JP2013223338A - Power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission system capable of suppressing unnecessary current from running through an external conductor in a coaxial cable.SOLUTION: Between coaxial cables 215, 225, which are connected with each of a transmission device 110 having two electrodes 111, 112 and inductors 113, 114 and a reception device 120 having two electrodes 121, 122 and inductors 123, 124, and the transmission device 110 and the reception device 120, there is provided unnecessary-resonance suppression circuits 315, 325 for suppressing an unnecessary resonance.

Description

  The present invention relates to a power transmission system.

  In recent years, a power transmission system using a method called a magnetic field resonance method using an electromagnetic resonance phenomenon has attracted attention.

  Currently, the electromagnetic induction type non-contact power feeding method that is already widely used needs to share the magnetic flux between the power transmission side and the power reception side, and in order to send power efficiently, the power transmission side and the power reception side are placed close to each other. It is necessary to arrange, and the alignment of the connection is also important.

  On the other hand, the non-contact power supply method using the electromagnetic resonance phenomenon can transmit power at a greater distance than the electromagnetic induction method due to the principle of the electromagnetic resonance phenomenon, and transmission efficiency is low even if the alignment is somewhat poor. There is an advantage of not falling. The electromagnetic resonance phenomenon includes an electric field resonance method in addition to a magnetic field resonance method.

  For example, Patent Literature 1 discloses a wireless power feeding system that employs a magnetic field resonance method.

  In the technique disclosed in Patent Document 1, power is transmitted from a power supply coil connected to a power supply circuit to a resonance coil by electromagnetic induction, and adjustment of frequency and Q value is connected to the resonance coil. This is done with capacitors and resistors.

JP 2001-185939 A

  By the way, in such a power transmission system using electromagnetic resonance or electric field resonance, unnecessary resonance may occur due to an impedance component such as a floating capacitor included in a coaxial cable connected to the power transmission side or the power reception side. In addition, there is a problem that unnecessary current flows through the outer conductor of the coaxial cable, which may cause unnecessary current to be generated in a nearby conductive member, and also causes a loss of power transmission.

  Then, this invention aims at providing the electric power transmission system which can suppress an unnecessary resonance.

In order to solve the above problem, the present invention provides a power transmission system that transmits AC power from a power transmission device to a power reception device, wherein the power transmission device is disposed at a predetermined distance and includes the predetermined distance. First and second electrodes having a total width of λ / 2π or less, which is a near field, and the first and second electrodes and the two output terminals of the AC power generation unit are electrically connected to each other. A first suppression unit that is inserted between one coaxial cable, the first coaxial cable, and the first and second electrodes, and suppresses the occurrence of unnecessary resonance at a frequency other than the frequency of the AC power generation unit; And a first inductor inserted between at least one of the first suppression unit and the first electrode and between the first suppression unit and the second electrode, and the power receiving device is separated by a predetermined distance. Placed in place The third and fourth electrodes having a total width including a constant distance of λ / 2π or less, which is a near field, and the third and fourth electrodes and the two input terminals of the load are electrically connected to each other. The second coaxial cable, the second coaxial cable, and second suppression means that is inserted between the third and fourth electrodes and suppresses the occurrence of unnecessary resonance at a frequency other than the frequency of the AC power generation unit. And a second inductor inserted between at least one of the second suppression means and the third electrode and between the second suppression means and the fourth electrode.
According to such a configuration, it is possible to suppress unnecessary current from flowing to the outer conductor of the coaxial cable.

According to another aspect of the invention, in addition to the above-described invention, the first and second suppression means may be configured such that the first to third coils connected in series are wound around a magnetic core, and the first or second coil is disposed at the end of the first coil. A central conductor of the second coaxial cable is connected, an outer conductor of the first or second coaxial cable is connected to a connection portion between the second coil and the third coil, a connection portion between the first coil and the second coil, and the first coil The first and second electrodes or the third and fourth electrodes are connected to end portions of three coils.
According to such a configuration, unnecessary radiation can be suppressed with a simple configuration and with a small loss.

In addition to the above-mentioned invention, the fifth and sixth electrodes according to another invention are arranged at a predetermined distance and have a total width including the predetermined distance of a length of λ / 2π or less that is a near field. And a third inductor connected between the fifth and sixth electrodes, and the fifth and sixth electrodes include the first and second electrodes of the power transmission device, A resonance frequency of a coupler that is disposed between the third and fourth electrodes of the power receiving device and is configured by the fifth and sixth electrodes and the third inductor is determined by the coupler of the power transmitting device and the power receiving device. The resonance frequency is set to be approximately equal to the resonance frequency.
According to such a configuration, it is possible to suppress unnecessary current from flowing to the outer conductor of the coaxial cable and to increase the transmission distance.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the electric power transmission system which can transmit electric power efficiently.

It is a figure for demonstrating the principle of operation of embodiment of this invention. It is an equivalent circuit of embodiment shown in FIG. It is a figure which shows the transmission characteristic of the equivalent circuit shown in FIG. It is a figure which shows the structural example of the coupler for power transmission which concerns on embodiment of this invention. It is a figure which shows the structural example of the coupler for power transmission which concerns on embodiment of this invention, and the coupler for power reception. It is a Smith chart of the input impedance of the coupler for power transmission of embodiment shown in FIG. It is a figure which shows the frequency characteristic of parameter S11, S21, (eta) 21 of embodiment shown in FIG. It is a figure for demonstrating the usage type of embodiment shown in FIG. It is a figure which shows the impedance of each part of embodiment shown in FIG. 5 is an equivalent circuit of the embodiment shown in FIG. 4. It is a figure which shows the structural example of 1st Embodiment of this invention. It is a figure which shows the structural example of the unnecessary resonance suppression circuit shown in FIG. It is an equivalent circuit of embodiment shown in FIG. It is a figure which shows the frequency characteristic of transmission efficiency (eta) 21 of embodiment shown in FIG. 12 is a Smith chart of return loss in the embodiment shown in FIG. 11. It is a figure which shows the structural example of 2nd Embodiment of this invention. It is a figure which shows the structural example of the coupler for relay shown in FIG. It is a figure which shows the structural example of 3rd Embodiment of this invention. It is a figure which shows the structural example of 4th Embodiment of this invention. It is a figure which shows the structural example of 5th Embodiment of this invention.

  Next, an embodiment of the present invention will be described.

(A) Description of Operation Principle of Embodiment First, before describing the first embodiment, the operation principle of the present invention will be described. FIG. 1 is a diagram for explaining an operation principle of a power transmission system 1 according to an embodiment of the present invention. In the example of this figure, the power transmission system 1 includes a power transmission device 10 and a power reception device 20.

  Here, the power transmission device 10 includes electrodes 11 and 12, inductors 13 and 14, connection lines 15 and 16, and an AC power generation unit 17. The power receiving device 20 includes electrodes 21 and 22, inductors 23 and 24, connection lines 25 and 26, and a load 27. The electrodes 11 and 12 and the inductors 13 and 14 constitute a power transmission coupler. The electrodes 21 and 22 and the inductors 23 and 24 constitute a power receiving coupler.

  Here, the electrodes 11 and 12 are comprised by the member which has electroconductivity, and are arrange | positioned at predetermined distance d1. In the example of FIG. 1, as the electrodes 11, 12, 21, and 22, flat plate electrodes having a rectangular shape having substantially the same size are illustrated. The electrode 11 and the electrode 21 are arranged in parallel so as to face each other with a distance d2, and the electrode 12 and the electrode 22 are also arranged in parallel so as to face each other with the same distance d2. The electrodes 11, 12, 21, and 22 may be electrodes having shapes other than those shown in FIG. For example, it may be a circular or elliptical plate electrode, a three-dimensional shape such as a sphere, or a curved or bent electrode instead of a flat plate.

  The total width D including the distance d1 between the electrode 11 and the electrode 12 is set to be narrower than the near field indicated by λ / 2π where λ is the wavelength of the electric field radiated from these electrodes. . Similarly, the total width D including the distance d1 between the electrode 21 and the electrode 22 is set to be narrower than the near field indicated by λ / 2π. Also, the distance d2 between the electrode 11 and the electrode 21 and between the electrode 12 and the electrode 22 is set to be shorter than the near field indicated by λ / 2π.

  For example, the inductors 13 and 14 are configured by winding a conductive wire (for example, copper wire), and one end of each of the inductors 13 and 12 is electrically connected to the ends of the electrodes 11 and 12 in the example of FIG. . The connection line 15 is composed of a conductive wire (for example, copper wire) that connects the other end of the inductor 13 and one end of the output terminal of the AC power generation unit 17. The connection line 16 is formed of a conductive wire material that connects the other end of the inductor 14 and the other end of the output terminal of the AC power generation unit 17. The connection lines 15 and 16 are constituted by coaxial cables or balanced cables.

  The AC power generation unit 17 generates AC power having a predetermined frequency and supplies the AC power to the inductors 13 and 14 via the connection lines 15 and 16.

  Similarly to the electrodes 11 and 12, the electrodes 21 and 22 are made of a conductive member, and are arranged at a predetermined distance d1.

  For example, the inductors 23 and 24 are formed by winding a conductive wire. In the example of FIG. 1, one end of each of the inductors 23 and 22 is electrically connected to the end of the electrodes 21 and 22. The connection line 25 is composed of a conductive wire (for example, copper wire) that connects the other end of the inductor 23 and one end of the input terminal of the load 27. The connection line 26 is formed of a conductive wire that connects the other end of the inductor 24 and the other end of the input terminal of the load 27. The connection lines 25 and 26 are constituted by coaxial cables or balanced cables.

  The load 27 is supplied with power output from the AC power generation unit 17 and transmitted via the power transmission coupler and the power reception coupler. The load 27 is constituted by, for example, a rectifier and a secondary battery. Of course, it may be other than this.

  FIG. 2 is a diagram showing an equivalent circuit of the power transmission system 1 shown in FIG. In FIG. 2, impedance 2 indicates the output impedance of the AC power generation unit 17 and has a value of Z0. Impedance 27 indicates the input impedance of the load 27 and has a value of Z0. Note that the characteristic impedance of the connection lines 15 and 16 and the connection lines 25 and 26 not explicitly shown in the equivalent circuit is Z0. The inductor 3 corresponds to the power transmission side inductors 13 and 14 and has an element value of L. The capacitor 4 has an element value (C obtained by subtracting a capacitor having an element value Cm generated between the power transmitting side electrodes 11 and 12 and the power receiving side electrodes 21 and 22 from a capacitor having an element value C generated between the power transmitting side electrodes 11 and 12. -Cm). The capacitor 5 indicates a capacitor generated between the power transmission side electrodes 11 and 12 and the power reception side electrodes 21 and 22, and has an element value of Cm. The capacitor 6 has an element value (C) obtained by subtracting the capacitor of the element value Cm generated between the power transmission side electrodes 11 and 12 and the power reception side electrodes 21 and 22 from the capacitor of the element value C generated between the power reception side electrodes 21 and 22. -Cm). The inductor 7 corresponds to the inductors 23 and 24 on the power receiving side and has an element value of L.

FIG. 3 shows the frequency characteristics of the S parameter between the power transmission device 10 and the power reception device 20. However, the port impedance of the S parameter is defined by Z0 which is the same as the characteristic impedance of the feeding cable. Specifically, the horizontal axis of FIG. 3 indicates the frequency, and the vertical axis indicates the insertion loss (S21) from the power transmission device 10 to the power reception device 20. As shown in FIG. 3, the insertion loss from the power transmitting apparatus 10 to the power receiving apparatus 20 has an impedance maximum point at the frequency f _C and has impedance matching points, that is, resonance points at the frequencies f _L and f _H. ing. Here, the frequency f _C is determined by the inductance value L of the inductors 3 and 7 shown in FIG. 2 and the capacitance value C of the capacitor formed by the electrodes 11 and 12 or the electrodes 21 and 22. Further, the frequencies f _L and f _H correspond to the inductance value L of the inductors 3 and 7 shown in FIG. 2, the capacitance value Cm of the capacitor formed by the electrodes 11 and 12 and the electrodes 21 and 22, and the electrodes 11 and 12. And the capacitance value C of the capacitor generated between the electrodes 21 and 22, respectively, are approximated.

The frequency of the AC power generated by the AC power generator 17 is set to be equal to f _L or f _H shown in FIG. Thus, by setting the frequency of the AC power generation unit 17, the insertion loss from the power transmission device 10 to the power reception device 20 becomes approximately 0 dB. Therefore, power is transmitted from the power transmission device 10 to the power reception device 20 without loss. Can be sent.

  In the embodiment illustrated in FIG. 1, the electrodes 11 and 12 of the power transmission device 10 and the electrodes 21 and 22 of the power reception device 20 are coupled by electric field resonance, and the electrodes 11 and 12 of the power transmission device 10 to the electrodes 21 of the power reception device 20. AC power is transmitted to 22 by an electric field.

  That is, in the embodiment shown in FIG. 1, the electrodes 11 and 12 of the power transmission device 10 and the electrodes 21 and 22 of the power reception device 20 are arranged apart by a distance d2 shorter than λ / 2π that is the near field. The electrodes 21 and 22 are arranged in a region where the electric field component radiated from the electrodes 11 and 12 is dominant. Further, the resonance frequency by the capacitor and inductors 13 and 14 formed between the electrodes 11 and 12 and the resonance frequency by the capacitor and inductors 23 and 24 formed between the electrodes 21 and 22 are set to be substantially equal. Has been. Thus, since the electrodes 11 and 12 of the power transmission device 10 and the electrodes 21 and 22 of the power reception device 20 are coupled by electric field resonance, the electrodes 11 and 12 of the power transmission device 10 are changed to the electrodes 21 and 22 of the power reception device 20. On the other hand, AC power is efficiently transmitted by the electric field.

(B) Description of Configuration of Embodiment Next, a first embodiment of the present invention will be described. In the following, first, a configuration without an unnecessary resonance suppression circuit will be described, and then a first embodiment having an unnecessary resonance suppression circuit will be described.

  4 and 5 are perspective views showing a configuration example without an unnecessary resonance suppression circuit. Here, FIG. 4 shows a configuration example of the power transmission coupler 110 according to the embodiment. FIG. 5 is a perspective view showing a state in which the power transmission coupler 110 and the power reception coupler 120 are arranged.

  As shown in FIG. 4, the power transmission coupler 110 is configured by a conductive member having a rectangular shape on a front surface 118 </ b> A of a circuit board 118 configured by an insulating member having a rectangular plate shape. The electrodes 111 and 112 to be arranged are arranged. In the example of FIG. 4, no electrode or the like is disposed on the back surface 118 </ b> B of the circuit board 118. As a specific configuration example, for example, electrodes 111 and 112 are formed of a conductive thin film such as copper on a circuit board 118 formed of a glass epoxy board, a glass composite board, or the like. The electrodes 111 and 112 are arranged in parallel at positions separated by a predetermined distance d1. The width D of the electrodes 111 and 112 including the distance d1 is set to be narrower than the near field indicated by λ / 2π when the wavelength of the electric field radiated from these electrodes is λ. . As a specific length of D, for example, when the operating frequency is 13.56 MHz, it can be about 50 cm, and the length L in the direction orthogonal to this can be about 50 cm.

  One ends of inductors 113 and 114 are connected to the ends of the electrodes 111 and 112 of the circuit board 118 in the short direction. The other ends of the inductors 113 and 114 are connected to one ends of connection lines 115 and 116, respectively. The connection lines 115 and 116 are disposed so as to avoid the regions of the electrodes 111 and 112 and the region sandwiched between them, and are disposed so as to extend in a direction away from these regions (lower left direction in FIG. 4). Yes. More specifically, the rectangular regions of the electrodes 111 and 112 and the region sandwiched between the two electrodes 111 and 112 are arranged so as to avoid the region, and the electrodes 111 and 112 are arranged so as to extend away from these regions. ing. By arranging in this way, interference between the electrodes 111 and 112 and the connection lines 115 and 116 can be reduced, so that a reduction in transmission efficiency can be prevented. The connection lines 115 and 116 are configured by, for example, a coaxial cable or a balanced cable. Note that the other ends of the connection lines 115 and 116 are respectively connected to output terminals of an AC power generation unit (not shown). By connecting the AC power generation unit to the power transmission coupler 110 by the connection lines 115 and 116, a power transmission device is configured.

The power transmission coupler 110 constitutes a series resonance circuit composed of the capacitance C of the capacitor formed by arranging the electrodes 111 and 112 at a predetermined distance d1 and the inductance L of the inductors 113 and 114. It has a unique resonance frequency f _C.

The power receiving coupler 120 has the same configuration as that of the power transmitting coupler 110. On the surface 128A of the circuit board 128, electrodes 121 and 122 and inductors 123 and 124 made of a conductive member having a rectangular shape are arranged. Connection lines 125 and 126 are connected to the other ends of the inductors 123 and 124. The capacitance C of the capacitor formed by the electrodes 121 and 122 and the resonance frequency f _C of the series resonance circuit due to the inductance L of the inductors 123 and 124 are set to be substantially the same as those of the power transmission coupler 110. The connection lines 125 and 126 are configured by, for example, a coaxial cable or a balanced cable. A load (not shown) is connected to the other ends of the connection lines 125 and 126 of the power receiving coupler 120. A power receiving device is configured by connecting a load to the power receiving coupler 120 through the connection lines 125 and 126.

  FIG. 5 is a diagram illustrating a state in which the power transmission coupler 110 and the power reception coupler 120 are arranged to face each other. As shown in this figure, the power transmission coupler 110 and the power reception coupler 120 are arranged so that the circuit boards 118 and 128 are parallel to each other with a distance d2 so that the surfaces 118A and 128A of the circuit boards 118 and 128 face each other. Is done. The power transmission coupler 110 and the power reception coupler 120 are configured so that the electric field generated between the two electrodes 111 and 112 of the power transmission coupler 110 and the electric field generated between the two electrodes 121 and 122 of the power reception coupler 120 are substantially parallel. When the position in the x direction of the gap between the two electrodes 111 and 112 of the power transmission coupler 110 and the position in the x direction of the gap between the two electrodes 121 and 122 of the power reception coupler 120 are substantially the same, Transmission is possible.

Next, the operation of the embodiment shown in FIG. 5 will be described. FIG. 6 shows a Smith chart of the impedance S11 of the power transmission coupler 110 when the power transmission coupler 110 and the power reception coupler 120 are arranged to face each other with a distance of 40 cm (d2 = 40 cm). In this case, the port impedance of the measuring instrument is the characteristic impedance Z0 of the connection line (real value)
Is set to a value equal to As shown in this figure, in the present embodiment, the impedance locus of the power transmission coupler 110 and the power reception coupler 120 passes near the center of the Smith chart circle, so that transmission is performed in the vicinity of this. Thus, reflection can be suppressed and power can be transmitted efficiently.

  FIG. 7 is a diagram showing the frequency characteristics of the S parameter between the power transmission coupler 110 and the power reception coupler 120 when the power transmission coupler 110 and the power reception coupler 120 are disposed to face each other with a distance of 40 cm (d2 = 40 cm). is there. In this figure, the solid line indicates the frequency characteristic of the absolute value of the parameter S21, the broken line with a long interval indicates the frequency characteristic of the absolute value of the parameter S11, and the broken line with a short interval indicates the transmission efficiency η21 (= | S21 | ^ 2). The frequency characteristics are shown. Here, the parameter S11 indicates the reflection of the signal input from the power transmission coupler 110, the parameter S21 indicates the signal passing from the power transmission coupler 110 to the power reception coupler 120, and the transmission efficiency η21 is for power reception from the power transmission coupler 110. The signal transmission efficiency to the coupler 120 is shown. As shown in FIG. 7, at the frequency of 13.56 MHz, the reflection of the signal input to the power transmission coupler 110 is minimized and the transmission from the power transmission coupler 110 to the power reception coupler 120 is maximized. As a result, the signal transmission efficiency η21 from the power transmission coupler 110 to the power reception coupler 120 is maximized at about 97%. That is, it can be said that the impedance of the power transmission system 1 is matched at d = 40 cm.

  FIG. 8 is a diagram illustrating an actual usage example. In the example of FIG. 8, the coaxial cable 215 and the coaxial cable 225 are used as the connection lines 115 and 116 and the connection lines 125 and 126. The central conductor of the coaxial cable 215 is connected to the inductor 113, and the outer conductor is connected to the inductor 114. The central conductor of the coaxial cable 225 is connected to the inductor 123, and the outer conductor is connected to the inductor 124.

  FIG. 9 is an equivalent circuit of the power transmission coupler 110 configured as shown in FIG. As shown in FIG. 9, the coaxial cable 215 has a center conductor 215a and an outer conductor 215b. The characteristic impedance of the coaxial cable is set to a value equal to Z0 which is the value of the output impedance 211 of the power supply 210. The impedance 212 indicated by Zg is an impedance generated between the electrode of the power transmission coupler and the ground, for example, an impedance generated by a stray capacitance or the like. Impedances 213 and 214 indicate equivalent impedances of the electrodes of the power transmission coupler 110.

Regarding the potential of the electrode of the power transmission coupler, the potential of the coaxial cable center conductor connection portion of the electrode 213 is Va, the potential of the gap area between the electrode 213 and the electrode 214 is Vb, and the potential of the coaxial cable outer conductor connection portion of the electrode 214 is Vg. Stipulate. Since Vg is the same potential as GND, it becomes 0. When the impedances of the electrode 213 and the electrode 214 are equal, Vb is Va / 2. Accordingly, since the gap area between the electrode 213 and the electrode 214 has a potential with respect to the GND, when the impedance 212 is equivalently connected between the gap area and the GND, the electrode 213 or the electrode 214 is displaced with respect to the GND. current _{I 3} flows. The displacement current I ₃ flows through GND as a normal current, and then returns to the inner conductor of the coaxial cable 215 through the outer conductor of the coaxial cable 215. That is, a current path in a form including the GND and the coaxial cable outer conductor is generated. When such a current _{I 3} flows, shown in FIG. 10 (A), the equivalent circuit of Figure 2, as shown in FIG. 10 (B), relative to the capacitor 4 and the capacitor 6, respectively, corresponding to the impedance 212 The impedances 212a and 212b are connected in parallel. That is, the configuration parameters of the equivalent circuit of the power transmission system 1 shown in FIG. 1 change, and resonance (unnecessary resonance) occurs at a frequency different from the original resonance frequency. Such unnecessary resonance causes unnecessary current to flow in the outer conductor of the coaxial cable, which may cause unnecessary current to be generated in a nearby conductive member, and may lead to loss of power transmission.

  FIG. 11 is a diagram illustrating a configuration example of the first embodiment of the present invention. As shown in FIG. 11, in the first embodiment, an unnecessary resonance suppression circuit 315 is inserted between the coaxial cable 215 and the power transmission coupler 110 shown in FIG. 8, and between the coaxial cable 225 and the power reception coupler 120. An unnecessary resonance suppression circuit 325 is inserted in the circuit.

  FIG. 12 is a diagram illustrating a detailed configuration example of the unnecessary resonance suppression circuit 315 illustrated in FIG. 11. The unnecessary resonance suppression circuit 325 has the same configuration as that in FIG. As shown in FIG. 12, the unnecessary resonance suppression circuit 315 has three coils 315a to 315c connected in series. The coils 315a to 315c are wound around a magnetic core having a toroidal shape or a rod shape made of, for example, ferrite. In addition, the black dot attached | subjected to the left side of the coils 315a-315c has shown the winding start. One end of the coil 315a is connected to the central conductor 215a of the coaxial cable 215 via the terminal t1, and the other end of the coil 315a is connected to the inductor 113 via the terminal t3 and to one end of the coil 315b. The other end of the coil 315b is connected to the outer conductor 215b of the coaxial cable 215 via the terminal t2, and is also connected to one end of the coil 315c. The other end of the coil 315c is connected to the inductor 114 via a terminal t4. The circuit shown in FIG. 12 may be enclosed in a metal shield case as shown in FIG. 11, for example, in order to prevent radiation of electromagnetic waves. Of course, you may make it use as it is, without enclosing in a shield case.

  FIG. 13 is an equivalent circuit of the power transmission coupler 110 of the first embodiment shown in FIG. In the example of FIG. 13, an unnecessary resonance suppression circuit 315 shown in FIG. 12 is connected between the coaxial cable 215 and the impedances 213 and 214 as compared with the equivalent circuit shown in FIG. 9. Note that the power receiving coupler 120 has the same configuration as that in FIG.

  Next, the operation of the first embodiment will be described. In FIG. 12, when an AC voltage is applied to the terminals t1 and t2 from the AC power generator 210 via the coaxial cable 215, a current flows through the coils 315a and 315b. As a result, an induced voltage is also generated by electromagnetic induction in the coil 315c wound around the same magnetic core. Here, since the coil 315c has the same number of turns as the coils 315a and 351b, the same voltage is generated in the coil 315b and the coil 315c, and this voltage is applied to the inductors 113 and 114.

With the above operation, in FIG. 13, the potential of the coaxial cable central conductor connection portion 315a is Va, the potential of the connection portion 315b of 315b is Vb, the potential of the coaxial cable outer conductor connection portion of 315c is Vg, and the electrode 214 of 315c is the same. Vb is Vb = Va / 2 and Vc = −Va / 2 when the coils 315a to 315c have the same electrical characteristics. Vg is 0 because it is directly connected to GND. Therefore, the potential of the connection portion of the electrode 213 with the 315a is Vb, that is, Va / 2, and the potential of the connection portion of the electrode 214 with the 315c is −Va / 2 as described above, and thus the gap area between the electrode 213 and the electrode 214 Is equal to the potential Vg of GND, that is, 0. Since no potential difference occurs in the impedance Zg, the displacement current I ₃ is zero. This means that the impedance 212 does not affect the power transmission coupler 110. 10, this means that the power transmission side impedance 212a and the power reception side impedance 212b shown in FIG. 10B are excluded and the state shown in FIG. 10A is restored. In other words, application of the unnecessary resonance suppression circuit 315 can suppress occurrence of unnecessary resonance due to the impedance 212.

  FIG. 14 is a diagram showing frequency characteristics of the transmission efficiency η21 of the embodiment shown in FIGS. Here, the transmission efficiency η21 is a value obtained by the square of the absolute value of S21, which is the S parameter (= | S21 | ^ 2). 14, the broken line indicates the characteristics of the configuration shown in FIG. 8, and the solid line indicates the characteristics of the first embodiment shown in FIG. The distance d2 between the power transmission coupler 110 and the power reception coupler 120 is set to 20 cm. From comparison of these graphs, unnecessary resonance occurs in the vicinity of 22 MHz in the configuration shown in FIG. 8, while no unnecessary resonance occurs in the first embodiment shown in FIG. 11. Note that at the resonance frequency of 27.12 MHz, there is a peak in transmission efficiency in both the embodiment of FIG. 8 and FIG. Here, the transmission efficiency at 27.12 MHz of the configuration shown in FIG. 8 is 79.7%, while the transmission efficiency at 27.12 MHz in the first embodiment shown in FIG. 11 is 78.2%, which is unnecessary. The loss due to the insertion of the resonance suppression circuit can be ignored.

  FIG. 15 is a Smith chart showing the return loss S11 of the power transmission coupler 110 of the embodiment shown in FIGS. In this figure, the broken line indicates the characteristics of the configuration shown in FIG. 8, and the solid line indicates the characteristics of the first embodiment shown in FIG. From comparison of these graphs, the trajectory is doubled in the configuration shown in FIG. 8, and the inner trajectory indicates a trajectory associated with unnecessary resonance. On the other hand, in the first embodiment shown in FIG. 11, the trajectory is not double and unnecessary resonance does not occur. For this reason, generation | occurrence | production of unnecessary radiation is suppressed.

  As described above, in the first embodiment, the unnecessary resonance suppression circuit 315 is disposed between the coaxial cable 215 and the power transmission coupler 110, and the unnecessary resonance suppression circuit is interposed between the coaxial cable 225 and the power reception coupler 120. Since 325 is arranged, unnecessary resonance can be suppressed, so that unnecessary current can be prevented from flowing to the outer conductor of the coaxial cable.

  Further, as the unnecessary resonance suppression circuits 315 and 325, the configuration using the coils 315a to 315c as shown in FIG. 12 is adopted, so that the circuit can be realized with a simple configuration and the generation of loss can be reduced.

Next, a second embodiment will be described with reference to FIGS. In the second embodiment, as shown in FIG. 16, a relay coupler 130, which is a relay device, is arranged between the power transmission coupler 110 and the power reception coupler 120. In this example, the distance d21 between the power transmission coupler 110 and the relay coupler 130 is 20 cm, and the distance d22 between the relay coupler 130 and the power reception coupler 120 is also 20 cm. Thereby, the distance (transmission distance) between the power transmission coupler 110 and the power reception coupler 120 is 40 cm. FIG. 17 shows a detailed configuration example of the relay coupler 130. The relay coupler 130 is configured by connecting the other ends of inductors 133 and 134 of a coupler having the same configuration as in FIG. Note that these inductors 133 and 134 may have a single configuration. The resonance frequency f _C of the relay coupler 130 is set to be substantially the same as that of the power transmission coupler 110 and the power reception coupler 120. An unnecessary resonance suppression circuit 315 is disposed between the coaxial cable 215 and the power transmission coupler 110, and an unnecessary resonance suppression circuit 325 is disposed between the coaxial cable 225 and the power reception coupler 120.

  As described above, even when the relay coupler 130 is inserted between the power transmission coupler 110 and the power reception coupler 120, unnecessary radiation is suppressed by suppressing unnecessary resonance, as in the first embodiment. Can be suppressed. Further, by arranging the relay coupler 130 in this way, the transmission distance can be extended without increasing the transmission loss.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 18 shows an embodiment in which the power transmission system is applied to a multi-story parking lot. In FIG. 18, the multi-story parking lot 400 includes four support columns 401, and the pallet 402 is disposed on the four support columns 401 at a predetermined distance. In the example of this figure, two pallets 402 are provided, and the vehicle 430 is parked on the lower pallet 402. A power receiving device having a power receiving coupler 416, an unnecessary resonance suppression circuit 417, a charging control circuit 418, a power cable 419, and a connector 420 is disposed at the end of each pallet. In addition, a power transmission device including a power cable 411, a power transmission control circuit 412, a coaxial cable 413, an unnecessary resonance suppression circuit 414, and a power transmission coupler 415 is arranged on the left front column 401. The power transmission coupler 415 and the power reception coupler 416 have the same configuration as that in FIG. 11, and the unnecessary resonance suppression circuits 414 and 417 have the same configuration as that in FIG.

  Here, the pallet 402 is movable up and down when the vehicle is taken in and out. When the vehicle 430 is mounted on the pallet 402 and moved to a predetermined position, the power transmission coupler 415 and the power reception coupler 416 face each other. When the connector 420 is connected to the vehicle 430 by the user, the charging control circuit 418 detects this, and controls the power transmission control circuit 412 to start power transmission. As a result, the power supplied from the support column 421 via the coaxial cable 411 is converted into a high-frequency AC signal by the power transmission control circuit 412 and then transmitted via the power transmission coupler 415 and the power reception coupler 416 for charge control. It is supplied to the secondary battery of the vehicle 430 through the circuit 418. At this time, since unnecessary resonance is suppressed by the unnecessary resonance suppression circuits 414 and 417, it is possible to suppress unnecessary current from flowing to the outer conductor of the coaxial cable.

  As described above, in the third embodiment, by applying the power transmission system to the multistory parking lot 400, even when the pallet 402 moves, power can be transmitted without contact. As compared with the case of connecting by the above, it is possible to improve the degree of freedom of arrangement of the apparatus and to prevent the wiring from being disconnected between machines and the like. Unnecessary resonance suppression circuits 414 and 417 suppress unnecessary current from flowing to the outer conductor of the coaxial cable.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, as illustrated in FIG. 19, the power receiving coupler 120 is disposed at the bottom of the power receiving unit 500 that is disposed on the bottom surface of a forklift that is a transport vehicle for equipment and the like. An unnecessary resonance suppression circuit 315 is connected between the coaxial cable 215 and the power transmission coupler 110, and an unnecessary resonance suppression circuit 325 is connected between the coaxial cable 225 and the power reception coupler 120. Further, relay couplers 130 to 150 are arranged at a predetermined interval on the left side of the power transmission coupler 110. When the forklift moves in the direction of the arrow shown in FIG. 19, the power receiving unit 500 moves, so the power receiving coupler 120 also moves. At this time, in the relay couplers 130 to 150, the connection line (see connection line 135 in FIG. 17) of the relay coupler located on the left side of the relay coupler facing the power receiving coupler 120 is opened. As a result, the relay coupler is invalidated, and power transmission between the power transmission coupler 110 and the power reception coupler 120 is not affected. According to such a configuration, even if the position of the forklift is shifted in the moving direction, charging can be performed with little loss, and unnecessary resonance is suppressed by the action of the unnecessary resonance suppression circuits 315 and 325, It is possible to suppress unnecessary current from flowing to the outer conductor of the coaxial cable.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. In the fifth embodiment, the power transmission coupler 110 is disposed in the ground side device, and the power reception coupler 120 is disposed in the vehicle 600. A relay coupler 130 is disposed on the top surface of the ground side device, and a relay coupler 140 is disposed on the bottom surface of the vehicle 600. A coaxial cable 215 connected to a power transmission circuit (not shown) is connected to the power transmission coupler 110, and a coaxial cable 225 connected to a power reception circuit (not shown) is connected to the power reception coupler 120. An unnecessary resonance suppression circuit 315 is connected between the coaxial cable 215 and the power transmission coupler 110, and an unnecessary resonance suppression circuit 325 is connected between the coaxial cable 225 and the power reception coupler 120.

  In the fifth embodiment, when a secondary battery (not shown) built in the vehicle 600 is charged, the vehicle stops on the relay coupler 130. At this time, the distance between the relay coupler 130 and the relay coupler 140 differs depending on the vehicle type. In the fifth embodiment, the transmission efficiency is maximized between the ground side device (power transmission device) and the device (power reception device) arranged on the vehicle side in order to prevent the transmission efficiency from being different depending on the vehicle type. , These distances are adjusted. As a method for searching for the distance at which the transmission efficiency is maximized, for example, the input impedance of the power transmission coupler 110 is adjusted so as to become a desired impedance (for example, 50Ω), or reflection at the power transmission coupler 110 is performed. It may be adjusted so that is minimized.

  According to the fifth embodiment described above, the power transmission coupler 110 and the power reception coupler 120 are driven by the drive device to adjust the position, so that power can be transmitted with high efficiency regardless of the vehicle type and incorporated in the vehicle. The rechargeable secondary battery can be charged, and unnecessary resonance can be suppressed by the operation of the unnecessary resonance suppression circuits 315 and 325, and unnecessary current can be prevented from flowing to the outer conductor of the coaxial cable.

(C) Description of Modified Embodiment It goes without saying that the above embodiment is merely an example, and the present invention is not limited to the case described above. For example, in the above embodiment, the electrodes of the power transmission coupler 110, the power reception coupler 120, and the relay couplers 130 to 150 have the same size, but they may have different sizes. .

  In the first to fifth embodiments described above, the electrodes of the power transmission coupler 110, the power reception coupler 120, and the relay couplers 130 to 150 are arranged to face each other. It may be arranged in a state slightly shifted in the X direction or Y direction shown in FIG. Alternatively, the power transmission coupler 110, the power reception coupler 120, and the relay couplers 130 to 150 may be disposed so as to relatively rotate by a predetermined angle.

  Further, in each of the embodiments described above, each electrode of the power transmission coupler 110, the power reception coupler 120, and the relay couplers 130 to 150 has a rectangular shape, but may have a circular or elliptical shape instead of a rectangular shape. Good. Alternatively, it may be a curved or bent shape instead of a flat plate shape, or a three-dimensional shape such as a spherical shape.

  Further, the inductors of the power transmission coupler 110, the power reception coupler 120, and the relay couplers 130 to 150 are inserted between the electrodes and the connection lines, but can be inserted in other locations. is there. In the above embodiment, two inductors are provided for each of the power transmission coupler 110, the power reception coupler 120, and the relay couplers 130 to 150. However, one inductor may be provided. Good.

  In each of the above embodiments, the inductor is configured by winding a conductor wire in a cylindrical shape. For example, the inductor has a shape meandering on a plane as used in a microstrip line. Or you may make it comprise by what has a spiral shape on a plane.

  In the above embodiments, the unnecessary resonance suppression circuits 315 and 325 and the inductors 113, 114, 123, and 124 are configured separately. However, for example, the inductors 113 and 114 are used as the magnetic core of the unnecessary resonance suppression circuit 315. These may be wound together to form one configuration. Of course, the inductors 123 and 124 may be wound together with the magnetic core of the unnecessary resonance suppression circuit 325 so as to have one configuration.

  In each of the above embodiments, the unnecessary resonance suppression circuits 315 and 325, the coaxial cables 215 and 225, and the inductors 113, 114, 123, and 124 are directly connected. It may be detachable by using. According to such a configuration, for example, it is possible to select the optimum unnecessary resonance suppression circuits 315 and 325 according to the purpose of use and the usage environment.

DESCRIPTION OF SYMBOLS 1 Electric power transmission system 10 Power transmission apparatus 11,12 Electrode 13,14 Inductor 15,16 Connection line 17 AC power generation part 20 Power receiving apparatus 21,22 Electrode 23,24 Inductor 25,26 Connection line 27 Load 110 Transmission coupler 111,112 Electrode 113, 114 Inductor 115, 116 Connection line 118 Circuit board 120 Power receiving coupler 121, 122 Electrode 123, 124 Inductor 125, 126 Connection line 128 Circuit board 130-150 Relay coupler 131, 132, 141, 142, 151, 152 Electrodes 133, 134, 143, 144, 153, 154 Inductors 135, 145, 155 Connection lines 138, 148, 158 Circuit board 315, 325 Unwanted resonance suppression circuit

Claims (3)

In a power transmission system that transmits AC power from a power transmission device to a power reception device,
The power transmission device is:
First and second electrodes arranged at a predetermined distance and having a total width including the predetermined distance of λ / 2π or less which is a near field;
A first coaxial cable that electrically connects the first and second electrodes and the two output terminals of the AC power generation unit;
First suppression means that is inserted between the first coaxial cable and the first and second electrodes and suppresses the occurrence of unnecessary resonance at a frequency other than the frequency of the AC power generation unit;
A first inductor inserted between at least one of the first suppression means and the first electrode and between the first suppression means and the second electrode;
The power receiving device is:
A third electrode and a fourth electrode arranged at a predetermined distance and having a length equal to or less than λ / 2π, the total width including the predetermined distance being a near field;
A second coaxial cable for electrically connecting the third and fourth electrodes and the two input terminals of the load;
A second suppression means that is inserted between the second coaxial cable and the third and fourth electrodes, and suppresses the occurrence of unnecessary resonance at a frequency other than the frequency of the AC power generation unit;
A second inductor inserted between at least one of the second suppression unit and the third electrode and between the second suppression unit and the fourth electrode;
A power transmission system characterized by that.   In the first and second suppression means, first to third coils connected in series are wound around a magnetic core, a central conductor of the first or second coaxial cable is connected to an end of the first coil, An outer conductor of the first or second coaxial cable is connected to a connection portion between the two coils and the third coil, and the first and second coils are connected to a connection portion between the first coil and the second coil and an end portion of the third coil. The power transmission system according to claim 1, wherein the electrode or the third and fourth electrodes are connected. Fifth and sixth electrodes arranged at a predetermined distance and having a total width including the predetermined distance of λ / 2π or less that is a near field;
A relay device having a third inductor connected between the fifth and sixth electrodes,
The fifth and sixth electrodes are disposed between the first and second electrodes of the power transmitting device and the third and fourth electrodes of the power receiving device,
The resonance frequency of a coupler constituted by the fifth and sixth electrodes and the third inductor is set to be substantially equal to the resonance frequency of the coupler of the power transmission device and the power reception device. Item 3. The power transmission system according to Item 1 or 2.

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