Magnetic resonance type wireless power supply device

Abstract

Provided is a magnetic resonance type wireless power supply device that supplies power in a non-contact manner by causing a power supply coil and a power reception coil to perform magnetic resonance using PT symmetry, and that can select and fix one of two resonance loops using a method that is not affected by the surrounding environment and does not restrict the design of the power supply coil and the power reception coil. A magnetic resonance type wireless power supply device using PT symmetry is provided with a power supply-side resonant circuit including a power supply coil and a power reception-side resonant circuit including a power reception coil, and an inverter (3) and a sensor (4) are connected to the power supply-side resonant circuit (3). The switching timing, which is the timing at which a switching element inside the inverter (3) is turned on or off, is determined on the basis of a pulse generated by a signal the phase relationship of which has been adjusted by the phase adjustment circuit (30), thereby selecting one of the two resonant rings.

Description

Technical Field

[0001] This invention relates to a magnetic resonance wireless power supply device that utilizes Parity-Time symmetry (hereinafter referred to as "PT symmetry") to supply power to the ground by making the power supply coil and the power receiving coil resonate magnetically instead of in contact. Background Technology

[0002] There are several known technologies for wireless power supply, including electromagnetic induction and magnetic resonance technologies. Among them, electromagnetic induction wireless power supply technology is used, for example, in mobile phone charging. It involves placing coils vertically, and based on the same principle as a transformer, it can only transmit power when the distance (transmission distance) between the power supply coil and the receiving coil is very short.

[0003] However, wireless power supply technology based on electromagnetic induction has a short transmission distance of only a few millimeters, which makes it impossible to achieve a large distance between the power supply coil and the receiving coil. Moreover, if the positions of the power supply coil and the receiving coil deviate or separate slightly, charging or power supply cannot be performed. In other words, it is susceptible to positional deviation. Therefore, it is difficult to apply to artificial devices such as artificial hearts installed inside the human body, or devices such as robotic arms that rotate in multiple directions or deviate from their axes.

[0004] Furthermore, wireless power supply technology using magnetic resonance has a longer transmission distance, ranging from a few centimeters to several meters. Therefore, compared to electromagnetic induction, it can achieve a greater distance between the power supply coil and the receiving coil, thus reaching a level close to practical application. However, it suffers from a sensitivity issue: transmission fails if the distance between the power supply coil and the receiving coil is not fixed at a constant value. Whether the distance is closer or farther, or if there is an angle, the transmission efficiency decreases, and the required power cannot be transmitted. In other words, this method also has poor resistance to positional deviations, making it unsuitable for devices that rotate in multiple directions or have axis deviations (rotating power supply objects), such as robotic arms.

[0005] Here, as one of the wireless power supply methods, there exists a wireless power supply technology that utilizes Parity-Time symmetry (hereinafter referred to as "PT symmetry"). This wireless power supply utilizing PT symmetry is a physical system with a non-Hermi Hamiltonian, and is a novel concept of wireless power supply first published in 2017 (see Non-Patent Literature 1).

[0006] When PT symmetry is maintained, the intrinsic energy of the Hamiltonian becomes real, and therefore non-Hermitian, but its behavior retains the energy characteristics of a Hermitian system. In this case, the energy transferred per unit time between the power supply and receiving resonant circuits no longer depends on the coupling coefficient between the two resonant circuits. As a result, even if the transmission distance varies, and even if the power supply and receiving coils are misaligned, as long as PT symmetry is maintained, the transmitted power and the power transmission efficiency remain constant.

[0007] Furthermore, to suppress variations in transmitted power and power transmission efficiency relative to transmission distance, various methods have been proposed for automatically adjusting the frequency of the inverter used as an AC power source (see Non-Patent Document 2). However, these control methods cannot make the transmitted power and power transmission efficiency completely independent of the transmission distance. This is because not all of these systems are designed as non-Hermitian physical systems, making it impossible to maintain PT symmetry.

[0008] Furthermore, the wireless power supply utilizing PT symmetry replaces the AC power supply of the previous magnetic field resonance wireless power supply technology with an inverter that behaves electrically like a negative resistor, that is, an inverter that behaves like a negative resistor.

[0009] This situation is disclosed as known technology in, for example, Patent Document 1. However, to elaborate further, the inverter exhibiting negative resistance is one in which the switching frequency and voltage amplitude are not predetermined. It has a circuit structure where the switching frequency is determined based on the apparent resonant frequency of the wireless power supply circuit as observed from the inverter's output. The switching frequency rapidly responds to the apparent resonant frequency of the wireless power supply circuit, which varies due to changes in the coil's transmission distance, positional deviation, etc. Here, the wireless power supply circuit is a circuit that includes a power supply-side resonant circuit, a power receiving-side resonant circuit, and all subsequent circuits connected to them. Furthermore, since the power supply-side resonant circuit and the power receiving-side resonant circuit interact, the apparent resonant frequency refers to the substantial resonant frequency that takes this interaction into account.

[0010] Furthermore, in wireless power supply utilizing PT symmetry, the aforementioned inverter is used to induce self-oscillation. The oscillation exhibits two modes, both of which maintain PT symmetry. These two modes will be explained in detail here. Figure 1 This is a diagram representing the equivalent circuit of the SP topology, which is consistent with Patent Document 1. Figure 14 Same diagram.

[0011] like Figure 1 As shown, the power supply side resonant circuit 1 and the power receiving side resonant circuit 2 of the SP topology can be represented as having mutual inductance k m L-coupled double resonant circuit. Furthermore, Figure 1 In this equation, L represents the self-inductance of both the power supply coil 11 and the receiving coil 21. L(1-k) m The values ​​() represent the leakage inductance of the power supply coil 11 and the receiving coil 21, respectively. Furthermore, r1' and r2' represent the winding resistances of the power supply coil 11 and the receiving coil 21, respectively. c This represents the iron loss equivalent resistance. C represents the capacitance of the capacitor (static capacitance). Figure 1 The circuit shown has two resonant loops ("the resonant loop of loop I" and "the resonant loop of loop II") for circulating the resonant current in a dual-resonant circuit. Furthermore, the resonant frequency of loop I is set as ω. l The resonant frequency of ring II is set as ω. h .

[0012] However, as shown in the experimental results of Non-Patent Document 1, the two oscillation modes (resonance rings) sometimes switch arbitrarily and unexpectedly during operation. When the switching of oscillation modes (resonance rings) occurs, the operation becomes unstable and power transmission itself becomes difficult, thus requiring a reliable method for selecting either oscillation mode (resonance ring).

[0013] Therefore, as a solution to this problem, Patent Document 1 proposes a method for selecting any one of the resonant rings in a magnetic resonance wireless power supply device that utilizes PT symmetry to supply power to the power supply coil and the receiving coil through magnetic resonance without contact.

[0014] Prior art literature Patent documents Patent Document 1: Japanese Patent Application Publication No. 2022-121324 Non-patent literature Non-patent literature 1: Sid Assawaworrarit, Xiaofang Yu & Shanhui Fan, “Robustwireless power transfer using a nonlinear parity-time-symmetric circuit”, Nature, 15 JUNE 2017, volume 546, pp. 387-390 Non-patent document 2: APSample, DTMeyer & JR Smith, "Analysis, experimental results, and range adaptation of magnetically coupled resonators for wireless power transfer", IEEE Trans. Ind. Electron., 2011, vol.58, no.2,pp.544-554 Non-patent document 3: J. Zhou, B. Zhang, W. Xiao, D. Qiu, and Y. Chen, "Nonlinear parity-time-symmetric model for constant efficiency wireless powertransfer: application to a drone-in-flight wireless charging platform", IEEETrans. Ind. Electron., Aug. 2019, vol.66, no.5, pp.4097-4107 Non-patent document 4: H. Ishida, T. Kyoden, and H. Furukawa, "Application of parity-time symmetry to low-frequency wireless power transfer system", IEEJJ. Ind. Appl., 2022, vol.11, no.1, pp.59-68 Summary of the Invention

[0015] The problem that the invention aims to solve However, in magnetic resonance wireless power supply devices such as Patent Document 1, the method of adjusting the Q value (selectivity) of the two resonant rings by designing the coils, thereby selecting either resonant ring, is used. Therefore, the design of the power supply coil and the receiving coil is constrained, and the coils cannot be made to have free shapes and sizes, which presents application challenges.

[0016] The present invention was made to solve the above-mentioned problems, and aims to provide a magnetic resonance type wireless power supply device that utilizes PT symmetry to supply power by making the power supply coil and the power receiving coil magnetically resonate without contact. The magnetic resonance type wireless power supply device can select and fix any one of the two resonant rings by means of a method that is not affected by the surrounding environment and whose design of the power supply coil and the power receiving coil is not restricted.

[0017] Solution for solving the problem To achieve the above objectives, the present invention provides a magnetic resonance wireless power supply device, comprising a power supply-side resonant circuit including a power supply coil and a power receiving-side resonant circuit including a power receiving coil. Utilizing Parity-Time symmetry, power is supplied non-contactly by causing the power supply coil and the power receiving coil to resonate magnetically. The device is characterized in that, when the power supply-side resonant circuit and the power receiving-side resonant circuit are considered as a dual-resonant circuit coupled to each other through mutual inductance, there are two resonant loops ("ring I" and "ring II") for circulating the resonant current in the dual-resonant circuit. An inverter is connected to the power supply-side resonant circuit. The inverter includes a sensor for detecting the current or magnetic field of the power supply coil. The inverter also includes a phase adjustment circuit that, based on the current phase of the power supply coil detected by the sensor or the magnetic field phase of the power supply coil, adjusts the phase relationship between the AC voltage applied to the power supply side resonant circuit and the AC current in the power supply coil. This allows the switching timing of the switching elements inside the inverter to be determined based on a pulse generated from a signal whose phase relationship has been adjusted using the phase adjustment circuit. This allows for the selection and fixing of either of the two resonant rings.

[0018] Invention Effects According to the present invention, in a magnetic resonance type wireless power supply device that utilizes PT symmetry and supplies power by magnetic resonance between a power supply coil and a receiving coil without contact, a phase adjustment circuit is provided for adjusting the phase relationship between the AC voltage applied to the power supply side resonant circuit and the AC current in the power supply coil. As a result, it is possible to select and fix either of the two resonant rings using a method that is not affected by the surrounding environment and does not restrict the design of the power supply coil and the receiving coil. Attached Figure Description

[0019] Figure 1 This is a diagram representing the equivalent circuit of the SP topology.

[0020] Figure 2 These are conceptual diagrams representing two representative types of circuit structures for wireless power supply utilizing the magnetic field resonance method of PT symmetry.

[0021] Figure 3 It represents the magnetic coupling coefficient k. m A coordinate graph showing the numerical calculation results of a typical example of the relationship between the transmission distance d between the two coils (power supply coil and power receiving coil).

[0022] Figure 4 It represents the resonant frequency ω of ring II. h and the resonant frequency ω of ring I l A coordinate graph showing the relationship between the transmission distance d between the two coils (power supply coil and power receiving coil).

[0023] Figure 5 This is a circuit diagram of a D-class inverter connected to a power supply side resonant circuit when used as a wireless power supply with PT symmetry.

[0024] Figure 6 It means Figure 5 A schematic diagram showing the phase relationship of each waveform in the power supply side resonant circuit.

[0025] Figure 7 This is the experimental result representing the phase relationship between the alternating current i1 and the input voltage v1.

[0026] Figure 8 This is a circuit diagram representing the equivalent circuit for wireless power supply connected to the inverter.

[0027] Figure 9 This is a circuit diagram illustrating an example of an inverter with a phase adjustment circuit and a power supply side resonant circuit according to Embodiment 1 of the present invention.

[0028] Figure 10 It means Figure 9 A schematic diagram of the voltage waveforms of each part of the phase adjustment circuit (preamplifier 36 and phase lag circuit 35) shown.

[0029] Figure 11 This is a circuit diagram illustrating an example of an inverter with a time lag circuit and a power supply side resonant circuit according to Embodiment 1 of the present invention.

[0030] Figure 12 This is a circuit diagram illustrating an example of an inverter with an all-pass filter and a power supply side resonant circuit according to Embodiment 1 of the present invention.

[0031] Figure 13 This is a circuit diagram illustrating an example of an inverter with a PLL (phase synchronization circuit) and a power supply side resonant circuit according to Embodiment 1 of the present invention.

[0032] Figure 14 This is a block diagram illustrating an example of the specific internal function of the PLL (phase synchronization circuit) in Embodiment 1 of the present invention.

[0033] Figure 15 This is a circuit diagram illustrating an example of an inverter and a power supply side resonant circuit having an all-pass filter and a PLL (phase synchronization circuit) according to Embodiment 1 of the present invention.

[0034] Figure 16 This is a coordinate graph showing the measured waveforms of the AC current i1 and the input voltage v1 when the input voltage v1 is adjusted to lead the phase relative to the AC current i1 in the actual device of Embodiment 1 of the present invention.

[0035] Figure 17 It means in Figure 16 In the phase relationship, a coordinate graph showing the result of measuring the change in resonant frequency when the distance d between the power supply coil 11 set in the power supply side resonant circuit 1 and the power receiving coil 21 set in the power receiving side resonant circuit 2, that is, the transmission distance d between the two coils, changes.

[0036] Figure 18 It is a coordinate graph showing the results of measuring the transmitted power when the transmission distance d between the two coils is varied. Detailed Implementation

[0037] This invention relates to a magnetic resonance wireless power supply device that utilizes Parity-Time symmetry (hereinafter referred to as "PT symmetry") to supply power to the ground by making the power supply coil and the power receiving coil resonate magnetically instead of in contact.

[0038] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0039] Implementation method 1. Figure 2 These are conceptual diagrams representing two representative types of circuit structures for wireless power supply utilizing PT symmetry and magnetic field resonance. Figure 2 In either of the circuit examples shown in (a) and (b), the power supply side resonant circuit 1 is connected to the inverter 3, which serves as the AC power source. On the other hand, a load resistor R is connected to the power receiving side resonant circuit 2. L The load. In these circuits, L1 represents the self-inductance of the power supply coil 11, C1 represents the electrostatic capacitance of the power supply side capacitor, L2 represents the self-inductance of the receiving coil 21, and C2 represents the electrostatic capacitance of the receiving side capacitor. Moreover, r1 and r2 represent the resistive components included in the power supply side resonant circuit 1 and the receiving side resonant circuit 2, respectively.

[0040] Figure 2 The circuit example shown in (a) is called an SS topology because the coil of the power supply side resonant circuit 1 is connected in series with the capacitor, and the coil of the power receiving side resonant circuit 2 is also connected in series with the capacitor. Figure 2In the circuit example shown in (b), the coil of the power supply side resonant circuit 1 is connected in series with the capacitor, and the coil of the power receiving side resonant circuit 2 is connected in parallel with the capacitor, hence the name SP topology. Non-patent document 3 discloses an example of wireless power supply that maintains PT symmetry in an SS topology, and non-patent document 4 discloses an example of wireless power supply that maintains PT symmetry in an SP topology.

[0041] Here, once again Figure 1 Taking the equivalent circuit of the SP topology shown as an example, the power supply side resonant circuit 1 and the power receiving side resonant circuit 2 of the SP topology can be represented as follows, with mutual inductance k m L-coupled double resonant circuit. Furthermore, Figure 1 In this equation, L represents the self-inductance of both the power supply coil 11 and the receiving coil 21. L(1-k) m The values ​​() represent the leakage inductance of the power supply coil 11 and the receiving coil 21, respectively. Furthermore, r1' and r2' represent the winding resistances of the power supply coil 11 and the receiving coil 21, respectively. c This represents the iron loss equivalent resistance. C represents the capacitance of the capacitor (electrostatic capacitance). In Figure 1 The circuit shown contains two resonant loops ("the resonant loop of loop I" and "the resonant loop of loop II") for circulating the resonant current in the double resonant circuit. Furthermore, the resonant frequency of loop I is set as ω. l Let the resonant frequency of ring II be ω. h .

[0042] Furthermore, in the wireless power supply device utilizing PT symmetry in Embodiment 1 of the present invention, as previously described, the self-oscillation of the inverter, and the existence of two oscillation modes, in which PT symmetry can be maintained, are the same as in the past. Additionally, as... Figure 1 , Figure 2 As shown, it is self-evident that the power supply side resonant circuit 1 includes a power supply coil 11 and the power receiving side resonant circuit 2 includes a power receiving coil 21.

[0043] Furthermore, in Figure 2 In either of the topologies shown in (a) and (b), the wireless power supply circuit observed from the output of inverter 3 forms a double resonant circuit with two resonant loops. Figure 2 The circuit diagram shown cannot derive a strict formula for the two resonant rings. Strictly speaking, this formula can be derived through coupling mode theory, and its derivation process is as shown in Non-Patent Document 4 (as shown in Non-Patent Document 4 by one of the applicants of this application). However, detailed explanations and derivation processes are omitted here, and only the results are recorded as shown in formulas (1) and (2).

[0044] [Formula 1] [Formula 2] That is, there exists ω as shown in formula (1). h The resonant ring with the resonant frequency and ω as shown in formula (2) l The resonant rings have the resonant frequency of ω. Furthermore, both resonant rings are at ω. h >ω l The relationship is as follows. ω0 is the inherent resonant angular frequency when the power supply side resonant circuit and the power receiving side resonant circuit are far apart and completely uncoupled, which can be expressed by formula (3). It should be noted that Γ in formulas (1) and (2) 20 and Γ L These are all parameters in Coupled Mode Theory (CMT parameters), which are described in detail in Patent Document 1 (as shown by one of the applicants of this application in Patent Document 1 and Non-Patent Document 4). However, due to their relatively minor relevance and lengthy definitions, detailed descriptions are omitted here.

[0045] [Formula 3] Additionally, k is a parameter called the coupling ratio, which is related to the number of energy exchanges per unit time between the power supply-side resonant circuit and the power receiving-side resonant circuit. Furthermore, the magnetic coupling coefficient k between the power supply coil and the power receiving coil can be used. m , as in formula (4), represents the coupling rate k.

[0046] [Formula 4] Here, for example, in Figure 2 In the case of the SP topology in (b), if formulas (1) and (2) are applied, it can be expressed as in formulas (5) and (6) below.

[0047] [Formula 5] [Formula 6] It should be noted that the above formulas (5) and (6) can also be approximated as formulas (7) and (8). In the description of Patent Document 1, their approximations, namely formulas (7) and (8), are used.

[0048] [[Formula 7] [Formula 8] From formulas (5) and (6), it can be seen that the resonant frequency ω of ring II is... h and the resonant frequency ω of ring I l Only the magnetic coupling coefficient k m The function of . In the case of complex coil shapes, it is difficult to control the magnetic coupling coefficient k. m The relationship between the distance d (transmission distance) between the power supply coil and the receiving coil is formalized, and is usually calculated numerically using a computer, while the magnetic coupling coefficient k... m The relationship between the transmission distance d between coils is generally inversely proportional. Figure 3 It represents the magnetic coupling coefficient k. m A coordinate graph showing the numerical calculation results of a typical example of the relationship between the transmission distance d between the two coils (power supply coil and power receiving coil).

[0049] like Figure 3 As shown, regarding the magnetic coupling coefficient k m The relationship between the transmission distance d between the two coils (the power supply coil and the receiving coil) can be numerically calculated, and therefore the resonant frequency ω of ring II can also be calculated according to formulas (5) and (6). h and the resonant frequency ω of ring I l The relationship between the transmission distance d between the two coils (power supply coil and power receiving coil). Figure 4 It represents the resonant frequency ω of ring II. h and the resonant frequency ω of ring I l A coordinate graph showing the relationship between the transmission distance d between the two coils (power supply coil and power receiving coil).

[0050] like Figure 4 As shown, when the transmission distance d between the two coils increases, the resonant frequency ω of ring II... h As the transmission distance d increases towards the lower direction, the resonant frequency ω of ring I... l Towards the direction of increasing height. Figure 4 In the example shown, when the transmission distance d between the two coils is around 70 mm, the resonant frequencies of the two resonant rings are the same. Beyond this point, the PT symmetry is not maintained, and therefore these are excluded from the discussion of this invention.

[0051] As mentioned earlier, in PT-symmetric wireless power supply, the inverter is made to self-oscillate, therefore the resonant frequency ω of ring II is selected. h and the resonant frequency ω of ring I l The resonant frequency ω of ring II can generate self-excited oscillation. However, when the transmission distance d changes during operation, if the resonant frequency ω of ring II... h The resonant frequency ω of ring Il An unexpected and sudden switch causes a sudden and large (discontinuous) change in the frequency of the self-excited oscillation, thus temporarily interrupting power transmission. Furthermore, the magnitude and efficiency of the transmitted power vary depending on the mode, therefore, the resonant frequency ω of ring II also presents an issue. h The resonant frequency ω of ring I l The switching can cause variations in the amount of power transmitted.

[0052] Therefore, in this invention, even if the transmission distance d varies, as long as the resonant ring is fixed at any one of the rings, the frequency of the self-excited oscillation can change smoothly (continuously), thus enabling stable wireless power supply. Based on this concept, and considering the resonant frequency ω of the ring II... h The resonant ring or the resonant frequency ω of ring I. l The purpose of selecting and fixing any one of the resonant rings is to set up a phase adjustment circuit in the circuit structure to make the voltage phase lead / lag relative to the current of the power supply coil 11.

[0053] First, the circuit structure of the inverter without the phase adjustment circuit of the present invention will be described. The inverter used for PT-symmetric wireless power supply uses a Class D inverter or a Class E inverter. Figure 5 This is a circuit diagram showing the connection of a Class D inverter, used as a PT-symmetric wireless power supply, to the power supply-side resonant circuit. Although in practice there exists... Figure 5 The power supply side resonant circuit 1 shown is wirelessly powered by a power receiving side resonant circuit and a load resistor connected to the power receiving side resonant circuit, but in this... Figure 5 The illustration is omitted. Figure 6 It means Figure 5 A schematic diagram showing the phase relationship of each waveform in the power supply side resonant circuit 1.

[0054] As described in the prior art, wireless power supply utilizing PT symmetry replaces the AC power source in conventional magnetic field resonance wireless power supply technology with an inverter that has the same electrical performance as a negative resistor, i.e., an inverter that performs as a negative resistor.

[0055] An inverter exhibiting negative resistance is an inverter whose switching frequency and voltage amplitude are not predetermined. It has a circuit structure where the switching frequency is determined based on the apparent resonant frequency of the wireless power supply circuit as observed from the inverter's output. The switching frequency rapidly follows the apparent resonant frequency of the wireless power supply circuit, which varies due to changes in the transmission distance between the two coils (power supply coil and receiving coil), positional deviations, etc. Furthermore, the wireless power supply circuit refers to a circuit that includes the power supply-side resonant circuit, the receiving-side resonant circuit, and all subsequent circuits connected to them. Moreover, since the power supply-side resonant circuit and the receiving-side resonant circuit interact, the apparent resonant frequency refers to the substantial resonant frequency that takes this interaction into account.

[0056] like Figure 5 As shown, the inverter 3 and the current sensor 4 are connected in the power supply side resonant circuit 1, which together form a negative resistance circuit. Furthermore, the components constituting the inverter 3 include a comparator 31, a gate driver 32, a high-side FET (field-effect transistor) 33, and a low-side FET (field-effect transistor) 34. The high-side FET 33 and the low-side FET 34 are switching elements within the inverter 3.

[0057] Towards Figure 5 When the comparator 31 receives a detection signal of the alternating current i1 flowing in the power supply coil 11 detected by the current sensor 4, and an input pulse is input to the gate driver 32 as the output of the comparator 31, the gate driver 32 outputs two-phase output pulses (first-phase output pulse and second-phase output pulse) with a phase difference of 180° to alternately energize / de-energize (turn on / off) the switching elements inside the inverter 3, namely the high-side FET 33 and the low-side FET 34. The input pulse input to the gate driver 32 is generated based on the alternating current i1 flowing in the power supply coil 11 or the alternating magnetic field generated by the power supply coil 11.

[0058] At this time, the switching timing of the output pulses alternately output from the gate driver 32 to the switching elements inside the inverter 3, namely the high-side FET 33 and the low-side FET 34, is determined based on the input pulses input to the gate driver 32. Here, "switching timing" refers to the moment when the switching elements inside the inverter 3, namely the high-side FET 33 and the low-side FET 34, are turned on or off. Furthermore, the aforementioned input pulses are generated by inputting a detection signal of the alternating current i1 detected by the current sensor 4 disposed between the inverter 3 and the power supply side resonant circuit 1 to the comparator 31.

[0059] That is, the output of inverter 3, i.e. the driving current of the power supply coil 11 of the power supply side resonant circuit 1, is fed back to the control side of inverter 3 to control the output current of inverter 3. This is called "feedback control".

[0060] Here, the detection signal for the AC current i1 is an AC voltage signal that is in phase with the AC current i1. In principle, the AC current i1 and the input voltage v1 of the power supply side resonant circuit are in phase (without phase difference), thus generating self-excited oscillation through positive feedback. This self-excited oscillation is used to excite the power supply coil to achieve wireless power supply.

[0061] However, in actual circuits, the AC current i1 and the input voltage v1 are not in phase. In reality, the voltage signal experiences a time lag during propagation in the circuit, thus the input voltage v1 becomes lagging in phase relative to the AC current i1. This phase difference is called the initial phase difference. It should be noted that the phase compensation circuit described in Patent Document 1 compensates for this initial phase difference, making the AC current i1 and the input voltage v1 in phase, and its purpose is entirely different from that of the invention in this application.

[0062] Furthermore, as mentioned earlier, while it is theoretically correct to make the AC current i1 and the input voltage v1 in phase, in practice, making them in phase would lead to the problem of frequent switching between the two resonant loops, as described above. Conversely, experiments show that when an intentional phase difference is set between the AC current i1 and the input voltage v1, stability is achieved in either resonant loop.

[0063] Figure 7 This represents the experimental results showing the phase relationship between the alternating current i1 and the input voltage v1. Figure 7 (a) shows the case where the input voltage v1 lags behind the AC current i1. Figure 7 (b) shows the case where the AC current i1 and the input voltage v1 are in phase. Figure 7 (c) shows the case where the input voltage v1 is in phase with respect to the AC current i1.

[0064] like Figure 7 As shown in (a), when the input voltage v1 lags behind the AC current i1, the resonant frequency ω of loop I is selected. l The resonant ring. For example... Figure 7 As shown in (b), when the AC current i1 and the input voltage v1 are approximately in phase, the resonant loop becomes unstable. Furthermore, as... Figure 7 As shown in (c), when the input voltage v1 leads the AC current i1, the resonant frequency ω of ring II is selected. h The resonant ring.

[0065] Next, the principle of selecting the resonant loop by adjusting the phase relationship between the AC current i1 and the input voltage v1 will be explained. As mentioned earlier, the inverter of the wireless power supply device of Embodiment 1 of the present invention oscillates self-excitedly by giving positive feedback to the current waveform of the AC current i1. Thus, the inverter can be regarded as an AC power supply with an unfixed oscillation frequency.

[0066] like Figure 5 As shown, inverter 3 is connected to the power supply side resonant circuit 1. Furthermore, the power receiving side resonant circuit 2 (see reference 1) is connected via magnetic coupling. Figure 1 , Figure 2 and load resistance R L (Reference Figure 1 , Figure 2 It is also indirectly connected to inverter 3.

[0067] The circuit observed from the output of inverter 3 forms a resonant circuit. Representing this resonant circuit as a simple equivalent circuit is as follows: Figure 8 As shown. Figure 8 This is a circuit diagram representing the equivalent circuit for wireless power supply connected to an inverter. Here, the resistance component is represented by R, the inductance component by L, and the capacitance component by C.

[0068] The inverter operates at the resonant frequency ω c When self-excited oscillation occurs, the sizes of the inductive reactor and the capacitive reactor need to satisfy the following formula (9).

[0069] [Formula 9] Therefore, the reactor component of the resonant circuit observed from the inverter output is zero, which is equivalent to the circuit in which only resistor R is connected to the inverter. This is the original equivalent circuit while maintaining PT symmetry. Furthermore, as mentioned earlier, in the original equivalent circuit, only resistor R is connected to the inverter, so the AC current i1 and the input voltage v1 are in phase.

[0070] However, in this invention, a phase difference is forcibly created between the AC current i1, which is originally in phase, and the input voltage v1.

[0071] For example, such as Figure 7 As shown in (a), when the input voltage v1 lags behind the AC current i1, the equivalent circuit connected to the inverter becomes capacitive. In other words, when the input voltage v1 lags behind the AC current i1, the resonant frequency ω changes from its original resonant frequency ω c Slightly deviating from this, one could say that the equivalent circuit connected to the inverter becomes capacity-dependent.

[0072] On the other hand, such as Figure 7As shown in (c), when the input voltage v1 leads the AC current i1, the resonant frequency ω changes from its original resonant frequency ω c Slightly off-center, the equivalent circuit connected to the inverter becomes inductive.

[0073] However, the impedance Z of the equivalent circuit connected to the inverter can be expressed as formula (10). Moreover, the condition for inductance is formula (11).

[0074] [Formula 10] [Formula 11] Furthermore, according to formula (9), the inductive component L can be expressed as in formula (12). Therefore, if formula (12) is substituted into formula (11), the condition for inductance becomes formula (13).

[0075] [Formula 12] [Formula 13] Thus, if the input voltage v1 leads the alternating current i1, the resonant frequency ω at this time is higher than the original resonant frequency ω. c Slightly higher.

[0076] As mentioned earlier, the resonant frequency ω c It is the resonant frequency ω of ring II h Or the resonant frequency ω of ring I l Moreover, due to being in ω h >ω l The relationship thus makes ω>ω as shown in formula (13) c The sufficient condition for the relationship to be satisfied is ω > ω. h However, ω is greater than ω h Slightly higher frequencies, therefore ω becomes the same as ω h Compared to a roughly constant frequency, that is, when the input voltage v1 is led by the alternating current i1, the resonant frequency ω of ring II is selected. h The resonant ring.

[0077] On the other hand, the condition for capacity is formula (14). Moreover, according to formula (9) and formula (14), the condition for capacity becomes formula (15).

[0078] [Formula 14] [Formula 15] Thus, if the input voltage v1 lags behind the alternating current i1, the resonant frequency ω at this time will be higher than the original resonant frequency ω. c Slightly lower.

[0079] As mentioned earlier, the resonant frequency ω c It is the resonant frequency ω of ring II h Or the resonant frequency ω of ring I l Moreover, due to being in ω h >ω l The relationship is such that ω < ω as shown in formula (15) c The sufficient condition for the relationship to be satisfied is ω < ω. l However, ω is greater than ω l Slightly lower frequencies, therefore ω becomes the same as ω l Compared to a nearly constant frequency, that is, when the input voltage v1 lags behind the alternating current i1, the resonant frequency ω of ring I is chosen. l The resonant ring.

[0080] Next, a practical circuit example will be described. As mentioned earlier, when attempting to intentionally set a phase difference between the AC current i1 and the input voltage v1, it was confirmed that stability could be achieved in any resonant loop (for experimental results, see the following section). Figures 16-18 Therefore, in order to select the resonant frequency ω of fixed ring II... h The purpose of the resonant loop is to ensure that the input voltage v1 is ahead of the AC current i1. This can be achieved by simply inserting a phase lead circuit before inputting the AC current detected by the current sensor to the comparator. However, the phase lead circuit also functions as a high-pass filter, thus allowing high-frequency noise components to pass preferentially, thereby worsening the S / N ratio and making it unsuitable for stable operation.

[0081] On the other hand, the phase lag circuit also functions as a low-pass filter, shielding high-frequency noise components, thus making it suitable for stable operation. Of course, being a phase lag circuit, it cannot be used to create a phase-leading circuit. Therefore, in practical circuits, such as... Figure 9 As shown, the phase adjustment circuit 30 is constructed by combining the preamplifier 36 and the phase lag circuit 35, thereby achieving phase lead. By selecting and fixing either of the two resonant rings, stable operation can be achieved.

[0082] Figure 9 This is a circuit diagram illustrating an example of an inverter with a phase adjustment circuit and a power supply side resonant circuit according to Embodiment 1 of the present invention. Figure 9As shown, the power supply side resonant circuit 1 is connected to the inverter 3. Components within the inverter 3 include a comparator 31, a gate driver 32, a high-side FET (field-effect transistor) 33, and a low-side FET (field-effect transistor) 34. This is consistent with... Figure 5 The circuit diagram shown is the same.

[0083] In addition, Figure 9 Although only the power supply side resonant circuit 1 and the inverter 3 and current sensor 4 connected to it are shown in the diagram, as a premise, with Figure 1 , Figure 2 Similarly, the magnetic resonance wireless power supply device includes a power supply side resonant circuit 1 containing a power supply coil 11 and a power receiving side resonant circuit 2 containing a power receiving coil 21. Utilizing PT symmetry (Parity-Time symmetry), power is supplied to the power supply coil 11 and the power receiving coil 21 through magnetic resonance without physical contact. When the power supply side resonant circuit 1 and the power receiving side resonant circuit 2 are regarded as a double resonant circuit coupled to each other through mutual inductance, there are two resonant loops ("the resonant loop of loop I" and "the resonant loop of loop II") that supply the resonant current circulation in the double resonant circuit.

[0084] However, in Figure 9 In the case of the circuit, specifically in an example of the circuit of Embodiment 1 of the present invention, before the input to the comparator 31 provided inside the inverter 3, a phase adjustment circuit 30 equipped with a preamplifier (inverting amplifier circuit) 36 and a phase lag circuit 35 is provided. Before the AC current i1 based on the detection of the current or magnetic field of the power supply coil 11 is input to the comparator 31, the AC current i1 is delayed by more than 180° by the phase adjustment circuit 30 (inverting amplifier circuit 36 ​​and phase lag circuit 35) and input to the comparator 31, thereby performing phase control by leading the phase. As a result, it is possible to select and fix the "resonant ring II" from the two resonant rings.

[0085] That is, if not set Figure 9 In the phase adjustment circuit 30 (preamplifier (inverting amplifier circuit) 36 and phase lag circuit 35), when the AC current i1 flowing to the power supply coil 11 detected by the current sensor 4 is input to the comparator 31 of the inverter 3, and the input pulse that serves as the output of the comparator 31 is input to the gate driver 32, the gate driver 32 outputs two-phase output pulses (first-phase output pulse and second-phase output pulse) with a phase difference of 180° to alternately energize / de-energize (turn on / off) the switching elements inside the inverter 3, namely the high-side FET 33 and the low-side FET 34. The input pulse input to the gate driver 32 is generated based on the AC current i1 flowing to the power supply coil 11 or the AC magnetic field generated by the power supply coil 11.

[0086] However, in Figure 9 In the process of inputting to comparator 31, a preamplifier (inverting amplifier circuit) 36 and a phase lag circuit 35 are set up. Before the AC current i1, based on the detection of current or magnetic field in power supply coil 11, is input to comparator 31, the inverting amplifier circuit 36 ​​and the phase lag circuit 35 input a signal with AC current i1 lagging by more than 180° to comparator 31. When an input pulse, which is the output of comparator 31, is input to gate driver 32, the gate driver 32 outputs two-phase output pulses (first phase output pulse, second phase output pulse) with a phase difference of 180° to alternately energize / de-energize (turn on / off) the switching elements inside inverter 3, namely the high-side FET 33 and the low-side FET 34, and the input pulse generated to gate driver 32 based on AC current i1 in power supply coil 11 or AC magnetic field generated in power supply coil 11, and the input pulse generated to gate driver 32. Figure 5 The inverter shown is the same as inverter 3.

[0087] At this time, the switching timing of the output pulses alternately output from the gate driver 32 to the switching elements inside the inverter 3, namely the high-side FET 33 and the low-side FET 34, is determined based on the input pulses input to the gate driver 32. Here, as mentioned earlier, "switching timing" is the moment when the switching elements inside the inverter 3, namely the high-side FET 33 and the low-side FET 34, are turned on or off. Furthermore, the detection signal of the AC current i1 detected by the current sensor 4 located between the inverter 3 and the power supply side resonant circuit 1, after phase adjustment by the preamplifier (inverting amplifier circuit) 36 and the phase lag circuit 35, is input to the comparator 31 to generate the aforementioned input pulses.

[0088] That is, in Figure 9 In this case, the switching timing of the output pulses alternately output from the gate driver 32 to the switching elements inside the inverter 3, namely the high-side FET 33 and the low-side FET 34, is determined based on the signal after phase control by feedback control of the current phase or magnetic field phase of the power supply coil 11 detected by the current sensor 4, that is, the input pulse generated by the input of the signal after the phase relationship is adjusted by the phase adjustment circuit 30 to the comparator 31.

[0089] Here, the preamplifier 36 is configured as an inverting amplifier circuit. Therefore, when the detection signal of the AC current i1 is input to the preamplifier 36, as... Figure 10 As shown, the phase of the output signal is reversed by 180° relative to the input signal. Figure 10 It means Figure 9The diagram shows the voltage waveforms of each part of the phase adjustment circuit 30 (preamplifier 36 and phase lag circuit 35). Then, an operational amplifier is used to further phase-lag the output of the phase lag circuit (low-pass filter) 35. For example, if the phase lag circuit 35 produces a 130° phase lag, the phase lag including the preamplifier 36 becomes 180 + 130 = 310°. That is, a lag of one cycle (360°) results in a phase lead of 360 - 310 = 50°, thus equivalently achieving phase lead. That is, the AC current i1 is lagging by more than 180° before being input to the comparator 31.

[0090] In addition, Figure 9 The text describes the use of inverter 3 and current sensor 4 as a negative resistive circuit connected to the power supply side resonant circuit 1. However, a magnetic sensor can also be used instead of current sensor 4. This is because the current phase is consistent with the magnetic field phase. Therefore, current can be detected by current sensor 4, and the alternating current can be detected based on the current phase. Similarly, magnetic sensor can be used to detect the magnetic field, and the alternating current can be detected based on the magnetic field phase. In other words, any sensor capable of detecting either the current or the magnetic field of the power supply coil 11 of the power supply side resonant circuit 1, as part of the negative resistive circuit formed together with inverter 3, will suffice. This point is further elaborated in the original text. Figure 5 , Figure 8 The following Figure 11 The same applies in the future.

[0091] That is, the Figure 9 The circuit shown is a device for self-excited oscillation of the inverter 3 connected to the power supply side resonant circuit 1, by detecting the current or magnetic field of the power supply coil 11, and based on this current or magnetic field, detecting the zero-crossing of the voltage or current of the power supply coil 11. Furthermore, the resonant frequency ω of the ring II is fixed for selection. h The purpose of the resonant loop ("resonant loop of loop II") is to make the voltage phase lead relative to the current of the power supply coil 11. Before inputting the AC current i1 detected by the current sensor 4 or magnetic sensor (not shown) of the power supply coil 11 into the comparator 31 in the inverter 3, a preamplifier (inverting amplifier circuit) 36 and a phase lag circuit 35 are inserted to lag it by more than 180°, thereby controlling the phase lead. That is, by adjusting the phase lag to more than 180°, the phase lead is achieved. As a result, the problem of weak noise immunity and unstable operation of the phase lead control can be solved.

[0092] Thus, the inverter 3 and the sensor that detects the current or magnetic field of the power supply coil 11 are connected to the resonant circuit 1 on the power supply side. Figure 9The inverter 3 includes a current sensor 4, which is a current sensor. The inverter 3 has a phase adjustment circuit 30 that controls the phase by feedback control of leading or lagging phase based on the current phase of the current in the power supply coil 11 detected by the sensor (or the magnetic field phase based on the magnetic field of the power supply coil 11). That is, the phase adjustment circuit 30 can adjust the phase relationship between the AC voltage applied to the power supply side resonant circuit 1 and the AC current in the power supply coil 11, so that the switching timing of the switching element inside the inverter 3 is determined based on the pulse generated by the signal after the phase relationship is adjusted by the phase adjustment circuit 30, thereby selecting and fixing one of the two resonant rings.

[0093] In addition, Figure 9 In the illustrated embodiment (circuit), a comparator 31 is provided inside the inverter 3, and a phase lag circuit 35, serving as a phase adjustment circuit 30, is provided before the input of the comparator 31. Furthermore, the inverter 3 selects the "resonance ring of ring II" among the two resonant rings for the phase lag circuit 35, based on the sensor (in... Figure 9 Before the AC current of the current or magnetic field in the power supply coil 11 detected by the current sensor 4 is input to the comparator 31, the AC current is delayed by more than 180° before being input to the comparator 31. Thus, the phase of the AC voltage applied to the power supply side resonant circuit 1 is advanced relative to the AC current in the power supply coil 11, that is, the phase relationship is adjusted by the phase advance.

[0094] exist Figure 9 In the illustrated embodiment (circuit), as a specific example of the phase adjustment circuit 30, a low-pass filter using an operational amplifier is used as the phase lag circuit 35. However, a large phase lag of approximately 130° is generated in the low-pass filter, which can be expected to result in a small gain (output amplitude / input amplitude) and a small amplitude of the output signal. One solution to this problem is to replace the low-pass filter with a time lag circuit.

[0095] Figure 11 This is a circuit diagram illustrating an example of an inverter with a time lag circuit and a power supply-side resonant circuit according to Embodiment 1 of the present invention. Figure 11 As shown, the power supply side resonant circuit 1 is connected to the inverter 3. Components within the inverter 3 include a comparator 31, a gate driver 32, a high-side FET (field-effect transistor) 33, and a low-side FET (field-effect transistor) 34. This is consistent with... Figure 5 and Figure 9 The circuit diagram shown is the same.

[0096] However, in Figure 11In the case of the circuit, that is, in another example of the circuit of Embodiment 1 of the present invention, a preamplifier (inverting amplifier circuit) 36 is provided before the input of the comparator 31 provided inside the inverter 3, and a time lag circuit 37 is provided after the output of the comparator 31 to perform phase control by controlling the lag time. Figure 11 In this case, the phase adjustment circuit 30 includes at least a time lag circuit 37.

[0097] That is, the Figure 11 The circuit shown is designed to fix the resonant frequency ω of loop II. h The purpose of the resonant ring (“resonant ring of ring II”) is to make the phase of the voltage lead relative to the current of the power supply coil 11. The AC current i1 detected by the current sensor 4 or magnetic sensor (not shown) of the power supply coil 11 is input to the comparator 31 in the inverter 3. After the output of the comparator 31, a time lag circuit 37 is inserted to control the phase by controlling the lag time.

[0098] A time lag circuit 37, consisting of a NOT-type logic element with a Schmitt trigger and an RC integrator, is connected in multiple stages to the downstream end of the comparator 31, thereby producing a relatively large phase lag of approximately 130°. That is, actual time control based on the NOT circuit and the RC integrator is implemented as the control of the switching signal input to the comparator 31, thus solving the problem of frequency dependence of phase lag in analog circuits. It should be noted that the logic element does not necessarily need to be a Schmitt trigger. Furthermore, the logic element can be replaced by a buffer circuit instead of a NOT-type one.

[0099] Thus, in Figure 11 In the illustrated embodiment (circuit), a comparator 31 is provided inside the inverter 3, based on the sensor (in Figure 11 The alternating current of the power supply coil 11, or the magnetic field detected by the current sensor 4, is input to the comparator 31. After the output of the comparator 31, a time lag circuit 37 is set as a phase adjustment circuit 30. Furthermore, the inverter 3 controls the phase relationship by controlling the lag time based on the time lag circuit 37, thereby selecting and fixing either of the two resonant rings.

[0100] exist Figure 9 and Figure 11In the actual circuit example, a current sensor 4 is installed on the connection line of the power supply coil 11 to detect the current in the power supply coil 11 (the current in the power supply side resonant circuit 1), thereby detecting the phase of the alternating current i1. The same effect can be achieved by installing a magnetic sensor (not shown) near the power supply coil 11 to detect the magnetic field of the power supply coil 11 (the magnetic field of the power supply side resonant circuit 1). As the magnetic sensor, in addition to a Hall element, it can also be a magnetic sensor with the wires formed in a loop, called a loop coil. It should be noted that in this case, the inverter 3 and the magnetic sensor constitute the aforementioned negative resistive circuit.

[0101] Thus, in Figure 9 In this process, the phase is controlled by inserting a phase hysteresis circuit (low-pass filter) 35 before the comparator 31. Figure 11 In this embodiment, the phase is controlled by inserting a time lag circuit 37 after the comparator 31. Alternatively, other conceivable embodiments could be considered, such as replacing... Figure 11 The time lag circuit 37 shown uses a circuit that controls only the phase, called an all-pass filter.

[0102] Figure 12 This is a circuit diagram illustrating an example of an inverter with an all-pass filter and a power supply-side resonant circuit according to Embodiment 1 of the present invention. Figure 12 As shown, an inverter 3 is connected to the resonant circuit 1 on the power supply side. Components within the inverter 3 include a comparator 31, a gate driver 32, a high-side FET (field-effect transistor) 33, and a low-side FET (field-effect transistor) 34. This is consistent with... Figure 5 , Figure 9 , Figure 11 The circuit diagram shown is the same.

[0103] However, in Figure 12 In the case of the circuit, that is, in another example of the circuit of Embodiment 1 of the present invention, a preamplifier (inverting amplifier circuit) 36 is provided before the input of the comparator 31 provided inside the inverter 3, and an all-pass filter 38 is provided after the output of the comparator 31, through which phase control is performed.

[0104] That is, the Figure 12 The circuit shown is designed to fix the resonant frequency ω of loop II. h The purpose of the resonant ring (“resonant ring of ring II”) is to make the voltage phase lead relative to the current of the power supply coil 11. The alternating current i1 detected by the current sensor 4 or magnetic sensor (not shown) of the power supply coil 11 is input to the comparator 31 in the inverter 3, and a full-pass filter 38 is inserted after the output of the comparator 31 for phase control.

[0105] Thus, in Figure 12 In the illustrated embodiment (circuit), a comparator 31 is provided inside the inverter 3 to compare the signal based on the sensor (in... Figure 12 The alternating current of the power supply coil 11, detected by the current sensor 4, or the magnetic field, is input to the comparator 31, and a full-pass filter 38 is set after the output of the comparator 31 as a phase adjustment circuit 30. Furthermore, the inverter 3 controls the phase relationship by adjusting the phase relationship through the full-pass filter 38, thereby selecting and fixing either of the two resonant rings.

[0106] In addition, such as Figure 13 As shown, it can also be considered to replace Figure 11 The time lag circuit 37 shown Figure 12 The method shown is to use a PLL (phase synchronization circuit) 39 to control the phase of the all-pass filter 38. Figure 13 This is a circuit diagram illustrating an example of an inverter with a PLL (phase synchronization circuit) and a power supply side resonant circuit according to Embodiment 1 of the present invention. Figure 13 As shown, an inverter 3 is connected to the resonant circuit 1 on the power supply side. Components within the inverter 3 include a comparator 31, a gate driver 32, a high-side FET (field-effect transistor) 33, and a low-side FET (field-effect transistor) 34. This is consistent with... Figure 5 , Figure 9 , Figure 11 , Figure 12 The circuit diagram shown is the same.

[0107] However, in Figure 13 In the case of the circuit, that is, in another example of the circuit of Embodiment 1 of the present invention, a preamplifier (inverting amplifier circuit) 36 is provided before the input of the comparator 31 provided inside the inverter 3, and a PLL (phase synchronization circuit) 39 is provided after the output of the comparator 31, through which phase control is performed.

[0108] That is, the Figure 13 The circuit shown is designed to fix the resonant frequency ω of loop II. h The purpose of the resonant ring (“resonant ring of ring II”) is to make the voltage phase lead relative to the current of the power supply coil 11. The alternating current i1 detected by the current sensor 4 or magnetic sensor (not shown) of the power supply coil 11 is input to the comparator 31 in the inverter 3, and a PLL (phase synchronization circuit) 39 is inserted after the output of the comparator 31. The phase lead / lag is controlled by the PLL (phase synchronization circuit) 39, thereby performing phase control.

[0109] Thus, in Figure 13In the illustrated embodiment (circuit), a comparator 31 is provided inside the inverter 3 to compare the signal based on the sensor (in... Figure 13 The alternating current of the power supply coil 11, or the magnetic field detected by the current sensor 4, is input to the comparator 31, and a PLL (phase synchronization circuit) 39, which serves as a phase adjustment circuit 30, is set after the output of the comparator 31. The PLL (phase synchronization circuit) 39 causes the phase of the alternating voltage applied to the power supply side resonant circuit 1 to lead or lag behind the phase of the alternating current in the power supply coil 11. As a result, the inverter 3 controls the adjustment of the phase relationship, thereby selecting and fixing either of the two resonant rings.

[0110] Figure 14 This is a block diagram illustrating an example of the specific internal function of the PLL (phase synchronization circuit) 39. For example... Figure 14 As shown, the PLL (phase synchronization circuit) 39 includes at least a PFD (phase detector) 91 and a VCO (voltage controlled oscillator) 92. The PFD 91 calculates the phase difference between the input signal, which serves as a reference frequency, and the feedback signal output from the VCO 92, whose frequency varies according to the voltage. By inputting this phase difference to the VCO 92, the input signal and output signal are synchronized. Therefore, by applying an appropriate compensation voltage to the input voltage of the VCO 92, the frequency range of the PLL 39's output signal can be limited.

[0111] For example, the resonant frequency ω of ring II h The frequency range is 70kHz~90kHz, and the resonant frequency ω of ring I is... l When the frequency range is 50kHz to 70kHz, if the frequency range of the output signal of PLL (phase synchronization circuit) 39 is 70kHz to 90kHz, then the resonant frequency ω of ring I will not occur. l The operation is such that, therefore, at the resonant frequency ω of ring II... h The stability of the operation is improved. That is, by controlling the input voltage of the VCO (voltage controlled oscillator) 92, the oscillation frequency of the VCO 92 is limited, and by limiting the frequency range of the output signal of the PLL (phase synchronization circuit) 39, the stability of the operation when either of the two resonant rings is selected can be improved.

[0112] Here, the preamplifier (inverting amplifier circuit) 36 will be used to make the power based on the power supplied by the preamplifier (inverting amplifier circuit) 36. Figure 13The inverted AC signal of the current detected by the current sensor 4 is input to comparator 31. The input pulse generated in comparator 31 is the input signal of PLL (phase synchronization circuit) 39. Therefore, when the output signal of PLL 39 is input to gate driver 32, compared to positive feedback without phase control, the frequency or phase can be controlled by controlling the input voltage of VCO (voltage controlled oscillator) 92 (controlling the control value of VCO 92). Using this, the resonant frequency ω of fixed ring II can be selected. h Or the resonant frequency ω of ring I l Any one of them can be used as the resonant frequency of the power supply side resonant circuit 1. Furthermore, as another method, the oscillation frequency of the VCO (voltage-controlled oscillator) 92 of the PLL (phase synchronization circuit) 39 can be limited and controlled to be the resonant frequency ω of ring II only. h The resonant frequency ω of oscillation or only ring I l oscillation.

[0113] This limits the variation range of the oscillation frequency of the VCO (voltage-controlled oscillator) 92 within the PLL (phase synchronization circuit) 39, ensuring that the resonant frequency ω of ring I is within the range of the PLL 39. l When oscillation is absolutely impossible, the only viable option is the resonant frequency ω of ring II. h Therefore, it is possible to forcibly select and fix the resonant frequency ω of ring II. h .

[0114] That is, by using the PLL (phase synchronization circuit) 39 which applies frequency limitation to the VCO (voltage controlled oscillator) 92, the output frequency of the PLL (phase synchronization circuit) 39 can be limited, thus the resonant ring can be fixed to any one of them, and unstable switching can be prevented.

[0115] This prevents the current loop from switching arbitrarily due to changes in the position of the power supply coil and the receiving coil in wireless power supply.

[0116] As described above, by adding a PLL (phase synchronization circuit) 39, not only can phase control be performed through the PLL, but phase fluctuations can also be reduced to achieve stable operation, thus also having the advantage of improving operational stability.

[0117] Furthermore, such as Figure 15 As shown, it can also be considered to replace Figure 11 The time lag circuit 37 shown Figure 12 The all-pass filter 38 shown, or Figure 13 The method shown uses both the PLL (phase synchronization circuit) 39 and the all-pass filter 38 to control the phase. Figure 15 This is a circuit diagram illustrating an example of an inverter and a power supply side resonant circuit having an all-pass filter and a PLL (phase synchronization circuit) according to Embodiment 1 of the present invention. Figure 15 As shown, an inverter 3 is connected to the resonant circuit 1 on the power supply side. Components within the inverter 3 include a comparator 31, a gate driver 32, a high-side FET (field-effect transistor) 33, and a low-side FET (field-effect transistor) 34. This is consistent with... Figure 5 , Figure 9 , Figure 11 , Figure 12 , Figure 13 The circuit diagram shown is the same.

[0118] Figure 16 This is a coordinate graph showing the measured waveforms of the AC current i1 and the input voltage v1 when the input voltage v1 is adjusted to be in a leading phase relative to the AC current i1 in the actual device of Embodiment 1 of the present invention. The dashed line represents the AC current i1, and the solid line represents the input voltage v1. That is, Figure 16 The phase difference between the AC voltage applied to the power supply side resonant circuit 1 and the AC current in the power supply coil 11 is shown.

[0119] in addition, Figure 17 It means in Figure 16 In the phase relationship, the coordinate graph shows the result of measuring the change in resonant frequency when the distance d between the power supply coil 11 set in the power supply side resonant circuit 1 and the power receiving coil 21 set in the power receiving side resonant circuit 2 changes. The ● symbol represents the experimental result and the dashed line represents the calculation result.

[0120] In the experiment, it was confirmed that... Figure 16 When the phase difference is 30-35 degrees, that is, when the AC voltage v1 is set to lead the AC current i1 by 30-35 degrees, as shown... Figure 17 As shown, the resonant frequency ω of ring II is stably chosen to be fixed. h .observe Figure 17 Therefore, it can be seen that, at any transmission distance, that is, even when the transmission distance d varies, the resonant frequency ω of ring II can always be selected as constant. h The resonant ring.

[0121] Figure 18 This is a coordinate graph showing the measured power transmission results when the transmission distance d between the two coils is varied. ● indicates experimental results, and dashed lines indicate calculated results. Observation Figure 18 It can be confirmed that power supply can always be provided regardless of the transmission distance, that is, even if the transmission distance d changes.

[0122] As described above, according to the present invention, in a magnetic resonance type wireless power supply device that utilizes PT symmetry and supplies power through magnetic resonance between a power supply coil and a receiving coil without physical contact, by providing a phase adjustment circuit for adjusting the phase, the resonant ring can be selected and fixed without being affected by the surrounding environment and without restricting the design of the power supply coil and the receiving coil. That is, without being affected by the surrounding environment, and without affecting the selection of suitable frequencies, coil core shapes, materials, etc. (without requiring adjustments to the coil design), the design of the power supply coil and the receiving coil is not restricted, and either resonant ring can be selected and fixed from two resonant rings, allowing the coil to have a free shape and size.

[0123] It should be noted that, within the scope of this invention, any structural elements of the embodiments can be modified or omitted.

[0124] Industrial availability The magnetic resonance wireless power supply device of the present invention is not only suitable for short-range wireless power supply such as charging mobile phones, but also widely applicable to wireless power supply in various environments such as underwater drones in water-filled environments and environments with a lot of metal in the surrounding area, such as powering equipment in factories.

[0125] Symbol Explanation 1. Power supply side resonant circuit 2. Resonant circuit on the receiving side 3 Inverter 4 Current Sensor 11 Power supply coil 21 Receiving coil 30 Phase Adjustment Circuit 31 Comparator 32 Gate Drivers 33 High-side FET 34 Low-side FET 35. Phase lag circuit 36. Preamplifier (inverting amplifier circuit) 37 Time Delay Circuit 38 All-pass filter 39 PLL (Phase Synchronization Circuit) 91 PFD (Phase Detector) 92 VCO (Voltage Controlled Oscillator)

Claims

1. A magnetic resonance type wireless power supply device that has a power supply side resonance circuit including a power supply coil and a power receiving side resonance circuit including a power receiving coil, performs power supply non-contact by making the power supply coil and the power receiving coil perform magnetic resonance by parity-time symmetry, characterized in that, when the power supply side resonance circuit and the power receiving side resonance circuit are regarded as a double resonance circuit that is coupled to each other by mutual inductance, there are two resonance loops, i.e., a "resonance loop of loop I" and a "resonance loop of loop II", through which resonance currents in the double resonance circuit circulate, in the power supply side resonance circuit, an inverter and a sensor that detects a current or a magnetic field of the power supply coil are connected, the inverter has a phase adjustment circuit that adjusts a phase relationship between an alternating voltage applied to the power supply side resonance circuit and an alternating current in the power supply coil based on a current phase of the current of the power supply coil detected by the sensor or a magnetic field phase of the magnetic field of the power supply coil, the timing at which a switching element inside the inverter is turned on or off, i.e., switching timing, is determined based on a pulse generated from a signal after the phase relationship is adjusted by the phase adjustment circuit, and thereby a fixed one of the two resonance loops is selected from the two resonance loops.

2. The magnetic resonance type wireless power supply device according to claim 1, characterized in that, in the inverter, a comparator is provided inside, and a phase hysteresis circuit that is the phase adjustment circuit is provided before an input to the comparator, the phase hysteresis circuit inputs an alternating current based on the current or the magnetic field of the power supply coil detected by the sensor to the comparator after making the alternating current lag more than 180° for the purpose of selecting the "resonance loop of loop II" of the two resonance loops, and thereby the phase of the alternating voltage applied to the power supply side resonance circuit is advanced with respect to the alternating current in the power supply coil, and the inverter performs control that adjusts the phase relationship by the advanced phase.

3. The magnetic resonance type wireless power supply device according to claim 1, characterized in that, in the inverter, a comparator is provided inside, an alternating current based on the current or the magnetic field of the power supply coil detected by the sensor is input to the comparator, and a time hysteresis circuit that is the phase adjustment circuit is provided after an output from the comparator, the inverter performs control that adjusts the phase relationship by a control based on a lag time of the time hysteresis circuit.

4. The magnetic resonance type wireless power supply device according to claim 1, characterized in that, in the inverter, a comparator is provided inside, an alternating current based on the current or the magnetic field of the power supply coil detected by the sensor is input to the comparator, and an all-pass filter that is the phase adjustment circuit is provided after an output from the comparator, the inverter performs control that adjusts the phase relationship by the all-pass filter.

5. The magnetic resonance type wireless power supply device according to claim 1, characterized in that, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A comparator is provided inside the inverter, an AC current based on the current or magnetic field of the power supply coil detected by the sensor is input to the comparator, and a phase synchronization circuit PLL as the phase adjustment circuit is provided after the output of the comparator, The inverter controls the phase relationship by advancing or retarding the phase of the AC voltage applied to the power supply side resonance circuit with respect to the AC current in the power supply coil through the phase synchronization circuit PLL.

6. The magnetic resonance type wireless power supply device according to claim 5, wherein The phase synchronization circuit PLL has at least a voltage controlled oscillator VCO, and the frequency range of the output signal of the phase synchronization circuit PLL is limited by limiting the oscillation frequency of the voltage controlled oscillator VCO by controlling the input voltage of the voltage controlled oscillator VCO.

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