JP2019176697A - Electrode unit, power transmitting device, power receiving device, and wireless power transmission system - Google Patents

Abstract

To suppress reduction in power transmission efficiency when a conductor is present in the vicinity of a transmission electrode or a power reception electrode.SOLUTION: An electrode unit is used in a power transmission device or a power reception device in a wireless power transmission system of an electric field coupling type. The electrode unit includes: an electrode group including at least two electrodes for performing power transmission or power reception of AC power; a conductor disposed close to at least one electrode in the electrode group; and a bandstop circuit having one end connected to the conductor and the other end grounded, the bandstop circuit suppressing propagation of energy of the frequency of the AC power from the at least one electrode to the ground sequentially via the conductor and the bandstop circuit.SELECTED DRAWING: Figure 12A

Description

  The present disclosure relates to an electrode unit, a power transmission device, a power reception device, and a wireless power transmission system.

  In recent years, development of wireless power transmission technology for transmitting power wirelessly, that is, contactlessly, to devices with mobility, such as a mobile phone and an electric vehicle, has been promoted. Wireless power transmission technologies include electromagnetic induction methods and electric field coupling methods. Among these, in the wireless power transmission system using the electric field coupling method, AC power is wirelessly transmitted from the pair of power transmission electrodes to the pair of power reception electrodes in a state where the pair of power transmission electrodes and the pair of power reception electrodes face each other. Such a wireless power transmission system using an electric field coupling method is used for, for example, a purpose of transmitting power from a pair of power transmission electrodes provided on a road surface or a floor surface to a load. Patent Document 1 discloses an example of a wireless power transmission system using such an electric field coupling method.

International Publication No. 2013/140665

  The present disclosure provides a technique for suppressing a decrease in power transmission efficiency when a conductor is present in the vicinity of a power transmission electrode or a power reception electrode.

  The electrode unit according to an aspect of the present disclosure is used for a power transmission device or a power reception device in an electric field coupling type wireless power transmission system. The electrode unit includes an electrode group including at least two electrodes that transmit or receive AC power, a conductor disposed in proximity to at least one electrode in the electrode group, and one end connected to the conductor. A band-stop circuit having the other end grounded, and a band that suppresses the propagation of the frequency energy of the AC power from the at least one electrode to the ground via the conductor and the band-stop circuit in order. A blocking circuit.

  The comprehensive or specific aspect of the present disclosure may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium. Or you may implement | achieve with arbitrary combinations of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

  According to the technology of the present disclosure, it is possible to suppress a decrease in power transmission efficiency even when a conductor is present in the vicinity of a power transmission electrode or a power reception electrode.

FIG. 1 is a diagram schematically illustrating an example of a wireless power transmission system using an electric field coupling method. FIG. 2 is a diagram illustrating a schematic configuration of the wireless power transmission system illustrated in FIG. 1. FIG. 3A is a diagram schematically illustrating a leakage electric field in the wireless power transmission system illustrated in FIGS. 1 and 2. FIG. 3B is a diagram illustrating an example of an intensity distribution of an electric field formed around the power transmission electrodes 120a and 120b during power transmission. FIG. 4A is a diagram schematically illustrating an example in which a conductive shield 550 is disposed between the power transmission electrodes 120a and 120b. FIG. 4B schematically illustrates an example in which other conductive shields 560a and 560b covering the two gaps between the power transmission electrode 120a and the conductive shield 550 and between the power transmission electrode 120b and the conductive shield 550 are arranged. FIG. FIG. 5 is a perspective view schematically showing the arrangement relationship between the power transmission electrodes 120a and 120b and the shields 550, 560a, and 560b shown in FIG. 4B. FIG. 6 is a perspective view showing another configuration example for suppressing the leakage electric field. FIG. 7 is a diagram schematically showing an example of the distribution of the electric field formed around the power transmission electrodes 120a and 120b during power transmission in the system shown in FIG. FIG. 8 is a diagram schematically illustrating an example of a wireless power transmission system in which each of the power transmission electrodes 120a and 120b is divided into two parts. FIG. 9 is a diagram showing a schematic configuration of the wireless power transmission system shown in FIG. FIG. 10 is a diagram for explaining the effect of suppressing the leakage electric field in the configuration shown in FIGS. 8 and 9. FIG. 11 is a diagram schematically showing the influence of the external conductor. FIG. 12A is a plan view schematically showing a power transmission electrode unit 150 and a power reception electrode unit 250 in an exemplary embodiment of the present disclosure. FIG. 12B is a plan view schematically showing the power transmission electrode unit 150 in an exemplary embodiment of the present disclosure. FIG. 13A is a diagram for explaining the configuration and operational effects of the band rejection circuit 420. FIG. 13B is a diagram for explaining the configuration and operational effects of the band rejection circuit 420. FIG. 14A is a perspective view schematically showing an example in which the power receiving electrode unit 250 includes an additional conductor 410 and a band rejection circuit 420. FIG. 14B is a perspective view schematically showing another example in which the power receiving electrode unit 250 includes the additional conductor 410 and the band rejection circuit 420. FIG. 15 is a plan view schematically illustrating a configuration of a power transmission device according to another embodiment. FIG. 16 is a diagram schematically illustrating a power transmission electrode unit 150 and a power reception electrode unit 250 in still another embodiment. FIG. 17 is a diagram schematically illustrating a power receiving device in still another embodiment. 18A is a perspective view illustrating an electrode configuration used in Example 1. FIG. 18B is a cross-sectional view showing the electrode configuration used in Example 1. FIG. FIG. 19A is a diagram illustrating an example of a configuration in which a ground conductor does not exist. FIG. 19B is a diagram illustrating an example of a configuration in which two ground conductors 580 are arranged in proximity to the power transmission electrodes 120a and 120b at both ends in the power transmission electrode group. FIG. 19C is a diagram illustrating a configuration of the second embodiment in which two additional conductors 410 and two band rejection circuits 420 are further provided in addition to the configuration of FIG. 19B. FIG. 20 is a perspective view illustrating the configuration of the third embodiment. FIG. 21 is a block diagram schematically showing a configuration related to power transmission in the wireless power transmission system of the present embodiment. FIG. 22 is a circuit diagram illustrating a more detailed configuration example of the wireless power transmission system. FIG. 23A is a diagram schematically illustrating a configuration example of the power transmission circuit 110. FIG. 23B is a diagram schematically illustrating a configuration example of the power receiving circuit 210.

(Knowledge that became the basis of this disclosure)
Prior to describing the embodiments of the present disclosure, the knowledge underlying the present disclosure will be described.

  FIG. 1 is a diagram schematically illustrating an example of a wireless power transmission system using an electric field coupling method. The illustrated wireless power transmission system is a system that wirelessly transmits power to a moving body 10 such as an automatic guided vehicle (AGV) used for conveying articles in a factory. In this system, a pair of flat power transmission electrodes 120 a and 120 b are arranged on the floor 30. The moving body 10 includes a pair of power receiving electrodes facing the pair of power transmitting electrodes 120a and 120b. The moving body 10 receives AC power transmitted from the power transmission electrodes 120a and 120b by a pair of power reception electrodes. The received electric power is supplied to a load such as a motor, a secondary battery, or a capacitor for storing electricity that the moving body 10 has. Thereby, driving or charging of the moving body 10 is performed.

  FIG. 1 shows XYZ coordinates indicating X, Y, and Z directions orthogonal to each other. In the following description, illustrated XYZ coordinates are used. The direction in which the power transmission electrodes 120a and 120b extend is the Y direction, the direction perpendicular to the surface of the power transmission electrodes 120a and 120b is the Z direction, and the direction perpendicular to the Y direction and the Z direction, that is, the width direction of the power transmission electrodes 120a and 120b is the X direction. To do. Note that the orientation of the structure shown in the drawings of the present application is set in consideration of the ease of explanation, and does not limit the orientation when the embodiment of the present disclosure is actually implemented. Further, the shape and size of the whole or a part of the structure shown in the drawings do not limit the actual shape and size.

  In the following description, the power transmission electrodes 120a and 120b may be described as “power transmission electrode 120” without distinction. Similarly, the power receiving electrodes 220a and 220b may be described as “power receiving electrode 220” without distinction.

  FIG. 2 is a diagram illustrating a schematic configuration of the wireless power transmission system illustrated in FIG. 1. This wireless power transmission system includes a power transmission device 100 and a moving body 10. The power transmission device 100 includes a pair of power transmission electrodes 120a and 120b and a power transmission circuit 110 that supplies AC power to the power transmission electrodes 120a and 120b. The power transmission circuit 110 is an AC output circuit including an inverter circuit, for example. The power transmission circuit 110 converts DC power supplied from a DC power source (not shown) into AC power and outputs the AC power to the pair of power transmission electrodes 120a and 120b. A matching circuit that reduces impedance mismatch may be inserted before the power after AC conversion is applied to the power transmission electrode.

  The moving body 10 includes a power receiving device 200 and a load 330. The power receiving apparatus 200 includes a pair of power receiving electrodes 220a and 220b, and a power receiving circuit 210 that converts AC power received by the power receiving electrodes 220a and 220b into power required by the load 330 and supplies the power to the load 330. The power receiving circuit 210 may include various circuits such as a rectifier circuit or a frequency conversion circuit. A matching circuit that reduces impedance mismatch may be inserted before the power received by the power receiving electrode is output to the rectifier circuit.

  The load 330 is a device that consumes or stores electric power, such as a motor, a capacitor for power storage, or a secondary battery. By electric field coupling (hereinafter, also referred to as “capacitive coupling”) between the pair of power transmission electrodes 120a and 120b and the pair of power reception electrodes 220a and 220b, power is transmitted wirelessly in a state where the two are opposed to each other.

  In such an electric field coupling type wireless power transmission system, a conductor may be located in the vicinity of at least one of the power transmitting electrodes 120a and 120b and the power receiving electrodes 220a and 220b. Such a conductor may be provided intentionally or may enter unintentionally. In this specification, such a conductor may be referred to as an “external conductor”. When the external conductor is grounded, the grounded external conductor may be referred to as a “ground conductor”.

  A configuration in which a conductor is intentionally disposed in the vicinity of one of the electrodes may be employed, for example, for the purpose of suppressing leakage of an electric field around the electrode. In general, the capacity between the opposing power transmitting electrodes 120a and 120b and the power receiving electrodes 220a and 220b is small. For this reason, in order to transmit large electric power, it is necessary to apply a high voltage to the power transmission electrodes 120a and 120b. In that case, the strength of the electric field leaking around the power transmitting electrodes 120a and 120b and the power receiving electrodes 220a and 220b is also increased.

  FIG. 3A is a diagram schematically illustrating a leakage electric field in the wireless power transmission system illustrated in FIGS. 1 and 2. FIG. 3A shows only a pair of power transmission electrodes 120a and 120b among the components of the wireless power transmission system shown in FIG. An arrow in FIG. 3A schematically represents a part of a line of electric force between the power transmission electrodes 120a and 120b at a certain moment. As illustrated, a leakage electric field that does not contribute to power transmission occurs between the pair of power transmission electrodes 120a and 120b. The leakage electric field increases as the power transmission electrodes 120a and 120b are closer and as the transmitted power is larger.

  FIG. 3B is a diagram illustrating an example of an intensity distribution of an electric field formed around the power transmission electrodes 120a and 120b during power transmission. In FIG. 3B, the region where the electric field strength is high is drawn darker. In order to reduce the influence of exposure to a living body or interference with other electronic devices, it is required to narrow the range of a region having a high electric field intensity distributed around each electrode. For example, it is required that the electric field strength at a position away from each electrode by a predetermined distance does not exceed a reference value defined by the International Committee for Non-Ionizing Radiation Protection (ICNIRP).

  In order to suppress the influence of exposure of the leakage electric field to the human body or interference with other electronic devices, for example, a countermeasure for providing a sensor for detecting a person on the moving body 10 can be considered. When the sensor detects that there is a person in the vicinity of the electrode during power transmission, the safety can be improved by reducing the transmission power or stopping the power transmission. However, it is preferable from the viewpoint of safety that the electric field leakage region around the power transmission electrode and the power reception electrode is concentrated in the narrowest possible region.

  In order to solve this problem, a measure for arranging a conductor in the vicinity of the pair of power transmission electrodes 120a and 120b and / or the pair of power reception electrodes 220a and 220b can be considered. For example, the conductor may be disposed at a position such as between the electrodes, on the electrodes, or on the sides of the electrodes. By arranging the conductor, the electric field is shielded and the leakage electric field can be suppressed.

  FIG. 4A is a diagram schematically illustrating an example in which a conductive shield 550 is disposed between the power transmission electrodes 120a and 120b. In this example, by providing the conductive shield 550, compared with the configuration illustrated in FIG.

  FIG. 4B schematically illustrates an example in which other conductive shields 560a and 560b covering the two gaps between the power transmission electrode 120a and the conductive shield 550 and between the power transmission electrode 120b and the conductive shield 550 are arranged. FIG. In this example, by providing the shields 560a and 560b, the electric field above the gaps 570a and 570b is shielded, and the influence thereof is reduced. According to the configuration illustrated in FIG. 4B, it is possible to further limit the location where the electric field concentrates, as compared with the configuration illustrated in FIG.

  FIG. 5 is a perspective view schematically showing the arrangement relationship between the power transmission electrodes 120a and 120b and the shields 550, 560a, and 560b shown in FIG. 4B. The power transmission electrodes 120a and 120b and the shields 550, 560a, and 560b all have a flat plate structure and have a flat surface. Each of the power transmission electrodes 120a and 120b and the shields 550, 560a, and 560b may have at least a surface formed of a conductive material such as copper or aluminum.

  FIG. 6 is a perspective view showing another configuration example for suppressing the leakage electric field. In this example, two conductors 520a and 520b are respectively disposed on both sides of the pair of power transmission electrodes 120a and 120b with a gap therebetween. The two conductors 520a and 520b are arranged along the power transmission electrodes 120a and 120b and are grounded.

  FIG. 7 is a diagram schematically showing an example of the distribution of the electric field formed around the power transmission electrodes 120a and 120b during power transmission in the system shown in FIG. In this example, compared with the example of FIG. 3B, the leakage electric field on the side of the power transmission electrodes 120a and 120b can be reduced.

  In each of the above examples, the conductor or shield for suppressing the leakage electric field may be disposed in the vicinity of at least one of the power receiving electrodes 220a and 220b. In that case, a leakage electric field around the power receiving electrode can be suppressed.

  In addition to the above configuration, the leakage electric field can be suppressed by a configuration in which at least one of the power transmission electrodes 120a and 120b and the power reception electrodes 220a and 220b is divided into a plurality of portions. Hereinafter, an example of such a configuration will be described.

  FIG. 8 is a diagram schematically illustrating an example of a wireless power transmission system in which each of the power transmission electrodes 120a and 120b is divided into two parts. In the system shown in FIG. 8, unlike the system shown in FIG. 1, the power transmission device includes a first power transmission electrode group including a plurality of first power transmission electrodes 120a and a second power transmission electrode group including a plurality of second power transmission electrodes 120b. And. Two first power transmission electrodes 120a and two second power transmission electrodes 120b are alternately arranged at regular intervals in the first direction (in this example, the X direction) along the surfaces of the power transmission electrodes 120a and 120b. . The plurality of first power transmission electrodes 120a and the plurality of second power transmission electrodes 120b extend in parallel along the floor surface, and are disposed on substantially the same plane.

  The power receiving device includes a first power receiving electrode group including a plurality of first power receiving electrodes and a second power receiving electrode group including a plurality of second power receiving electrodes. At the time of power transmission, the plurality of first power receiving electrodes respectively face the plurality of first power transmitting electrodes, and the plurality of second power receiving electrodes respectively face the plurality of second power transmitting electrodes. In this state, power is wirelessly transmitted from the power transmission device to the moving body 10 including the power reception device.

  FIG. 9 is a diagram showing a schematic configuration of the wireless power transmission system shown in FIG. The power transmission device 100 in this example includes a power transmission electrode unit 150 and a power transmission circuit 110. The power transmission electrode unit 150 includes two first power transmission electrodes 120a and two second power transmission electrodes 120b. The power transmission circuit 110 is an AC output circuit including an inverter circuit, for example. The power transmission circuit 110 converts DC power supplied from a DC power source (not shown) into AC power and outputs the AC power to each of the power transmission electrodes 120a and 120b.

  The power transmission circuit 110 includes two terminals that output AC power. One terminal is connected to the two first power transmission electrodes 120a, and the other terminal is connected to the two second power transmission electrodes 120b. During power transmission, the power transmission circuit 110 applies a first voltage to the two first power transmission electrodes 120a, and applies a second voltage having a phase opposite to the first voltage to the two second power transmission electrodes 120b.

  In this example, the widths and arrangement intervals of the four power reception electrodes in the power reception electrode unit 250 are set substantially equal to the widths and arrangement intervals of the four power transmission electrodes in the power transmission electrode unit 150. At the time of power transmission, the two first power receiving electrodes 220a are opposed to the two first power transmitting electrodes 120a, respectively, and the two second power receiving electrodes 220b are respectively opposed to the two second power transmitting electrodes 120b. In this state, when AC power is output from the power transmission circuit 110, power is transmitted in a non-contact manner due to capacitive coupling between the power transmitting electrode group and the power receiving electrode group facing each other.

  FIG. 10 is a diagram for explaining the effect of suppressing the leakage electric field in the configuration shown in FIGS. 8 and 9. The arrows in the figure simply show part of the lines of electric force. FIG. 10 shows a situation at the moment when a positive (+) voltage is applied to each first power transmission electrode 120a and a negative (−) voltage is applied to each second power transmission electrode 120b. At other moments, a negative (−) voltage is applied to each first power transmission electrode 120a, and a positive (+) voltage is applied to each second power transmission electrode 120b. In FIG. 10, electric lines of force on the back side (−Z side) of the power transmission electrodes 120 a and 120 b are not shown.

  In this example, two first power transmission electrodes 120a to which a positive voltage is applied at a certain moment and two second power transmission electrodes 120b to which a negative voltage is applied are alternately arranged in the X direction. For this reason, the electric field formed by the first power transmission electrode 120a having the first voltage and the electric field formed by the second power transmission electrode 120b having the second voltage having the opposite phase are partially canceled. As a result, the strength of the electric field formed mainly on the gap between the first power transmission electrode 120a and the second power transmission electrode 120b is reduced. This effect similarly occurs between any two adjacent electrodes. For this reason, compared with the case where two comparatively wide power transmission electrodes as shown in FIG. 1 are used, for example, the leakage electric field in a region away from each electrode in the Z direction can be reduced.

  This effect can be obtained even when the number of each of the first power transmission electrode 120a and the second power transmission electrode 120b is different from two. The number of at least one of the first power transmission electrode 120a and the second power transmission electrode 120b is two or more, and at least a part of the first power transmission electrode 120a and the second power transmission electrode 120b may be alternately arranged. The number of first power transmission electrodes 120a may not match the number of second power transmission electrodes 120b. The width of each electrode can be set so that, for example, the total width of the first power transmission electrode group is equal to the total width of the second power transmission electrode group.

  The configuration in which the leakage electric field is suppressed by dividing the electrode may be applied to the power receiving electrode. In that case, the leakage electric field in the region covering the gap between the power receiving electrodes can be suppressed.

  According to the above configuration, the leakage electric field around the electrode can be effectively suppressed. However, the present inventors have discovered that there is a problem that power transmission efficiency is reduced due to an additional conductor or an outer conductor such as a shield, or an electrode increased by division. Hereinafter, this problem will be described.

  FIG. 11 is a diagram schematically showing the influence of the external conductor. In the example of FIG. 11, the grounded conductor 520 is disposed in the vicinity of one of the power transmission electrodes 120, and the conductor 560 is disposed at a position covering the gap between the two power reception electrodes 220. The conductor 520 causes unnecessary capacitive coupling with each electrode component of the power transmission electrode 120. The conductor 560 causes unnecessary capacitive coupling with each electrode component of the power receiving electrode 220. As a result, unnecessary capacitive coupling occurs between the electrodes 120a and 120b having the opposite phase included in the power transmission electrode 120 and between the electrodes 120a and 120b having the opposite phase included in the power receiving electrode 220. It corresponds to that. In this example, each electrode is not divided. However, in the configuration in which the power transmission electrode is divided as in the example shown in FIG. 8, unnecessary coupling between the power transmission electrodes further increases. Further, in the example of FIG. 8, the power receiving electrodes (not shown) are also divided, so that an unnecessary coupling capacity increases between the power receiving electrodes.

  When unnecessary coupling increases due to the influence of introduction of an external conductor or electrode division, energy transmitted from the power transmission electrode 120 becomes difficult to be transmitted via the coupling capacitance between the transmission and reception electrodes. This is because the input impedance is lower in the path through the external conductor and the unnecessary capacity generated between the antiphase electrodes in the power transmission electrode than in the energy transmission path through the coupling capacitance between the transmission and reception electrodes. This is due to the fact that When such a condition is satisfied, the total amount of energy transmitted to the power receiving electrode 220 among the energy input to the power transmitting electrode 120 decreases.

ここで、Ｃ_ｃは送電電極１２０と受電電極２２０の対向によって得られる結合容量を示し、Ｃ_１は送電電極内での不要な容量を示し、Ｃ_２は受電電極内での不要な容量を示す。各電極の近傍に外部導体を配置した場合、または、送電電極および受電電極内の逆位相を帯びた電極間の近接容量を増大させて配置した場合、不要容量Ｃ_１およびＣ_２が増加することになる。式（１）より、不要容量が増加するほど結合係数ｋは低下し、無線電力伝送システムが送受電極間で伝達できるエネルギー効率が原理的に低下する。 The coupling coefficient k between the power transmission electrode 120 and the power reception electrode 220 is defined by the following formula (1).

Here, C _c indicates a coupling capacity obtained by facing the power transmitting electrode 120 and the power receiving electrode 220, C ₁ indicates an unnecessary capacity in the power transmitting electrode, and C ₂ indicates an unnecessary capacity in the power receiving electrode. . When the outer conductor is disposed in the vicinity of each electrode, or when the proximity capacitance between the electrodes having opposite phases in the power transmission electrode and the power reception electrode is increased, the unnecessary capacitances C ₁ and C ₂ are increased. become. From equation (1), the coupling coefficient k decreases as the unnecessary capacity increases, and the energy efficiency that the wireless power transmission system can transmit between the transmitting and receiving electrodes decreases in principle.

  In this way, when conductors such as conductive shields, grounded conductors, or additional electrodes are placed in the vicinity of each electrode, or when the power transmission electrode and the power reception electrode are divided and arranged alternately For example, the leakage electric field around the electrode can be effectively suppressed. However, these configurations result in an effect of increasing unnecessary coupling in the power transmission electrode and the power reception electrode. In addition, even when a conductor such as a metal is used for the casing or component of the power transmission device or the power reception device, unnecessary coupling between the electrode and the conductor occurs. This also results in an effect of increasing unnecessary coupling in the power transmitting electrode or the power receiving electrode. In the electric field coupling type wireless power transmission, the upper limit of the transmission efficiency is limited by an unnecessary capacitance between the electrodes in the power transmission electrode and / or the power reception electrode, as is apparent from the equation (1). Unnecessary coupling in the power transmission electrode and / or the power reception electrode leads to a decrease in transmission efficiency.

  The present inventors have found the above problems and studied a configuration for solving the above problems. The present inventors have conceived that the above problem can be solved by a configuration in which a conductor is disposed in the vicinity of at least one of a power transmission electrode and a power reception electrode, and a band rejection circuit is connected to the conductor. The band rejection circuit may be provided between any electrode and the outer conductor, or between two adjacent electrodes, and may be grounded. The band rejection circuit suppresses the propagation of the energy of the frequency used for power transmission from the electrode to the ground via the conductor and the band rejection circuit. Hereinafter, an outline of an embodiment of the present disclosure will be described.

  The electrode unit according to an aspect of the present disclosure is used for a power transmission device or a power reception device in an electric field coupling type wireless power transmission system. The electrode unit includes an electrode group including at least two electrodes that transmit or receive AC power, a conductor disposed in proximity to at least one electrode in the electrode group, and one end connected to the conductor. A band-stop circuit having the other end grounded, and a band that suppresses the propagation of the frequency energy of the AC power from the at least one electrode to the ground via the conductor and the band-stop circuit in order. A blocking circuit.

  According to the above aspect, the electrode unit includes a band rejection circuit having one end connected to the conductor and the other end grounded. The band rejection circuit suppresses the frequency energy of the AC power from propagating from the at least one electrode to the ground via the conductor and the band rejection circuit in order. With such a configuration, unnecessary coupling in the power transmitting electrode and / or the power receiving electrode can be reduced. As a result, power transmission efficiency can be improved.

  In one embodiment, the band rejection circuit includes a capacitor and an inductor. The band rejection circuit faces the combined input impedance of the series circuit of the conductor and the band rejection circuit facing from the at least one electrode at the frequency from the at least one electrode when the band rejection circuit is not present. The input impedance of the conductor is increased. For example, the band rejection circuit increases the combined input impedance of the series circuit to more than twice the input impedance of the conductor facing the at least one electrode when the band rejection circuit is not present. The transmission efficiency can be improved as the combined input impedance of the series circuit of the conductor and the band rejection circuit facing from the at least one electrode is closer to infinity. The electrode unit may be used in an environment where a conductive outer conductor is disposed in the vicinity of the at least one electrode. In that case, the conductor is located, for example, between the at least one electrode and the outer conductor. The electrode unit may further include the outer conductor. The band rejection circuit and the outer conductor may be connected to each other via the ground.

  The electrode unit may further include a circuit board including the band rejection circuit and the outer conductor. The band rejection circuit and the outer conductor may be connected to the ground on the circuit board.

  The electrode group, the conductor, and the outer conductor may be located on the same plane.

  The outer conductor may be close to a first electrode located at an end of the electrode group. The conductor may be located between the outer conductor and the first electrode.

  The electrode group faces another electrode group when power is transmitted. The outer conductor may face the electrode group on the side opposite to the side where the other electrode group is located. The conductor may be located between the electrode group and the outer conductor.

  The electrode group includes a first electrode and a second electrode adjacent to each other. When power is transmitted, an alternating voltage having the frequency is applied to the first electrode and the second electrode. The conductor may be located between the first electrode and the second electrode.

  The conductor is a first conductor, and the band rejection circuit is a first band rejection circuit. The first conductor may be close to the first electrode. The first band rejection circuit suppresses propagation of energy in a band including the frequency from the first electrode to the ground through the first conductor and the first band rejection circuit in order. The electrode unit may further include a second conductor adjacent to the second electrode, and a second band rejection circuit having one end connected to the second conductor and the other end grounded. The second band rejection circuit suppresses the energy of the frequency from propagating from the second electrode to the ground via the second conductor and the second band rejection circuit in order.

  The electrode unit may further include a ground conductor connected to the first band rejection circuit and the second band rejection circuit and having conductivity. The first electrode and the second electrode may be disposed along a certain plane. The ground conductor may be in a position overlapping the first electrode and the second electrode when viewed from a direction perpendicular to the plane. The first conductor may be located between the first electrode and the ground conductor. The second conductor may be located between the second electrode and the ground conductor.

  In the form in which the electrode unit is mounted on the power transmission device, the electrode group is connected to a power transmission circuit that outputs AC power. The power transmission circuit includes, for example, an inverter circuit, and supplies AC power to the adjacent first electrode and second electrode in the electrode group. The power transmission circuit applies a first voltage to the first electrode and a second voltage having a phase opposite to the first voltage to the second electrode. Here, the “reverse phase” means a phase different by a value greater than 90 degrees and less than 270 degrees. The amplitude of the second voltage is typically approximately equal to the amplitude of the first voltage.

  In the form in which the electrode unit is mounted on the power receiving device, the first electrode and the second electrode receive AC power from the pair of power transmitting electrodes in the power transmitting device facing them. At this time, a first voltage is applied to the first electrode, and a second voltage having a phase opposite to the first voltage is applied to the second electrode. Again, the amplitude of the second voltage is typically approximately equal to the amplitude of the first voltage.

  In this specification, an electrode unit mounted on a power transmission device may be referred to as a “power transmission electrode unit”, and an electrode unit mounted on the power reception device may be referred to as a “power reception electrode unit”. When the electrode unit is mounted on the power transmission device, each electrode is referred to as a “power transmission electrode”. When the electrode unit is mounted on the power receiving device, each electrode is referred to as a “power receiving electrode”. During power transmission, the power transmission electrode group and the power reception electrode group face each other. Electric power is transmitted from the power transmission electrode group to the power reception electrode group by electric field coupling between them.

  A power transmission device according to an embodiment of the present disclosure includes the electrode unit described above and a power transmission circuit that supplies AC power to at least two electrodes in the electrode unit. The power transmission device may include a circuit board on which the power transmission circuit and the band rejection circuit are mounted.

  A power receiving device according to another embodiment of the present disclosure includes the electrode unit described above, and a power receiving circuit that converts AC power received by at least two electrodes in the electrode unit into DC power or other AC power and supplies the AC power to a load. Is provided. The power receiving device may include a circuit board on which the power receiving circuit and the band rejection circuit are mounted.

  A mobile body in still another embodiment of the present disclosure includes the above-described power receiving device and a load that consumes or accumulates the power received by the power receiving device.

  A wireless power transmission system according to still another embodiment of the present disclosure includes a power transmission device including a power transmission electrode unit and a power reception device including a power reception electrode unit. At least one of the power transmission electrode unit and the power reception electrode unit may have a configuration equivalent to that of the electrode unit described above.

  The power receiving device can be mounted on a moving body, for example. The moving body includes the power receiving device described above and a load (for example, a battery or a motor) that consumes or accumulates the power received by the power receiving device.

  The “moving body” in the present disclosure means any movable object that is driven by electric power. The moving body includes, for example, an electric vehicle including an electric motor and one or more wheels. Such a vehicle can be, for example, a transfer robot, an automated guided vehicle (AGV), an electric vehicle (EV), an electric cart, or an electric wheelchair. The “moving body” in the present disclosure includes a movable object having no wheels. For example, unmanned aerial vehicles (UAVs, so-called drones) such as biped robots and multicopters, manned electric aircraft, and elevators are also included in the “mobile body”.

  Hereinafter, embodiments of the present disclosure will be described more specifically. However, more detailed explanation than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. In addition, the inventor provides the accompanying drawings and the following description in order for those skilled in the art to fully understand the present disclosure, and is not intended to limit the subject matter described in the claims. Absent. In the following description, the same reference numerals are given to components having the same or similar functions.

(Embodiment)
FIG. 12A is a plan view schematically showing a power transmission electrode unit 150 and a power reception electrode unit 250 in an exemplary embodiment of the present disclosure. FIG. 12B is a plan view schematically showing the power transmission electrode unit 150 in the present embodiment. FIG. 12B also shows an outer conductor 580 that is an external element of the power transmission electrode unit 150. In this manner, the electrode units 150 and 250 can be used in an environment where the outer conductor 580 is disposed in the vicinity of at least one electrode.

  The power transmission electrode unit 150 includes two power transmission electrodes 120, a conductor 410 disposed close to one of the two power transmission electrodes 120, and a band rejection circuit 420. One end of the band rejection circuit 420 is connected to the conductor 410. The other end of the band rejection circuit 420 is grounded. The power receiving electrode unit 250 includes two power receiving electrodes 220.

  At the time of power transmission, an AC voltage having a predetermined frequency (hereinafter also referred to as “transmission frequency”) is applied to the two power transmitting electrodes 120 and the two power receiving electrodes. The band rejection circuit 420 suppresses the transmission frequency energy from propagating from the power transmission electrode 120 to the ground via the conductor 410 and the band rejection circuit 420 in order.

  FIG. 12B shows a situation in which a conductive outer conductor 580 exists in the vicinity of the power transmission electrode unit 150. The outer conductor 580 may be, for example, a metal included in a casing of the power transmission device, or a conductive shield provided in the vicinity of the electrode 120 in order to suppress leakage of an electric field during power transmission. The outer conductor 580 is grounded. For this reason, in the following description, the outer conductor 580 may be referred to as a “ground conductor”.

  When such an external conductor 580 exists in the vicinity of the electrode 120, unnecessary capacitive coupling occurs between the electrode 120 and the external conductor 580. As a result, a part of transmission energy leaks to the outer conductor 580, and transmission loss may occur. Therefore, in this embodiment, a conductor 410 (hereinafter also referred to as “additional conductor 410”) is disposed between the power transmission electrode 120 and the external conductor 580, and the band blocking circuit 420 is connected to the conductor 410. As a result, energy loss from the electrode 120 via the outer conductor 580 is suppressed.

  FIG. 13A and FIG. 13B are diagrams for explaining the configuration and operational effects of the band rejection circuit 420. FIG. 13A shows an equivalent circuit of the electrode portion when the additional conductor 410 and the band rejection circuit 420 are not provided. FIG. 13B shows an equivalent circuit of the electrode portion in the present embodiment in which the additional conductor 410 and the band rejection circuit 420 are provided.

  When the additional conductor 410 and the band rejection circuit 420 are not provided, as shown in FIG. 13A, an unnecessary capacitance Csh is generated between the electrode 120 and the outer conductor 580 connected to the ground (GND). In this case, the impedance of the outer conductor 580 facing the power transmission electrode 120 is represented by Z = 1 / jωCsh. Here, j represents an imaginary unit, and ω represents an angular frequency of transmission power. As the unnecessary capacitance Csh increases, the impedance decreases. Therefore, when the outer conductor 580 is close to the electrode 120, a part of energy to be sent from the power transmission electrode 120 to the power reception electrode 220 flows to the outer conductor 580. As a result, transmission efficiency decreases.

  On the other hand, in the present embodiment, a capacitor Csha is newly formed between the power transmission electrode 120 and the additional conductor 410 as shown in FIG. 13B. The band rejection circuit 420 functions as a parallel resonance circuit having a capacitance (capacitance) Cbef and an inductance Lbef. In other words, it is considered that a composite circuit is formed in which a capacitor having a capacitance Csha and a parallel resonant circuit including a capacitor having a capacitance Cbef and an inductor having an inductance Lbef are connected in series between the electrode 120 and the ground. Can do.

  The band rejection circuit 420 increases the input impedance Z1 of the combined series circuit of the conductor 410 facing the electrode 120 and the band rejection circuit 420 at the transmission frequency, more than the input impedance of the coupling capacitance between the transmission and reception electrodes. Further, the band rejection circuit 420 uses the input impedance Z1 of the path from the conductor 410 facing the electrode 120 to the external conductor 580 via the band rejection circuit 420 at the transmission frequency when the band rejection circuit 420 is not provided. The capacitance formed between the electrode 120 and the outer conductor 580 is increased more than the input impedance Z0. The band rejection circuit 420 uses the input impedance Z1 of the combined series circuit of the conductor 410 facing the electrode 120 and the band rejection circuit 420 as the input impedance Z0 of the conductor 410 facing the electrode 120 when the band rejection circuit 420 is not present. For example, it is increased more than twice. The band rejection circuit 420 is preferably an input of a composite series circuit formed by an unnecessary capacitance Csha between the conductor 410 and the electrode 120 facing the electrode 120 and an inductance Lbef and a capacitance Cbef in the band rejection circuit 420 at the transmission frequency. The impedance Z1 is increased to, for example, twice or more the impedance Z0 of the outer conductor 580 facing the electrode 120 when the band rejection circuit 420 is not present. The capacitors Csha, Cbef, and the inductance Lbef can be set to values at which the impedance Z1 is ideally infinite, for example. In reality, since the inductance Lbef includes a parasitic loss term, the impedance Z1 cannot take an infinite value. However, the band rejection circuit 420 can be designed so that the impedance Z1 takes a maximum value. In that case, the electrode 120 and the ground can be regarded as being substantially electrically open. As a result, it is possible to prevent a current from flowing from the electrode 120 to the ground.

  Thus, the LC circuit shown in FIG. 13B functions as a band rejection filter near the transmission frequency. Thereby, the loss of energy from the electrode 120 to the ground can be reduced, and the transmission efficiency of the original power transmission path via the coupling capacitance can be improved.

  In the present embodiment, the additional conductor 410 and the band rejection circuit 400 are included in the power transmission electrode unit 150. The additional conductor 410 and the band rejection circuit 400 may be included in the power receiving electrode unit 250. According to such a configuration, it is possible to suppress the influence of the external conductor located in the vicinity of the power receiving electrode 220.

  FIG. 14A is a perspective view schematically showing an example in which the power receiving electrode unit 250 includes an additional conductor 410 and a band rejection circuit 420. In this example, there is an outer conductor 580 that faces the power receiving electrode 220 on the side opposite to the side where the power transmitting electrode 120 is located. The outer conductor 580 can be, for example, a metal member in a casing of a moving body including the power receiving electrode unit 250 or a conductive shield for suppressing leakage of an electric field. The additional conductor 410 is disposed between the power receiving electrode 220 and the outer conductor 580. As an example of obtaining the same effect, as shown in FIG. 14B, the additional conductor 410 is disposed between the power receiving electrode 220 and the outer conductor 580, and the band element circuit 420 is disposed between the additional conductor 410 and the outer conductor 580. It is also possible to connect via. In the example of FIGS. 14A and 14B, unnecessary coupling between the power receiving electrode 220 and the outer conductor 580 can be suppressed during power transmission. For this reason, the loss of energy received by the power receiving device can be reduced.

  In the example of FIGS. 14A and 14B, the two power receiving electrodes 220 are arranged along a certain virtual plane. The outer conductor 580 is in a position overlapping the two power receiving electrodes 220 when viewed from the direction perpendicular to the plane. The additional conductor 410 may be disposed so as to at least partially overlap a region where the outer conductor 580 and the two power receiving electrodes 220 overlap when viewed from a direction perpendicular to the plane. The additional conductor 410 may have a size equal to or larger than that of each of the two power receiving electrodes 220 and the outer conductor 580.

  FIG. 15 is a plan view schematically illustrating a configuration of a power transmission device according to another embodiment. The power transmission device in this embodiment includes a power transmission electrode unit 150 and a power transmission circuit module 600. The power transmission electrode unit 150 includes two power transmission electrodes 120, an additional conductor 410, and a band rejection circuit 420 including an LC element connected to the additional conductor 410. The power transmission circuit module 600 includes a power transmission circuit 110 including an inverter circuit. In this example, the power transmission circuit 110 and the band rejection circuit 420 are provided on one circuit board provided in the power transmission circuit module 600. The band rejection circuit 420 is connected to a ground terminal provided on the circuit board. Thus, the band rejection circuit 420 may be disposed separately from the electrode 120 and the additional conductor 410.

  In the example of FIG. 15, the additional conductor 410 is disposed between two adjacent power transmission electrodes 120 in the power transmission electrode group. The two power transmission electrodes 120 are each driven with a high-frequency potential having an opposite phase. For this reason, in the space between the power transmission electrodes 120, a ground plane having a zero potential at a high frequency is virtually formed. According to the configuration of FIG. 15, unnecessary capacity between the two power transmission electrodes 120 via the above-described virtual ground plane can be reduced, and the power transmission efficiency can be improved.

  FIG. 16 is a diagram schematically illustrating a power transmission electrode unit 150 and a power reception electrode unit 250 in still another embodiment. In this embodiment, the power transmission electrode unit 150 includes two adjacent power transmission electrodes 120a and 120b, two conductors 410a and 410b, two band rejection circuits 420a and 420b, and a ground conductor 580. The power receiving electrode unit 250 includes two power receiving electrodes 220a and 220b. In the embodiment of FIG. 16, a ground conductor 580 having a relatively large size is arranged on the back side of the power transmission electrode group.

  The 1st power transmission electrode 120a and the 2nd power transmission electrode 120b are arrange | positioned along a certain virtual plane. The ground conductor 580 is in a position overlapping the power transmission electrodes 120a and 120b when viewed from the direction perpendicular to the plane. In the example of FIG. 16, the ground conductor 580 has a shape and dimensions that cover the two power transmission electrodes 120a and 120b when viewed from the direction perpendicular to the plane. The first conductor 410a is located between the first power transmission electrode 120a and the ground conductor 580. The second conductor 410b is located between the second power transmission electrode 120b and the ground conductor 580. The first band rejection circuit 420a is electrically connected between the first conductor 410a and the ground conductor 580. The second band rejection circuit 420b is electrically connected between the second conductor 410b and the ground conductor 580.

  At the time of power transmission, an AC voltage having a transmission frequency is applied to the first power transmission electrode 120a and the second power transmission electrode 120b. The first band rejection circuit 420a suppresses propagation of energy in the band including the transmission frequency from the first power transmission electrode 120a to the ground conductor 580 via the first conductor 410a and the first band rejection circuit 420a. Similarly, the second band rejection circuit 420b suppresses propagation of energy in the band including the transmission frequency from the second power transmission electrode 120b to the ground conductor 580 via the second conductor 410b and the second band rejection circuit 420b. . With such a configuration, it is possible to suppress a decrease in energy efficiency of the original power transmission through the coupling capacitance from the power transmission electrode 120 to the power reception electrode 220.

  FIG. 17 is a diagram schematically illustrating a power receiving device in still another embodiment. This power receiving apparatus includes a power receiving electrode unit 250 and a power receiving circuit module 700. The power receiving electrode unit 250 includes two power receiving electrodes 220a and 220b, two conductors 410a and 410b, a ground conductor 580, and two band rejection circuits 420a and 420b. The power receiving circuit module 700 includes a power receiving circuit 210 that converts AC power received by the power receiving electrodes 220a and 220b into AC power or DC power having a different frequency. In this example, the power receiving circuit 210 and the band rejection circuits 420a and 420b are provided on one circuit board included in the power receiving circuit module 700. The band rejection circuits 420a and 420b are directly connected to the ground conductor 580. Instead of being directly connected to the ground conductor 580, the band rejection circuits 420a and 420b may be connected to a ground terminal provided on the circuit board.

  The ground conductor 580 is disposed at a position covering the first power receiving electrode 220a and the second power receiving electrode 220b. The ground conductor 580 may be, for example, a conductive shield that suppresses a leakage electric field or a conductor included in a housing of a device on which the power receiving electrode unit 250 is mounted. The first conductor 410a is located between the first power receiving electrode 220a and the ground conductor 580. The second conductor 410b is located between the second power receiving electrode 220b and the ground conductor 580. The first band rejection circuit 420a is connected to the first conductor 410a. The second band rejection circuit 420b is connected to the second conductor 410b. The connection between the first conductor 410a and the first band rejection circuit 420a and the connection between the second conductor 410b and the second band rejection circuit 420b are performed on the substrate in the power receiving circuit module 700.

  With such a configuration, the flow of energy from the power receiving electrodes 220a and 220b to the ground conductor 580 can be suppressed. For this reason, the transmission efficiency of wireless power transmission can be improved.

  Next, examples and effects of the present disclosure will be described. The present inventors performed simulations on some examples described below, and verified the effects of the embodiments of the present disclosure.

  18A is a perspective view illustrating an electrode configuration used in Example 1. FIG. In Example 1, the power transmission electrode group includes two first power transmission electrodes 120a and two second power transmission electrodes 120b. Each electrode has a flat plate shape extending in the Y direction. A first voltage is applied to the two first power transmission electrodes 120a, and a second voltage having the same amplitude and opposite phase as the first voltage is applied to the two second power transmission electrodes 120b. On the back side of the power transmission electrode group (that is, the side opposite to the side where the power reception electrode group is located), the ground conductor 580 is provided close to only a part of each electrode in the Y direction. The ground conductor 580 has a shape extending in a direction (X direction) perpendicular to the direction in which each electrode extends. FIG. 18B is a cross-sectional view on the XZ plane of the region where the ground conductor 580 is provided.

  The facing distance between the power transmission electrode group and the ground conductor 580 was set to 4 mm. The gap between the power transmission electrode and the power reception electrode was set to 2 cm. The charging area length corresponding to the coupling length of the power transmitting electrode and the power receiving electrode was 45 cm. The intersection length (length in the Y direction) between the ground conductor 580 and the power transmission electrode group is set to 1/8 of the charging area length, and the intersection width (length in the X direction) covers the entire width of the charging area. Set. The width of the charging area is 30 cm.

  18A and 18B, the additional conductors 410a and 410b are disposed between the power transmission electrode group and the ground conductor 580. The opposing distance between the additional conductors 410a and 410b and the ground conductor 580 was set to 1 mm. An LC parallel resonance circuit as shown in FIG. 13B was selected as the band rejection circuits 420a and 420b connected to the additional conductors. The values of Cbef and Lbef were set so that the resonance frequency of the LC parallel resonance circuit was the same as the frequency of the transmitted energy of 500 kHz.

  The impedance on the power transmission side was 1.47Ω, the impedance on the power reception side was 4.6Ω, and a configuration in which a matching circuit was provided between the power transmission electrode group and the power transmission circuit and between the power reception electrode group and the power reception circuit was adopted.

  In such a configuration, power transmission is performed in three ways: when the ground conductor 580 is not close to the power transmission electrode group, when the ground conductor 580 is close to the power transmission electrode group, and when an additional conductor and a band rejection circuit are provided. Efficiency was calculated.

  Table 1 shows the calculation results. It was confirmed that by providing the additional conductor and the band rejection circuit, it is possible to greatly suppress the decrease in transmission efficiency of wireless power transmission.

  Next, a second embodiment of the present disclosure will be described with reference to FIGS. 19A to 19C. Also in Example 2, it will be described that by introducing the configuration of the present embodiment, the adverse effect of the proximity of the outer conductor on the transmission efficiency of wireless power transmission can be avoided.

  Also in Example 2, the power transmission electrode group includes two first power transmission electrodes 120a and two second power transmission electrodes 120b. FIG. 19A shows a configuration in which no ground conductor exists in the vicinity of the power transmission electrode group. FIG. 19B shows a configuration in which two ground conductors 580 are arranged extending in the Y-axis direction in proximity to the power transmission electrodes 120a and 120b at both ends in the power transmission electrode group. The power transmission electrode and the ground conductor are close to the same XY plane with a distance of 5 mm. FIG. 19C shows a configuration in which two additional conductors 410a and 410b and two band rejection circuits 420a and 420b are further provided in addition to the configuration of FIG. 19B. FIG. 19C shows this example, and FIGS. 19A and 19B show comparative examples. In this embodiment, the power transmission electrode group, each additional conductor 410a, 410b, and each ground conductor 580 are located on the same plane. The width of the additional conductor was 2 mm, and the distance between the power transmission electrode and the additional conductor was 1 mm. Further, the additional conductor and the ground conductor were close to each other with a spacing of 12 mm.

  For each of the three configurations shown in FIGS. 19A to 19C, the transmission efficiency when power was applied was calculated. Table 2 shows the calculation results.

  From this result, it can be seen that the configuration of the present embodiment in which the additional conductor 410 and the band rejection circuit 420 are provided can suppress the deterioration of the power transmission efficiency.

  Further, the electric field intensity distribution around the electrode group was calculated for each of the three configurations shown in FIGS. 19A to 19C. As a result, it was confirmed that the electric field leakage effect equivalent to that in FIG. 19B (see FIG. 7) can be obtained with the configuration in FIG. From this result, according to the configuration of this example, it was shown that both the effect of suppressing the leakage electric field on the side of the electrode group and the effect of suppressing the decrease in transmission efficiency can be obtained.

  Next, Embodiment 3 of the present disclosure will be described with reference to FIG. FIG. 20 is a perspective view illustrating the configuration of the third embodiment. In the third embodiment, as in the first and second embodiments, the power transmission electrode group includes four power transmission electrodes 120. An additional conductor 410 and a band rejection circuit 420 are provided between any two adjacent power transmission electrodes 120 in the power transmission electrode group. Other conditions are the same as in the second embodiment. The line width of the additional conductor 410 was 1 mm, and the additional conductor 410 was disposed so as to be positioned at the center of the adjacent power transmission electrodes 120a and 120b.

  The power transmission efficiency was compared between Example 3 shown in FIG. 20 and the comparative example shown in FIG. 19A. Table 3 shows the results.

  From the results shown in Table 3, it was confirmed that deterioration in power transmission efficiency caused by unnecessary capacity between two adjacent electrodes, which occurs when the electrodes are divided, can be avoided.

(Configuration related to power transmission)
Next, the configuration related to power transmission in the wireless power transmission system according to the embodiment of the present disclosure will be described in more detail. Note that the system configuration described below is merely an example, and may be changed as appropriate according to required functions and performance.

  FIG. 21 is a block diagram schematically showing a configuration related to power transmission in the wireless power transmission system of the present embodiment. Here, for simplicity, an example in which each of the power transmission electrode group and the power reception electrode group includes two electrodes will be described.

  The power transmission device 100 includes a power transmission circuit 110 that converts DC power supplied from an external DC power supply 310 into AC power, two power transmission electrodes 120a and 120b that transmit AC power, a power transmission circuit 110, and power transmission electrodes 120a and 120b. And a matching circuit 180 connected between them. In the present embodiment, the power transmission circuit 110 is electrically connected to the first and second power transmission electrodes 120a and 120b via the matching circuit 180, and outputs AC power to the first and second power transmission electrodes 120a and 120b. To do. The moving body 10 includes a power receiving device 200 and a load 330.

  The power receiving apparatus 200 is connected to two power receiving electrodes 220a and 220b that receive power by capacitive coupling with the two power transmitting electrodes 120a and 120b, the matching circuit 280 connected to the two power receiving electrodes 220a and 220b, and the matching circuit 280. The power receiving circuit 210 converts the received AC power into DC power and outputs the DC power. When the first power receiving electrode 220a faces the first power transmitting electrode 120a, a capacitive coupling is formed between the first power receiving electrode 220a and the first power transmitting electrode 120a. The second power receiving electrode 220b forms a capacitive coupling with the second power transmitting electrode when facing the second power transmitting electrode 120a. AC power is transmitted from the power transmitting apparatus 100 to the power receiving apparatus 200 in a non-contact manner through these two capacitive couplings.

  The sizes of the housing of the moving body 10, the power transmission electrodes 120a and 120b, and the power reception electrodes 220a and 220b in the present embodiment are not particularly limited, but may be set to the following sizes, for example. The length (size in the Y direction) of the power transmission electrodes 120a and 120b can be set within a range of 50 cm to 20 m, for example. The width (size in the X direction) of each of the power transmission electrodes 120a and 120b can be set within a range of 5 cm to 2 m, for example. Each size in the advancing direction and the horizontal direction of the housing of the moving body 10 can be set within a range of 20 cm to 5 m, for example. The length (size in the traveling direction) of the power receiving electrode 220a can be set within a range of 5 cm to 2 m, for example. The width (size in the horizontal direction) of the power receiving electrode 220a can be set within a range of 2 cm to 2 m, for example. However, it is not limited to these numerical ranges.

  The load 330 includes, for example, a driving electric motor and a storage capacitor, and is driven or charged by DC power output from the power receiving circuit 210.

  The electric motor can be any motor, such as a direct current motor, a permanent magnet synchronous motor, an induction motor, a stepping motor, a reluctance motor. The motor rotates the wheels of the moving body 10 via a shaft, gears, and the like to move the moving body 10. Depending on the type of motor, the power receiving circuit 210 may include various circuits such as a rectifier circuit, an inverter circuit, and an inverter control circuit. The power receiving circuit 210 may include a converter circuit that directly converts the frequency (transmission frequency) of the received energy (electric power) into a frequency for driving the motor in order to drive the AC motor.

  The capacitor for power storage can be a high-capacity and low-resistance capacitor such as an electric double layer capacitor or a lithium ion capacitor. By using such a capacitor as a capacitor, charging can be performed more rapidly than when a battery (secondary battery) is used. Note that a secondary battery (for example, a lithium ion battery) may be used instead of the capacitor. In this case, the time required for charging increases, but more energy can be stored. The moving body 10 moves by driving a motor with electric power stored in a capacitor or a secondary battery.

  When the moving body 10 moves, the storage amount (charge amount) of the capacitor or the secondary battery decreases. For this reason, recharging is required to continue the movement. Therefore, when the amount of charge falls below a predetermined threshold during movement, the moving body 10 moves to the vicinity of the power transmission device 100 and performs charging. The power transmission device 100 can be installed at a plurality of locations in the factory.

  FIG. 22 is a circuit diagram illustrating a more detailed configuration example of the wireless power transmission system. In the illustrated example, the matching circuit 180 in the power transmission device 100 includes a series resonance circuit 130s connected to the power transmission circuit 110, and a parallel resonance circuit 140p connected to the power transmission electrodes 120a and 120b and inductively coupled to the series resonance circuit 130s. Have The matching circuit 180 has a function of matching the output impedance of the power transmission circuit 110 with the input impedance of the power transmission electrodes 120a and 120b. The series resonant circuit 130s in the power transmission device 100 has a configuration in which the first coil L1 and the first capacitor C1 are connected in series. The parallel resonant circuit 140p in the power transmission device 100 has a configuration in which the second coil L2 and the second capacitor C2 are connected in parallel. The first coil L1 and the second coil L2 constitute a transformer that is coupled with a predetermined coupling coefficient. The turn ratio between the first coil L1 and the second coil L2 is set to a value that realizes a desired transformation ratio (step-up ratio or step-down ratio).

  The matching circuit 280 in the power receiving device 200 includes a parallel resonant circuit 230p connected to the power receiving electrodes 220a and 220b, and a series resonant circuit 240s connected to the power receiving circuit 210 and inductively coupled to the parallel resonant circuit 230p. The matching circuit 280 has a function of matching the output impedance of the power receiving electrodes 220 a and 220 b with the input impedance of the power receiving circuit 210. The parallel resonant circuit 230p has a configuration in which a third coil L3 and a third capacitor C3 are connected in parallel. The series resonance circuit 240s in the power receiving device 200 has a configuration in which a fourth coil L4 and a fourth capacitor C4 are connected in series. The third coil L3 and the fourth coil L4 constitute a transformer that is coupled with a predetermined coupling coefficient. The turn ratio between the third coil L3 and the fourth coil L4 is set to a value that realizes a desired transformation ratio.

  Note that the configuration of the matching circuits 180 and 280 is not limited to the configuration shown in FIG. For example, a parallel resonant circuit may be provided instead of each of the series resonant circuits 130s and 240s. A series resonance circuit may be provided instead of each of the parallel resonance circuits 140p and 230p. Further, one or both of the matching circuits 180 and 280 may be omitted. When the matching circuit 180 is omitted, the power transmission circuit 110 and the power transmission electrodes 120a and 120b are directly connected. When the matching circuit 280 is omitted, the power receiving circuit 210 and the power receiving electrodes 220a and 220b are directly connected. In the present specification, the configuration provided with the matching circuit 180 also corresponds to a configuration in which the power transmission circuit 110 and the power transmission electrodes 120a and 120b are electrically connected. Similarly, the configuration provided with the matching circuit 280 corresponds to a configuration in which the power receiving circuit 210 and the power receiving electrodes 220a and 220b are electrically connected.

  FIG. 23A is a diagram schematically illustrating a configuration example of the power transmission circuit 110. In this example, the power transmission circuit 110 includes a full-bridge inverter circuit including four switching elements (for example, transistors such as IGBT or MOSFET) and a control circuit 112. The control circuit 112 includes a gate driver that outputs a control signal that controls the on (conductive) and off (non-conductive) states of each switching element, and a processor such as a microcontroller (microcomputer) that causes the gate driver to output a control signal. Have Instead of the full-bridge inverter circuit shown in the figure, a half-bridge inverter circuit or another oscillation circuit such as a class E may be used. The power transmission circuit 110 may have various sensors for measuring a modulation / demodulation circuit for communication and voltage / current. In the case of including a modulation / demodulation circuit for communication, data can be transmitted to the power receiving apparatus 200 while being superimposed on AC power.

  Note that the present disclosure includes a mode in which a weak AC signal (for example, a pulse signal) is transmitted to the power receiving apparatus 200 for the purpose of transmitting data, not for the purpose of power transmission. Even in such a form, it can be said that weak electric power is transmitted. Therefore, transmitting a weak AC signal (for example, a pulse signal) is also included in the concept of “power transmission” or “power transmission”. Such a weak AC signal is also included in the concept of “AC power”.

  FIG. 23B is a diagram schematically illustrating a configuration example of the power receiving circuit 210. In this example, the power receiving circuit 210 is a full-wave rectifier circuit including a diode bridge and a smoothing capacitor. The power receiving circuit 210 may have another rectifier configuration. In addition to the rectifier circuit, the power receiving circuit 210 may include various circuits such as a constant voltage / constant current control circuit and a communication modulation / demodulation circuit. The power receiving circuit 210 converts the received AC energy into DC energy that can be used by the load 330. Various sensors for measuring the voltage and current output from the series resonant circuit 240s may be included in the power receiving circuit 210.

  As the coils in the resonance circuits 130s, 140p, 230p, and 240s, for example, planar coils or laminated coils formed on a circuit board, or litz wires or twisted wires formed of a material such as copper or aluminum are used. It can be a wound coil. As each capacitor in the resonant circuits 130s, 140p, 230p, and 240s, any type of capacitor having, for example, a chip shape or a lead shape can be used. It is also possible to cause the capacitance between two wirings via air to function as each capacitor. The self-resonant characteristic of each coil may be used in place of these capacitors.

  The DC power source 310 is, for example, a commercial power source, a primary battery, a secondary battery, a solar cell, a fuel cell, a USB (Universal Serial Bus) power source, a high-capacity capacitor (for example, an electric double layer capacitor), or a voltage connected to the commercial power source. It may be any power source such as a converter.

  The resonance frequency f0 of the resonance circuits 130s, 140p, 230p, and 240s is typically set to match the transmission frequency f during power transmission. The resonance frequency f0 of each of the resonance circuits 130s, 140p, 230p, and 240s may not exactly match the transmission frequency f. Each resonance frequency f0 may be set to a value within a range of about 50 to 150% of the transmission frequency f, for example. The frequency f of the power transmission can be set to, for example, 50 Hz to 300 GHz, 20 kHz to 10 GHz in one example, 20 kHz to 20 MHz in another example, and 80 kHz to 14 MHz in another example.

  In the present embodiment, there is a gap between the power transmitting electrodes 120a and 120b and the power receiving electrodes 220a and 220b, and the distance is relatively long (for example, about 10 mm). Therefore, the capacitances Cm1 and Cm2 between the electrodes are very small, and the coupling impedances of the power transmitting electrodes 120a and 120b and the power receiving electrodes 220a and 220b are very high (for example, about several kΩ). On the other hand, the input / output impedances of the power transmission circuit 110 and the power reception circuit 210 are as low as about several Ω, for example. In the present embodiment, the parallel resonant circuits 140p and 230p are arranged on the side close to the power transmitting electrodes 120a and 120b and the power receiving electrodes 220a and 220b, respectively, and the series resonant circuits 130s and 240s are located on the side close to the power transmitting circuit 110 and the power receiving circuit 210. Each is arranged. With such a configuration, impedance matching can be easily performed. The series resonance circuit is suitable for matching with an external circuit having a low input / output impedance because the input / output impedance becomes zero (0) at the time of resonance. On the other hand, the parallel resonant circuit has an infinite input / output impedance at the time of resonance, and is therefore suitable for matching with an external circuit having a high input / output impedance. Therefore, as shown in FIG. 22, impedance matching is facilitated by arranging a series resonant circuit on the output end side of the power circuit having a low output impedance and arranging a parallel resonant circuit on the electrode side having a high output impedance. Can be realized. Similarly, impedance matching in the power receiving device 200 can be suitably realized by disposing a parallel resonance circuit on the electrode side and a series resonance circuit on the load side.

  In the configuration in which the distance between the power transmitting electrodes 120a and 120b and the power receiving electrodes 220a and 220b is shortened or the dielectric is disposed between the electrodes, the coupling impedance between the electrodes is low, and thus the above asymmetry. It is not necessary to have a simple resonant circuit configuration. If there is no problem of impedance matching, the matching circuits 180 and 280 themselves may be omitted.

  Each electrode in the above embodiment has a structure extending in parallel in the same direction, but such a structure may not be used depending on the application. For example, each electrode may have a rectangular shape such as a square. As long as such a plurality of rectangular electrodes are arranged in one direction, the technique of the present disclosure can be applied. Further, it is not an essential requirement that the surfaces of all the electrodes are on the same plane. Furthermore, the surface of each electrode does not need to have a completely planar shape, and may have, for example, a curved shape or a shape including unevenness. If such a surface is also generally planar, it corresponds to a “planar surface”. Each electrode may be inclined with respect to the road surface.

  In the above embodiment, the description given regarding the electrode unit on the power transmission side can be directly applied to the electrode unit on the power reception side as long as there is no contradiction. Similarly, the description given regarding the electrode unit on the power reception side can be applied to the unit on the electrode on the power transmission side as long as there is no contradiction.

  As described above, the wireless power transmission system according to the embodiment of the present disclosure can be used as a system for conveying articles in a factory. The moving body 10 has a loading platform on which articles are loaded, and functions as a carriage that autonomously moves in the factory and conveys the articles to a necessary place. However, the wireless power transmission system and the moving body in the present disclosure are not limited to such applications, and can be used for various other applications. For example, the moving body is not limited to the AGV, but may be other industrial machines, service robots, electric vehicles, multicopters (drone), or the like. The wireless power transmission system is not limited to being used in a factory, and can be used in, for example, stores, hospitals, homes, roads, runways, and other places.

DESCRIPTION OF SYMBOLS 10 Mobile body 30 Road surface 100 Power transmission apparatus 110 Power transmission circuit 110, 120a, 120b Power transmission electrode 130s Series resonance circuit 140p Parallel resonance circuit 150 Power transmission electrode unit 180 Matching circuit 200 Power reception apparatus 210 Power reception circuit 220, 220a, 220b Power reception electrode 230p Parallel resonance circuit 240 s Series resonance circuit 250 Power receiving electrode unit 280 Matching circuit 310 DC power supply 330 Load 410 Conductor (additional conductor)
420 Band stop circuit 580 External conductor (grounding conductor)
600 Power transmission circuit module 700 Power reception circuit module

Claims (19)

An electrode unit used in a power transmission device or a power reception device in an electric field coupling type wireless power transmission system,
An electrode group including at least two electrodes for transmitting or receiving AC power; and
A conductor disposed proximate to at least one electrode in the electrode group;
A band rejection circuit having one end connected to the conductor and the other end grounded, wherein the frequency energy of the AC power is grounded from the at least one electrode through the conductor and the band rejection circuit in order. A band rejection circuit that suppresses propagation to
An electrode unit comprising: The band rejection circuit includes a capacitor and an inductor,
The band rejection circuit has a combined input impedance of a series circuit of the conductor facing the at least one electrode and the band rejection circuit at the frequency from the at least one electrode when the band rejection circuit is not present. Increasing the input impedance of the conductor facing,
The electrode unit according to claim 1. The band rejection circuit has a combined input impedance of a series circuit of the conductor facing the at least one electrode and the band rejection circuit at the frequency from the at least one electrode when the band rejection circuit is not present. Increasing the input impedance of the conductor facing more than twice
The electrode unit according to claim 1 or 2. The electrode unit is used in an environment where an outer conductor having conductivity is disposed in the vicinity of the at least one electrode,
The conductor is located between the at least one electrode and the outer conductor;
The electrode unit according to claim 1.   The electrode unit according to claim 4, further comprising the outer conductor.   The electrode unit according to claim 4 or 5, wherein the band rejection circuit and the outer conductor are connected to each other via the ground. A circuit board including the band rejection circuit and the outer conductor;
The band rejection circuit and the outer conductor are connected to the ground on the circuit board;
The electrode unit according to claim 6.   The electrode unit according to claim 4, wherein the electrode group, the conductor, and the outer conductor are located on the same plane. The outer conductor is close to a first electrode located at an end of the electrode group,
The conductor is located between the outer conductor and the first electrode;
The electrode unit according to claim 8. The electrode group is opposed to another electrode group when power is transmitted,
The outer conductor faces the electrode group on the side opposite to the side where the other electrode group is located,
The conductor is located between the electrode group and the outer conductor;
The electrode unit according to claim 4. The electrode group includes a first electrode and a second electrode adjacent to each other,
When power is transmitted, an alternating voltage of the frequency is applied to the first electrode and the second electrode,
The conductor is located between the first electrode and the second electrode;
The electrode unit according to claim 1. The electrode group includes a first electrode and a second electrode adjacent to each other,
When power is transmitted, an alternating voltage of the frequency is applied to the first electrode and the second electrode,
When the conductor is a first conductor and the band rejection circuit is a first band rejection circuit,
The first conductor is proximate to the first electrode;
The first band rejection circuit suppresses propagation of energy in a band including the frequency from the first electrode to the ground via the first conductor and the first band rejection circuit in order,
The electrode unit is
A second conductor proximate to the second electrode;
A second band rejection circuit having one end connected to the second conductor and the other end grounded, wherein the energy of the frequency sequentially passes from the second electrode to the second conductor and the second band rejection circuit. A second band rejection circuit for suppressing propagation to the ground via,
The electrode unit according to claim 1, further comprising: A ground conductor connected to the first band rejection circuit and the second band rejection circuit and having conductivity;
The first electrode and the second electrode are disposed along a plane,
The ground conductor is located at a position overlapping the first electrode and the second electrode when viewed from a direction perpendicular to the plane;
The first conductor is located between the first electrode and the ground conductor;
The second conductor is located between the second electrode and the ground conductor;
The electrode unit according to claim 12. An electrode unit according to any one of claims 1 to 13,
A power transmission circuit for supplying the AC power to the electrode group in the electrode unit;
A power transmission device comprising:   The power transmission device according to claim 14, further comprising a circuit board on which the power transmission circuit and the band rejection circuit are mounted. An electrode unit according to any one of claims 1 to 13,
A power receiving circuit that converts the alternating current power received by the electrode group in the electrode unit into alternating current power or direct current power having a different frequency;
A power receiving apparatus comprising:   The power receiving device according to claim 16, further comprising a circuit board on which the power receiving circuit and the band rejection circuit are mounted. A power receiving device according to claim 16 or 17,
A load that consumes or accumulates the power received by the power receiving device; and
A moving object comprising: A power transmission device;
A power receiving device;
With
At least one of the power transmission device and the power reception device includes the electrode unit according to any one of claims 1 to 14.
Wireless power transmission system.

Images