Current sensor

Abstract

A current sensor 10 according to the present invention includes: a bus bar 12 through which a current to be measured flows; and a magnetic sensor 13 disposed so as to be capable of detecting a magnetic field generated by the bus bar 12. The current sensor 10 has a conductor 14 made of a non-magnetic material, and the conductor 14 is disposed on the opposite side from the bus bar 12 across the magnetic sensor 13. Thus, the present invention suppresses a problem with the frequency characteristic of a current sensor, wherein a measurement error increases due to the skin effect proportional to the frequency of a current to be measured flowing through the bus bar, leading to improved measurement accuracy.

Description

Current Sensor

[0001] The present invention relates to a current sensor that measures a current to be measured that flows through a bus bar.

[0002] In recent years, current sensors have been used to measure the current flowing through various devices in order to control the power supply systems of vehicles and other devices. Current sensors have a problem with frequency characteristics: when the current flowing through a bus bar is AC, measurement errors increase due to a skin effect proportional to the current frequency. Various studies have been conducted to improve this frequency characteristic problem. For example, Patent Document 1 describes a current sensor in which an insulating portion is provided in the primary conductor through which the current flows to suppress the generation of eddy currents, which cause the frequency characteristics. Patent Document 2 describes a current sensor in which a magnetoelectric transducer is disposed at a position that does not face each of multiple surfaces of a current path through which the current flows, and the sensitivity axis direction of the magnetoelectric transducer is parallel to the thickness direction of the current path. Patent Document 3 describes a current detection device in which a pair of magnetic sensing elements are disposed at asymmetric positions that avoid the center of the cross section of the conductor through which the current flows and are spaced apart from each other at different distances from the center of the cross section.

[0003] JP 2017-58275 A WO2018 / 142850 A JP 2022-52554 A

[0004] However, it is difficult to sufficiently suppress the problem of frequency characteristics in the current sensors and current detection devices described in Patent Documents 1 to 3. Therefore, an object of the present invention is to provide a current sensor with good measurement accuracy that suppresses the problem of frequency characteristics, in which measurement errors increase due to the skin effect, which is affected by the frequency of the current to be measured flowing through the bus bar.

[0005] As a means for solving the above-described problems, the present invention has the following configuration: A current sensor including a bus bar through which a current to be measured flows and a magnetic sensor arranged to be able to detect a magnetic field generated by the bus bar, the current sensor including a non-magnetic conductor arranged on the opposite side of the bus bar across the magnetic sensor. By placing the non-magnetic conductor on the opposite side of the bus bar across the magnetic sensor, it is possible to cancel at least a portion of the magnetic field caused by eddy currents that are generated in the bus bar when a current to be measured flows through the bus bar, thereby reducing the influence of the magnetic field caused by the eddy currents.

[0006] The direction in which the bus bar, the magnetic sensor, and the conductor are aligned is defined as a first direction, the direction in which the bus bar extends perpendicular to the first direction is defined as a second direction, and the direction perpendicular to the first and second directions is defined as a third direction. The conductor may be formed in a flat plate shape parallel to a plane formed by the second and third directions. In this case, when viewed along the first direction, it is preferable that the bus bar and the magnetic sensor are located inside each end of the conductor in the third direction. With the above configuration, eddy currents flowing in the opposite direction to eddy currents generated in the bus bar when a current to be measured flows through the bus bar are more likely to be generated in the conductor, thereby improving the frequency characteristics of the current sensor.

[0007] The non-magnetic material may be aluminum, which is lightweight and inexpensive, allowing a lightweight current sensor to be manufactured at low cost.

[0008] The current sensor may be provided with a magnetic shield, which can reduce magnetic noise and improve the measurement accuracy of the current sensor.

[0009] The magnetic shield may have a first magnetic shield plate having a flat plate shape, and the first magnetic shield plate may be disposed between the magnetic sensor and the conductor. With the above configuration, the magnetic shield can be disposed near the magnetic sensor, thereby improving the effect of reducing magnetic noise by the magnetic shield.

[0010] The magnetic shield may have a flat first magnetic shield plate and a flat second magnetic shield plate, and the magnetic sensor and the bus bar may be disposed between the first magnetic shield plate and the second magnetic shield plate. This configuration reduces magnetic noise in the magnetic sensor disposed between the first magnetic shield plate and the second magnetic shield plate, and prevents the second magnetic shield plate from interfering with measurement of a magnetic field generated when a current to be measured flows through the bus bar. This results in a current sensor with good measurement accuracy.

[0011] The magnetic shield may have a U-shape when viewed along the second direction, and may include sidewalls spaced apart from each other on both sides of the magnetic sensor and the bus bar in the third direction, and a bottom disposed on the opposite side of the magnetic sensor in the first direction across the bus bar. Using a U-shaped magnetic shield including a bottom and sidewalls can efficiently block magnetic noise from the third direction in addition to the first direction.

[0012] The current sensor may include a pair of magnetic sensors having opposite detection directions, and may detect the magnetic field emitted by the bus bar as a difference between the magnetic fields detected by the pair of magnetic sensors. By using the difference between the magnetic fields detected by the pair of magnetic sensors having opposite detection directions, magnetic noise can be reduced, thereby improving the measurement accuracy of the current sensor.

[0013] The current sensor of the present invention uses a non-magnetic conductor to reduce the effects of eddy currents that occur when an AC current flows through the bus bar. The reduction in the skin effect suppresses measurement errors due to the frequency of the current to be measured, thereby providing a current sensor with excellent measurement accuracy.

[0014] 1 is a perspective view showing the appearance of a current sensor according to a first embodiment; FIG. 2 is an exploded perspective view showing the configuration of the current sensor of FIG. 1; FIG. 3 is a cross-sectional view schematically showing the configuration of the current sensor of FIG. 1; FIG. 4 is an explanatory view schematically showing the skin effect; FIG. 5 is an explanatory view schematically showing a mechanism by which a conductor acts on a bus bar; FIG. 6 is a graph of phase characteristics of a conventional current sensor and the current sensor of the first embodiment; FIG. 7 is a cross-sectional view schematically showing the configuration of a current sensor according to a second embodiment; FIG. 8 is a cross-sectional view schematically showing a modified example of the current sensor of FIG. 7; FIG. 9 is a graph of phase characteristics of a conventional current sensor and the current sensor of the second embodiment; FIG. 10 is a graph showing the relationship between the distance between a conductor and a bus bar and the phase characteristics of the current sensor of the second embodiment; FIG. 11 is a plan view schematically showing the configuration of a current sensor according to a third embodiment; FIG. 12 is a plan view schematically showing a modified example of the current sensor of FIG. 11; and FIG. 13 is a plan view schematically showing another modified example of the current sensor of FIG. 11.

[0015] [First Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The same components in each drawing are assigned the same numbers, and their description will be omitted. Reference coordinates are shown in each drawing as appropriate to indicate the positional relationship of each component. In the reference coordinates, the width direction of the bus bar is defined as the X direction (third direction), the extension direction of the bus bar perpendicular to the X direction is defined as the Y direction (second direction), and the direction perpendicular to the X and Y directions is defined as the Z direction (first direction). The X direction is the direction of the sensitivity axis of the magnetic sensor, and the Y and Z directions are perpendicular to the sensitivity axis.

[0016] Fig. 1 is a perspective view showing the appearance of a coreless current sensor 10 according to this embodiment, Fig. 2 is an exploded perspective view showing the configuration of current sensor 10, and Fig. 3 is a cross-sectional view schematically showing the configuration of current sensor 10. As shown in these figures, current sensor 10 includes busbar 12, magnetic sensor 13, conductor 14, substrate 15, housing 16, and cover 17.

[0017] The bus bar 12 is a plate-shaped conductor made of copper, brass, aluminum, or the like, through which the current to be measured flows, and is provided in the housing 16 as shown in Figures 1 and 2. The bus bar 12 can be configured to be fixed to the housing 16 by insert molding, or can be configured to be attachable to the housing 16 by fitting into the housing 16, for example.

[0018] The housing 16 has a storage space that is open in the Z2 direction, and the substrate 15 on which the magnetic sensor 13 is attached is stored in the storage space. The substrate 15 is made of epoxy glass, ceramic, or the like, and is fixed to the housing 16 by a fixing member (not shown). In addition, a cover part 17 is disposed on the Z2 side of the housing 16 so as to close the opening of the storage space.

[0019] The magnetic sensor 13 is capable of detecting a magnetic field generated by the bus bar 12 when a current to be measured flows through it, and is disposed opposite the bus bar 12 in the Z direction. Note that when a current to be measured flows through the bus bar 12 in the configuration shown in Fig. 3, a magnetic field with a large X-direction component is generated on the Z2 side of the bus bar 12. Therefore, it is necessary to dispose the magnetic sensor 13 so that the detection surface of the magnetic sensor 13 faces the bus bar 12 directly and the sensitivity axis faces the X direction.

[0020] The magnetic sensor 13 of this embodiment uses a magnetoresistive element as a detection element. The surface of the magnetic sensor 13 facing the bus bar 12 is the detection surface, and the magnetic sensor 13 can detect magnetic components in a direction parallel to the detection surface. In other words, the sensitivity axis is oriented in a direction parallel to the detection surface. Therefore, by arranging the magnetic sensor 13 so that the detection surface of the magnetic sensor 13 faces the bus bar 12 directly and the sensitivity axis is oriented in the X direction, the induced magnetic field from the bus bar 12 can be detected with high accuracy. In addition to the magnetoresistive element, the magnetic sensor 13 can also use a Hall element or the like as a detection element. Note that the sensitivity axis direction with respect to the detection surface changes depending on the detection element used in the magnetic sensor 13, so the arrangement of the magnetic sensor 13 needs to be changed appropriately.

[0021] The conductor 14 is a non-magnetic material and is formed in a rectangular flat plate shape, as described below. The conductor 14 is disposed on the opposite side of the bus bar 12 in the Z direction, sandwiching the magnetic sensor 13 therebetween. Providing the non-magnetic conductor 14 reduces the influence of eddy currents that occur within the bus bar 12 when current flows through the bus bar 12, thereby improving the frequency characteristics of the current sensor 10. The reason for this will be explained separately. In the current sensor 10, the conductor 14 is disposed on the surface of the cover portion 17 on the Z2 side.

[0022] Many coreless current sensors include a flat magnetic shield plate as described in the second embodiment below. However, the magnetic shield plate is made of a magnetic material, while the conductor 14 is made of a non-magnetic material. Thus, the magnetic shield plate and the conductor 14 are completely different components in terms of whether they are made of a magnetic material or a non-magnetic material.

[0023] Here, "non-magnetic material" refers to, for example, copper (Cu), aluminum (Al), titanium (Ti), etc. In the present invention, any material other than a ferromagnetic material is referred to as a "non-magnetic material." Of the non-magnetic materials listed above, aluminum is preferred because it is lightweight and inexpensive, and is advantageous from the perspectives of weight reduction and manufacturing costs.

[0024] As shown in FIG. 2 , the conductor 14 is formed in a rectangular plate shape with the Y direction extending parallel to the XY plane defined by the X and Y directions. As shown in FIG. 3 , when viewed along the Z direction (first direction), the busbar 12 and the magnetic sensor 13 are located inside the ends 14a and 14b of the conductor 14 in the X direction (third direction). That is, when viewed along the Z direction, the busbar 12 and the magnetic sensor 13 are located between the ends 14a and 14b of the conductor 14 in the X direction, indicated by the dashed lines in FIG. 3 , and the dashed line extending in the Z1 direction. This configuration improves the frequency characteristics of the coreless current sensor 10. The improvement in the frequency characteristics of the current sensor 10 due to the provision of the conductor 14 will be described below with reference to FIGS. 4 and 5 .

[0025] Figure 4 is an explanatory diagram that shows the skin effect. In this figure, the circular parts represent the cross sections of the busbars, and the shades of color in the cross sections represent the current distribution. The darker the color in the cross section, the larger the current that flows.

[0026] As shown in the first figure from the left, when a direct current flows through the conductor, the current distribution is uniform between the surface and the center of the conductor. In contrast, when an alternating current flows through the conductor, as shown in the second to fourth figures from the left, the skin effect causes the current to concentrate on the surface of the conductor, and the further away from the surface of the conductor (the closer to the center of the conductor's cross section), the more difficult it is for the current to flow. This tendency for the current to concentrate on the surface of the conductor becomes stronger as the frequency of the alternating current increases, reducing the measurement accuracy of the current sensor 10.

[0027] 5 is an explanatory diagram schematically illustrating the mechanism by which the flat conductor 14 acts on the busbar 12. For ease of explanation of the mechanism, the busbar 12 is shown in the figure as a cylinder with a circular cross section. The arrows in the figure also schematically illustrate the current flowing inside the busbar 12, with the longer the arrow, the greater the current flowing.

[0028] As shown in (a1) of the upper part of the figure (FIGS. 5(a1) to (a4)), when an AC current I flows through the bus bar 12 as a current to be measured, a magnetic field H is generated inside and around the bus bar 12 (a2). This magnetic field H generates an eddy current I in the bus bar 12. E is generated, and an eddy current I E By this, the magnetic field H E is generated (a3). Eddy current I E The eddy current I flows in the opposite direction to the AC current I at the center of the bus bar 12, and flows in the same direction as the AC current I on the surface of the bus bar 12. E Therefore, the further away from the surface of the bus bar 12, i.e., the closer to the center, the more difficult it is for the current to flow. The magnetic sensor 13 (see FIGS. 2 and 3) detects the magnetic field H generated by the AC current I and the eddy current I E The magnetic field H generated by E The combined magnetic field H+H E This eddy current I E The magnetic field H caused by E is a measurement error of the current sensor 10, and increases as the frequency of the AC current increases (a4).

[0029] Therefore, as shown in the lower part of FIG. 5 (FIGS. 5(b1) to (b4)), a flat conductor 14 is disposed near the surface of the bus bar 12, thereby preventing the eddy current I E The magnetic field H caused by E That is, as shown in (b1) in the lower part, when an AC current I as a current to be measured flows through the busbar 12, a magnetic field H is generated inside and around the busbar 12 (b2). This magnetic field H generates an eddy current I in the conductor 14 arranged near the surface of the busbar 12. E ' occurs, and this eddy current I E ' by the magnetic field H E An eddy current I ′ is generated in the conductor 14 (b3). E The magnetic field H generated by E ' is the eddy current I generated in the bus bar 12 E The magnetic field H caused by E Therefore, the magnetic field H generated in the conductor 14 E ', the eddy current I E The magnetic field H caused by E That is, the magnetic field detected by the magnetic sensor 13 can cancel out all or part of the magnetic field H+H E +H E '≒H, and the magnetic field H caused by the eddy current in the bus bar 12 E The influence of the above can be reduced (b4).

[0030] That is, by arranging the flat (plate) shaped conductor 14 opposite to the bus bar 12, the eddy current I generated in the bus bar 12 is E and the opposite eddy current I E ' is generated in the conductor 14, and the eddy current I E This can cancel the influence of the magnetic field H on the current sensor 10. Therefore, the occurrence of a phase delay when the frequency of the current to be measured flowing through the bus bar 12 is high is suppressed, and the measurement accuracy of the current sensor 10 is improved.

[0031] FIG. 6 is a graph showing the results of a simulation of the phase characteristics of a conventional current sensor and the current sensor 10 of this embodiment, which includes the conductor 14 made of aluminum (Al). The conventional current sensor differs from the current sensor 10 of this embodiment only in that it does not include the conductor 14; other configurations are identical. The simulation was performed with a distance D (see FIG. 3 ) between the busbar 12 and the conductor 14 of 14 mm and a frequency of 1 kHz for the AC current to be measured flowing through the busbar 12. The simulation results in FIG. 6 show that the current sensor 10 has superior phase characteristics to the conventional current sensor, and that the inclusion of the conductor 14 significantly improves the phase characteristics of the current sensor. Note that the distance D refers to the distance between the center points of the busbar 12 and the conductor 14 in the Z direction.

[0032] 7 is a cross-sectional view schematically illustrating the configuration of a current sensor 20 according to this embodiment. As shown in the figure, the current sensor 20 differs from the current sensor 10 of the first embodiment in that it includes magnetic shielding plates 25A and 25B. By including the magnetic shielding plates 25A and 25B in the current sensor 20, magnetic noise can be suppressed, thereby reducing output errors.

[0033] Both the magnetic shield plate 25A (first magnetic shield plate) and the magnetic shield plate 25B (second magnetic shield plate) included in the current sensor 20 are flat magnetic shields having a plane parallel to the XY plane. The magnetic shield plate 25B, the bus bar 12, the magnetic sensor 13, the substrate 15, the magnetic shield plate 25A, and the conductor 14 are arranged in this order from the Z1 side to the Z2 side in the Z direction.

[0034] The configuration in which the magnetic shield plate 25A is disposed between the magnetic sensor 13 and the conductor 14 reduces the distance between the magnetic shield plate 25A and the magnetic sensor 13. This increases the effect of shielding magnetic noise by the magnetic shield plate 25A.

[0035] The configuration in which the magnetic sensor 13 and the bus bar 12 are disposed between the magnetic shield plates 25A and 25B can suppress magnetic noise from the Z1 direction and the Z2 direction toward the magnetic sensor 13, thereby effectively shielding the magnetic noise. However, the present invention can also be implemented with a configuration including only one of the magnetic shield plates 25A and 25B.

[0036] The magnetic shield plates 25A and 25B are preferably made of a material having a lower electrical resistance than the conductor 14.

[0037] 8 is a cross-sectional view schematically illustrating a modified current sensor 21. Current sensor 21 differs from current sensor 20 in that, instead of the pair of magnetic shield plates 25A and 25B, current sensor 21 includes a magnetic shield 26 that is U-shaped when viewed along the Y direction (second direction).

[0038] The magnetic shield 26 has side wall portions 26a, 26a arranged at a distance on both sides of the magnetic sensor 13 and the bus bar 12 in the X direction (third direction), and a bottom portion 26b arranged on the opposite side of the magnetic sensor 13 across the bus bar 12.

[0039] The bottom portion 26b is formed in a flat plate shape having a plate surface parallel to the XY plane, and is disposed on the Z1 side in the Z direction relative to the bus bar 12, facing the bus bar 12. The side wall portions 26a, 26a are made of flat plates having plate surfaces parallel to the YZ plane, and extend from both ends of the bottom portion 26b in the X direction toward the Z2 side in the Z direction.

[0040] 8 , the magnetic sensor 13 is disposed between the side walls 26 a of the magnetic shield 26. That is, when viewed along the X direction, the magnetic sensor 13 is disposed at a position where the magnetic sensor 13 overlaps the side walls 26 a. By disposing the magnetic sensor 13 between the side walls 26 a in this manner, the magnetic shield 26 can effectively suppress the disturbance magnetic field acting on the magnetic sensor 13.

[0041] 9 is a graph showing the results of a simulation of the phase characteristics of a conventional current sensor and the current sensor 20 of the present embodiment shown in FIG. The conventional current sensor and the current sensor 20 are identical in configuration except that the conventional current sensor does not include the conductor 14. A simulation was performed with the AC current to be measured flowing through the bus bar 12 at a frequency of 1 kHz and the distance D (see FIG. 3 ) between the bus bar 12 and the conductor 14 set to 14 mm. The simulation results showed that the current sensor 20 had superior phase characteristics to the conventional current sensor. This indicates that the phase characteristics of the current sensor 20, including the magnetic shield plates 25A and 25B, can be improved by providing the conductor 14.

[0042] Fig. 10 is a graph of a simulation result showing the relationship between the distance D between the bus bar 12 and the conductor 14 and the phase characteristics in the current sensor 20. The graph in Fig. 10 shows the results of evaluating the phase characteristics of the current sensor 20 by simulation, with the frequency of the AC current in the bus bar 12 set to 1 kHz and the distance D between the bus bar 12 and the conductor 14 being changed.

[0043] 10 reveals that, at least when the distance D between the busbar 12 and the conductor 14 is in the range of 8 mm to 14 mm, the phase characteristics are slightly better as the distance D becomes smaller, but there is no significant difference depending on the distance D. In the current sensor 20, the distance D in the Z direction between the busbar 12 and the cover portion 17 is usually 16 mm or less. Therefore, the conductor 14 provided on the surface of the cover portion 17 on the Z2 side opposite the busbar 12 (see FIGS. 7 and 1) can improve the phase characteristics of the current sensor 20.

[0044] Third Embodiment In this embodiment, in a configuration including a pair of magnetic sensors 13A and 13B, current sensors 30, 31, and 32 that differ from the current sensors 10 and 20 will be described below.

[0045] 11 is a plan view schematically illustrating the configuration of the current sensor 30 according to this embodiment. As shown in the figure, the current sensor 30 includes a pair of magnetic sensors 13A and 13B, each of which has a detection direction opposite to each other. Therefore, the magnetic field emitted by the bus bar 12 can be detected as the difference between the magnetic fields detected by the pair of magnetic sensors 13A and 13B. By using the difference between the magnetic fields detected by the pair of magnetic sensors 13A and 13B, the influence of magnetic noise can be reduced, thereby improving the measurement accuracy of the current sensor 30.

[0046] For example, geomagnetism has an equal effect on the pair of magnetic sensors 13A and 13B. Therefore, by using the differential output, which is the difference between the magnetic fields detected by the pair of magnetic sensors 13A and 13B, the effect of geomagnetism can be removed from the outputs of the magnetic sensors 13A and 13B. Furthermore, many magnetic noises other than geomagnetism also have an effect on the magnetic sensors 13A and 13B in the same direction and to the same extent. Therefore, by using the differential output, the effect of magnetic noise can be suppressed, thereby improving the measurement accuracy of the current sensor 30.

[0047] 11, the detection directions indicated by the arrows are the X1 direction for magnetic sensor 13A and the X2 direction for magnetic sensor 13B, but magnetic sensor 13A may be in the X2 direction and magnetic sensor 13B in the X1 direction. Also, while the current sensor 30 is shown as having two detection locations, with magnetic sensors 13A and 13B provided at each detection location, the number of detection locations may be three or more.

[0048] 12 is a plan view schematically illustrating the configuration of a current sensor 31 according to a modified example. As shown in the figure, the current sensor 31 includes two bus bars 12, and when viewed along the Z direction, magnetic sensors 13A and 13B are positioned between the two bus bars 12. With this configuration, the currents to be measured flowing through the two bus bars 12 can be accurately detected by the operational outputs of the magnetic sensors 13A and 13B, respectively.

[0049] 13 is a plan view schematically illustrating the configuration of a current sensor 32 according to another modification. As shown in the figure, the current sensor 32 includes a U-shaped bus bar 33 when viewed along the Z direction, and magnetic sensors 13A and 13B are located between two parallel portions of the bus bar 33. With this configuration, the current to be measured flowing through the bus bar 33 can be accurately detected by the operational outputs of the magnetic sensors 13A and 13B.

[0050] The embodiments disclosed in this specification are illustrative in all respects and are not limited to these embodiments. The scope of the present invention is defined by the claims rather than by the description of the above-described embodiments alone, and is intended to include all modifications within the meaning and scope of the claims.

[0051] The present invention is useful as a current sensor for measuring a current to be measured flowing through equipment, for example, in order to control the power supply system of a vehicle or the like equipped with various equipment.

[0052] 10: Current sensor 12: Bus bar 13: Magnetic sensor 13A: Magnetic sensor 13B: Magnetic sensor 14: Conductor 14a: End 14b: End 15: Board 16: Housing 17: Cover 20: Current sensor 21: Current sensor 25A: Magnetic shield plate 25B: Magnetic shield plate 26: Magnetic shield 26a: Side wall 26b: Bottom 30: Current sensor 31: Current sensor 32: Current sensor 33: Bus bar D: Distance H: Magnetic field H E : Magnetic field H E ': magnetic field I: AC current I E : Eddy current I E ': Eddy current

Claims

1. A current sensor comprising: a bus bar through which a current to be measured flows; and a magnetic sensor arranged so as to be able to detect a magnetic field generated by the bus bar, the current sensor having a conductor made of a non-magnetic material, the conductor being arranged on the opposite side of the bus bar with the magnetic sensor in between.

2. A current sensor as described in claim 1, wherein the direction in which the bus bar, the magnetic sensor and the conductor are arranged is defined as a first direction, the direction in which the bus bar extends perpendicular to the first direction is defined as a second direction, and a direction perpendicular to the first direction and the second direction is defined as a third direction, and the conductor is formed in a flat plate shape parallel to a plane formed by the second direction and the third direction.

3. The current sensor according to claim 2, wherein, when viewed along the first direction, the bus bar and the magnetic sensor are positioned inside each end of the conductor in the third direction.

4. The current sensor according to claim 1, wherein said non-magnetic material is aluminum.

5. The current sensor of claim 1, further comprising a magnetic shield.

6. The current sensor according to claim 5, wherein the magnetic shield has a flat first magnetic shield plate, and the first magnetic shield plate is disposed between the magnetic sensor and the conductor.

7. A current sensor as described in claim 5, wherein the magnetic shield has a flat first magnetic shield plate and a flat second magnetic shield plate, and the magnetic sensor and the bus bar are arranged between the first magnetic shield plate and the second magnetic shield plate.

8. A current sensor as described in claim 5, wherein the direction in which the bus bar, the magnetic sensor and the conductor are arranged is defined as a first direction, the direction in which the bus bar is extended is defined as a second direction, and a direction perpendicular to the first direction and the second direction is defined as a third direction, the magnetic shield has a U-shape when viewed along the second direction, and has side wall portions spaced apart on both sides of the magnetic sensor and the bus bar in the third direction, and a bottom portion positioned on the opposite side of the magnetic sensor in the first direction, sandwiching the bus bar.

9. The current sensor according to claim 1, comprising a pair of said magnetic sensors each having an opposite detection direction, and detecting the magnetic field emitted by said bus bar as a difference between magnetic fields detected by said pair of said magnetic sensors.

Images