Patent Application
20170256991
Wireless power transmission systems may rely on electronic circuits such as rectifiers, AC (Alternating Current) to DC (Direct Current) converters, impedance matching circuits, and other power electronics to condition, monitor, maintain, and/or modify the characteristics of the voltage and/or current used to provide power to electronic devices. Power electronics can provide power to a load with dynamic input impedance characteristics. In some cases, in order to enable efficient power transfer, a dynamic impedance matching network is provided to match varying load impedances to that of the power source.
In some applications, impedances within a wireless power system may vary dynamically. In such applications, for example, impedance matching between a load, such as a resonator coil, and a power supply of the apparatus may be required to prevent unnecessary energy losses and excess heat. Accordingly, power transfer systems transferring and/or receiving power via highly resonant wireless energy transfer, for example, may be required to configure or modify impedance matching networks to maintain efficient power transfer.
Embodiments provided herein describe methods and apparatus for detecting cross-connection in a wireless energy transfer system. Embodiments can include controlling current to a transmit coil of a power transmitter unit (PTU) to include perturbations having current level increases for selected durations of time and/or current level decreases for selected durations of time. The perturbed signal from the PTU can be received by a power receiving unit (PRU), which can transmit signal data derived from a receive coil of the PRU to the PTU. The PTU can be configured to interact with the PRU via an in-band wireless energy transfer channel and/or an out-of-band wireless communication channel. In embodiments, the data derived from the receive coil is transmitted by the PRU to the PTU via the out-of-band communication channel. The data received by the PTU can be processed to determine a level of correlation between the signal perturbations transmitted by the PTU transmit coil and the data from the PRU to determine a cross-connection, in other words, if the PRU is communicating with a PTU it is not coupled to for the purposes of wireless power reception. If so, the PRU can be disconnected from the unintended PTU. In embodiments, the disconnected PRU can be blacklisted by the PTU to prevent immediate reconnection that re-establishes a cross-connect condition.
In one aspect of the invention, a method comprises: transmitting first data from a power transmitter unit (PTU), via a first channel, by controlling a transmission parameter to a transmit coil of the PTU; receiving at the PTU, via a second channel, second data from a power receiving unit (PRU); and processing the received second data to determine a level of correlation between the first data and the second data to determine if the PRU is connected to the PTU.
The method can include one or more of the following features: controlling a transmission parameter comprises modulating the transmission parameter, the transmission parameter comprises a current, voltage, and/or power, modulating the transmission parameter includes increases and decreases of a level of the transmission parameter for selected durations of time, disconnecting the PRU from the PTU, blacklisting the disconnected PRU, the received data is indicative of rectified voltage of the PRU, the first channel is an in-band wireless power transfer channel, the second channel is an out-of-band wireless communication channel, the level of correlation is determined by calculating a derivative of the received data, an amplitude of the derivative is determined, a direction of the derivative is determined, and/or a timing of the derivative is determined.
In another aspect of the invention, a system comprises: a power transmitter unit (PTU) configured to transmit first data via a first channel by controlling a transmission parameter to a transmit coil of the PTU, and to receive via a second channel second data from a power receiving unit (PRU); and a processor module configured to process the received second data to determine a level of correlation between the first data and the second data to determine if the PRU is connected to the PTU.
The system can include one or more of the following features: modulating the transmission parameter, the transmission parameter comprises a current, voltage, and/or power, modulating the transmission parameter includes increases and decreases of a level of the transmission parameter for selected durations of time, disconnecting the PRU from the PTU, blacklisting the disconnected PRU, the received data is indicative of rectified voltage of the PRU, the first channel is an in-band wireless power transfer channel, the second channel is an out-of-band wireless communication channel, the level of correlation is determined by calculating a derivative of the received data, an amplitude of the derivative is determined, a direction of the derivative is determined, and/or a timing of the derivative is determined.
In a further aspect of the invention, a system comprises: a power transmitter unit (PTU) configured to transmit first data via a first channel, by controlling a transmission parameter to a transmit coil of the PTU, and to receive via a second channel, second data from a power receiving unit (PRU); and a means for cross-connect detection for processing the received second data to determine a level of correlation between the first data and the second data to determine if the PRU is connected to the PTU.
The system can further include one or more of the following features: controlling a transmission parameter comprises modulating the transmission parameter, the transmission parameter comprises a current, voltage, and/or power, modulating the transmission parameter includes increases and decreases of a level of the transmission parameter for selected durations of time, disconnecting the PRU from the PTU, blacklisting the disconnected PRU, the received data is indicative of rectified voltage of the PRU, the first channel is an in-band wireless power transfer channel, the second channel is an out-of-band wireless communication channel, the level of correlation is determined by calculating a derivative of the received data, an amplitude of the derivative is determined, a direction of the derivative is determined, and/or a timing of the derivative is determined.
The impedance matching networks (IMNs) 108, 112 can be designed to maximize the power delivered to the load 114 at a desired frequency (e.g., 80-90 kHz, 100-200 kHz, 6.78 MHz) or to maximize power transfer efficiency. The impedance matching components in the IMNs 108, 112 can be chosen and connected so as to preserve a high-quality factor (Q) value of resonators 106, 110. Depending on the operating conditions, the components in the IMNs 108, 112 can be tuned to control the power delivered from the power supply to the load 114, for example, to maximize efficient wireless transmission of power.
The IMNs' (108, 112) components can include, for example, a capacitor or networks of capacitors, an inductor or networks of inductors, or various combinations of capacitors, inductors, diodes, switches, and resistors. The components of the IMNs can be adjustable and/or variable and can be controlled to affect the efficiency and operating point of the system. Impedance matching can be performed by varying capacitance, varying inductance, controlling the connection point of the resonator, adjusting the permeability of a magnetic material, controlling a bias field, adjusting the frequency of excitation, and the like. The impedance matching can use or include any number or combination of varactors, varactor arrays, switched elements, capacitor banks, switched and tunable elements, reverse bias diodes, air gap capacitors, compression capacitors, barium zirconium titanate (BZT) electrically tuned capacitors, microelectromechanical systems (MEMS)-tunable capacitors, voltage variable dielectrics, transformer coupled tuning circuits, and the like. The variable components can be mechanically tuned, thermally tuned, electrically tuned, piezo-electrically tuned, and the like. Elements of the impedance matching can be silicon devices, gallium nitride devices, silicon carbide devices, and the like. The elements can be chosen to withstand high currents, high voltages, high powers, or any combination of current, voltage, and power. The elements can be chosen to be high-Q elements.
The IMNs 108, 112 and/or control circuitry monitors impedance differences between the source 118 and the device 120 and provides control signals to tune the IMNs 108, 112 or components thereof. In some implementations, the IMNs 108, 112 can include a fixed IMN and a dynamic IMN. For example, a fixed IMN may provide impedance matching between portions of the system with static impedances or to grossly tune a circuit to a known dynamic impedance range.
In some implementations, a dynamic IMN can be further composed of a coarsely adjustable components and/or a finely adjustable components. For example, the coarsely adjustable components can permit coarse impedance adjustments within a dynamic impedance range whereas the finely adjustable components can be used to fine tune the overall impedance of the IMN(s). In another example, the coarsely adjustable components can attain impedance matching within a desirable impedance range and the finely adjustable components can achieve a more precise impedance around a target within the desirable impedance range.
It is understood that the source and/or device impedance matching networks (IMNs) can have a wide range of circuit implementations with various components having impedances to meet the needs of a particular application. U.S. Pat. No. 8,461,719 to Kesler et al. and U.S. Pat. No. 8,922,066 to Kesler et al., which are incorporated herein by reference, disclose a variety of tunable impedance networks, such as in
In embodiments, the PTU/source can include a processor module 120 to control overall operation of the source side components and a wireless communication module 122 coupled to the processor 120 to provide wireless communication to other units. It is understood that any suitable wireless communication technology can be used, such as Bluetooth®, BLE (Bluetooth® Low Energy), WiFi, radio, and the like. In embodiments, the processor module 120 can include a correlation module to correlate PTU and PRU signals, as described more fully below.
The PRU/device can include a processor module 124 to control the overall operation of the device components and a wireless communication module 126 to enable the PRU to communicate with PTU and/or PRU units.
In embodiments, the PTU includes a cross-connect detection module 128 that can detect PTU-PRU cross-connection, as described more fully below. While the cross-connect detection module 128 is shown as part of the wireless connection module 122 on the PTU, it is understood that the cross-connection module can reside in any suitable location with access to wireless communication and access to the mechanisms which control the current in the PTU transmitting coil. This may include impedance change information, voltage signals, current signals, PWM signals, and other signals transmitted by the source resonator 106, as described more fully below. For example, the cross-connect detection module 128 can form part of the PTU processor module 120.
In another scenario, the second PTU 306 is charging (in-band) the third PRU 310 while communicating with the second and third PRUs 308, 310. In this scenario, the second PTU 306 ‘believes’ that it is charging the second and third PTUs 308, 310. In general, when the in-band and out-of-band communication channels are not consistent with each other with respect to PTU and PRU, a cross-connection may be present.
In embodiments, a beacon-advertisement protocol is used to establish in-band and out-of band communication between PTUs and PRUs. A PTU can transmit beacon signals from a resonator coil that ‘look’ for nearby PRUs, e.g., a device placed on a charging pad, by detecting impedance changes due to the nearby PRU. In response, a PRU can transmit advertisement messages via wireless communication, e.g., Bluetooth®, that can include impedance change information. The PTU accepts the PRU communication request, for example, if the signal strength is above a threshold, which can be set to a level corresponding to a PRU within some given distance from the PTU. In embodiments, the PTU connects to a PRU if the PTU detects the PRU by an impedance shift and the signal strength threshold for the advertisement messages is met. In embodiments, if only one condition (impedance shift or signal strength) is met, the PTU must still issue a connection request to the PRU under certain conditions. It is understood that this arrangement may favor establishing a connection over not establishing a connection to a desired level. If a PRU has a relatively high signal strength level, a PTU may establish an out-of-band connection to the PRU, which is charged (in-band) by a different PTU or nearby PRU. In embodiments, a first PRU may be charged by a second PRU. In addition, a false impedance shift detection may result in a cross-connection situation if PRU advertisement messages are received by a PTU. Also, a connection may be required by a standard or protocol if a PRU advertisement is received a certain number of times in a given time period.
In one particular embodiment, a beacon-advertisement protocol for PTU-PRU communication is set forth in Airfuel (formerly A4WP) Wireless Power Transfer System Baseline System Specification (BSS) v1.2.1, approved May 7, 2014, which is incorporated herein by references.
It is understood that cross-connects can occur due to a wide range of parameters and protocol directives which do not limit the scope of the invention in any way.
In embodiments of the invention, PTU-PRU cross-detection can be detected by perturbing a transmit coil of a PTU and evaluating the response of the PRU coil. For example, a current level increase on the PTU transmit coil should cause a corresponding voltage increase on the receive coil of a connected PRU, and vice-versa. If the current change is not tracked by an out-of-band connected PRU, then the PRU is likely not being charged by that PTU.
In the illustrated embodiment, the coil current rises at time t0 to ITX_RISE 400 and remains there for a random amount of time tRISE1 402, which expires at time t1 at which the coil current falls to ITX_FALL 404 for a further random amount of time tFALL1 406. When this time expires, the coil current rises to ITX_RISE 400 and remains there for another random amount of time tRISE2 408. At time t3, at which time tRISE2 408 expires, the coil current level falls to ITX_FALL 404 for time tFALL2 410 which expires at time t4. The coil current can go to a desired level after cross-connect detection signaling.
In embodiments, any suitable random number generating process can be used to generate current transition times and/or time durations. In embodiments, a pseudo random number generator is used to generate the random time durations or samples of the rise and fall current levels described above. In one particular embodiment, a random number generator is seeded with a unique identifier of a hardware component in the PTU, such as an IC on a wireless communication module (see, e.g., 122
It is understood that the PTU coil current level can be the same or different after each rise and each fall. In embodiments, the coil current rise and fall times are of sufficient duration to capture at least three PRU VRECT reports. In the illustrated embodiment, an ‘X’ above or below the current level indicates illustrative PRU rectifier voltage VRECT reports to the PTU. The VRECT reports can be accepted/stored/saved after sufficient signal setting time.
If the out-of-band connected PRU is not cross-connected, the PTU coil current perturbation will cause corresponding reactions at the output of the PRU rectifier. In embodiments, the PRU sends a rectifier value VRECT to the PTU for processing to determine whether the PTU coil perturbations affected the PRU receive coil in manner expected for an in-band connected PRU. That is, if there is no cross-connection, the PRU will ‘see’ the PTU coil current perturbations and transmit rectifier values VRECT that are consistent with an in-band connected PRU.
A cross-connection module on the PTU (320,
It is understood that the parameters for detecting the presence or absence of a cross connect can be varied to meet the needs of a particular application and disconnection policy. That is, it may be very undesirable in certain applications to disconnect PRUs. In other applications, it may be desirable to disconnect PRUs that are cross-connected to the extent possible.
If the PRU is determined to be cross-connected, the PTU can disconnect 444 the PRU. In embodiments, the disconnected PRU can be placed on a so-called blacklist, for some period of time, to prevent the cross-connection from occurring again. The parameters for placement on a blacklist can be selected to meet the needs of a particular application. For example, a blacklist time can correspond to an expected number of PTUs in range of each other (capable of cross-connecting) and an amount of time to detect and address a cross-connection. It is understood that, in general, a disconnected/blacklisted PRU may readily connect with a different PTU.
In embodiments, the PRU has a unique identifier that can be used to identify the PRU for the blacklist. It is understood that any practical identifier for the PRU can be used to meet the needs of a particular application.
As shown in
Illustrative parameters, descriptions, and values are set forth in respective columns in Table 1 below. It is understood that only some of the listed variables may be used and that additional variables may be used in other cross-detection processing. It is further understood that the values listed are illustrative and can readily vary to meet the needs of a particular application as will be readily apparent to one of ordinary skill in the art.
Processing may be implemented in hardware, software, or a combination of the two. Processing may be implemented in computer programs executed on programmable computers/machines that each includes a processor, a storage medium or other article of manufacture that is readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and one or more output devices. Program code may be applied to data entered using an input device to perform processing and to generate output information.
The system can perform processing, at least in part, via a computer program product, (e.g., in a machine-readable storage device), for execution by, or to control the operation of, data processing apparatus (e.g., a programmable processor, a computer, or multiple computers). Each such program may be implemented in a high level procedural or object-oriented programming language to communicate with a computer system. However, the programs may be implemented in assembly or machine language. The language may be a compiled or an interpreted language and it may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program may be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. A computer program may be stored on a storage medium or device (e.g., CD-ROM, hard disk, or magnetic diskette) that is readable by a general or special purpose programmable computer for configuring and operating the computer when the storage medium or device is read by the computer.
Processing may also be implemented as a machine-readable storage medium, configured with a computer program, where upon execution, instructions in the computer program cause the computer to operate.
Processing may be performed by one or more programmable processors executing one or more computer programs to perform the functions of the system. All or part of the system may be implemented as, special purpose logic circuitry (e.g., an FPGA (field programmable gate array) and/or an ASIC (application-specific integrated circuit)).
Having described exemplary embodiments of the invention, it will now become apparent to one of ordinary skill in the art that other embodiments incorporating their concepts may also be used. The embodiments contained herein should not be limited to disclosed embodiments but rather should be limited only by the spirit and scope of the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.
Elements of different embodiments described herein may be combined to form other embodiments not specifically set forth above. Various elements, which are described in the context of a single embodiment, may also be provided separately or in any suitable subcombination. Other embodiments not specifically described herein are also within the scope of the following claims.
The present application claims the benefit of U.S. Provisional Patent Application No. 62/304,420, filed on Mar. 7, 2016, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62304420 | Mar 2016 | US |
