JP7836076B2 - Power transmission equipment and contactless power supply system - Google Patents

Description

This invention relates to a power transmission device that transmits power to a power receiving device equipped with power receiving electrodes that receive power and supply the received power to a load, using an electric field coupling method in a non-contact manner, and to a non-contact power supply system equipped with this power transmission device.

In recent years, electric vehicles and autonomous, unmanned electric vehicles have attracted attention, and various research and development efforts are underway. However, challenges remain in the widespread adoption of these electric vehicles, including the cost and weight of batteries, the length of charging time, the difficulty of recycling, and increased labor costs. One method being explored to address these challenges is the development of unmanned and contactless power supply technology.

One such non-contact power supply method is the electric field coupling method. In the electric field coupling method, power is transmitted non-contact by transmitting through space as electric field energy via a capacitor formed between the transmitting and receiving electrodes. The electric field coupling method offers high power reception efficiency and power output, and can be implemented at low cost, making it suitable for non-contact power supply requiring transmission equipment over a wide area. Therefore, the electric field coupling method is attracting attention as the mainstream method for non-contact power supply to electric vehicles and electric motor vehicles.

In this electric field coupling system, when the size of the transmitting electrode becomes large enough that it cannot be ignored relative to the wavelength of the high-frequency power, a voltage standing wave is generated at the transmitting electrode due to the incident wave of high-frequency power supplied from one end of the transmitting electrode and the reflected wave reflected by the other end of the transmitting electrode. At the nodes of the standing wave, the voltage becomes low, making it difficult to receive power if the receiving electrode is located at a node. On the other hand, there is a need for a power transmission device that can transmit power over a wide range to the receiving device.

In response to such demands, an invention has been proposed in which the power transmission electrodes are divided into multiple sections and connected in cascading order, while a left-handed circuit (phase-advancing circuit) that advances the phase of high-frequency power is interposed between each power transmission electrode (for example, Patent Documents 1 and 2).

Patent Document 1 presents a theoretical analysis and effectiveness of standing wave suppression using a left-handed circuit interposed between power transmission electrodes. According to Patent Document 1, the phase delay in the reflected wave can be corrected by phase leading using the left-handed circuit, resulting in the incident and reflected waves being in phase. This suppresses the generation of voltage standing waves at the power transmission electrodes, enabling power transmission over a wide range to the power receiving device.

This Patent Document 1 presents a symmetrical CLC circuit as a left-handed circuit, in which, for example, two capacitors are directly connected, and an inductor is connected in parallel between the two capacitors.

Furthermore, Patent Document 2 shows a specific structure for implementing the left-handed circuit presented in Patent Document 1 onto the power transmission electrode. Patent Document 2 uses a substrate loaded with multiple capacitors used as capacitors constituting the left-handed circuit.

Japanese Patent Publication No. 2014-227025 Japanese Patent Publication No. 2019-68581

However, in the structure described in Patent Document 2, increasing the number of transmission electrodes connected in cascading order to transmit power over a wide area to the power receiving device increases the required left-handed circuits, resulting in an increase in the number of circuit boards loaded with multiple capacitors. Therefore, this leads to increased component costs and higher implementation difficulty.

This invention was made to solve the above-mentioned problems, and aims to provide a power transmission device and a contactless power supply system that can transmit power to a power receiving device over a wide area while suppressing the generation of voltage standing waves with a simple configuration.

To achieve this objective, a first embodiment of the power transmission device of the present invention transmits power to a power receiving device equipped with power receiving electrodes that receive power and supply the received power to a load, using an electric field coupling method in a non-contact manner. The embodiment comprises a power transmission electrode section configured by cascading multiple power transmission electrodes that transmit power to the power receiving electrodes, and a high-frequency power supply section that supplies high-frequency power to the power transmission electrode section. The power transmission electrode section comprises multiple power transmission electrode forming layers on which the power transmission electrodes are formed, and a phase advance section for advancing the phase of the supplied high-frequency power, located at least in part between adjacent cascaded power transmission electrodes. The phase advance section includes a capacitor connected in series with the power transmission electrodes, and the capacitor is formed by capacitive coupling obtained from the overlap of adjacent power transmission electrodes formed on different power transmission electrode forming layers.

A second aspect of the power transmission device of the present invention is a power transmission device of the first aspect, wherein the power transmission electrode section comprises a pair of power transmission electrodes forming a power transmission electrode pair, and power supplied from the high-frequency power supply section is transmitted to the power transmission electrode pair. One power transmission electrode of the power transmission electrode pair is connected in cascaded order to one power transmission electrode of an adjacent power transmission electrode pair, and the other power transmission electrode is connected in cascaded order to the other power transmission electrode of the adjacent power transmission electrode pair, thereby connecting multiple power transmission electrode pairs in cascaded order. The phase advancement section is provided in at least a portion of the space between adjacent power transmission electrode pairs that are connected in cascaded order.

A third aspect of the power transmission device of the present invention is the power transmission device of the second aspect, wherein the phase advancement unit comprises an inductor for advancing the phase of the high-frequency power in cooperation with the capacitor, and the inductor is formed between a pair of power transmission electrodes provided on a predetermined pair of power transmission electrodes.

A fourth aspect of the power transmission device of the present invention is the power transmission device of the third aspect, wherein the inductor is composed of a single coil, one end of which is connected to one of the pair of power transmission electrodes, and the other end of which is connected to the other of the pair of power transmission electrodes.

A fifth aspect of the power transmission device of the present invention is a power transmission device of the third aspect, comprising a ground plate maintained at a reference potential, wherein the inductor comprises a first coil, one end of which is connected to one of the pair of power transmission electrodes and the other end of which is connected to the ground plate, and a second coil, one end of which is connected to the other of the pair of power transmission electrodes and the other end of which is connected to the ground plate.

A sixth aspect of the power transmission device of the present invention is the power transmission device of the fifth aspect, wherein the ground plate is formed on the side opposite to the side facing the receiving electrode with respect to the power transmission electrode forming layer, and includes a region that overlaps with the power transmission electrode when viewed from the receiving electrode side.

A seventh aspect of the power transmission device of the present invention is that, in the power transmission device of any of the third to sixth aspects, the inductor is provided as a predetermined power transmission electrode pair only for the power transmission electrode pair closest to and/or furthest from the high-frequency power supply unit.

An eighth aspect of the power transmission device of the present invention is that, in the power transmission device of any of the third to seventh aspects, the inductor is composed of a printed pattern coil formed by a pattern printed on a printed circuit board.

A ninth aspect of the non-contact power supply system of the present invention provides non-contact power supply to a load and comprises a power transmission device according to any of the first to eighth aspects, and a power receiving device equipped with a receiving electrode that non-contactly receives power transmitted from the power transmission electrode of the power transmission device using an electric field coupling method, and supplies the received power to the load.

According to a first embodiment of the power transmission device of the present invention, high-frequency power is supplied from a high-frequency power supply unit to a power transmission electrode unit, and power is transmitted non-contact from the power transmission electrode unit to the receiving electrode of a power receiving device by electric field coupling. The power transmission electrode unit is configured by connecting a plurality of power transmission electrodes in cascaded order, and a phase advance unit is provided at least in part between adjacent power transmission electrodes connected in cascaded order to advance the phase of the supplied high-frequency power. This phase advance unit suppresses the generation of voltage standing waves in the power transmission electrode unit, enabling power transmission to the power receiving device over a wide area. Furthermore, the power transmission electrode unit is provided with a plurality of power transmission electrode forming layers on which power transmission electrodes are formed, and a capacitor is formed by capacitive coupling obtained from the overlap of adjacent power transmission electrodes formed on different power transmission electrode forming layers, which is connected in series with the power transmission electrodes constituting the phase advance unit. In this way, the capacitor of the phase advance unit can be realized simply by providing an overlap of adjacent power transmission electrodes formed on different power transmission electrode forming layers. Therefore, this power transmission device has the effect of suppressing the generation of voltage standing waves with a simple configuration while transmitting power to power receiving devices over a wide area.

According to a second embodiment of the power transmission device of the present invention, in addition to the effects of the first embodiment, the following effects are achieved. Specifically, the power transmission electrode section is composed of a pair of power transmission electrodes, and power supplied from the high-frequency power supply section is transmitted to this power transmission electrode pair. One power transmission electrode of the power transmission electrode pair is connected in cascaded order to one power transmission electrode of an adjacent power transmission electrode pair, and the other power transmission electrode is connected in cascaded order to the other power transmission electrode of the adjacent power transmission electrode pair, thereby connecting multiple power transmission electrode pairs in cascaded order. The phase-advancing section is provided in at least a portion of the space between adjacent power transmission electrode pairs that are connected in cascaded order, and the capacitor of this phase-advancing section is realized simply by creating an overlap between adjacent power transmission electrodes formed on different power transmission electrode forming layers. Therefore, even if the power transmission electrode section is composed of a pair of power transmission electrode pairs connected in cascaded order, it has the effect of being able to transmit power to a power receiving device over a wide area while suppressing the generation of voltage standing waves with a simple configuration.

According to a third aspect of the power transmission device of the present invention, in addition to the effects of the second aspect, the following effects are achieved. Specifically, the phase advancement section advances the phase of high-frequency power by means of an inductor, in cooperation with a capacitor. This inductor is formed between a pair of power transmission electrodes provided on a predetermined power transmission electrode pair. This allows for the suppression of voltage standing wave generation with a simple configuration, achieved simply by creating an overlap between adjacent power transmission electrodes formed on different power transmission electrode formation layers, and by using this inductor.

According to the fourth aspect of the power transmission device of the present invention, in addition to the effects of the third aspect, the following effects are achieved. Specifically, since the inductor of the phase-advancing section is composed of a single coil with one end connected to one of the paired power transmission electrodes and the other end connected to the other of the paired power transmission electrodes, the number of components can be reduced.

According to the fifth aspect of the power transmission device of the present invention, in addition to the effects of the third aspect, the following effects are achieved. Specifically, a ground plate maintained at a reference potential is provided, and the inductor of the phase-advancing section is composed of a first coil, one end of which is connected to one of a pair of power transmission electrodes and the other end of which is connected to the ground plate, and a second coil, one end of which is connected to the other of the pair of power transmission electrodes and the other end of which is connected to the ground plate. As a result, by connecting the first coil and the second coil between the pair of power transmission electrodes via the ground plate, an inductor is formed between the power transmission electrodes, which has the effect of making inductor mounting easier.

According to the sixth aspect of the power transmission device of the present invention, in addition to the effects of the fifth aspect, the following effects are achieved. Specifically, since the ground plate is formed on the side opposite to the receiving electrode relative to the power transmission electrode forming layer, and includes a region that overlaps with the power transmission electrode when viewed from the receiving electrode side, the other end of the first coil, whose one end is connected to one of the paired power transmission electrodes, can be easily connected to the ground plate, and the other end of the second coil, whose one end is connected to the other of the paired power transmission electrodes, can be easily connected to the ground plate. Therefore, the degree of freedom in mounting the inductor can be increased.

According to the seventh aspect of the power transmission device of the present invention, in addition to the effects of any of the third to sixth aspects, the following effect is achieved. Specifically, since the inductor is provided only for the power transmission electrode pairs closest to and/or furthest from the high-frequency power supply unit as a predetermined power transmission electrode pair, the number of components can be reduced.

According to the eighth aspect of the power transmission device of the present invention, in addition to the effects of any of the third to seventh aspects, the following effect is achieved. Specifically, since the inductor is composed of a printed pattern coil formed by a pattern printed on a printed circuit board, the inductor is planar. Therefore, the volume required for mounting the inductor can be reduced, thus facilitating the mounting of the inductor.

According to the ninth aspect of the non-contact power supply system of the present invention, a power transmission device according to any of the first to eighth aspects is provided, and the power transmitted from the power transmission electrode of the power transmission device is received non-contact by the power receiving electrode of the power receiving device using an electric field coupling method. The power received by the power receiving device is then supplied to the load. This achieves the same effects as the corresponding power transmission devices of the first to eighth aspects.

(a) is a schematic front view of a power transmission device and contactless power supply system according to a first embodiment of the present invention, and (b) is a schematic plan view of the same power transmission device and contactless power supply system. (a) is a schematic diagram of the phase-advancing section provided in the power transmission device, (b) is an equivalent circuit diagram of the phase-advancing section, and (c) is an equivalent circuit diagram of the power transmission device. (a) is a schematic diagram showing one example of the construction of a capacitor in the co-phase-forward section, and (b) is a schematic diagram showing another example of the construction of the same capacitor. (a) is a schematic perspective view of a power transmission device according to a second embodiment of the present invention, and (b) is a schematic perspective view showing another example of the same power transmission device. (a) is an equivalent circuit diagram of a power transmission device according to a third embodiment of the present invention, and (b) is a schematic perspective view showing an implementation example of the power transmission device. (a) is a schematic perspective view showing another implementation example of the power transmission device, and (b) is a schematic perspective view showing yet another implementation example of the power transmission device. (a) is an equivalent circuit diagram of a power transmission device according to a fourth embodiment of the present invention, and (b) is a schematic perspective view showing an implementation example of the power transmission device. (a) is a schematic perspective view showing another implementation example of the power transmission device, and (b) is a schematic perspective view showing yet another implementation example of the power transmission device. (a) is an equivalent circuit diagram of a power transmission device according to a fifth embodiment of the present invention, and (b) is a schematic perspective view showing an example of the implementation of the power transmission device. (a) is a schematic perspective view showing another implementation example of the power transmission device, and (b) is a schematic perspective view showing yet another implementation example of the power transmission device. (a) is a schematic plan view showing the printed pattern coils that constitute the phase advancement section 50 of the power transmission device 10, and (b) is a cross-section view of the end when cut along the cutting line XIb shown in (a). (a) is a schematic diagram illustrating an example of forming a second power transmission electrode by sandwiching the first power transmission electrode, and (b) is a schematic diagram illustrating another example of forming a second power transmission electrode by sandwiching the first power transmission electrode.

The embodiments for carrying out the present invention will be described below with reference to the accompanying drawings. The embodiments described below are all preferred specific examples of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement positions of components, and connection configurations shown in the following embodiments are examples and are not intended to limit the present invention. Accordingly, components in the following embodiments that are not described in the independent claims representing the highest-level concept of the present invention will be described as optional components. Furthermore, in each figure, substantially identical components are denoted by the same reference numerals, and redundant explanations are omitted or simplified.

(First Embodiment)
First, the schematic configuration of the power transmission device 10 and contactless power supply system 1 according to the first embodiment of the present invention will be described with reference to Figures 1 to 3. Figure 1(a) is a schematic front view of the power transmission device 10 and contactless power supply system 1, and Figure 1(b) is a schematic plan view of the power transmission device 10 and contactless power supply system 1. However, in Figure 1(b), the travel path G is omitted.

Furthermore, Figure 2(a) is a schematic diagram of the phase-advancing unit 50 provided in the power transmission device 10, Figure 2(b) is an equivalent circuit diagram of the phase-advancing unit 50, and Figure 2(c) is an equivalent circuit diagram of the power transmission device 10. Also, Figure 3(a) is a schematic diagram showing one example of the construction of the capacitor 51 of the phase-advancing unit 50, and Figure 3(b) is a schematic diagram showing another example of the construction of the capacitor 51.

The contactless power supply system 1 is a system that supplies power to a load wirelessly (without contact). In the example shown in Figure 1, the contactless power supply system 1 uses a battery 31 mounted on a mobile body 30 traveling on a travel path G as the load, and supplies power to the battery 31 wirelessly. It consists of a power transmission device 10 fixedly installed on the travel path G and a power receiving device 20 provided on the mobile body 30.

The mobile unit 30 is exemplified by electric vehicles such as electric cars and automated guided vehicles (AGVs) that operate autonomously without a driver. In addition to the power receiving device 20 and battery 31, it has drive wheels 32 and driven wheels 33. The mobile unit 30 receives power transmitted wirelessly from the power transmission device 10 via the power receiving device 20, and charges the battery 31 by supplying the received power to it. The mobile unit 30 travels along the road G by driving the drive wheels 32 using the power from the charged battery 31.

Furthermore, the load powered by the contactless power supply system 1 may be a battery 31 or other device that operates using the supplied power (e.g., a motor). Also, the load does not necessarily need to be mounted on a self-propelled device such as the mobile unit 30; the power receiving device 20 and the load may be mounted on a non-self-propelled device, or the power receiving device 20 may be attached to the load itself.

The power transmission device 10 is a device that transmits (transmits) power to the power receiving device 20 using an electric field coupling method in a non-contact manner, and comprises at least a high-frequency power supply unit 14 and a power transmission electrode unit 40.

The high-frequency power supply unit 14 is a high-frequency inverter that generates high-frequency power from DC power or commercial power, and is fixed to or embedded in the travel path G. The high-frequency power generated by the high-frequency power supply unit 14 is supplied to the power transmission electrode unit 40.

The power transmission electrode section 40 comprises at least a first power transmission electrode forming layer 11a on which multiple first power transmission electrodes 11 are formed, a second power transmission electrode forming layer 12a on which multiple second power transmission electrodes 12 are formed, and a phase advance section 50 (see Figure 2(a)).

The first power transmission electrode 11 and the second power transmission electrode 12 correspond to the power transmission electrodes of the present invention and are each composed of flat conductors embedded directly beneath the road surface of the travel path G. One of the first power transmission electrodes 11 is set to a size (length) such that the wavelength of high-frequency power is negligible, and one of the second power transmission electrodes 12 is set to be shorter in size (length) than the first power transmission electrode 11. However, one of the second power transmission electrodes 12 may be set to be longer than the first power transmission electrode 11.

The first power transmission electrode forming layer 11a, on which multiple first power transmission electrodes 11 are formed, is located directly beneath the road surface of the travel path G. The second power transmission electrode forming layer 12a, on which multiple second power transmission electrodes 12 are formed, is located at a deeper position than the first power transmission electrode forming layer 11a. In other words, the first power transmission electrode forming layer 11a and the second power transmission electrode forming layer 12a are located at different positions (depths). These first and second power transmission electrode forming layers 11a and 12a correspond to the power transmission electrode forming layers of the present invention.

In this embodiment, the case in which the second power transmission electrode forming layer 12a is provided at a deeper position than the first power transmission electrode forming layer 11a is described. However, the first power transmission electrode forming layer 11a and the second power transmission electrode forming layer 12a only need to be provided at different positions (depths), and the second power transmission electrode forming layer 12a may be provided at a shallower position than the first power transmission electrode forming layer 11a.

As shown in Figure 1(b), the multiple first power transmission electrodes 11 formed in the first power transmission electrode forming layer 11a each have a pair of first power transmission electrodes 11, and these pairs of first power transmission electrodes 11 constitute a set of first power transmission electrode pairs 11b. Similarly, the multiple second power transmission electrodes 12 formed in the second power transmission electrode forming layer 12a each have a pair of second power transmission electrodes 12, and these pairs of second power transmission electrodes 12 constitute a set of second power transmission electrode pairs 12b. The power transmission electrode section 40 is constructed by connecting these first power transmission electrode pairs 11b and second power transmission electrode pairs 12b alternately in cascaded order.

Specifically, in any first power transmission electrode pair 11b, one of the first power transmission electrodes 11 constituting that first power transmission electrode pair 11b is connected in cascaded manner to one of the second power transmission electrodes 12 constituting the adjacent second power transmission electrode pair 12b, and the other first power transmission electrode 11 constituting that first power transmission electrode pair 11b is connected in cascaded manner to the other second power transmission electrode 12 constituting the adjacent second power transmission electrode pair 12b. In this way, the power transmission electrode section 40 has a transmission line through which high-frequency power is transmitted that is divided into multiple first power transmission electrodes 11 and multiple second power transmission electrodes 12.

This cascaded connection is formed with respect to both the second power transmission electrode pair 12b adjacent to the first power transmission electrode pair 11b on the upstream side (high-frequency power supply unit 14 side) and the second power transmission electrode pair 12b adjacent to the downstream side (opposite side from the high-frequency power supply unit 14).

Furthermore, in the power transmission electrode section 40, a second power transmission electrode pair 12b is installed on the side closest to the high-frequency power supply unit 14 (nearest side) and the side furthest from it (farthest side). The high-frequency power supply unit 14 is connected via a matching circuit (not shown) to one end of the second power transmission electrode 12 of the second power transmission electrode pair 12b located on the nearest side of the high-frequency power supply unit 14, and the other end is connected to the other second power transmission electrode 12 of the same pair. This allows the high-frequency power output from the high-frequency power supply unit 14 to be supplied to the power transmission electrode section 40.

As described above, the first and second power transmission electrodes 11 and 12, which are connected in cascaded order, are formed in the first or second power transmission electrode forming layer 11a or 12a, which are located at different positions (depths). These first and second power transmission electrodes 11 and 12, formed at different positions (depths), are arranged to form an overlapping region when viewed from the direction of arrow U in Figure 1(a).

Capacitive coupling is achieved through the overlap of adjacent first and second power transmission electrodes 11 and 12 formed in the first and second power transmission electrode forming layers 11a and 12a, which are located at different positions (depths). As shown in Figure 2(a), a capacitor 51 with capacitance C is formed in each overlapping region.

This capacitor 51 is obtained, for example, as shown in Figure 3(a), by sandwiching an insulating layer 15 made of an insulator with relative permittivity _εr and thickness d, forming a second power transmitting electrode 12 below the insulating layer 15, and forming a first power transmitting electrode 11 above the insulating layer 15 such that it overlaps with the second power transmitting electrode 12 by a predetermined overlap area S when viewed from the direction of arrow U. The thickness d of the insulating layer 15 is equal to the distance d between the first power transmitting electrode 11 and the second power transmitting electrode 12.

Alternatively, as shown in Figure 3(b), the capacitor 51 can also be obtained by creating an overlap of a predetermined overlap area S between the adjacent first power transmitting electrode 11 and second power transmitting electrode 12, and then inserting a spacer 16 of length d made of an insulator between them, and fixing the first power transmitting electrode 11, the spacer 16, and the second power transmitting electrode 12 with an insulating bolt 17 and an insulating nut 18. The length d of the spacer 16 is equal to the distance d between the first power transmitting electrode 11 and the second power transmitting electrode 12. In this case, the insulating layer between the first power transmitting electrode 11 and the second power transmitting electrode 12 is air. The relative permittivity _εr of air is approximately 1.

On the other hand, as shown in Figures 1(a), 1(b), and 2(a), the power transmission electrode section 40 has a coil 13 with inductance L between the pair of second power transmission electrodes 12 in each second power transmission electrode pair 12b. However, in the second power transmission electrode pairs 12b located on the nearest and furthest sides of the high-frequency power supply section 14, a coil 13 with inductance 2L is provided between the pair of second power transmission electrodes 12. The coil 13 is either air-cored or has a three-dimensional shape using a ferrite core. This coil 13 corresponds to the inductor of the present invention.

Thus, for adjacent first power transmission electrode pairs 11b and second power transmission electrode pairs 12b, two capacitors 51 with capacitance C are connected in series between one first power transmission electrode 11 and one second power transmission electrode 12. Similarly, two capacitors 51 with capacitance C are connected in series between the other first power transmission electrode 11 and one second power transmission electrode 12. Furthermore, a coil 13 with inductance L is connected in parallel between one first power transmission electrode 11 and the other first power transmission electrode 11.

With the configuration of the capacitor 51 and coil 13 described above, a symmetrical CLC circuit, as shown in Figure 2(b), is formed between the first power transmission electrode pair 11b adjacent to the second power transmission electrode pair 12b on the upstream side (high-frequency power supply unit 14 side) and the first power transmission electrode pair 11b adjacent to the downstream side (opposite the high-frequency power supply unit 14).

Specifically, as shown in Figure 2(c), the power transmission electrode section 40 is represented by an equivalent circuit in which a symmetrical CLC circuit, as shown in Figure 2(b), is cascaded between the adjacent first power transmission electrode pair 11b and the second power transmission electrode pair 12b. This symmetrical CLC circuit, as described in Patent Documents 1 and 2, forms a phase-advancing section 50 in which the capacitor 51 and the coil 13 (inductor) work together to advance the phase of the high-frequency power.

Furthermore, in the power transmission electrode section 40, on the nearest and furthest sides of the high-frequency power supply section 14, a capacitor 51 with capacitance C formed between one of the paired first power transmission electrodes 11 and 12 is connected in series with the first power transmission electrode 11, and a capacitor 51 with capacitance C formed between the other first power transmission electrode 11 and 12 is connected in series with the other first power transmission electrode 11. Additionally, a coil 13 (inductor) with inductance 2L between the paired second power transmission electrodes 12 is connected in parallel between one first power transmission electrode 11 and the other first power transmission electrode 11.

With the above configuration, in the power transmission electrode section 40, circuits 50a and 50b, as shown in Figure 2(c), are formed in cascaded connection to the nearest and furthest sides of the high-frequency power supply section 14. When combined, circuits 50a and 50b are equivalent to a single symmetrical CLC circuit, and together circuits 50a and 50b form a single phase-advancing section 50.

Here, the capacitance C of the capacitor 51 and the inductance L (and 2L) of the coil 13 in the phase-advancing unit 50 are appropriately determined based on the size (length) of the first power-transmitting electrode 11, the size (length) of the second power-transmitting electrode 12, etc. The capacitance C of the capacitor 51 is expressed by the following equation (1). Here, ε0 is the permittivity of vacuum.

C=ε _r ε ₀ S/d (1)
The power transmission electrode section 40 can form a capacitor 51 with a desired capacitance C by changing at least one of the distance d between the first power transmission electrode 11 and the second power transmission electrode 12, the overlapping area S, and the relative permittivity _εr .

As shown in Figures 1(a) and (b), the power receiving device 20 includes at least a pair of receiving electrodes 21 that receive power transmitted from the first power transmitting electrode 11 and the second power transmitting electrode 12 in a non-contact manner using an electric field coupling method.

Specifically, each pair of receiving electrodes 21 is composed of a flat conductor. When the mobile body 30 is traveling along the travel path G, viewed from the direction of arrow U, one receiving electrode 21 is positioned to overlap with one of the pair of first transmitting electrodes 11 or one of the pair of second transmitting electrodes 12, while the other receiving electrode 21 is positioned to overlap with the other of the pair of first transmitting electrodes 11 or the other of the pair of second transmitting electrodes 12.

The power received by the receiving electrode 21 is supplied to the battery 31 via a matching circuit and a rectifier circuit (not shown).

The power transmission device 10 and the contactless power supply system 1, configured as described above, operate as follows:

The high-frequency power output from the high-frequency power supply unit 14 is supplied to the power transmission electrode unit 40. When the mobile body 30 travels along the travel path G, and the receiving electrode 21 of the power receiving device 20 on the mobile body 30 faces the first power transmission electrode 11 or the second power transmission electrode 12 of the power transmission electrode unit 40, a capacitor is formed between the receiving electrode 21 and the first power transmission electrode 11, or between the receiving electrode 21 and the second power transmission electrode 12. The power transmitted to the first power transmission electrode 11 and the second power transmission electrode 12 is transmitted to the receiving electrode 21 non-contact via an electric field coupling method, where the power propagates through space as electric field energy.

The power received by the receiving electrode 21 is supplied to the battery 31, and the battery 31 is charged. The mobile unit 30 travels along the road G by using the power from the charged battery 31 to drive the drive wheels 32.

Here, in the power transmission electrode section 40, the transmission line is divided into a plurality of first power transmission electrodes 11 and a plurality of second power transmission electrodes 12, and the first power transmission electrodes 11 and the second power transmission electrodes 12 are connected alternately in cascaded order. Furthermore, in the power transmission electrode section 40, a phase-advancing section 50 is formed between adjacent cascaded first power transmission electrodes 11 by a capacitor 51 formed by capacitive coupling obtained from the overlap of adjacent first power transmission electrodes 11 and second power transmission electrodes 12, and by an inductor coil 13 provided in parallel between a pair of second power transmission electrodes 12, thus connecting them in cascaded order.

When high-frequency power is transmitted from a single high-frequency power supply unit 14 to a transmission line over a long distance, the phase of the high-frequency power lags. Furthermore, reflected waves from the far end of the transmission line are also present, and voltage standing waves are generated due to the relative phase relationship between the forward and reflected waves.

In contrast, in this first embodiment, a phase advancement section 50 is formed between adjacent first transmission electrodes 11 that are connected in cascaded order, thus canceling out the phase delay of the high-frequency power transmitted through the first and second transmission electrodes 11 and 12. Furthermore, the size (length) of each first and second transmission electrode 11 and 12 is set to a length that allows the wavelength of the high-frequency power to be ignored, so the phase delay of the high-frequency power within each first and second transmission electrode 11 and 12 is also negligible.

Therefore, regardless of the location of the mobile body 30 on the power transmission electrode section 40, impedance mismatch can be kept to a minimum, the generation of voltage standing waves in the power transmission electrode section 40 is suppressed, and power can be transmitted to the power receiving device 20 over a wide range.

The power transmission device 10 and contactless power supply system 1 described above provide the following effects.

(1) The power transmission electrode section 40 is provided with a first power transmission electrode forming layer 11a on which the first power transmission electrode 11 is formed, and a second power transmission electrode forming layer 12a on which the second power transmission electrode 12 is formed. A capacitor 51 with capacitance C that constitutes the phase advance section 50 is formed by capacitive coupling obtained from the overlap of the first power transmission electrode 11 and the second power transmission electrode 12, which are adjacent to each other but at different positions (depths), and is connected in series with the first power transmission electrode 11. In this way, the capacitor 51 of the phase advance section 50 can be realized simply by providing an overlap of adjacent power transmission electrodes formed in different power transmission electrode forming layers, without the need to prepare a capacitor as a component. Therefore, the power transmission device 10 and the contactless power supply system 1 are configured to transmit high-frequency power to a wide range of devices while suppressing the generation of voltage standing waves with a simple configuration. This is achieved by dividing the transmission line of the power transmission electrode section 40 into multiple first power transmission electrodes 11 and multiple second power transmission electrodes 12, and connecting them in a cascaded manner while overlapping them alternately.

(2) The power transmission electrode section 40 is composed of a pair of first power transmission electrodes 11 to form a first power transmission electrode pair 11b, and a pair of second power transmission electrodes 12 to form a second power transmission electrode pair 12b. These first power transmission electrode pairs 11b and second power transmission electrode pairs 12b are alternately connected in cascaded configuration. Specifically, one first power transmission electrode 11 of the first power transmission electrode pair 11b is connected in cascaded configuration to one second power transmission electrode 12 of the adjacent second power transmission electrode pair 12b, and the other first power transmission electrode 11 is connected in cascaded configuration to the other second power transmission electrode 12 of the adjacent second power transmission electrode pair 12b. The power supplied from the high-frequency power supply section 14 is transmitted through these alternately connected first power transmission electrode pairs 11b and second power transmission electrode pairs 12b. The phase-shifting unit 50 is provided between adjacent first power transmission electrode pairs 11b and second power transmission electrode pairs 12b that are connected in cascaded order. The capacitor 51 of this phase-shifting unit 50 is realized simply by creating an overlap between the first power transmission electrodes 11 and the second power transmission electrodes 12, which are at different positions (depths). Therefore, even if the power transmission electrode unit 40 is configured such that a pair of first power transmission electrode pairs 11b, composed of a pair of first power transmission electrodes 11, and a pair of second power transmission electrode pairs 12b, composed of a pair of second power transmission electrodes 12, are alternately connected in cascaded order, power can be transmitted to the power receiving device 20 over a wide area while suppressing the generation of voltage standing waves with a simple configuration.

(3) The phase advancement unit 50 advances the phase of the high-frequency power through the cooperation of the capacitor 51 and the inductor coil 13. This coil 13 is formed between the pair of second transmission electrodes 12 provided on the second transmission electrode pair 12b. As a result, the capacitor 51, which is realized simply by creating an overlap between the first transmission electrode 11 and the second transmission electrode 12 at different positions (depths), and this coil 13, can suppress the generation of voltage standing waves with a simple configuration.

(4) The inductor provided in the phase advancement section 50 of (1) is composed of a single coil 13, with one end connected to one of the paired second power transmission electrodes 12 and the other end connected to the other of the paired second power transmission electrodes 12. Therefore, the number of components can be reduced.

(Second Embodiment)
Next, with reference to Figure 4, a power transmission device 10 according to a second embodiment of the present invention will be described. Figure 4(a) is a schematic perspective view of the power transmission device 10, and Figure 4(b) is a schematic perspective view showing another example of the power transmission device 10. In Figures 4(a) and (b), the same reference numerals are used for components identical to those in the power transmission device 10 according to the first embodiment, and their explanation is omitted here. Furthermore, the contactless power supply system 1 according to the second embodiment has the same configuration as the contactless power supply system 1 according to the first embodiment, except that the power transmission device 10 of the second embodiment is used instead of the power transmission device 10 of the first embodiment, so its explanation is omitted.

In the power transmission device 10 according to the second embodiment, a ground plate 19 is provided below the first power transmission electrode 11 and the second power transmission electrode 12, with an insulating layer in between. The ground plate 19 is a flat conductor maintained at a reference potential, and is formed on the side opposite to the side facing the receiving electrode 21 relative to the first power transmission electrode forming layer 11a and the second power transmission electrode forming layer 12a (see Figure 1(a)), including a region that overlaps with the first power transmission electrode 11 and the second power transmission electrode 12 when viewed from the receiving electrode 21 side.

By providing the ground plate 19, it is possible to suppress the effects of high-frequency power transmitted to the first and second power transmission electrodes 11 on various objects beneath the road surface of the travel path G, such as the ground or under the floor, and conversely, to suppress the effects of such objects on the high-frequency power transmitted to the first and second power transmission electrodes 11 and 12.

Furthermore, in the power transmission device 10 according to the second embodiment, the inductor of the phase-advancing unit 50 provided on the second power transmission electrode pair 12b is formed via a ground plate 19. Specifically, the inductor is composed of a first coil 13a with an inductance of L/2, one end of which is connected to one of the paired second power transmission electrodes 12 and the other end of which is connected to the ground plate 19, and a second coil 13b with an inductance of L/2, one end of which is connected to the other of the paired second power transmission electrodes 12 and the other end of which is connected to the ground plate.

Specifically, the inductor of the phase-advancing unit 50 is divided into two coils, a first coil 13a and a second coil 13b, which are connected in series and mounted. The first coil 13a and the second coil 13b are either air-core or ferrite-core three-dimensional structures. These series-connected first coil 13a and second coil 13b act equivalently to the coil 13 with inductance L according to the first embodiment.

Furthermore, as shown in Figure 4(a), for all second power transmission electrode pairs 12b on which inductors are provided, the inductor may be divided into a first coil 13a and a second coil 13b for implementation.

Furthermore, among the second power transmission electrode pairs 12b on which inductors are provided, the inductors may be divided into a first coil 13a and a second coil 13b for some of the second power transmission electrode pairs 12b, while the remaining second power transmission electrode pairs 12b may be implemented using a single coil 13, similar to the first embodiment. For example, in the example shown in Figure 4(b), one coil 13 is implemented in the second power transmission electrode pairs 12b provided on the nearest and furthest sides of the high-frequency power supply unit 14, while the first coil 13a and the second coil 13b are implemented in the other second power transmission electrode pairs 12b to constitute the inductor of the phase-advancing unit 50.

Furthermore, the inductances of the first coil 13a and the second coil 13b do not necessarily have to be L/2; their respective inductances may be adjusted so that their combined inductance is L.

The power transmission device 10 according to the second embodiment described above provides the following effects.

(5) A ground plate 19 maintained at a reference potential is provided. The inductor of the phase advancement unit 50 is composed of a first coil 13a, one end of which is connected to one of the paired second power transmission electrodes 12 and the other end of which is connected to the ground plate 19, and a second coil 13b, one end of which is connected to the other of the paired second power transmission electrodes 12 and the other end of which is connected to the ground plate 19. This allows the sizes of the first coil 13a and the second coil 13b to be smaller than those of the coil 13 according to the first embodiment. Furthermore, even if an insulating layer or the like exists between the first power transmission electrodes 11 and 2 power transmission electrodes 12 and the ground plate 19, the first coil 13a and the second coil 13b can be easily connected between the paired second power transmission electrodes 12 via the ground plate 19. Therefore, coupled with the miniaturization of the first coil 13a and the second coil 13b, the inductor between the second power transmission electrodes 12 can be easily mounted.

(6) The ground plate 19 is formed on the side opposite to the receiving electrode 21 with respect to the first power transmitting electrode forming layer 11a and the second power transmitting electrode forming layer 12a, and includes a region that overlaps with the first power transmitting electrode 11 and the second power transmitting electrode 12 when viewed from the receiving electrode 21 side. Therefore, the other end of the first coil 13a, whose one end is connected to one of the paired second power transmitting electrodes 12, can be easily connected to the ground plate 19, and the other end of the second coil 13b, whose one end is connected to the other of the paired second power transmitting electrodes 12, can be easily connected to the ground plate 19. Thus, the degree of freedom in mounting the inductor can be increased.

Furthermore, the power transmission device 10 according to the second embodiment achieves the same effects as the power transmission device 10 according to the first embodiment through the same configuration. Also, the contactless power supply system 1 equipped with the power transmission device 10 according to the second embodiment achieves the same effects as the power transmission device 10.

(Third Embodiment)
Next, with reference to Figures 5 and 6, a power transmission device 10 according to a third embodiment of the present invention will be described. Figure 5(a) is an equivalent circuit diagram of the power transmission device 10, Figure 5(b) is a schematic perspective view showing an example of the implementation of the power transmission device 10, Figure 6(a) is a schematic perspective view showing another example of the implementation of the power transmission device 10, and Figure 6(b) is a schematic perspective view showing yet another example of the implementation of the power transmission device 10.

In Figures 5 and 6, the same reference numerals are used for components identical to those in the power transmission device 10 of the first and second embodiments, and their explanation is omitted here. Furthermore, the contactless power supply system 1 of the third embodiment is identical in configuration to the contactless power supply system 1 of the first embodiment, except that the power transmission device 10 of the third embodiment is used instead of the power transmission device 10 of the first and second embodiments; therefore, its explanation is omitted.

In the third embodiment, as shown in the equivalent circuit of Figure 5(a), the inductors of the phase-advancing unit 50, which were connected in parallel to each second power-transmitting electrode pair 12b in the first or second embodiment, are combined into a single inductor, and this combined inductor is provided only to the second power-transmitting electrode pair 12b located closest to the high-frequency power supply unit 14.

For example, when constructing a phase-advancing unit 50 equivalent to the power transmission device 10 according to the first embodiment shown in Figure 2(c) using the third embodiment, if we assume that in Figure 2(c), a coil 13 with inductance 2L is mounted in parallel on the nearest and furthest sides of the high-frequency power supply unit 14, and that n other coils 13 with inductance L are mounted in parallel, then in the third embodiment, it is sufficient to provide an inductor with a combined inductance of L/(n+1) only on the second power transmission electrode pair 12b located on the nearest side of the high-frequency power supply unit 14.

Even if a single composite inductor is provided only on the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14, the cooperation between this single inductor and the capacitors 51 formed by the overlap of the adjacent first power transmission electrode 11 and second power transmission electrode 12 allows for the phase advancement of the high-frequency power, thereby suppressing the generation of voltage standing waves in the power transmission electrode unit 40.

The inductor of the phase-advancing unit 50 according to this third embodiment may be implemented, for example, by connecting one coil 13 with inductance L/(n+1) between the second power transmission electrodes 12b of the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14, as shown in Figure 5(b), in the same manner as in the first embodiment.

Furthermore, as shown in Figure 6(a), if a ground plate 19 similar to that of the second embodiment is provided, the first coil 13a and the second coil 13b, having an inductance of L/(2(n+1)), may be connected via the ground plate 19 between the second power transmission electrode 12 of the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14, via the ground plate 19, similar to Figure 4(a) of the second embodiment. Note that as long as the combined inductance of the first coil 13a and the second coil 13b is L/(n+1), the individual inductances can be any value.

Furthermore, even if a ground plate 19 is provided, it goes without saying that, as shown in Figure 6(b), it may also be implemented by connecting a single coil 13 with inductance L/(n+1) between the second power transmission electrodes 12b of the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14, in the same manner as in the first embodiment.

The power transmission device 10 according to the third embodiment described above provides the following effects.

(7) Since the inductor constituting the phase advancement unit 50 is provided only for the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14, the number of components can be reduced, lowering costs. Furthermore, ease of implementation can be improved.

(8) By combining the inductors into a single unit, the required inductance for that inductor can be reduced to L/(n+1). Therefore, the number of coils 13 or the first coil 13a and second coil 13b required to mount that inductor can be reduced. This allows for cost reduction and improved ease of mounting.

Furthermore, the power transmission device 10 according to the third embodiment achieves the same effects as the power transmission devices 10 according to the first and second embodiments through the same configuration. Also, the contactless power supply system 1 equipped with the power transmission device 10 according to the third embodiment achieves the same effects as the power transmission device 10.

(Fourth Embodiment)
Next, with reference to Figures 7 and 8, a power transmission device 10 according to the fourth embodiment of the present invention will be described. Figure 7(a) is an equivalent circuit diagram of the power transmission device 10, Figure 7(b) is a schematic perspective view showing an example of the implementation of the power transmission device 10, Figure 8(a) is a schematic perspective view showing another example of the implementation of the power transmission device 10, and Figure 8(b) is a schematic perspective view showing yet another example of the implementation of the power transmission device 10.

In Figures 7 and 8, components identical to those in the power transmission device 10 of the first to third embodiments are denoted by the same reference numerals, and their explanation is omitted here. Furthermore, the contactless power supply system 1 of the fourth embodiment is identical in configuration to the contactless power supply system 1 of the first embodiment, except that the power transmission device 10 of the fourth embodiment is used instead of the power transmission device 10 of the first to third embodiments; therefore, its explanation is omitted.

In the third embodiment, the inductors of the phase-advancing unit 50 connected in parallel to each of the second power-transmitting electrode pairs 12b in the first or second embodiment were combined into a single inductor, and this combined inductor was provided only to the second power-transmitting electrode pair 12b closest to the high-frequency power supply unit 14. However, in the fourth embodiment, as shown in the equivalent circuit of Figure 7(a), the combined inductor with inductance L/(n+1) is provided only to the second power-transmitting electrode pair 12b furthest from the high-frequency power supply unit 14.

Even when a single composite inductor is provided only at the second power transmission electrode pair 12b located furthest from the high-frequency power supply unit 14, similar to the third embodiment, this single inductor and the capacitors 51 formed by the overlap of the adjacent first power transmission electrode 11 and second power transmission electrode 12 work together to advance the phase of the high-frequency power, thereby suppressing the generation of voltage standing waves in the power transmission electrode unit 40.

The inductor of the phase-advancing unit 50 according to this fourth embodiment may be implemented, for example, by connecting one coil 13 with inductance L/(n+1) between the second power transmission electrodes 12b of the second power transmission electrode pair 12b located on the furthest side of the high-frequency power supply unit 14, as shown in Figure 7(b), in the same manner as in the first embodiment.

Furthermore, as shown in Figure 8(a), if a ground plate 19 similar to that in the second embodiment is provided, the first coil 13a and the second coil 13b, having an inductance of L/(2(n+1)), may be connected via the ground plate 19 between the second power transmission electrode 12 of the second power transmission electrode pair 12b located furthest from the high-frequency power supply unit 14, in the same manner as in Figure 4(a) of the second embodiment. Note that as long as the combined inductance of the first coil 13a and the second coil 13b is L/(n+1), the individual inductances can be any value.

Furthermore, even when a ground plate 19 is provided, as shown in Figure 8(b), it may be implemented by connecting a single coil 13 with inductance L/(n+1) between the second power transmission electrodes 12b of the second power transmission electrode pair 12b located on the furthest side of the high-frequency power supply unit 14, in the same manner as in the first embodiment.

According to the power transmission device 10 of the fourth embodiment described above, the inductor constituting the phase advancement section 50 is provided only for the second power transmission electrode pair 12b located furthest from the high-frequency power supply section 14, thereby achieving the same effects as in the third embodiment.

Furthermore, the power transmission device 10 according to the fourth embodiment achieves the same effects as the power transmission devices 10 according to the first and second embodiments through the same configuration. Also, the contactless power supply system 1 equipped with the power transmission device 10 according to the fourth embodiment achieves the same effects as the power transmission device 10.

(Fifth Embodiment)
Next, with reference to Figures 9 and 10, a power transmission device 10 according to the fifth embodiment of the present invention will be described. Figure 9(a) is an equivalent circuit diagram of the power transmission device 10, Figure 9(b) is a schematic perspective view showing an example of the implementation of the power transmission device 10, Figure 10(a) is a schematic perspective view showing another example of the implementation of the power transmission device 10, and Figure 10(b) is a schematic perspective view showing yet another example of the implementation of the power transmission device 10.

In Figures 9 and 10, components identical to those in the power transmission device 10 of the first to fourth embodiments are denoted by the same reference numerals, and their explanation is omitted here. Furthermore, the contactless power supply system 1 of the fifth embodiment is identical in configuration to the contactless power supply system 1 of the first embodiment, except that the power transmission device 10 of the fifth embodiment is used instead of the power transmission device 10 of the first to fourth embodiments; therefore, its explanation is omitted.

In the third and fourth embodiments, a case was described in which the inductors of the phase-advancing unit 50, which were connected in parallel to each of the second power-transmitting electrode pairs 12b in the first or second embodiment, are combined into a single inductor, and this combined inductor is provided only to the second power-transmitting electrode pair 12b located on the nearest or furthest side of the high-frequency power supply unit 14.

In contrast, in the fifth embodiment, as shown in the equivalent circuit of Figure 9(a), the inductors of the phase-advancing unit 50 connected in parallel to each second power-transmitting electrode pair 12b in the first or second embodiment are combined into two inductors. One of these is provided on the second power-transmitting electrode pair 12b closest to the high-frequency power supply unit 14, and the other is also provided on the second power-transmitting electrode pair 12b closest to the high-frequency power supply unit 14.

If the inductance of each inductor is 2L/(n+1), then a phase-advancing unit 50 equivalent to that of the power transmission device 10 in the first embodiment shown in Figure 2(c) (where two coils 13 with inductance 2L are mounted in parallel on the nearest and furthest sides of the high-frequency power supply unit 14, and n other coils 13 with inductance L are mounted in parallel) can be constructed in the fifth embodiment. Note that the inductances of the two inductors do not necessarily have to be 2L/(n+1); it is sufficient that the combined inductance of these two inductors is L/(n+1).

Even when the two combined inductors are provided on the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14 and the second power transmission electrode pair 12b located furthest away, similar to the third and fourth embodiments, the two inductors and the capacitors 51 formed by the overlap of the adjacent first power transmission electrode 11 and second power transmission electrode 12 work together to advance the phase of the high-frequency power, thereby suppressing the generation of voltage standing waves in the power transmission electrode unit 40.

The inductor of the phase-advancing unit 50 according to this fifth embodiment may be implemented, for example, as shown in Figure 9(b), by connecting one coil 13 with inductance 2L/(n+1) between the second power transmission electrodes 12 of the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14, and another coil 13 with inductance 2L/(n+1) between the second power transmission electrodes 12 of the second power transmission electrode pair 12b located furthest from the high-frequency power supply unit 14, in the same manner as in the first embodiment.

Furthermore, as shown in Figure 10(a), if a ground plate 19 similar to that of the second embodiment is provided, the first coil 13a and the second coil 13b, having an inductance of L/(n+1), may be connected via the ground plate 19 between the second power transmission electrodes 12 of the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14, similar to Figure 4(a) of the second embodiment. The first coil 13a and the second coil 13b, also having an inductance of L/(n+1), may be connected via the ground plate 19 between the second power transmission electrodes 12 of the second power transmission electrode pair 12b located furthest from the high-frequency power supply unit 14, similar to Figure 4(a) of the second embodiment.

Furthermore, the first coil 13a and the second coil 13b, mounted on the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14, may have arbitrary inductances as long as their combined inductance is L/(n+1). Similarly, the first coil 13a and the second coil 13b, mounted on the second power transmission electrode pair 12b located furthest from the high-frequency power supply unit 14, may also have arbitrary inductances as long as their combined inductance is L/(n+1).

Furthermore, even when a ground plate 19 is provided, as shown in Figure 10(b), it may be implemented by connecting one coil 13 with an inductance of 2L/(n+1) between the second power transmission electrodes 12b of the second power transmission electrode pairs 12b located on the nearest and furthest sides of the high-frequency power supply unit 14, in the same manner as in the first embodiment.

The power transmission device 10 according to the fifth embodiment described above provides the following effects.

(7) Since the inductors constituting the phase advancement unit 50 are provided only for the second power transmission electrode pair 12b located closest to the high-frequency power supply unit 14 and the second power transmission electrode pair 12b located furthest away, the number of components can be reduced compared to the first and second embodiments, thereby lowering costs. Furthermore, ease of mounting can also be improved.

(8) By combining the inductor into two inductors, the required inductance for that inductor can be reduced to 2L/(n+1). Therefore, compared to the first and second embodiments, the coil 13 or the first coil 13a and second coil 13b required to mount the inductor can be reduced. Therefore, cost reduction and ease of mounting can be improved.

(9) Since the phase advance unit 50 is composed of two inductors, it can advance the phase of high-frequency power with greater precision compared to the third and fourth embodiments, which are composed of one inductor.

Furthermore, the power transmission device 10 according to the fifth embodiment achieves the same effects as the power transmission devices 10 according to the first and second embodiments through the same configuration. Also, the contactless power supply system 1 equipped with the power transmission device 10 according to the fifth embodiment achieves the same effects as the power transmission device 10.

(Sixth Embodiment)
Next, with reference to Figure 11, a power transmission device 10 according to the sixth embodiment of the present invention will be described. Figure 11(a) is a schematic plan view showing the printed pattern coil 13c constituting the phase advancement section 50 of the power transmission device 10, and Figure 11(b) is a cross-section view when cut along the cutting line XIb shown in Figure 11(a).

In Figures 11(a) and (b), the same reference numerals are used for components identical to those in the power transmission device 10 of the first to fifth embodiments, and their explanation is omitted here. Furthermore, the contactless power supply system 1 of the sixth embodiment is identical in configuration to the contactless power supply system 1 of the first embodiment, except that the power transmission device 10 of the sixth embodiment is used instead of the power transmission device 10 of the first to fifth embodiments; therefore, its explanation is omitted.

In the first to fifth embodiments, the case in which the phase-advancing unit 50 uses a three-dimensional coil 13, a first coil 13a, and a second coil 13b made of an air core or ferrite core was described. In contrast, in the sixth embodiment, the coil 13, the first coil 13a, and the second coil 13b are composed of printed pattern coils 13c formed by patterns printed on a printed circuit board 60.

For example, as shown in Figures 11(a) and (b), a printed circuit board 60 is provided between the pair of second power transmission electrodes 12, and a rectangular coil pattern made of conductors is printed on the printed circuit board 60 to form a printed pattern coil 13c.

Furthermore, one end of the printed pattern coil 13c formed on the printed circuit board is connected to one of the paired second power transmission electrodes 12, and the other end of the printed pattern coil 13c is connected to the other of the paired second power transmission electrodes 12. Thus, the printed pattern coil 13c functions in the same way as the coil 13 of the phase advancement unit 50 in the first embodiment.

Furthermore, one end of the printed pattern coil 13c formed on the printed circuit board is connected to one or the other of the paired second power transmission electrodes 12, and the other end of the printed pattern coil 13c is connected to the ground plate 19 (see Figure 4(a)). Thus, the printed pattern coil 13c functions in the same way as the first coil 13a or the second coil 13b of the phase advancement unit 50 in the second embodiment.

The power transmission device 10 according to the sixth embodiment described above provides the following effects.

(10) Since the inductor of the phase-advancing unit 50 is composed of a printed pattern coil 13c formed by a pattern printed on the printed circuit board 60, the inductor is planar. Therefore, the volume required for mounting the inductor can be reduced, making it easier to mount the inductor.

Furthermore, the power transmission device 10 according to the sixth embodiment achieves the same effects as the power transmission devices 10 according to the first to fifth embodiments through the same configuration. Also, the contactless power supply system 1 equipped with the power transmission device 10 according to the sixth embodiment achieves the same effects as the power transmission device 10.

(Variant)
Although the present invention has been described above based on embodiments, it can be easily inferred that the present invention is not limited in any way to the above embodiments, and that various improvements and modifications are possible without departing from the spirit of the present invention.

For example, each embodiment may be constructed by modifying it by adding or replacing some or more components of other embodiments with those components. Furthermore, the numerical values given in the above embodiments are merely examples, and it is naturally possible to use other numerical values.

For example, in the above embodiments, the power transmission electrode section 40 was described in which the first power transmission electrode 11 is formed in the first power transmission electrode forming layer 11a, and the second power transmission electrode 12 is formed in the second power transmission electrode forming layer 12a, which is at a different position (depth) from the first power transmission electrode forming layer 11a, that is, the power transmission electrodes are formed in two layers. However, the power transmission electrodes may be composed of three or more layers. In this case, adjacent power transmission electrodes are formed in different layers, and the capacitor 51 of the phase-advancing section 50 can be formed by capacitive coupling due to the overlap of adjacent power transmission electrodes.

Furthermore, the second power transmission electrode 12 may be formed across multiple layers, sandwiching the first power transmission electrode 11. For example, as shown in Figure 12(a), the second lower power transmission electrode 12c is formed in the layer below the first power transmission electrode 11, and the second upper power transmission electrode 12d is formed in the layer above the first power transmission electrode 11. The second lower power transmission electrode 12c and the second upper power transmission electrode 12d are flat conductors with the same area, and they are stacked such that the overlapping area of the first power transmission electrode 11 and the second lower power transmission electrode 12c is the same as the overlapping area of the first power transmission electrode 11 and the second upper power transmission electrode 12d. The second lower power transmission electrode 12c and the second upper power transmission electrode 12d are electrically connected by a conductor 12e.

As a result, a capacitor with capacitance _CL is formed by capacitive coupling between the first transmission electrode 11 and the second lower transmission electrode 12c due to overlap, and a capacitor with capacitance _CU is formed by capacitive coupling between the first transmission electrode 11 and the second upper transmission electrode 12d due to overlap. Here, the second lower transmission electrode 12c and the second upper transmission electrode 12d can be considered as a single second transmission electrode 12 by the connection of the conductor 12e, and it is equivalent to forming a capacitor with capacitance ( _CL + _CU ) between this single second transmission electrode 12 and the first transmission electrode 11.

Furthermore, when it can be guaranteed that the distance between the second upper transmission electrode 12d and the second lower transmission electrode 12c remains constant, if the first transmission electrode 11 is formed further away from the second lower transmission electrode 12c and closer to the second upper transmission electrode 12d than designed, the capacitance _CL decreases, but this decrease is absorbed by the capacitance _CU . Also, if the first transmission electrode 11 is formed closer to the second lower transmission electrode 12c and further away from the second upper transmission electrode 12d than designed, the capacitance _CU increases, but this increase is absorbed by the capacitance _CL . As a result, the capacitance ( _CL + _CU ) between the second transmission electrode 12 and the first transmission electrode 11, which are considered as one, remains approximately constant, thus enabling the formation of a phase advance unit 50 that can advance the phase of high-frequency power with high accuracy.

As shown in Figure 12(b), the conductor 12e is not necessarily required, and the second upper transmission electrode 12d and the second lower transmission electrode 12c may exist independently. Even in this case, the second lower transmission electrode 12c and the second upper transmission electrode 12d can be virtually considered as a single second transmission electrode 12, and the same effects and advantages as in Figure 12(a) can be obtained.

In the embodiments described above, the inductors of the phase-advancing unit 50 were either provided for all second power transmission electrode pairs 12b or only for the nearest and/or furthest second power transmission electrode pairs 12b of the high-frequency power supply unit 14. However, the invention is not limited to these cases, and the inductors of the phase-advancing unit 50 may be provided for any second power transmission electrode pairs 12b. For example, the second power transmission electrode pairs 12b may be grouped into predetermined units, and the inductors within these predetermined units may be combined into a single inductor, which may then be provided for one second power transmission electrode pair 12b included in the predetermined unit. Reducing the number of inductors reduces the number of components used, thereby lowering costs, and also increases the flexibility of inductor mounting. On the other hand, by appropriately using multiple inductors, a phase-advancing unit 50 that can accurately advance the phase of high-frequency power can be constructed.

1. Contactless power supply system 10. Power transmission device 11. First power transmission electrode 11a. First power transmission electrode forming layer 11b. First power transmission electrode pair 12. Second power transmission electrode 12a. Second power transmission electrode forming layer 12b. Second power transmission electrode pair 13. Coil (inductor).
13a First coil (part of the inductor)
13b Second coil (part of the inductor)
13c Printed pattern coil 14 High-frequency power supply unit 19 Ground plate 20 Power receiving device 21 Power receiving electrode 31 Battery (load)
40 Power transmission electrode section 50 Phase advance section 51 Capacitor

Claims (9)

A power transmission device that transmits power to a power receiving device equipped with power receiving electrodes that receive power and supplies the received power to a load, using an electric field coupling method in a non-contact manner,
A power transmission electrode section is configured by connecting multiple power transmission electrodes in series to transmit power to the power receiving electrode,
It comprises a high-frequency power supply unit that supplies high-frequency power to the power transmission electrode section,
The aforementioned power transmission electrode section is
A plurality of power transmission electrode forming layers on which the power transmission electrodes are formed,
The system includes a phase advance unit for advancing the phase of the supplied high-frequency power, located at least in part between adjacent power transmission electrodes connected in cascade,
The phase advancement unit includes a capacitor connected in series with the power transmission electrode,
The power transmission device is characterized in that the capacitor is formed by capacitive coupling obtained from the overlap of adjacent power transmission electrodes formed on different power transmission electrode forming layers. The power transmission electrode section consists of a pair of power transmission electrodes, and power supplied from the high-frequency power supply section is transmitted to this power transmission electrode pair.
Multiple pairs of power transmission electrodes are connected in series, such that one power transmission electrode of one pair is connected in series with one power transmission electrode of an adjacent pair, and the other power transmission electrode is connected in series with the other power transmission electrode of the adjacent pair.
The power transmission device according to claim 1, characterized in that the phase advancement portion is provided in at least a portion of the space between adjacent pairs of power transmission electrodes connected in cascading. The phase advancement unit includes an inductor that works in cooperation with the capacitor to advance the phase of the high-frequency power.
The power transmission device according to claim 2, characterized in that the inductor is formed between a pair of power transmission electrodes provided on a predetermined power transmission electrode pair. The power transmission device according to claim 3, characterized in that the inductor is composed of a single coil, one end of which is connected to one of the pair of power transmission electrodes, and the other end of which is connected to the other of the pair of power transmission electrodes. Equipped with a ground plate maintained at a reference potential,
The aforementioned inductor is
A first coil, one end of which is connected to one of the pair of power-transmitting electrodes and the other end of which is connected to the ground plate,
The power transmission device according to claim 3, further comprising a second coil, one end of which is connected to the other of the pair of power transmission electrodes, and the other end of which is connected to the ground plate. The power transmission device according to claim 5, characterized in that the ground plate is formed on the side opposite to the side facing the receiving electrode with respect to the power transmission electrode forming layer, and includes a region that overlaps with the power transmission electrode when viewed from the receiving electrode side. The power transmission device according to claim 3, characterized in that the inductor is provided only for the power transmission electrode pair closest to and/or furthest from the high-frequency power supply unit, as a predetermined power transmission electrode pair. The power transmission device according to claim 3, characterized in that the inductor is composed of a printed pattern coil formed by a pattern printed on a printed circuit board. A contactless power supply system that supplies power to a load without contact,
A power transmission device according to any one of claims 1 to 8,
A contactless power supply system characterized by comprising a receiving electrode that receives power transmitted from the transmitting electrode of a power transmission device in a contactless manner using an electric field coupling method, and a receiving device that supplies the received power to the load.