Ac signal transmission device and ac device

Abstract

To maintain high efficiency even when the positional relationship between resonators constituting a resonator pair changes in a device that transmits AC power by utilizing resonance between resonators.SOLUTION: An AC signal transmission device includes a transmission line, a plurality of first phase-shift circuits connected to the transmission line at a branch point, a plurality of resonator pairs including a transmitting coil and a receiving coil connected to each of the plurality of first phase-shift circuits, and a plurality of second phase-shift circuits respectively connected to the plurality of resonator pairs. The plurality of second phase-shift circuits are connected at a junction point.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to an AC signal transmission device and an AC device. [Background technology]

[0002] With the spread of electric vehicles and portable devices, there is an increasing demand for contactless power supply devices that transmit AC power contactlessly.

[0003] Various methods have been proposed for non-contact power supply, but power transmission using magnetic resonance, which is lighter and has a longer transmission distance than the electromagnetic induction method, has attracted attention (for example, Non-Patent Document 1). The non-contact power supply method described in Non-Patent Document 1 supplies power by magnetic resonance between resonators, so the distance between coils and the accuracy of positioning are relaxed. In addition, the device does not use magnetic materials, so the device is lightweight.

[0004] By increasing the Q value of the coil used in the contactless power supply device, it is possible to transmit power highly efficiently even with a low coupling coefficient (for example, Non-Patent Document 2). In the contactless power supply method of Non-Patent Document 2, the transmission characteristics change significantly when the coupling coefficient k changes due to a change in the distance between the resonators, and therefore adjustments are required in response to changes in the transmission characteristics.

[0005] According to microwave filter theory, reflection-free transmission is possible by setting the external Q of the resonator in accordance with the coupling coefficient k (for example, Non-Patent Document 3).

[0006] The external Q can be set by dividing a capacitor used in a resonator and adjusting the capacitance value of each divided capacitor (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 7039087 [Patent Document 2] Patent No. 6729919 [Patent Document 3] Patent No. 4835334 [Patent Document 4] Patent No. 7261517 [Non-patent literature]

[0008] [Non-Patent Document 1] Wireless Power Transfer via Strongly Coupled Magnetic Resonances, Andre Kurs et.al, Science Vol.317, July 6, 2007 [Non-Patent Document 2] T.Ohira “Angular expression of maximum power transfer efficiency in reciprocal two-port systems” Published in 2014 IEEE Wireless Power Transfer Conference, May 8-9 2014, INSPEC Accession Number: 14395324 [Non-Patent Document 3] I.Awai and T.Ishizaki “Superiority of BPF theory for design of coupled resonator WPT systems” Asia-Pacific Microwave Conference 2011, pp.1889-1892 (2011) INSPEC Accession Number: 12656013 [Non-Patent Document 4] SYRHui, W.Zhong and CKLee “A Critical Review of Recent Progress in Mid-Range Wireless Power Transfer” IEEE Transactions on Power Electronics, vol.29, no.9, pp.4500-4511, Sept. 2014 [Non-Patent Document 5] Takehiro Imura, "Wireless Power Transmission by Magnetic Resonance", Morikita Publishing, 2017, p.326-328 Summary of the Invention [Problem to be solved by the invention]

[0009] In a non-contact power transfer system that supplies power by magnetic resonance between resonators, if the coupling coefficient k is changed by changing the distance between the resonators, the transmission characteristics change significantly. Therefore, it is necessary to change the external Q value by changing the impedance of the power source or load connected to the resonator and the value of the capacitor in response to the change in the coupling coefficient k. In many non-contact power transfer systems, it is unavoidable that the positional relationship between the power transmitting coil and the power receiving coil changes. In other words, the coupling coefficient k is not constant each time power is transferred, and the transmission characteristics change, so it is necessary to change the circuit parameters such as the capacitance value.

[0010] Changing the circuit parameters requires replacing or switching parts, which complicates the mechanism and requires additional control. Therefore, methods have been proposed that use mechanical methods to return the coupling coefficient k to its original state when the positional relationship changes (for example, Patent Document 2). However, the method in Patent Document 2 requires mechanical operations and cannot respond instantly.

[0011] It is therefore desirable to maintain high efficiency even if the positional relationship between the resonators constituting a resonator pair changes.

[0012] An object of the present invention is to provide a power transfer system and device capable of maintaining high efficiency even if the positional relationship between resonators constituting a resonator pair changes. [Means for solving the problem]

[0013] An AC signal transmission device in one embodiment of the present disclosure includes a transmission line, a plurality of first phase-shift circuits connected to the transmission line at a branch point, a plurality of resonator pairs connected to each of the plurality of first phase-shift circuits, and a plurality of second phase-shift circuits connected to each of the plurality of resonator pairs, and the plurality of second phase-shift circuits are connected at a junction point. Effect of the Invention

[0014] The AC signal transmission device and the AC device according to the present disclosure enable highly efficient power transmission even if the positional relationship between the resonators changes. [Brief description of the drawings]

[0015] [Figure 1] Diagram showing a series resonant circuit [Diagram 2] Diagram showing a parallel resonant circuit [Diagram 3] Schematic diagram of a resonant power transmission circuit [Figure 4] Diagram showing SS type resonant power transmission circuit [Diagram 5] A diagram showing the reflection and transmission characteristics of the SS-type resonant power transmission circuit [Figure 6] The complex reflectance and transmittance of the SS-type resonant power transmission circuit shown on the Smith chart. [Figure 7] Circuit diagram of a wireless power transmission device using multiple resonator pairs [Figure 8] FIG. 1 shows the arrangement of resonator coils in a multi-resonator configuration. [Figure 9] A Smith chart showing the reflectance in a dual-cavity configuration. [Figure 10] This figure shows the transmittance and reflectance when a multi-cavity circuit is used, which uses two single-cavity circuits with maximum flatness matching at k=0.1. [Figure 11] A diagram showing the transmission and reflection characteristics when the phase shift angle on the power receiving side is changed while the phase shift angle on the power transmitting side is fixed at 20°. [Figure 12] A diagram showing the reflection and transmission characteristics of four different circuit configurations. [Figure 13A]A diagram showing a circuit using a SS type resonant power transmission circuit with a resistor connected to a zero ohm power supply. [Figure 13B] A diagram showing a circuit using a SS type resonant power transmission circuit with a capacitor connected to a zero-ohm power supply. [Figure 13C] A diagram showing a circuit using a SS type resonant power transmission circuit with an inductor connected to a zero-ohm power supply. [Figure 13D] A diagram showing a circuit using an SS type resonant power transmission circuit with an impedance line connected to a zero-ohm power supply. [Figure 14] A diagram showing the output power of a power supply and the power consumption of a load when using an SS-type resonant power transmission circuit. [Figure 15] A diagram showing the output power of a power supply and the power consumption of a load when using an SP type resonant power transmission circuit. [Figure 16] A diagram showing the output power of the power supply and the power consumption of the load when a PS-type resonant power transmission circuit is used. [Figure 17] A diagram showing the output power of a power supply and the power consumption of a load when a PP-type resonant power transmission circuit is used. [Figure 18] A diagram showing an example of a phase shift circuit using an LC circuit [Figure 19] FIG. 1 shows an example of a multi-resonator configuration using an open-ring resonator. [Figure 20] A diagram showing the transmittance and reflectance when transmitting using an open ring resonator. [Figure 21] A diagram showing the effect of the feed-side line length on the transmission power of a single resonator configuration. [Figure 22] A diagram showing the effect of the feed-side line length on the transmission power of a multi-resonator configuration. [Figure 23] A diagram showing the reflection and transmission characteristics of a multi-line configuration DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] 1 is a diagram showing a series resonant circuit in which a load or power source 110 is connected to a capacitor 120 and a coil 130 in series.

[0017] 2 is a diagram showing a parallel resonant circuit in which a load or power source 210 is connected to a capacitor 220 and a coil 230 in parallel.

[0018] 3 is a schematic diagram of a resonant power transmitting circuit. The resonant power transmitting circuit includes an AC power supply (power supply) 310, a power transmitting side resonator capacitor 320, a power transmitting side resonator coil (power transmitting coil) 330, a power receiving side resonator coil (power receiving coil) 340, a power receiving side resonator capacitor 350, and a load 360.

[0019] In Fig. 3, the power transmitting side resonator capacitor 320 and the power transmitting side resonator coil 330 are connected in series, so the power transmitting side circuit is called a series connection type (Series type, S type). Also, the power receiving side resonator capacitor 350 and the power receiving side resonator coil 340 are connected in series, so the power receiving side circuit is also S type. A resonant power transmitting circuit in which the power transmitting side circuit is S type and the power receiving side circuit is S type is called an SS type resonant power transmitting circuit.

[0020] Since power transmission is possible if there is electromagnetic coupling between the coils, power transmission is also possible using parallel-connected resonators in addition to series-connected resonators.

[0021] In other words, in addition to SS type resonant power transmitting circuits, SP type resonant power transmitting circuits in which the transmitting side circuit is S type and the receiving side circuit is a parallel connection type (parallel type, P type), PS type resonant power transmitting circuits in which the transmitting side circuit is P type and the receiving side circuit is S type, and PP type resonant power transmitting circuits in which the transmitting side circuit is P type and the receiving side circuit is P type may also be used for power transmission.

[0022] In general, the resonant frequency f0 of a resonator is expressed as follows, where L0 is the inductance of the coil and C0 is the capacitance of the capacitor:

number

number

[0023] Here, the characteristic impedance of the signal line connected to the resonator, and the external circuit such as the power supply or load connected to the signal line is Z S Then, Q, which is an external Q, e is defined as follows:

number

[0024] According to Non-Patent Document 3, the coupling coefficient k and the external Q of the power transmitting resonator Q eT , and Q, which is the external Q of the receiving resonator eR If the relationship shown in the following formula is satisfied, power can be transmitted without reflection between the transmitting and receiving resonators. This is called "median matching".

number

[0025] Furthermore, according to Non-Patent Document 3, when the relationship shown in the following formula is satisfied, a "flattest matching" is achieved in which the highly efficient frequency range extends over the entire range between the resonant frequencies.

number

[0026] In wireless power transmission, the transmission signal usually uses a single frequency, so there is no need for high efficiency over a wide bandwidth. Since it is only necessary to optimize the case where the resonant frequency of the resonator is used, it is sufficient that the condition of equation (4), which has a looser condition, is satisfied.

[0027] However, according to Non-Patent Document 3, for the same coupling coefficient k, if the maximally flat matching of equation (5) is satisfied, the loss due to the internal resistance of the coil can be minimized. In addition, since the maximally flat matching has a wider frequency band where the efficiency is high, there is an advantage that there is a margin for circuit errors that occur when creating the resonator and the peripheral circuits.

[0028] Therefore, it is effective to use conditions as close as possible to those of equation (5). In the following explanation, we will explain the conditions under which the maximally flat matching of equation (5) is established, but as mentioned above, in wireless power transmission, the conditions of equation (4) may be satisfied.

[0029] Combining equations (3a) or (3b) and (4), the reflection-free coupling is given by the following equation for each resonant transmitting circuit type, where Z ST is the output impedance of the power source on the transmitting side, Z SR is the input impedance of the receiving load, Z KT is the resonator impedance of the power transmitting resonator, Z KR is the resonator impedance of the power receiving side resonator.

number

[0030] These equations are expressed as the output impedance Z of the transmitting power source when non-reflective coupling is used. ST When the resonator coupling is applied, the input impedance of the receiving load is Z SR This shows that the resonant power transmission circuit functions as an impedance converter that changes depending on the coupling coefficient k.

[0031] In the following, an SS type resonant power transmitting circuit will be described as an example, but the same applies to other types as well if the impedance conversion according to any one of the formulas (6b) to (6d) corresponding to the type is used.

[0032] 4 is a diagram showing an SS type resonant power transmitting circuit. Here, when the resonator is configured with a power transmitting coil 413 and a power receiving coil 423, both of which are 1.591 μH, and a capacitor 412 and a capacitor 422, both of which are 159.1 pF, the resonant frequency of the resonator is 10 MHz, and the characteristic impedance Z K is 100 Ω. Power transmitting coil 413 and power receiving coil 423 of 1.591 μH can be configured with one turn of wire with a diameter of about 40 cm.

[0033] Coupling coefficient k is about 0.05 when the distance between power transmitting coil 413 and power receiving coil 423 is approximately the same as the diameter. Coupling coefficient k decreases inversely proportional to the cube of the distance. The range of coupling coefficient k is determined depending on the application, but in this embodiment, it is assumed to be about 0.01 to 0.5.

[0034] The output impedance of the line connected to the terminal 410 of the power transmitting resonator, for example, the power supply, is Z T The input impedance of the line connected to the terminal 420 of the receiving resonator is Z R Here, Z T = 10Ω, Z R = 10Ω, the characteristic impedance of the resonator Z K Since is 100Ω, according to equation (3a), the external Q on the power transmission side, Q eT is 10, and the external Q of the receiving side is Q eR is also 10. Therefore, when k = 0.1, equation (5) holds, and the flattest matching can be achieved.

[0035] Fig. 5 is a diagram showing the reflection and transmission characteristics of the SS-type resonant power transmitting circuit when the coupling coefficient k is changed for a 10 MHz signal. In Fig. 5, the dotted line shows the reflection characteristics (reflectance) and the solid line shows the transmission characteristics (transmittance).

[0036] Figure 6 shows the complex reflectance and transmittance of the SS-type resonant power transmission circuit on a Smith chart. In Figure 6, the reflectance of the SS-type resonant power transmission circuit is shown by white circles and black circles, and the transmittance is shown by white diamonds and black diamonds.

[0037] As the coupling coefficient k changes, the reflectivity of the SS-type resonant power transmission circuit moves from -1 to 1 on the real axis, passing through the origin where reflection is zero at k = 0.1. On the other hand, the transmittance lags by 270°, that is, moves through the positive region on the imaginary axis, moves upward from near the origin, reaches the outer periphery and turns back at k = 0.1.

[0038] As described above, either series or parallel resonators can be used for the resonators on the transmitting and receiving sides. As shown in equations (6a) to (6d), when the resonator impedance and coupling coefficient are determined, the combination of the optimal source impedance and optimal load impedance that eliminates reflection changes depending on the combination of resonator types. By applying a resonator type that has values ​​close to the impedance of the power supply and the resistance of the load that are actually used, a circuit with low loss can be configured.

[0039] Therefore, in addition to the SS type resonant power transmission circuit, we also consider the SP type, PS type, and PP type resonant power transmission circuits.

[0040] The coupling coefficient k is determined by the distance between the coils that make up the resonator, so it does not change whether a series resonator or a parallel resonator is used. Also, the resonator impedance will be the same if the resonant frequency and coil are the same. To achieve maximal flatness matching, it is necessary to satisfy (5). For example, when k=0.1, the Q eT =10.

[0041] Characteristic impedance Z of the resonator K When a series resonator is used, the characteristic impedance Z of the signal source is calculated from equation (3a) as follows: T When a parallel resonator is used, the characteristic impedance Z of the signal source is calculated from equation (3b). T By setting the impedance to 1000Ω, power can be transmitted while satisfying the flattest matching. The same is true for the load impedance on the receiving side.

[0042] Regardless of the corresponding counterpart, if the resonator is a series type, when k is small, the reflectivity is near -1 on the real axis of the Smith chart, and as k becomes larger, it passes through the origin at k = 0.1 and moves toward +1. If the resonator is a parallel type, when k is small, the reflectivity is +1, and as k becomes larger, it passes through the origin at k = 0.1 and moves toward -1.

[0043] Regarding transmittance, with the SS type, as shown in Figure 6, the phase lag is always 270 degrees (positive direction on the imaginary axis), and when k is small it is near the origin, and when k = 0.1 it is on the outer periphery of transmittance 1, and when it is greater than that it returns to the origin. The SP and SS types have a phase lag of 0 degrees (positive direction on the real axis) and show similar changes. The PP type has a phase lag of 90 degrees (negative direction on the imaginary axis) and shows similar changes.

[0044] When phase is included, the changes are as shown above, but the absolute values ​​of reflectance and transmittance are almost the same as those of the SS type in Figure 5 for all formats.

[0045] (Multi-resonator configuration) Fig. 7 is a circuit diagram of a wireless power transmission device using multiple resonator pairs. Two SS-type resonant power transmission circuits are connected in parallel, and a phase-shift circuit is installed before and after each resonant power transmission circuit. Hereinafter, the configuration in which two resonator circuits are connected in parallel as shown in Fig. 7 is referred to as a multi-resonator configuration, and the configuration with one resonator circuit as shown in Fig. 3 is referred to as a single-resonator configuration.

[0046] In Fig. 7, a plurality of lines connected in parallel to an input terminal 701 are connected at a branch point 702. A line means a series of circuits connected in series. For convenience, the upper line in Fig. 7 is called line 1 and the lower line is called line 2. The capacitance C A 1. The capacitance C of the capacitor 722 B 1. Capacitance C of capacitor 732 A 2. Capacitance C of capacitor 742 B 2 are equal, and the inductance L A 1. Inductance L of the receiving coil 723 B 1. Inductance L of the transmitting coil 733 A 2. Inductance L of the receiving coil 743 B 2 is also equal.

[0047] An input terminal 701 is connected to a branch point 702. The branch point 702 branches into a line 1 and a line 2. The line 1 has a phase shift circuit 711, a resonator pair, and a phase shift circuit 721. The resonator pair has a capacitor 712, a power transmitting coil 713, a power receiving coil 723, and a capacitor 722.

[0048] One end of the phase shift circuit 711 is connected to the branch point 702. The other end of the phase shift circuit 711 is connected to one end of a capacitor 712. The other end of the capacitor 712 is connected to one end of a power transmitting coil 713. The other end of the power transmitting coil 713 is grounded (connected to ground). The power transmitting coil 713 and the power receiving coil 723 are coupled with a coupling coefficient k1.

[0049] One end of the receiving coil 723 is grounded. The other end of the receiving coil 723 is connected to one end of a capacitor 722. The other end of the capacitor 722 is connected to one end of a phase shift circuit 721. The other end of the phase shift circuit 721 is connected to a branch point (junction point) 752. The branch point 752 is connected to an output terminal 751.

[0050] The line 2 includes a phase shift circuit 731, a resonator pair, and a phase shift circuit 741. The resonator pair includes a capacitor 732, a power transmitting coil 733, a power receiving coil 743, and a capacitor 742.

[0051] One end of the phase shift circuit 731 is connected to the branch point 702. The other end of the phase shift circuit 731 is connected to one end of a capacitor 732. The other end of the capacitor 732 is connected to one end of a power transmitting coil 733. The other end of the power transmitting coil 733 is grounded (connected to ground). The power transmitting coil 733 and the power receiving coil 743 are coupled with a coupling coefficient k2.

[0052] One end of the power receiving coil 743 is grounded. The other end of the power receiving coil 743 is connected to one end of the capacitor 742. The other end of the capacitor 742 is connected to one end of the phase shift circuit 741. The other end of the phase shift circuit 741 is connected to the branch point 752.

[0053] Each phase shift circuit has input and output symmetry, and the input impedance and output impedance are the same. Therefore, the phase shift circuit is a circuit that generates the same phase delay for signals input from either side.

[0054] (Configuration of a coil with a multi-resonator configuration) In a resonant power transmission device, when the positional relationship between the transmitting and receiving coils is changed, the electrical effect appears as a change in the coupling coefficient. That is, the coupling coefficient changes depending on the distance between the transmitting coil and the receiving coil, and the relative orientation of the transmitting coil and the receiving coil. In a multi-resonator configuration, it is possible to make the two coupling coefficients change by the same value by devising the coil arrangement.

[0055] Fig. 8 is a diagram showing the arrangement of resonator coils in the multi-resonator configuration of Fig. 7. A power transmitting coil 713 and a power transmitting coil 733 are arranged on a power transmitting side substrate 810. A power receiving coil 723 and a power receiving coil 743 are arranged on a power receiving side substrate 820. The power transmitting coil 713, the power transmitting coil 733, the power receiving coil 723, and the power receiving coil 743 have the same configuration and the same characteristics.

[0056] The transmitting coil 713 and the receiving coil 723 are coils of the resonator of the line 1, and the transmitting coil 733 and the receiving coil 743 are coils of the resonator of the line 2. The boards 810 and 820 are arranged in parallel, and when they are arranged in a reference position, the transmitting coil 713 and the receiving coil 723 are arranged opposite each other, and the transmitting coil 733 and the receiving coil 743 are arranged opposite each other.

[0057] Assuming that power is transmitted from the ground side to the vehicle side, the ground side, i.e., the power transmission side, is fixed, so the substrate 810 is fixed, and the vehicle side, i.e., the entire power receiving side, is movable. When a car is parked on a flat road surface, the substrates 810 and 820 are parallel, but depending on the parking position and orientation of the car and the difference between cars, the substrate 820 may move in parallel in the x and y directions relative to a reference position depending on the parking position of the car, and may rotate on an axis perpendicular to the substrate depending on the direction in which the car is parked. However, if the parking direction of the car is kept constant, the substrate 820 moves in parallel in the x, y, and z directions while keeping its orientation fixed, compared to when it is placed exactly opposite, but no rotation occurs.

[0058] Since the transmitting coil 713 and the transmitting coil 733 are arranged on the substrate 810, and the receiving coil 723 and the receiving coil 743 are arranged on the substrate 820, with respect to movement in the x, y, and z directions while the orientation of the substrates 810 and 820 is fixed, the distance between the transmitting coil 713 and the receiving coil 723 is the same as the distance between the transmitting coil 733 and the receiving coil 743.

[0059] That is, the coupling coefficient k1 between the power transmitting coil 713 and the power receiving coil 723 and the coupling coefficient k2 between the power transmitting coil 733 and the power receiving coil 743 are the same value (k1=k2) although they change. That is, even if the position where the vehicle stops shifts forward, backward, left or right and the coupling state changes, the coupling coefficient of the two resonator pairs will always be the same value as long as the orientation of the vehicle is kept constant.

[0060] Furthermore, if the vehicle height changes due to the weight of the vehicle body and the coupling state changes, the distance in the z direction between substrates 810 and 820 changes, but the distance between transmitting coil 713 and receiving coil 723 and the distance between transmitting coil 733 and receiving coil 743 remain the same, and the coupling coefficient changes but the value remains the same.

[0061] Furthermore, substrates 810 and 820 may rotate about a common rotation axis 830, changing the coupling state. If the rotation axis is positioned at a point equidistant from the two coils, the distance between power transmitting coil 713 and power receiving coil 723 and the distance between power transmitting coil 733 and power receiving coil 743 are the same even when substrates 810 and 820 rotate about rotation axis 830. In other words, the coupling coefficient k1 between power transmitting coil 713 and power receiving coil 723 and the coupling coefficient k2 between power transmitting coil 733 and power receiving coil 743 are the same value (k1=k2) although they change.

[0062] Thus, in the resonator coupling circuit of FIG. 7, the inductance of each coil is the same, the capacitance is the same, and the coupling coefficient of each resonator changes but the value is the same.

[0063] By using mechanical links and cam mechanisms, this relationship can be realized even in more complex multi-resonator configurations.

[0064] The way in which the coupling coefficient between coils changes varies depending on the shape of the coils. Therefore, if the shapes of the coils are not the same, the design becomes complicated, so it is desirable that the shapes of the coils are the same.

[0065] If the characteristic impedance of each line between the branch point 702 and the branch point 752 in FIG. 7 is 10Ω, the input impedance Z T0 , the output impedance Z at the output terminal 751 that is matched at the branch point 752 R0 Both are 5 Ω, half the characteristic impedance of each line. To avoid confusion, below, the line impedance will be expressed as the value for each single line in the multi-line state. In other words, unless otherwise specified, the characteristic impedance before one line branches into two lines, or after two lines are combined into one line, is half the line impedance. This ensures impedance matching at branch points 702 and 752.

[0066] Fig. 9 shows the reflectance in a multi-resonator configuration on a Smith chart. Here, the reference impedance is 10Ω. In the circuit of Fig. 7 described above, when the phase angles of the four phase shift circuits are all 0°, it is the same as when there are no phase shift circuits, and is therefore equivalent to two circuits of Fig. 4 connected in parallel. In other words, the k-value dependency of the reflectance as viewed from the branch point 702 on both the line 1 side and the line 2 side is the same as in Figs. 5 and 6.

[0067] When k=0.1, the reflectance is zero, so the reflectance is at the origin 901. In other words, a signal is transmitted from input terminal 701 to output terminal 751 through both line 1 and line 2 without reflection.

[0068] Next, a case where k=0.013 due to a change in the positional relationship of the resonators will be described.

[0069] Fig. 7 shows the SS-type resonant power transmission circuit with a series resonator on both the transmitting and receiving sides. The characteristic impedance of the resonator is Z K is 100Ω, so considering equations (3a) and (5), the output impedance Z of the power source on the transmitting side is ST and the input impedance Z of the receiving load SR Both are 1.3Ω (Z TO ,Z SO The flattest match is achieved when the vertices are aligned (half of the vertices).

[0070] If the power receiving side has an input impedance of the power receiving load, Z SR If is set to 1.3 Ω where the flattest matching is achieved, and the output impedance of the power supply on the power transmitting side remains at 10 Ω, the reflectance of the resonator portion as seen from the power transmitting side is (−0.77, 0), that is, point 902 in FIG.

[0071] Here, the phase shift angle of the phase shift circuit 711 is changed. If the characteristic impedance of the phase shift circuit is set to 10 Ω, the same as the reference impedance, the reflection coefficient moves on a circumference 910 centered at the origin.

[0072] When the phase angle changes by ±40° on the circumference 910, it intersects with the 10 Ω equal conductance circle 911 at two points, points 903 and 904. The impedances represented by points 903 and 904 both have real parts of 10 Ω, and the imaginary parts have the same absolute value but opposite signs.

[0073] In other words, in the circuit of FIG. 7, if the phase shift angle of phase shift circuit 711 and the phase shift angle of phase shift circuit 731 are adjusted as described above, the real part of the composite impedance of the two lines seen from branch point 702 will be 5 Ω and the imaginary part will be 0. Therefore, even if the line is branched into two lines at branch point 702, impedance matching is established and no reflection will occur at branch point 702.

[0074] In addition, since the delay in the phase shift circuit can only take positive values, changing the phase shift angle by ±X° means performing a phase shift of +X° (arrow 912) and a phase shift of (360-X)° (arrow 913).

[0075] In the case of a reflected wave, since the wave passes through the phase shift circuit twice, the change in the phase angle of the phase shift circuit is +X / 2°, which is half of +X°, and (180-(X / 2))°. That is, in the case of FIG. 7, the phase shift angle of phase shift circuit 711 is Δ°, and the phase shift angle of phase shift circuit 731 is (180-Δ)°, where Δ is 20.

[0076] Here, it is assumed that the impedance of the receiving side line is already 1.3Ω. However, since the impedance at branch point 752 is actually 10Ω, the same method is used as for the transmitting side to make it appear as if a line with a characteristic impedance of 1.3Ω is connected. In other words, the phase shift angle of phase shift circuit 721 is (180-Δ)°, and the phase shift angle of phase shift circuit 741 is Δ°, where Δ is 20. Two phase shift angles are assigned to lines 1 and 2, and they are selected so that the total phase delay between the transmitting side and the receiving side of lines 1 and 2 is the same value.

[0077] Figure 10 shows the transmittance and reflectance when a multi-cavity circuit is used, which uses two single-cavity configurations that are maximally flat-matched at k=0.1. Line 1001 shows the transmittance when Δ=20, line 1003 shows the transmittance when Δ=40, line 1005 shows the transmittance when Δ=60, line 1002 shows the reflectance when Δ=20, line 1004 shows the reflectance when Δ=40, and line 1006 shows the reflectance when Δ=60. In all cases, there is no reflection when k=0.1, but the other k value at which there is no reflection can be set to 0.013, 0.069, and 0.3, respectively.

[0078] In addition, although the phase shift amounts on the transmitting side and the receiving side are the same in FIG. 10, they do not necessarily have to match.

[0079] FIG. 11 is a diagram showing the transmission characteristic and the reflection characteristic when the phase angle of the power transmitting side phase shift circuit is fixed at 20° and the phase angle of the power receiving side phase shift circuit is changed.

[0080] Lines 1001 and 1002 are the same as in Fig. 10 because the receiving side also has Δ=20. Line 1103 shows the transmission characteristics when Δ=40 on the receiving side, line 1105 shows the transmission characteristics when Δ=60 on the receiving side, line 1104 shows the reflection characteristics when Δ=40 on the receiving side, and line 1106 shows the reflection characteristics when Δ=60 on the receiving side.

[0081] For lines 1103 to 1106, there is no peak at k=0.1, which is set by the external Q of the single line, and although reflection exists, impedance matching is achieved at two other k values, and the transmittance also has a peak by setting the reflectance to 0 at two k values.

[0082] When the two k values ​​for impedance matching are significantly different, the transmittance peak is split into two, but by bringing the k values ​​closer together, it is possible to maintain a nearly constant efficiency between the peaks. It is also possible to match the two k values. Even when the two k values ​​are matched, the flatness of the efficiency near the peak increases compared to the single-cavity configuration, and the range of high efficiency increases.

[0083] The above explanation was about the SS type resonant power transmission circuit, but the same applies to the SP type resonant power transmission circuit, the PS type resonant power transmission circuit, and the PP type resonant power transmission circuit. When changing the type, it is necessary to pay attention to the difference between formula (3a) and formula (3b), and the phase delay in the resonator itself.

[0084] Taking these factors into consideration, the signal source impedance and the phase shift angle of the phase shift circuit are shown in Table 1. [Table 1]

[0085] In Table 1, Δ T is the phase shift angle of the phase shift circuit on the power transmission side, Δ R is the phase shift angle of the phase shift circuit on the receiving side, Z K is the resonator impedance, and k0 is the set k value (0.1 in the embodiment). T Comrades and Δ R If the same values ​​are used, almost the same reflection and transmission characteristics can be obtained regardless of the circuit type.

[0086] Fig. 12 is a diagram showing reflection and transmission characteristics in four different circuit configurations. In Fig. 12, the impedance of the power supply or load is set to 1000Ω when a parallel resonator is used, the impedance of the power supply or load is set to 10Ω when a series resonator is used, and the phase shift angle is set to Δ T = 20° and Δ R The transmission and reflection characteristics are shown in Table 1 when the angle is set to 60°.

[0087] Line 1214 shows the transmission characteristics, and almost the same transmission characteristics are shown for all types of SS type resonant power transmitting circuit, SP type resonant power transmitting circuit, PS type resonant power transmitting circuit, and PP type resonant power transmitting circuit. In Fig. 12, line 1106 shows the reflection characteristics of the SS type resonant power transmitting circuit, line 1211 shows the reflection characteristics of the PP type resonant power transmitting circuit, line 1212 shows the reflection characteristics of the PS type resonant power transmitting circuit, and line 1213 shows the reflection characteristics of the SP type resonant power transmitting circuit. Although there are slight differences, almost the same characteristics can be obtained.

[0088] (using a zero ohm power supply) In the explanation so far, in the circuit with the multi-resonator configuration shown in Fig. 7, the output impedance of AC power supply 310 connected to input terminal 701 and the input impedance of load 360 connected to output terminal 751 are finite impedances. This is to eliminate reflections between the power supply and the cable, and between the cable and the load, by making the output impedance of the power supply and the input impedance of the cable the same impedance. It can be said that eliminating reflections is a common practice in microwave circuits.

[0089] However, if the power supply has a finite output impedance, power consumption occurs due to the impedance inside the power supply, and although reflection in the resonator section can be prevented, the power efficiency of the entire system decreases (for example, non-patent document 4).

[0090] To avoid power consumption within the power supply, a switching power supply is used, which is composed of a lossless switch and a lossless filter such as an LC circuit. Since a switching power supply is a voltage source whose output voltage does not change depending on the load, its output impedance is 0 Ω and it is called a zero ohm power supply.

[0091] In this embodiment, power is transmitted, and it is preferable that there is no power consumption inside the power supply, so it is preferable to use a zero ohm power supply. On the other hand, if the output impedance of the power supply is set to 0 ohms, there is no matching between the power supply and the line, and reflections occur.

[0092] Therefore, the effect of using a zero ohm power supply in which impedance matching is not established at the connection point with the power supply will be verified.

[0093] 13A is a diagram showing a circuit in which a resistor is inserted in series with a zero ohm power supply and an SS type resonant power transmission circuit is used in a normal power supply circuit with a finite resistance. The SS type resonant power transmission circuit uses the circuit in FIG.

[0094] When setting the flattest matching at k=0.1, the impedance on the power supply side and the impedance on the load side are 10 ohms. Also, the phase shift angle in the phase shift circuit is expressed as Δ T = 20°, Δ R = 60°.

[0095] The reflection characteristic when using a power supply having a finite output impedance that is matched to the input impedance of the resonator circuit is shown by line 1106 in Figure 12, and the transmission characteristic is shown by line 1214 in Figure 12. By referring to line 1106 showing the reflection characteristic, it can be seen that the reflection is zero at k = 0.035 and k = 0.170.

[0096] Here, assuming power transmission, AC power supply 1310 in FIG. 13A is a zero ohm power supply with an output effective voltage of 100 V, and resistor 1330 is 5 Ω.

[0097] FIG. 14 is a diagram showing the output power of the zero ohm power supply 1310 and the power consumption of the load when the SS type resonant power transmitting circuit is used.

[0098] In this case, as shown in Fig. 12, impedance is matched at k = 0.035 and k = 0.170, and the load seen from the zero ohm power supply 1310 is 10 Ω because it is a series connection of the resistor 1330 and the resonant power transmission circuit 700 having a multiple resonator configuration. Since the output effective voltage of the zero ohm power supply 1310 is 100 V, the supply power is (100 V) 2 / 10Ω = 1000W.

[0099] In Fig. 14, line 1410 shows the power consumed by load 1320 when 5 Ω resistor 1330 is inserted in series with the output of zero ohm power supply 1310, and line 1420 shows the power output by zero ohm power supply 1310 in that case. The difference between these is the power consumed by resistor 1330. This is the power loss in an impedance-matched power supply, and our goal here is to eliminate it.

[0100] At k=0.035 and 0.17 where the reflection becomes zero, of the 1000 W output power of the zero ohm power supply 1310, 500 W is consumed by the resistor 1330 and 500 W is consumed by the load 1320.

[0101] In other words, the loss is 50%, or the efficiency is 50%. An efficiency of 50% is hardly considered highly efficient power transmission.

[0102] In order to reduce the loss due to consumption in the resistor 1330, it is necessary to reduce the resistance value of the resistor 1330 connected in series with the zero ohm power supply 1310. If the resistance value of the resistor 1330 is 0 Ω, no loss occurs due to the resistor 1330.

[0103] When the resistance value of resistor 1330 is reduced, the two k values ​​at which the power output by zero ohm power supply 1310 peaks approach each other, and when the resistance value becomes 0 Ω, they converge to one. The power output by zero ohm power supply 1310 when resistor 1330 becomes 0 Ω is represented by line 1460 in FIG.

[0104] In this case, even if the voltage of zero ohm power supply 1310 is fixed, the power output by zero ohm power supply 1310 varies greatly depending on the k value. In other words, to keep the power supplied to load 1320 constant, the voltage supplied by zero ohm power supply 1310 needs to be changed according to the k value, which creates extra work. In addition, the current value also needs to be changed, which requires adding extra capacity to the power supply.

[0105] Fig. 13B shows a circuit in which a capacitor 1331 is connected instead of the resistor 1330 in Fig. 13A. Fig. 13C shows a circuit in which an inductor 1332 is connected instead of the resistor 1330 in Fig. 13A. Fig. 13D shows a circuit in which an impedance line 1333 is connected instead of the resistor 1330 in Fig. 13A. The capacitor 1331, the inductor 1332, and the impedance line 1333 do not generate loss even when a current flows.

[0106] When connecting the capacitor 1331 or the inductor 1332, set the reactance value, which is the imaginary part of the impedance, to 5 Ω, the same value as the resistance value of the resistor 1330.

[0107] Specifically, when connecting the capacitor 1331 instead of the resistor 1330, connect a 3.183 nF capacitor. When connecting the inductor 1332 instead of the resistor 1330, connect a 79.6 nH inductor.

[0108] Also, when connecting the impedance line 1333 instead of the resistor 1330, connect an impedance line with a characteristic impedance of 5 Ω and a line length of 1 / 8 of the wavelength (phase shift angle of 45°). By these means, the k value at which the reflection becomes zero is the same as when the resistor 1330 in Fig. 13A is set to 5 Ω.

[0109] In Fig. 14, line 1430 indicates the power consumed by the load 1320 in Fig. 13B, line 1440 indicates the power consumed by the load 1320 in Fig. 13C, and both show exactly the same characteristics. In Fig. 14, line 1450 indicates the power consumed by the load 1320 in Fig. 13D.

[0110] For lines 1430, 1440, and 1450, the peaks of the power consumption are at k = 0.035 and k = 0.17, and the peak power is 1000 W for lines 1430 and 1440, and 2000 W for line 1450.

[0111] Although the peak power values are different, in all cases, the peaks of the power consumption of the load 1320 are at k = 0.035 and k = 0.17, and for k where 0.035 < k < 0.17, the power consumed by the load 1320 does not change significantly even if the k value varies. In these cases, since the power consumed by the load and the output power of the power source are the same, as the zero-ohm power source 1310, it is not necessary to generate a wide range of power.

[0112] As described above, the case of using the S-S type resonance power transmission circuit has been explained, but the same applies to the S-P type resonance power transmission circuit, the P-S type resonance power transmission circuit, and the P-P type resonance power transmission circuit.

[0113] First, similarly to the SS type resonant power transmitting circuit, the load impedance is set so as to obtain the flattest matching at k = 0.1 for both types of resonant power transmitting circuits. The impedance to be set is 10 Ω for a PS type resonant power transmitting circuit with an S type load-side resonator, and 1000 Ω for an SP type resonant power transmitting circuit or a PP type resonant power transmitting circuit with a P type load-side resonator. 13A, 13B, 13C, and 13D, the resonant power transmitting circuit 700 is of the SS type, but the following description will be given assuming that this portion is appropriately changed to a resonant power transmitting circuit of a corresponding type.

[0114] In the case of an SP type resonant power transmitting circuit, the resistor 1330 connected in series to the zero ohm power supply 1310 to match the impedance between the power supply and the resonant power transmitting circuit is 5 Ω, so the capacitor 1331, inductor 1332, or impedance line 1333 can be of the same capacitance, inductance, or impedance line as the SS type resonant power transmitting circuit.

[0115] On the other hand, in the case of a PS type resonant power transmitting circuit or a PP type resonant power transmitting circuit, the resistance value of resistor 1330 connected in series to zero ohm power supply 1310 for matching is 500Ω, so that the capacitance of capacitor 1331 is 31.83 pF, the inductance of inductor 1332 is 7960 nH, the characteristic impedance of impedance line 1333 is 500Ω, and the line length is 1 / 8 the wavelength (phase shift angle is 45°).

[0116] FIG. 15 is a diagram showing the output power of a power source and the power consumption of a load when an SP type resonant power transmitting circuit is used.

[0117] 15, line 1510 is the power consumed by load 1320 when a 5 Ω resistor 1330 is inserted in series with the output of zero ohm power supply 1310 to match the impedance in the power supply section, and line 1520 is the power output by the power supply in that case. The difference is the power consumed by resistor 1330. Line 1560 is the power consumed by load 1320 when the resistance value of resistor 1330 is 0 Ω.

[0118] Line 1530 is the power consumed by load 1320 of FIG. 13B when resistor 1330 is replaced by capacitor 1331. Line 1540 is the power consumed by load 1320 of FIG. 13C when resistor 1330 is replaced by inductor 1332. Line 1550 is the power consumed by load 1320 of FIG. 13D when resistor 1330 is replaced by impedance line 1333.

[0119] FIG. 16 is a diagram showing the output power of a power source and the power consumption of a load when a PS type resonant power transmitting circuit is used.

[0120] 16, line 1610 is the power consumed by the load when a 500 Ω resistor 1330 is inserted in series with the output of zero ohm power supply 1310 to match the impedance of the power supply, and line 1620 is the power output by the power supply in this case. Line 1660 is the power consumed by load 1320 when the resistance value of resistor 1330 becomes 0 Ω.

[0121] Line 1630 is the power consumed by load 1320 of FIG. 13B when resistor 1330 is replaced by capacitor 1331. Line 1640 is the power consumed by load 1320 of FIG. 13C when resistor 1330 is replaced by inductor 1332. Line 1650 is the power consumed by load 1320 of FIG. 13D when resistor 1330 is replaced by impedance line 1333.

[0122] FIG. 17 is a diagram showing the output power of a power source and the power consumption of a load when a PP type resonant power transmitting circuit is used.

[0123] 17, line 1710 is the power consumed by the load when a 500 Ω resistor 1330 is inserted in series with the output of zero ohm power supply 1310 to match the impedance of the power supply, and line 1720 is the power output by the power supply in this case. Line 1760 is the power consumed by load 1320 when the resistance value of resistor 1330 becomes 0 Ω.

[0124] Line 1730 is the power consumed by load 1320 of FIG. 13B when resistor 1330 is replaced by capacitor 1331. Line 1740 is the power consumed by load 1320 of FIG. 13C when resistor 1330 is replaced by inductor 1332. Line 1750 is the power consumed by load 1320 of FIG. 13D when resistor 1330 is replaced by impedance line 1333.

[0125] 15 to 17, the SP-type resonant power transmission circuit has almost the same output power as the SS-type resonant power transmission circuit, while the PS-type resonant power transmission circuit and the PP-type resonant power transmission circuit have about 1 / 100 of the output power of the SS-type resonant power transmission circuit. This is because the input impedance to the resonator is set to 5Ω for the S-type and 500Ω for the P-type in order to match the external Q to the k value. On the other hand, the increase and decrease with respect to the change in the k value all have peaks at k=0.035 and k=0.17, and there is little fluctuation between them. When a specified capacitor is installed in the power supply section, when a specified inductor is installed, or when a specified impedance line is installed, there is no loss due to the power supply resistance, so all the power supplied from the power supply is consumed by the load, and it can be seen that the power fluctuation due to the change in the k value is suppressed.

[0126] According to Figs. 15 to 17, similarly to the SS type, by placing suitable lossless components, it is possible to transmit a substantially constant power without loss even when the coupling coefficient changes.

[0127] (LC phase shift circuit) In the explanation so far, for the convenience of simulation, the phase shift circuit has been analyzed using an impedance line. However, when using the MHz band, the impedance line becomes physically very long, so it is common to configure the phase shift circuit with individual components such as capacitors and inductors.

[0128] FIG. 18 is a diagram illustrating an example of a phase shift circuit using an LC circuit.

[0129] Table 2 shows the capacitance value C and inductance value L used in the phase shift circuit of Fig. 13 when performing a phase shift of 10° to 90° for a 10 MHz signal with a characteristic impedance of 10Ω or 1000Ω. Phase shifts of 90° or more can be achieved by using multiple stages of this circuit. [Table 2]

[0130] (In the case of an open ring resonator) In the explanation so far, an LC resonator is used as the resonator, and power is transmitted by using electromagnetic coupling due to mutual inductance between coils. However, as the frequency becomes higher, it becomes difficult to use an LC resonator, so an open ring resonator is used instead (for example, Patent Document 3).

[0131] An open ring resonator is a half-wavelength antenna bent into a ring shape with both ends close to each other. By arranging the open ring resonators close to each other, non-contact power transmission is achieved through electromagnetic coupling. The external Q of an open ring resonator is determined by the characteristic impedance of the line itself, the characteristic impedance of the input / output signal line, and the position on the ring to which the signal line is connected (Patent Document 4). The coupling coefficient is determined by the positional relationship between the two open ring resonators, the distance, the relative orientation of the notches, etc.

[0132] 19 is a diagram showing an example of a composite resonator configuration using an open ring resonator. An open ring resonator 1911 and an open ring resonator 1912 are formed on one printed circuit board, and an open ring resonator 1921 and an open ring resonator 1922 are formed on another printed circuit board. The open ring resonators 1911 and 1921, and the open ring resonators 1912 and 1922 are disposed closely facing each other, and output power input from an input line 1913 to an output line 1923 in a non-contact manner.

[0133] In FIG. 19, the metal patterns on each surface are shifted for ease of understanding, but the open ring resonators 1911 and 1921, and the open ring resonators 1912 and 1922 are arranged so as to overlap one another vertically. As a result, even if the substrates on which the open-ring resonators are mounted move apart while remaining parallel, or are shifted laterally, the relative positional relationships between the open-ring resonators 1911 and 1921, and between 1912 and 1922 remain the same, so the coupling coefficients of both resonator sets are equal.

[0134] All of the open-ring resonators use gold wiring 1 μm thick, have an outer diameter of 15 mm, a circumferential line width of 5 mm, and a resonant frequency of 2.45 GHz, and are formed on a printed circuit board 1 mm thick and with a relative dielectric constant of 4.2. Microstrip lines 1914, 1915, 1924, and 1925 with a characteristic impedance of 100 Ω are connected to each open-ring resonator at a location 90° from the midpoint of the ring.

[0135] A phase shift circuit is formed by a microstrip line 1914 and a microstrip line 1915 from the input line 1913 to each open ring resonator mounting portion, and a microstrip line 1924 and a microstrip line 1925 from each open ring mounting portion to an output line 1923. The input line 1913 and the output line 1923 have a characteristic impedance of 50Ω.

[0136] Hereinafter, a configuration in which two resonator pairs are connected in parallel will be referred to as a multi-resonator configuration, and a configuration using one resonator pair will be referred to as a single-resonator configuration, as shown in Fig. 19. The characteristic impedance of the input / output lines of the single-resonator configuration is set to 100Ω, but since two resonator pairs are connected in parallel to the input line 1913 and the output line 1923 of the multi-resonator configuration, matching is achieved by setting the characteristic impedance of the input line 1913 and the output line 1923 to 50Ω.

[0137] When the distance between the printed circuit boards on which the open-ring resonators are configured, i.e., the distance between the open-ring resonators, is changed, the coupling coefficient between the rings decreases as the distance between the open-ring resonators increases. On the other hand, the wiring connection to the open-ring resonator is fixed at 90° from the midpoint of the ring circumference, so the value of the external Q is fixed.

[0138] FIG. 20 is a diagram showing the transmittance and reflectance when light is transmitted using the above-mentioned open ring resonator.

[0139] The transmittance of the single resonator configuration is shown by line 2001, and the reflectance by line 2002. When the ring distance is 4.5 mm, the flattest matching is achieved, the reflectance becomes zero, and the transmittance is at its maximum. Due to losses caused by the skin effect of the gold wiring of the open-ring resonator, the transmittance does not become 1. In the case of the single resonator configuration, the transmittance is 90% or more when the ring distance is in the range of about 1.5 mm, from 3.5 mm to 5 mm.

[0140] On the other hand, in the multi-resonator configuration (Figure 19), line 2003 shows the transmittance and line 2004 shows the reflectance when the phase shift angle of microstrip lines 1915 and 1925 is 55° and the phase shift angle of microstrip lines 1914 and 1924 is 125°.

[0141] In addition to the gap spacing of 4.5 mm, which is the same as the single resonator configuration, reflection is suppressed at the gap spacing of 2.2 mm, achieving a transmittance of 90% within a 5.5 mm range of inter-ring distances from 1 mm to 6.5 mm.

[0142] Line 2005 shows the transmittance and line 2006 shows the reflectance when the phase angles of microstrip line 1914 and microstrip line 1915 on the transmitting side remain the same, and the phase angle of microstrip line 1925 on the receiving side is 35° and the phase angle of microstrip line 1924 is 145°.

[0143] 13A to 13D, the inter-ring distance at which reflection becomes zero is set to two distances different from the set distance of 4.5 mm for the flattest matching in a single line. On the transmitting side and the receiving side, two inter-ring distances at which reflection becomes zero can be set by adjusting the phase shift angle of the wiring connected to the open-ring resonator, and low reflection and high transmittance can be maintained at the distance between the two distances.

[0144] The above explains the case where the resistance of the power supply is a finite value of 50 Ω, which is the same as the impedance of the power transmission and reception lines. It is preferable to use a zero ohm power supply for high efficiency in power transmission. When using an open ring resonator, it is also possible to take measures against the dependency of the reflectance on the k value by generating the same reactance using a lossless capacitor, inductor, or characteristic impedance line, just like the LC resonator.

[0145] First, in order to achieve impedance matching, a voltage source with an output impedance of 0Ω is used as the power source, and the power source is connected to the input line 1913 via a resistor of 100Ω in the single resonator configuration, and via a resistor of 50Ω in the multiple resonator configuration. This is the condition under which impedance matching is achieved in the power source section.

[0146] In the case of the multi-resonator configuration, the phase shift angles of the wiring are 55° and 125° on the transmitting side and 35° and 145° on the receiving side. The transmittance in this case is shown by line 2005, and the reflectance is shown by line 2006. As explained in Fig. 20, in the single-resonator configuration, the reflectance is 0 when the inter-ring distance is 4.5 mm, and in the multi-resonator configuration, the reflectance is 0 when the inter-ring distance is 3.2 mm and 5.6 mm, and impedance matching is achieved between the power supply and the load.

[0147] 21 is a diagram showing the effect of the feed-side line length on the transmitted power of a single resonator configuration, where line 2101 shows the power consumption of the load, and line 2102 shows the power consumption of the power supply resistor.

[0148] 22 is a diagram showing the effect of the feed-side line length on the transmitted power of a multi-resonator configuration. Line 2201 shows the power consumption of the load, and line 2202 shows the power consumption of the power supply resistor.

[0149] In both the single-cavity and multiple-cavity configurations, the power consumption of the load at the ring distance where the reflectance is zero is approximately 25 W, and the power consumption of the power supply resistor is approximately 25 W. Since there is a loss in the open ring section, it is not exactly 25 W.

[0150] As a result, of the total power consumption of 50W seen from the power supply, half is shared between the power supply resistance and the load. This shows that half of the input power is wasted by the power supply resistance, even though there is no reflection. In this state, even if the signal line length in the single resonator configuration or the line lengths of the input line 1913 and output line 1923 in the multiple resonator configuration are changed, there is no reflection anywhere, so there is no effect on the transmitted power.

[0151] Next, consider the case of Fig. 13B. The resonant power transmitting circuit 700 is a circuit using the open ring resonator of Fig. 19. The capacitance value is a value that has the same impedance value as the matching resistor, and is 0.65 pF in a single resonator configuration and 1.3 pF in a multiple resonator configuration. The capacitor 1331 is installed between the output of the zero ohm power supply and the branch point 1916, which is the input part of the resonator pair.

[0152] The dependency of the power consumption of the load on the distance between the rings in this case is shown by line 2103 in Fig. 21 for the single-resonator configuration and by line 2203 in Fig. 22 for the multi-resonator configuration, where the cable length on the power supply side is set to zero.

[0153] In both cases, it can be seen that the load consumes almost twice as much power as the lines 2101 and 2201, which show the cases where matching resistors are inserted. This shows that the power is consumed by the load without loss. In the case of the multi-resonator configuration, the power is almost constant at inter-ring distances of approximately 3 mm to 6 mm, and is consumed by the load without loss.

[0154] In microwave circuits, since the wavelength is short, devices are usually connected with impedance lines. In this case, if the impedances between the power supply and the resonator, between the resonator and the load, and between the device and the cable are matched, there is no reflected wave, so there is no problem even if the cable length changes. However, if a zero-ohm power supply or a reactance circuit is connected, reflections occur between the cable and the power supply, and between the cable and the reactance circuit, adversely affecting the circuit operation. Therefore, an impedance line is connected as an input line 1913 between the part where the capacitor is connected to the zero-ohm power supply and the branch point 1916 which is the input part of the open ring resonator, and the power consumption of the load when the length of the impedance line is changed in 10° increments from 0° to 360° as a phase shift angle is shown by lines 2104 and 2204. Since there is no loss in the input line 1913, the power consumption of the load is the power sent out by the power supply.

[0155] In both configurations, the power consumption of the load varies depending on the line length except for the distance between the rings where the reflectance becomes zero. In particular, in the single resonator configuration, the fluctuation is large when the impedance is deviated from the impedance-matched distance, so the line length must be adjusted accurately.

[0156] On the other hand, in the multi-resonator configuration, the amount of change between the distance between the two matched rings is kept low. In other words, the multi-resonator configuration not only can transmit a constant amount of power over a wide range of inter-ring distances, but it also has high tolerance to variations in wiring length. On the power receiving side, since impedance matching with the load is established, there is no dependency on the line length of the signal line.

[0157] (3 or more tracks) In the above explanation, the case where the lines to the power source and the load are divided into two has been explained, but the number is not limited to two. A wireless power transmission device using three or more resonator pairs can also be used. Even when divided into three or more lines, a first phase shift circuit is connected to each line at a branch point, a resonator pair including a power transmitting coil and a power receiving coil is connected to each phase shift circuit, a second phase shift circuit is connected to each resonator pair, and each second phase shift circuit is connected at a branch point (coupling point). Also, even when divided into three or more lines, the coupling coefficient of each resonator pair is the same value. It is difficult to determine the phase shift angle when divided into three or more lines graphically, as in the case of dividing into two lines, but it can be determined with high accuracy by using an optimization program of a circuit simulator, etc.

[0158] Figure 23 shows the reflection and transmission characteristics when the SS-type resonant power transmission circuit used in Figures 10 and 11 is used, and the line is divided into 2, 3, and 4, and an optimization program is used for each to determine the phase shift amount of all phase-shift circuits on the transmitting and receiving sides to minimize reflection within a certain k value range. The target k value range and the phase shift angle obtained in the optimization are shown in Table 3. The line impedance of the single line was set to 10 Ω for two or three lines so that the flattest matching is achieved at k = 0.1, but for four lines, the lower k value is also important, so it was set to 1 Ω, which is the flattest at k = 0.01. [Table 3]

[0159] The transmittance in the case of two lines is shown by line 2301, and the reflectance by line 2304. According to line 2301 showing the transmittance, the range of high efficiency is almost the same as the range of high efficiency shown by line 1105 in Fig. 11, and it can be seen that the optimization program can be adjusted with sufficient precision.

[0160] The transmittance in the case of three lines is shown by line 2302, the reflectance by line 2305, and the transmittance in the case of four lines is shown by line 2303, and the reflectance by line 2306, and it can be seen that the range of high efficiency increases as the number of lines increases. Increasing the number of lines increases the number of resonators, which makes the device larger, but it can be seen that the benefits outweigh this.

[0161] In addition, although the above description has been given of the case where an LC resonator using a coil and an open ring resonator are used as the resonator of the resonant power transmission device, the resonator is not limited to this. As shown in Non-Patent Document 5, which shows an example of coupling by an electric field using an antenna instead of a coil, the present invention can be applied to resonators other than coils and antennas, in which the coupling coefficient changes without changing the resonant frequency when the positional relationship between the resonators changes, and the reflection becomes zero when formulas (4) and (5) are satisfied.

[0162] Although the specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The scope of the claims includes various modifications and alterations of the specific examples exemplified above.

[0163] According to the AC signal transmission device of the present disclosure, since the change in the transmission characteristics caused by the change in the coupling coefficient can be suppressed over a wide range, a complex adjustment circuit for contactless power transmission is not required, and a stable contactless power transmission device can be realized with a simple and inexpensive configuration. This can also contribute to the spread of electric vehicles that require frequent charging. [Industrial Applicability]

[0164] The technology disclosed herein can be used in AC signal transmission devices and AC devices. [Explanation of symbols]

[0165] 110, 210 Load or power supply 120, 220, 320, 350, 411, 422 capacitors 130, 230 coil 330, 413, 713, 733 Transmitting coil 340, 423, 723, 743 receiving coil 310 AC power supply 360, 1320 Load 410, 420 terminals 701 Input terminal 702, 752, 1916, 1926 Turning Point 700 Resonant power transmission circuit 751 Output terminal 810, 820 Resonator coil substrate 830 Rotation axis of resonator coil substrate 1310 Zero Ohm Power Supply 1330 Resistance 1331 Capacitor 1332 Inductor 1333 Impedance Line 1911, 1912, 1921, 1922 Open ring resonator 1913 Input line 1914, 1915 Microstrip line as input phase shift circuit 1923 Output line 1924, 1925 Microstrip line as output phase shift circuit

Claims

1. A transmission line; a plurality of first phase shift circuits connected to the transmission line at branch points; a plurality of resonator pairs connected to the plurality of first phase shift circuits, respectively; a plurality of second phase shift circuits connected to the plurality of resonator pairs, the plurality of second phase shift circuits are connected at a junction; AC signal transmission device.

2. The coupling coefficients of the plurality of resonator pairs are the same even if the coupling state changes.

2. An AC signal transmission device according to claim 1.

3. Each of the resonator pairs includes a coil and a capacitor.

3. An AC signal transmission device according to claim 1 or 2.

4. Each of the resonators constituting each of the plurality of resonator pairs is an open ring resonator.

3. An AC signal transmission device according to claim 1 or 2.

5. The transmission line is connected to a zero ohm power supply via a reactance element or an impedance line.

2. An AC signal transmission device according to claim 1.

6. The plurality of first phase-shift circuits have phase-shift angles set so as to match with at least two of the coupling coefficients.

3. The AC signal transmission device according to claim 2.

7. A transmission line; A plurality of phase shift circuits connected to the transmission line at branch points; a resonator connected to each of the plurality of phase shift circuits; An alternating current device having

8. The resonator is a resonator including a coil and a capacitor.

8. An alternating current device as claimed in claim 7.

9. The resonator is an open ring resonator.

8. An alternating current device as claimed in claim 7.

10. A coupling coefficient of a resonator pair constituted by each of the plurality of resonators has the same value even if a coupling state changes.

8. An alternating current device as claimed in claim 7.

11. The phase shifting circuits are set to have phase shift angles that match with at least two of the coupling coefficients.

11. An alternating current device according to claim 10.

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