JP2014003774A - Mobile wireless power receiving apparatus and wireless power transmission system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile wireless power receiving apparatus that can facilitate such impedance matching as reduces reflection on a transmission line by a receiver.SOLUTION: A mobile wireless power receiving apparatus 3 includes: a resonant receiver 4 to be electromagnetically coupled with a transmission line 20 for transmitting high frequency power from one end 20a to the other end 20b; an impedance matching circuit 6 connected between an output side of the receiver 4 and a load 5 to perform impedance matching; and a resonant reflector 7 to be electromagnetically coupled with the transmission line 20 at a side nearer to the other end 20b of the transmission line 20 than the receiver 4. For reducing reflection on the transmission line 20 by the receiver 4, the reflector 7 reflects oncoming high frequency power to generate a reflected wave heading to the one end 20a on the transmission line 20, and the receiver 4 absorbs the reflected wave and outputs it to the impedance matching circuit 6.

Description

  The present invention relates to a mobile wireless power receiving apparatus that can receive power from a power receiver that moves power from a transmission line constituting the wireless power transmitting apparatus, and a wireless power transmission system using the mobile wireless power receiving apparatus.

  Various types of wireless power transmission systems that wirelessly transmit power from a wireless power transmission device to a power receiver are known. Among these, the method in which the power of the wireless power transmission device is transmitted according to the coupling with the receiver using non-radiating electromagnetic field coupling can be obtained in recent years, Has attracted a lot of attention. Among these, a wireless power transmission system capable of transmitting power from a wireless power transmission device to a moving power receiver is also known.

  For example, in Patent Document 1, a wireless power transmission device is configured by arranging a large number of power transmission side resonators in which metal conductors are wound in a coil shape along a path of an automobile including a power reception device including a power reception side resonator. However, there is a description that supplies power from the wireless power transmission apparatus to the battery of the automobile through the power receiver.

  While such a power transmission device tends to be large as equipment, Patent Document 2 discloses that a wireless power transmission device is configured by a transmission line that extends in a straight line, and is electromagnetically placed over the transmission line. What is provided with a power receiver that is coupled and supplied with power is described. The thing of patent document 2 is easy to install as infrastructure, since it does not become so large as an installation.

US Patent No. 8030888 JP 2011-72176 A

  However, the structure described in Patent Document 2 is currently being studied for practical use, and there is still room for further improvement. For example, when the power receiver moves to a transmission line in an impedance matching state, impedance mismatch occurs by the power receiver, reflection occurs on the transmission line, and transmission efficiency may be reduced. In such cases, practical measures are required.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a mobile wireless power receiving apparatus that can easily perform impedance matching so as to reduce reflection that occurs on a transmission line by a power receiver, and to use the same. It is to provide a wireless power transmission system.

  In order to achieve the above object, a mobile wireless power receiving device according to claim 1 is a resonance type power receiver that is electromagnetically coupled to a transmission line that transmits high frequency power from one end to the other end, and the power receiver. An impedance matching circuit connected between the output side and the load for impedance matching, and a resonant reflector that electromagnetically couples to the transmission line on the other end side of the transmission line with respect to the power receiver. Comprising, to reduce the reflection that occurs on the transmission line by the power receiver, the high-frequency power that the reflector has reached is reflected to generate a reflected wave toward the one end side on the transmission line, The power receiver absorbs the reflected wave and outputs it to the impedance matching circuit.

  The mobile wireless power receiving device according to claim 2 is the mobile wireless power receiving device according to claim 1, wherein the power receiver is resonated at a half wavelength of the high-frequency power to obtain a quadrant of the high-frequency power. The transmission line is electromagnetically coupled to the transmission line at one wavelength.

  The mobile wireless power receiving device according to claim 3 is the mobile wireless power receiving device according to claim 1 or 2, wherein the reflector resonates at a half wavelength of the high frequency power, The transmission line is electromagnetically coupled to the transmission line at a quarter wavelength.

  The mobile wireless power receiving device according to claim 4 is the mobile wireless power receiving device according to any one of claims 1 to 3, wherein the power receiver is electromagnetically coupled to the transmission line, and The position interval of the portion where the reflector is electromagnetically coupled to the transmission line is an odd multiple of a quarter wavelength of the high frequency power.

  The mobile wireless power receiving device according to claim 5 is the mobile wireless power receiving device according to any one of claims 1 to 4, wherein the impedance matching circuit includes a variable impedance element, and the impedance The impedance of the variable element can be changed in accordance with the change in the output impedance of the power receiver.

  A wireless power transmission system according to claim 6 is connected to the mobile wireless power receiving device according to any one of claims 1 to 5, the transmission line, a high-frequency power source connected to one end thereof, and the other end. And a wireless power transmission device having a non-reflective terminal.

  The wireless power transmission system according to claim 7 is the wireless power transmission system according to claim 6, wherein the transmission line is a microstrip line.

  According to the present invention, by using an impedance matching circuit and a reflector, a mobile wireless power receiving apparatus that can easily perform impedance matching so as to reduce reflection that occurs on the transmission line by the power receiver, and the same are used. A wireless power transmission system can be provided.

It is a schematic diagram which shows the structure of the wireless power transmission system which concerns on embodiment of this invention. It is a top view which shows the structure of the principal part of a wireless power transmission system same as the above. It is sectional drawing cut | disconnected by the XX plane of the wireless power transmission system same as the above. It is a perspective view which shows the structure of the principal part of a wireless power transmission system same as the above. It is a circuit example of the impedance matching circuit of a mobile type | mold wireless power receiving device same as the above. It is a characteristic figure of the simulation experiment which shows the reference characteristic of S parameter of a wireless power transmission system same as the above. It is a characteristic view of the simulation experiment which shows the characteristic of S parameter of a wireless power transmission system same as the above. It is a characteristic view of the simulation experiment which shows the characteristic of S33 among S parameters of a wireless power transmission system same as the above. It is a characteristic view of the sample experiment which shows the characteristic of S parameter of a wireless power transmission system same as the above. It is a characteristic figure of the simulation experiment which shows the reference characteristic of S parameter when deform | transforming the wireless power transmission system same as the above.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. A wireless power transmission system 1 according to an embodiment of the present invention includes a wireless power transmission device 2 and a mobile wireless power reception device 3 as shown in FIG.

  The wireless power transmission device 2 includes a transmission line 20, a high frequency power source 21 connected to one end 20a thereof, and a non-reflective terminal 22 connected to the other end 20b. The transmission line 20 sends high-frequency power from one end 20a to the other end 20b, and extends one-dimensionally in a straight line direction or a curve direction with a slight curvature.

  More specifically, the transmission line 20 may be a microstrip line that extends long as shown in FIG. The transmission line 20 using the microstrip line is formed on (or embedded in) the insulating material 20 ′ as shown in FIG. 3, and the ground line 20 is formed on the opposite side of the insulating material 20 ′ in the thickness direction. '' Is formed. In FIG. 2, a part of the transmission line 20 using a microstrip line is shown, and a part having a slight curvature is shown. Further, FIG. 3 shows the enlarged thickness direction for easy understanding.

  The high frequency power source 21 generates high frequency power and outputs it to the one end 20 a of the transmission line 20. In addition, the non-reflective terminal 22 has the other end 20b of the transmission line 20 grounded through a predetermined impedance. The non-reflective termination 22 is, for example, a 50Ω termination resistor.

  The mobile wireless power receiving device 3 includes a resonance type power receiver 4 that is electromagnetically coupled to the transmission line 20 of the wireless power power transmitting device 2, and an impedance matching circuit that is connected between the output side of the power receiver 4 and the load 5. 6 and a resonance type reflector 7 electromagnetically coupled to the transmission line 20 on the other end 20b side of the transmission line 20 relative to the power receiver 4. The load 5 is a circuit such as a battery for a vehicle or the like to perform a required function.

  The power receiver 4 is movable along the transmission line 20. High frequency power of the transmission line 20 is transmitted to the power receiver 4. In other words, the power receiver 4 absorbs the high frequency power of the transmission line 20. The absorbed high frequency power resonates at the power receiver 4 and is output to the impedance matching circuit 6.

  The power receiver 4 preferably resonates at a half wavelength of the high frequency power and is electromagnetically coupled to the transmission line 20 at a quarter wavelength of the high frequency power. For example, as shown in FIG. 2, the power receiver 4 is formed of a bent strip conductor, and the total length is approximately equal to one-half wavelength of the high-frequency power so as to resonate at one-half wavelength of the high-frequency power. Then, one side is set as an electromagnetic field coupling portion (a portion where the power receiver 4 is electromagnetically coupled to the transmission line 20) 40 and has a length substantially equal to a quarter wavelength of the high frequency power. Then, as shown in FIG. 4, when the electromagnetic coupling portion 40 is overlapped with a gap in the transmission line 20 of the microstrip line, the high frequency power of the transmission line 20 is properly transmitted to the power receiver 4. The high frequency power resonates at the power receiver 4. In this way, the power receiver 4 is small and can absorb the high-frequency power of the transmission line 20 with high efficiency.

  In FIG. 2, the power receiver 4 formed of a strip conductor shows that the electromagnetic field coupling portion 40 has a slight curvature, and is substantially perpendicular to the electromagnetic field coupling portion 40. And a portion 42 that is formed substantially perpendicularly from the tip of the portion 41. As shown in FIG. 3, the power receiver 4 is formed on (or embedded in) the insulating material 4 ′, and a grounding line 4 ″ is formed on the opposite side of the insulating material 4 ′ in the thickness direction. Can be done.

  The impedance matching circuit 6 is connected to the output side of the power receiver 4 to prevent reflection due to impedance mismatch. The impedance matching circuit 6 can be a lumped constant circuit combining an inductor and a capacitor, and can be easily adapted to the positional relationship between the electromagnetic coupling portion 40 of the power receiver 4 and the transmission line 20, the shape of the power receiver 4, and the like. Impedance can be matched. As the impedance matching circuit 6, for example, a π-type circuit including a capacitor 61, an inductor 62, and a capacitor 63 as shown in FIG. Alternatively, a T-type circuit can be used.

  The reflector 7 reflects the high frequency power transmitted from the one end 20a of the transmission line 20 toward the other end 20b, and generates a reflected wave on the transmission line 20 toward the one end 20a side. The reflector 7 can also reflect almost all of the high-frequency power on the transmission line 20 that has reached that position.

  The reflector 7 preferably resonates at a half wavelength of the high frequency power and is electromagnetically coupled to the transmission line 20 at a quarter wavelength of the high frequency power. For example, as shown in FIG. 2, the reflector 7 is formed of a bent strip conductor, and the total length is approximately equal to one-half wavelength of the high-frequency power so as to resonate at one-half wavelength of the high-frequency power. Then, one side thereof is set as an electromagnetic field coupling portion (a portion where the reflector 7 is electromagnetically coupled to the transmission line 20) 70 and has a length substantially equal to a quarter wavelength of the high frequency power. Then, as shown in FIG. 4, when the electromagnetic coupling portion 70 is overlapped with a gap in the transmission line 20 of the microstrip line, the reflector 7 that resonates with the high frequency power of the transmission line 20 that has reached that position. Is reflected by. Such a reflector 7 is small and can reflect with high efficiency.

  In FIG. 2, the reflector 7 formed of a strip conductor shows that the electromagnetic field coupling portion 70 has a slight curvature, and is substantially perpendicular to the electromagnetic field coupling portion 70. And a portion 72 formed substantially perpendicularly from the tip of the portion 71 is shown. In addition, the reflector 7 normally moves together with the power receiver 4 and is integrally formed so that the positional relationship with the power receiver 4 is not shifted. Therefore, similarly to the power receiver 4 shown in FIG. The ground line 4 '' can be formed on (or embedded in) the opposite side of the insulating material 4 'in the thickness direction.

  With such a configuration, in the wireless power transmission system 1, the reflector 7 reflects almost all of the high-frequency power on the transmission line 20 that reaches the position, and the receiver 4 absorbs almost all of the reflected wave. When output to the impedance matching circuit 6, the non-reflective terminal 22 connected to the other end 20 b of the transmission line 20 is not affected by the one end 20 a of the transmission line 20 relative to the reflector 7. Then, by causing the impedance matching circuit 6 to perform impedance matching, reflection that occurs on the transmission line 20 (a reflected wave that returns from the position of the power receiver 4 to the one end 20a side on the transmission line 20) can be reduced. As a result, it is possible to prevent a decrease in transmission efficiency from the transmission line 20 to the power receiver 4 due to impedance mismatch.

  When the moving mobile wireless power receiving apparatus 3 is located at a place other than the transmission line 20, the power receiver 4 and the reflector 7 are not electromagnetically coupled to the transmission line 20, and therefore the transmission line 20 has the other end 20b. Impedance matching is achieved by the non-reflective terminal 22 connected to.

  The position interval between the electromagnetic field coupling portion 40 of the power receiver 4 and the electromagnetic field coupling portion 70 of the reflector 7 is preferably an odd multiple of a quarter wavelength of the high frequency power. In this way, since the antinode of the standing wave is formed at the position of the electromagnetic field coupling portion 40 of the power receiver 4 in the transmission line 20, the transmission efficiency from the transmission line 20 to the power receiver 4 can be further increased.

  The wireless power transmission system 1 is configured such that an electric vehicle, a train, a transport robot in a factory, etc. has a battery as a load and a mobile wireless power receiving device 3, and the transmission line 20 is fixed where it passes. If so, the battery can be charged while moving.

  When the mobile wireless power receiving apparatus 3 moves, the electromagnetic field coupling portion 40 of the power receiver 4 increases or decreases in the gap with the transmission line 20 or the overlap with the transmission line 20 shifts, so that the power receiver 4 output impedance often changes. The impedance matching circuit 6 includes a variable impedance element so as to perform impedance matching corresponding thereto, and the impedance of the variable impedance element changes automatically or manually according to the change in the output impedance of the power receiver 4. Preferably it is possible. For example, the inductor 62 in FIG. 5 can be a variable impedance element.

  Next, simulations and sample experiments by the inventors will be described. In the wireless power transmission system 1 used in this experiment, the transmission line 20, the electromagnetic coupling portion 40 of the power receiver 4, and the electromagnetic coupling portion 70 of the reflector 7 have a slight curvature (see FIG. 2). reference). The width A of the transmission line 20, the width B of the power receiver 4, and the width C of the reflector 7 are almost 3.2 mm except for the bent portion. The length D of the electromagnetic field coupling portion 40 of the power receiver 4 is 23.84 mm, the length E of the portion 41 formed substantially perpendicular to the electromagnetic field coupling portion 40 is 6.59 mm, and the distal end portion of the portion 41 The length F of the portion 42 formed substantially perpendicular to the vertical axis is 5.98 mm. The length G of the electromagnetic field coupling portion 70 of the reflector 7 is 25.29 mm, the length H of the portion 71 formed substantially perpendicular to the electromagnetic field coupling portion 70 is 6.59 mm, and the tip of the portion 71 The length I of the portion 72 formed substantially perpendicular to is set to 3.97 mm. The distance J between the power receiver 4 and the reflector 7 is 22 mm. The thickness K of the transmission line 20 and the thickness L of the power receiver 4 are 15 μm, and the distance M between the insulating material 20 ′ where the transmission line 20 is formed and the insulating material 4 ′ where the power receiver 4 is formed is 1. 5 mm (see FIG. 3).

  6 to 8 are characteristic diagrams of the simulation experiment. FIG. 6 shows the characteristics of the S parameter when the impedance matching circuit 6 is omitted. FIG. 7 shows the characteristics of the S parameter when the impedance matching circuit 6 performs impedance matching. Of the S parameters, S11 is the ratio of high-frequency power that is returned (reflected) to the one end 20a side of the transmission line 20, S21 is the ratio of high-frequency power that passes to the other end 20b side of the transmission line 20, and S31 is the power receiver 4 is a ratio of the high-frequency power output from the output side of 4 to the impedance matching circuit 6. FIG. 8 shows the characteristics of S33 of the S parameters. Curve a shows the characteristics when the impedance matching circuit 6 is omitted, and curve b shows the characteristics when the impedance matching circuit 6 performs impedance matching. Yes. S33 is a ratio of the high frequency power reflected when the impedance matching circuit 6 side is seen from the load 5.

  In the characteristic diagram of FIG. 6, when the frequency is about 2.45 GHz, S11 is about −3 dB, S21 is about −18 dB, and S31 is about −5 dB. On the other hand, in the characteristic diagram of FIG. 7, when the frequency is about 2.45 GHz, S11 is about -21 dB, S21 is about -22 dB, and S31 is about -1 dB. That is, by causing the impedance matching circuit 6 to perform impedance matching, reflection that occurs on the transmission line 20 is reduced. In addition, by doing so, the high-frequency power passing to the other end 20b side of the transmission line 20 is slightly reduced, and the high-frequency power output to the output side of the power receiver 4 is increased. Further, regarding S33 shown in the characteristic diagram of FIG. 8, when the frequency is about 2.45 GHz, the curve a is about −2 dB, while the curve b is about −33 dB. This indicates that the impedance matching is performed by the impedance matching circuit 6 in the curve b.

  FIG. 9 is a characteristic diagram of a sample experiment when impedance matching is performed in the impedance matching circuit 6 using a variable impedance element. When the frequency is about 2.39 GHz, S11 is about −15 dB, S21 is about −46 dB, and S31 is about −2.5 dB. Although the resonance frequency is shifted slightly lower than in the simulation experiment, S11 is sufficiently low, and reflection occurring on the transmission line 20 is reduced.

  For reference, FIG. 10 shows a characteristic diagram of a simulation experiment when the impedance matching is adjusted by the impedance matching circuit 6 when the reflector 7 is omitted. When the frequency is about 2.5 GHz, S11 is about -7.5 dB, S21 is about -7 dB, S31 is about -2.5 dB, and S33 is about -35 dB. Thus, if the reflector 7 is omitted, it can be seen that even if impedance matching is performed by the impedance matching circuit 6, it is not easy to reduce reflection that occurs on the transmission line 20.

  The wireless power transmission system according to the embodiment of the present invention has been described above. However, the present invention is not limited to that described in the above-described embodiment, and various modifications within the scope of the matters described in the claims. Design changes are possible.

DESCRIPTION OF SYMBOLS 1 Wireless power transmission system 2 Wireless power transmission device 20 Transmission line 20a One end of transmission line 20b The other end of transmission line 21 High frequency power supply 22 Non-reflective termination 3 Mobile wireless power receiving device 4 Power receiver 5 Load 6 Impedance matching circuit 7 Reflector

Claims (7)

A resonant power receiver that electromagnetically couples to a transmission line that sends high frequency power from one end to the other;
An impedance matching circuit connected between the output side of the power receiver and the load for impedance matching;
A resonant reflector that electromagnetically couples to the transmission line on the other end side of the transmission line from the power receiver;
Comprising
In order to reduce reflection that occurs on the transmission line by the power receiver, the high-frequency power that the reflector has reached is reflected to generate a reflected wave on the transmission line toward one end thereof, and the power receiver A mobile wireless power receiving apparatus, wherein the reflected wave is absorbed and output to the impedance matching circuit.   2. The mobile wireless power according to claim 1, wherein the power receiver is resonated at a half wavelength of the high frequency power and electromagnetically coupled to the transmission line at a quarter wavelength of the high frequency power. Power receiving device.   3. The mobile type according to claim 1, wherein the reflector is resonated at a half wavelength of the high frequency power and electromagnetically coupled to the transmission line at a quarter wavelength of the high frequency power. Wireless power receiver.   The position interval between a portion where the power receiver is electromagnetically coupled to the transmission line and a portion where the reflector is electromagnetically coupled to the transmission line is an odd multiple of a quarter wavelength of high frequency power. The mobile wireless power receiving apparatus according to any one of claims 1 to 3.   The impedance matching circuit includes a variable impedance element, and the impedance of the variable impedance element can be changed in response to a change in output impedance of the power receiver. The mobile wireless power receiving apparatus according to claim 1. The mobile wireless power receiving device according to any one of claims 1 to 5,
A wireless power transmission device having the transmission line and a high-frequency power source connected to one end thereof and a non-reflective terminal connected to the other end;
A wireless power transmission system comprising:   The wireless power transmission system according to claim 6, wherein the transmission line is a microstrip line.

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