WO2016125725A1 - Electric current detection element and electrical power transmission system - Google Patents

Abstract

The present invention is provided with a laminated body (10) wherein multiple insulation layers that include magnetic layers are layered, a main line electrode (11) formed in the laminated body (10) and a coil conductor (12) formed in the laminated body (10) that magnetically connects to the main line electrode (11). The laminated body (10) has a low magnetic permeability part (13) with a magnetic permeability lower than the surroundings thereof between the main line electrode (11) and the coil conductor (12). The low magnetic permeability part (13) contacts at least one of the main line electrode (11) and the coil conductor (12) and by doing so, allows for miniaturization, a current detection element that can detect current with good sensitivity and the provision of an electrical power transmission system that comprises said element.

Description

Current detection element and power transmission system

The present invention relates to a current detection element and a power transmission system for detecting a high-frequency current flowing in a line.

For example, a current transformer is known as an element for detecting a current flowing in a line. A current transformer is usually composed of a transformer wound around a toroidal core. For this reason, since the size of the parts increases, it may be difficult to use a current transformer in a device that is required to be small and low-profile. Therefore, as an example of a small and thin transformer, for example, there is a laminated transformer described in Patent Document 1. The laminated transformer described in Patent Document 1 is a surface-mount electronic component in which a magnetic sheet on which a conductor pattern is printed is laminated to constitute a transformer.

JP 2004-257964 A

However, in the case of the laminated transformer described in Patent Document 1, since the primary and secondary lines are substantially straight, the inductance is small and the coupling as a transformer is weak. For this reason, when this laminated transformer is used for current detection, the detection sensitivity may be low, and current detection may not be performed accurately.

Therefore, an object of the present invention is to provide a current detection element that can be downsized and detect current with high sensitivity, and a power transmission system including the current detection element.

A current detection element according to the present invention includes an insulator, a main line conductor formed on the insulator, and a current detection conductor formed on the insulator and magnetically coupled to the main line conductor. The insulator is provided between the main line conductor and the current detection conductor, and has a low permeability portion whose permeability is lower than that of the surroundings in the insulator.

In this configuration, when a current flows through the main line conductor, a magnetic flux is generated from the main line conductor, and the magnetic flux is linked to the current detection conductor, so that an induced current flows through the current detection conductor. By detecting this induced current, the current flowing through the main line conductor can be detected. Since the low magnetic permeability portion is formed between the main line conductor and the current detection conductor, the magnetic coupling between the main line conductor and the current detection conductor is strong. For this reason, the output voltage can be increased, and current detection can be performed with high sensitivity.

The main line conductor is preferably formed in a straight line in the insulator in plan view.

This configuration facilitates the formation of the main line conductor. Moreover, the inductance and resistance value of the main line conductor can be reduced. Moreover, the influence on the circuit connected to the main line can be reduced.

The coil for current detection may be a coiled conductor provided on the insulator and having a winding axis in a direction different from a direction in which the main line conductor extends.

In this configuration, the magnetic coupling between the main line conductor and the current detection conductor can be strengthened, and current detection can be performed with high sensitivity. Moreover, since it is a coiled conductor, the inductance of the detection conductor can be increased, and the output voltage increases.

The insulator is preferably a laminate in which a plurality of insulator layers having different magnetic permeability are laminated at least partially, and the plurality of insulator layers preferably have a magnetic layer at least partially.

In this configuration, the inductance of the current detection conductor can be increased, and the magnetic field generated by the current in the main line and the magnetic field around the current detection conductor can be confined in the substrate.

The magnetic layer is preferably a magnetic ferrite layer.

In this configuration, the inductance of the current detection conductor can be increased, and the magnetic field generated by the current in the main line and the magnetic field around the current detection conductor can be confined in the substrate. Further, the leakage magnetic field to the surroundings can be reduced, and the leakage noise can be reduced. Further, since the magnetic path can be formed of magnetic ferrite having a high magnetic permeability, the magnetic coupling between the main line conductor and the current detection conductor can be strengthened, and current detection can be performed with high sensitivity.

It is preferable that the low magnetic permeability portion is made of a nonmagnetic material.

In this configuration, it is possible to eliminate a state in which the magnetic field is confined in a region having a high magnetic permeability (around the main line or around the current detection conductor), so that the main line conductor, the current detection conductor, The magnetic field coupling can be strengthened, and the current can be detected with high sensitivity. Further, since the concentration of magnetic flux density can be relaxed, magnetic saturation of the magnetic material can be suppressed and a larger current can be handled.

The low magnetic permeability portion may be in contact with at least one of the main line conductor or the current detection conductor.

This configuration can weaken magnetic flux concentration.

It is preferable that the low magnetic permeability portion is in contact with the main line conductor and the current detection conductor.

In this configuration, it is possible to eliminate a state in which the magnetic field is confined in a region having a high magnetic permeability (around the main line or around the current detection conductor), so that the main line conductor, the current detection conductor, The magnetic field coupling can be strengthened, and the current can be detected with high sensitivity.

The current detection element according to the present invention may include a plurality of the current detection conductors.

In this configuration, when a plurality of current detection conductors are independent, a plurality of current detection results can be obtained. When a plurality of current detection conductors are connected in series, magnetic coupling between the main line conductor and the current detection conductor can be strengthened, and current detection can be performed with high sensitivity. When a plurality of current detection conductors are connected in parallel, the resistance of the current detection conductor can be lowered to suppress loss.

An element having a frequency characteristic connected to the current detection conductor may be provided.

In this configuration, the sensitivity in the frequency band to be used can be increased, and unnecessary frequency components (for example, harmonic components) can be filtered. In addition, since it is not necessary to externally attach an element having frequency characteristics, such as a capacitor, to the current detection element, it is not necessary to secure a region for mounting the element.

The present invention relates to power transmission for transmitting power from the power transmission device to the power reception device by coupling a power transmission side coupling unit of the power transmission device and a power reception side coupling unit of the power reception device by at least one of an electric field or a magnetic field. In the system, the power transmission device includes a current detection unit that detects a current having an AC component flowing in a power transmission line connected to the power transmission side coupling unit, and the current detection unit includes an insulator and the insulation A main line conductor formed in a body, and a current detection conductor formed in the insulator and magnetically coupled to the main line conductor, the insulator including the main line conductor and the current detection conductor And having a low magnetic permeability portion whose permeability is lower than that of the surroundings in the insulator, and the main line conductor constitutes a part of the power transmission line.

In this configuration, the current flowing through the power transmission side coupling unit can be detected with high sensitivity in the power transmission device. Based on the detected current magnitude or phase change, it is possible to determine whether or not the power receiving apparatus is mounted or to detect a state such as an abnormality.

According to the present invention, the magnetic field coupling between the main line conductor and the current detection conductor is strong. Therefore, current detection can be performed with high sensitivity.

1A is a plan view of the current detection element, and FIG. 1B is a cross-sectional view taken along the line II of FIG. 1A. 2A and 2B are diagrams illustrating a current detection circuit using a current detection element. 3A is a plan view of another example of the current detection element, and FIG. 3B is a cross-sectional view taken along line III-III in FIG. 3A. 4A is a plan view of the current detection element, and FIG. 4B is a cross-sectional view taken along line IV-IV in FIG. 4A. 5A is a plan view of the current detection element, and FIG. 5B is a cross-sectional view taken along line VV in FIG. 5A. FIG. 6 is a diagram for explaining the direction in which the induced current generated in the coil conductor flows. FIG. 7A, FIG. 7B, and FIG. 7C are diagrams showing another example of the current detection element. FIG. 8 is a diagram for explaining the effect of providing the low magnetic permeability portion. 9A is a plan view of a current detection circuit module including a current detection element, and FIG. 9B is a cross-sectional view taken along line IX-IX in FIG. 9A. FIG. 10 is a circuit diagram of the current detection circuit module. FIG. 11 is a circuit diagram of a power transmission system according to the fifth embodiment.

(Embodiment 1)
1A is a plan view of the current detection element 1, and FIG. 1B is a cross-sectional view taken along the line II in FIG. 1A. Note that the plan view shown in FIG. 1A is a perspective view.

The current detection element 1 includes a laminated body 10, a main line electrode 11, and a coil conductor 12. The laminate 10 is an insulator in which a plurality of insulator layers are laminated, and is formed by sintering. The insulator layer includes an insulator layer made of only a magnetic material such as ferrite, and an insulator layer made of a magnetic material and a non-magnetic material. The magnetic body is a ferromagnetic body and has a relative magnetic permeability μ _r > 1. The nonmagnetic material has a lower magnetic permeability than the surrounding magnetic material, and the relative magnetic permeability μ _r = 1. When these insulator layers are laminated, the laminated body 10 is formed with a high magnetic permeability portion made of a magnetic material and a low magnetic permeability portion 13 having a lower magnetic permeability than a surrounding high magnetic permeability portion made of a non-magnetic material. . Note that the low permeability portion 13 may be a non-magnetic material instead of a non-magnetic material (non-isomagnetic permeability μ _r ≠ 1, but lower than the permeability of the high permeability portion).

A plurality of mounting electrodes (not shown) for mounting on the mother board are formed on one main surface of the laminate 10. The current detection element 1 is mounted with the main surface (hereinafter referred to as a mounting surface) of the laminated body 10 on which the mounting electrodes are formed facing the mother substrate. FIG. 1A is a plan view seen from a surface (hereinafter referred to as an upper surface) facing the mounting surface in the stacking direction of the stacked body 10.

The main line electrode 11 is formed in the low permeability portion 13 of the laminate 10. The main line electrode 11 is a main surface of an insulating layer containing a nonmagnetic material, and is formed by printing a linear conductor pattern on the nonmagnetic material portion. A coil conductor 12 is disposed adjacent to the main line electrode 11. Each of the vicinity of both ends of the main line electrode 11 in the direction intersecting with the arrangement direction of the coil conductor 12 and the main line electrode 11 is connected to a different mounting electrode via an interlayer connection conductor (black circle in the figure). The main line electrode 11 is an example of the “main line conductor” according to the present invention. Since the main line electrode 11 is formed in a straight line, the main line electrode 11 can be easily formed, and the inductance and the resistance value of the main line electrode 11 can be reduced.

Note that the main line electrode 11 can be drawn out to the side surface parallel to the stacking direction of the multilayer body 10 and connected to the mounting electrode via the side surface of the multilayer body 10. In this case, the area where the main line electrode 11 is in contact with or close to the magnetic body in the laminated body 10 can be shortened, and the effective magnetic permeability due to the magnetic body and the non-magnetic body around the main line electrode 11 is reduced. Therefore, the inductance of the main line electrode 11 can be further reduced.

The coil conductor 12 is formed so that the winding axis is in the stacking direction of the stacked body 10 and a part thereof is positioned in the low magnetic permeability portion 13. The winding axis of the coil conductor 12 faces a direction different from the direction in which the main line electrode 11 extends. That is, the winding axis of the coil conductor 12 has a twisted positional relationship with the main line electrode 11. The coil conductor 12 is disposed adjacent to the main line electrode 11 with a gap in plan view from the stacking direction. The coil conductor 12 is an example embodiment that corresponds to the “current detection conductor” according to the present invention. Note that the winding direction of the coil conductor 12 is not particularly limited. A plurality of coil conductors may be arranged along the direction in which the main line electrode 11 extends.

The coil conductor 12 is composed of open loop conductors 121, 122, 123, and 124. Each of the open loop conductors 121, 122, 123, and 124 is formed on a main surface of a different insulator layer. Further, the open loop conductors 122 and 123 are formed on the main surface of the insulator layer including the nonmagnetic material, and a part of the open loop conductors 122 and 123 is formed in the nonmagnetic material portion. And one end of the open loop-shaped conductor adjacent to the lamination direction is connected by the interlayer connection conductor (not shown). As a result, the coil conductor 12 is formed in which the winding axis is in the stacking direction of the stacked body 10 and a part thereof is disposed in the low magnetic permeability portion 13 of the stacked body 10.

Note that both ends of the coil conductor 12 are connected to different mounting electrodes formed on the mounting surface of the multilayer body 10 by interlayer connection conductors (not shown).

In the current detecting element 1 having this configuration, when a current having an AC component flows through the main line electrode 11, a magnetic flux that changes with time is generated. Since the winding axis of the coil conductor 12 has a torsional positional relationship with the current flowing through the main line electrode 11, the coil conductor 12 has a current flowing through the coil opening of the coil conductor 12 and the current flowing through the main line electrode 11. The generated magnetic flux interlinks. Thereby, the main line electrode 11 and the coil conductor 12 are magnetically coupled. An induced electromotive force is generated in the coil conductor 12, and an induced current flows through the coil conductor 12 in accordance with the induced electromotive force. By detecting this induced electromotive force or induced current, the current flowing through the main line electrode 11 can be detected.

In the present embodiment, the main line electrode 11 and a part of the coil conductor 12 are formed in the low magnetic permeability portion 13. In other words, the low magnetic permeability portion 13 is formed between the main line electrode 11 and the coil conductor 12 in a plan view in the winding axis direction of the coil conductor 12 shown in FIG. The main line electrode 11 and a part of the coil conductor 12 are in contact with the low magnetic permeability portion 13. For this reason, since the magnetic flux generated from the main line electrode 11 passes through the coil opening of the coil conductor 12 so as to avoid the space between the main line electrode 11 and the coil conductor 12, the coil conductor 12 Many magnetic fluxes are linked. As a result, the magnetic field coupling between the main line electrode 11 and the coil conductor 12 is strengthened. Thereby, the detection sensitivity of the electric current which flows into the electrode 11 for main lines can be improved. Further, since only a part of the coil conductor 12 is formed in the low magnetic permeability portion 13, the inductance of the coil conductor 12 is not significantly reduced by the low magnetic permeability portion 13.

Further, by providing the low magnetic permeability portion 13 between the main line electrode 11 and the coil conductor 12, magnetic field coupling can be strengthened without reducing the distance between the main line electrode 11 and the coil conductor 12. . Then, by separating the main line electrode 11 and the coil conductor 12, the parasitic capacitance generated between the two electrodes can be reduced.

Furthermore, since the main line electrode 11 is disposed in the low magnetic permeability portion 13, the magnetic flux concentration in the vicinity of the main line electrode 11 can be weakened. For this reason, a larger current can flow through the main line electrode 11. Since the magnetic permeability around the main line electrode 11 is low, the inductance component or magnetic loss of the main line electrode 11 can be reduced. Furthermore, magnetic saturation around the main line electrode 11 can be prevented.

FIG. 2A and FIG. 2B are diagrams showing a current detection circuit using the current detection element 1. The inductor L1 shown in FIGS. 2A and 2B is an inductance component of the main line electrode 11.

The current detection element 1 is mounted on the mother board so that the main line electrode 11 is arranged in the middle of the main line of the mother board. The mounting electrode to which the coil conductor 12 is connected is connected to a detection circuit for detecting a current flowing through the main line electrode 11. As shown in FIG. 2A, the detection circuit is a capacitor C1 and a load RL. By mounting the current detection element 1 on the mother board, the coil conductor 12 is connected in series to the capacitor C1 and the load RL. As described above, when an induced current flows through the coil conductor 12, the current flowing through the main line electrode 11, that is, the current flowing through the main line of the mother board is detected by detecting the voltage across the load RL. it can. The capacitor C1 is connected in series to the coil conductor 12, but may be connected in parallel.

2A, the capacitor C1 is externally connected to the current detection element 1. However, as shown in FIG. 2B, the capacitor C2 may be provided in the current detection element 1. Good. The capacitor C2 can be formed, for example, by being mounted on the upper main surface of the multilayer body 10 or by disposing two planar conductors in parallel in the multilayer body. The capacitor C2 and the load RL constitute a detection circuit. In this case, since it is not necessary to externally attach the capacitor C2 to the current detection element 1, it is not necessary to secure a region for mounting the capacitor C2 on the mother board. The capacitor C2 is an example of the “element having frequency characteristics” according to the present invention.

In addition, the low magnetic permeability part 13 should just overlap with at least one of the electrode 11 for main lines, and the coil conductor 12 by planar view.

3A is a plan view of another example of the current detection element 1A, and FIG. 3B is a cross-sectional view taken along line III-III in FIG. 3A. Note that the plan view shown in FIG. 3A is a perspective view.

In this example, only the main line electrode 11 is formed in the low magnetic permeability portion 13A. Even in this configuration, since the low magnetic permeability portion 13A is formed between the main line electrode 11 and the coil conductor 12, the main line electrode 11 is compared with the case where the low magnetic permeability portion 13 is not formed. Magnetic field coupling between the coil conductor 12 and the coil conductor 12 can be strengthened. For this reason, the detection sensitivity of the electric current which flows into the electrode 11 for main lines can be improved.

In the current detection elements 1 and 1A, the main line electrode 11 is entirely formed in the low magnetic permeability portions 13 and 13A, but a part of the main line electrode 11 is formed in the low magnetic permeability portions 13 and 13A. It only has to be formed. Further, in the current detection element 1A, the low magnetic permeability portion 13A overlaps with the main line electrode 11 in a plan view in the winding axis direction of the coil conductor 12, but overlaps with the coil conductor 12, and the main line electrode 11 The structure may not overlap. Further, the low magnetic permeability portions 13 and 13A do not overlap with the coil conductor 12 and the main line electrode 11, but have low magnetic permeability on a line segment connecting a part of the coil conductor 12 and a part of the main line electrode 11. The structure by which the parts 13 and 13A are arrange | positioned may be sufficient. Even in this configuration, the magnetic coupling between the main line electrode 11 and the coil conductor 12 is stronger than in the case where the low magnetic permeability portions 13 and 13A are not formed. Therefore, the detection sensitivity of the current flowing through the main line electrode 11 is high. Can be increased.

However, when at least one of the coil conductor 12 and the main line electrode 11 is in contact with the non-magnetic part, the non-magnetic part is not in contact with both the coil conductor 12 and the main line electrode 11. The bond can be increased more than the case. In this case, most of the magnetic flux passing through the high magnetic permeability portion can be linked to one of the coil conductor 12 and the main line electrode 11, and is generated in the high magnetic permeability portion. Leakage magnetic flux not interlinked with one of the two can be reduced. Furthermore, when both the coil conductor 12 and the main line electrode 11 are in contact with the non-magnetic part, at least one of the coil conductor 12 and the main line electrode 11 is in contact with the non-magnetic part. Bonding can be increased over the absence. In this case, most of the magnetic flux passing through the high magnetic permeability portion can be linked to both the coil conductor 12 and the main line electrode 11, and is generated in the high magnetic permeability portion, so that the coil conductor 12 and the main line electrode 11 are connected. Leakage magnetic flux not interlinking with both can be reduced.

In the present embodiment, the high permeability portion is a magnetic material (ferromagnetic material), the low permeability portion is a non-magnetic material, or a magnetic material having a lower permeability than the high permeability portion. However, the present invention is not limited to this. For example, the low magnetic permeability portion may be formed of a diamagnetic material (relative magnetic permeability μ _r <1), and the high magnetic permeability portion may be formed of a magnetic material or a nonmagnetic material. It is sufficient that at least the permeability of the low permeability portion is lower than the permeability of the surrounding high permeability portion.

In the stacking direction, the outermost two layers of the stacked body 10 may be nonmagnetic layers, and the outermost two nonmagnetic layers may sandwich the magnetic layer and another nonmagnetic layer. Thereby, while confining a magnetic flux in the laminated body 10, the mechanical strength of the laminated body 10 can be strengthened.

(Embodiment 2)
The current detection element according to the second embodiment is different from the first embodiment in the size of the low magnetic permeability portion.

4A is a plan view of the current detection element 2, and FIG. 4B is a cross-sectional view taken along the line IV-IV in FIG. 4A. Note that the plan view shown in FIG. 4A is a perspective view.

The laminated body 10A of the current detection element 2 is configured by laminating and sintering an insulator layer made of only a ferromagnetic material such as ferrite and an insulator layer made of only a nonmagnetic material. By laminating the insulator layer made of only the nonmagnetic material, the low magnetic permeability portion 14 of the nonmagnetic material layer is formed in the laminated body 10A. And the insulator layer which consists only of a ferromagnetic material is laminated | stacked so that the low magnetic permeability part 14 may be pinched | interposed along the lamination direction.

The main line electrode 11 is formed on the main surface of an insulator layer made of only a non-magnetic material. The coil conductor 12 is formed by connecting open loop conductors 121, 122, 123, and 124 with interlayer connection conductors (not shown) so that the winding axis is in the stacking direction of the stacked body 10A. The open loop conductors 122 and 123 are formed on the main surface of the insulator layer made of only a nonmagnetic material. Thereby, a part of the main line electrode 11 and the coil conductor 12 is formed in the low magnetic permeability portion 14 of the laminated body 10A.

In addition, since the current detection method by the current detection element 2 is the same as that of the first embodiment, the description is omitted.

As in this configuration, by arranging the main line electrode 11 in the laminated body 10A, the magnetic flux concentration in the vicinity of the main line electrode 11 can be weakened, and a larger current can flow. Further, the magnetic field coupling between the main line electrode 11 and the coil conductor 12 can be strengthened. Thereby, the detection sensitivity of an electric current can be raised. Furthermore, since the magnetic permeability around the main line electrode 11 is low, the inductance component or magnetic loss of the main line electrode 11 can be reduced. In addition, magnetic saturation around the main line electrode 11 can be prevented.

(Embodiment 3)
The current detection element according to the third embodiment is different from the first embodiment in that it includes two coil conductors for detecting current.

5A is a plan view of the current detection element 3, and FIG. 5B is a cross-sectional view taken along line VV in FIG. 5A.

The current detection element 3 includes a laminate 20, a main line electrode 21, and coil conductors 22A and 22B. The laminated body 10 is formed by laminating and sintering a plurality of insulator layers. The insulator layer includes an insulator layer made of only a ferromagnetic material such as ferrite, and an insulator layer made of a ferromagnetic material and a non-magnetic material. When these insulator layers are laminated, a low magnetic permeability portion 24 having a lower magnetic permeability than the surroundings is formed in the laminated body 20 by the nonmagnetic material.

The main line electrode 21 is formed in the low permeability portion 24 of the laminate 20. The main line electrode 21 is an example embodiment that corresponds to the “main line conductor” according to the present invention.

The coil conductors 22A and 22B are formed such that the winding axis is in the stacking direction of the stacked body 20 and the main line electrode 21 is sandwiched between them in a plan view from the stacking direction. The winding axis of the coil conductors 22A and 22B is directed in a direction different from the direction in which the main line electrode 21 extends. That is, the winding axes of the coil conductors 22A and 22B are in a torsional positional relationship with the main line electrode 21, respectively. The coil conductors 22A and 22B are examples of the “current detection conductor” according to the present invention.

The coil conductor 22A is formed by connecting open loop conductors 221, 222, 223, and 224 formed on the main surfaces of different insulator layers through interlayer connection conductors (not shown). A part of the coil conductor 22 </ b> A is located in the low magnetic permeability portion 24. In the case of FIGS. 5A and 5B, the open loop conductors 222 and 223 are formed on the main surface of the insulator layer including the nonmagnetic material, and a part of the open loop conductors 222 and 223 is formed. It is formed in the non-magnetic part. Thereby, a part of the coil conductor 22 </ b> A is formed in the low magnetic permeability portion 24 of the multilayer body 20.

The coil conductor 22B is formed by connecting open loop conductors 225, 226, 227, and 228 formed on the main surfaces of different insulator layers through interlayer connection conductors (not shown). The open loop conductors 225, 226, 227, and 228 may be formed in the same layer as the insulator layer in which the open loop conductors 221 to 224 are formed, or may be formed in different layers. A part of the coil conductor 22 </ b> B is located in the low magnetic permeability portion 24. In the case of FIGS. 5A and 5B, the open loop conductors 226 and 227 are formed on the main surface of the insulator layer including the nonmagnetic material, and a part of the open loop conductors 226 and 227 is formed. It is formed in the non-magnetic part. Thereby, a part of the coil conductor 22 </ b> B is formed in the low magnetic permeability portion 24 of the multilayer body 20.

One end of the coil conductors 22A and 22B on the mounting surface side is connected to the mounting electrode by an interlayer connection conductor. Further, one end on the upper surface side of the coil conductors 22A and 22B is connected by a connection conductor 23. The connection conductor 23 is formed on the main surface of the insulator layer so as to straddle the main line electrode 21. The coil conductors 22A and 22B are connected in series by the connection conductor 23, so that the coil conductors 22A and 22B form one coil.

In addition, when the connection conductor 23 is formed in a layer away from the main line electrode 11, the parasitic capacitance between the connection conductor 23 and the main line electrode 21 can be reduced.

FIG. 6 is a diagram for explaining the direction in which the induced current generated in the coil conductors 22A and 22B flows.

When a current flows through the main line electrode 21, a magnetic flux is generated, and the magnetic flux passes through the coil openings of the coil conductors 22A and 22B, so that the main line electrode 21 and the coil conductors 22A and 22B are magnetically coupled. More specifically, one of the coil conductors 22A and 22B is interlinked with the magnetic flux by the main line electrode 21 from the upper surface side in the stacking direction to the mounting surface side, and the other is for the main line from the mounting surface side to the upper surface side. Magnetic flux from the electrode 21 is linked. When the main line electrode 21 and the coil conductors 22A and 22B are magnetically coupled, an induced electromotive force is generated in the coil conductors 22A and 22B, and an induced current flows in the coil conductors 22A and 22B according to the induced electromotive force.

The direction in which the induced current generated in the coil conductors 22A and 22B flows is reverse when the main line electrode 21 and the coil conductors 22A and 22B are viewed in a plan view from the stacking direction. Here, the coil conductor 22A and the coil conductor 22B are connected so that the induced currents flowing through the coil conductors 22A and 22B do not cancel each other. That is, if the coil conductors 22A and 22B are both left-handed helix, the coil conductors 22A and 22B are connected in series by connecting one end on the upper surface side. Therefore, the magnetic field coupling between the main line electrode 11 and the coil conductors 22A and 22B is not weakened.

In this embodiment, the coil conductors 22A and 22B are both left-handed, that is, in the same winding direction, and the coil conductors 22A and 22B are connected in series by connecting one end on the upper surface side to each other. The magnetic flux generated by the current flowing through the line electrode 21 passes through the coil openings of the coil conductors 22A and 22B, and the main line electrode 21 and the coil conductors 22A and 22B are magnetically coupled. , 22B is not limited to this structure and connection method.

The winding direction and connection method of the structure of the coil conductors 22A and 22B are set so that the induced currents generated in the coil conductors 22A and 22B are not canceled by the magnetic field coupling between the main line electrode 21 and the coil conductors 22A and 22B. select. First, in order to determine the winding direction of the structure of the coil conductors 22A and 22B in plan view from the stacking direction, the winding start and the winding end are arbitrarily determined at the two ends of the coil conductors 22A and 22B. If the winding direction from the winding start to the winding end of the structure of the coil conductors 22A and 22B is the same in a plan view from the lamination direction, one winding start and the other winding start of the coil conductors 22A and 22B Are connected, or one winding end and the other winding end are connected, and the coil conductors 22A and 22B are connected in series. If the winding directions from the winding start to the winding end of the structure of the coil conductors 22A and 22B are opposite to each other in plan view from the lamination direction, one winding start and the other winding end of the coil conductors 22A and 22B Are connected, and the coil conductors 22A and 22B are connected in series.

As described above, in the current detection element 3, when a current flows through the main line electrode 21, the main line electrode 21 and the coil conductors 22A and 22B are magnetically coupled. As described in the first embodiment, an induced current flows through the coil conductors 22A and 22B. By detecting this induced current, the current flowing through the main line electrode 21 can be detected.

In the present embodiment, the main line electrode 21 and part of the coil conductors 22A and 22B are formed in the low magnetic permeability portion 24. In other words, the low magnetic permeability portion 24 is formed between the main line electrode 21 and the coil conductors 22A and 22B in a plan view shown in FIG. For this reason, the magnetic field coupling between the main line electrode 21 and the coil conductors 22A and 22B becomes stronger than when the low magnetic permeability portion is not formed. Thereby, the detection sensitivity of the electric current which flows into the electrode 21 for main lines can be improved.

The main line electrode 21 is disposed between the coil conductors 22A and 22B. For this reason, when the laminated body 20 is manufactured by laminating the insulator layers, even if the distance between the main line electrode 21 and the coil conductor 22A is increased, the main line electrode 21 and the coil conductor 22B The distance of approaches. That is, even if the magnetic field coupling between the main line electrode 21 and the coil conductor 22A becomes weak, the magnetic field coupling between the main line electrode 21 and the coil conductor 22B becomes strong. The coil conductors 22A and 22B are connected in series to form one coil conductor. Therefore, even if the lamination deviation of the ferrite sheet occurs, the magnetic field coupling between the main line electrode 21 and the two coil conductors 22A and 22B is not substantially changed.

In addition, the formation area of the low magnetic permeability part 24 is not limited to FIG.

7A, 7B, and 7C are diagrams showing current detection elements 3A, 3B, and 3C of another example.

In the current detection element 3 </ b> A shown in FIG. 7A, two low magnetic permeability portions 24 </ b> A and 24 </ b> B are formed in the laminate 20. The low magnetic permeability portions 24A and 24B correspond to “low magnetic permeability portions” according to the present invention. The low magnetic permeability portion 24A is in contact with a part of the main line electrode 21 and a part of the coil conductor 22A. The low magnetic permeability portion 24B is in contact with a part of the main line electrode 21 and a part of the coil conductor 22B. Even in this configuration, since the low magnetic permeability portions 24A and 24B are formed between the main line electrode 21 and the coil conductors 22A and 22B, the magnetic field between the main line electrode 21 and the coil conductors 22A and 22B. The coupling is strong, and the detection sensitivity of the current flowing through the main line electrode 21 can be increased.

7B has a layer of a low magnetic permeability portion 24C in part. The laminated body 20 of the current detection element 3B shown in FIG. The layers other than the low magnetic permeability portion 24C are ferromagnetic layers. The main line electrode 21 and the open loop conductors 222, 223, 226, and 227 are formed in the low magnetic permeability portion 24C. Even in this configuration, the magnetic coupling between the main line electrode 21 and the coil conductors 22A and 22B is strong, and the detection sensitivity of the current flowing through the main line electrode 21 can be increased.

In the current detection element 3C shown in FIG. 7C, the main line electrode 21 has a multilayer structure in which a plurality of electrodes (two electrodes in the figure) are connected by an interlayer connection conductor (not shown). The electrode 21 is disposed in the low magnetic permeability portion 24D. By making the main line electrode 21 have a multilayer structure, the inductance component and resistance component of the main line electrode 21 can be reduced. Further, by disposing the main line electrode 21 in the low magnetic permeability portion 24D, the magnetic flux density generated in the laminate 20 by the current flowing through the main line electrode 21 can be reduced (the magnetic flux concentration is weakened). it can. As a result, saturation of the magnetic layer can be prevented, so that a larger current can be passed through the main line electrode 21.

The low magnetic permeability portion 24D is formed to be thicker than the thickness of the magnetic layer sandwiching the low magnetic permeability portion 24D from above and below. At this time, if the thickness of the magnetic layer is reduced, the magnetic flux density is likely to be saturated (non-linearity) within the layer. Therefore, the magnetic layer is preferably formed with a thickness that allows the internal magnetic flux density to be allowed. . The relative magnetic permeability of the magnetic layer is, for example, 50 to 300.

The coil conductors 22A and 22B include the coil conductors 22Au and 22Bu formed in the upper magnetic layer in the stacking direction with the low permeability portion 24D interposed therebetween, and the coil conductors 22Ad and 22Bu formed in the lower magnetic layer. 22Bd. The distance between the coil conductor 22Au and the coil conductor 22Ad is longer than the distance between the coil conductors 22Au adjacent to each other in the stacking direction or the distance between the coil conductors 22Ad. Further, the distance between the coil conductor 22Bu and the coil conductor 22Bd is longer than the distance between the coil conductors 22Bu adjacent to each other in the stacking direction or the distance between the coil conductors 22Bd. The lower part of the coil conductors 22Au and 22Bu and the upper part of the coil conductors 22Ad and 22Bd are formed in the low magnetic permeability portion 24D. By forming the coil conductors 22A and 22B in the magnetic layer, the inductance of the coil conductors 22A and 22B is increased, so that the current detection sensitivity is increased. Further, since the magnetic layer is disposed so as to sandwich the main line electrode 21 and the coil conductors 22A and 22B, the magnetic coupling is strengthened, and the current detection sensitivity is increased.

Further, although the effect of contributing to the magnetic field coupling between the coil conductors 22Au and 22Ad formed in the low magnetic permeability portion 24D and the main line conductor is small, a loss occurs. For this reason, the coil conductor 22Au and the coil conductor 22Ad are spaced apart. Further, by separating the coil conductor 22Au and the coil conductor 22Ad, the coil conductor 22Au and the coil conductor 22Ad are also separated from the main line electrode 21, so that the parasitic between the coil conductors 22Au and 22Ad and the main line electrode 21 occurs. Generation of capacity can be prevented. Further, an insulation distance can be maintained between the coil conductors 22Au and 22Ad and the main line electrode 21. For the same reason, the coil conductor 22Bu and the coil conductor 22Bd are also separated from each other.

Further, the main line electrode 21 and the coil conductors 22A and 22B are formed so as not to overlap in the plane direction of the multilayer body 20 (a direction orthogonal to the lamination direction). Thereby, the main line electrode 21 and the coil conductors 22A and 22B are not close to each other, and the parasitic capacitance generated between the main line electrode 21 and the coil conductors 22A and 22B can be reduced. As a result, an error in the output voltage of the current detection circuit can be reduced.

FIG. 8 is a diagram for explaining the effect of providing the low magnetic permeability portion.

8 represents the coupling coefficient between the main line electrode and the coil conductor. The coupling coefficient is defined as k = M / √ (L1 × L2) where L1 is the inductance of the main line electrode, L2 is the inductance of the coil conductor, and M is the mutual inductance between the main line electrode and the coil conductor. To do. (1) is a current detection element not provided with a low permeability part, (2) is a current detection element 3A shown in FIG. 7A, (3) is a current detection element 3 shown in FIG. The coupling coefficients of the current detection element 3B shown in FIG. As can be seen from this figure, it can be seen that the provision of the low magnetic permeability portion increases the coupling coefficient as compared with the current detection element not provided with the low magnetic permeability portion.

In the present embodiment, the coil conductors 22A and 22B may be connected in parallel and connected in series. By connecting the coil conductors 22A and 22B in parallel, the resistance can be lowered and the loss can be suppressed. The winding direction and connection method of the coil conductors 22A and 22B when the coil conductors 22A and 22B are connected in parallel are as follows. If the winding direction from the winding start to the winding end of the structure of the coil conductors 22A and 22B is the same in plan view from the lamination direction, one winding start and the other winding end are connected, and And the other winding start are connected, and the detection circuit is connected between the two connection portions of the coil conductors 22A and 22B. If the winding directions from the winding start to the winding end of the structure of the coil conductors 22A and 22B are opposite to each other in plan view from the lamination direction, one winding start and the other winding start of the coil conductors 22A and 22B Are connected, and the end of one winding and the end of the other winding are connected, and a detection circuit is connected between the two connection portions of the coil conductors 22A and 22B.

Further, the coil conductors 22A and 22B may be independent from each other without being connected. In this case, the winding direction of the coil conductors 22A and 22B is not limited. Further, two current detection results can be obtained from each of the coil conductors 22A and 22B.

(Embodiment 4)
In the fourth embodiment, a mounting electrode for mounting an element used for current detection is provided on the upper surface of the current detection element, and the element is mounted on the mounting electrode to constitute a current detection circuit module.

FIG. 9A is a plan view of the current detection circuit module 4 provided with a current detection element, and FIG. 9B is a cross-sectional view taken along line IX-IX in FIG. 9A. FIG. 10 is a circuit diagram of the current detection circuit module 4. In FIG. 10, the power supply and bias circuit of the comparator U1 are omitted.

The current detection circuit module 4 includes a laminated body 30. The laminated body 30 is configured by laminating an insulating layer made of a ferromagnetic material such as ferrite and an insulating layer made of a non-magnetic material and sintering them. By laminating the insulating layers made of nonmagnetic material, the low magnetic permeability portions 31A, 31B, and 31C of the nonmagnetic material layer are formed in the laminated body 30. Further, insulator layers 32A and 32B made of a ferromagnetic material are stacked so as to be sandwiched between the low magnetic permeability portions 31A and 31B and the low magnetic permeability portions 31A and 31C along the stacking direction.

The mounting surface of the laminate 30 is provided with mounting electrodes 33A, 33B and the like for mounting on the mother board. On the upper surface of the laminate 30, mounting electrodes 34A, 34B, 34C, 34D, 34E and the like for mounting elements are provided. Although FIG. 9 illustrates the mounting electrodes 33A and 33B and the mounting electrodes 34A to 34E, the number of mounting electrodes is not limited to this.

The main surface of the insulator layer 32A is provided with a ground electrode 16 extending in a planar shape. The mounting electrode 34A is electrically connected to the ground electrode 16 through the interlayer connection conductor. The low magnetic permeability portion 31B is provided with a wiring pattern 17 that connects the mounting electrodes 34B to 34E.

The main line electrode 11 is formed in the low magnetic permeability portion 31A. The coil conductor 12 is formed in the insulator layers 32A and 32B and the low magnetic permeability portion 31A so that the winding axis is in the stacking direction of the stacked body 30. The winding axis of the coil conductor 12 faces a direction different from the direction in which the main line electrode 11 extends. That is, the winding axis of the coil conductor 12 has a twisted positional relationship with the main line electrode 11.

The mounting electrodes 34A to 34E are mounted with a comparator U1, a diode D1, capacitors C31, C32, C33, a resistor R1, and the like. The diode D1, the capacitors C31 and C32, and the resistor R1 constitute a detection circuit that detects the current flowing through the main line electrode 11, as in FIG. The capacitor C33 and the comparator U1 constitute a zero cross detection circuit. The zero cross detection circuit is a circuit that detects a zero point (zero cross point) of the AC voltage induced in the coil conductor 12, and outputs Hi when the AC voltage exceeds a specific potential (for example, ground potential). Output Lo when not. That is, a digital signal synchronized with the frequency is output.

In this configuration, the ground electrode 16 is provided so as to overlap the main line electrode 11 and the coil conductor 12. Thereby, electromagnetic field noise generated from the main line electrode 11 and the like is shielded by the ground electrode 16, and the influence on the elements (comparator U1 and the like) mounted on the upper surface of the multilayer body 30 is reduced. Further, by mounting necessary elements on the upper surface of the laminate 30, the mounting area of the current detection circuit module 4 can be saved.

The configuration of the stacked body 30 may be the configuration of the stacked body described in the first to third embodiments. For example, the low magnetic permeability portion may be formed in a part of the laminated body as shown in FIG. Moreover, the current detection circuit module 4 may include two coil conductors as described in the third embodiment.

(Embodiment 5)
In this example, a power transmission system including the current detection element 1 described in the first embodiment will be described.

FIG. 11 is a circuit diagram of the power transmission system 100 according to the fifth embodiment. The power transmission system 100 includes a power transmission device 101 and a power reception device 201. The power transmission system 100 transmits power from the power transmission apparatus 101 to the power reception apparatus 201 by a magnetic field coupling method.

The power receiving apparatus 201 includes a load circuit 211. The load circuit 211 includes a charging circuit and a secondary battery. Note that the secondary battery may be detachable from the power receiving apparatus 201. And the power receiving apparatus 201 is a portable electronic device provided with the secondary battery, for example. Examples of portable electronic devices include cellular phones, PDAs (Personal Digital Assistants), portable music players, notebook PCs, and digital cameras. The power transmission device 101 is a charging stand for charging the secondary battery of the power receiving device 201 placed thereon.

The power transmission apparatus 101 includes a DC power source Vin that outputs a DC voltage. The DC power source Vin is an AC adapter connected to a commercial power source. An inverter circuit 111 that converts a DC voltage into an AC voltage is connected to the DC power source Vin. A resonance circuit composed of capacitors C31 and C32 and a coil L2 is connected to the output side of the inverter circuit 111.

Further, the current detection element 1 is provided between the inverter circuit 111 and the resonance circuit. The main line electrode 11 of the current detection element 1 is a part of the power transmission line between the inverter circuit 111 and the resonance circuit. The current detection element 1 is mounted on a mother board (not shown) and connected to the capacitor C1 and the load RL. As described with reference to FIG. 2, by detecting the voltage of the load RL, a current flowing between the inverter circuit 111 and the resonance circuit (hereinafter referred to as a power transmission current) can be detected.

The power receiving apparatus 201 includes a capacitor C4 and a coil L3 that form a resonance circuit. The coils L2 and L3 are magnetically coupled to transmit power from the power transmitting apparatus 101 to the power receiving apparatus 201. The resonance circuit of the power receiving device 201 is set to the same resonance frequency as the resonance circuit of the power transmission device 101. By making the resonance frequencies of the resonance circuits of the power transmission apparatus 101 and the power reception apparatus 201 the same, power transmission can be performed efficiently.

The power reception circuit 210 is connected to the resonance circuit of the power reception device 201. The power receiving circuit 210 rectifies and smoothes the voltage induced in the coil L3. In addition, the power receiving circuit 210 converts the rectified and smoothed voltage into a stabilized predetermined voltage and supplies it to the load circuit 211.

In the power transmission system 100, by detecting the power transmission current of the power transmission device 101 and the input voltage V1 to the resonance circuit of the power transmission device 101, the impedance of the inverter circuit 111 viewed from the power reception device 201 side can be detected. By detecting the impedance, for example, it can be determined whether or not the power receiving apparatus 201 is placed on the power transmitting apparatus 101. When the power receiving apparatus 201 is mounted on the power transmitting apparatus 101, the resonance circuit of the power transmitting apparatus 101 and the power receiving apparatus 201 is coupled, and a frequency peak due to complex resonance appears. And the presence or absence of mounting of the power receiving apparatus 201 can be determined by detecting the frequency characteristics of the impedance and detecting the presence or absence of a frequency peak.

Even when only the power transmission current of the power transmission device 101 is detected using the current detection element 1, the presence or absence of the power reception device 201 is detected or the state of an abnormality is detected based on a change in the magnitude or phase of the current. It can be performed.

In each of the first to fourth embodiments described above, the current detection conductor for detecting the current flowing through the main line electrode is a coiled conductor. However, any shape can be used as long as it is magnetically coupled to the main line electrode. Is not particularly limited. Further, each of the first to fourth embodiments can be appropriately combined.

In each of the first to fourth embodiments described above, the main line electrode and the current detection conductor are formed inside the insulator having the high magnetic permeability portion and the low magnetic permeability portion. Each of the detection conductors may be at least partially formed on the surface of the insulator. At least the main line electrode and the current detection conductor are fixed to the insulator, and a low permeability portion of the insulator is disposed between the main line electrode and the current detection conductor, and a high permeability is provided around the low permeability portion. What is necessary is just to arrange | position a magnetic part.

C1, C2, C31, C32, C33, C4 ... Capacitor D1 ... Diode L1 ... Inductor L2, L3 ... Coil R1 ... Resistance RL ... Load U1 ... Comparator Vin ... DC power supply 1, 1A, 2, 3, 3A, 3B, 3C ... Current detection element 4 ... Current detection circuit module 10, 10A ... Laminate 11 ... Main line electrode 12 ... Coil conductors 13, 13A, 14 ... Low magnetic permeability part 16 ... Ground electrode 17 ... Wiring pattern 20 ... Laminate 21 ... Main line electrodes 22A, 22B ... Coil conductors 22Ad, 22Au ... Coil conductors 22Bd, 22Bu ... Coil conductors 23 ... Connection conductors 24, 24A, 24B, 24C, 24D ... Low magnetic permeability portions 30 ... Laminated bodies 31A, 31B, 31C ... Low magnetic permeability portions 32A, 32B ... insulator layers 33A, 33B ... mounting electrodes 34A, 34B, 34C, 34D, 34E ... mounting Pole 100 ... Power transmission system 101 ... Power transmission device 111 ... Inverter circuits 121, 122, 123, 124 ... Open loop conductor 201 ... Power reception device 210 ... Power reception circuit 211 ... Load circuits 221, 222, 223, 224, 225, 226 227, 228 ... open loop conductor 222Ad ... coil conductor

Claims (11)

1. An insulator;
   A main line conductor formed in the insulator;
   A current detecting conductor formed on the insulator and magnetically coupled to the main line conductor;
   With
   The insulator is
   Provided between the main line conductor and the current detection conductor, and has a low permeability portion whose permeability is lower than the surroundings in the insulator.
   Current detection element.
2. The main line conductor is formed in a straight line when viewed in plan in the insulator,
   The current detection element according to claim 1.
3. The current detection conductor is:
   A coiled conductor provided on the insulator and having a winding axis in a direction different from a direction in which the main line conductor extends;
   The current detection element according to claim 1 or 2.
4. The insulator is a laminate in which a plurality of insulator layers having different magnetic permeability are laminated at least partially, and the plurality of insulator layers have a magnetic layer at least partially.
   The current detection element according to claim 1.
5. The magnetic layer is a layer of magnetic ferrite;
   The current detection element according to claim 4.
6. The low magnetic permeability part is made of a non-magnetic material,
   The current detection element according to claim 1.
7. The low magnetic permeability part is in contact with at least one of the main line conductor or the current detection conductor,
   The current detection element according to claim 1.
8. The low magnetic permeability part is
   In contact with the main line conductor and the current detection conductor,
   The current detection element according to claim 7.
9. Comprising a plurality of the current detection conductors,
   The current detection element according to claim 1.
10. An element having a frequency characteristic connected to the current detection conductor;
    The current detection element according to claim 1.
11. In the power transmission system for transmitting power from the power transmission device to the power reception device by coupling the power transmission side coupling unit of the power transmission device and the power reception side coupling unit of the power reception device by at least one of an electric field or a magnetic field,
    The power transmission device is:
    A current detection unit for detecting a current having an AC component flowing in a power transmission line connected to the power transmission side coupling unit;
    Have
    The current detector is
    An insulator;
    A main line conductor formed in the insulator;
    A current detecting conductor formed on the insulator and magnetically coupled to the main line conductor;
    With
    The insulator is
    Provided between the main line conductor and the current detection conductor, and has a low permeability portion whose permeability is lower than the surroundings in the insulator,
    The main line conductor constitutes a part of the power transmission line,
    Power transmission system.

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