance feedback control may operate to modify a characteristic of the antenna to decrease or increase the gain or frequency response in response to increased or decreased power being delivered from a wireless power transmitter. Any of the various feedback controls may be based, at least in part, on data received from the wireless power transmitter or an associated remote system. In various embodiments, the controller communicates with the remote transmitter via a radio frequency (RF) link, Bluetooth, Wi-Fi (based on reflected portions of the incoming power signal), an optical link (e.g., infrared, visible, or ultraviolet), or the like.

A controller associated with a multi-timescale wireless rectification system may adjust a setting of one or more of remote transmitters, transmitting antennas, receiving antennas, rectifying devices, impedance-matching components, DC-to-DC converters, and/or other elements. Additionally, or alternatively, the first feedback control may operate to modify a characteristic of impedance-matching components to increase or decrease the voltage or current delivered to the rectifying devices.

For example, the antenna elements may be embodied as shape-shifting antennas that change shape in response to an applied current or applied heat. For instance, the antennas, or components thereof, may comprise electromechanical shape-shifting antennas. The first feedback control may control the shape of the shape-shifting antennas to modify the conversion of EMR into an AC current. In one embodiment, the antenna feedback control may modify a dielectric constant of one or more of the antennas or antenna elements.

One or more antenna feedback controls may control the shape of one or more antennas to modify one of a resonance of an antenna, a Q-factor of an antenna, a dielectric constant of an antenna, an impedance of an antenna, a gain of an antenna, a beam shape of an antenna or antenna array, and/or a physical attribute of one or more antennas or antenna elements.

In addition to or instead of an antenna feedback control, an impedance feedback control may modify real or imaginary components of the impedance-matching components to modify the AC power delivered from the antennas to the rectifying devices. The impedance-matching components may be responsive to the impedance feedback control to limit the AC power throughput below a maximum value. For instance, one or more (or all) of the impedance matching components may be responsive to the impedance feedback control to dynamically varying impedance values. The impedance feedback control may modify a phase shift of one or more of the impedance-matching components.

The impedance-matching components may comprise tunable circuits that are responsive to the impedance feedback control. For example, the impedance feedback control may comprise an analog feedback loop that provides a signal to the tunable circuits of one or more of the impedance-matching components based on the output of the rectifying devices. The impedance feedback control may be operative to implement a target feedback response. For example, the impedance feedback control may be configure to (i) limit the AC power throughput below a maximum value, (ii) optimize (e.g., maximize) accepted AC power, (iii) optimize (e.g., minimize) reflected AC power, and/or (iv) optimize (e.g., minimize or modify) AC components generated by circuit components and/or the load (e.g., harmonics and/or other frequency components). Impedance and/or antenna feedback controls may modify characteristics of one or more antennas and/or impedance matching components to reflect (i.e., reject) power from or back to the one or more antennas.

Any of the various feedback controls described herein may be used to optimize various portions or components of the energy conversion process. For example, feedback controls may optimize generated harmonics by reducing or suppressing them. In contrast, feedback controls may optimize received EMR by maximizing a total output power, maintaining a power level below a threshold, maximizing an efficiency of power conversion, reducing reflected EMR, controlling temperature hotspots, etc. Accordingly, it can be understood that "optimizing" a particular element, device, characteristic, etc. may be "optimized" in a variety of ways depending on the specific targets and goals of the system. Some optimization targets can be generally assumed.

For example, optimizing noise in a system may generally be assumed to be a minimization or suppression process. In contrast, optimization of a DC-to-DC power conversion may, in some embodiments, include maximizing an efficiency of the transfer while, in other embodiments, include reducing reflections at the expense of efficiency. Various optimization strategies are described herein, and others can be understood in context. Examples of optimization strategies include maximizing efficiency, maintaining a value below a threshold, maximizing a total value, minimizing a value, controlling a value, controlling a distribution, minimizing reflections, minimizing harmonics, controlling harmonics, adjusting a power factor, suppressing generated AC components, and/or combinations or weighted functions thereof.

In various embodiments, the impedance-matching components comprise adaptive components. For example, the impedance-matching components may be tunable based on a feedback control signal, such as a digital or analog reflection feedback control signal. Examples of adaptive components responsive to feedback control signals include, for example, diodes, PIN diodes, transistors, varactors, limiter devices, mechanical switches, solid state relays, electronic switches, shape-changing devices, materials or devices with tunable dielectric constant, and/or materials and devices with tunable nonlinear power characteristics. In some embodiments, one or more of the antennas (or antenna elements) and/or impedance-matching components may comprise tunable metamaterial devices. In such embodiments, feedback control signals may tune the metamaterial devices.

The impedance feedback control may provide a biasing signal to one or more of the impedance-matching components. In some embodiments, the impedance feedback control may be an inherent feedback characteristic of the impedance-matching component. The impedance feedback control may operate to maximize or otherwise optimize power conversion efficiency, minimize or otherwise control temperature hotspots, prevent a power magnitude from exceeding a target value, stabilize output power, maintain a power output within a threshold range, minimize reflected power, minimize generated harmonics, or the like. In some embodiments, the number of antenna elements, the number of impedance-matching elements, and the number of rectifying devices may be the same. In such an embodiment, antenna and/or impedance feedback controls may comprise an equal number of feedback loops. That is, the system may include one (or more) feedback loop(s) for each free-space EMR to DC power component set (e.g., antenna, impedance-matching component, and rectifying device). The feedback loop may modify the antennas or impedance-matching components based on the output of each associated rectifying device.

In addition to or instead of an antenna feedback control and/or an impedance feedback control, a multi-timescale wireless rectification system may include a rectification feedback control to modify DC power delivered from the rectifying devices to the load by modifying a characteristic of the rectifying devices. The rectification feedback control may operate on a different timescale than the antenna feedback control and/or impedance feedback control. In some embodiments, a rectifying device may include one or more diodes, a switchable power divider network, a capacitor, a battery, an inductor, a transistor, a resistor, Zener diodes, thyristors, crowbar circuits, electronic relays, solid-state relays, electromechanical relays, or the like.

For example, the antenna and/or impedance feedback control(s) may operate very quickly (e.g., within nanoseconds, microseconds, or milliseconds) to modify the AC power delivered to the rectifying device(s). The rectification feedback control may operate on a slower timescale (e.g., tens or hundreds of milliseconds, or even seconds). The rectification feedback control may operate to maximize or otherwise optimize power conversion efficiency, minimize temperature hotspots, maintain temperatures below threshold values, prevent a power magnitude from exceeding a target value, stabilize output power, maintain a power output within a threshold range, minimize reflected power, minimize generated harmonics, or the like.

A multi-timescale wireless rectification system includes a DC feedback control to modify DC power delivered from the rectifying devices to the load. The DC feedback control may provide a feedback signal based on a load impedance, status of an energy storage device, load demand, expected load demand, or the like. The DC feedback control may modify a characteristic of a rectifier to modify the DC power delivered to the load. The DC feedback control may, alternatively or additionally, modify a characteristic of a DC-to-DC converter operating between the rectifier and the load. Similar to other feedback controls, the DC feedback control may operate to maximize or otherwise optimize power conversion efficiency, minimize or otherwise control temperature hotspots, maintain temperatures below threshold values, prevent a power magnitude from exceeding a target value, stabilize output power, maintain a power output within a threshold range, minimize reflected power, minimize generated harmonics, or the like.

The DC feedback control may operate to modify (increase or decrease) a DC voltage delivered to a load. The DC feedback control may operate to modify a DC current delivered to a load. The DC feedback control may operate to modify a total DC power delivered to a load. For instance, a multi-timescale wireless rectification system may comprise a DC-to-DC pulse width modulation controller. The DC feedback control may drive the pulse width modulation controller.

In other embodiments, the DC feedback control may modify an input or output impedance of the DC-to-DC converter. The DC feedback control may operate to maintain a constant input and/or output impedance of the DC-to-DC converter. The DC feedback control may adjust rectifiers and/or DC-to-DC converters to maintain a constant or smoother DC power output. The DC-to-DC converter may comprise a maximum power point tracking (MPPT) controller. The MPPT may operate to maintain a DC voltage and/or current levels at a maximum total output power, maximize power efficiency, minimize heating, maintain a voltage above a threshold minimum, maintain a current level within a bounded threshold, or the like. The DC feedback control may operate to modify a target or goal of the MPPT controller. The DC feedback control may operate to modify the input and/or output impedance of the MPPT controller.

In various embodiments, the DC feedback control may comprise one or more analog or digital feedback loops. The DC feedback control may, for example, comprise a digital controller (e.g., a field-programmable gate array (FPGA), a microcontroller or microprocessor). The digital controller may receive one or more inputs and, in response, drive one or more rectifiers and/or DC-to-DC converters. For example, the digital controller may receive values from sensors (e.g., voltage and/or current sensors) and/or external data sources.

In another example, other components and/or processors of the UAV may indicate future power demand to the digital controller. The digital controller may provide a DC feedback control to drive the DC-to-DC converter in response to the indicated future power demand. In another embodiment, the wireless power transmitter may communicate a future increase or decrease in power availability. The digital controller may transmit a DC feedback control to drive the DC-to-DC converter(s) and/or rectifier(s) in response to the anticipated change in power availability.

In some embodiments, the DC feedback control may operate to bias a gate voltage of one or more transistors. The DC feedback control may operate to bias a voltage of one or more inputs of one or more transistors to optimize power output. The optimization may, for example, include maximizing the power output. In still other embodiments, the antennas and rectifying devices may be embodied as rectennas, or even as tunable rectennas. In such an embodiment, the DC feedback control may operate to tune the rectennas to modify the DC output of the rectennas.

In some embodiments, the system may include more than one DC feedback control. One DC feedback control may operate to modify or tune a rectenna. One or more additional DC feedback controls may operate to modify one or more of rectifiers, DC-to-DC buck or boost converters, MPPTs, or one of a variety of DC-to-DC converters. The various DC feedback controls may operate on different timescales and in response to different inputs.

The DC output may be adjusted based on the type of load. The load, for example, may comprise batteries of various types that require various charge profiles at various voltages. For example, the DC output may be modified based on the state of charge (SOC) percentage and a known battery type to safely and fully charge a battery of a particular composition. The DC feedback control may modify DC outputs based on detected or measured values associated with alternative storage devices, such as capacitive inductive, or mechanical energy storage devices.

In still other embodiments, the DC output may be modified to support one or more alternative or additional loads, such as propulsion devices, lights, sensors, ultrasound transmitters, ultrasound receivers, electromagnetic transmitters, LiDAR sensors, data processing devices, boost converters, buck converters, buck-boost converters, single-ended primary-inductor converters (SEPICs), and/or flyback converters.

In some embodiments, a multi-timescale wireless rectification system may include a load controller to dynamically add or shed load. In some embodiments, the load controller may operate based on a feedback control signal to adjust the amount or type of load based on available power, expected future power availability, a received signal indicating future power availability, energy storage capacity, motor power demand, and/or another system status change. The load controller may be embodied as a programmable digital logic element, programmable digital logic, a field-programmable gate array (FPGA), an analog feedback loop, or other dynamic feedback system.

The load controller may operate on a feedback control operating a different timescale than other timescales. The timescale for the feedback control for the load controller may operate in response to voltage drops and/or detected current shortages. In other embodiments, the timescale for the feedback control for the load controller may operate on an anticipatory basis. That is, the load controller may add or shed load based on expected power availability.

The load controller may operate in combination with DC power combiners and/or DC-to-DC converters. Any of the various feedback controls may be based, at least in part, on power measurements, temperature measurements, current measurements, voltage measurements, and/or other sensor readings.

Components of a receiver may be adapted based on the frequency used for EMR power transmission. For example, components for radio frequencies (RF) may be different than those used for optical or infrared frequencies. Examples of possible frequency bands include those in the industrial, scientific and medical (ISM) radio band, <NUM>, <NUM>, <NUM>, optical frequencies, and infrared frequencies. Specific frequency bands may be more suitable for different power levels, transmission distances, line-of-sight applications, through-object applications, etc. Moreover, specific frequency bands may be utilized to comply with government regulations, to limit interference with other equipment, and/or to otherwise conform to the specifications of a particular application or use-case.

Many existing computing devices and infrastructures may be used in combination with the presently described systems and methods. Some of the infrastructure that can be used with embodiments disclosed herein is already available, such as general-purpose computers, computer programming tools and techniques, digital storage media, and communication links. Many of the systems, subsystems, modules, components, and the like that are described herein may be implemented as hardware, firmware, and/or software. Various systems, subsystems, modules, and components are described in terms of the function(s) they perform because such a wide variety of possible implementations exist. For example, it is appreciated that many existing programming languages, hardware devices, frequency bands, circuits, software platforms, networking infrastructures, and/or data stores may be utilized alone or in combination to implement a specific function.

As used herein, a computing device, system, subsystem, module, or controller may include a processor, such as a microprocessor, a microcontroller, logic circuitry, or the like. A processor may include one or more special-purpose processing devices, such as application-specific integrated circuits (ASICs), programmable array logic (PAL), programmable logic array (PLA), programmable logic device (PLD), field-programmable gate array (FPGA), or other customizable and/or programmable device. The computing device may also include a machine-readable storage device, such as non-volatile memory, static RAM, dynamic RAM, ROM, CD-ROM, disk, tape, magnetic, optical, flash memory, or another machine-readable storage medium. Various aspects of certain embodiments may be implemented using hardware, software, firmware, or a combination thereof.

<FIG> illustrates an example of an unmanned aerial vehicle (UAV) <NUM> with a tunable multi-timescale wireless rectification system as part of an EMR receiver <NUM> for receiving wireless power, according to one embodiment. The illustrated UAV <NUM> is a quadcopter with four discrete motors <NUM> and associated rotors <NUM>. It is appreciated that any of a wide variety of UAVs may utilize the systems and methods described herein, including fixed-wing UAVs, vertical take-off and landing (VTOL) UAVs, helicopters, hexacopter, octocopters, and n-copter devices with any number of discrete rotors, propellers, stabilizers, or other propulsion or lift devices.

In the illustrated embodiment, the EMR receiver <NUM> is rectangular, and the multi-element nature of the EMR receiver <NUM> is represented by the grid of square elements. It is appreciated that the EMR receiver <NUM> may be any shape, size, or thickness, and may have elements that face in directions other than straight down. In some embodiments, the EMR receiver pivots and/or rotates to maximize or otherwise optimize a power characteristic, as described herein.

<FIG> illustrates a wireless power transmitter <NUM> transmitting wireless power to a mobile UAV <NUM> fitted or retrofitted with an EMR receiver <NUM> for receiving EMR and converting the received EMR into an electric current, according to various embodiments. The wireless power transmitter <NUM> may be part of a network of wireless power transmitters. Each of the wireless power transmitters in the network of wireless power transmitters may generate a steerable wireless beam to the UAV <NUM> as it moves. The EMR receiver <NUM> may be embodied as multi-timescale wireless rectification system, according to any combination of the various embodiments described herein.

<FIG> illustrates a packaged computer chip <NUM> with a small EMR receiver <NUM> affixed thereto. The EMR receiver <NUM> may supply a DC electric current to the computer chip <NUM> by converting EMR received from an EMR transmitter according to any of the various embodiments described herein. The EMR receiver <NUM> may be embodied as a multi-timescale wireless rectification system, according to any combination of the various embodiments described herein.

<FIG> illustrates a user <NUM> of a mobile phone <NUM>. The user <NUM> may retrofit a case of the mobile phone <NUM> with an EMR receiver <NUM> to receive wireless power. Alternatively, the EMR receiver <NUM> may be integrated within the mobile phone <NUM> by, for example, the manufacturer of the mobile phone <NUM> or manufacturer of the power supply or power storage device of the mobile phone <NUM>.

Any of a wide variety of devices may be fitted, configured with, retrofitted with, or manufactured with integral EMR receivers to receive EMR from mobile and/or stationary power transmitters. Examples of devices include, but are not limited to, mobile phones, tablet computing devices, wearable tech devices, watches, laptop computers, unmanned aerial vehicles (UAVs), mobile battery storage devices, robots, automobiles, busses, laptops, computer peripheral devices, and other mobile or stationary devices that consume electricity. The EMR receiver <NUM> may be embodied as any combination of the various embodiments of tunable multi-timescale wireless rectification systems for receiving wireless power described herein.

<FIG> illustrates a simplified block diagram of a wireless rectification system <NUM> for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>. Various power consuming devices and/or power storage devices may be described as a single load or as loads <NUM>. An antenna <NUM> may receive the EMR <NUM>. An impedance-matching component <NUM> may provide input and/or output impedance matching for controlling the AC current delivered from the antenna <NUM> to the rectifying device <NUM>. The rectifying device <NUM> may convert the AC power to DC power utilizing any of a wide variety of circuits, controllers, discrete electrical components, and the like. The rectifying device <NUM> may be embodied as any of a wide variety of rectifying devices known in the art.

A DC-to-DC converter <NUM> may modify DC power produced by the rectifying device <NUM> for delivery of DC power to the load <NUM>. In <FIG>, and in various other illustrated embodiments of this disclosure, the antenna <NUM>, the impedance-matching component <NUM>, the rectifying device <NUM>, and the DC-to-DC converter <NUM> are shown as separate components in electrical communication with one another. In other embodiments, one or more of the antenna <NUM>, the impedance-matching component <NUM>, the rectifying device <NUM>, and/or the DC-to-DC converter <NUM> may be combined as a single component, packaged together, and/or configured to provide overlapping functions. In still other embodiments, one or more of the antenna <NUM>, the impedance-matching component <NUM>, the rectifying device <NUM>, and/or the DC-to-DC converter <NUM> may be divided into sub-components.

The tunable multi-timescale wireless rectification system, according to any combination of the various embodiments described herein, may be utilized in conjunction with the illustrated wireless rectification system <NUM>. For example, a tunable multi-timescale wireless rectification system may be used to improve, protect, or otherwise control the conversion of EMR <NUM> to DC power for the load <NUM> by the wireless rectification system <NUM>.

<FIG> illustrates another simplified block diagram of a wireless rectification system <NUM> for converting EMR <NUM> into DC power for consumption by a load <NUM>, according to one embodiment. In the illustrated embodiments, an antenna(s) block <NUM> represents any of a wide variety of antenna types for receiving beamformed wireless EMR <NUM> from a wireless power transmitter. An impedance-matching component(s) block <NUM> represents any number or type of impedance-matching components for electrically connecting any number of antennas <NUM> to one or more rectifying devices <NUM>. Any number of DC-to-DC converters <NUM> may connect the one or more rectifying devices <NUM> to one or more loads <NUM>.

The wireless rectification system <NUM> may include multiple antennas <NUM>, rectifying devices <NUM>, impedance-matching components <NUM>, and DC-to-DC converters <NUM>. The numbers of each of these components may be <NUM>:<NUM>:<NUM>:<NUM> or many to one (e.g., W:X:Y:Z, where W, X, Y, and Z are integer values). The wireless rectification system <NUM> may provide power to any of a wide variety of loads <NUM>, including energy storage loads (e.g., capacitors, batteries, etc.) and power consuming loads (e.g., propulsion/lift components, sensors, processors, etc.).

<FIG> illustrates another simplified block diagram of a wireless rectification system for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>, according to one embodiment. The illustrated embodiment shows multiple antennas <NUM>, impedance-matching components <NUM>, rectifying devices <NUM>, and DC-to-DC converters <NUM>. Optionally, one or more DC combiners <NUM> may connect the output of the DC-to-DC converters <NUM> to the load <NUM>. <FIG> is an example of a wireless rectification system <NUM> with <NUM>:<NUM> component ratios of various components. Any of the various tunable multi-timescale wireless rectification systems, or combinations thereof, may be used to enhance the functionality of the illustrated wireless rectification system <NUM>.

<FIG> illustrates another simplified block diagram of a wireless rectification system <NUM> for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>. A single rectifying device <NUM> receives impedance-matched AC power from the antennas <NUM> via the impedance-matching components <NUM>. A DC-to-DC converter <NUM> provides modified power between the rectifying device <NUM> and the load(s) <NUM>. Any of the various tunable multi-timescale wireless rectification systems, or combinations thereof, may be used to enhance the functionality of the wireless rectification system <NUM> in <FIG>.

<FIG> illustrates another simplified block diagram of a wireless rectification system for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>. An
array of antennas <NUM> (or antenna elements of a single antenna) receive EMR <NUM>. An impedance-matching component <NUM> delivers modified AC power from the antennas <NUM> to a rectifying device <NUM>. DC-to-DC converter <NUM>, according to any of the various DC-to-DC converter embodiments described herein, may provide the rectified power to the load(s) <NUM>. Any of the various tunable multi-timescale wireless rectification systems, or combinations thereof, may be used to enhance the functionality of the wireless rectification system in <FIG>.

<FIG> illustrates another simplified block diagram of another wireless rectification system for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>. A plurality of antennas <NUM> converts EMR <NUM>, such as free-space EMR, to an AC current for conversion to DC power by the rectifying device <NUM>. A DC-to-DC converter <NUM> may modify the DC power for delivery to the load(s) <NUM>. Again, any of the various tunable multi-timescale wireless rectification systems, or combinations thereof, may be used to enhance the functionality of the wireless rectification system in <FIG>.

<FIG> illustrates a simplified block diagram of a feedback-controlled wireless rectification system <NUM> for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>, according to another embodiment. Any number of antennas <NUM> may receive EMR <NUM>. The antennas <NUM> may function together as a beamforming array, or as individual receivers for receiving EMR from one or more transmitters. A number of impedance-matching components <NUM> may be less than, equal to, or more than the number of antennas <NUM>. The impedance-matching components <NUM> may provide impedance matching of the antennas <NUM> to any number of rectifying devices <NUM>. The number of rectifying devices <NUM> may be more than, less than, or equal to the number of antennas <NUM> and/or impedance-matching components <NUM>. The rectifying devices <NUM> may deliver DC power to one or more DC-to-DC converters <NUM> for power delivery to the load <NUM>.

The wireless rectification system <NUM> may be feedback-controlled in that a feedback circuit or feedback controller (antenna feedback control <NUM>) may be responsive to a power characteristic of the AC power between the impedance-matching component(s) <NUM> and the rectifying device(s) <NUM>, the DC power between the rectifying device(s) <NUM> and the DC-to-DC converter(s) <NUM>, and/or the DC power delivered to the load(s) <NUM>. For example, power may be considered to flow forward from the antenna(s) <NUM> to the impedance-matching component(s) <NUM>, and on to the rectifying device(s) <NUM>. In some instances, the power may be considered to flow backward from the impedance-matching component(s) <NUM> to the antenna(s) <NUM> and/or from the rectifying device(s) <NUM> to the impedance matching component(s) <NUM>. The antenna feedback control 825may be responsive to power flowing forward, backward, or in different directions between different elements at a given instant or during a time period.

In some instances, the frequency of the AC power flowing between the impedance-matching component(s) <NUM> and the rectifying device(s) <NUM> may be at the original frequency of the EMR <NUM> received by the antenna(s) <NUM>. In other embodiments, the frequency may be at a harmonic of the frequency of the EMR <NUM> received by the antenna(s) <NUM>. The antenna feedback control <NUM> may be responsive to, suppress, and/or otherwise harmonic power flow between the various elements depicted in <FIG>, such as harmonics that may contribute to parasitic backscatter modulation.

The antenna feedback control <NUM> may, for example, operate to reduce, suppress, or modify harmonics generated by, for example, the rectifying device(s) <NUM>, created or reflected by the load <NUM>, by operation of the DC-DC converter(s) <NUM>, or other reflected or created distortion to the primary power flow. The antenna feedback control <NUM>, may operate to reduce, suppress, or otherwise modify harmonics generated by the antenna(s) <NUM>, the impedance-matching component(s) <NUM>, the rectifying device(s) <NUM>, and/or the DC-to-DC converter <NUM>, and/or the load <NUM>.

The antenna feedback control <NUM> may tune or otherwise modify one or more characteristics of the antenna(s) <NUM>. For example, the antenna feedback control <NUM> may control the shape, modify a resonance, modify a Q-factor, modify a dielectric constant, modify the impedance, modify a gain, modify a beam shape, and/or modify a physical attribute of one or more of the antennas <NUM>.

The antenna feedback control <NUM> may be responsive to more than one monitored characteristic of the downstream power. In various embodiments, the antenna feedback control <NUM> may be responsive to multiple monitored characteristics on different timescales. For example, the antenna feedback control <NUM> may respond to changes in the AC power between the impedance-matching components <NUM> and the rectifying devices <NUM> on a microsecond or millisecond timescale. The antenna feedback control <NUM> may respond to changes in the DC power output of the rectifying devices <NUM>, but on a slower timescale. Similarly, the antenna feedback control <NUM> may additionally or alternatively respond to measured characteristics of the DC power delivered to the load(s) <NUM> on an even timescale.

<FIG> illustrates a simplified block diagram of a feedback-controlled wireless rectification system <NUM> for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>, according to another embodiment. Any number of antennas <NUM> may receive EMR <NUM>. A number of impedance-matching components <NUM> may provide impedance matching of the antenna(s) <NUM> to any number of rectifying devices <NUM>. The rectifying device(s) <NUM> may deliver DC power to one or more DC-to-DC converters <NUM> for power delivery to the load(s) <NUM>.

An impedance feedback control <NUM> may be responsive to a power characteristic of the AC power from the antennas <NUM> on a first timescale. The impedance feedback control <NUM> may additionally or alternatively be responsive to a power characteristic of the AC power between the impedance matching components <NUM> and the rectifying devices <NUM>. The impedance feedback control <NUM> may be responsive to the DC power output of the rectifying device(s) <NUM> and/or the DC power delivered to the load(s) <NUM>.

The impedance feedback control <NUM> may tune or otherwise modify one or more characteristics of the impedance-matching component(s) <NUM>, as described herein. As in previous embodiments, the rectification system <NUM> may include any number of antennas <NUM>, impedance-matching components <NUM>, rectifying devices <NUM>, and DC-to-DC converters <NUM>. In some embodiments, impedance-matching components <NUM> and/or DC-to-DC converters <NUM> may be omitted. The tunable multi-timescale wireless rectification system <NUM> may include a plurality of impedance feedback controls <NUM>. For example, the tunable multi-timescale wireless rectification system <NUM> may include a unique impedance feedback control <NUM> for each impedance-matching component <NUM>. Each impedance feedback control <NUM> may be responsive to multiple measured characteristics or a single measured characteristic. The impedance feedback control <NUM> may be responsive to various measured characteristics on different timescales.

<FIG> illustrates a simplified block diagram of a feedback-controlled wireless rectification system <NUM> for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>, according to another embodiment. As illustrated, a rectifier feedback control <NUM> may be responsive to AC or DC power characteristics from various locations with the wireless rectification system. The rectifier feedback control <NUM> may tune or modify the rectification of AC power to DC power by the rectifying device(s) <NUM>. For example, the rectifier feedback control <NUM> may modify an input impedance of the rectifying device(s) <NUM>, an output impedance of the rectifying device(s) <NUM>, a voltage output of the rectifying device(s) <NUM>, a current of the rectifying device(s) <NUM>, or other output or input characteristic of the rectifying device(s) <NUM>.

The manner in which the rectifier feedback control <NUM> modifies the rectifying device(s) <NUM> may depend on which monitored location of the wireless rectification system <NUM> the rectifier feedback control <NUM> is responding to at a given time. The timescale of each response may vary, and the rectifier feedback control <NUM> may include control logic to analyze and respond to some monitored power characteristics on a relatively slow timescale and discrete electronic components to respond to another monitored power characteristic on a very short (i.e., fast) timescale.

<FIG> illustrates a simplified block diagram of another feedback-controlled wireless rectification system <NUM> for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>, according to another embodiment. <FIG> is similar to <FIG>, but includes a DC feedback control <NUM> that modifies one or more characteristics of DC-to-DC converters <NUM> in response to AC or DC characteristics at other locations within the wireless rectification system <NUM> on various timescales. As in other embodiments, the tunable multi-timescale wireless rectification system <NUM> may include a DC feedback control <NUM> for each DC-to-DC converter <NUM> in the rectification system. In other embodiments, a single DC feedback control <NUM> circuit or controller may tune or otherwise control the output (or input impedance) of multiple DC-to-DC converters <NUM>.

<FIG> illustrates a simplified block diagram of another feedback-controlled wireless rectification system <NUM> for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>, according to another embodiment. The illustrated embodiment includes a multi-timescale feedback control <NUM> that includes an antenna feedback control, an impedance feedback control, a rectifying feedback control, and a DC feedback control. The multi-timescale feedback control <NUM> may provide control inputs to one or more antennas <NUM>, impedance matching components <NUM>, rectifying devices <NUM>, and/or DC-to-DC converters <NUM>. The control inputs may be provided on the same timescale, but may be responsive to inputs from various locations within the wireless rectification system <NUM> on varying timescales.

In other embodiments, multi-timescale feedback control <NUM> may be responsive to the various control inputs on the same timescale (e.g., via constant measurements), but control one or more of the antennas <NUM>, impedance-matching components <NUM>, rectifying devices <NUM>, and DC-to-DC converters <NUM> on varying timescales. For example, the multi-timescale feedback control <NUM> may modify characteristics of the antenna(s) <NUM> on a first timescale, the impedance-matching component(s) <NUM> on a second timescale, the rectifying device(s) <NUM> on a third timescale, and the DC-to-DC converter(s) <NUM> on a fourth timescale.

In some embodiments, the first, second, third, and fourth timescales may be different than one another. For example, each successively named timescale may be longer than the previous timescale. In other embodiments, a controller may allow for dynamic customization of each of the first, second, third, and fourth timescales. In still other embodiments, each of the first, second, third, and fourth timescales may be configured to have a static or quasi-static response time based on a particular application.

<FIG> illustrates a simplified block diagram of a tunable multi-timescale wireless rectification system <NUM> similar to that of <FIG> for converting EMR <NUM> into DC power for consumption by one or more loads <NUM>, according to another embodiment. In the illustrated embodiment, the tunable multi-timescale wireless rectification system <NUM> further includes a feedback controller <NUM> to control or dynamically modify the feedback controls sent to the antenna(s) <NUM>, the impedance-matching component(s) <NUM>, the rectifying device(s) <NUM>, and the DC-to-DC converter(s) <NUM>. The feedback controller <NUM> may include or be in communication with a load monitor and controller <NUM>.

The load monitor and controller <NUM> may be responsive to the feedback controller <NUM> based on measured power characteristics of AC power between the antenna(s) <NUM> and the impedance-matching component(s) <NUM>, or between the impedance-matching component(s) <NUM> and the rectifying device(s) <NUM>. The load monitor and controller <NUM> may be responsive to the measured AC or DC power at various locations relative to the antenna(s) <NUM>, impedance-matching component(s), <NUM>, rectifying device(s) <NUM>, and/or DC-to-DC converter(s) <NUM>.

Optionally, the load monitor and controller <NUM> may be responsive on a different timescale from the various multi-timescale feedback controls <NUM>. The load monitor and controller <NUM> may dynamically shed or add load(s) <NUM> based on measured power characteristics. The load monitor and controller <NUM>, for example, may direct a UAV to decrease power consumption based on feedback controls indicating that less power may be available in the immediate future. In some embodiments, the load monitor and controller <NUM> may direct power into and out of storage devices to compensate for excess energy or energy shortages.

<FIG> illustrates another simplified block diagram of a tunable multi-timescale wireless rectification system <NUM>, according to one embodiment. In the illustrated embodiment, free-space EMR <NUM> is received by antenna(s) <NUM>. Impedance-matching component(s) <NUM> convey AC power from the antenna(s) <NUM> to rectifying devices <NUM>. The rectifying devices <NUM> convert the AC power into DC power for delivery to, in some embodiments, DC-to-DC converters <NUM>. The DC-to-DC converters <NUM> convey DC power to the load(s) <NUM>. As previously described, the load(s) <NUM> may include various consuming devices and/or energy storage devices.

The tunable multi-timescale wireless rectification system <NUM> may include one, two, three, or all four of the illustrated feedback controls. Specifically, the tunable multi-timescale wireless rectification system <NUM> may include an antenna feedback control <NUM>, an impedance feedback control <NUM>, a rectifying feedback control <NUM>, and/or a DC feedback control <NUM>. In the illustrated embodiment, the antenna feedback control <NUM> may modify a characteristic of one or more of the antennas <NUM> in response to measured output values of one or more of the antennas <NUM> on a first timescale. The impedance feedback control <NUM> may modify a characteristic of one or more off the impedance-matching components <NUM> based on output values of one or more of the impedance-matching components <NUM> on a second timescale. The rectifying feedback control <NUM> may modify a characteristic of one or more rectifying devices <NUM> based on output values of one or more of the rectifying devices <NUM> on a third timescale. The DC feedback control <NUM> may modify a characteristic of one or more DC-to-DC converters <NUM> based on output values of one or more of the DC-to-DC converters <NUM> and/or consumption characteristics of the load(s) <NUM>. The first, second, third, and fourth timescales may be slightly different from one another or may be different by orders of magnitude.

<FIG> illustrates another simplified block diagram of a tunable multi-timescale wireless rectification system <NUM>, according to one embodiment. As compared to <FIG>, the tunable multi-timescale wireless rectification system <NUM> includes multiple feedback controls in communication with one another. Thus, the embodiment in <FIG>, includes an antenna feedback control <NUM> that may modify a characteristic of one or more of the antennas <NUM> in response to measured output values of one or more of the antennas <NUM> on a first timescale and/or measured values from the outputs of the impedance-matching component(s) <NUM>, rectifying device(s) <NUM>, and/or DC-to-DC converter(s) <NUM> on various different timescales.

The impedance feedback control <NUM> may modify a characteristic of one or more of the impedance-matching components <NUM> based on output values of one or more of the impedance-matching components <NUM> on a second timescale and/or measured downstream values of the outputs of the rectifying device(s) <NUM> and/or the DC-to-DC converter(s) <NUM> on various other timescales.

The rectifying feedback control <NUM> may modify a characteristic of one or more rectifying devices <NUM> based on output values of one or more of the rectifying devices <NUM> on a third timescale and/or the output of the DC-to-DC converter <NUM> outputs on a different timescale.

<FIG> illustrates another simplified block diagram of a tunable multi-timescale wireless rectification system <NUM>, according to another embodiment. In the illustrated embodiment, each of the feedback controls includes bi-directional communication to allow for each feedback control to control a component of the wireless rectification system <NUM> on various timescales in response to one or more power or impedance characteristics at one or more locations along the rectification path.

<FIG> illustrates another simplified block diagram of a tunable multi-timescale wireless rectification system <NUM>, according to yet another embodiment. In the illustrated embodiment, the tunable multi-timescale wireless rectification system <NUM> may include one or more of the feedback controls that may be further responsive to a data stream (shown as a DS box) received from a wireless power transmitter <NUM> that transmits both the wireless power signal <NUM> and a data stream signal <NUM> from a data stream component <NUM>. The data stream signal <NUM> may be out-of-band relative to the wireless power signal <NUM>.

As an example, the data stream signal <NUM> may provide an indication to the antenna feedback control <NUM> that the wireless power signal <NUM> will switch frequencies at a prescribed time. The antenna feedback control <NUM> may respond to this information on a suitable timescale to modify a tuning, matching, Q-factor, beam shape, frequency response, resonance, physical shape, impedance, and/or another antenna characteristic. In some embodiments, the data stream signal <NUM> may contain information indicating an expected increase or decrease in available power. The various feedback controls (<NUM>, <NUM>, <NUM>, and/or <NUM>) may respond to the expected change in available power by modifying characteristics of the antenna(s) <NUM>, impedance-matching component(s) <NUM>, rectifying device(s) <NUM>, and/or DC-to-DC converter(s) <NUM>.

In some embodiments, the data stream signal <NUM> may provide instructions to adjust the time scales of one or more of the feedback controls <NUM>, <NUM>, <NUM>, and/or <NUM>. For example, the wireless rectification system <NUM> may be apprised of potential future instability of the power signal <NUM>. The feedback controls may be responsive to this information from the data stream signal <NUM> by increasing the speed of the feedback control loops to more quickly adjust to the expected, less stable power signal <NUM>.

In some embodiments, the wireless power transmitter <NUM> may communicate a data stream signal <NUM> with a load monitor and/or controller, such as the load monitor and controller <NUM> in <FIG>, to modify usage and/or storage characteristics of the load. A similar load monitor and/or controller may be configured to function in conjunction with the tunable multi-timescale wireless rectification system <NUM>.

<FIG> illustrates a more simplified block diagram of a tunable multi-timescale wireless rectification system that includes an antenna feedback control <NUM> and a DC feedback control <NUM>. As illustrated, an antenna <NUM> may receive EMR <NUM> and convert the received EMR <NUM> into an AC current. The AC current may be received by a rectifying device <NUM> for conversion to a DC current. The antenna feedback control <NUM> may be responsive, on a first timescale, to a measured characteristic of the DC power (e.g., a voltage, current, or total power output of the rectifying device <NUM>). The antenna feedback control <NUM> may modify a characteristic of the antenna <NUM> based on the measured characteristic of the DC power.

A DC-to-DC converter <NUM> modifies the DC power delivered from the rectifying device <NUM> to the load(s) <NUM>. A DC feedback control <NUM> controls or modifies the functionality of the DC-to-DC converter <NUM> based on a monitored output of the DC-to-DC converter <NUM> and/or information from a load monitor <NUM>. For example, a load monitor <NUM> may monitor the immediate power consumption of the load(s) <NUM>, determine a future power consumption by the load(s) <NUM>, control the power consumption of the load(s) <NUM>, and/or otherwise be able to communicate load information. The DC feedback control <NUM> utilizes the load information to modify the DC-to-DC converter <NUM> on a second timescale. The first timescale is an order of magnitude shorter than the second timescale. For example, the antenna feedback control <NUM> may modify characteristics of the antenna <NUM> on a tens-of-milliseconds timescale, while the DC feedback control <NUM> may modify characteristics of the DC-to-DC converter <NUM> on a hundreds-of-milliseconds timescale.

<FIG> illustrates another simplified block diagram of a tunable multi-timescale wireless rectification system, according to another embodiment. In the illustrated embodiment, an antenna <NUM> receives EMR <NUM>, such as free-space EMR from a wireless transmitter. An impedance-matching component <NUM> may provide impedance matching between the antenna <NUM> and a rectifying device <NUM>. The rectifying device <NUM> may convert AC power from the antenna <NUM> to DC power. The DC power may be modified by a DC-to-DC converter <NUM> for delivery to one or more load(s) <NUM>.

Claim 1:
A tunable multi-timescale wireless rectification system, comprising:
a plurality of antennas to receive electromagnetic radiation;
a plurality of rectifying devices to produce DC power outputs;
a plurality of impedance-matching components to couple each of the antennas to at least one of the rectifying devices;
a plurality of DC-to-DC converters to couple the rectifying devices to a load;
a first feedback control associated with at least one of (i) the antennas and (ii) the impedance-matching components to modify AC power delivered from the antennas to the rectifying devices on a first timescale; and
a second feedback control associated with the DC-to-DC converters to modify DC power delivered from the rectifying devices to the load on a second timescale, wherein the first timescale is an order of magnitude shorter than the second timescale.