Patent Application
20130207479
1. Field of the Invention
The following description relates to electric and radio technologies, and more particularly, to a wireless power transmission system.
2. Description of the Conventional Art
A number of solutions in the field of power transmission via radio waves have been suggested, the basic ideas of which were first suggested by Nikola Tesla.
A device known as a “rectenna” may be used for transmitting wireless energy. The rectenna refers to a rectifying antenna used for performing a direct conversion of microwave energy into direct current (DC) electricity. In general, different types of antennas may be used for receiving radio frequency (RF) signals.
Most such wireless power transmission systems operate in the gigahertz (GHz) frequency range. One drawback of such solutions relates to a health hazard the applicable frequency range presents for humans.
In one general aspect, there is provided a self-resonant apparatus for a wireless power transmission system, the self-resonant apparatus including ring resonators, wherein the ring resonators may be represented by a combination having metamaterial features, the combination may include split-ring resonators (SRRs) connected in parallel to capacitors, a front surface and a rear surface of each of the SRRs may be connected to be twisted in an alternating pattern, and each SRR may be executed as a metal strip mounted on a dielectric layer and connected to a neighboring SRR by a series capacitor.
The SRRs may revolve, and an angle of the revolving may be determined for a series surface-mounted capacitor to have an optimal amount of space for mounting.
The SRRs may be provided in a round or polygonal shape.
A thickness of the dielectric layer may be in a range of 50 micrometers (μm) to 1500 μm.
A dielectric permittivity of the dielectric layer may correspond to a value in a range of 2 to 20.
At least two SRRs may be provided.
An operational frequency band of the SRRs may be in a range of 1 megahertz (MHz) to 100 MHz.
The SRRs connected in parallel to the capacitors may be manufactured by low temperature co-fired ceramics technology or printed circuit board technology.
Each of the SRRs connected in parallel to the capacitors may include an equivalent circuit including a parallel resonant LC circuit and a series capacitor.
The parallel resonant LC circuit may include an inductive element and a capacitive element, and may be connected in series to an active reactance.
The combination may be represented by an equivalent circuit including a plurality of cells, each cell may include a parallel resonant circuit formed by an SRR and a capacitor being connected in parallel, and the plurality of cells may be connected in series via the series capacitor.
A combination of the parallel resonant circuit and the series capacitor may be followed by revealing two resonant responses of typical impedance with respect to a metamaterial.
A Q-factor of the combination may correspond to a value in a range of 100 to 200.
The self-resonant apparatus may further include a magnetic rode along an axis of the SRRs.
The magnetic rode may include ferrite.
The capacitors may be embedded in an internal portion of the dielectric layer having a high dielectric permittivity.
Other features and aspects will be apparent from the following detailed description, the drawings, and the claims.
The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be suggested to those of ordinary skill in the art. The progression of processing steps and/or operations described is an example; however, the sequence of and/or operations is not limited to that set forth herein and may be changed as is to known in the art, with the exception of steps and/or operations necessarily occurring in a certain order. Also, description of well-known functions and constructions may be omitted for increased clarity and conciseness.
Referring to
The source 110 includes a variable switching mode power supply (SMPS) 111, a power amplifier 112, a matching network 113, a controller 114, and a communication unit 115.
The variable SMPS 111 may generate direct current (DC) voltage by switching alternating current (AC) voltage in a band of tens of hertz (Hz) output from a power supply. The variable SMPS 111 may output DC voltage of a predetermined level, or may adjust an output level of DC voltage based on the control of the controller 114.
A power detector 116 may detect output current and output voltage of the variable SMPS 111, and may transfer, to the controller 114, information on the detected current and the detected voltage. Additionally, the power detector 116 may detect input current and input voltage of the power amplifier 112.
The power amplifier 112 may generate power by converting DC voltage of a predetermined level to AC voltage, using a switching pulse signal in a band of a few megahertz (MHz) to tens of MHz. Accordingly, the power amplifier 112 may convert DC voltage supplied to the power amplifier 112 to AC voltage, using a reference resonant frequency FRef, and may generate communication power used for communication, or charging power used for charging. The communication power and the charging power may be used in a plurality of target devices.
The communication power may refer to low power of 0.1 milliwatt (mW) to 1 mW. The charging power may refer to high power of 1 mW to 200 W that is consumed in a device load of a target device. In various examples described herein, the term “charging” may refer to supplying power to a unit or element that is configured to charge power. Additionally, the term “charging” may refer to supplying power to a unit or element that is configured to consume power. The units or elements may include, for example, batteries, displays, sound output circuits, main processors, and various sensors.
Also, the term “reference resonant frequency” may refer to a resonant frequency that is used by the source 110. Additionally, the term “tracking frequency” may refer to a resonant frequency that is adjusted by a preset scheme.
The controller 114 may detect a reflected wave of the communication power or the charging power, and may detect mismatching that may occur between a target resonator 133 and a source resonator 131 based on the detected reflected wave. To detect the mismatching, for example, the controller 114 may detect an envelope of the reflected wave, a power amount of the reflected wave, and the like.
The matching network 113 may compensate for impedance mismatching between the source resonator 131 and the target resonator 133 to be optimal matching, under the control of the controller 114. The matching network 113 may be connected through a switch, based on a combination of a capacitor and an inductor, under the control of the controller 114.
The controller 114 may compute a voltage standing wave ratio (VSWR), based on a voltage level of the reflected wave, and based on a level of an output voltage of the source resonator 131 or the power amplifier 112. For example, when the VSWR is greater than a predetermined value, the controller 114 may determine that mismatching is detected.
In this example, the controller 114 may compute a power transmission efficiency for each of N tracking frequencies, may determine a tracking frequency FBest with the best power transmission efficiency among the N tracking frequencies, and may adjust the reference resonant frequency FRef to the tracking frequency FBest. In various examples, the N tracking frequencies may be set in advance.
The controller 114 may adjust a frequency of a switching pulse signal. Under the control of the controller 114, the frequency of the switching pulse signal may be determined For example, by controlling the power amplifier 112, the controller 114 may generate a modulation signal to be transmitted to the target 120. In other words, the communication unit 115 may transmit a variety of data 140 to the target 120 using in-band communication. The controller 114 may detect a reflected wave, and may demodulate a signal received from the target 120 through an envelope of the detected reflected wave.
The controller 114 may generate a modulation signal for in-band communication, using various ways. For example, the controller 114 may generate the modulation signal by turning on or off a switching pulse signal, by performing delta-sigma modulation, and the like. Additionally, the controller 114 may generate a pulse-width modulation (PWM) signal with a predetermined envelope.
The communication unit 115 may perform out-band communication that employs a communication channel. The communication unit 115 may include a communication module, such as one configured to process ZigBee, Bluetooth, and the like. The communication unit 115 may transmit the data 140 to the target 120 through the out-band communication.
The source resonator 131 may transfer an electromagnetic energy 130 to the target resonator 133. For example, the source resonator 131 may transfer the communication power or charging power to the target 120, using magnetic coupling with the target resonator 133.
As illustrated in
The target resonator 133 may receive the electromagnetic energy 130 from the source resonator 131. For example, the target resonator 133 may receive the communication power or charging power from the source 110, using the magnetic coupling with the source resonator 131. Additionally, the target resonator 133 may receive the data 140 from the source 110 using the in-band communication.
The matching network 121 may match an input impedance viewed from the source 110 to an output impedance viewed from a load. The matching network 121 may be configured with a combination of a capacitor and an inductor.
The rectification unit 122 may generate DC voltage by rectifying AC voltage. The AC voltage may be received from the target resonator 133.
The DC/DC converter 123 may adjust a level of the DC voltage that is output from the rectification unit 122, based on a capacity required by the load. As an example, the DC/DC converter 123 may adjust the level of the DC voltage output from the rectification unit 122 from 3 volts (V) to 10 V.
The power detector 127 may detect voltage of an input terminal 126 of the DC/DC converter 123, and current and voltage of an output terminal of the DC/DC converter 123. The detected voltage of the input terminal 126 may be used to compute a transmission efficiency of power received from the source 110. Additionally, the detected current and the detected voltage of the output terminal may be used by the controller 125 to compute an amount of power transferred to the load. The controller 114 of the source 110 may determine an amount of power that needs to be transmitted by the source 110, based on power required by the load and power transferred to the load.
When power of the output terminal computed using the communication unit 124 is transferred to the source 110, the source 110 may compute an amount of power that needs to be transmitted.
The communication unit 124 may perform in-band communication to transmit or receive data using a resonance frequency. During the in-band communication, the controller 125 may demodulate a received signal by detecting a signal between the target resonator 133 and the rectification unit 122, or detecting an output signal of the rectification unit 122. In other words, the controller 125 may demodulate a message received using the in-band communication. Additionally, the controller 125 may adjust an impedance of the target resonator 133 using the matching network 121, to modulate a signal to be transmitted to the source 110. For example, the controller 125 may increase the impedance of the target resonator 133, so that a reflected wave may be detected from the controller 114 of the source 110. Depending on whether the reflected wave is detected, the controller 114 may detect a binary number, for example “0” or “1.”
The communication unit 124 may transmit a response message to the communication unit 115 of the source 110. For example, the response message may include a “type of a corresponding target,” “information about a manufacturer of a corresponding target,” “a model name of a corresponding target,” a “battery type of a corresponding target,” a “scheme of charging a corresponding target,” an “impedance value of a load of a corresponding target,” “information on characteristics of a target resonator of a corresponding target,” “information on a frequency band used by a corresponding target,” an “amount of a power consumed by a corresponding target,” an “identifier (ID) of a corresponding target,” “information on version or standard of a corresponding target,” and the like.
The communication unit 124 may perform out-band communication using a communication channel. For example, the communication unit 124 may include a communication module, such as one configured to process ZigBee, Bluetooth, and the like. The communication unit 124 may transmit or receive the data 140 to or from the source 110 using the out-band communication.
The communication unit 124 may receive a wake-up request message from the source 110, and the power detector 127 may detect an amount of power received to the target resonator 133. The communication unit 124 may transmit, to the source 110, information on the detected amount of the power. Information on the detected amount may include, for example, an input voltage value and an input current value of the rectification unit 122, an output voltage value and an output current value of the rectification unit 122, an output voltage value and an output current value of the DC/DC converter 123, and the like.
In
The controller 125 may set a resonance bandwidth of the target resonator 133. Based on the set resonance bandwidth of the target resonator 133, a Q-factor of the target resonator 133 may be determined In this instance, the resonance bandwidth of the source resonator 131 may be wider or narrower than the resonance bandwidth of the target resonator 133.
Via a communication, the source 110 and the target 120 may share information regarding each of the resonance bandwidths of the source resonator 131 and the target resonator 133. When a power higher than a reference value is requested from the target 120, the Q-factor (Qs) of the source resonator 131 may be set to a value greater than 100. When a power lower than the reference value is requested from the target 120, the Q-factor (Qs) of the source resonator 131 may be set to a value less than 100.
In a resonance-based wireless power transmission, a resonance bandwidth may be an importance factor. When Qt indicates a Q-factor based on a change in a distance between the source resonator 131 and the target resonator 133, a change in a resonance impedance, impedance-mismatching, a reflected signal, and the like, Qt may be in inverse proportion to a resonance bandwidth, as given in Equation 1.
In Equation 1, f0 denotes a center frequency, Δf denotes a bandwidth, ΓS, D denotes a reflection loss between resonators, BWS denotes a resonance bandwidth of the source resonator 131, and BWD denotes a resonance bandwidth of the target resonator 133.
In a wireless power transmission, an efficiency U of the wireless power transmission may be given by Equation 2.
In Equation 2, κ denotes a coupling coefficient regarding energy coupling between the source resonator 131 and the target resonator 133, ΓS denotes a reflection coefficient of the source resonator 131, ΓD denotes a reflection coefficient of the target resonator 133, ω0 denotes a resonant frequency, M denotes a mutual inductance between the source resonator 131 and the target resonator 133, RS denotes an impedance of the source resonator 131, RD denotes an impedance of the target resonator 133, QS denotes a Q-factor of the source resonator 131, QD denotes a Q-factor of the target resonator 133, and Qκ denotes a Q-factor regarding energy coupling between the source resonator 131 and the target resonator 133.
Referring to Equation 2, the Q-factor may be highly associated with an efficiency of the wireless power transmission.
Accordingly, the Q-factor may be set to a great value in order to increase the efficiency of the wireless power transmission. In this instance, when QS and QD are respectively set to a significantly great value, the efficiency of the wireless power transmission may be reduced based on a change in the coupling coefficient K regarding the energy coupling, a change in a distance between the source resonator 131 and the target resonator 133, a change in a resonance impedance, impedance mismatching, and the like.
When each of the resonance bandwidths of the source resonator 131 and the target resonator 133 is set to be too narrow in order to increase the efficiency of the wireless power transmission, the impedance mismatching and the like may easily occur due to insignificant external influences. In consideration of the impedance mismatching, Equation 1 may be expressed by Equation 3.
In
In addition, the target 120 may receive wake-up power from at least one of a plurality of source devices. The target 120 may activate a communication function using the wake-up power. The target 120 may receive a configuration signal to configure a wireless power transmission network of each of the plurality of source devices. As an example, the target 120 may select the source 110 based on a receiving sensitivity of the configuration signal, and receive power from the selected source 110 wirelessly.
Referring to
Each of the plurality of cells 210 through 280 may be connected in series to a series capacitor. By way of example, all capacitors may be represented by surface-mounted elements.
The self-resonant structure may be designed as a combination of parallel resonant circuits and series capacitors. In
Referring to
The SRR 300 may include thin metallic strips 320 and 330. For example, the metallic strips 320 and 330 may include copper. The metallic strips 320 and 330 may be disposed on a dielectric layer. A thickness b of the metallic strip 320 or 330 may be less than a width a of the metallic strip 320 or 330.
For example, in
At an edge of the gap 310, the metallic strips 320 and 330 may be configured for oscillation. A thickness of the dielectric layer may be in a range of 10 micrometers (μm) to 1500 μm. A dielectric permittivity of the dielectric layer may correspond to a value in a rage of 2 to 20.
The SRR 300 may be realized in a form of a polygon having an arbitrary number of sides. The arbitrary number of sides may be determined based on technology for mounting a capacitor to be connected to the SRR 300.
Referring to
Each cell may be represented by a parallel LC circuit including a parallel capacitor C1 410 connected to an SRR. The plurality of identical cells may be connected in series by a series capacitor C0 420. The equivalent circuit of the self-resonant structure may be transformed to a series connection circuit of the plurality of identical cells being connected in series.
Referring to
The resonant frequency f1 may be a frequency corresponding to a minimum input impedance of the self-resonant apparatus, and the resonant frequency f2 may be a frequency corresponding to a maximum input impedance.
The resonance and the antiresonance in an oscillating system may be typical for a metamaterial resonant structure for providing a high quality factor of the system.
The resonant frequency may be determined by values of the capacitors C0 420 and C1 410, and by an impedance of the SRR calculated from the equivalent circuit of
Referring to
Components located on different layers may be connected by means of metalized openings, for example, holes, and transit connectors.
Dielectric layers 610 each covered with a pattern of an SRR may be disposed one over the other, and revolve, for example, turn, with respect to on another at a predetermined angle, as shown in
An angle between two adjacent SRRs for example, neighboring SRRs, may be determined in a manner to provide a sufficient amount of space for placement of the series surface mounted capacitor 640.
Each SRR of the parallel capacitor 630 and the series capacitor 640 may be described to by an equivalent electrical circuit including a parallel LC circuit connected in series to the series capacitor 640.
Each parallel circuit may include an inductance and a capacitor connected in series to an active resistance.
Referring to
A series connection between a plurality of SRRs may provide a higher inductance, and assume a higher value of load impedance. All inductors may be coupled by a mutual inductance which leads to an increase of a Q-factor of the self-resonant structure.
With regard to
Referring to
The multi-layer self-resonant structure may operate at a frequency in a range of 1 MHz to 100 MHz.
A large number of used layers may increase an input impedance of the multi-layer self-resonant structure which results in an increase of a load resistance value.
In order to obtain more uniform magnetic flux through an SRR 910, a magnetic rode, for example, a ferrite core, may be inserted along a common axis of the SRR 910.
In the multi-layer self-resonant structure, the SRR 910 may include a metallic layer 911, a dielectric layer 912, a via interconnection 913, a series surface mounted capacitor C0 914, and a parallel surface mounted capacitor C1 915.
Cells 910, 920, and 930 may be configured in an identical structure, and revolve at an accurate angle.
Referring to
The insertion of a magnetic rode 1110 into the SRR structure may entail an increase of an effective area of the SRR, and an enhancement of an effective coupling coefficient between transmitting and receiving coils of a power transmission system.
According to example embodiments, the resonant structure may be manufactured by low temperature co-fired ceramics technology or printed circuit board technology. Both technologies may allow the use of surface mounting technique. The provided structure may be implemented without a surface mounted capacitor.
A dielectric material may have a relatively high dielectric permittivity ∈r, and a required capacitance value may be achieved due to an interlayer capacitance represented by a capacitor integrated into a substrate.
According to example embodiments, the resonant structure may be used for portable wireless chargers for various electronic devices including compact devices. For example, the suggested resonant structure may be used for a charger for mobile phones. In medical fields, the suggested resonant structure may be used for cardio stimulators, pacemakers, or other electronic devices including compact devices.
According to example embodiments, the resonant structure may provide an improved resonant structure capable of producing a high inductance value at a compact size device. In addition, a mutual inductance may take place wherever among inductive components of the resonant structure, and a total inductance of the structure may show a corresponding increase.
The units described herein may be implemented using hardware components, software components, or a combination thereof. For example, a processing device may be implemented using one or more general-purpose or special purpose computers, such as, for example, a processor, a controller and an arithmetic logic unit, a digital signal processor, a microcomputer, a field programmable array, a programmable logic unit, a microprocessor or any other device capable of responding to and executing instructions in a defined manner. The processing device may run an operating system (OS) and one or more software applications that run on the OS. The processing device also may access, store, manipulate, process, and create data in response to execution of the software. For purpose of simplicity, the description of a processing device is used as singular; however, one skilled in the art will appreciated that a processing device may include multiple processing elements and multiple types of processing elements. For example, a processing device may include multiple processors or a processor and a controller. In addition, different processing configurations are possible, such as parallel processors.
The software may include a computer program, a piece of code, an instruction, or some combination thereof, for independently or collectively instructing or configuring the processing device to operate as desired. Software and data may be embodied permanently or temporarily in any type of machine, component, physical or virtual equipment, computer storage medium or device, or in a propagated signal wave capable of providing instructions or data to or being interpreted by the processing device. The software also may be distributed over network coupled computer systems so that the software is stored and executed in a distributed fashion. In particular, the software and data may be stored by one or more non-transitory computer readable recording mediums.
The non-transitory computer readable recording medium may include any data storage device that can store data which can be thereafter read by a computer system or processing device. Examples of the non-transitory computer readable recording medium include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices. Also, functional programs, codes, and code segments for accomplishing the example embodiments disclosed herein can be easily construed by programmers skilled in the art to which the embodiments pertain based on and using the flow diagrams and block diagrams of the figures and their corresponding descriptions as provided herein.
A number of examples have been described above. Nevertheless, it should be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Accordingly, other implementations are within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012100031 | Jan 2012 | RU | national |
| 10-2013-0002903 | Jan 2013 | KR | national |
