JP5730840B2 - Wireless power transmission system, power transmission device, and power reception device - Google Patents

Description

  The present invention relates to a wireless power transmission system, a power transmission device, and a power reception device.

  Patent Document 1 discloses a wireless power transmission apparatus that transmits power between two non-contact electric circuits using electromagnetic induction.

JP-A-8-340285

  By the way, in the technique disclosed in Patent Document 1, there is a problem in that power cannot be efficiently transmitted because power loss in the coil for transmitting power is large.

  Accordingly, an object of the present invention is to provide a wireless power transmission system, a power transmission device, and a power reception device that can efficiently transmit power.

In order to solve the above problems, the present invention provides a wireless power transmission system that wirelessly transmits AC power from a power transmission device to a power reception device, wherein the power transmission device is disposed at a predetermined distance, A first and second electrodes having a total width including a distance of λ / 2π or less, which is a near field, a first inductor connected between the first and second electrodes, and the first and second First and second connection lines that electrically connect the electrode and the two output terminals of the AC power generation unit, respectively, and at least one of the first and second electrodes and the two output terminals of the AC power generation unit, The power receiving device is disposed at a predetermined distance, and a total width including the predetermined distance is not more than λ / 2π that is a near field. Third and fourth electrodes having the third A second inductor connected between the first electrode and the fourth electrode; a third and fourth connection line that electrically connects the third and fourth electrodes and the two input terminals of the load; 4 electrodes and a second capacitor inserted between at least one of the two input terminals of the load, and is constituted by the first and second electrodes, the first capacitor, and the first inductor. The coupler forms one resonance circuit, and the coupler constituted by the third and fourth electrodes, the second capacitor, and the second inductor forms another resonance circuit, and the first and second A resonance frequency of a coupler constituted by the electrode, the first capacitor, and the first inductor; the third and fourth electrodes; the second capacitor; and the second inductor. The first and second electrodes and the third and fourth electrodes are arranged at a distance of λ / 2π or less which is a near field. It is characterized by that.
According to such a configuration, it is possible to provide a wireless power transmission system that can transmit power efficiently.

In one aspect of the present invention, at least one of the first and second capacitors is an electrode provided to face at least one of the first and second electrodes, or the third and fourth electrodes. It has the electrode provided so that it might oppose at least one of these, It is characterized by the above-mentioned.
According to such a configuration, since the capacitor can be configured using the existing first and second electrodes or the third and fourth electrodes, the number of components can be reduced.

In one aspect of the present invention, the first and second electrodes are formed on a dielectric substrate, and the first capacitor faces at least one of the first and second electrodes with the dielectric substrate interposed therebetween. The third and fourth electrodes are formed on a dielectric substrate, and the second capacitor faces at least one of the third and fourth electrodes with the dielectric substrate interposed therebetween. It has the electrode arrange | positioned so that it may carry out.
According to such a configuration, since the capacitor can be configured using the dielectric substrate, the thickness of the device can be reduced.

In one aspect of the present invention, the first and second capacitors are constituted by chip capacitors.
According to such a configuration, the resonance frequency can be stabilized by using a chip capacitor having a stable element value.

In the power transmission device of the wireless power transmission system that wirelessly transmits AC power from the power transmission device to the power reception device, the present invention is arranged at a predetermined distance, and the total width including the predetermined distance is near First and second electrodes having a length of λ / 2π or less, which is a field, a first inductor connected between the first and second electrodes, the first and second electrodes, and an AC power generation unit First and second connection lines that electrically connect the two output terminals, respectively, and a first inserted between at least one of the first and second electrodes and the two output terminals of the AC power generation unit. A coupler constituted by a capacitor, the first and second electrodes, the first capacitor, and the first inductor forms a resonance circuit, and the third and fourth electrodes and the second of the power receiving device. Ki The coupler constituted by the capacitor and the second inductor forms another resonance circuit, and the resonance frequency of the coupler constituted by the first and second electrodes, the first capacitor, and the first inductor is: the power receiving device is set to be substantially equal to the resonant frequency of the coupler constituted by the said third and fourth electrodes and the second capacitor and the second inductor included in the said first and second electrode second The third and fourth electrodes are arranged with a distance of λ / 2π or less that is a near field.
According to such a configuration, it is possible to provide a power transmission device that can efficiently transmit power.

In the power receiving device of the wireless power transmission system that wirelessly transmits AC power from the power transmitting device to the power receiving device, the present invention is arranged at a predetermined distance, and the total width including the predetermined distance is near The third and fourth electrodes having a length equal to or less than λ / 2π, which is a field, a second inductor connected between the third and fourth electrodes, and two inputs of the third and fourth electrodes and a load And a third capacitor inserted electrically between at least one of the third and fourth electrodes and the two input terminals of the load. A coupler constituted by the first and second electrodes and the first capacitor and the first inductor included in the power transmission device forms one resonance circuit, and the third and fourth electrodes and the second capacitor; Above Coupler constituted by a second inductor to form another resonant circuit, the third and fourth electrodes and the second capacitor, the resonant frequency of the coupler constituted by the second inductor, the first And the second electrode, the first capacitor, and the first inductor are set to be substantially equal to the resonance frequency of the coupler, and the first and second electrodes and the third and fourth electrodes are in the vicinity. It is characterized by being arranged at a distance of λ / 2π or less which is a field.
According to such a configuration, it is possible to provide a power receiving device that can efficiently transmit power.

  According to the present invention, it is possible to provide a wireless power transmission system, a power transmission device, and a power reception device that can efficiently transmit power.

It is a figure for demonstrating the operation principle of the wireless power transmission system using a series resonance. It is an equivalent circuit of the structure 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 detailed structural example of the power transmission apparatus which comprises the wireless power transmission system using a series resonance. It is a figure which shows the structural example of the wireless power transmission system using a series resonance. FIG. 6 is a diagram illustrating frequency characteristics of transmission efficiency and reflection loss of the wireless power transmission system illustrated in FIG. 5. It is a figure which shows the frequency characteristic of the input impedance of the wireless power transmission system shown in FIG. It is a figure which shows the detailed structural example of the power transmission coupler which comprises the wireless power transmission system using a parallel resonance. FIG. 9 is an equivalent circuit having the configuration shown in FIG. 8. FIG. FIG. 9 is a diagram illustrating frequency characteristics of transmission efficiency and reflection loss of the wireless power transmission system illustrated in FIG. 8. It is a figure which shows the frequency characteristic of the input impedance of the wireless power transmission system shown in FIG. It is a figure which shows the detailed structural example of the power transmission coupler which comprises the wireless power transmission system using a parallel resonance. It is a figure which shows the frequency characteristic of the transmission efficiency and reflection loss of the wireless power transmission system shown in FIG. It is a figure which shows the frequency characteristic of the input impedance of the wireless power transmission system shown in FIG. It is a figure which shows the structural example of the power transmission coupler which concerns on 1st Embodiment of this invention. It is a figure which shows the structural example of the wireless power transmission system which concerns on 1st Embodiment of this invention. It is an equivalent circuit of 1st Embodiment shown in FIG. It is a figure which shows the frequency characteristic of the transmission efficiency and reflection loss of 1st Embodiment shown in FIG. It is a figure which shows the frequency characteristic of the input impedance of 1st Embodiment shown in FIG. It is a figure which shows the structural example of the wireless power transmission system which concerns on 2nd Embodiment of this invention. It is a figure which shows the frequency characteristic of the transmission efficiency and reflection loss of 2nd Embodiment shown in FIG. It is a figure which shows the frequency characteristic of the input impedance of 2nd Embodiment shown in FIG.

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

(A) Description of Operation Principle of Embodiment The present embodiment is characterized in that power is transmitted by generating a resonance point lower than the parallel resonance point by adding a capacitor. After describing the configuration for transmitting power using series resonance, this embodiment will be described.

  FIG. 1 is a diagram for explaining an operation principle of a wireless power transmission system 1 using series resonance. As shown in this figure, the wireless 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 wireless power transmission system 1 shown in FIG. In FIG. 2, the power source load 222 has a value equal to the characteristic impedance of the connection lines 15 and 16 and the connection lines 25 and 26, and has a value of Z0. The resistor 2 indicates a resistor associated with the power transmission side circuit, mainly the inductor, and has an element value of R1. The inductor 3 corresponds to the inductors 13 and 14 and has an element value of L1. The capacitor 4 is a capacitor having an element value C 1 generated between the electrodes 11 and 12. The capacitor 6 is a capacitor having an element value C 2 generated between the electrodes 21 and 22. The capacitor 5 is a capacitor generated between the electrodes 11 and 12 and the electrodes 21 and 22, and has an element value of Cm. The inductor 7 corresponds to the inductors 23 and 24 and has an element value of L2. The resistor 8 indicates a resistor associated with the power receiving side circuit, mainly the inductor, and has an element value of R2.

FIG. 3 shows the frequency characteristics of the S parameter between the power transmission device 10 and the power reception device 20. 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 anti-resonance point at the frequency f _C and has resonance points at the frequencies f _L and f _H. Here, the frequency f _C is determined by the inductance values L 1 and L 2 of the inductors 3 and 7 shown in FIG. 2 and the capacitance values C 1 and C 2 of the capacitors 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 values L 1 and L 2 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 And capacitance values C1 and C2 of the capacitors generated between the electrodes 21 and 22, respectively.

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 wireless power transmission system 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 coupled by electric field resonance, and the electrodes 11 and 12 of the power transmission device 10 are connected to the electrodes of the power reception device 20. AC power is transmitted to 21 and 22 by an electric field.

  That is, in the wireless power transmission system 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 with a distance d2 shorter than λ / 2π that is the near field. Therefore, 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.

  FIG. 4 shows a detailed configuration example of a power transmission coupler constituting a wireless power transmission system using series resonance. As shown in this figure, in a wireless power transmission system using series resonance, a power transmission coupler 110 is a table (mainly) of a circuit board 118 formed of an insulating member (dielectric substrate) having a rectangular plate shape. The electrodes 111 and 112 made of a conductive member having a rectangular shape are arranged on the surface 118A. 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. .

  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. The inductors 113, 114, 123, and 124 of the power transmission coupler 110 and the power reception coupler 120 each have 13 turns and an inductance value of 2.8 μH at f _C.

  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.

  Next, the operation of the wireless power transmission system using the series resonance shown in FIG. 5 will be described. FIG. 6 illustrates transmission from the power transmission coupler 110 to the power reception coupler 120 when the power transmission coupler 110 and the power reception coupler 120 of the wireless power transmission system illustrated in FIG. 5 are arranged to face each other with a distance of 20 cm (d2 = 20 cm). It is a figure which shows the frequency characteristic of efficiency (eta) 21 (= | S21 | ^ 2) and reflection loss (eta) 11 (= | S11 | ^ 2). In this figure, the horizontal axis indicates the frequency (MHz) of AC power to be transmitted, and the vertical axis indicates transmission efficiency. In the example shown in FIG. 6, it can be seen that a transmission efficiency of 90% or more is achieved around 27 MHz. In FIG. 5, for example, the inductors 113, 114, 123, and 124 each have 13 turns and an inductance value of 2.8 μH, and the circuit boards 118 and 128 have a size (D and L) of 250 ×. The gap d1 between the electrodes 111 and 112 and the electrodes 121 and 122 is 34.4 mm.

  FIG. 7 is a diagram showing the input impedance characteristics of the wireless power transmission system using the series resonance shown in FIG. As shown in FIG. 7, the real part Re of the input impedance is about 50Ω near the resonance frequency of 27 MHz, and the imaginary part Im is about 0Ω.

  Next, a case where parallel resonance is performed will be described with reference to FIG. In FIG. 8, one end of inductors 113 and 114 is connected to one end of the electrodes 111 and 112 of the circuit board 118 constituting the power transmission coupler 110A in the short direction. The other ends of the inductors 113 and 114 are connected to each other. One end of each of the connection lines 115 and 116 is directly connected to the other end portion of the electrodes 111 and 112 in the short direction. The power receiving coupler 120A has the same configuration as that of the power transmitting coupler 110A, and these power transmitting coupler 110A and power receiving coupler 120A are arranged to face each other with a certain distance as in FIG. In FIG. 8, the inductors 113 and 114 each have 13 turns and an inductance value of 2.8 μH. The resistance value associated with each inductor at this time is 0.5Ω.

  FIG. 9 is a diagram showing an equivalent circuit of a wireless power transmission system including the power transmission coupler 110A shown in FIG. 8 and a power reception coupler 120A (not shown) having the same configuration. 9, parts corresponding to those in FIG. 2 are given the same reference numerals and explanation thereof is omitted. In the equivalent circuit shown in FIG. 9, the resistor 2 and the inductor 3, the resistor 8 and the inductor 7 are connected in series, and the capacitor 4 and the capacitor 6 are connected in parallel, respectively, as compared with FIG. 2. The other configuration is the same as that of FIG.

  FIG. 10 shows the transmission efficiency η21 (= | S21 | ^ 2) from the power transmission coupler 110A to the power reception coupler 120A when the power transmission coupler 110A and the power reception coupler 120A shown in FIG. It is a figure which shows the frequency characteristic of reflection loss (eta) 11 (= | S11 | ^ 2). In FIG. 10, for example, each of the inductors 113, 114, 123, and 124 has 13 turns and an inductance value of 2.8 μH, and the circuit boards 118 and 128 have a size (D and L) of 250 ×. The gap d1 between the electrodes 111 and 112 and the electrodes 121 and 122 is 34.4 mm. As shown in this figure, the transmission efficiency η21 is 0% regardless of the frequency, and the reflection loss η11 is “1” regardless of the frequency.

  FIG. 11 is a diagram showing the input impedance characteristics when the power transmitting coupler 110A shown in FIG. 8 and a power receiving coupler 120A (not shown) are arranged to face each other with a distance of 20 cm. As shown in FIG. 11, the real part Re of the input impedance is about 20 kΩ or more near the resonance frequency of 27 MHz, and the imaginary part Im changes from plus infinity to minus infinity around 27 MHz. That is, it is anti-resonant at the resonance frequency. From the above, the wireless power transmission system using the power transmission coupler 110A cannot transmit power.

  FIG. 12 shows a configuration in which the inductors 113 and 114 of the power transmission coupler 110A shown in FIG. 8 are replaced with inductors 113A and 114A having low inductance values. In FIG. 12, each of the inductors 113A and 114A has 8 turns and an inductance value of 1.72 μH.

  FIG. 13 shows a transmission efficiency η21 (= 21) from the power transmission coupler 110B to the power reception coupler 120B when the power transmission coupler 110B shown in FIG. 12 and the power reception coupler 120B having the same configuration are arranged 20 cm apart from each other. It is a figure which shows the frequency characteristic of | S21 | ^ 2) and reflection loss η11 (= | S11 | ^ 2). As shown in this figure, the transmission efficiency η21 is 0% regardless of the frequency, and the reflection loss η11 is “1” regardless of the frequency.

  FIG. 14 is a diagram illustrating input impedance characteristics of a wireless power transmission system using the power transmission coupler 110B illustrated in FIG. 12 and the power reception coupler 120B having the same configuration as that of FIG. Compared to FIG. 11, in FIG. 14, the antiresonance frequency is increased from about 27 MHz to about 38 MHz. Further, the real part Re of the input impedance is about 20 kΩ or more near the resonance frequency of about 38 MHz, and the imaginary part Im changes from plus infinity to minus infinity at around 38 MHz. In FIG. 14 as well, anti-resonance occurs at the resonance frequency. From the above, the wireless power transmission system using the power transmission coupler 110B cannot transmit power.

(B) Description of First Embodiment Next, a wireless power transmission system according to the first embodiment of the present invention will be described. FIG. 15 is a diagram illustrating a configuration example of a power transmission coupler 110C of the wireless power transmission system according to the first embodiment of the present invention. In this figure, parts corresponding to those in FIG. 15, chip capacitors 311 and 312 are inserted between the electrodes 111 and 112 and the connection lines 115 and 116, respectively, as compared to FIG. The chip capacitor 311 has one terminal connected to one end of the connection line 115 and the other terminal connected to the electrode 111. The chip capacitor 312 has one terminal connected to one end of the connection line 116 and the other terminal connected to the electrode 112. Other configurations are the same as those in FIG. The power receiving coupler 120C is configured similarly to the power transmitting coupler 110C.

  FIG. 16 is a diagram illustrating a configuration example of a wireless power transmission system using the power transmission coupler 110C and the power reception coupler 120C illustrated in FIG. In the example of this figure, the power transmission coupler 110C and the power reception coupler 120C are disposed to face each other with a distance of 20 cm. The inductors 113A, 114A, 123A, and 124A each have eight turns and an inductance value of 1.72 μH. The resistance value associated with each inductor at this time is 0.3Ω. The element values of the chip capacitors 311, 312, 411, and 412 are 10.4 pF, respectively.

  FIG. 17 is a diagram illustrating an equivalent circuit of the wireless power transmission system illustrated in FIG. 16. In FIG. 17, the same reference numerals are given to the portions corresponding to those in FIG. Compared with FIG. 9, FIG. 17 shows that the capacitors 500 corresponding to the chip capacitors 311 and 312 are inserted between the AC power generation unit 17 and the inductor 3 and the resistor 2, respectively, and between the load 27 and the inductor 7 and the resistor 8. Capacitors 501 corresponding to the chip capacitors 411 and 412 are respectively inserted. Other configurations are the same as those in FIG. In the wireless power transmission system shown in FIG. 16, by adding the chip capacitors 311, 312, 411, 412 in series, a series resonance circumference is generated at a frequency lower than the parallel resonance frequency of the equivalent circuit shown in FIG. That is, the resonance frequency can be lowered. Since the input impedance also changes due to the addition of the chip capacitor, matching can be achieved to, for example, 50Ω at the resonance frequency by properly combining the element values of the inductor and the chip capacitor.

  FIG. 18 shows a transmission efficiency η21 (= | S21 |) from the power transmission coupler 110D to the power reception coupler 120D when the power transmission coupler 110C and the power reception coupler 120C of the wireless power transmission system shown in FIG. It is a figure which shows the frequency characteristic of (^ 2) and reflection loss (eta) 11 (= | S11 | ^ 2). In this example, each of the inductors 113, 114, 123, and 124 has eight turns and an inductance value of 1.72 μH, and the resistance value associated with each inductor at this time is 0.3Ω. The sizes (D and L) of the circuit boards 118 and 128 are 250 × 250 mm, and the gap d1 between the electrodes 111 and 112 and the electrodes 121 and 122 is 34.4 mm. As shown in this figure, the transmission efficiency η21 of the wireless power transmission system shown in FIG. 17 is 90% or more at about 27 MHz, and the reflection loss η11 is 0 at about 27 MHz.

  FIG. 19 is a diagram showing the input impedance characteristics of the wireless power transmission system shown in FIG. As shown in FIG. 19, the real part Re of the input impedance is 50Ω at about 27 MHz, and the imaginary part is 0Ω at about 27 MHz. In addition, compared with the characteristic of FIG. 12 (refer FIG. 14) using the same inductor, the resonant frequency has fallen from 38 MHz to 27 MHz.

  As described above, in the wireless power transmission system according to the first embodiment of the present invention, by connecting chip capacitors in series, an element value as an inductor can be obtained even at the same resonance frequency as compared with the configuration shown in FIG. Since a small device can be used, the size of the device can be reduced. Even when an inductor having a small element value is used, the transmission efficiency can be kept high.

(C) Description of Second Embodiment Next, a wireless power transmission system according to a second embodiment of the present invention will be described. FIG. 20 is a diagram illustrating a configuration example of a wireless power transmission system according to the second embodiment of the present invention. In this figure, portions corresponding to those in FIG. 16 are denoted by the same reference numerals and description thereof is omitted. In FIG. 20, compared with FIG. 16, the chip capacitors are excluded, and instead, capacitors using circuit boards 118 and 128 are arranged. More specifically, in the example of FIG. 20, capacitor electrodes 711 and 712 are formed on the back surface 128 </ b> B of the circuit board 128 by a conductive member having a rectangular shape at a position facing a part of the electrodes 121 and 122. A capacitor is formed between the electrodes 211 and 212 formed on the surface 128 </ b> A of the circuit board 128. The capacitor electrodes 711 and 712 are connected to connection lines 125 and 126. On the back surface 119B of the circuit board 118, capacitor electrodes 611 and 612 are formed by a conductive member having a rectangular shape at a position facing a part of the electrodes 111 and 112, and are formed on the front surface 118A of the circuit board 118. A capacitor is formed between the electrodes 111 and 112. The capacitor electrodes 611 and 612 are connected to the connection lines 115 and 116.

  In the second embodiment shown in FIG. 20, the power transmission coupler 110D and the power reception coupler 120D are arranged to face each other with a distance of 20 cm. The inductors 113A, 114A, 123A, and 124A each have eight turns and an inductance value of 1.72 μH. The resistance value associated with each inductor at this time is 0.3Ω. Also, the capacitor element values of the capacitor electrodes 611 and 612 and the electrodes 111 and 112 are set so that the resonance frequency is about 28 MHz, and the capacitor element values of the capacitor electrodes 711 and 712 and the electrodes 121 and 122 are also about the resonance frequency. It is set to be 28 MHz. The equivalent circuit of the second embodiment shown in FIG. 20 is the same as that of FIG.

  FIG. 21 shows the transmission efficiency η21 (= | S21 |) from the power transmission coupler 110D to the power reception coupler 120D when the power transmission coupler 110D and the power reception coupler 120D of the wireless power transmission system shown in FIG. It is a figure which shows the frequency characteristic of (^ 2) and reflection loss (eta) 11 (= | S11 | ^ 2). In this example, each of the inductors 113, 114, 123, and 124 has eight turns and an inductance value of 1.72 μH. The resistance value associated with each inductor at this time is 0.3Ω. The sizes (D and L) of the circuit boards 118 and 128 are 250 × 250 mm, and the gap d1 between the electrodes 111 and 112 and the electrodes 121 and 122 is 34.4 mm. As shown in this figure, the transmission efficiency η21 is 90% or more at about 28 MHz, and the reflection loss η11 is 0 at about 28 MHz.

  FIG. 22 is a diagram illustrating the input impedance characteristics of the wireless power transmission system using the power transmission coupler 110D and the power reception coupler 120D illustrated in FIG. As shown in FIG. 22, the real part Re of the input impedance is 50Ω at about 28 MHz, and the imaginary part is 0Ω at about 28 MHz.

  As described above, in the wireless power transmission system according to the second embodiment of the present invention, by connecting capacitors in series, the element value is small as an inductor even at the same resonance frequency compared to the configuration shown in FIG. Since it becomes possible to use a thing, the size of an apparatus can be reduced in size.

  Further, in the second embodiment, compared to the first embodiment, the capacitor can be configured using the circuit boards 118 and 128, so that the number of parts can be reduced.

(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 each of the above embodiments, the electrodes 111 and 112 and the electrodes 121 and 122 have the same size, but they may have different sizes. Specifically, the electrodes 121 and 122 may be smaller in size than the electrodes 111 and 112. Of course, the reverse configuration may be used.

  Further, in the above embodiment, the electrodes 111 and 112 and the electrodes 121 and 122 are arranged to face each other. For example, they are arranged so as to be shifted in the X direction or the Y direction shown in FIG. Also good. Alternatively, the power transmission coupler 110 and the power reception coupler 120 may be arranged so as to relatively rotate by a predetermined angle.

  Further, the shapes of the electrodes 111 and 112 and the electrodes 121 and 122 may be circular or elliptical instead of rectangular. 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.

  Moreover, although the inductors 113 and 114 and the inductors 123 and 124 are configured to connect two inductors, they may be configured as one. 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 first embodiment, a chip capacitor is used, and in the second embodiment, a capacitor using a circuit board as a dielectric is used. However, a chip capacitor and a capacitor using a circuit board as a dielectric are used in combination. Also good. For example, only one of the power transmission coupler and the power reception coupler may be a chip capacitor, and the other may be a capacitor using a circuit board. Of course, a chip capacitor and a capacitor using a circuit board may be used in combination for each of the power transmission coupler and the power reception coupler.

DESCRIPTION OF SYMBOLS 1 Wireless power transmission system 10 Power transmission apparatus 11,12 Electrode 13,14 Inductor 15,16 Connection line 17 AC power generation part 20 Power reception apparatus 21,22 Electrode 23,24 Inductor 25,26 Connection line 27 Load 110 Transmission coupler 111, 112 electrodes (first electrode, second electrode)
113A, 114A inductor (first inductor)
115, 116 connection line (first connection line, second connection line)
118 circuit board 120 power receiving coupler 121, 122 electrode (third electrode, fourth electrode)
123A, 124A inductor (second inductor)
125, 126 connection lines (third connection line, fourth connection line)
128 Circuit board 222 Power supply load 311, 312 Chip capacitor (first capacitor)
411, 412 Chip capacitor (second capacitor)
611,612 Capacitor electrode (first capacitor)
711,712 capacitor electrode (second capacitor)

Claims (6)

In a wireless power transmission system that transmits AC power wirelessly from a power transmitting device to a power receiving 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 inductor connected between the first and second electrodes;
First and second connection lines that electrically connect the first and second electrodes and the two output terminals of the AC power generation unit, respectively;
A first capacitor inserted between the first and second electrodes and at least one of the two output terminals of the AC power generation unit;
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 inductor connected between the third and fourth electrodes;
Third and fourth connection lines that electrically connect the third and fourth electrodes and the two input terminals of the load, respectively;
A second capacitor inserted between the third and fourth electrodes and at least one of the two input terminals of the load;
A coupler constituted by the first and second electrodes, the first capacitor, and the first inductor forms one resonance circuit, and the third and fourth electrodes, the second capacitor, and the second capacitor. A coupler composed of an inductor forms another resonant circuit,
Resonant frequency of a coupler constituted by the first and second electrodes and the first capacitor and the first inductor, and constituted by the third and fourth electrodes and the second capacitor and the second inductor. And the first and second electrodes and the third and fourth electrodes are arranged at a distance of λ / 2π or less which is a near field.
A wireless power transmission system.   At least one of the first and second capacitors is provided to face at least one of the first and second electrodes or at least one of the third and fourth electrodes. The wireless power transmission system according to claim 1, further comprising: a plurality of electrodes. The first and second electrodes are formed on a dielectric substrate, and the first capacitor has an electrode arranged to face at least one of the first and second electrodes with the dielectric substrate interposed therebetween. ,
The third and fourth electrodes are formed on a dielectric substrate, and the second capacitor has an electrode disposed so as to face at least one of the third and fourth electrodes with the dielectric substrate interposed therebetween.
The wireless power transmission system according to claim 2.   The wireless power transmission system according to claim 1, wherein at least one of the first and second capacitors is configured by a chip capacitor. In the power transmission device of the wireless power transmission system that wirelessly transmits AC power from the power transmission device to the power reception device,
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 inductor connected between the first and second electrodes;
First and second connection lines that electrically connect the first and second electrodes and the two output terminals of the AC power generation unit, respectively;
A first capacitor inserted between at least one of the first and second electrodes and the two output terminals of the AC power generation unit;
A coupler constituted by the first and second electrodes and the first capacitor and the first inductor forms one resonance circuit, and the third and fourth electrodes and the second capacitor of the power receiving device, A coupler constituted by the second inductor forms another resonance circuit,
Said first and second electrode and the first capacitor, the resonant frequency of the coupler constituted by the first inductor, the power receiving apparatus wherein the second and the third and fourth electrodes and the second capacitor having the The first and second electrodes and the third and fourth electrodes are arranged at a distance of λ / 2π or less that is a near field. The
A power transmission device characterized by that. In the power receiving device of the wireless power transmission system that wirelessly transmits AC power from the power transmitting device to the power receiving device,
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 inductor connected between the third and fourth electrodes;
Third and fourth connection lines that electrically connect the third and fourth electrodes and the two input terminals of the load, respectively;
A second capacitor inserted between the third and fourth electrodes and at least one of the two input terminals of the load;
A coupler constituted by the first and second electrodes and the first capacitor and the first inductor included in the power transmission device forms one resonance circuit, and the third and fourth electrodes and the second capacitor, A coupler constituted by the second inductor forms another resonance circuit,
Configuration and said third and fourth electrodes and the second capacitor, the resonant frequency of the coupler constituted by the second inductor, said first and second electrode and the first capacitor, the said first inductor The first and second electrodes and the third and fourth electrodes are arranged at a distance of λ / 2π or less, which is a near field.
A power receiving device.

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