Wireless energy receiver / transmitter system and method for wireless energy transmission

Abstract

A wireless energy transmission system (100, 100a; 100b) comprising a wireless energy receiving device (120; 120') and a wireless energy transmitting device (110; 110'), wherein the wireless energy receiving device (120; 120') and / or the wireless energy transmitting device (110; 110') comprises: a first oscillator (605a) configured to output an in-phase (I) signal; a second oscillator (605b) configured to output a quadrature-phase (Q) signal having a phase difference of 90 degrees to the I signal, wherein each of the first and second oscillators comprises a resonator having at least one inductor and at least one capacitor, and a current varying block (640a, 640b) connected to the at least one inductor and configured to vary an amount of current flowing through the at least one inductor; and a monitoring device (116; 124) configured to monitor a frequency of the I and / or Q signal and to control the current variation block (640a, 640b) according to a monitoring result.

Description

background

[0001] Embodiments of the inventive concept relate to wireless energy receivers (receiving devices), wireless energy transmitters (transmitting devices), wireless energy transmission systems and methods for wireless energy transmission, which realize efficient wireless energy transmission.

[0002] Much development work has been done in the field of wireless power transmission using electromagnetic induction. Until now, electrical power can be transmitted over relatively short distances (e.g., several centimeters) using conventional methods using electromagnetic induction.

[0003] To overcome this limitation, a method using magnetic resonance has been introduced. For wireless power transmission using magnetic resonance, LC resonance can be used to tune a common resonant frequency between a transmitter / receiver pair. During this tuning process of the resonant frequency, the capacitance value is typically adjusted. However, it is not easy to fine-tune the capacitance value, making it difficult to perform accurate resonant frequency tuning.

[0004] Accordingly, a better approach to tuning the resonance frequency is desirable, which does not require direct adjustment of the inductance value “L” or the capacitance value “C”.

[0005] From the document US 2005 / 0 135 122 A1 a wireless energy transmission system is known which comprises: a wireless energy receiving device and a wireless energy transmission device, a processor which generates two rectangular signals with a 90 degree phase shift to each other, and two coils which are excited in quadrature with the aid of these signals.

[0006] From the document US 2010 / 0 289 449 A1, a device is known that comprises: a monitoring circuit configured to monitor a resonant frequency of a power source; a receiving component; and a control unit configured to change a resonant frequency of the receiving component. The device is configured to change the resonant frequency of the receiving component in response to a signal from the monitoring circuit. Summary

[0007] According to certain embodiments of the inventive concept, a wireless power transmission system is provided with a wireless power receiving device and a wireless power transmitting device. The wireless power receiving device and / or the wireless power transmitting device comprise: a first oscillator configured to output an in-phase (I) signal, a second oscillator configured to output a quadrature-phase (Q) signal with a phase difference of 90 degrees to the I signal, wherein both the first and the second oscillator comprise a resonator with at least one inductor ora coil and at least one capacitor, and a current varying block connected to the at least one inductor and configured to vary an amount of current flowing through the at least one inductor, and a monitoring device configured to monitor a frequency of the I and / or Q signal and control the current varying block according to a monitoring result.

[0008] According to certain embodiments of the inventive concept, a wireless power receiving device is provided, comprising: a first oscillator configured to output an in-phase (I) signal, and a second oscillator configured to output a quadrature-phase (Q) signal with a phase difference of 90 degrees from the I signal. Both the first and second oscillators comprise: a first coil or inductor pair having a first mutual inductance and comprising a first inductor and a second inductor, a second coil or inductor pair having a second mutual inductance and comprising a third inductor and a fourth inductor, and a capacitor connected between the first inductor and the third inductor.wherein both the first and second oscillators control a magnitude of received wireless energy by varying a resonant frequency by varying an amount of current flowing through the second and fourth inductors.

[0009] According to certain embodiments of the inventive concept, an electronic system is provided, comprising: a wireless power receiving device configured to wirelessly receive power from a wireless power transmitting device through a magnetic field and to generate received power, and a power unit configured to receive the received power from the wireless power receiving device and to supply at least a portion of internal power necessary for the operation of the electronic system. The wireless power receiving device comprises: a first oscillator configured to output an in-phase (I) signal, and a second oscillator configured to output a quadrature-phase (Q) signal with a phase difference of 90 degrees from the I signal.Both the first and second oscillators comprise a resonator comprising at least one inductor and at least one capacitor, and a current varying block connected to the at least one inductor to vary an amount of current flowing through the at least one inductor.

[0010] According to certain embodiments of the inventive concept, a method for wirelessly receiving energy using a wireless energy receiving device is provided, the method comprising: generating an in-phase (I) signal and a quadrature-phase (Q) signal having a phase difference of 90 degrees to the I signal using a quadrature oscillator having at least one pair of inductors with a mutual inductance, and adjusting a resonant frequency by changing the current flowing through one inductor of the at least one pair of inductors. Short description of the illustrations

[0011] The above and other features and advantages of the inventive concept will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which: Fig. 1 is a general block diagram of a wireless power transmission system according to embodiments of the inventive concept; Fig. 2 is a block diagram of a transmitting device and a receiving device used in accordance with certain embodiments of the inventive concept in the wireless power transmission system of Fig. 1 may be included; Fig. 3 is a block diagram of a transmitting device and a receiving device used according to further embodiments of the inventive concept in the wireless power transmission system of Fig. 1 may be included; Fig. 4 is a graph showing the frequency versus a quality factor “Q” for the wireless energy transmission system of Fig. 1 shows; Fig. 5 is a graph further illustrating resonant frequency versus energy transfer rate with respect to selected quality factors; Fig. 6 and Fig. 7A are wiring diagrams of a quadrature oscillator which, according to certain embodiments of the inventive concept, may be used in the transmitting device and / or a receiving device of Fig. 1 may be included; Fig. 7B is a block diagram of a quadrature oscillator which, according to further embodiments of the inventive concept, may be used in the transmitting device and / or a receiving device of the Fig. 6 and Fig. 7A may be included; Fig. 8, Fig. 9 and Fig. 10 wiring diagrams are showing the current change block of the Fig. 6 and Fig. 7A according to certain embodiments of the inventive concept; Fig. 11 an equivalent wiring diagram for the resonance circuit block of the Fig. 6 and Fig. 7A is; Fig. 12 and Fig. 13 three-dimensional coordinate system diagrams are which inductors for the quadrature oscillator of Fig. 7A; Fig. 14 is a diagram illustrating rectified waveforms that may be output by a quadrature oscillator according to certain embodiments of the inventive concept; Fig. 15, Fig. 16 and Fig. 17 are flowcharts summarizing methods for wireless power transfer according to certain embodiments of the inventive concept; Fig. 18 is an illustration of a wireless power transmission system according to certain embodiments of the inventive concept; Fig. 19, Fig. 20 and Fig. 21 are diagrams illustrating certain receiving devices according to embodiments of the inventive concept; Fig. 22 is a block diagram of an electronic system including a wireless power receiving device according to embodiments of the inventive concept; Fig. 23 is a block diagram of an electronic system including a wireless power receiving device according to further embodiments of the inventive concept; Fig. 24 is a block diagram of an electronic system including a wireless power receiving device according to still further embodiments of the inventive concept; and Fig. 25A and Fig. 25B are conceptual diagrams illustrating an automotive application for a wireless power receiving device according to certain embodiments of the inventive concept. Detailed description of the embodiments

[0012] The inventive concept will now be described in some detail with reference to the accompanying drawings. However, the invention may be embodied in many different forms and should not be construed as limited to the illustrated embodiments. Rather, these embodiments are provided so that this disclosure will be concise and complete, and will fully convey the scope of the invention to those skilled in the art. Throughout the description and drawings, like reference numerals and designations refer to the same or similar elements.

[0013] It will be appreciated that when an element is referred to as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intervening elements. In contrast, when an element is referred to as "directly connected" or "directly coupled" to another element, there are no intervening elements. As used herein, the term "and / or" includes all combinations of one or more of the listed items in association and may be abbreviated as " / ".

[0014] It will be appreciated that although the terms first, second, etc. may be used herein to describe various elements, these elements are not intended to be limited by these terms. These terms are used merely to distinguish one element from another. For example, a first signal could be referred to as a second signal, and similarly, a second signal could be referred to as a first signal, without departing from the teachings of the disclosure.

[0015] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a" and "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is further understood that the terms "comprises" and / or "having" or "includes" and / or "including" indicate the presence of stated features, ranges, integers, steps, acts, elements, and / or components when used in this specification, but do not preclude the presence or addition of one or more other features, ranges, integers, steps, acts, elements, components, and / or groups thereof.

[0016] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It is further understood that terms used in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant art and / or the present application and should not be interpreted in an idealized or overly formal manner, unless expressly defined herein.

[0017] Figure 1 is a general block diagram of a wireless power transmission system 100 according to certain embodiments of the inventive concept. The wireless power transmission system 100 includes a transmitting device 110 and a receiving device 120. The transmitting device 110 and the receiving device 120 are separated by a distance "D" (e.g., several centimeters).

[0018] The transmitting device 110 can transmit energy to the receiving device 120 via a wireless connection, wherein the transmitting device 110 and the receiving device 120 include a resonator (not shown). The resonator can be an inductance "L" / capacitance "C" (or LC) resonator, but the inventive concept is not limited thereto.

[0019] The transmitting device 110 is connected to a power source 130 to receive a first power voltage VS1. Energy is wirelessly transmitted from the transmitting device 110 to the receiving device 120 by means of an induced magnetic field. That is, a transfer of magnetic energy can be performed between an inductor included in the transmitting device 110 and an inductor included in the receiving device 120.

[0020] The receiving device 120 is connected to a power consumption device 140. The power consumption device 140 consumes power derived from the energy transmitted via the wireless connection. For example, the receiving device 120 can convert the wirelessly received energy into a received power VR and provide the received power VR to the power consumption device 140. The power consumption device 140 can use the received power VR supplied by the receiving device 120 and / or a separate supply power voltage VS2.

[0021] The wireless power transmission system 100 generally includes two devices, that is, the transmitting device 110 and the receiving device 120, but embodiments of the inventive concept are not limited thereto. The wireless power transmission system 100 may also include three or more devices. In addition, the receiving device 120 and the power consumption device 140 are Fig. 1 as separate elements, but these can be implemented in a single element.

[0022] Fig. 2 is a block diagram showing the transmitting device 110 and receiving device 120 of the wireless power transmission system 100a shown in Fig. 1 is shown, further represents. With reference to Fig. 2, the transmitting device 110 includes a fixed-frequency oscillator 112. The receiving device 120 includes a variable-frequency oscillator 121, a frequency adjuster 122, and a frequency monitor 124.

[0023] The fixed frequency oscillator 112 outputs a signal having a fixed frequency. The fixed frequency oscillator 112 and the variable frequency oscillator 121 may include a quadrature oscillator (not shown). The fixed frequency oscillator 112 may output an in-phase (I) signal having a positive signal and a negative signal, and a quadrature phase (Q) signal having a quadrature phase signal of the positive signal and a quadrature phase signal of the negative signal. The variable frequency oscillator 121 receives the I and Q signals from the fixed frequency oscillator 112 via a wireless connection. This will be described with reference to the Fig. 6 and Fig. 7A is described in detail.

[0024] The frequency monitor 124 monitors the frequency of the variable frequency oscillator 121 and outputs a control signal CON which controls the frequency adjuster 122.

[0025] The frequency adjuster 122 adjusts the frequency of the receiving device 120 based on the control signal CON such that the frequency of the receiving device 120 is equal to that of the transmitting device 110. In other words, the frequency adjuster 122 changes the frequency of the variable-frequency oscillator 121 in response to the control signal CON of the frequency monitoring device 124.

[0026] In further embodiments of the inventive concept, different approaches, such as using a power monitor (not shown) or a Hall sensor (not shown), may be used instead of the frequency monitor 124. The power monitor may monitor the strength of the wireless energy that the receiving device 120 receives from the transmitting device 110 and output the control signal CON to increase the amount of wireless energy. The strength of the wireless energy may be monitored by measuring the strength of the I and Q signals. Alternatively, a Hall sensor may detect the strength of a magnetic field and output the control signal CON to increase the strength of the magnetic field. This approach will be described with reference to Fig. 6 to 9 are described in more detail.

[0027] Fig. 3 is a schematic block diagram of a transmitting device 110' and a receiving device 120' used in the Fig. 1, according to further embodiments of the inventive concept. With reference to Fig. 3, the transmitting device 110' includes a variable frequency oscillator 112', a frequency adjuster 114, and a frequency monitoring device 116. The receiving device 120' includes a fixed frequency oscillator 121'.

[0028] The variable frequency oscillator 112' generates a signal having a frequency that can be varied by the frequency adjuster 114. The variable frequency oscillator 112' and the fixed frequency oscillator 121' may include a quadrature oscillator (not shown). The variable frequency oscillator 112' outputs an I signal containing a positive signal and a negative signal, and a Q signal containing a quadrature-phase output of the positive signal and a quadrature-phase output of the negative signal. The fixed frequency oscillator 121' receives the I and Q signals from the variable frequency oscillator 112' via a wireless connection. This approach will be described with reference to the Fig. 6 and Fig. 7A described in more detail.

[0029] The frequency monitor 116 monitors the frequency of the variable frequency oscillator 112' and outputs a control signal CON for controlling the frequency adjuster 114.

[0030] The frequency adjuster 114 adjusts the frequency of the transmitting device 110' based on the control signal CON such that the frequency of the transmitting device 110' is equal to that of the receiving device 120'. This is described with reference to the Fig. 6 to 9 are described in detail later.

[0031] Fig. 4 is a diagram showing the relationships between frequency and a quality factor “Q” in the wireless power transmission system 100 of Fig. 1. In Fig. 4 gives a curve Q 1 the quality factor of the transmission device 110 and a curve Q 2 indicates the quality factor of the receiving device 120. If the receiving device 120 has a frequency of W 2the energy transmission efficiency increases according to the quality factor Q 1 of the transmission device 110. In particular, the higher the quality factor required by the wireless power transmission system 100, the greater the change in power transmission efficiency as a function of frequency.

[0032] The transmission device 110 has a maximum quality factor at the frequency W 1 and thereby the efficiency of energy transmission to the receiving device 120 at the frequency W 1 maximum.

[0033] Accordingly, the energy transfer efficiency can be improved by adjusting the resonance frequency between the transmitting device 110 and the receiving device 120 by adjusting the frequency of the receiving device 120 from W 2 to W 1 be increased.

[0034] Fig. Figure 5 is a graph showing the resonance frequency versus an energy transfer rate of V R / V T as a function of the quality factor. With reference to Fig. 5, the quality factor decreases in the order of a first graphical representation 410, a second graphical representation 420 and a third graphical representation 430.

[0035] With reference to the first graph or curve 410 with the highest quality factor, the energy transfer rate V R / V T rapidly if the resonance frequency changes only slightly.

[0036] Accordingly, if the wireless energy transmission system 100 of Fig. 1 requires a high quality factor, matching the resonance frequency between the transmitting device 110 and the receiving device 120 may be very important.

[0037] The Fig. 6 and Fig. 7A are wiring diagrams illustrating a quadrature oscillator 600 included in the transmitting device 110 and / or the receiving device 120 of the wireless transmission system 100 of Fig. 1. In other words, the Fig. 6 and Fig. The quadrature oscillator 600 shown in Figure 7A can be used in the embodiments with the variable frequency oscillator 121 and the frequency adjuster 122 shown in Fig. 2, and can also be used in the embodiments with the variable frequency oscillator 121' and the frequency adjuster 114 shown in Fig. 3. The following describes a case using the quadrature oscillator 600 in the embodiments with the variable frequency oscillator 121 and the frequency adjuster 122 shown in Fig. 2. The Fig. The quadrature oscillator 600 shown in Figure 6 is the same as that shown in Fig. 7A is shown.

[0038] With reference to the Fig. 6 and Fig. 7A, the quadrature oscillator 600 includes a first oscillator 605a and a second oscillator 605b.

[0039] The first oscillator 605a may output an I signal and the second oscillator 605b may output a Q signal having a phase difference of 90 degrees from the I signal.

[0040] The first oscillator 605a includes a resonant circuit block 610a, a negative resistance block 615a, a coupling circuit block 620a, a bias block 630a, and a current varying block 640a. The second oscillator 605b includes a resonant circuit block 610b, a negative resistance block 615b, a coupling circuit block 620b, a bias block 630b, and a current varying block 640b.

[0041] The resonance circuit block 610a contains inductors or coils L 1 and L 2 and capacitors C 1 and C 2 and determines the frequency of the I signals I p and I n . Between the inductors L 1 and L 2 Mutual inductances occur and a mutual inductance value is M.

[0042] The resonance circuit block 610b contains inductors or coils L 3 and L 4 and capacitors C 3 and C 4 and determines the frequency of the Q signals Q p and Q n . Between the inductors L 1 and L 2 Mutual inductances occur and a mutual inductance value is M.

[0043] Each of the inductors L 1 , L 2 , L 3 and L 4may be implemented as an on-chip inductor, but the inventive concept is not limited thereto. The on-chip inductor may be implemented with conductor (e.g., metal) wiring on a semiconductor chip.

[0044] The resonant circuit block 610a has an associated positive resistance of the inductors L 1 and L 2 and the capacitors C 1 and C 2 , if not optimal, and thus the output of the resonant circuit block 610a may exhibit the response characteristics of an RLC circuit. Consequently, a damping oscillation may occur.

[0045] The resonant circuit block 610b also has an associated positive resistance of the inductors L 3 and L 4 and the capacitors C 3 and C 4, if not optimal, and thus the output of the resonant circuit block 610b may exhibit the response characteristics of an RLC circuit. Consequently, a damping oscillation may occur.

[0046] Accordingly, the negative resistance blocks 615a and 615b are connected to the resonant circuit blocks 610a and 610b, respectively, to generate a negative resistance that balances the positive resistance of the resonant circuit blocks 610a and 610b.

[0047] The negative resistance block 615a contains cross-coupled N-type metal oxide semiconductor (NMOS) transistors T 1 and T 2 . The NMOS transistors T 1 and T 2 are cross-coupled so that the negative I signal I n by connecting the NMOS transistor T 2 is output and fed to a gate of the NMOS transistor T 1 is input, and so that the positive I signal I pby connecting the NMOS transistor T 1 is output and fed to a gate of the NMOS transistor T 2 is entered.

[0048] The negative resistance block 615b contains cross-coupled NMOS transistors T 3 and T 4 . The NMOS transistors T 3 and T 4 are cross-coupled so that the negative Q signal Q n by connecting the NMOS transistor T 4 is output and fed to a gate of the NMOS transistor T 3 is input, and so that the positive Q signal Q p by connecting the NMOS transistor T 3 is output and fed to a gate of the NMOS transistor T 4 is entered.

[0049] The coupling circuit block 620a contains two NMOS transistors T 5 and T 6 . The coupling circuit block 620b contains two NMOS transistors T 7 and T 8. The coupling circuit blocks 620a and 620b can couple or connect the first and second oscillators 605a and 605b, respectively.

[0050] The positive Q signal Q p becomes a gate of the NMOS transistor T 5 entered and the negative Q signal Q n becomes a gate of the NMOS transistor T 6 entered.

[0051] The negative I signal I n becomes a gate of the NMOS transistor T 7 entered and the positive I signal I p becomes a gate of the NMOS transistor T 8 entered.

[0052] The bias blocks 630a and 630b are connected to the negative resistance blocks 615a and 615b, respectively, and contain NMOS transistors T 9 or T 10 .

[0053] The NMOS transistors T 9 and T 10 the bias currents I b1 or I b2 based on bias voltages V b1 or V b2which are entered to their gates.

[0054] The current changing block 640a may change the current flowing in the resonant circuit block 610a based on an input control signal CON_1 received from the frequency monitor 124.

[0055] The current changing block 640b may change the current flowing in the resonant circuit block 610b based on an input control signal CON_2 received from the frequency monitor 124.

[0056] For example, the currents I c1 and I c2 based on the input control signals CON_1 and CON_2, respectively. Currents flowing in the resonant circuit blocks 610a and 610b, and in particular currents flowing in the inductors L 2 and L 4stream can be changed by coupling circuit blocks 620a and 620b. The input control signals CON_1 and CON_2 can be digital signals of at least two bits. The input control signals CON_1 and CON_2 can be the same or different from each other. The input control signals CON_1 and CON_2 can be symmetrical (e.g., complementary) to each other.

[0057] The current change blocks 640a and 640b are generated with reference to the Fig. 8, Fig. 9 and Fig. 10 described in more detail.

[0058] As a result, the frequency of a signal generated by the first and second oscillators 605a and 605b is changed without directly changing the inductance of the inductors L 1 to L 4 and the capacitance of the capacitors C 1 to C 4 This will be discussed later with reference to Fig. 11 described in detail.

[0059] Fig. 7B is a block diagram of the receiving device 120 of Fig. 1 according to certain embodiments of the inventive concept. With reference to the Fig. 6 to 7B, the receiving device 120 further includes a bias voltage generator 650 and a rectifier 660 in the quadrature oscillator 600, which is Fig. 6 and Fig. 7A. It will be apparent to those skilled in the art that the receiving device 120 includes the frequency monitoring device 124 of Fig. 2 or the frequency monitoring device 116 of Fig. 3 may contain.

[0060] The bias voltage generator 650 generates the bias voltages V b1 and V b2 which are connected to the gates of the respective NMOS transistors T 9 and T 10 be entered.

[0061] The rectifier 660 converts the I signal I p and I nwhich are output from the resonance circuit block 610a, and the Q signals Q p and Q n , which are output from the resonant circuit block 610b, into the reception power VR. The rectifier 660 can, for example, generate an alternating current (AC) power based on the I signals I p and I n and the Q signals Q p and Q n rectify, thereby generating direct current (DC) power, i.e. the received power VR.

[0062] Fig. 7B is a block diagram of a receiving device consistent with embodiments of the inventive concept, however, a transmitting device may be configured in a similar manner.

[0063] The Fig. 8, Fig. 9 and Fig. 10 are wiring diagrams of the current change blocks 640a and 640b of the Fig. 6 and Fig. 7 according to certain embodiments of the inventive concept. To avoid redundancy, only the current modification block 640a will be described, since the structure and operation of the current modification block 640a may be similar to those of the current modification block 640b.

[0064] In the Fig. 8, the current variation block 640a includes at least two NMOS transistors, but may be configured in various ways (for example, with four NMOS transistors T A , T B , Tc and T D ).

[0065] With reference to Fig. 8, the input control signal CON_1 is applied to the gates of the respective NMOS transistors T A , T B , Tc and T D applied or applied. The NMOS transistors T A , T B , Tc and T Dare selectively switched in response to the input control signal CON_1. The input control signal CON_1 can be a 4-bit digital signal. If the 4-bit digital signal is equal to "1100", the two NMOS transistors T A and T B from the four NMOS transistors T A , T B , Tc and T D switched ON and the other two NMOS transistors Tc and T D are switched OFF.

[0066] The four NMOS transistors T A , T B , Tc and T D can have different width-to-length ratios, so that current flowing into each of the NMOS transistors T A , T B , Tc and T D can be changed. Consequently, the current I c1 be changed.

[0067] A node N0 in Fig. 8 corresponds to a node N_1 or N_2 in the Fig. 6 and Fig. 7A.

[0068] The current change block 640a may be formed as a circuit with a current mirror and is configured such that it has four NMOS transistors TR 1 , TR 2 , TR 3 and TR 4 and a power source I A at the Fig. 9 contains the embodiments shown.

[0069] With reference to Fig. 9, the input control signal CON_1 is applied to switches SW1 and SW2, which control an opening and closing switching operation (e.g., 0 and 1) in the current mirror.

[0070] The opening / closing of the switches SW1 and SW2 is controlled using the input control signal CON_1 such that the current I c1 is changed. The input control signal CON_1 can be a 2-bit digital signal. When the input control signal CON_1 is equal to "10," switch SW1 is closed, while switch SW2 is open.

[0071] In a case where the first and second switches SW1 and SW2 are open, a current I A , which is integrated into the NMOS transistor TR 1 flows into the NMOS transistor TR 2 and into the NMOS transistors TR 3 and TR 4 no current flows. Accordingly, the current I c1 equal to the current I A .

[0072] In a case where only the first switch SW1 is closed, the current I A into the NMOS transistor TR 3 and the NMOS transistor TR 2 . Consequently, the current 1 c1 to 2I A .

[0073] In a case where both the first and second switches SW1 and SW2 are closed, the current I A into the NMOS transistors TR 3 and TR 4 and the NMOS transistor TR 2 . Consequently, the current I c1 to 3I A .

[0074] It is obvious that the magnitude of the current 1 c1 is also adjusted differently when the size of the NMOS transistors TR 1 , TR 2 , TR 3 and TR 4 is changed.

[0075] A node N1 in Fig. 9 corresponds to node N_1 or N_2 in the Fig. 6 and Fig. 7A.

[0076] The current change block 640a may be formed as a circuit with a current mirror and is configured such that it has two NMOS transistors TR 5 and TR 6 and three power sources I B , Ic and I D at the Fig. 10 illustrated embodiments.

[0077] With reference to Fig. 10, the input control signal CON_1 is applied to switches SW3, SW4 and SW5, which provide an opening and closing switching operation (e.g. 0 and 1) at the current sources I B , Ic and I Dsteer.

[0078] The opening / closing of the switches SW3, SW4 and SW5 is controlled using the input control signal CON_1 such that the current I c1 is changed. The input control signal CON_1 can be a 3-bit digital signal. When the input control signal CON_1 is equal to "110", switches SW3 and SW4 are closed, while switch SW5 is open.

[0079] In a case where the third switch SW3 is closed and the fourth and fifth switches SW4 and SW5 are open, a current I B , which is integrated into the NMOS transistor TR 5 flows into the NMOS transistor TR 6 . Accordingly, the current I c1 equal to the current I B .

[0080] In a case where the third and fourth switches SW3 and SW4 are closed and the fifth switch SW5 is open, a current I B +I C into the NMOS transistor TR6 . Consequently, the current I c1 to I B +I C .

[0081] In a case where all of the third to fifth switches SW3, SW4 and SW5 are closed, a current I B +I C +I D into the NMOS transistor TR 6 . Consequently, the current I c1 to I B +I C +I D .

[0082] It can be seen that the magnitude of the current I c1 is also adjusted differently when the size of the NMOS transistors TR 5 and TR 6 is changed.

[0083] A node N2 in Fig. 10 corresponds to the node N_1 or N_2 in the Fig. 6 and Fig. 7A.

[0084] Fig. 11 is an equivalent wiring diagram for the resonant circuit block 610a or 610b of the Fig. 6 and Fig. 7. An approach for adjusting the resonant frequency in the resonant circuit blocks 610a and 610b is described with reference to Fig. 11 described.

[0085] If the frequency of the Fig. 11 is denoted by “w”, the following relationship exists: VE=jwL1iL1+jwMiL2=iL1 / (jwCE)

[0086] In the quadrature oscillator 600, which is used in the Fig. 6 and Fig. 7A, the current i L1 , which in the inductor L 1 flows, and the current i L2 , which in the inductor L 2 flowing, a 0- or 180-degree phase difference to each other. Accordingly, i L2 =α iL1 , where α is a real number. Equation 1 can be rewritten as Equation 2: VE=jw(L1+αM)iL1

[0087] As a result, the value of α can be changed by changing the current i L2, which flows in the inductor L2, can be changed, so that an induction value from the point of view of a capacitor C E can be changed.

[0088] In general, a resonance frequency w 0 with respect to a capacitor C and an inductor L is defined as 1LC and thereby the resonance frequency of the resonance circuit blocks 610a and 610b can be changed.

[0089] With reference to Fig. 11 is when the current i L2 , which in the inductor L 2 flows, is changed by the current changing blocks 640a and 640b, an inductance value from the perspective of the capacitor C E by L 1 to L 1 +αM. Accordingly, the resonance frequency of the resonance circuit blocks 610a and 610b can be changed.

[0090] The Fig. 12 and Fig. 13 are three-dimensional coordinate system diagrams showing inductors of the quadrature phase oscillator 600 of Fig. 7A according to certain embodiments of the inventive concept. Fig. 12 shows the inductors L 1 and L 2 of the first oscillator 605a in the quadrature oscillator 600. Fig. 13 shows the inductors L 3 and L 4 of the second oscillator 605b in the quadrature oscillator 600.

[0091] The Fig. 12 and Fig. 13 show that the inductors L 1 and L 2 perpendicular to the inductors L 3 and L 4 However, the inventive concept is not limited to the present embodiments. For example, the inductors L 1 and L 2 parallel to the inductors L 3 and L 4or can be arranged at a certain angle (for example 0 to 180 degrees) to the inductors L 3 and L 4 be arranged.

[0092] When the transmission device 110 receives the Fig. 12 and Fig. 13, even if an inductor (not shown) included in the receiving device 120 is perpendicular to the inductors L 1 and L 2 of the first oscillator 605a, a Q signal which is orthogonal to an I signal output from the first oscillator 605a can be generated using the inductors L 3 and L 4 of the second oscillator 605b so that energy can be transmitted to the receiving device 120.

[0093] In other words, if in the transmission device 110 the inductors L 1 and L 2of the first oscillator 605a in a perpendicular relationship to the inductors L 3 and L 4 of the second oscillator 605b, the receiving device 120 can stably receive wireless energy without being affected by the positions of the inductors L included in the receiving device 120 1 , L 2 , L 3 and L 4 to be strongly bound.

[0094] The transmission device 110 can be installed in a specific area (hereinafter referred to as a "charging zone") so that the receiving device 120 can wirelessly receive energy. The charging zone can be inside or outside a building or a vehicle. The transmission device 110 can be installed in the charging zone such that the inductors L 1 and L 2 of the first oscillator 605a at right angles to the inductors L 3 and L 4 of the second oscillator 605b.

[0095] Fig. Figure 14 is a diagram of rectified waveforms output by a quadrature oscillator according to certain embodiments of the inventive concept. The quadrature oscillator 600 shown in Fig. 7A, gives rectified outputs V 1 and V Q with the Fig. 14 waveforms shown over time.

[0096] If only one of the waveforms of the rectified outputs V 1 and V Q used to transmit energy to the receiving device 120 may, due to the discontinuity at zero voltage points t A , t B , t C , t D and t E a problem may occur.

[0097] However, when both the transmitting device 110 and the receiving device 120 include the quadrature oscillator 600 according to embodiments of the inventive concept, one of the rectified outputs V 1 and V Q with a peak at the zero voltage points t A and t B or tc, t D and t E of the other of the rectified outputs V 1 and V Q . Consequently, energy transfer can be carried out more effectively.

[0098] The Fig. 15, Fig. 16 and Fig. 17 are flowcharts summarizing methods for wireless power transmission according to embodiments of the inventive concept. The method for wireless power transmission may be implemented by the wireless power transmission system 100 of Fig. 1 should be carried out.

[0099] Fig. 15 is a general flowchart for the wireless power transfer method performed by the wireless power transfer system 100. Fig. 16 is a flowchart specifically describing the frequency adjustment performed by the transmitting device 110 or the receiving device 120 of the wireless power transmission system 100, and Fig. Figure 17 is a flowchart describing in particular the frequency adjustment.

[0100] With reference to Fig. 15, power is supplied by a power source to a wireless power transmission device (S110).

[0101] Based on the supplied power, power is transmitted from the wireless power transmitting device to a wireless power receiving device through a magnetic field between the wireless power transmitting device and the wireless power receiving device (S120). To efficiently transmit power to the wireless power receiving device, frequency tuning is performed between the wireless power transmitting device and the wireless power receiving device.

[0102] For frequency tuning, a frequency of the wireless power receiving device can be adjusted. At least two signals with a phase difference of 90 degrees can be transmitted to the wireless power receiving device. The amount of current flowing into an inductor within the wireless power receiving device can be varied such that frequency tuning between the wireless power transmitting device and the wireless power receiving device can be achieved. As described above, in other embodiments, a frequency of the wireless power transmitting device can be adjusted.

[0103] The power transmitted to the wireless power receiving device is supplied to an electronic power consumption device connected to the wireless power receiving device (S130).

[0104] With reference to Fig. 16, a signal generator generates at least two signals (for example, an I signal and a Q signal) with a phase difference of 90 degrees (S210).

[0105] A frequency monitor monitors a frequency of the at least two signals (S220). A frequency adjuster adjusts the frequency of the wireless power receiving device based on a monitoring result (S230), so that frequency matching between the wireless power transmitting device and the wireless power receiving device is achieved. That is, the frequency can be adjusted by changing the amount of current flowing into an inductor within the wireless power receiving device.

[0106] With reference to Fig. 17, for frequency tuning between the wireless power transmitting device and the wireless power receiving device, the amount of current flowing into an inductor within the wireless power receiving device is changed (S310).

[0107] Accordingly, a resonant frequency is tuned between the wireless power transmitting device and the wireless power receiving device (S320). Once the frequency tuning is achieved or completed, energy can be effectively transmitted to the wireless power receiving device.

[0108] As described above, in the method for wireless energy transmission according to the embodiments described in the Fig. 15, Fig. 16 and Fig. 17, the resonance frequency can be adjusted without directly adjusting an induction value or a capacitance value, thereby realizing effective wireless power transmission.

[0109] Fig. 18 is an illustration of a wireless energy transmission system 1700 according to certain embodiments of the inventive concept. Referring to Fig. 18, the wireless energy transmission system 1700 includes a transmitting device 1750 and a receiving device 1755. The transmitting device 1750 may be implemented in the form of a pad for transmitting energy, and the receiving device 1755 may be a mobile device, for example, a mobile phone.

[0110] Although not shown, the transmitting device 1750 may be installed at a specific place or position, for example, a wall, a table, or a pocket, at a predetermined distance from the receiving device 1755 to wirelessly transmit power to the receiving device 1755. The receiving device 1755 may receive power from the transmitting device 1750 even if it is not in communication with the receiving device 1755 or is located a short distance from it.

[0111] The transmission device 1750 includes a first oscillator 1751 and a second oscillator 1752, which forms a quadrature oscillator, and is powered externally through a connector 1760.

[0112] The receiving device 1755 includes a portable telephone body 1730 and a portable telephone casing 1740. The portable telephone body 1730 includes a battery 1710 and a charger 1720. The portable telephone casing 1740 includes a first oscillator 1741 and a second oscillator 1742 forming a quadrature oscillator.

[0113] When power is supplied to the transmitting device 1750, energy is transferred to the first and second oscillators 1741 and 1742 of the receiving device 1755 through the first and second oscillators 1751 and 1752 of the transmitting device 1750.

[0114] When the energy is transmitted to the receiving device 1755, the receiving device 1755 can charge the battery 1710 with the energy through the charger 1720.

[0115] Although the first and second oscillators 1741 and 1742 of the receiving device 1755 are Fig. 18 are positioned within the portable phone case 1740, the scope of the inventive concept is not limited to these embodiments. For example, the first and second oscillators 1741 and 1742 may be positioned within the portable phone body 1730.

[0116] The Fig. 19, Fig. 20 and Fig. 21 are illustrations of the receiving device 120 according to various embodiments of the inventive concept. In contrast to the Fig. 18, the transmission device 110 in the embodiments shown in the Fig. 19 to 21 are omitted.

[0117] With reference to Fig. 19, the receiving device 120 can be implemented in the form of three-dimensional (3D) glasses 1900. The 3D glasses 1900 can contain, in the frame of two lenses, a first oscillator 1910 and a second oscillator 1920, respectively, which form a quadrature oscillator.

[0118] Accordingly, when power is supplied to the transmission device 110, energy can be supplied via a wireless connection to the 3D glasses 1900 positioned at a predetermined distance from the transmission device 110.

[0119] With reference to Fig. 20, the receiving device 120 can be implemented in the form of a headset 2000, for example, a Bluetooth headset. A first oscillator 2010 and a second oscillator 2020, which form a quadrature oscillator, can, as in Fig. 20, may be included in the headset 2000.

[0120] Accordingly, when power is supplied to the transmission device 110, energy can be delivered via a wireless connection to the headset 2000, which is positioned at a predetermined distance from the transmission device 110.

[0121] With reference to Fig. 21, the receiving device 120 may be implemented in the form of a surround sound speaker system 2100. A first oscillator 2110 and a second oscillator 2120, which form a quadrature oscillator, may, as in Fig. 21, may be included in the surround sound speaker system 2100.

[0122] Accordingly, when power is supplied to the transmitting device 110, power can be supplied to the surround sound speaker system 2100, which is positioned within a predetermined distance from the transmitting device 110, via a wireless connection. The receiving device 120 is implemented in both speakers of the surround sound speaker system 2100. Alternatively, the transmitting device 110 and the receiving device 120, respectively, can be implemented in the two speakers of the surround sound speaker system 2100. As a further alternative, the transmitting device 110 can be implemented in the surround sound speaker system 2100 and can wirelessly transmit power to the receiving device 120, which is positioned nearby.

[0123] Fig. 22 is an illustration of an electronic system 700 including the wireless energy receiving device 120 according to certain embodiments of the inventive concept. Referring to Fig. 22, the electronic system 700 includes the wireless energy receiving device 120, a system-on-chip (SoC) 710, an antenna 701, a radio frequency (RF) transceiver 703, an input device 705, a display 707, and a power unit 709.

[0124] The wireless power receiving device 120, which is a wireless power receiving device according to certain embodiments of the inventive concept, wirelessly receives power from a wireless power transmitting device and generates a received power VR and supplies it to the power unit 709. The power unit 709 provides internal power for the operations of the internal elements 703, 705, 707, and 710 of the electronic system 700.

[0125] The RF transceiver 703 transmits and receives RF signals through the antenna 701. The RF transceiver 703 can convert an RF signal received by the antenna 701 into a signal that can be processed by the SoC 710.

[0126] The SoC 710 processes the signal output from the RF transceiver 703 and transmits a processed signal to the display 707. The RF transceiver 703 may also convert a signal output from the SoC 710 into an RF signal and output the RF signal through the antenna 701. The SoC 710 may include a central processing unit (CPU) (not shown) that controls the overall operation of the electronic system 700.

[0127] The input device 705 enables control signals for controlling the operation of the SoC 710 or data to be processed by the SoC 710 to be input into the electronic system 700. The input device 705 may be implemented by a pointing device, such as a touch pad or a computer mouse, a keypad, or a keyboard.

[0128] Fig. 23 is an illustration of an electronic system 800 including the wireless energy receiving device 120 according to further embodiments of the inventive concept. Referring to Fig. 23, the electronic system 800 may be implemented as a personal computer (PC), a network server, a tablet PC, a netbook, an e-reader, a personalized digital assistant (PDA), a portable multimedia player (PMP), an MP3 player, or an MP4 player.

[0129] The electronic system 800 includes the wireless energy receiving device 120, a power unit 805, an SoC 810, a storage device 801, a memory controller 802 that controls the data processing operations of the storage device 801, a display 803, and an input device 804.

[0130] The wireless power receiving device 120, which is a wireless power receiving device according to certain embodiments of the inventive concept, wirelessly receives power from a wireless power transmitting device and generates a received power VR and supplies it to the power unit 805. The power unit 805 provides internal power for the operations of the internal elements 801, 802, 803, 804, and 810 of the electronic system 800.

[0131] The SoC 810 may display data stored in the memory device 801 through the display 803 according to data input through the input device 804. The input device 804 may be implemented by a pointing device, such as a touch pad or a computer mouse, a keypad, or a keyboard. The SoC 810 may control the overall operation of the electronic system 800 and the operations of the memory controller 802. For this control, the SoC 810 may include a CPU (not shown).

[0132] The memory controller 802, which controls the operations of the memory device 801, may be implemented as a part of the SoC 810 or as a chip separate from the SoC 810.

[0133] Fig. 24 is an illustration of an electronic system 900 including the wireless energy receiving device 120 according to further embodiments of the inventive concept. Referring to Fig. 24, the electronic system 900 may be implemented as an image processing device, such as a digital camera or a mobile phone equipped with a digital camera, a PDA, a PMP, or a smartphone.

[0134] The electronic system 900 includes the wireless energy receiving device 120, a power unit 905, an SoC 910, a storage device 901, and a memory controller 902 that controls the data processing operations of the storage device 901. The electronic system 900 may also include an image sensor 903 and a display 904.

[0135] The wireless power receiving device 120, which is a wireless power receiving device according to certain embodiments of the inventive concept, wirelessly receives power from a wireless power transmitting device and generates a received power VR and supplies it to the power unit 905. The power unit 905 provides internal power for the operations of the internal elements 901, 902, 903, 904, and 910 of the electronic system 900.

[0136] The image sensor 903 converts optical images into digital signals and outputs the digital signals to the SoC 910 or the memory controller 902. According to the control of the SoC 910, the digital signals can be displayed by the display 904 and stored in the memory device 901 by the memory controller 902.

[0137] Data stored in the storage device 901 may be displayed by the display 904 under the control of the SoC 910 or the memory controller 902. The memory controller 902, which controls the operations of the storage device 901, may be implemented as part of the SoC 910 or as a separate chip from the SoC 910. The SoC 910 may include a CPU (not shown) that controls the overall operation of the electronic system 900.

[0138] The Fig. 25A and Fig. 25B are illustrations of a vehicle 1100 with the wireless power receiving device 120 according to certain embodiments of the inventive concept. Referring to the Fig. 25A and Fig. 25B, the vehicle 1100 includes a wireless charging unit 1110. The wireless charging unit 1110 may include the wireless power receiving device 120 and a rechargeable battery 1112.

[0139] The wireless power receiving device 120, which is a wireless power receiving device according to certain embodiments of the inventive concept, wirelessly receives power from a wireless power transmitting device and generates a received power VR and supplies it to the rechargeable battery 1112.

[0140] For example, the rechargeable battery 1112 may be charged using a wireless power transfer method according to certain embodiments of the inventive concept while the vehicle 1100 is parked in a parking lot.

[0141] As described above, in a wireless power receiving device, a wireless power transmitting device, a wireless power transmitting system including both devices, and a wireless power transmitting method according to some embodiments of the inventive concept, a resonance frequency is adjusted without directly adjusting an inductance value or a capacitance value, thereby realizing efficient wireless power transmission.

Claims

[1] Wireless energy transmission system (100, 100a; 100b) with a wireless energy receiving device (120; 120') and a wireless energy transmission device (110; 110'), wherein the wireless energy receiving device (120; 120') and / or the wireless energy transmission device (110; 110') comprises: a first oscillator (605a) configured to output an in-phase (I) signal; a second oscillator (605b) configured to output a quadrature-phase (Q) signal having a phase difference of 90 degrees to the I signal, wherein each of the first and second oscillators comprises a resonator having at least one inductor and at least one capacitor, and a current varying block (640a, 640b) connected to the at least one inductor and configured to vary an amount of current flowing through the at least one inductor; and a monitoring device (116; 124) configured to monitor a frequency of the I and / or Q signal and to control the current variation block (640a, 640b) according to a monitoring result. [2] Wireless energy transmission system (100, 100a; 100b) according to claim 1, further comprising: a sensor configured to detect a magnetic field between the wireless power receiving device (120; 120') and the wireless power transmitting device (110; 110') and further control the current changing block (640a, 640b) according to a detection result. [3] Wireless energy transmission system (100, 100a; 100b) according to claim 1, wherein the resonator comprises: a first inductor pair having a first mutual inductance and comprising a first inductor and a second inductor; a second inductor pair having a second mutual inductance and having a third inductor and a fourth inductor; a capacitor connected between the first inductor and the third inductor; and a bias block (630a, 630b) configured to bias current, which flows through the first and third inductors, wherein the current changing block (640a, 640b) changes the current flowing through the second and fourth inductors. [4] The wireless power transmission system (100, 100a; 100b) of claim 3, wherein the at least one inductor of the first oscillator (605a) is configured perpendicular to the at least one inductor of the second oscillator (605b). [5] Wireless energy receiving device (120; 120'), comprising: a first oscillator (605a) configured to output an in-phase (I) signal; and a second oscillator (605b) configured to output a quadrature-phase (Q) signal having a phase difference of 90 degrees from the I signal, where both the first and second oscillators have: a first inductor pair having a first mutual inductance and comprising a first inductor and a second inductor; a second inductor pair having a second mutual inductance and a third inductor and a fourth inductor; and a capacitor connected between the first inductor and the third inductor, wherein both the first and second oscillators control a magnitude of received wireless energy by varying a resonant frequency by varying an amount of current flowing through the second and fourth inductors. [6] The wireless power receiving device (120; 120') of claim 5, wherein each of the first and second oscillators further comprises: a current varying block (640a; 640b) configured to vary the amount of current flowing through the second and fourth inductors. [7] The wireless power receiving device (120; 120') of claim 5, wherein the first and third inductors have the same inductance and the second and fourth inductors have the same inductance. [8] The wireless power receiving device (120; 120') of claim 5, wherein each of the first and second oscillators further comprises: a bias block (630a, 630b) configured to influence current flowing through the first and third inductors; cross-coupled transistors each connected between the first inductor and the bias block (630a, 630b), and between the third inductor and the bias block (630a, 630b); a transistor connected between the second inductor and the current varying block (640a, 640b); and a transistor connected between the fourth inductor and the current varying block (640a, 640b). [9] The wireless power receiving device (120; 120') of claim 8, wherein the Q signal output by the second oscillator (605b) is applied to gates of the transistors in the first oscillator (605a), and the I signal output by the first oscillator (605a) is applied to gates of the transistors in the second oscillator (605b). [10] The wireless power receiving device (120; 120') of claim 5, wherein at least one of the inductors in the first oscillator (605a) is configured perpendicular to at least one of the inductors in the second oscillator (605b). [11] Electronic system (700; 800; 900), comprising: a wireless energy receiving device (120) configured to wirelessly receive energy from a wireless energy transmitting device through a magnetic field and to generate received power; and a power unit (709; 805; 905) configured to receive the received power from the wireless energy receiving device (120) and to supply at least a portion of an internal power necessary for the operation of the electronic system, wherein the wireless energy receiving device (120) comprises: a first oscillator (605a) configured to output an in-phase (I) signal; and a second oscillator (605b) configured to output a quadrature-phase (Q) signal having a phase difference of 90 degrees from the I signal, and where both the first and second oscillators have: a resonator comprising at least one inductor and at least one capacitor; and a current varying block (640a; 640b) connected to the at least one inductor for varying an amount of current flowing through the at least one inductor. [12] The electronic system (700; 800; 900) of claim 11, wherein each of the first and second oscillators further comprises: a negative resistance block (615a, 615b) connected to the resonator to compensate for a positive resistance of the resonator; and a coupling circuit block (620a, 620b) connected to the at least one inductor to couple the first and second oscillators. [13] The electronic system (700; 800; 900) of claim 12, wherein the current varying block (640a, 640b) comprises at least two N-type metal oxide semiconductor (NMOS) transistors connected in parallel, one terminal of the at least two NMOS transistors being connected to the coupling circuit block (620a, 620b), and wherein the at least two NMOS transistors are selectively switched to vary the amount of current flowing through the at least one inductor in response to an input control signal applied to gates of the respective at least two NMOS transistors. [14] The electronic system (700; 800; 900) of claim 11, wherein the current variation block (640a, 640b) comprises: a power source configured to supply a predetermined current; a first N-type metal oxide semiconductor (NMOS) transistor having a terminal connected to the power source; and at least two NMOS transistors connected to a gate of the first NMOS transistor as a current mirror, wherein the at least two NMOS transistors are selectively switched in response to an input control signal to vary the amount of current flowing through the at least one inductor. [15] The electronic system (700; 800; 900) of claim 11, wherein the current variation block (640a, 640b) comprises: at least two current sources connected in parallel to supply a predetermined current; a first N-type metal oxide semiconductor (NMOS) transistor having a terminal connected to the at least two current sources; and a second NMOS transistor connected to a gate of the first NMOS transistor as a current mirror, wherein the at least two current sources are selectively switched in response to an input control signal to vary the amount of current flowing through the at least one inductor. [16] The electronic system (700; 800; 900) of claim 11, wherein the wireless energy receiving device (120) further comprises: a monitoring device (124) configured to monitor a frequency of the I and / or Q signal and generate a control signal; and a frequency adjuster (122) configured to change the frequency of the I and Q signals by changing the amount of current flowing through the at least one inductor in response to the control signal. [17] The electronic system (700; 800; 900) of claim 11, wherein the electronic system is one selected from the group consisting of a smartphone, a mobile phone, a personalized digital assistant (PDA), a portable multimedia player (PMP), and a tablet PC. [18] A method for wirelessly receiving energy using a wireless energy receiving device, the method comprising: Generating an in-phase (I) signal and a quadrature-phase (Q) signal having a phase difference of 90 degrees to the I signal using a quadrature oscillator (600) having at least one pair of inductors with mutual inductance; and Adjusting a resonant frequency by changing an amount of current flowing through an inductor in the at least one pair of inductors. [19] A method for wirelessly receiving energy according to claim 18, further comprising: Influencing current flowing in an inductor of the at least one pair of inductors using a predetermined bias current. [20] A method for wirelessly receiving energy according to claim 18, further comprising: Monitoring a frequency of the in-phase (I) signal and / or the quadrature-phase (Q) signal and providing a monitoring result, wherein adjusting the resonant frequency is performed by changing the amount of current flowing through the inductor in response to the monitoring result.

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