Current detection device

Abstract

A current detection device comprises a flat plate–shaped conduction member (50) through which current flows in an extension direction, a magnetism detector (23, 24) that converts a measured magnetic field to a magnetism detection signal, and a shield (30, 40) that suppresses input of electromagnetic noise to the magnetism detector. The shield includes a plate-shaped first shield (30) and a plate-shaped second shield (40) that are opposite each other with a gap therebetween and include portions that extend in both the extension direction and the width direction. A portion of the conduction member is between the first shield and the second shield. The magnetism detector is between the first shield and the second shield. The magnetism detector detects magnetic fields that pass therethrough. The first shield has a first opposing surface (32). The second shield has a second opposing surface (42). A recess (321) is formed in at least one of the first opposing surface and the second opposing surface. The recess is formed at a position that does not coincide with the magnetism detector in the direction of opposition.

Description

Current Detection Device Cross - reference to Related Applications

[0001] This application is based on Japanese Patent Application No. 2024 - 225380 filed on December 20, 2024, the contents of which are incorporated herein by reference.

[0002] This disclosure relates to a current detection device.

[0003] Conventionally, a current detection device having a conductive member through which current flows, a magnetoelectric conversion unit that converts a magnetic field generated by the flow of current through the conductive member into an electrical signal, and a first shield and a second shield that suppress the input of electromagnetic noise into the magnetoelectric conversion unit is known (see, for example, Patent Document 1). In this current detection device, a part of the conductive member and the magnetoelectric conversion unit are disposed between a first shield and a second shield that are spaced apart and opposed to each other.

[0004] The first shield extends in the extension direction in which the conductive member extends and has a plate - like shape that extends in a lateral direction orthogonal to the extension direction. Also, the first shield has a shape in which the lateral length of the central portion in the extension direction is longer compared to the lateral lengths of both end portions in the extension direction. And the four corners of the plate - like first shield are formed with cutouts.

[0005] With these configurations, even if electromagnetic noise is input to the first shield in the current detection device described in Patent Document 1, it is difficult for the electromagnetic noise to permeate from one side of the both end portions to the other side through the central portion side of the first shield. For this reason, it is difficult for the central portion of the first shield to be magnetically saturated due to the electromagnetic noise input to the first shield, and leakage of electromagnetic noise from the central portion is suppressed. Therefore, it is possible to suppress deterioration in the detection accuracy of the current value detected by the current detection device due to electromagnetic noise being input to the magnetoelectric conversion unit.

[0006] Specification of Japanese Patent No. 7172079

[0007] By the way, in the current detection device described in Patent Document 1, the first shield and the second shield are arranged so as to sandwich the conductive member and the electromagnetic conversion unit. Therefore, when a current flows through the conductive member and a magnetic field is generated around the conductive member, the first shield and the second shield form a magnetic circuit in which magnetic flux flows around the conductive member. However, if magnetic flux leaks from the magnetic circuit formed by the shield members and this leaked magnetic flux is input to the magnetoelectric conversion unit as electromagnetic noise, it can cause a deterioration in the detection accuracy of the current value detected by the current detection device.

[0008] In a configuration where the central portion of the shielding member is longer than the ends, as described in Patent Document 1, the magnetic flux input to the shielding member is less likely to pass through the central portion from one end to the other. Therefore, even if magnetic flux flows through the magnetic circuit composed of the shielding member due to current flowing through the conductive member, the central portion of the shielding member is less likely to become magnetically saturated, and leakage of electromagnetic noise from the shielding member is suppressed.

[0009] However, the larger the current value flowing through the conductive member, the greater the magnetic flux input to the magnetic circuit composed of the shielding member. Through diligent research by the inventors, it was found that when the current value flowing through the conductive member increases, the configuration described in Patent Document 1 may not be able to sufficiently suppress the input of magnetic flux from one end of the shielding member to the other.

[0010] If the input of magnetic flux from one end to the other of such a shielding member cannot be sufficiently suppressed, the central part of the shielding member may become magnetically saturated, potentially causing magnetic flux to leak from the magnetic circuit formed by the shielding member. When the magnetic flux leaking from the magnetic circuit formed by the shielding member is input to the magnetoelectric conversion unit as electromagnetic noise, it can cause a deterioration in the detection accuracy of the current value detected by the current detection device.

[0011] In view of the above points, this disclosure aims to provide a current detection device capable of improving detection accuracy.

[0012] According to one aspect of this disclosure, the current detection device comprises a conductive member having a flat plate shape through which current flows in an extension direction with one direction as the extension direction, a magnetic detection unit that converts the magnetic field to be measured generated by the flow of current through the conductive member into a magnetic detection signal, and a shielding unit that suppresses the input of electromagnetic noise to the magnetic detection unit, wherein the shielding unit has a plate-shaped first shield and a second shield that are spaced apart from each other and face each other in predetermined opposing directions, and include portions that extend in the extension direction and in the width direction intersecting the extension direction, respectively, a portion of the conductive member is disposed between the first shield and the second shield, the magnetic detection unit is disposed between the first shield and the second shield and has a magnetic detection element that detects a magnetic field passing through it, the first shield has a first opposing surface that faces the second shield, the second shield has a second opposing surface that faces the first shield, and at least one of the opposing surfaces of the first and second opposing surfaces has a recess formed in the opposing direction, the recess is formed at a position that does not overlap with the magnetic detection element in the opposing direction.

[0013] According to this, magnetic flux is less likely to penetrate the portion forming the opposing surface of the shield on the side where the recess is formed, thus reducing the likelihood of magnetic saturation on the opposing surface caused by the concentration of magnetic flux on that surface. As a result, the magnetic flux flowing through the magnetic circuit formed by the first and second shields is less likely to be hindered from being input to these first and second shields by magnetic saturation, and electromagnetic noise input to the magnetic detection unit can be suppressed. Therefore, even if a relatively large current flows through the conductive member, the deterioration of the detection accuracy of the current detection device caused by leakage of magnetic flux from the magnetic circuit formed by the first and second shields can be suppressed, and the detection accuracy of the current detection device can be improved.

[0014] Furthermore, by forming the recess in a position that does not overlap with the magnetic detection unit in the opposing direction, even if the shield thickness is reduced and the shielding performance deteriorates due to the formation of the recess, the input of external noise to the magnetic detection unit can be suppressed.

[0015] This is a schematic diagram of a battery management system to which the current detection device according to the first embodiment is applied. This is a perspective view of the current detection device according to the first embodiment. This is an exploded perspective view of the current detection device according to the first embodiment. This is a view of the sensor housing according to the first embodiment from one side in the third direction. This is a view of the sensor housing according to the first embodiment from the other side in the third direction. This is a view of the wiring board according to the first embodiment from one side in the third direction. This is a view of the wiring board according to the first embodiment from the other side in the third direction. This is a block diagram of the first sensing unit and the second sensing unit according to the first embodiment. This is a view of the conductive busbar and wiring board according to the first embodiment from one side in the first direction. This is a view of the conductive busbar according to the first embodiment from one side in the third direction. This is a view of the conductive busbar, the first shield and the second shield according to the first embodiment from one side in the second direction. This is a view of the first shield according to the first embodiment from one side in the third direction. This is a view of the first shield according to the first embodiment from the other side in the third direction. This is a view of the second shield according to the first embodiment from one side in the third direction. This is a view of the second shield according to the first embodiment from the other side in the third direction. This is an exploded perspective view of the second shield according to the first embodiment. This is an exploded perspective view of the first shield according to the first embodiment. This is an explanatory diagram for explaining the recess on the back side formed on the first shield according to the first embodiment. This is an explanatory diagram for explaining the operation of the current detection device according to the first embodiment. This is an explanatory diagram for explaining the flow of magnetic flux flowing on the first back surface of the first shield. This is an explanatory diagram for explaining the flow of magnetic flux input to the first shield and the second shield. This is an explanatory diagram for explaining the flow of magnetic flux input to the first and second comparison shields. This is a contour diagram showing the magnetic flux density of the first and second comparison shields when a relatively large current flows through the comparison current detection device. This is a contour diagram showing the magnetic flux density of the first comparison back surface when a relatively large current flows through the comparison current detection device. This is an explanatory diagram for explaining the output value of the magnetic detection signal that changes due to magnetic flux saturation of the first and second back surfaces. This is a contour diagram showing the magnetic flux density of the first and second comparison shields when a large current flows through the comparison current detection device.This is a contour diagram showing the magnetic flux density of the first and second comparison shields when a relatively large current flows through the comparison current detection device. This is an explanatory diagram for explaining the detection error of the current value detected by the comparison current detection device and the current detection device. This is a contour diagram showing the magnetic flux density of the first and second shields when a relatively large current flows through the current detection device according to the first embodiment. This is a contour diagram showing the magnetic flux density of the first and second shields when a relatively large current flows through the current detection device according to the first embodiment. This is a view of the conductive busbar, first shield, and second shield according to the first modified example of the first embodiment, seen from one side in the second direction. This is a contour diagram showing the magnetic flux density of the first and second shields when a relatively large current flows through the current detection device according to the first modified example of the first embodiment. This is an explanatory diagram for explaining the recess on the back side formed on the first shield according to the second modified example of the first embodiment. This is an explanatory diagram for explaining the recess on the back side formed on the first shield according to the second modified example of the first embodiment. This is an explanatory diagram illustrating a recess on the back side formed on the first shield according to a third modification of the first embodiment. This is a view of the conductive busbar, first shield, and second shield according to a fourth modification of the first embodiment, seen from one side in the second direction. This is an enlarged view of portion XXXVII in Figure 36. This is a view of the conductive busbar, first shield, and second shield according to the second embodiment, seen from one side in the second direction. This is an enlarged view of portion XXXIX in Figure 38. This is a contour diagram showing the magnetic flux density of the first and second shields when a relatively large current flows through the current detection device according to the second embodiment. This is a view of the conductive busbar, first shield, and second shield according to a first modification of the second embodiment, seen from one side in the second direction. This is a contour diagram showing the magnetic flux density of the first and second shields when a relatively large current flows through the current detection device according to the first modification of the second embodiment. This is a view of the conductive busbar, first shield, and second shield according to a second modification of the second embodiment, seen from one side in the second direction. This is a view of the conductive busbar, first shield, and second shield according to the third embodiment, seen from one side in the second direction. This is an enlarged view of the XLV portion of Figure 44.This is a contour diagram showing the magnetic flux density of the first and second shields when a relatively large current flows through the current detection device according to the third embodiment. This is a view of the conductive busbar, first shield, and second shield according to the first modification of the third embodiment, seen from one side in the second direction. This is an enlarged view of the XLVIII portion of Figure 47. This is a contour diagram showing the magnetic flux density of the first and second shields when a relatively large current flows through the current detection device according to the first modification of the third embodiment. This is a view of the conductive busbar, first shield, and second shield according to the second modification of the third embodiment, seen from one side in the second direction. This is an enlarged view of the LI portion of Figure 50. This is a view of the conductive busbar, first shield, and second shield according to the second modification of the third embodiment, seen from one side in the second direction. This is an enlarged view of the LIII portion of Figure 52. This is a view of the conductive busbar, first shield, and second shield according to the fourth embodiment, seen from one side in the second direction. This is an enlarged view of the LV portion of Figure 54. This is a contour diagram showing the magnetic flux density of the first and second comparative shields when a relatively large current flows through the comparative current detection device. This is a contour diagram showing the magnetic flux density of the first and second shields when a relatively large current flows through the current detection device according to the fourth embodiment. This is a view of the conductive busbar, first shield, and second shield according to the third modification of the fourth embodiment, seen from one side in the second direction. This is a view of the conductive busbar, first shield, and second shield according to the third modification of the fourth embodiment, seen from one side in the second direction.

[0016] Embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the prior embodiments will be denoted by the same reference numerals, and their descriptions may be omitted. Also, if only a part of a component is described in an embodiment, the components described in the prior embodiments can be applied to the other parts of that component. The following embodiments can be partially combined with each other, even if not explicitly stated, as long as it does not impede the combination.

[0017] (First Embodiment) This embodiment will be described with reference to Figures 1 to 30. The current detection device 1 of this embodiment is used, for example, in a battery management system VMS shown in Figure 1, which manages the battery VT of a vehicle. The battery management system VMS is a circuit system having conductive paths through which current flows, and is a temperature management system that manages the temperature of the battery VT, which is the object to be managed, in order to use the battery VT safely and efficiently. Current flows through the conductive paths of the battery management system VMS as the battery VT discharges. The current detection device 1 detects the current flowing through the conductive paths. First, the battery management system VMS will be described with reference to Figure 1. As shown in Figure 1, the battery management system VMS includes a battery VT, a battery ECU 200, and a current detection device 1.

[0018] The battery VT can be a secondary battery such as a lithium-ion secondary battery or a nickel-metal hydride secondary battery. As shown in Figure 1, the battery VT is connected to an inverter INV mounted on the vehicle and supplies power to the inverter INV to drive the vehicle. The inverter INV is connected to a motor generator (not shown) and outputs an alternating current for the motor generator to rotate, and also converts the power generated by the motor generator into a direct current to charge the battery VT.

[0019] The battery ECU 200 monitors the State of Charge (SOC) of the battery VT based on the current detected by the current detection device 1 (described later) and controls the charging of the battery VT. As shown in Figure 1, the battery ECU 200 is connected to the EV-ECU 300. The battery ECU 200 and EV-ECU 300 are computers mainly consisting of a control circuit equipped with a CPU (not shown), recording media such as ROM and RAM, input / output interfaces, and buses connecting them. ECU stands for electronic control unit. SOC stands for state of charge. CPU, ROM, and RAM are abbreviations for Central Processing Unit, Read Only Memory, and Random Access Memory, respectively. The ROM and RAM of the battery ECU 200 and EV-ECU 300 are composed of non-transitional physical storage media.

[0020] The EV-ECU 300 controls the amount of power supplied to the motor generator (not shown) and the amount of regenerative power from the drive motor based on control signals obtained from the battery ECU 200. The EV-ECU 300 is connected to the battery ECU 200.

[0021] The current detection device 1 is connected between the battery VT and the inverter INV. Specifically, the current detection device 1 is electrically connected to the inverter INV via the energized busbar BU. The current detection device 1 detects and calculates the current flowing from the battery VT to the inverter INV, and also detects and calculates the current flowing from the inverter INV to the battery VT.

[0022] Next, the current detection device 1 will be described. As shown in Figures 2 and 3, the current detection device 1 includes a sensor housing 10, a wiring board 20, a first shield 30, a second shield 40, and a conductive busbar 50. In the current detection device 1, one side of the conductive busbar 50 is connected to the battery VT, and the other side is connected to the inverter INV via a current-carrying busbar BU. Therefore, the DC current flowing from the battery VT to the inverter INV flows through the conductive busbar 50 in the current detection device 1. The current detection device 1 detects the DC current flowing through the conductive busbar 50. The conductive busbar 50 corresponds to a conductive material.

[0023] First, the components of the current detection device 1 will be described in detail individually. In the following, the three directions that are orthogonal to each other will be referred to as the first direction D1, the second direction D2, and the third direction D3. The second direction D2 corresponds to the extension direction of the conductive busbar 50. The first direction D1 is the direction that intersects the second direction D2, specifically the direction perpendicular to the second direction D2, and corresponds to the width direction of the conductive busbar 50. The third direction D3 is the direction that intersects the first direction D1 and the second direction D2, specifically the direction perpendicular to the first direction D1 and the second direction D2, and corresponds to the thickness direction of the conductive busbar 50.

[0024] <Sensor Housing> The sensor housing 10 is made of an insulating resin material. As shown in Figures 2 and 3, the sensor housing 10 is provided with a wiring board 20, a first shield 30, and a second shield 40. A portion of the conductive busbar 50 is also insert-molded into the sensor housing 10. Specifically, the wiring board 20 is fixed to the sensor housing 10 in a manner that faces the portion of the conductive busbar 50 that is insert-molded into the sensor housing 10. The first shield 30 and the second shield 40 are fixed to the sensor housing 10 in a manner that they are spaced apart from each other. The portions of the wiring board 20 and the conductive busbar 50 that face each other are positioned between the first shield 30 and the second shield 40.

[0025] The conductive busbar 50, the wiring board 20, the first shield 30, and the second shield 40 are arranged spaced apart in the third direction D3. Furthermore, connection terminals 14 that are electrically and mechanically connected to the wiring board 20 are insert-molded into the sensor housing 10. These connection terminals 14 are electrically connected to the battery ECU 200 via a wire harness or the like.

[0026] As shown in Figures 2 to 5, the sensor housing 10 has a base portion 11, an insulating portion 12, and a connector portion 13. The base portion 11 is a rectangular parallelepiped with the first direction D1 as its extension direction. On one side of the base portion 11 in the third direction D3, there are multiple substrate support pins 111 for supporting the wiring board 20 and multiple first shield support pins 112 for supporting the first shield 30. On the other side of the base portion 11 in the third direction D3, there are multiple second shield support pins 113 for supporting the second shield 40.

[0027] The substrate support pins 111, the first shield support pins 112, and the second shield support pins 113 are formed to extend in the third direction D3. The wiring board 20 is housed in the sensor housing 10 such that the busbar-facing surfaces 22, described later, contact the tips of the substrate support pins 111. The wiring board 20 and the substrate support pins 111 are bonded together, for example, with an adhesive. The first shield 30 is mounted in the sensor housing 10 such that the first back surface 32, described later, contacts the tips of the first shield support pins 112.

[0028] The first shield 30 and the first shield support pin 112 are bonded together, for example, by an adhesive. The second shield 40 is mounted on the sensor housing 10 such that the second back surface 42, described later, contacts the tip of the second shield support pin 113. The second shield 40 and the second shield support pin 113 are bonded together, for example, by an adhesive. As a result, the base 11 is provided with the first shield 30 on one side in the third direction D3 and the second shield 40 on the other side in the third direction D3.

[0029] As shown in Figure 4, the insulating portions 12 are formed on one and the other side of the base portion 11 in the second direction D2. These two insulating portions 12 extend in the second direction D2 away from the base portion 11. The two insulating portions 12 are aligned in the second direction D2 through the base portion 11. The conductive busbar 50 is partially covered by the base portion 11 and each of the two insulating portions 12.

[0030] As shown in Figures 2 and 3, the connector portion 13 is formed on the other side of the base portion 11 in the third direction D3. The connector portion 13 is cylindrical and extends in the third direction D3 away from the base portion 11. Part of the connection terminal 14 is housed inside the connector portion 13. The connector portion 13 is connected to a connector such as a wire harness.

[0031] The connection terminal 14 extends in the third direction D3. One side of the connection terminal 14 in the third direction D3 is exposed from the base 11 and surrounded by the base 11, while the other side is surrounded by the connector portion 13. In the first direction D1, the connection terminal 14 is separated from the portion of the conductive busbar 50 covered by the base 11.

[0032] As described above, a DC current flows through the conductive busbar 50 to input and output the battery VT. A less current than the DC current flowing through the conductive busbar 50 flows through the connection terminal 14 between the wiring board 20 and the battery ECU 200. If the creepage distance between the conductive busbar 50 and the connection terminal 14 is small, there is a risk that the conductive busbar 50 and the connection terminal 14 will conduct electricity and short circuit.

[0033] To prevent such malfunctions, ribs 121 are formed on each of the insulating portions 12 provided on one side and the other side of the base portion 11 in the second direction D2. The ribs 121 protrude from one side of the insulating portion 12 in the third direction D3. The ribs 121 extend in the first direction D1. The length of the ribs 121 in the first direction D1 is longer than the length of the conductive busbar 50 in the first direction D1.

[0034] The ribs 121 provided on one side of the base 11 in the second direction D2 and the ribs 121 provided on the other side of the base 11 in the second direction D2 are located between the portion of the conductive busbar 50 exposed from the sensor housing 10 and the portion of the connection terminal 14 exposed from the base 11. These ribs 121 increase the creepage distance between the conductive busbar 50 and the connection terminal 14 on the surface of the sensor housing 10. This suppresses short circuits between the conductive busbar 50 and the connection terminal 14.

[0035] Furthermore, the ribs 121 provided on one side of the base 11 in the second direction D2 and the ribs 121 provided on the other side of the base 11 in the second direction D2 are located between the portion of the conductive busbar 50 exposed from the sensor housing 10 and the first shield 30 and the second shield 40. This also suppresses short circuits between the conductive busbar 50 and the first shield 30 and the second shield 40. By extending the creepage distance with the ribs 121, the length of the insulating portion 12 in the second direction D2 can be shortened. This suppresses an increase in the size of the current detection device 1.

[0036] <Wiring board> As shown in Figures 6 and 7, the wiring board 20 is formed in a flat plate shape. Specifically, the wiring board 20 is formed in a flattened shape with a thin thickness in the third direction D3. The wiring board 20 is formed by laminating multiple insulating resin layers and conductive metal layers in the third direction D3. The wiring board 20 has a shield-facing surface 21 on one side in the third direction D3 that faces the first shield 30, and a busbar-facing surface 22 on the other side in the third direction D3 that faces the conductive busbar 50.

[0037] As shown in Figure 6, a first sensing unit 23, a second sensing unit 24, and a third sensing unit 25 are mounted on the shield-facing surface 21 of the wiring board 20. The first sensing unit 23, the second sensing unit 24, and the third sensing unit 25 mounted on the wiring board 20 are housed in the sensor housing 10. As shown in Figure 7, a first thermistor 71 and a second thermistor 72 are mounted on the busbar-facing surface 22 of the wiring board 20. The first magnetoelectric conversion unit 231a of the first sensing unit 23 (described later), the second magnetoelectric conversion unit 241a of the second sensing unit 24 (described later), and the third sensing unit 25 are each mounted in a location facing the conductive busbar 50.

[0038] The first sensing unit 23 and the second sensing unit 24 are magnetic detection units that generate a detection signal corresponding to the magnetic flux generated in the magnetic field when current flows through the conductive busbar 50. As shown in Figure 8, the first sensing unit 23 has a first ASIC 231 and a first filter 232. The second sensing unit 24 has a second ASIC 241 and a second filter 242.

[0039] The first ASIC 231 and the first filter 232 are electrically connected to each other via the wiring pattern on the wiring board 20. The second ASIC 241 and the second filter 242 are electrically connected to each other via the wiring pattern on the wiring board 20. The wiring pattern connecting the first ASIC 231 and the first filter 232 is electrically connected to the connection terminal 14. The wiring pattern connecting the second ASIC 241 and the second filter 242 is electrically connected to the connection terminal 14. ASIC stands for application specific integrated circuit.

[0040] The first sensing unit 23, the second sensing unit 24, and the third sensing unit 25 may be mounted on the busbar-facing surface 22. Also, the first thermistor 71 and the second thermistor 72 may be mounted on either or both of the shield-facing surfaces 21.

[0041] Incidentally, the first sensing unit 23 and the second sensing unit 24 are formed with the same configuration as each other. For this reason, only the first sensing unit 23 will be described in detail below, and the detailed explanation of the second sensing unit 24 will be omitted.

[0042] <ASIC> The first ASIC 231 has a first magnetoelectric conversion unit 231a and a first processing circuit 231b. The first magnetoelectric conversion unit 231a and the first processing circuit 231b are electrically connected. The first magnetoelectric conversion unit 231a has a plurality of magnetic detection elements that detect magnetic fields passing through it. The magnetic detection elements can be magnetoresistive elements whose resistance value changes according to the transmitted magnetic field. The resistance value of these magnetoresistive elements changes according to the transmitted magnetic field along the shield-facing surface 21. That is, the resistance value of the magnetoresistive element changes according to the component along the first direction D1 and the component along the second direction D2 of the transmitted magnetic field. In contrast, the resistance value of the magnetoresistive element does not change due to the transmitted magnetic field along the third direction D3. Therefore, even if external noise along the third direction D3 passes through the magnetoresistive element, its resistance value does not change as a result.

[0043] The magnetoresistive element has a pin layer with a fixed magnetization direction, a free layer whose magnetization direction changes according to the transmitted magnetic field, and a non-magnetic intermediate layer provided between the two. The magnetoresistive element may be a giant magnetoresistive element with a non-conductive intermediate layer, or a tunnel magnetoresistive element with a conductive intermediate layer. Alternatively, the magnetoresistive element may be an anisotropic magnetoresistive element. Furthermore, the first magnetoelectric conversion unit 231a may have a Hall element instead of a magnetoresistive element as a magnetic detection element.

[0044] The magnetoresistive effect element changes its resistance value according to the angle formed by the magnetization directions of the pin layer and the free layer. The magnetization direction of the pin layer is along the shield facing surface 21. The magnetization direction of the free layer is determined by the transmission magnetic field along the shield facing surface 21. The resistance value of the magnetoresistive effect element is minimized when the magnetization directions of the free layer and the fixed layer are parallel and in the same direction, and is maximized when the magnetization directions of the free layer and the fixed layer are parallel and in opposite directions to each other.

[0045] The first magnetoelectric conversion unit 231a includes a first one-sided element 231c and a first other-sided element 231d as the above-described magnetoresistive effect elements. The magnetization directions of the pin layers of the first one-sided element 231c and the first other-sided element 231d are different by 90°. Therefore, when the resistance values of the first one-sided element 231c and the first other-sided element 231d change respectively, the increase and decrease of the change are opposite. That is, when the resistance value of one of the first one-sided element 231c and the first other-sided element 231d decreases, the resistance value of the other increases by the same amount as the decrease amount of the resistance value of one.

[0046] The first magnetoelectric conversion unit 231a has two of the first one-sided element 231c and two of the first other-sided element 231d respectively. Then, the first one-sided element 231c and the first other-sided element 231d are connected in series in this order from the power supply potential toward the reference potential to form one half-bridge circuit. Further, the first other-sided element 231d and the first one-sided element 231c are connected in series in this order from the power supply potential toward the reference potential to form another half-bridge circuit. In these two half-bridge circuits like this, the order of the first one-sided element 231c and the first other-sided element 231d is reversed. For this reason, the midpoint potential of the two half-bridge circuits is configured such that when one potential drops, the other potential rises. In the first magnetoelectric conversion unit 231a, a full-bridge circuit is formed by combining these two half-bridge circuits.

[0047] The first magnetoelectric conversion unit 231a includes, in addition to the first one-sided element 231c and the first other-sided element 231d that constitute the above-described full-bridge circuit, a first differential amplifier 231e, a first feedback coil 231f, and a first shunt resistor 231h. The first differential amplifier 231e has the midpoint potentials of two half-bridge circuits input to its inverting input terminal and non-inverting input terminal. Also, from the output terminal of the first differential amplifier 231e toward the reference potential, the first feedback coil 231f and the first shunt resistor 231h are connected in series in this order.

[0048] With the connection configuration shown above, the first differential amplifier 231e outputs a signal from its output terminal according to the change in the resistance values of the first one-sided element 231c and the first other-sided element 231d that constitute the full-bridge circuit. This change in the resistance value is caused by the magnetic field along the shield-facing surface 21 passing through the first one-sided element 231c and the first other-sided element 231d. A magnetic field generated by the current flowing through the conductive bus bar 50 passes through the first one-sided element 231c and the first other-sided element 231d. This magnetic field is the measured magnetic field to be measured. Therefore, a current corresponding to the measured magnetic field flows through the input terminals of the first differential amplifier 231e.

[0049] The input terminals and output terminals of the first differential amplifier 231e are connected via a feedback circuit not shown in the figure. For this reason, the first differential amplifier 231e is in a virtual short circuit. Therefore, the first differential amplifier 231e operates such that the inverting input terminal and the non-inverting input terminal have the same potential. That is, the first differential amplifier 231e operates such that the current flowing through the input terminals and the current flowing through the output terminals become zero. As a result, a current corresponding to the measured magnetic field, that is, a feedback current, flows from the output terminal of the first differential amplifier 231e.

[0050] A feedback current flows between the output terminal of the first differential amplifier 231e and the reference potential via the first feedback coil 231f and the first shunt resistor 231h. This flow of feedback current generates a canceling magnetic field in the first feedback coil 231f. This canceling magnetic field passes through the first magnetoelectric conversion unit 231a. As a result, the magnetic field under test that passes through the first magnetoelectric conversion unit 231a is canceled out. Thus, the first magnetoelectric conversion unit 231a operates in such a way that the magnetic field under test that passes through it and the canceling magnetic field are in equilibrium. A feedback voltage corresponding to the amount of feedback current that generates the canceling magnetic field is generated at the midpoint between the first feedback coil 231f and the first shunt resistor 231h. This feedback voltage is output to the first processing circuit 231b as an electrical signal that detects the current under test.

[0051] The first processing circuit 231b includes a first adjustment amplifier 231j and a first threshold power supply 231k. The first adjustment amplifier 231j has the midpoint between the first feedback coil 231f and the first shunt resistor 231h connected to its non-inverting input terminal. The first threshold power supply 231k is also connected to the inverting input terminal of the first adjustment amplifier 231j. As a result, the first adjustment amplifier 231j outputs a differentially amplified feedback voltage.

[0052] Incidentally, the resistance values ​​of the first one-sided element 231c and the first other-sided element 231d that constitute the full-bridge circuit are temperature-dependent. Therefore, the output of the first adjustment amplifier 231j fluctuates with temperature changes. Accordingly, the first processing circuit 231b has a non-volatile memory that stores the relationship between the temperature and resistance value of the magnetoresistive element. This non-volatile memory is electrically rewritable.

[0053] Furthermore, the first processing circuit 231b is connected to the first thermistor 71 and the second thermistor 72, which will be described later, for temperature detection. The first processing circuit 231b may adjust the gain and offset of the first adjustment amplifier 231j by rewriting the information stored in the non-volatile memory based on the temperature information detected by the first thermistor 71 and the second thermistor 72. This makes it possible to correct fluctuations in the output of the first adjustment amplifier 231j caused by temperature changes.

[0054] <Filter> The first filter 232 has a first resistor 232a and a first capacitor 232b. As shown in Figure 8, the wiring board 20 has a wiring pattern formed thereon: a first power supply wiring 232c, a first output wiring 232d, and a first ground wiring 232e. The first ASIC 231 is connected to the first power supply wiring 232c, the first output wiring 232d, and the first ground wiring 232e, respectively. The output terminal of the first regulating amplifier 231j of the first ASIC 231 is connected to the first output wiring 232d.

[0055] The first resistor 232a of the first filter 232 is provided on the first output wiring 232d. The first capacitor 232b connects the first output wiring 232d and the first ground wiring 232e. As a result, the first filter 232 of the first sensing unit 23 is configured as a low-pass filter by the first resistor 232a and the first capacitor 232b. The output of the first ASIC 231 is output to the battery ECU 200 via this low-pass filter. As a result, the first sensing unit 23 outputs a signal from which high-frequency noise has been removed to the battery ECU 200. As described above, the first sensing unit 23 outputs an electrical signal corresponding to the DC current flowing through the conductive busbar 50 as a magnetic detection signal to the battery ECU 200.

[0056] The first sensing unit 23 of this embodiment has the configuration described above. The first sensing unit 23 and the second sensing unit 24 of this embodiment have the same configuration. Specifically, the second sensing unit 24 has a second magnetoelectric conversion unit 241a corresponding to the first magnetoelectric conversion unit 231a, and a second processing circuit 241b corresponding to the first processing circuit 231b. The second magnetoelectric conversion unit 241a has a second one-side element 241c corresponding to the first one-side element 231c, a second other-side element 241d corresponding to the first other-side element 231d, and a second differential amplifier 241e corresponding to the first differential amplifier 231e. Furthermore, the second magnetoelectric conversion unit 241a has a second feedback coil 241f corresponding to the first feedback coil 231f, and a second shunt resistor 241h corresponding to the first shunt resistor 231h.

[0057] The second processing circuit 241b has a second adjusting amplifier 241j corresponding to the first adjusting amplifier 231j and a second threshold power supply 241k corresponding to the first threshold power supply 231k. The second filter 242 has a second resistor 242a corresponding to the first resistor 232a and a second capacitor 242b corresponding to the first capacitor 232b. As shown in Figure 8, the wiring board 20 has a second power supply wiring 242c corresponding to the first power supply wiring 232c, a second output wiring 242d corresponding to the first output wiring 232d, and a second ground wiring 242e corresponding to the first ground wiring 232e. The second ASIC 241 is connected to the second power supply wiring 242c, the second output wiring 242d, and the second ground wiring 242e, respectively. The output terminal of the second adjusting amplifier 241j of the second ASIC 241 is connected to the second output wiring 242d.

[0058] The second resistor 242a of the second filter 242 is provided on the second output wiring 242d. The second capacitor 242b connects the second output wiring 242d and the second ground wiring 242e. As a result, the second filter 242 of the second sensing unit 24 constitutes a low-pass filter with the second resistor 242a and the second capacitor 242b. The output of the second ASIC 241 is output to the battery ECU 200 via this low-pass filter. As a result, the second sensing unit 24 outputs a signal from which high-frequency noise has been removed to the battery ECU 200. In this way, the second sensing unit 24 also outputs an electrical signal corresponding to the DC current flowing through the conductive busbar 50 as a magnetic detection signal to the battery ECU 200.

[0059] The second processing circuit 241b, like the first processing circuit 231b, has a non-volatile memory that stores the relationship between the temperature and resistance of the magnetoresistive element. The second processing circuit 241b may adjust the gain and offset of the second adjustment amplifier 241j by rewriting the information stored in the non-volatile memory based on the temperature information detected by the first thermistor 71 and the second thermistor 72. This makes it possible to correct fluctuations in the output of the second adjustment amplifier 241j caused by temperature changes.

[0060] Furthermore, the first one-sided element 231c, the first other-sided element 231d, the second one-sided element 241c, and the second other-sided element 241d constituting the full-bridge circuit do not all have to be magnetoresistive elements. The full-bridge circuit only needs to have at least one of the first one-sided element 231c, the first other-sided element 231d, the second one-sided element 241c, and the second other-sided element 241d be a magnetoresistive element. Alternatively, it may consist of only one half-bridge circuit instead of a full-bridge circuit. Also, if the above-mentioned redundancy is not required by the first sensing unit 23 and the second sensing unit 24, the current detection device 1 may adopt a configuration having only one of the first sensing unit 23 and the second sensing unit 24.

[0061] The third sensing unit 25 is mainly composed of ICs and a microcontroller, and includes a CPU, ROM, flash memory, RAM, I / O, drive circuit, AD converter, low-pass filter, communication circuit, and bus lines connecting these components. The ROM stores the temperature coefficient of resistance, which shows the relationship between the electrical resistance value of the conductive busbar 50, which changes with temperature, and the temperature. The third sensing unit 25 calculates the current flowing through the conductive busbar 50 based on the voltage value of the conductive busbar 50 and the temperature of the conductive busbar 50. IC, I / O, and AD are abbreviations for Integrated Circuit, Input / Output, and Analog-Digital, respectively. The ROM and RAM of the third sensing unit 25 are composed of non-transitional physical storage media.

[0062] As shown in Figures 6, 7, and 9, the third sensing unit 25 is electrically connected to the conductive busbar 50 via a connection part 60 for connecting the wiring board 20 and the conductive busbar 50. The third sensing unit 25 is also electrically connected to the first thermistor 71 and the second thermistor 72 via the wiring pattern of the wiring board 20. Therefore, the third sensing unit 25, the first thermistor 71, and the second thermistor 72 are electrically connected to each other. The connection part 60 has a first connection pin 61 and a second connection pin 62. The sides of the first connection pin 61 and the second connection pin 62 that connect to the wiring board 20 are inserted into through-holes formed through the wiring board 20 and fixed with solder (not shown).

[0063] The third sensing unit 25 detects the voltage applied to one side of the conductive busbar 50 in the second direction D2 via the first connection pin 61, and detects the voltage applied to the other side of the conductive busbar 50 in the second direction D2 via the second connection pin 62. The third sensing unit 25 also acquires signals from the first thermistor 71 and the second thermistor 72 via the wiring pattern of the wiring board 20. That is, the third sensing unit 25 acquires temperature detection signals from the first thermistor 71 and the second thermistor 72 corresponding to the temperature of the conductive busbar 50.

[0064] <Thermistors> The first thermistor 71 and the second thermistor 72 are temperature detection units that detect the temperature of the conductive busbar 50. As shown in Figures 7 and 9, the first thermistor 71 and the second thermistor 72 are mounted on the busbar-facing surface 22 of the wiring board 20. The first thermistor 71 detects the temperature of the conductive busbar 50 via the first connection pin 61. The second thermistor 72 detects the temperature of the conductive busbar 50 via the second connection pin 62. The first thermistor 71 and the second thermistor 72 output an electrical signal corresponding to the detected temperature of the conductive busbar 50 as a temperature detection signal to the third sensing unit 25. The third sensing unit 25 corresponds to a current detection unit that outputs a current detection signal corresponding to the current flowing through the conductive busbar 50.

[0065] As shown in Figures 9 and 10, the conductive busbar 50 has a flat, plate-like shape that extends in a second direction D2 and has a thin thickness in a third direction D3. The conductive busbar 50 is made of a conductive material such as copper, brass, or aluminum. The conductive busbar 50 can be manufactured, for example, by press-forming a plate. Alternatively, the conductive busbar 50 may be manufactured by integrally connecting multiple plates, or by welding multiple plates. Alternatively, the conductive busbar 50 can be manufactured by pouring molten conductive material into a mold. The method of manufacturing the conductive busbar 50 is not particularly limited.

[0066] The conductive busbar 50 has a busbar surface 51 on one side in the third direction D3 and a busbar back surface 52 on the other side in the third direction D3. Furthermore, as shown by the two dashed lines in Figure 10, the conductive busbar 50 has a covering portion 53 that covers the sensor housing 10, and a first exposed portion 54 and a second exposed portion 55 that are exposed from the sensor housing 10. The first exposed portion 54 and the second exposed portion 55 are aligned in the second direction D2 via the covering portion 53. The first exposed portion 54 and the second exposed portion 55 are integrally connected via the covering portion 53. The covering portion 53, the first exposed portion 54, and the second exposed portion 55 have a constant size in the third direction D3 relative to each other. That is, the distance between the busbar surface 51 and the busbar back surface 52 of the conductive busbar 50 is constant from one end to the other end in the second direction D2.

[0067] The first exposed portion 54 has a first connection hole 541 into which a bolt for attaching the current detection device 1 is inserted. The first connection hole 541 is formed to penetrate the first exposed portion 54 in the third direction D3. The second exposed portion 55 has a second connection hole 551 into which a bolt for attaching the current detection device 1 is inserted. The second connection hole 551 is formed to penetrate the second exposed portion 55 in the third direction D3. The conductive busbar 50 is electrically and mechanically connected to the mounting target by inserting bolts into the first connection hole 541 and bolts into the second connection hole 551, and by tightening nuts from the tip side of the shafts of these bolts toward the head side. In this embodiment, the conductive busbar 50 is configured such that the first exposed portion 54 side is connected to the battery VT and the second exposed portion 55 side is connected to the energized busbar BU, allowing current to flow from the battery VT to the inverter INV.

[0068] As shown in Figure 10, the covering portion 53 has a locally shorter constricted portion 531 in the length of the first direction D1. The constricted portion 531 in this embodiment is less than half the size of the first exposed portion 54 and the second exposed portion 55 in the length of the first direction D1. The covering portion 53 and the constricted portion 531 have a line-symmetric shape with respect to the axis of symmetry AS, which is a center line passing through the center point CP in the first direction D1. The center point CP is equivalent to the centroid of the covering portion 53.

[0069] Furthermore, the length of the constricted portion 531 in the first direction D1 may be progressively shortened. Specifically, in the second direction D2, the length of the constricted portion 531 in the first direction D1 may be progressively shortened as you move from the first exposed portion 54 towards the center point CP, and the length of the constricted portion 531 in the first direction D1 may be progressively shortened as you move from the second exposed portion 55 towards the center point CP. In this case, the length of the constricted portion 531 in the first direction D1 may be shortened in multiple stages, such as in two stages. Alternatively, the length of the constricted portion 531 in the first direction D1 may be continuously shortened.

[0070] The length of the constricted portion 531 in the first direction D1 is shorter than that of the first exposed portion 54 and the second exposed portion 55, respectively. Therefore, the current density flowing through the constricted portion 531 is higher than that of the currents flowing through the first exposed portion 54 and the second exposed portion 55. As a result, the strength of the magnetic field under test emitted from the current flowing through the constricted portion 531 is higher than that of the magnetic field under test emitted from the currents flowing through the first exposed portion 54 and the second exposed portion 55.

[0071] Furthermore, as shown in Figure 9, the first sensing unit 23 and the second sensing unit 24 are arranged on the wiring board 20 and are positioned opposite the constricted portion 531, separated in the third direction D3. Therefore, the high-intensity magnetic field to be measured, generated from the current flowing through the constricted portion 531, is transmitted through each of the first sensing unit 23 and the second sensing unit 24.

[0072] As described above, the conductive busbar 50 extends in the second direction D2. Current flows through the conductive busbar 50 in the second direction D2. This flow of current in the second direction D2 generates a magnetic field under test in the circumferential direction around the second direction D2, following Ampère's law. The magnetic field under test flows in a ring shape around the conductive busbar 50 in the plane defined by the first direction D1 and the third direction D3. The first sensing unit 23 and the second sensing unit 24 detect the component of the magnetic field under test that is aligned with the first direction D1. Specifically, when current flows from one side to the other in the second direction D2 of the conductive busbar 50, the first sensing unit 23 and the second sensing unit 24 detect the magnetic flux that flows from one side to the other in the first direction D1, which is generated by the right-hand rule.

[0073] As shown by the dashed line in Figure 10, the first magnetoelectric conversion unit 231a of the first sensing unit 23 and the second magnetoelectric conversion unit 241a of the second sensing unit 24 are aligned in the second direction D2. These first magnetoelectric conversion units 231a and the second magnetoelectric conversion unit 241a are symmetrically arranged with respect to the axis of symmetry AS. Furthermore, the position in the first direction D1 of each of the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a is the same as the position in the first direction D1 of the center point CP passing through the axis of symmetry AS. Therefore, the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are aligned in the second direction D2 with respect to the center point CP.

[0074] Furthermore, the separation distance in the third direction D3 between the first magnetoelectric conversion section 231a and the second magnetoelectric conversion section 241a and the covering section 53 is the same. As described above, the covering section 53 and the constricted section 531 have a line-symmetric shape with respect to the axis of symmetry AS. As a result, the magnetic field to be measured, with a component in the first direction D1 being equivalent, is transmitted through the first magnetoelectric conversion section 231a and the second magnetoelectric conversion section 241a. In other words, the intensity and magnetic flux density of the magnetic field transmitted through the first magnetoelectric conversion section 231a and the second magnetoelectric conversion section 241a are the same.

[0075] Therefore, the electrical signal input to the battery ECU 200 from the first sensing unit 23 and the electrical signal input to the battery ECU 200 from the second sensing unit 24 are identical. The battery ECU 200 compares these two input electrical signals to determine whether or not an abnormality has occurred in either the first sensing unit 23 or the second sensing unit 24. In this way, the current detection device 1 according to this embodiment has redundancy. The first sensing unit 23 and the second sensing unit 24 correspond to magnetic detection units that output a magnetic field detection signal corresponding to the magnetic field being measured, which is generated when current flows through the conductive busbar 50.

[0076] Furthermore, as shown in Figure 9, the conductive busbar 50 has a first connecting pin 61 and a second connecting pin 62 connected to the busbar surface 51 on the side facing the wiring board 20 in the third direction D3. The conductive busbar 50, the first connecting pin 61, and the second connecting pin 62 are fixed to each other, for example, by welding. As a result, the conductive busbar 50 is electrically and mechanically connected to the first connecting pin 61 and the second connecting pin 62.

[0077] The first connection pin 61 is made of a conductive material such as copper or gold and is formed in a rod shape. The first connection pin 61 has a first connection support portion 611 that is connected to the busbar surface 51 and a first connection detection portion 612 that is connected to the wiring board 20. The first connection pin 61 is formed by integrally forming the first connection support portion 611 and the first connection detection portion 612 and bending it. The first connection detection portion 612 is formed extending along the third direction D3, with one end communicating with the first connection support portion 611 and the other end being inserted into a through-hole formed through the wiring board 20 and protruding from the shield-facing surface 21 of the wiring board 20. The first connection detection portion 612 is also connected to the wiring board 20 by solder.

[0078] The second connecting pin 62 is made of a conductive material such as copper or gold and is formed in a rod shape. The second connecting pin 62 has a second connecting support portion 621 that is connected to the busbar surface 51 and a second connecting detection portion 622 that is connected to the wiring board 20. The second connecting pin 62 is formed by integrally forming the second connecting support portion 621 and the second connecting detection portion 622 and bending it. The second connecting detection portion 622 is formed extending along the third direction D3, with one end communicating with the second connecting support portion 621 and the other end being inserted into a through-hole formed through the wiring board 20 and protruding from the shield-facing surface 21 of the wiring board 20. The second connecting detection portion 622 is also connected to the wiring board 20 by solder.

[0079] <Shielding> The first shield 30 and the second shield 40 shown in Figures 3 and 11 are shielding parts made of a material with higher magnetic permeability than the sensor housing 10. Therefore, electromagnetic noise, which is external noise that tries to penetrate from the outside to the inside of the current detection device 1, actively tries to pass through the first shield 30 and the second shield 40. This makes it possible to suppress the input of electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. Electromagnetic noise is a factor that adds noise components to the magnetic field detection signals output by the first sensing unit 23 and the second sensing unit 24. In other words, electromagnetic noise input to the first sensing unit 23 and the second sensing unit 24 is a factor that reduces the detection accuracy when the current detection device 1 detects current.

[0080] The first shield 30 and the second shield 40 suppress the input of electromagnetic noise that would reduce the detection accuracy of the current detection device 1. As shown in Figure 11, the first shield 30 and the second shield 40 are arranged to sandwich a part of the conductive busbar 50 and the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a from both sides in the third direction D3. Furthermore, the first shield 30 and the second shield 40 are arranged so that the centers of their respective first directions D1 overlap in the third direction D3.

[0081] Furthermore, the conductive busbar 50 is positioned such that the center of the first direction D1 coincides with the center of the first direction D1 of the first shield 30 and the second shield 40 in the third direction D3. In addition, the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are positioned such that the centers of the first direction D1 of the first shield 30 and the second shield 40 coincide with the center of the first direction D1 of the first shield 30 and the second shield 40 in the third direction D3. In other words, the conductive busbar 50, the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are positioned symmetrically with respect to a virtual line VL that passes through the center of the first direction D1 of the first shield 30 and the second shield 40 and lies along the third direction D3.

[0082] The first shield 30 and the second shield 40 form an annular magnetic circuit surrounding a part of the conductive busbar 50 and the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. The magnetic circuit formed by the first shield 30 and the second shield 40 is a closed magnetic path surrounding the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. Hereinafter, the magnetic circuit formed by the first shield 30 and the second shield 40 will be referred to as the shield magnetic circuit.

[0083] As shown in Figure 11, the first shield 30 and the second shield 40 each have a plate shape with a thin thickness in the third direction D3. As shown in Figures 12 and 13, the first shield 30 has a first surface 31 on one side in the third direction D3 and a first back surface 32 on the other side in the third direction D3. As shown in Figures 14 and 15, the second shield 40 has a second surface 41 on the other side in the third direction D3 and a second back surface 42 on one side in the third direction D3.

[0084] As shown in Figure 11, the first shield 30 and the second shield 40 are provided on the sensor housing 10 such that the first back surface 32 and the second back surface 42 face each other in a third direction D3 via a conductive busbar 50. The first shield 30 has a first surface 31 that is exposed to the outside of the sensor housing 10. The second shield 40 has a second surface 41 that is exposed to the outside of the sensor housing 10. These first surface 31 and second surface 41 each constitute a part of the outermost surface of the current detection device 1. The first back surface 32 corresponds to the first opposing surface facing the second shield 40. The second back surface 42 corresponds to the second opposing surface facing the first shield 30. The third direction D3 corresponds to the opposing direction in which the first shield 30 and the second shield 40 face each other.

[0085] <Second Shield> As shown in Figures 14 and 15, the second shield 40 has a planar shape that, when viewed along the third direction D3, is a rectangle with the first direction D1 as its extension. Furthermore, in a view along the second direction D2, the second shield 40 is formed by folding each end of a thin, flat member in the third direction D3 toward one side of the third direction D3 in the direction of the first direction D1. In Figures 14 and 15, in order to clarify the boundary between the center and both ends of the second shield 40 in the second direction D2, these boundaries between the center and both ends are shown by two dashed lines extending in the first direction D1.

[0086] As shown in Figures 14 and 15 below, the central portion of the second shield 40 in the second direction D2 is referred to as the second central portion 43, and the portions at both ends of the second shield 40 in the second direction D2 are referred to as the second ends 44. The second central portion 43 is located in the second direction D2 between the ends of each of the two second ends 44. That is, the two second ends 44 are aligned in the second direction D2 via the second central portion 43. The two second ends 44 are integrally connected via the second central portion 43. Furthermore, the length of the two second ends 44 in the first direction D1 is shorter than that of the second central portion 43. In other words, the size of the second central portion 43 in the first direction D1 is larger than that of each of the two second ends 44.

[0087] As shown in Figure 16, the second shield 40 of this embodiment can be manufactured by laminating and bonding multiple flat plate members made of a soft magnetic material with high magnetic permeability, such as permalloy. When the second shield 40 is attached to the sensor housing 10, the multiple flat plates made of the soft magnetic material are arranged in the third direction D3. In this embodiment, rolled electromagnetic steel sheets are used as the flat plate members constituting the second shield 40, and the second shield 40 is formed by laminating five electromagnetic steel sheets.

[0088] The five electromagnetic steel sheets constituting the second shield 40 include ferromagnetic materials and non-magnetic materials that do not exhibit ferromagnetism. The electromagnetic steel sheets made of non-magnetic materials are positioned at any of the five electromagnetic steel sheets stacked in the third direction D3, excluding both ends of the third direction D3. The electromagnetic steel sheets made of magnetic materials are formed from materials such as iron (Fe), nickel (Ni), cobalt (Co), permalloy (Ni-Fe alloy), and ferrite. The electromagnetic steel sheets made of non-magnetic materials are formed from materials such as aluminum (Al), copper (Cu), and epoxy resin.

[0089] When manufacturing the second shield 40 by laminating flat plate members formed by rolling electrical steel sheets, the direction in which each of the five electrical steel sheets is stretched by the rolling process is set, for example, to be the first direction D1 when the second shield 40 is attached to the sensor housing 10. As a result, the atomic arrangement of each electrical steel sheet constituting the second shield 40 is aligned in the first direction D1. Consequently, the permeability of the second shield 40 is higher in the first direction D1 than in the second direction D2. By specifying the rolling direction of the electrical steel in this way, anisotropy can be introduced into the permeability of the second shield 40.

[0090] Furthermore, by aligning the atomic arrangement of each electromagnetic steel sheet constituting the second shield 40 in the first direction D1, the input of magnetic flux between these stacked electromagnetic steel sheets can be suppressed. Specifically, among the five electromagnetic steel sheets stacked in the second shield 40, the input of magnetic flux from one electromagnetic steel sheet to another that is adjacent to each other in the third direction D3 is suppressed. As a result, the magnetic flux input to each electromagnetic steel sheet constituting the second shield 40 is less likely to be guided in the third direction D3, thus suppressing its input to an electromagnetic steel sheet other than the one that input it, and promoting the flow of magnetic flux in the first direction D1.

[0091] Hereinafter, as shown in Figure 16, the five electromagnetic steel plates constituting the second shield 40 may be referred to as the 2-1 steel plate 40a, 2-2 steel plate 40b, 2-3 steel plate 40c, 2-4 steel plate 40d, and 2-5 steel plate 40e in the order they are arranged from one side to the other in the third direction D3. Also, the 2-1 steel plate 40a, 2-2 steel plate 40b, 2-3 steel plate 40c, 2-4 steel plate 40d, and 2-5 steel plate 40e may be collectively referred to as the 2-1 steel plate 40a to the 2-5 steel plate 40e. The 2-1 steel plate 40a to the 2-5 steel plate 40e are made up of thin plate members with equal thickness. The second-first steel sheet 40a is an electromagnetic steel sheet located at the other end of the third direction D3 among the five electromagnetic steel sheets, forming the second surface 41, and constituting a part of the outermost surface of the current detection device 1. The second-fifth steel sheet 40e is an electromagnetic steel sheet located at one end of the third direction D3 among the five electromagnetic steel sheets, forming the second back surface 42, and facing the conductive busbar 50.

[0092] Furthermore, as shown in Figures 14 and 15, the second shield 40 has two second edges 45 aligned in the first direction D1. The second shield 40 has a second extension 46 formed on each of the two second edges 45 on the second central portion 43 side, extending in the third direction D3. As shown in Figures 11, 14, and 15, these two second extensions 46 are connected to the second central portion 43 and extend in the direction from the second surface 41 to the second back surface 42 in the third direction D3. That is, the second extensions 46 extend toward the first shield 30. For this reason, one side of the second extension 46 in the third direction D3 is positioned toward the first shield 30 than the second central portion 43. The second extension 46 forms a rectangular parallelepiped with the second direction D2 as its extension direction.

[0093] Furthermore, these two second extensions 46 protrude from the second end 44 in the first direction D1. Specifically, of the two second extensions 46, the second extension 46 connected to one side of the second central portion 43 in the first direction D1 protrudes from each of the two second end 44 to one side of the first direction D1. Also, of the two second extensions 46, the second extension 46 connected to the other side of the second central portion 43 in the first direction D1 protrudes from each of the two second end 44 to the other side of the first direction D1. The two second extensions 46 are identical in shape and size, and their dimensions in the first direction D1, second direction D2, and third direction D3 are equal.

[0094] The second extension 46 is formed by bending the second shield 40, which is formed by laminating a plurality of flat plate members made of soft magnetic material as described above. Specifically, as shown in Figure 16, the second extension 46 is formed by laminating some of the steel plates from the second-first steel plate 40a to the second-fifth steel plate 40e that are formed by bending. In this embodiment, the second-second steel plate 40b to the second-fifth steel plate 40e are formed by bending both ends in the first direction D1 toward one side in the third direction D3. In contrast, the second-first steel plate 40a is formed in a thin plate shape extending in the first direction D1 and the second direction D2, and both ends in the first direction D1 are not bent.

[0095] The second extension portion 46 is formed by the overlapping bent portions of the second-2 steel plates 40b to the second-5 steel plates 40e, which are stacked in the third direction D3. The second-5 steel plate 40e is positioned on the other side of the second-4 steel plate 40d in the third direction D3, at a location that does not overlap with the bent portions of the second-1 steel plates 40a to the second-4 steel plates 40d in the third direction D3. The second central portion 43 is formed by the overlapping portions of the second-1 steel plates 40a to the second-5 steel plates 40e, which are stacked in the third direction D3, extending in the first direction D1 and the second direction D2, respectively.

[0096] In their pre-bending state, each of the 2-1 steel plates 40a to 2-4 steel plates 40d has a portion that forms the second extension 46 connected to a portion that forms the second central portion 43, and protrudes to one side and the other side in the first direction D1 from the portion that forms the second end portion 44. The second extension 46 is formed when these portions that protrude to one side and the other side in the first direction D1 are bent toward one side in the third direction D3. In the 2-1 steel plate 40a to 2-4 steel plate 40d, the portions that form the second extension 46 extend toward the third direction D3.

[0097] Hereinafter, the portion of the steel plate 2-2 40b that forms the second extension portion 46 will be referred to as the 2-2 extension portion 46b, and the portion of the steel plate 2-3 40c that forms the second extension portion 46 will be referred to as the 2-3 extension portion 46c. Furthermore, the portion of the steel plate 2-4 40d that forms the second extension portion 46 will be referred to as the 2-4 extension portion 46d, and the portion of the steel plate 2-5 40e that forms the second extension portion 46 will be referred to as the 2-5 extension portion 46e. In some cases, the 2-2 extension portion 46b, the 2-3 extension portion 46c, the 2-4 extension portion 46d, and the 2-5 extension portion 46e will be collectively referred to as the 2-2 extension portion 46b to the 2-5 extension portion 46e.

[0098] Furthermore, the portion of the 2-1 steel plate 40a that forms the second central portion 43 is referred to as the 2-1 central portion 43a, and the portion of the 2-2 steel plate 40b that forms the second central portion 43 is referred to as the 2-2 central portion 43b. Also, the portion of the 2-3 steel plate 40c that forms the second central portion 43 is referred to as the 2-3 central portion 43c, the portion of the 2-4 steel plate 40d that forms the second central portion 43 is referred to as the 2-4 central portion 43d, and the portion of the 2-5 steel plate 40e that forms the second central portion 43 is referred to as the 2-5 central portion 43e. In some cases, the 2-1 central portion 43a, 2-2 central portion 43b, 2-3 central portion 43c, 2-4 central portion 43d, and 2-5 central portion 43e are collectively referred to as the 2-1 central portion 43a to the 2-5 central portion 43e. In this embodiment, the second-fifth steel plate 40e does not have a portion that forms the second extension portion 46, and is composed only of the second-fifth central portion 43e.

[0099] The second central section 43 is formed by stacking the second-first central section 43a to the second-fifth central section 43e in the third direction D3. The second extension section 46 is formed by overlapping the second-second extension section 46b to the second-fifth extension section 46e in the first direction D1. Furthermore, the second-second extension section 46b to the second-fifth extension section 46e are formed such that when the second-second steel plate 40b to the second-fifth steel plate 40e are stacked, the positions of one end of each in the third direction D3 overlap.

[0100] Here, each of the 2-2 steel plates 40b to 2-5 steel plates 40e in this embodiment is made of thin plate members with equal thickness. The 2-2 extensions 46b to 2-5 extensions 46e, which are formed by bending the 2-2 steel plates 40b to 2-5 steel plates 40e, have different dimensions extending in the third direction D3. Specifically, the dimensions in the third direction D3 increase in the order of 2-2 extension 46b, 2-3 extension 46c, 2-4 extension 46d, and 2-5 extension 46e. In other words, among the second-second extension section 46b to the second-fifth extension section 46e, the dimension in the third direction D3 is smallest for the second-fifth extension section 46e, which is located furthest inward, and the dimension in the third direction D3 is largest for the second-second extension section 46b, which is located furthest out.

[0101] The two second extensions 46 formed in this manner have equal dimensions in the first direction D1. The second central portion 43 is larger than the dimensions in the first direction D1 of each of the two second extensions 46. Furthermore, the cross-sectional area of ​​the second shield 40 perpendicular to the first direction D1 in the second central portion 43 is larger than the cross-sectional area of ​​the second extensions 46 in the third direction D3.

[0102] Furthermore, the two second extensions 46 are spaced apart from each other and facing each other in the first direction D1. The inner surfaces of the two second-fifth extensions 46e are spaced apart from each other and facing each other in the first direction D1. A portion of the conductive busbar 50 is arranged in the space between the two second extensions 46, as well as the magnetic detection element of the first magnetoelectric conversion unit 231a and the magnetic detection element of the second magnetoelectric conversion unit 241a. That is, a portion of the conductive busbar 50 is arranged in the space formed between the inner surfaces of each of the two second-first extensions 46a, as well as the magnetic detection element of the first magnetoelectric conversion unit 231a and the magnetic detection element of the second magnetoelectric conversion unit 241a.

[0103] <First Shield> As shown in Figures 12 and 13, the first shield 30 has a planar shape in a direction view along the third direction D3 that is a rectangle with the first direction D1 as its extension. The first shield 30 is also formed as a flattened rectangular parallelepiped with a thin thickness in the third direction D3. In this embodiment, the first shield 30 has notches 33 formed at the four corners. In Figures 12 and 13, in order to clarify the boundary between the center and both ends of the first shield 30 in the second direction D2, these boundaries between the center and both ends are shown by two dashed lines extending in the first direction D1. Hereinafter, as shown in Figures 12 and 13, the central part of the first shield 30 in the second direction D2 is shown as the first central part 34, and the parts of the first shield 30 in the second direction D2 are shown as the first ends 35, respectively.

[0104] The first central portion 34 is located in the second direction D2 between the two ends of the first end portion 35. That is, the two first end portions 35 are aligned in the second direction D2 via the first central portion 34. The two first end portions 35 are integrally connected via the first central portion 34. The length of the two first end portions 35 in the first direction D1 is shorter than that of the first central portion 34. In other words, the size of the first central portion 34 in the first direction D1 is larger than that of each of the two first end portions 35.

[0105] As shown in Figure 17, the first shield 30 of this embodiment can be manufactured by laminating and bonding multiple flat plate members made of a soft magnetic material with high magnetic permeability, such as permalloy, similar to the second shield 40. When the first shield 30 is attached to the sensor housing 10, the multiple flat plate members made of the soft magnetic material are arranged in the third direction D3. In this embodiment, rolled electromagnetic steel sheets are used as the flat plate members constituting the first shield 30, and the first shield 30 is formed by laminating five electromagnetic steel sheets. The electromagnetic steel sheets constituting the first shield 30 may be made of the same material as the electromagnetic steel sheets constituting the second shield 40, or they may be made of different materials than the electromagnetic steel sheets constituting the second shield 40.

[0106] When the first shield 30 is manufactured by laminating flat plate members formed by rolling electrical steel sheets, the direction in which each of the five electrical steel sheets is stretched by the rolling process is set to coincide with the magnetic anisotropy of the second shield 40. For example, as described above, the magnetic anisotropy when the second shield 40 is attached to the sensor housing 10 is set to be the first direction D1. In this case, the direction in which each of the electrical steel sheets constituting the first shield 30 is stretched is set to be the first direction D1 when the first shield 30 is attached to the sensor housing 10.

[0107] As a result, the atomic arrangement of each electrical steel sheet constituting the first shield 30 is aligned in the first direction D1. This makes it possible to match the magnetic permeability anisotropy of the first shield 30 with that of the second shield 40. Furthermore, similar to the second shield 40, the magnetic permeability of the first shield 30 is higher in the first direction D1 than in the second direction D2.

[0108] Furthermore, by aligning the atomic arrangement of each electromagnetic steel sheet constituting the first shield 30 in the first direction D1, the input of magnetic flux between these stacked electromagnetic steel sheets can be suppressed. Specifically, among the five electromagnetic steel sheets stacked in the first shield 30, the input of magnetic flux from one adjacent electromagnetic steel sheet to the other is suppressed. As a result, the magnetic flux input to each electromagnetic steel sheet constituting the first shield 30 is less likely to be guided in the third direction D3, thus suppressing its input to an electromagnetic steel sheet other than the one that input it, and promoting the flow of magnetic flux in the first direction D1.

[0109] Hereinafter, as shown in Figure 17, the five electromagnetic steel plates constituting the first shield 30 may be referred to as the 1-1 steel plate 30a, 1-2 steel plate 30b, 1-3 steel plate 30c, 1-4 steel plate 30d, and 1-5 steel plate 30e in the order they are arranged from one side to the other in the third direction D3. In addition, the 1-1 steel plate 30a, 1-2 steel plate 30b, 1-3 steel plate 30c, 1-4 steel plate 30d, and 1-5 steel plate 30e may be collectively referred to as the 1-1 steel plate 30a to the 1-5 steel plate 30e. The 1-1 steel plate 30a to the 1-5 steel plate 30e are all thin plate members with equal thickness, extending in the first direction D1 and the second direction D2. The first-first steel sheet 30a is an electromagnetic steel sheet located at one end of the third direction D3 among the five electromagnetic steel sheets, forming the first surface 31, and constitutes a part of the outermost surface of the current detection device 1. The first-fifth steel sheet 30e is an electromagnetic steel sheet located at the other end of the third direction D3 among the five electromagnetic steel sheets, forming the first back surface 32, and faces the wiring board 20.

[0110] Furthermore, the first shield 30 has two first edges 36 aligned in the first direction D1. The first shield 30 has first extensions 37 formed on the first central portion 34 side of each of these two first edges 36, extending in the first direction D1. These two first extensions 37 are connected to the first central portion 34. The first extensions 37 form a rectangular parallelepiped with the second direction D2 as its extension direction.

[0111] Furthermore, these two first extensions 37 protrude from the first end 35 in the first direction D1. Specifically, of the two first extensions 37, the first extension 37 connected to one side of the first central portion 34 in the first direction D1 protrudes from each of the two first end 35 to one side of the first direction D1. Also, of the two first extensions 37, the first extension 37 connected to the other side of the first central portion 34 in the first direction D1 protrudes from each of the two first end 35 to the other side of the first direction D1. The two first extensions 37 are identical in shape and size, and their dimensions in the first direction D1 and the second direction D2 are identical.

[0112] In this embodiment, the first shield 30 has a size in the first direction D1 that is smaller than the size in the first direction D1 of the second shield 40. Furthermore, the two first extensions 37 are formed so that not all of them face the second extension 46 in the third direction D3. Specifically, the first extension 37 that protrudes to one side in the first direction D1 has a part of its other side surface in the third direction D3 that does not face the one side surface in the third direction D3 of the second extension 46 that protrudes to one side in the first direction D1. Also, the first extension 37 that protrudes to the other side in the first direction D1 has a part of its other side surface in the third direction D3 that does not face the one side surface in the third direction D3 of the second extension 46 that protrudes to the other side in the first direction D1.

[0113] Furthermore, as shown in Figure 11 and other figures, the first shield 30 has a recessed back surface portion 321 formed on the other side of the third direction D3. The recessed back surface portion 321 is formed in a position that does not overlap with the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, which have magnetic detection elements, in the third direction D3. Specifically, one recessed back surface portion 321 is formed at each end of the first back surface 32 in the first direction D1, and another at the other end. These two recessed back surface portions 321 are formed recessed from the first back surface 32 toward the first surface 31. Also, as shown in Figure 18, the two recessed back surface portions 321 are formed by cutting out at each end of the first back surface 32 in the first direction D1, from one end to the other end in the second direction D2. The space formed by the recessed back surface portion 321 forms a rectangular parallelepiped with the second direction D2 as its extension direction.

[0114] Here, the first shield 30 is formed by laminating 1-1 steel plates 30a to 1-5 steel plates 30e, which are made of a soft magnetic material, as described above. In this embodiment, each of the 1-1 steel plates 30a to 1-5 steel plates 30e has a thickness equal to the other, which is the size in the third direction D3. Also, each of the 1-1 steel plates 30a to 1-4 steel plates 30d has a size equal to the other in the first direction D1. In contrast, among the 1-1 steel plates 30a to 1-5 steel plates 30e, the size in the first direction D1 of the 1-5 steel plate 30e is smaller than the size in the first direction D1 of each of the 1-1 steel plates 30a to 1-4 steel plates 30d. By reducing the size in the first direction D1 of the 1-5 steel plate 30e in this way, a recess 321 is formed on the back side of the first shield 30.

[0115] As shown in Figures 17 and 18, the recessed portion 321 on the back side is realized by the 1-5 steel plate 30e, which is closest to the 2-5 steel plate 40e, among the 1-1 steel plates 30a to 1-5 steel plates 30e that are laminated. Specifically, the recessed portion 321 on the back side is formed by cutting out the 1-5 steel plate 30e, which is closest to the 2-1 extension portion 46a that extends toward the first shield 30, among the 1-1 steel plates 30a to 1-5 steel plates 30e that are laminated. The two recessed portions 321 on the back side formed on the first shield 30 in this embodiment are formed by cutting out the ends of the 1-5 steel plate 30e on one side and the other side in the first direction D1.

[0116] As a result, the dimension of the first-fifth steel plate 30e in the first direction D1 is smaller than the dimension of the first-fifth steel plate 30a to the first-fourth steel plate 30d in the first direction D1. The first-fifth steel plate 30e is positioned in the center of the first direction D1 on the other side of the first-fourth steel plate 30d in the third direction D3. For this reason, the back-side recesses 321 formed at the ends on one and the other sides of the first direction D1 have equal dimensions in the first direction D1.

[0117] The first shield 30 formed in this manner is separated from the second shield 40 by a greater distance compared to the case where the ends of the first-fifth steel plate 30e in the first direction D1 are not cut out. Specifically, the first shield 30 is separated from the end of the first-fifth steel plate 30e in the first direction D1 by a greater distance compared to the case where the back surface recess 321 is not formed on the first back surface 32 by a greater distance compared to the case where first shield 30 is separated from the end of the first-fifth steel plate 30e in the first direction D1 by a greater distance compared to the case where the back surface recess 321 is not formed on the first back surface 32 by a greater distance compared to the case where the first shield 30 is separated from the end of the first-fifth steel plate 30e in the first direction D1 by a greater distance compared to the case where the end of the first-fifth steel plate 30e in the first direction D1 by a greater distance compared to the case where the end of the first-fifth steel plate Furthermore, the distance between these first-fifth steel plates 30e and the second extension 46 is greater than the distance between the first-fourth steel plate 30d and the second extension 46.

[0118] The above describes the configuration of the current detection device 1 in this embodiment. In the current detection device 1 configured in this way, as shown by the arrows in Figure 19, when a current in the second direction D2 flows through the conductive busbar 50, the first sensing unit 23, the second sensing unit 24, and the third sensing unit 25 each output a detection signal corresponding to the flowing current. Specifically, when a current flows through the conductive busbar 50, the third sensing unit 25 acquires temperature detection signals from the first thermistor 71 and the second thermistor 72, respectively.

[0119] The third sensing unit 25 then corrects the electrical resistance of the conductive busbar 50 based on the acquired temperature detection signal and the temperature coefficient of resistance, which is stored in the RAM and shows the relationship between the electrical resistance of the conductive busbar 50 and temperature. The third sensing unit 25 then uses the corrected electrical resistance of the conductive busbar 50 and the voltage values ​​applied to one side and the other side of the conductive busbar 50 in the second direction D2 to calculate the current flowing through the conductive busbar 50 based on Ohm's law. The third sensing unit 25 outputs a detection signal corresponding to the calculated current value as a current detection signal.

[0120] Furthermore, the first sensing unit 23 and the second sensing unit 24 detect the annular magnetic field generated around the conductive busbar 50 according to Ampere's law when current flows through the conductive busbar 50. The first sensing unit 23 and the second sensing unit 24 output a detection signal corresponding to the magnetic flux directed from one side to the other in the first direction D1, which is generated when a magnetic field is generated around the conductive busbar 50, as a magnetic detection signal corresponding to the current flowing through the conductive busbar 50. This allows the current flowing through the conductive busbar 50 to be detected.

[0121] However, if electromagnetic noise passing from outside to inside the current detection device 1 is input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, noise components will be added to the magnetic field detection signals output by the first sensing unit 23 and the second sensing unit 24. This may reduce the detection accuracy of the current value of the conductive busbar 50 calculated by the current detection device 1 based on the magnetic detection signal. For this reason, in the current detection device 1 of this embodiment, as described above, the first shield 30 and the second shield 40 are arranged to sandwich the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a from both sides in the third direction D3. This suppresses the input of electromagnetic noise from the outside to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, thereby suppressing a decrease in the detection accuracy of the current detection device 1.

[0122] Furthermore, the length of the first end 35 of the first shield 30 in the first direction D1 is shorter than that of the first central portion 34, which has first extensions 37 on both sides of the first direction D1. As a result, the permeability of the first end 35 in the first direction D1 is lower than that of the first central portion 34, making it difficult for a magnetic field to penetrate the first end 35. Consequently, the transmission of a magnetic field from one end of the first end 35 to the other via the portion of the first central portion 34 that is directly connected to the first end 35 and aligned in the second direction D2 is suppressed. This makes it difficult for a magnetic field to penetrate the portion of the first central portion 34 aligned with the first end 35 and the second direction D2. As a result, the portion of the first central portion 34 aligned in the second direction D2 is less likely to become magnetically saturated. The portion of the first central part 34 where magnetic saturation is suppressed, aligned in the second direction D2, and the first sensing unit 23 and the second sensing unit 24 mounted on the wiring board 20, are aligned in the third direction D3.

[0123] Furthermore, the length of the second end 44 of the second shield 40 in the first direction D1 is shorter than that of the second central portion 43. As a result, the permeability of the second end 44 in the first direction D1 is lower than that of the second central portion 43, making it difficult for a magnetic field to penetrate the second end 44. Consequently, the transmission of a magnetic field from one end of the second end 44 to the other via the portion of the second central portion 43 that is directly connected to the second end 44 and aligned in the second direction D2 is suppressed. This makes it difficult for a magnetic field to penetrate the portion of the second central portion 43 aligned with the second end 44 and the second direction D2. As a result, the portion of the second central portion 43 aligned in the second direction D2 is less likely to experience magnetic saturation. This portion of the second central portion 43 aligned in the second direction D2, where magnetic saturation is suppressed, and the first sensing unit 23 and the second sensing unit 24 mounted on the wiring board 20 are aligned in the third direction D3.

[0124] Therefore, the first shield 30 and the second shield 40 are designed to prevent a loss of sufficient suppression of external electromagnetic noise due to magnetic saturation.

[0125] Furthermore, as described above, the first shield 30 and the second shield 40 are provided on the sensor housing 10 in such a manner that the first back surface 32 and the second back surface 42 face each other in the third direction D3 via the wiring board 20. In this state provided on the sensor housing 10, the second extension portion 46 extends toward the first shield 30. The second extension portion 46 is positioned such that one side in the third direction D3 is toward the first shield 30 than the second central portion 43.

[0126] As a result, the separation distance in the third direction D3 between the first central portion 34 of the first shield 30 and the second extension portion 46 of the second shield 40 is shorter than the separation distance in the third direction D3 between the first back surface 32 of the first shield 30 and the second back surface 42 of the second shield 40. Therefore, magnetic fields that enter the first shield 30 can easily pass through to the second shield 40 via the second extension portion 46. Similarly, magnetic fields that enter the second shield 40 can easily pass through to the first shield 30 via the second extension portion 46.

[0127] As described above, the second extension portion 46 extends from the second central portion 43 side of the second end edge 45 to one side in the third direction D3. Furthermore, the second extension portion 46 is not formed on the second end 44 side of the second end edge 45. For this reason, the magnetic field that enters the first shield 30 can easily pass through the second extension portion 46 to the second central portion 43 of the second shield 40. This second central portion 43 and the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a mounted on the wiring board 20 face each other in the third direction D3.

[0128] Furthermore, the positions of the first magnetoelectric conversion section 231a and the second magnetoelectric conversion section 241a in the first direction D1 are located between the two second extensions 46 formed on each of the two second end edges 45. Therefore, when external noise along the first direction D1 attempts to pass through the region between the first back surface 32 and the second back surface 42, the external noise attempts to penetrate the second extensions 46 rather than the first magnetoelectric conversion section 231a and the second magnetoelectric conversion section 241a. The external noise that penetrates the second extensions 46 has its direction of transmission bent so that it can pass through the second shield 40. As a result, the transmission of external noise through the first magnetoelectric conversion section 231a and the second magnetoelectric conversion section 241a is suppressed.

[0129] Incidentally, the first shield 30 and the second shield 40 are arranged so as to sandwich a part of the conductive busbar 50. The first shield 30 and the second shield 40, arranged in this manner, form a shield magnetic circuit around the conductive busbar 50 through which the current flows. Therefore, when a magnetic field is generated around the conductive busbar 50 due to the flow of current through it, magnetic flux flows through the shield magnetic circuit. The magnetic flux flowing through the shield magnetic circuit flows in accordance with the magnetic field generated in a ring shape around the conductive busbar 50. Therefore, the magnetic flux flowing through the first shield 30 flows from one side to the other in the first direction D1. In contrast, the magnetic flux flowing through the second shield 40 flows from the other side to the one side in the first direction D1.

[0130] However, if magnetic flux flows through the first shield 30 and the second shield 40, causing at least one of them to become magnetically saturated, there is a risk that magnetic flux will leak from the shield magnetic circuit. When magnetic flux leaks from the shield magnetic circuit and this leaked magnetic flux is input as electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, it can cause a deterioration in the detection accuracy of the current detection device 1.

[0131] In contrast, as described above, the first shield 30 has a first end 35 that is shorter in the first direction D1 than the first central portion 34. Therefore, the magnetic flux input to the first shield 30 is less likely to pass through the first central portion 34 from one side to the other of the first end 35. Furthermore, the magnetic field to the first central portion 34 is less likely to pass through the portion of the first central portion 34 aligned with the first end 35 in the second direction D2, as shown by the dashed line in Figure 20. Similarly, the second shield 40 has a second end 44 that is shorter in the first direction D1 than the second central portion 43. Therefore, the magnetic flux input to the second shield 40 is less likely to pass through the second central portion 43 from one side to the other of the second end 44. Furthermore, the magnetic field to the second central portion 43 is less likely to pass through the portion of the second central portion 43 aligned with the second end 44 in the second direction D2.

[0132] Therefore, even if magnetic flux flows through the shield magnetic circuit due to current flowing through the conductive busbar 50, the first central portion 34 and the second central portion 43 are less likely to become magnetically saturated. As a result, leakage of magnetic flux from the shield magnetic circuit formed by the first shield 30 and the second shield 40 is suppressed.

[0133] However, as the current value of the current flowing through the conductive busbar 50 increases, the magnetic flux flowing through the shield magnetic circuit increases, making the first shield 30 and the second shield 40 more susceptible to magnetic saturation. For example, when magnetic flux flows through the shield magnetic circuit, the magnetic flux output from the second shield 40 and flowing to the first shield 30 tends to flow to areas that are close to the second shield 40. For this reason, the first back surface 32 of the first shield 30, which is the other side of the third direction D3 that is close to the second shield 40, is more susceptible to magnetic saturation. Similarly, the magnetic flux output from the first shield 30 and flowing to the second shield 40 tends to flow to areas that are close to the first shield 30. For this reason, the second back surface 42 of the second shield 40, which is the one side of the third direction D3 that is close to the first shield 30, is more susceptible to magnetic saturation.

[0134] Furthermore, the first shield 30 in this embodiment is formed by stacking 1-1 steel plates 30a to 1-5 steel plates 30e, which are made of electromagnetic steel, in the third direction D3. As a result, the first back surface 32 is formed, and magnetic flux is easily input to the 1-5 steel plate 30e, which is located closest to the second shield 40. Moreover, the anisotropy of each of the 1-1 steel plates 30a to 1-5 steel plates 30e in the first shield 30 is set to the first direction D1, which is perpendicular to the third direction D3. As a result, the magnetic flux input to the 1-5 steel plate 30e is less likely to be guided to the third direction D3, and input to the 1-4 steel plate 30d is suppressed. Consequently, the magnetic flux input to the first shield 30 is even more likely to concentrate on the 1-5 steel plate 30e.

[0135] Furthermore, the second shield 40 in this embodiment is formed by stacking 2-1 steel plates 40a to 2-5 steel plates 40e, which are made of electromagnetic steel, in the third direction D3. As a result, a second back surface 42 is formed, and magnetic flux is easily input to the 2-5 steel plate 40e, which is located closest to the first shield 30. Moreover, the anisotropy of each of the 2-1 steel plates 40a to 2-5 steel plates 40e in the second shield 40 is set to the first direction D1, which is perpendicular to the third direction D3. As a result, magnetic flux input to the 2-5 steel plate 40e is less likely to be guided to the third direction D3, and input to the 2-4 steel plate 40d is suppressed. Consequently, the magnetic flux input to the second shield 40 is even more likely to concentrate on the 2-5 steel plate 40e.

[0136] Furthermore, the second shield 40 has second extensions 46 that extend toward the first shield 30 on both the first direction D1 and the other side. Therefore, when magnetic flux flows through the shield magnetic circuit, the magnetic flux flowing through the second shield 40 is easily guided to the first-fifth steel plate 30e via the second extensions 46. Also, the magnetic flux flowing from the first shield 30 to the second shield 40 is easily guided to the second-fifth steel plate 40e via the second extensions 46. Consequently, magnetic flux is more easily concentrated on the first-fifth steel plate 30e and the second-fifth steel plate 40e compared to a configuration in which the second extensions 46 are not provided.

[0137] As described above, if the current flowing through the conductive busbar 50 increases, there is a risk that the first back surface 32 of the first shield 30 and the second back surface 42 of the second shield 40 will become magnetically saturated. If magnetic flux leaks from the magnetic circuit due to the magnetic saturation of the first back surface 32 and the second back surface 42, this leaked magnetic flux may be input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, potentially worsening the detection accuracy of the current detection device 1.

[0138] In contrast, by forming a recessed portion 321 on the back side of the first shield 30 in this embodiment, leakage of magnetic flux from the magnetic circuit is suppressed, making it difficult for the first shield 30 to become magnetically saturated.

[0139] Here, a comparison of the case in which the first shield 30 has a recessed portion 321 on its back side and the case in which it does not will be explained with reference to Figures 21 to 30. Figure 21 shows a schematic diagram of the current detection device 1 having the first shield 30 of this embodiment, and the magnetic flux flowing through the first shield 30 and the second shield 40 is indicated by arrows. Figure 22 shows a schematic diagram of the comparative current detection device C1 having a comparative first shield C30, which is a comparative example of the first shield 30 of this embodiment, and the magnetic flux flowing through the comparative first shield C30 and the second shield 40 is indicated by arrows. The configuration of the comparative current detection device C1 is the same as that of the current detection device 1, except for the comparative first shield C30. Note that in Figures 21 and 22, in order to make the flow of magnetic flux easier to understand, the dimensions of the first shield 30 and the comparative first shield C30 in the first direction D1 are shown to be shorter, and the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are shown in an exaggerated manner.

[0140] Furthermore, Figures 23, 24, 26, 27, 29, and 30 show the difference in magnetic flux density of the comparative first shield C30 and the first shield 30 when a relatively large current flows through the conductive busbar 50 of the current detection device 1 and the comparative current detection device C1, respectively. Figures 23, 24, and 27 are contour plots showing the magnetic flux density of the comparative first shield C30 and the second shield 40 when the current flowing through the conductive busbar 50 is 1000 amperes or more. Figure 26 is a contour plot showing the magnetic flux density of the comparative first shield C30 and the second shield 40 when the current flowing through the conductive busbar 50 is further increased. Figures 29 and 30 show the magnetic flux density of the first shield 30 and the second shield 40 when the current flowing through the conductive busbar 50 is the same as the conditions under which the contour plots in Figures 23, 24, and 27 were obtained.

[0141] In the current detection device 1, when current flows from one side to the other in the second direction D2 through the conductive busbar 50, magnetic flux flows through the shield magnetic circuit formed by the first shield 30 and the second shield 40, as shown in Figure 21. Specifically, the magnetic flux flows through each of the 1-1 steel plates 30a to 1-5 steel plates 30e forming the first shield 30, from one side to the other in the first direction D1. Also, the magnetic flux input from the first shield 30 to the second shield 40 flows through each of the 2-2 extensions 46b to 2-5 extensions 46e, from one side to the other in the third direction D3. This magnetic flux is then input to the second central part 43 of the second shield 40, and flows through each of the 2-1 central part 43a to 2-5 central part 43e, from the other side to the one side in the first direction D1, and is input to the second extension 46. The magnetic flux input to the second extension section 46 flows through each of the second-2 extension sections 46b to the second-5 extension sections 46e from one side to the other in the third direction D3, and is then input to the first shield 30.

[0142] Similarly, in the comparative current detection device C1, when a current flows from one side to the other in the second direction D2 through the conductive busbar 50, magnetic flux flows through the shield magnetic circuit formed by the comparative first shield C30 and the second shield 40, as shown in Figure 22.

[0143] Here, as shown in Figure 22, the comparative first shield C30 does not have a recessed portion 321 on the back side compared to the first shield 30, and the other configurations are the same. Specifically, in the comparative first shield C30, the dimension in the first direction D1 of the comparative first-fifth steel plate C30e, which corresponds to the first-fifth steel plate 30e of the first shield 30, is equal to the dimension in the first direction D1 of each of the other steel plates constituting the comparative first shield C30. For this reason, the dimension in the first direction D1 of the comparative first-fifth steel plate C30e is larger than the dimension in the first direction D1 of the first-fifth steel plate 30e.

[0144] Furthermore, the separation distance between the first shield C30 and the second extension 46 of the second shield 40 is smaller than the separation distance between the first shield 30 and the second extension 46 of the second shield 40. Here, as shown in Figure 21, the separation distance from one end of the first-fifth steel plate 30e in the first direction D1 to the second extension 46 on the same side of the first direction D1 in the second shield 40 is defined as the first magnetic path length L1. Also, the separation distance from the other end of the first-fifth steel plate 30e in the first direction D1 to the second extension 46 on the other side of the first direction D1 in the second shield 40 is defined as the second magnetic path length L2.

[0145] As shown in Figure 22, the distance from one end of the first direction D1 in the comparative steel plate C30e to the second extension 46 on the same side in the first direction D1 in the second shield 40 is defined as the comparative first magnetic path length CL1. The distance from the other end of the first direction D1 in the comparative steel plate C30e to the second extension 46 on the same side in the first direction D1 in the second shield 40 is defined as the comparative second magnetic path length CL2. The comparative first magnetic path length CL1 is smaller than the first magnetic path length L1. The comparative second magnetic path length CL2 is also smaller than the second magnetic path length L2.

[0146] Thus, since the comparative first magnetic path length CL1 is smaller than the first magnetic path length L1, and the comparative second magnetic path length CL2 is smaller than the second magnetic path length L2, the magnetic resistance between the comparative first shield C30 and the second shield 40 is smaller than the magnetic resistance between the first shield 30 and the second shield 40. Furthermore, the magnetic resistance of the entire shield magnetic circuit formed by the comparative first shield C30 and the second shield 40 is smaller than the magnetic resistance of the entire shield magnetic circuit formed by the first shield 30 and the second shield 40.

[0147] Therefore, in the comparative current detection device C1, where the overall magnetic resistance of the shield magnetic circuit is small, the magnetic flux output from the second shield 40 is more easily input to the comparative first shield C30 compared to the first shield 30. Furthermore, as a result of the magnetic flux being more easily input to the comparative first shield C30, the magnetic flux output from the comparative first shield C30 increases, and thus the magnetic flux input from the comparative first shield C30 to the second shield 40 increases.

[0148] Furthermore, in the comparative first shield C30, which is made up of multiple laminated electromagnetic steel sheets, the magnetic flux from the second shield 40 is more easily input to the comparative first-fifth steel sheet C30e, which is the shortest distance from the second shield 40 compared to the other steel sheets. And, since the magnetic flux input to the comparative first-fifth steel sheet C30e, which has an anisotropy in the first direction D1, is less likely to be guided to the other steel sheets, the magnetic flux tends to concentrate on the comparative first-fifth steel sheet C30e. Therefore, in the comparative first shield C30, the magnetic flux tends to concentrate more easily on the comparative first back surface C32, which corresponds to the first back surface 32 of the first shield 30, compared to the first shield 30. Note that the hatching shown in Figure 22 indicates the areas where the magnetic flux is concentrated.

[0149] Furthermore, in the second shield 40, which is made up of multiple laminated electromagnetic steel sheets, the magnetic flux from the comparative first shield C30 is more easily input to the second-fifth steel sheet 40e, which is the shortest distance from the comparative first shield C30 compared to the second-first steel sheet 40a to the second-fourth steel sheet 40d. And, since the magnetic flux input to the second-fifth steel sheet 40e, which has an anisotropy in the first direction D1, is less likely to be guided to the other steel sheets, the magnetic flux tends to concentrate on the second-fifth steel sheet 40e. Therefore, the magnetic flux tends to concentrate on the second back surface 42 of the second shield 40 compared to the case where the magnetic flux output from the first shield 30 is input. Moreover, the magnetic flux from the output from the comparative first shield C30 is input to the second shield 40, and the magnetic flux also tends to concentrate on the second extension 46, which is the part that guides the output magnetic flux to the comparative first shield C30.

[0150] Therefore, in the comparative current detection device C1, as shown in the hatching in Figures 22 to 24 and Figure 27, magnetic flux tends to concentrate on the first comparative back surface C32 facing the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. In other words, in the first comparative shield C30, magnetic flux tends to concentrate in the central part of the first direction D1 on the first comparative back surface C32. Similarly, in the second shield 40, magnetic flux tends to concentrate in the central part of the first direction D1 on the second back surface 42. Furthermore, in the comparative current detection device C1, magnetic flux tends to concentrate in the part of the second extension 46 that is close to the second back surface 42.

[0151] Then, when the magnetic flux concentrates on the comparison first back surface C32 and the comparison first back surface C32 becomes magnetically saturated, it becomes difficult for the magnetic flux output from the second extension 46 of the second shield 40 to be input to the comparison first shield C30. As a result, the magnetic flux output from the second extension 46 leaks out of the shield magnetic circuit formed by the comparison first shield C30 and the second shield 40. In this case, as shown in Figure 23, this leaked magnetic flux flows toward one side and the other side of the first direction D1 and is input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a as electromagnetic noise.

[0152] When this electromagnetic noise is input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, this electromagnetic noise is superimposed on the magnetic flux of the magnetic field under test, so the magnetic flux detected by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a increases. As a result, the output value of the magnetic detection signal output by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a becomes larger than the output value when the comparison first back surface C32 is not magnetically saturated, as shown in Figure 25. In other words, the output value of the magnetic detection signal becomes larger compared to when only the magnetic flux of the magnetic field under test is input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0153] Furthermore, as the current value flowing through the conductive busbar 50 increases, the magnetic flux density of the first comparison back surface C32 increases, as shown in Figure 26, and consequently, the error in the output value of the magnetic detection signal increases, as shown in Figure 25. The solid line in Figure 25 shows the output value of the magnetic detection signal when the first comparison back surface C32 is not magnetically saturated, while the dashed line in Figure 25 shows the output value of the magnetic detection signal when the first comparison shield C30 is magnetically saturated.

[0154] Therefore, when the current flowing through the conductive busbar 50 is calculated based on the magnetic detection signal with a larger output value, the calculated current value becomes larger compared to the actual current value. In other words, electromagnetic noise leaking from the shield magnetic circuit formed by the first comparison shield C30 and the second shield 40 reduces the detection accuracy of the comparison current detection device C1.

[0155] Furthermore, if the magnetic flux concentrates on the second back surface 42, causing the second back surface 42 to become magnetically saturated, it becomes difficult for the magnetic flux output from the comparative first shield C30 to be input to the second shield 40. As a result, the magnetic flux output from the comparative first shield C30 leaks out of the shield magnetic circuit formed by the comparative first shield C30 and the second shield 40. In this case, as shown in Figure 27, this leaked magnetic flux flows toward the other and one sides of the first direction D1 and is input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a as electromagnetic noise.

[0156] When this electromagnetic noise is input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, this electromagnetic noise cancels out the magnetic flux of the magnetic field under test, thus reducing the magnetic flux detected by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. As a result, the output value of the magnetic detection signal output by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a becomes smaller compared to the output value when the second back surface 42 is not magnetically saturated, as shown in Figure 25. In other words, the output value of the magnetic detection signal becomes smaller compared to when only the magnetic flux of the magnetic field under test is input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0157] Furthermore, as the current value flowing through the conductive busbar 50 increases, the magnetic flux density on the second back surface 42 increases, as shown in Figure 26, and consequently, the error in the output value of the magnetic detection signal increases, as shown in Figure 27. The dashed line in Figure 27 shows the output value of the magnetic detection signal when the second shield 40 is magnetically saturated.

[0158] Therefore, when the current flowing through the conductive busbar 50 is calculated based on the magnetic detection signal with a reduced output value, the calculated current value becomes smaller compared to the actual current value. In other words, electromagnetic noise leaking from the shield magnetic circuit formed by the first comparison shield C30 and the second shield 40 reduces the detection accuracy of the comparison current detection device C1.

[0159] Here, the detection accuracy of the comparison current detection device C1 when the first comparison back surface C32 is magnetically saturated will be explained with reference to the graph shown in Figure 28. As shown by the dashed line in Figure 28, when the current flowing through the conductive busbar 50 becomes a relatively large current value of 1000 amperes or more, the detection error of the current value detected by the comparison current detection device C1 becomes large. Furthermore, this detection error increases as the current value flowing through the conductive busbar 50 increases.

[0160] As explained above, if the current flowing through the conductive busbar 50 increases and at least one of the first shield 30 and the second shield 40 becomes magnetically saturated, there is a risk that the detection accuracy of the current detection device 1 will decrease.

[0161] In contrast, the first shield 30 of this embodiment has a recessed portion 321 formed on the first back surface 32. As a result, the dimension in the first direction D1 of the portion forming the first back surface 32 of the first shield 30 is smaller in the first direction D1 compared to a configuration in which the recessed portion 321 is not formed. Specifically, by forming the recessed portion 321 on the back surface of the first shield 30, the dimension in the first direction D1 of the first-fifth steel plate 30e is smaller compared to a configuration in which the recessed portion 321 is not formed.

[0162] Therefore, since the first magnetic path length L1 is greater than the comparative first magnetic path length CL1, and the second magnetic path length L2 is greater than the comparative second magnetic path length CL2, the magnetic resistance between the first shield 30 and the second shield 40 is greater than the magnetic resistance between the comparative first shield C30 and the second shield 40. Furthermore, the magnetic resistance of the entire shield magnetic circuit formed by the first shield 30 and the second shield 40 is greater than the magnetic resistance of the entire shield magnetic circuit formed by the comparative first shield C30 and the second shield 40.

[0163] Therefore, in the current detection device 1, where the overall magnetic resistance of the shield magnetic circuit is large, the magnetic flux output from the second shield 40 is less likely to be input to the first shield 30 compared to the comparative first shield C30. Specifically, in the first shield 30, which is formed by laminating the first-1 steel plates 30a to the first-5 steel plates 30e, the formation of the recess 321 on the back side reduces the magnetic flux input to the first-5 steel plate 30e, which is located closest to the second shield 40. As a result of the reduced input of magnetic flux to the first shield 30, the magnetic flux output from the first shield 30 decreases, and therefore the magnetic flux input to the second shield 40 decreases.

[0164] Furthermore, because it becomes more difficult for magnetic flux to be input to the first-fifth steel plate 30e, the magnetic flux output from the second shield 40 is guided to the first-first steel plate 30a to the first-fourth steel plate 30d. As a result, the difference between the amount of magnetic flux input to the first-fifth steel plate 30e, which is closest to the second shield 40, and the amount of magnetic flux input to each of the first-first steel plates 30a to the first-fourth steel plates 30d becomes smaller, and the magnetic flux input to the first shield 30 is homogenized.

[0165] Furthermore, the magnetic flux input to each of the 1-1 steel plates 30a to 1-5 steel plates 30e, which have anisotropy in the first direction D1, is less likely to be guided to the other steel plates. As a result, the magnetic flux input to the 1-4 steel plate 30d is suppressed from being guided in the third direction D3 and input to the 1-5 steel plate 30e. Consequently, the first shield 30 is less likely to concentrate magnetic flux on the first back surface 32 compared to the case where the first shield 30 is not composed of 1-1 steel plates 30a to 1-5 steel plates 30e, which have anisotropy in the first direction D1.

[0166] Furthermore, the formation of the recessed portion 321 on the back side of the first shield 30 increases the distance between the first-fifth steel plate 30e and the second-fifth steel plate 40e, thus reducing the magnetic flux input to the second-fifth steel plate 40e, which is positioned closest to the first shield 30. Consequently, the second shield 40 receives less magnetic flux from the first shield 30 compared to a configuration in which the recessed portion 321 on the back side of the first shield 30 is not formed. Moreover, the second shield 40 receives less magnetic flux from the first shield 30 to the second extension portion 46, which is the part to which the magnetic flux output from the first shield 30 is input, and also receives less magnetic flux from the second extension portion 46, which guides the magnetic flux to the first shield 30.

[0167] Therefore, in the current detection device 1, as shown in the hatching in Figure 29, magnetic flux is less likely to concentrate on the first back surface 32 facing the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. In other words, the first shield 30 is less likely to concentrate magnetic flux in the central part of the first direction D1 on the first back surface 32.

[0168] As a result, magnetic flux is less likely to concentrate on the first back surface 32, thus suppressing magnetic saturation of the first back surface 32. Therefore, the magnetic flux output from the second extension 46 is less likely to leak from the shield magnetic circuit formed by the first shield 30 and the second shield 40. Consequently, as shown in Figure 29, the magnetic flux output from the second extension 46 is suppressed from being input as electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0169] Furthermore, in the current detection device 1, as shown by the hatching in Figure 30, magnetic flux is less likely to concentrate on the second back surface 42 facing the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. In other words, the second shield 40 is less likely to concentrate magnetic flux in the central part of the second back surface 42 in the first direction D1.

[0170] As a result, magnetic flux is less likely to concentrate on the second back surface 42, thus suppressing magnetic saturation of the second back surface 42. Therefore, the magnetic flux output from the first shield 30 is less likely to leak from the shield magnetic circuit formed by the first shield 30 and the second shield 40. Consequently, as shown in Figure 30, the magnetic flux output from the first shield 30 is suppressed from being input as electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0171] Furthermore, in the current detection device 1, magnetic flux is less likely to concentrate in the portion of the second extension 46 that is close to the second back surface 42.

[0172] This suppresses the influence of electromagnetic noise leaking from the shield magnetic circuit when the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a detect the magnetic flux of the magnetic field under measurement. Therefore, errors in the magnetic detection signals output by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are suppressed, and the detection accuracy of the current value of the current flowing through the conductive busbar 50, which is calculated based on the magnetic detection signal, can be improved. In this way, by suppressing magnetic saturation of the first shield 30 and the second shield 40, the detection accuracy of the current detection device 1 can be improved even when the current flowing through the conductive busbar 50 increases.

[0173] Here, the detection accuracy of the current detection device 1 of this embodiment will be explained with reference to the graph shown in Figure 28. As shown by the solid line in Figure 28, even when the current flowing through the conductive busbar 50 is a relatively large current value of 1000 amperes or more, the detection error of the current value detected by the current detection device 1 can be reduced compared to the comparative current detection device C1. Furthermore, even in the range where the detection error of the current value detected by the comparative current detection device C1 increases as the current value of the conductive busbar 50 increases, the detection error of the current detection device 1 was significantly reduced compared to such an error. Thus, the current detection device 1 of this embodiment, which has a first shield 30 with a recessed portion 321 formed on the back side, can suppress the detection error even when the current value of the current flowing through the conductive busbar 50 is large.

[0174] As described above, the current detection device 1 of this embodiment includes a conductive busbar 50 through which current flows in a second direction D2, and a first sensing unit 23 and a second sensing unit 24 that convert the magnetic field to be measured, generated by the flow of current through the conductive busbar 50, into a magnetic detection signal. Furthermore, the current detection device 1 includes a shielding unit that suppresses the input of electromagnetic noise to the first sensing unit 23 and the second sensing unit 24. The shielding unit has a plate-shaped first shield 30 and a second shield 40 that are spaced apart from each other and facing a third direction D3, and include portions that extend in the first direction D1 and the second direction D2, respectively. A portion of the conductive busbar 50 is positioned between the first shield 30 and the second shield 40. The first sensing unit 23 and the second sensing unit 24 are each positioned between the first shield 30 and the second shield 40 and have a magnetic detection element that detects a magnetic field passing through them. The first shield 30 has a first back surface 32 that faces the second shield 40. The second shield 40 has a second back surface 42 facing the first shield 30. The first back surface 32 has a back surface recess 321 formed in a recess in the third direction D3. The back surface recess 321 is formed in a position that does not overlap with the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, which each have a magnetic detection element, in the third direction D3.

[0175] According to this, compared to a configuration in which the first back surface 32 does not have a recessed portion 321 on the back surface side, the magnetic flux output from the second shield 40 is less likely to penetrate the area forming the first back surface 32. As a result, the first back surface 32 of the first shield 30 is less likely to become magnetically saturated due to the concentration of magnetic flux.

[0176] Therefore, the magnetic saturation of the first shield 30 prevents interference with the input of magnetic flux from the second shield 40 to the first shield 30. Furthermore, it is possible to prevent the magnetic flux output from the second shield 40 from being input as electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0177] Furthermore, as the magnetic flux output from the second shield 40 becomes less likely to penetrate the first shield 30, the magnetic flux input from the second shield 40 to the first shield 30 decreases, and as a result, the magnetic flux input from the first shield 30 to the second shield 40 decreases. Therefore, the second shield 40 becomes less likely to become magnetically saturated by the magnetic flux input from the first shield 30 to the second shield 40.

[0178] Therefore, the magnetic saturation of the second shield 40 prevents interference with the input of magnetic flux from the first shield 30 to the second shield 40. This also prevents the magnetic flux output from the first shield 30 from being input as electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0179] Thus, the configuration having the recessed portion 321 on the back side makes it possible to suppress electromagnetic noise leaking from the shield magnetic circuit formed by the first shield 30 and the second shield 40 from being input to the first sensing unit 23 and the second sensing unit 24. Therefore, even if a relatively large current flows through the conductive busbar 50, it is possible to suppress the deterioration of the detection accuracy of the current detection device 1 caused by magnetic flux leakage from the shield magnetic circuit and improve the detection accuracy of the current detection device 1.

[0180] By the way, by forming a recessed portion 321 on the back side of the first shield 30, the thickness of the first shield 30 in the third direction D3 in the area where the recessed portion 321 is formed becomes smaller. As a result, the shielding performance of the first shield 30 against external noise in the area where the recessed portion 321 is formed decreases, and there is a risk that the input of external noise will not be sufficiently suppressed. Therefore, if the recessed portion 321 on the back side is formed in a position that overlaps with the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a in the third direction D3, there is a risk that external noise will be input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0181] In contrast, the recessed portion 321 on the back side of this embodiment is formed in a position that does not overlap with the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a in the third direction D3. As a result, even if the shielding performance of the first shield 30 is reduced by forming the recessed portion 321 on the back side of the first shield 30, it is possible to suppress the input of external noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0182] Furthermore, according to the above embodiment, the following effects can be obtained.

[0183] (1) In the above embodiment, the first shield 30 on which the back side recess 321 is formed is formed by stacking first-1 steel plates 30a to first-5 steel plates 30e, whose magnetic permeability anisotropy is in the first direction D1, in the third direction D3. The back side recess 321 is formed in the first-5 steel plate 30e, which forms the first back surface 32, among the first-1 steel plates 30a to first-5 steel plates 30e.

[0184] According to this, it becomes difficult for a magnetic field to penetrate the first-fifth steel plates 30e that form the first back surface 32, and the concentration of magnetic flux on the first back surface 32 can be avoided. Furthermore, since the anisotropy of each of the first-first steel plates 30a to the first-fifth steel plates 30e is set to a first direction D1 that is perpendicular to the third direction D3, the magnetic flux input to each of the first-first steel plates 30a to the first-fifth steel plates 30e is less likely to be guided to the third direction D3. As a result, the magnetic flux input to the first-fourth steel plate 30d is less likely to be guided to the third direction D3 and input to the first-fifth steel plate 30e, and furthermore, the concentration of magnetic flux on the first back surface 32 becomes less likely.

[0185] Therefore, even when a relatively large current flows through the conductive busbar 50, the first shield 30 makes it even more difficult for the first back surface 32 to become magnetically saturated, further improving the detection accuracy of the current detection device 1.

[0186] (2) In the above embodiment, the second shield 40 has a second extension 46 extending toward the first shield 30 at one end and the other end in the second direction D2.

[0187] As a result, the separation distance in the third direction D3 between the first central portion 34 of the first shield 30 and the second extension portion 46 of the second shield 40 becomes shorter than the separation distance in the third direction D3 between the first back surface 32 of the first shield 30 and the second back surface 42 of the second shield 40. Therefore, magnetic flux that enters the first shield 30 can easily pass through to the second shield 40 via the second extension portion 46. Similarly, magnetic flux that enters the second shield 40 can easily pass through to the first shield 30 via the second extension portion 46.

[0188] Therefore, compared to a configuration in which the second shield 40 does not have the second extension portion 46, magnetic flux is less likely to concentrate on the first back surface 32, and the occurrence of magnetic saturation on the first back surface 32 can be further suppressed. As a result, the detection accuracy of the current detection device 1 can be further improved.

[0189] (3) In the above embodiment, the recessed portion 321 on the back surface is formed at one end and the other end of the first back surface 32 in the first direction D1.

[0190] This configuration allows for a larger separation distance from both ends of the first back surface 32 in the first direction D1 to the second extension 46 of the second shield 40 compared to a configuration where the recess 321 on the back surface is formed only at one end of the first back surface 32 in the first direction D1. As a result, the magnetic resistance of the shield magnetic circuit formed by the first shield 30 and the second shield 40 can be increased, further suppressing the occurrence of magnetic saturation of the first back surface 32. Therefore, the detection accuracy of the current detection device 1 can be further improved.

[0191] (4) In the above embodiment, the recessed portion 321 on the back surface is formed by cutting out from one end to the other end in the second direction D2 on the first back surface 32.

[0192] According to this, the magnetic resistance of the shield magnetic circuit can be increased compared to the case where the recessed portion 321 on the back side is not formed in this manner. As a result, the occurrence of magnetic saturation on the first back surface 32 can be further suppressed, and the detection accuracy of the current detection device 1 can be further improved.

[0193] (5) In the above embodiment, the dimension of the first central portion 34 in the second direction D2 of the first shield 30 in the first direction D1 is greater than the dimension of the first end portions 35, which are the ends of the first shield 30 in the second direction D2.

[0194] According to this, the permeability of the first end portion 35 in the first direction D1 is lower than that of the first central portion 34, making it difficult for a magnetic field to penetrate the first end portion 35. Therefore, it becomes difficult for a magnetic field to pass through the first central portion 34 from one first end portion 35 to the other first end portion 35, making it difficult for the first central portion 34 to become magnetically saturated.

[0195] (5) In the above embodiment, the plate-shaped first shield 30 is formed by cutting out the four corners.

[0196] According to this, a first shield 30 can be easily realized in which the dimension of the first central portion 34 in the first direction D1 is larger than the dimension of the first end portion 35 in the first direction D1.

[0197] (6) In the above embodiment, the dimension of the second central portion 43 in the second direction D2 of the second shield 40 in the first direction D1 is greater than the dimension of the second end portions 44, which are the ends of the second shield 40 in the second direction D2, in the first direction D1.

[0198] According to this, the permeability in the first direction D1 is lower at the second end portion 44 than at the second central portion 43, making it difficult for the magnetic field to penetrate the second end portion 44. Therefore, it becomes difficult for the magnetic field to pass from one second end portion 44 to the other second end portion 44 via the second central portion 43, making it difficult for the second central portion 43 to become magnetically saturated.

[0199] (First Modification of the First Embodiment) In the first embodiment described above, an example was described in which one recessed portion 321 on the back surface side is formed at one end and the other end in the first direction D1 on the first back surface 32, but the invention is not limited thereto.

[0200] The recessed portion 321 on the back surface may be formed in a location different from one end and the other end of the first direction D1 on the first back surface 32, as long as it does not overlap with the first magnetoelectric conversion portion 231a and the second magnetoelectric conversion portion 241a in the third direction D3. In this case, for example, as shown in Figure 31, the recessed portion 321 on the back surface 32 may be formed on the side of one end of the first direction D1 on the first back surface 32, and on the side of the other end of the first direction D1 on the first back surface 32.

[0201] Thus, even when the recessed portion 321 on the back surface 32 is formed at a location different from the end in the first direction D1, magnetic flux is less likely to be input to the first-fifth steel plate 30e compared to a configuration in which the recessed portion 321 on the back surface 321 is not formed. Therefore, because magnetic flux is less likely to be input to the first-fifth steel plate 30e, the magnetic flux output from the second shield 40 is guided to the first-first steel plate 30a to the first-fourth steel plate 30d, and magnetic flux is less likely to concentrate on the first back surface 32. As a result, the difference between the amount of magnetic flux input to the first-fifth steel plate 30e, which is closest to the second shield 40, and the amount of magnetic flux input to each of the first-first steel plate 30a to the first-fourth steel plate 30d becomes smaller, and as shown in Figure 32, the magnetic flux input to the first shield 30 is homogenized.

[0202] Furthermore, the magnetic flux input to each of the 1-1 steel plates 30a to 1-5 steel plates 30e, which have anisotropy in the first direction D1, is less likely to be guided to the other steel plates. As a result, the magnetic flux input to the 1-4 steel plate 30d is suppressed from being guided in the third direction D3 and input to the 1-5 steel plate 30e. Consequently, the first shield 30 is less likely to concentrate magnetic flux on the first back surface 32 compared to the case where the first shield 30 is not composed of 1-1 steel plates 30a to 1-5 steel plates 30e, which have anisotropy in the first direction D1.

[0203] As a result, magnetic saturation of the first back surface 32 is suppressed, and the magnetic flux output from the second extension 46 is suppressed from being input as electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. Therefore, even when the current flowing through the conductive busbar 50 increases, the detection accuracy of the current detection device 1 can be improved.

[0204] (Second Modification of the First Embodiment) In the first embodiment described above, an example was described in which the recessed portion 321 on the back surface side is formed by cutting out from one end to the other end in the second direction D2 on the first back surface 32, but the invention is not limited thereto.

[0205] The recessed portion 321 on the back side may have a shape in which the size in the second direction D2 is smaller than the size in the second direction D2 of the first shield 30. In this case, for example, as shown in Figure 33, the recessed portion 321 on the back side may be formed extending from the other end of the second direction D2 on the first back surface 32 toward the other end toward the middle of the first back surface 32. Alternatively, as shown in Figure 34, the recessed portion 321 on the back side may be formed in the center of the second direction D2 on the first back surface 32.

[0206] (Third Modification of the First Embodiment) In the first embodiment described above, an example was described in which the first shield 30 and the second shield 40 are manufactured by bonding together a plurality of flat plate members made of a soft magnetic material, but the invention is not limited thereto.

[0207] For example, the first shield 30 and the second shield 40 may be manufactured by pressing together a plurality of flat plate members made of a soft magnetic material. In this case, for example, as shown in Figure 35, the first shield 30 has six protrusions (not shown) that project from the first surface 31 and six recesses 38 that are recessed from the first back surface 32 toward the first surface 31 on each of the first-1 steel plates 30a to the first-5 steel plates 30e. The first-1 steel plates 30a to the first-5 steel plates 30e are arranged so that their respective first surface 31 and first back surface 32 face each other. The first shield 30 may be manufactured by fitting the protrusion of one of the two opposing steel plates in the first-1 steel plates 30a to the first-5 steel plates 30e into the recess 38 of the other steel plate and stacking them, and then pressing together the first-1 steel plates 30a to the first-5 steel plates 30e in a stacked state. Furthermore, the second shield 40 may be constructed in the same manner as the first shield 30.

[0208] In this case, the thickness of the first shield 30 and the second shield 40 increases in the area where the recess 38 and the protrusion are fitted together. Also, the recess 321 on the back side can be formed in an area other than the area where the recess 38 and the protrusion are fitted together.

[0209] (Fourth Modification of the First Embodiment) In the first embodiment described above, an example was described in which the back surface recess 321 is formed only on the first back surface 32 side of the first shield 30, but the invention is not limited thereto.

[0210] For example, as shown in Figure 36, the first shield 30 may also have a surface-side recess 311 on the first surface 31 side that corresponds to the back-side recess 321. In this case, the surface-side recess 311 is formed by being recessed from the first surface 31 toward the other side in the third direction D3, and may have the same configuration as the back-side recess 321.

[0211] Specifically, the surface-side recesses 311 are formed in a position that does not overlap with the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, which have magnetic detection elements, in the third direction D3. Furthermore, one surface-side recess 311 is formed at each end of the first surface 31 in the first direction D1. The two surface-side recesses 311 are formed at each end of the first surface 31 in the first direction D1, extending from one end to the other end in the second direction D2. The space formed by the surface-side recesses 311 forms a rectangular parallelepiped with the second direction D2 as its extension direction.

[0212] As shown in Figure 37, the surface recess 311 is formed in the first shield 30 by reducing the size of the first direction D1 of the first-first steel plate 30a. As a result, the size of the first direction D1 of the first-first steel plate 30a is smaller than that of the first direction D1 of the first-second steel plates 30b to the first-fourth steel plates 30d. In addition, the size of the first direction D1 of the first-first steel plate 30a is equal to that of the first direction D1 of the first-fifth steel plate 30e.

[0213] The surface recess 311 formed in this manner is formed on the surface of the first shield 30 opposite to the surface on which the back recess 321 is formed. In other words, the surface recess 311 is realized by the first steel plate 30a, which is on the opposite side of the first steel plate 30e from the first steel plate 30a to the first steel plate 30e. Furthermore, the first steel plate 30a has the same shape as the first steel plate 30e.

[0214] Therefore, in the first shield 30, where the 1-1 steel plate 30a is positioned on one side of the third direction D3 and the 1-5 steel plate 30e is positioned on the other side of the third direction D3, the shape of the first surface 31 side and the shape of the first back surface 32 side are equal to each other. Furthermore, the first shield 30 is symmetrical with respect to a virtual line passing through the center of the third direction D3 and along the first direction D1. Consequently, when attaching the first shield 30 to the sensor housing 10, the first shield 30 can be attached even if the first surface 31 side and the first back surface 32 side are reversed, improving ease of assembly.

[0215] (Fifth Modification of the First Embodiment) In the first embodiment described above, an example was described in which one recess 321 on the back surface is formed at one end and the other end of the first direction D1 on the first back surface 32, but the invention is not limited thereto.

[0216] For example, the recessed portion 321 on the back surface may be formed only on one side of the first direction D1 from the center of the first direction D1 on the first back surface 32, or on the other side. Alternatively, multiple recessed portions 321 on the back surface may be formed on either one side of the first direction D1 from the center of the first direction D1 on the first back surface 32, or multiple recessed portions may be formed on both the one side and the other side of the first direction D1.

[0217] (Sixth Modification of the First Embodiment) In the first embodiment described above, an example was described in which the first-fifth steel plate 30e is notched to form a recessed portion 321 on the back side, but the invention is not limited thereto.

[0218] For example, the recessed portion 321 on the back side may not penetrate the third direction D3 of the first-fifth steel plate 30e, but rather be formed by recessing the other side of the first-fifth steel plate 30e in the third direction D3. Also, the recessed portion 321 on the back side may be formed not only by cutting out the first-fifth steel plate 30e, but also by cutting out other steel plates. For example, the recessed portion 321 on the back side may be formed by cutting out portions of the first-fifth steel plate 30e and the first-fourth steel plate 30d that overlap in the third direction D3 of each, and these cut-out portions.

[0219] (Seventh Modification of the First Embodiment) In the first embodiment described above, a recessed portion 321 is formed on the first back surface 32 of the flat plate-shaped first shield 30, and the magnetic saturation of the first back surface 32 and the second back surface 42 is suppressed by the recessed portion 321. However, the invention is not limited to this.

[0220] For example, the second shield 40 may be configured to have a recess corresponding to the back-side recess 321 formed on the second back surface 42. Even if a recess corresponding to the back-side recess 321 is formed on the second back surface 42 of the second shield 40, magnetic saturation of the first back surface 32 and the second back surface 42 can be suppressed. In this case, the second shield 40 may be formed in a flat plate shape extending in the first direction D1 and the second direction D2, similar to the first shield 30, and may not have the second extension 46.

[0221] (Second Embodiment) Next, a second embodiment will be described with reference to Figures 38 to 40. In this embodiment, the shapes of the first shield 30 and the second shield 40 differ from those of the first embodiment. Other than this, it is the same as the first embodiment. For this reason, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0222] As shown in Figure 38, the first shield 30 of this embodiment does not have a recessed portion 321 formed on the back surface 32. That is, in the first shield 30 of this embodiment, the dimensions in the first direction D1 of each of the 1-1 steel plate 30a to 1-5 steel plate 30e are equal to each other.

[0223] Furthermore, in this embodiment, the second shield 40 has an extended recess 461 formed in the second extended portion 46. The extended recess 461 is formed in the second extended portion 46 provided on one side and the other side of the second shield 40 in the first direction D1. The extended recess 461 formed in the second extended portion 46 on one side in the first direction D1 is formed with the end of the second extended portion 46 on the other side in the first direction D1 recessed toward the other side in the third direction D3. That is, the inside of the second extended portion 46 on one side in the first direction D1 is provided with an extended recess 461 that is formed recessed toward the other side in the third direction D3.

[0224] The extended recess 461 formed in the second extended portion 46 on the other side of the first direction D1 is formed with one end of the second extended portion 46 in the first direction D1 recessed toward the other side of the third direction D3. That is, an extended recess 461 is provided on the inside of the second extended portion 46 on the other side of the first direction D1, recessed toward the other side of the third direction D3. These two extended recesses 461 are formed by cutting out from one end to the other end of the second extended portion 46 in the second direction D2. The space formed by the extended recess 461 forms a rectangular parallelepiped with the second direction D2 as the extension direction.

[0225] Here, the second shield 40 is formed by laminating the second-first steel plates 40a to the second-fifth steel plates 40e, which are made of a soft magnetic material, as described above. The second extension portion 46 is formed by bending the portions of each of the second-second steel plates 40b to the second-fifth steel plates 40e that protrude from one side and the other side in the first direction D1 toward one side in the third direction D3. As a result, the two second extension portions 46 are formed with the second-second extension portion 46b to the second-fifth extension portion 46e overlapping in the first direction D1.

[0226] However, in this embodiment, the second-fifth extension 46e is formed such that the position of one end of the second extension 46b to the second-fourth extension 46d does not overlap with the position of one end of the second extension 46b to the second-fourth extension 46d in the third direction D3. Specifically, as shown in Figure 39, the portion of the second-fifth extension 46e at one end in the third direction D3 is positioned on the other side of the third direction D3 from the portion of the second extension 46b to the second-fourth extension 46d in the third direction D3.

[0227] In other words, of the second-second extensions 46b to the second-fifth extensions 46e, the second-fifth extension 46e, which is the innermost, is recessed to the other side of the third direction D3 compared to the second-second extensions 46b to the second-fourth extensions 46d. By positioning the second-fifth extension 46e to the other side of the third direction D3 in this way, an extension recess 461 is formed in the second shield 40.

[0228] The extended recess 461 is realized by the 2-5 steel plate 40e, which is closest to the 1-5 steel plate 30e, among the 2-1 steel plate 40a to 2-5 steel plate 40e that are laminated. Specifically, the extended recess 461 is formed by cutting out the 2-5 extended portion 46e, which is closest to the first shield 30, among the 2-2 extended portion 46b to 2-5 extended portion 46e that form the second extended portion 46 that extends toward the first shield 30. In other words, the extended recess 461 formed in each of the two second extended portions 46 of this embodiment is formed by cutting out one end in the third direction D3 of the innermost 2-5 extended portion 46e, among the 2-2 extended portion 46b to 2-5 extended portion 46e.

[0229] The second shield 40 formed in this manner is separated from the first shield 30 by a greater distance compared to the case where the extended recess 461 is not formed. Specifically, the second extended portion 46 formed on one side of the second shield 40 in the first direction D1 is separated from one end of the second-fifth steel plate 40e in the third direction D3 by a greater distance between it and one end of the first shield 30 in the first direction D1. Similarly, the second extended portion 46 formed on the other side of the second shield 40 in the first direction D1 is separated from one end of the second-fifth steel plate 40e in the third direction D3 by a greater distance between it and the other end of the first shield 30 in the first direction D1.

[0230] Thus, the distance between the second-fifth steel plate 40e and the first shield 30 is greater compared to a configuration in which the extended recess 461 is not formed. As a result, the magnetic resistance between the first shield 30 and the second shield 40 is greater than the magnetic resistance between the first shield 30 and the second shield 40 compared to a configuration in which the extended recess 461 is not formed on the second extended portion 46. Consequently, the magnetic resistance of the entire shield magnetic circuit formed by the first shield 30 and the second shield 40 is increased.

[0231] Therefore, in the current detection device 1, where the magnetic resistance of the entire shield magnetic circuit is large, the magnetic flux output from the first shield 30 becomes less likely to be input to the second shield 40. Specifically, in the second shield 40, which is formed by stacking the second-first steel plates 40a to the second-fifth steel plates 40e, the formation of the extended recess 461 reduces the magnetic flux input to the second-fifth steel plate 40e, which is located closest to the first shield 30. As a result of the reduced input of magnetic flux to the second shield 40, the magnetic flux output from the second shield 40 decreases, and therefore the magnetic flux input to the first shield 30 decreases.

[0232] Furthermore, because it becomes more difficult for magnetic flux to be input to the second-fifth steel plate 40e, the magnetic flux output from the first shield 30 is guided to the second-second steel plate 40b to the second-fourth steel plate 40d. As a result, the difference between the amount of magnetic flux input to the second-fifth steel plate 40e, which is closest to the first shield 30, and the amount of magnetic flux input to each of the second-second steel plate 40b to the second-fourth steel plate 40d becomes smaller, and the magnetic flux input to the second shield 40 is homogenized.

[0233] Furthermore, the magnetic flux input to each of the 2-1 steel plates 40a to 2-5 steel plates 40e, which have anisotropy in the first direction D1, is less likely to be guided to the other steel plates. As a result, the magnetic flux input to the 2-4 steel plate 40d is suppressed from being guided in the third direction D3 and input to the 2-5 steel plate 40e. Consequently, the second shield 40 is less likely to concentrate magnetic flux on the second back surface 42 compared to the case where the second shield 40 is not composed of 2-1 steel plates 40a to 2-5 steel plates 40e, which have anisotropy in the first direction D1. Moreover, the second shield 40 reduces the magnetic flux input from the first shield 30 to the second extension 46, which is the part to which the magnetic flux output from the first shield 30 is input, and also reduces the magnetic flux input to the second extension 46 that guides the magnetic flux to the first shield 30.

[0234] Furthermore, the formation of the extended recess 461 in the second shield 40 increases the distance between the second-fifth steel plate 40e and the first-fifth steel plate 30e, thus reducing the magnetic flux input to the first-fifth steel plate 30e, which is positioned closest to the second shield 40. Consequently, the magnetic flux input from the second shield 40 to the first shield 30 is reduced compared to a configuration in which the extended recess 461 is not formed in the second shield 40.

[0235] Therefore, in the current detection device 1, as shown in the hatching in Figure 40, magnetic flux is less likely to concentrate on the second back surface 42 facing the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. In other words, the second shield 40 is less likely to concentrate magnetic flux in the central part of the second back surface 42 in the first direction D1. Furthermore, in the current detection device 1, magnetic flux is less likely to concentrate in the part of the second extension 46 that is close to the second back surface 42. Moreover, the first shield 30 is less likely to concentrate magnetic flux in the central part of the first back surface 32 in the first direction D1.

[0236] As a result, magnetic flux is less likely to concentrate on the second back surface 42, thus suppressing magnetic saturation of the second back surface 42. Therefore, it is possible to avoid the magnetic flux output from the first shield 30 being difficult to input to the second shield 40, and leakage of magnetic flux from the shield magnetic circuit can be suppressed. Consequently, the magnetic flux output from the first shield 30 is suppressed from being input as electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0237] Furthermore, since magnetic flux is less likely to concentrate on the first back surface 32, magnetic saturation of the first back surface 32 is suppressed. As a result, it is possible to avoid the magnetic flux output from the second shield 40 being difficult to input to the first shield 30, and leakage of magnetic flux from the shield magnetic circuit can be suppressed. Consequently, the magnetic flux output from the second shield 40 is suppressed from being input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a as electromagnetic noise.

[0238] This suppresses the influence of electromagnetic noise leaking from the shield magnetic circuit when the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a detect the magnetic flux of the magnetic field under measurement. Therefore, errors in the magnetic detection signals output by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are suppressed, and the detection accuracy of the current value of the current flowing through the conductive busbar 50, which is calculated based on the magnetic detection signal, can be improved. In this way, by providing the extended recess 461 to suppress magnetic saturation of the first shield 30 and the second shield 40, the detection accuracy of the current detection device 1 can be improved even when the current flowing through the conductive busbar 50 increases.

[0239] (First Modification of the Second Embodiment) In the above-described embodiment, an example was given in which the second-fifth extension portion 46e is notched to form an extension recess portion 461, but the invention is not limited thereto.

[0240] The extended recess 461 may be formed not only by cutting out the second-fifth extended portion 46e, but also by cutting out other steel plates. In this case, as shown in Figure 41, the extended recess 461 may be formed by cutting out the second-third extended portion 46c to the second-fifth extended portion 46e. When forming the extended recess 461 by cutting out the second-third extended portion 46c to the second-fifth extended portion 46e, the amount of cutting out for each of the second-third extended portion 46c to the second-fifth extended portion 46e may be different.

[0241] For example, the closer the second shield 40 is to the first shield 30, the easier it is for the magnetic flux output from the first shield 30 to be input to it. For this reason, the second-fifth steel plate 40e to the second-third steel plate 40c are easier to input to the magnetic flux output from the first shield 30 in this order. For this reason, as shown in Figure 41, the amount of notching may be increased so that the second-fifth extension portion 46e to the second-third extension portion 46c are further away from the first shield 30 in this order. That is, the second-fifth extension portion 46e to the second-third extension portion 46c may be formed so that the position of one end of each of them in the third direction D3 is directed toward one side of the third direction D3 in this order.

[0242] By forming the second-fifth steel plates 40e to the second-third steel plates 40c in this manner, the height of the second extension portion 46 in the third direction D3 can be increased in stages as it moves away from the conductive busbar 50. In other words, the size of the extension recess portion 461 in the third direction D3 gradually decreases from the inside to the outside.

[0243] Thus, even when the extended recess 461 is formed by cutting out a steel plate other than the second-fifth steel plate 40e, the magnetic resistance between the first shield 30 and the second shield 40 can be increased compared to a configuration in which the extended recess 461 is not formed in the second extended portion 46. Therefore, it is possible to make it difficult for the magnetic flux output from the first shield 30 to be input to the second shield 40, and to make it difficult for the magnetic flux output from the second shield 40 to be input to the first shield 30.

[0244] Therefore, as shown in Figure 42, magnetic flux is less likely to concentrate on the second back surface 42, making it less likely for the second back surface 42 to become magnetically saturated, and magnetic flux is less likely to concentrate on the first back surface 32, making it less likely for the first back surface 32 to become magnetically saturated. As a result, the magnetic flux leaking from the shield magnetic circuit is suppressed from being input as electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. This suppresses errors in the magnetic detection signals output by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a, and improves the detection accuracy of the current value of the current flowing through the conductive busbar 50, which is calculated based on the magnetic detection signal.

[0245] (Second Modification of the Second Embodiment) In the second embodiment described above, an example was described in which the back-side recess 321 described in the first embodiment is not formed on the first shield 30, but the invention is not limited thereto.

[0246] As shown in Figure 43, the first shield 30 may have a back-side recess 321 formed on the first back surface 32, similar to the first embodiment.

[0247] (Third Modification of the Second Embodiment) In the second embodiment described above, an example was described in which the extended recess 461 is formed in the second extended portion 46 provided on one side and the other side of the second shield 40 in the first direction D1, respectively, but the invention is not limited thereto.

[0248] The extended recess 461 may be formed on only one of the second extended portions 46, which are provided on one side and the other side of the second shield 40 in the first direction D1.

[0249] (Fourth Modification of the Second Embodiment) In the second embodiment described above, an example was described in which the extended recess 461 is formed by cutting out from one end to the other end in the second direction D2 of the second extended portion 46, but the invention is not limited thereto.

[0250] The extended recess 461 may have a shape in which the size in the second direction D2 is smaller than the size in the second direction D2 of the second extended portion 46. In this case, for example, the extended recess 461 may be formed extending from the other end of the second direction D2 in the second extended portion 46 toward the other end, up to the middle of the second extended portion 46. Alternatively, the extended recess 461 may be formed in the center of the second direction D2 in the second extended portion 46.

[0251] (Fifth Modification of the Second Embodiment) In the second embodiment described above, an example was described in which the second-fifth extension portion 46e is cut out to form an extension recess portion 461, but the invention is not limited thereto.

[0252] For example, the extended recess 461 may not penetrate the second-fifth extended portion 46e in the first direction D1, and the second-fifth extended portion 46e may be formed by being recessed in the first direction D1.

[0253] (Sixth Modification of the Second Embodiment) In the second embodiment described above, an example was described in which an extension recess 461 is provided on the inside of the second extension 46, recessed toward the other side in the third direction D3. Specifically, an example was described in which the extension recess 461 formed in the second extension 46 is formed by cutting off one end in the third direction D3 of the innermost 2-5 extension 46e among the 2-2 extension 46b to 2-5 extension 46e. However, the configuration of the second extension 46 is not limited to this.

[0254] For example, the extended recess 461 may be formed by recessing the outer side of the second extended portion 46 toward the other side of the third direction D3, or by recessing the central portion of the second extended portion 46 in the first direction D1 toward the other side of the third direction D3. In this case, the extended recess 461 may be formed by cutting off one end of the outermost 2-2 extended portion 46b of the 2-2 extended portion 46b to the 2-5 extended portion 46e toward the outermost 2-2 extended portion 46b toward 2-3 extended portion 46c or the 2-4 extended portion 46d toward the 2-5 extended portion 46e toward the outermost 2-2 extended portion 46b toward the 2-5 extended portion 46e toward the outermost 2-3 extended portion 46c or the 2-4 extended portion 46d toward the outermost 2-3 extended portion 46b toward the 2-5 extended portion 46e toward the outermost 2-3 extended portion 46c or the 2-4 extended portion 46d toward the outermost 2-2 extended portion 46b toward the 2-5 extended portion 46e.

[0255] (Perspectives of this Disclosure) As will be apparent from the description of the embodiments above, the disclosures herein include at least the following perspectives:

[0256] [Perspective 1-1] A current detection device comprising: a conductive member (50) having a flat plate shape with one direction of extension as the extension direction through which current flows; magnetic detection units (23, 24) that convert the magnetic field to be measured generated by the flow of the current through the conductive member into a magnetic detection signal; and shielding units (30, 40) that suppress the input of electromagnetic noise to the magnetic detection unit, wherein the shielding units have a plate-shaped first shield (30) and a second shield (40) that are spaced apart from each other and facing each other in predetermined opposing directions, and include portions that extend in the extension direction and in a width direction intersecting the extension direction, respectively; a portion of the conductive member is disposed between the first shield and the second shield; the magnetic detection unit is disposed between the first shield and the second shield and detects the magnetic field that passes through it; and at least one of the first shield and the second shield has an extended portion (46) that extends from one shield to the other shield at at least one of the ends on one side in the extension direction and the other side in the extension direction. A current detection device having a recessed portion (461) formed in the extended portion in the opposite direction.

[0257] [Perspective 1-2] The current detection device according to Perspective 1-1, wherein the recess is formed on the inside of the extension.

[0258] [Perspective 1-3] The current detection device according to Perspective 1-2, wherein, of the first shield and the second shield, the shield in which the recess is formed is formed by stacking a plurality of flat plate members (30a, 30b, 30c, 30d, 30e, 40a, 40b, 40c, 40d, 40e) in the opposing direction, the anisotropy of the magnetic permeability being in the width direction, the extended portion is formed by bending the first shield and the second shield, and the recess is formed by cutting out at least the innermost flat plate member among the plurality of stacked flat plate members.

[0259] [Perspective 1-4] The current detection device according to Perspective 1-1 or Perspective 1-3, wherein the size of the recessed portion gradually decreases in the opposing direction from the inside to the outside of the extended portion.

[0260] [Viewpoint 1-5] The current detection device according to any one of views 1-1 to 1-4, wherein the extended portion is provided at one end in the extension direction and the other end in the extension direction, and the recessed portion is formed in the extended portion provided at one end in the extension direction and the other end in the extension direction.

[0261] (Third Embodiment) Next, a third embodiment will be described with reference to Figures 44 to 46. In this embodiment, the shapes of the first shield 30 and the second shield 40 differ from those of the first embodiment. Other than this, it is the same as the first embodiment. For this reason, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0262] As shown in Figure 44, the first shield 30 of this embodiment does not have a back-side recess 321 formed on the first back surface 32. However, the first shield 30 of this embodiment has a first extension portion 39 at one end and the other end in the first direction D1, extending in a direction intersecting the first direction D1 and the second direction D2, specifically in the third direction D3. These two first extension portions 39 are connected to the first central portion 34 and are provided outside the first back surface 32. Specifically, the first extension portion 39 provided on one side of the first direction D1 is formed on one side of the first direction D1 from the end of the first back surface 32 in the first direction D1. The first extension portion 39 provided on the other side of the first direction D1 is formed on the other side of the first direction D1 from the end of the first back surface 32 in the other direction D1.

[0263] Furthermore, the first extension portion 39 extends in the third direction D3 from the first surface 31 toward the first back surface 32. That is, the first extension portion 39 extends toward the second shield 40. The first extension portion 39 forms a rectangular parallelepiped with the second direction D2 as its extension direction. The two first extension portions 39 are identical in shape and size to each other, and their dimensions in the first direction D1, the second direction D2, and the third direction D3 are all equal.

[0264] The first extension portion 39 is formed by bending a part of the flat plate member of the first shield 30, which is formed by laminating a plurality of flat plate members made of soft magnetic material as described above. Specifically, the first extension portion 39 is formed by bending one or more of the first-2 steel plates 30b to 1-5 steel plates 30e, which are different from the first-5 steel plate 30e that forms the first back surface 32. In this embodiment, as shown in Figure 45, the first extension portion 39 is formed by bending both ends of the first steel plate 30a, which is the furthest from the first-5 steel plate 30e, in the first direction D1 toward the other side in the third direction D3. In other words, the first extension portion 39 is formed by bending both ends of the 1-1 steel plate 30a, which is the outermost of the 1-2 steel plates 30b to the 1-5 steel plates 30e, toward the other side in the third direction D3.

[0265] In contrast, the first-second steel plates 30b to the first-fifth steel plates 30e are formed in a thin plate shape extending in the first direction D1 and the second direction D2, and the ends on both sides in the first direction D1 are not bent. For this reason, the dimension of the first-first steel plate 30a in the first direction D1 is larger than the dimension of the first-second steel plates 30b to the first-fifth steel plates 30e in the first direction D1. Also, the magnetic path length of the first-first steel plate 30a is longer than the magnetic path lengths of the first-second steel plates 30b to the first-fifth steel plates 30e.

[0266] Furthermore, the other end of the first extension 39 in the third direction D3 extends to the first back surface 32. That is, the position of the other end of the first extension 39 in the third direction D3 is the same as the position of the first back surface 32 in the third direction D3. The first-2 steel plates 30b to the first-5 steel plates 30e are arranged in the space between the first extension 39 provided at each end in the first direction D1.

[0267] Furthermore, the two first extensions 39 are formed in a position facing the second extension 46 in the third direction D3. Specifically, the first extension 39 formed on one side of the first shield 30 in the first direction D1 has its other side surface facing the one side surface in the third direction D3 of the second extension 46 formed on one side of the second shield 40 in the first direction D1. Similarly, the first extension 39 formed on the other side of the first shield 30 in the first direction D1 has its other side surface facing the one side surface in the third direction D3 of the second extension 46 formed on the other side of the second shield 40 in the first direction D1.

[0268] In this way, by having a configuration in which the 1-1 steel plate 30a is bent to the other side in the third direction D3 to form a first extension portion 39, the magnetic flux output from the second extension portion 46 is more easily input to the 1-1 steel plate 30a via the first extension portion 39. Consequently, the amount of magnetic flux output from the second extension portion 46 that is input to the 1-5 steel plate 30e forming the first back surface 32 is reduced. As a result, the difference between the amount of magnetic flux input to the 1-5 steel plate 30e and the amount of magnetic flux input to each of the 1-1 steel plates 30a to 1-4 steel plates 30d becomes smaller, and the magnetic flux input to the first shield 30 is homogenized.

[0269] Furthermore, the magnetic flux input to each of the first-1 steel plates 30a to the first-5 steel plates 30e, which are set to have anisotropy, is less likely to be guided to the other steel plates. As a result, the magnetic flux input to each of the first-1 steel plates 30a to the first-4 steel plates 30d is suppressed from being guided in the third direction D3 and input to the first-5 steel plate 30e. Consequently, the first shield 30 is less likely to concentrate magnetic flux on the first back surface 32 compared to a configuration without the first extension portion 39.

[0270] Therefore, in the current detection device 1 of this embodiment, as shown in the hatching in Figure 46, magnetic flux is less likely to concentrate on the first back surface 32 facing the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a. In other words, the first shield 30 is less likely to concentrate magnetic flux in the central part of the first direction D1 on the first back surface 32.

[0271] As a result, magnetic flux is less likely to concentrate on the first back surface 32, thus suppressing magnetic saturation of the first back surface 32. Therefore, the magnetic flux output from the second extension 46 is less likely to leak from the shield magnetic circuit formed by the first shield 30 and the second shield 40. Consequently, the magnetic flux output from the second extension 46 is less likely to be input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a as electromagnetic noise.

[0272] As a result, even when the current flowing through the conductive busbar 50 increases, the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are suppressed from being affected by electromagnetic noise leaked from the shielding magnetic circuit when detecting the magnetic flux of the magnetic field under measurement. Therefore, errors in the magnetic detection signals output by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are suppressed, and the detection accuracy of the current value of the current flowing through the conductive busbar 50, which is calculated based on the magnetic detection signal, can be improved.

[0273] Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with one or two of the first and second embodiments described above.

[0274] (First Modification of the Third Embodiment) In the third embodiment described above, an example was described in which one end and the other end of the first steel plate 30a in the first direction D1 are bent to form the first extension portion 39, but the invention is not limited to this.

[0275] For example, as shown in Figures 47 and 48, the first extension portion 39 may be formed by adding another 1-6 steel plate 30f that is different from the 1-1 steel plate 30a to the 1-5 steel plate 30e. In this case, the 1-6 steel plate 30f shown in Figure 48 is formed in a flat plate shape that extends along the third direction D3. By specifying the rolling direction of the 1-6 steel plate 30f as the third direction D3, the anisotropy of the electromagnetic coefficient is set in the direction that intersects the first direction D1 and the second direction D2, specifically in the third direction D3. Furthermore, the dimension of the 1-6 steel plate 30f in the third direction D3 is set to be the same as the sum of the dimensions of the 1-1 steel plate 30a to the 1-5 steel plate 30e in the third direction D3. The first-sixth steel plate 30f is attached to one end and the other end of each of the first-sixth steel plates 30a to 1st-fifth steel plates 30e in the first direction D1, at a position facing the second extension portion 46 in the third direction D3.

[0276] Furthermore, the dimension of the first-sixth steel plate 30f in the third direction D3 may be set to be smaller or larger than the sum of the dimensions of the third direction D3 of each of the first-first steel plate 30a to the first-fifth steel plate 30e. Also, the thickness of the first-sixth steel plate 30f may be set to be smaller or larger than the dimension of the third direction D3 which is the thickness of each of the first-first steel plate 30a to the first-fifth steel plate 30e.

[0277] By realizing the first extension portion 39 with the first-sixth steel plate 30f formed in this manner, the magnetic flux output from the second extension portion 46 is more easily input to the first-first steel plate 30a to the first-fourth steel plate 30d via the first extension portion 39. Consequently, the amount of magnetic flux input to the first-fifth steel plate 30e, which forms the first back surface 32, from the magnetic flux output from the second extension portion 46 is reduced. As a result, the difference between the amount of magnetic flux input to the first-fifth steel plate 30e and the amount of magnetic flux input to each of the first-first steel plates 30a to the first-fourth steel plates 30d becomes smaller, and the magnetic flux input to the first shield 30 is homogenized. Therefore, the first shield 30 is less prone to magnetic flux concentration on the first back surface 32 compared to a configuration without the first extension portion 39. Therefore, in the current detection device 1 of this embodiment, as shown in the hatching in Figure 49, magnetic flux is less likely to concentrate on the first back surface 32 facing the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0278] Furthermore, the magnetic flux input to each of the first to sixth steel plates 30f, whose anisotropy is set to the third direction D3, is less likely to flow in the first direction D1. For this reason, compared to the configuration described in the third embodiment above, the input of magnetic flux to the first to fifth steel plates 30e is suppressed.

[0279] As a result, magnetic flux is less likely to concentrate on the first back surface 32, thus suppressing magnetic saturation of the first back surface 32. Therefore, the magnetic flux output from the second extension 46 is less likely to leak from the shield magnetic circuit formed by the first shield 30 and the second shield 40. Consequently, the magnetic flux output from the second extension 46 is less likely to be input to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a as electromagnetic noise.

[0280] As a result, even when the current flowing through the conductive busbar 50 increases, the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are suppressed from being affected by electromagnetic noise leaked from the shielding magnetic circuit when detecting the magnetic flux of the magnetic field under measurement. Therefore, errors in the magnetic detection signals output by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are suppressed, and the detection accuracy of the current value of the current flowing through the conductive busbar 50, which is calculated based on the magnetic detection signal, can be improved.

[0281] (Second Modification of the Third Embodiment) In the third embodiment described above, an example was described in which one end and the other end of the 1-1 steel plate 30a in the first direction D1 are bent to form the first extension portion 39, but the invention is not limited to this.

[0282] The first extension portion 39 may be formed by bending one or more of the 1-1 steel plates 30a to 1-4 steel plates 30d, excluding the 1-5 steel plate 30e which forms the first back surface 32. For example, as shown in Figures 50 and 51, the first extension portion 39 may be formed by bending one end and the other end of the 1-2 steel plate 30b in the first direction D1. Alternatively, as shown in Figures 52 and 53, the first extension portion 39 may be formed by bending one end and the other end of the 1-1 steel plate 30a and the 1-2 steel plate 30b in the first direction D1.

[0283] (Third Modification of the Third Embodiment) In the third embodiment described above, an example was described in which the other end of the first extension portion 39 in the third direction D3 extends to the first back surface 32, and the position of the other end in the third direction D3 is the same as the position of the first back surface 32 in the third direction D3. However, the invention is not limited to this example.

[0284] For example, the first extension portion 39 may be formed so that the position of the other end in the third direction D3 is one or the other side of the position of the first back surface 32 in the third direction D3.

[0285] (Perspectives of this Disclosure) As will be apparent from the description of the embodiments above, the disclosures herein include at least the following perspectives:

[0286] [Perspective 2-1] A current detection device comprising: a conductive member (50) having a flat plate shape with one direction of extension as the extension direction through which current flows; magnetic detection units (23, 24) that convert the magnetic field to be measured generated by the flow of the current through the conductive member into a magnetic detection signal; and shielding units (30, 40) that suppress the input of electromagnetic noise to the magnetic detection unit, wherein the shielding units have a plate-shaped first shield (30) and a second shield (40) that are spaced apart from each other and facing each other in predetermined opposing directions, and include portions that extend in the extension direction and in a width direction intersecting the extension direction, respectively; a portion of the conductive member is disposed between the first shield and the second shield; the magnetic detection unit is disposed between the first shield and the second shield and detects a magnetic field that passes through it; the first shield has a first opposing portion (30e) that faces the second shield and forms a first opposing surface (32) that extends in the extension direction and in the width direction, respectively. The current detection device wherein the second shield has a second opposing portion (40e) that faces the first shield and forms a second opposing surface (42) extending in the extension direction and the width direction, respectively, and at least one of the first shield and the second shield has an extended portion (39) that extends in a direction intersecting the extension direction and the width direction, and the extended portion, when provided on the first shield, is positioned outside the first opposing portion, and when provided on the second shield, is positioned outside the second opposing portion.

[0287] [Perspective 2-2] The current detection device according to Perspective 2-1, wherein, of the first and second shields, the shield on which the extended portion is formed is formed by stacking a plurality of flat plate members (30a, 30b, 30c, 30d, 30e, 40a, 40b, 40c, 40d, 40e) in the opposing direction, and the extended portion is formed by bending at least the outermost of the stacked flat plate members from one shield toward the other shield.

[0288] [Perspective 2-3] The current detection device according to Perspective 2-2, wherein when the extended portion is provided on the first shield, a plurality of the stacked flat plate members, excluding the flat plate members forming the first opposing portion, are formed by bending from one shield to the other shield, and when the extended portion is provided on the second shield, a plurality of the stacked flat plate members, excluding the flat plate members forming the second opposing portion, are formed by bending from one shield to the other shield.

[0289] [Perspective 2-4] The current detection device according to any one of the perspectives 2-1 to 2-3, wherein the extension portion is provided at one end in the extension direction and the other end in the extension direction of the shield on which the extension portion is formed.

[0290] (Fourth Embodiment) Next, the fourth embodiment will be described with reference to Figures 54 to 57. In this embodiment, the shapes of the first shield 30 and the second shield 40 differ from those of the first embodiment. Other than this, it is the same as the first embodiment. For this reason, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0291] As shown in Figure 54, the first shield 30 of this embodiment does not have a recessed portion 321 formed on the first back surface 32. That is, in the first shield 30 of this embodiment, the dimensions in the first direction D1 of each of the 1-1 steel plate 30a to 1-5 steel plate 30e are equal to each other.

[0292] Furthermore, as shown in Figures 54 and 55, the second shield 40 of this embodiment has a larger number of electromagnetic steel sheets compared to the first embodiment. Specifically, the second shield 40 of this embodiment is formed by laminating six electromagnetic steel sheets, and one electromagnetic steel sheet is added to one side in the third direction D3 compared to the second shield 40 of the first embodiment.

[0293] Hereinafter, as shown in Figure 55, this added electromagnetic steel sheet will be referred to as the second-sixth steel sheet 40f. The second-sixth steel sheet 40f is made of the same material as the second-first steel sheet 40a to the second-fifth steel sheet 40e. Specifically, the second-sixth steel sheet 40f is made of a soft magnetic material with high magnetic permeability, such as permalloy. In this embodiment, the second shield 40 is formed by stacking the second-first steel sheet 40a to the second-sixth steel sheet 40f in this order from the other side to the one side in the third direction D3. In other words, the second-sixth steel sheet 40f is provided on one side of the second-fifth steel sheet 40e in the third direction D3, which is the part of the second shield 40 that is closest to the conductive busbar 50 when the second-sixth steel sheet 40f is not provided. One side of the second-fifth steel plate 40e in the third direction D3 is the second back surface 42, which is the closest to the conductive busbar 50 than the first back surface 32 of the first shield 30. The second-sixth steel plate 40f is provided between the conductive busbar 50 and the second back surface 42 and faces the conductive busbar 50.

[0294] The second-sixth steel plate 40f is formed in a thin plate shape extending in the first direction D1 and the second direction D2. Unlike the second-second steel plates 40b to the second-fifth steel plates 40e, the second-sixth steel plate 40f is formed without bending the ends on both sides in the first direction D1. Therefore, the second-sixth steel plate 40f in this embodiment does not form part of the second extension portion 46. The second-sixth steel plate 40f is formed to a size that can cover the entire surface on one side in the third direction D3 of the second-fifth central portion 43e of the second-fifth steel plate 40e. Specifically, the dimensions of the second-sixth steel plate 40f in the first direction D1 are approximately equal to the dimensions of the second-fifth central portion 43e in the first direction D1, and the dimensions of the second-fifth steel plate 40f in the second direction D2 are approximately equal to the dimensions of the second-fifth central portion 43e in the second direction D2.

[0295] Furthermore, the anisotropy of the electromagnetic coefficient of the second-sixth steel sheet 40f is set by specifying the rolling direction. The anisotropy of the second-sixth steel sheet 40f is set to the same first direction D1 as the second-first steel sheet 40a to the second-fifth steel sheet 40e, for example.

[0296] As described above, the first shield 30 and the second shield 40 form a closed magnetic shielding circuit around the conductive busbar 50 through which the current flows. When a magnetic field is generated around the conductive busbar 50 due to the flow of current through it, magnetic flux flows in a ring shape within this shielding magnetic circuit, centered on the conductive busbar 50. However, if the first shield 30 and the second shield 40 become magnetically saturated due to the flow of magnetic flux through the shielding magnetic circuit, there is a risk of magnetic flux leaking from the shielding magnetic circuit. For this reason, it is desirable that the shielding magnetic circuit formed by the first shield 30 and the second shield 40 has a structure that makes it difficult for the first shield 30 and the second shield 40 to become magnetically saturated.

[0297] Incidentally, when current flows through the conductive busbar 50 and a magnetic field is generated, there is a magnetic flux that flows directly from the conductive busbar 50 to the first shield 30 and the second shield 40, separate from the magnetic flux flowing through the shield magnetic circuit formed by the first shield 30 and the second shield 40. When this magnetic flux is input to the first shield 30 and the second shield 40, the amount of magnetic flux input to the first shield 30 and the second shield 40 increases, which can cause the first shield 30 and the second shield 40 to become magnetically saturated.

[0298] Here, since the second shield 40 is located at a shorter distance from the conductive busbar 50 compared to the first shield 30, the magnetic flux generated from the conductive busbar 50 is more easily directly input to it. Specifically, the portion of the second shield 40 facing the conductive busbar 50 is more susceptible to direct input of the magnetic flux generated from the conductive busbar 50. Therefore, as the current value flowing through the conductive busbar 50 increases, the magnetic flux directly input to the second shield 40 from the conductive busbar 50 increases, making the portion facing the conductive busbar 50 more prone to magnetic saturation.

[0299] Here, the effects of the current detection device 1 of this embodiment will be explained with reference to Figures 56 to 57. Figure 56 shows a contour plot showing the magnetic flux density when current flows through a comparative current detection device C1 having a comparative second shield C40, which is a comparative example of the second shield 40 of this embodiment. Figure 57 also shows a contour plot showing the magnetic flux density when current flows through the current detection device 1 having the second shield 40 of this embodiment. The comparative current detection device C1 is the same as the current detection device 1 of this embodiment except that the comparative second shield C40 does not have a second-sixth steel plate 40f.

[0300] When a relatively large current flows through the comparative current detection device C1, as shown in Figure 56, the magnetic flux density in the portion of the comparative second shield C40 facing the conductive busbar 50 tends to increase due to the direct input of magnetic flux from the conductive busbar 50. Therefore, when a relatively large current flows through the comparative current detection device C1, the portion of the comparative second shield C40 facing the conductive busbar 50 is prone to magnetic saturation.

[0301] In contrast to the comparative second shield C40, the second shield 40 of this embodiment has a second-sixth steel plate 40f made of a soft magnetic material with high magnetic permeability provided in the portion facing the conductive busbar 50. When an electric current flows through the conductive busbar 50, a magnetic field is generated around the conductive busbar 50, and a magnetic flux is generated that travels directly from the conductive busbar 50 to the second shield 40.

[0302] In a configuration where the second-sixth steel plate 40f is provided in the area facing the conductive busbar 50, the magnetic flux from the conductive busbar 50 toward the second shield 40 is input to the second-sixth steel plate 40f. Thus, when a magnetic field is generated around the conductive busbar 50 due to the flow of current through the conductive busbar 50, the second-sixth steel plate 40f forms a closed magnetic circuit into which the magnetic flux from the conductive busbar 50 is input. That is, the second-sixth steel plate 40f forms a shield magnetic circuit of a different closed magnetic circuit, distinct from the shield magnetic circuit formed by the first shield 30 and the second shield 40. The shield magnetic circuit of the closed magnetic circuit formed by the first shield 30 and the second shield 40 corresponds to the first magnetic circuit. The shield magnetic circuit of the closed magnetic circuit formed by the second-sixth steel plate 40f corresponds to the second magnetic circuit. The magnetic flux input to the second-sixth steel plate 40f is spread and dispersed throughout the entire second-sixth steel plate 40f. This homogenizes the magnetic flux input to the second shield 40.

[0303] Therefore, even when a relatively large current flows through the current detection device 1, as shown in Figure 57, the magnetic flux density of the second-sixth steel plate 40f facing the conductive busbar 50 in the second shield 40 does not easily increase, even when magnetic flux is directly input from the conductive busbar 50. In this embodiment, the second-sixth steel plate 40f corresponds to a magnetic flux suppression section that suppresses the input of magnetic flux from the conductive busbar 50 to the second back surface 42. Therefore, even when a relatively large current flows through the current detection device 1, the portion of the second shield 40 facing the conductive busbar 50 is less likely to become magnetically saturated. Consequently, the magnetic flux output from the first shield 30 is suppressed from being input as electromagnetic noise to the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a.

[0304] As a result, even when the current flowing through the conductive busbar 50 increases, the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are suppressed from being affected by electromagnetic noise leaked from the shielding magnetic circuit when detecting the magnetic flux of the magnetic field under measurement. Therefore, errors in the magnetic detection signals output by the first magnetoelectric conversion unit 231a and the second magnetoelectric conversion unit 241a are suppressed, and the detection accuracy of the current value of the current flowing through the conductive busbar 50, which is calculated based on the magnetic detection signal, can be improved.

[0305] Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with any one or two of the first to third embodiments described above.

[0306] (First Modification of the Fourth Embodiment) In the fourth embodiment described above, an example was described in which the second-sixth steel plate 40f laminated on the second-fifth steel plate 40e forms a shielding magnetic circuit of a closed magnetic path when a magnetic field is generated around the conductive busbar 50, thereby suppressing the input of magnetic flux from the conductive busbar 50 to the second back surface 42. However, the invention is not limited to this.

[0307] For example, a shield member separate from the second shield 40 may be provided on the second back surface 42. In this case, when a magnetic field is generated around the conductive busbar 50, this shield member may form a shield magnetic circuit that is a closed magnetic circuit, separate from the shield magnetic circuit formed by the first shield 30 and the second shield 40, thereby suppressing the input of magnetic flux from the conductive busbar 50 to the second back surface 42. In other words, the magnetic flux suppression part that suppresses the input of magnetic flux from the conductive busbar 50 to the second back surface 42 does not have to be formed integrally with the second shield 40.

[0308] (Second Modification of the Fourth Embodiment) In the fourth embodiment described above, a second-sixth steel plate 40f that functions as a magnetic flux suppression part is provided on the second back surface 42 of the second shield 40, and a configuration has been described in which the input of magnetic flux from the conductive busbar 50 to the second back surface 42 is suppressed, but the invention is not limited to this.

[0309] For example, the first back surface 32 of the first shield 30 may also be provided with a shielding member that functions as a magnetic flux suppression unit, and this shielding member may be used to suppress the input of magnetic flux from the conductive busbar 50 to the first back surface 32. In this case, this shielding member may be laminated on the first-fifth steel plate 30e and formed integrally with the first shield 30, or it may be formed separately from the first shield 30.

[0310] (Third Modification of the Fourth Embodiment) In the fourth embodiment described above, an example was described in which the back-side recess 321 described in the first embodiment is not formed on the first shield 30. Also, in the fourth embodiment described above, an example was described in which the extended recess 461 described in the second embodiment is not formed on the second shield 40. However, the invention is not limited thereto.

[0311] As shown in Figure 58, the first shield 30 may have a back-side recess 321 formed on the first back surface 32, similar to the first embodiment. In this case, as shown in Figure 59, an extended recess 461 may be formed on the second extended portion 46, similar to the second embodiment.

[0312] (Perspectives of this Disclosure) As will be apparent from the description of the embodiments above, the disclosures herein include at least the following perspectives:

[0313] [Perspective 3-1] A current detection device comprising: a conductive member (50) having a flat plate shape with one direction of extension as the extension direction through which current flows; magnetic detection units (23, 24) that convert the magnetic field to be measured generated by the flow of the current through the conductive member into a magnetic detection signal; shielding units (30, 40) that suppress the input of electromagnetic noise to the magnetic detection unit; and a magnetic flux suppression unit (40f) that suppresses the input of magnetic flux from the conductive member to the shielding unit, wherein the shielding units have plate-shaped first shield (30) and second shield (40) that are spaced apart from each other and facing each other in predetermined opposing directions, and include portions that extend in the extension direction and in the width direction intersecting the extension direction, respectively, and when the current flows through the conductive member, it forms a first magnetic circuit of a closed magnetic path surrounding the magnetic detection unit, a portion of the conductive member is disposed between the first shield and the second shield, and the magnetic detection unit is disposed between the first shield and the second shield and detects the magnetic field that passes through it. The current detection device comprises a first shield having a first opposing surface (32) facing the second shield, a second shield having a second opposing surface (42) facing the first shield, and a magnetic flux suppression unit provided between the first opposing surface and the second opposing surface, at least the opposing surface closer to the conductive member, and the conductive member, wherein when the current flows through the conductive member, it forms a second magnetic circuit of a closed magnetic path and suppresses the input of magnetic flux from the conductive member to the first magnetic circuit.

[0314] [Perspective 3-2] The current detection device according to Perspective 3-1, wherein, of the first shield and the second shield, the shield on which the magnetic flux suppression portion is provided is formed by stacking a plurality of flat plate members (30a, 30b, 30c, 30d, 30e, 40a, 40b, 40c, 40d, 40e) in the opposing direction, the anisotropy of the magnetic permeability being in the width direction, and the magnetic flux suppression portion extends in the extension direction and the width direction along the first opposing surface and the second opposing surface, and the anisotropy of the magnetic permeability is the anisotropy of the magnetic permeability of the flat plate members.

[0315] (Other Embodiments) Although typical embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above and can be modified in various ways, for example, as follows.

[0316] In the above-described embodiment, an example was described in which the first shield 30 and the second shield 40 are constructed by laminating a plurality of flat plate members made of a soft magnetic material, but the invention is not limited to this. For example, the first shield 30 and the second shield 40 may be manufactured by rolling a single sheet of electromagnetic steel made of a soft magnetic material.

[0317] In the above-described embodiment, an example was given in which the current detection device 1 is applied to a battery management system VMS that manages the temperature of the battery VT, but the invention is not limited to this. The current detection device 1 may be applied to various temperature management systems other than the battery management system VMS, or to various circuit systems through which current flows other than temperature management systems.

[0318] In the above-described embodiment, an example was given in which the conductive busbar 50 is composed of a busbar made of a conductive material such as copper, brass, and aluminum, but the invention is not limited to this. For example, the conductive busbar 50 may be composed of a shunt resistance element made of a copper alloy containing manganese, nickel, etc., which has conductivity and significantly higher electrical resistance than copper, brass, and aluminum. In this case, the conductive busbar 50 is configured to sandwich the shunt resistance element between conductive materials such as copper, brass, and aluminum in the second direction D2, making it easier to raise the temperature of the shunt resistance element by allowing current to flow through the conductive busbar 50. Based on this change in the temperature of the shunt resistance element, the current value of the current flowing through the conductive busbar 50 can be detected.

[0319] In the above-described embodiment, an example was given in which the second shield 40 has a second extension portion 46, but the invention is not limited thereto. For example, the second shield 40 may not have a second extension portion 46 and may be formed in a flat plate shape extending in the first direction D1 and the second direction D2.

[0320] In the embodiments described above, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are explicitly stated to be essential or where they are clearly considered essential in principle.

[0321] In the embodiments described above, if numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated as particularly essential or clearly limited to a specific number in principle.

[0322] In the embodiments described above, when referring to the shape, positional relationships, etc. of the components, the definition is not limited to those shapes, positional relationships, etc., unless otherwise specifically stated or when the definition is fundamentally limited to a particular shape, positional relationship, etc.

[0323] The first sensing unit 23 and the second sensing unit 24 and their methods of this disclosure may be implemented in a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. The first sensing unit 23 and the second sensing unit 24 and their methods of this disclosure may be implemented in a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. The first sensing unit 23 and the second sensing unit 24 and their methods of this disclosure may be implemented in one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0324] (Perspective of this disclosure) The above disclosure can be understood from the following perspectives, for example.

[0325] [First Perspective] A current detection device comprising: a conductive member (50) having a flat plate shape with one direction of extension as the extension direction through which current flows; magnetic detection units (23, 24) that convert the magnetic field to be measured generated by the flow of the current through the conductive member into a magnetic detection signal; and shielding units (30, 40) that suppress the input of electromagnetic noise to the magnetic detection units, wherein the shielding units have a plate-shaped first shield (30) and a second shield (40) that are spaced apart from each other and facing each other in predetermined opposing directions, and include portions that extend in the extension direction and in a width direction intersecting the extension direction, respectively; a portion of the conductive member is disposed between the first shield and the second shield; the magnetic detection unit is disposed between the first shield and the second shield and detects the magnetic field that passes through it; the first shield has a first opposing surface (32) that faces the second shield; and the second shield has a second opposing surface (42) that faces the first shield. A current detection device wherein at least one of the first opposing surface and the second opposing surface has a recessed portion (321) formed in the opposing direction, and the recessed portion is formed in a position that does not overlap with the magnetic detection portion in the opposing direction.

[0326] [Second viewpoint] The current detection device according to the first viewpoint, wherein the shield in which the recess is formed is formed by stacking a plurality of flat plate members (30a, 30b, 30c, 30d, 30e, 40a, 40b, 40c, 40d, 40e) in the opposing direction, the anisotropy of the magnetic permeability being in the width direction, and the recess is formed in the flat plate members that form the first opposing surface and the second opposing surface among the plurality of flat plate members.

[0327] [Third viewpoint] The current detection device according to the first or second viewpoint, wherein the recess is formed in the first shield, and the second shield has an extension (46) extending toward the first shield at one end and the other end in the width direction.

[0328] [Fourth viewpoint] The current detection device according to the third viewpoint, wherein the recessed portion is formed at one end and the other end in the width direction.

[0329] [Fifth viewpoint] The current detection device according to any one of the first to fourth viewpoints, wherein the recess is formed by cutting out from one end in the extension direction to the other end.

[0330] [Sixth viewpoint] The current detection device according to any one of the first to fourth viewpoints, wherein the recess is formed such that its length in the extension direction is smaller than the length of the shield on which the recess is formed.

[0331] [Seventh viewpoint] The current detection device according to any one of the third to sixth viewpoints, wherein the extended portion has an extended recess (461) formed in the opposite direction.

[0332] [Eighth viewpoint] The current detection device according to the seventh viewpoint, wherein the extended recess is formed on the inside of the extended portion.

[0333] [Ninth Aspect] The current detection device according to the eighth aspect, wherein the shield in which the recess is formed is made up of a plurality of flat plate members (30a, 30b, 30c, 30d, 30e, 40a, 40b, 40c, 40d, 40e) having anisotropy of magnetic permeability in the width direction, stacked in the opposing direction, the extended portion is made up of the first shield and the second shield by bending, and the recess is made up of a cutout in at least the innermost of the stacked flat plate members.

[0334] [Tenth viewpoint] A current detection device according to any one of the first to ninth viewpoints, comprising a magnetic flux suppression unit (40f) that suppresses the input of magnetic flux from the conductive member to the shield unit, the first shield and the second shield form a first magnetic circuit of a closed magnetic path surrounding the magnetic detection unit when the current flows through the conductive member, and the magnetic flux suppression unit is provided between the conductive member and at least the opposing surface of the first opposing surface and the second opposing surface that is closer to the conductive member, and forms a second magnetic circuit of a closed magnetic path when the current flows through the conductive member, thereby suppressing the input of magnetic flux from the conductive member to the first magnetic circuit.

[0335] [Aspect 11] The current detection device according to any one of the first to tenth aspects, wherein the dimension of the central portion in the width direction in the extension direction of the first shield is greater than the dimensions of the extension direction of each of the end portions in the width direction.

[0336] [Twelfth viewpoint] The current detection device according to the eleventh viewpoint, wherein the first shield is formed by cutting out the four corners.

[0337] [13th viewpoint] The current detection device according to any one of the first to 12th viewpoints, wherein the second shield has an extension dimension of the central portion in the width direction that is greater than the extension dimensions of each of the end portions in the width direction.

[0338] [Aspect 14] A current detection device according to any one of the first to thirteenth aspects, comprising a current detection unit (25) that outputs a current detection signal corresponding to the current flowing through the conductive member based on the electrical resistance value of the conductive member and the voltage applied to the conductive member.

Claims

1. A current detection device comprising: a conductive member (50) having a flat plate shape with one direction of extension as the extension direction through which current flows; magnetic detection units (23, 24) that convert the magnetic field to be measured generated by the flow of the current through the conductive member into a magnetic detection signal; and shielding units (30, 40) that suppress the input of electromagnetic noise to the magnetic detection unit, wherein the shielding units have a plate-shaped first shield (30) and a second shield (40) that are spaced apart from each other and facing each other in predetermined opposing directions, and include portions that extend in the extension direction and in a width direction intersecting the extension direction, respectively; a portion of the conductive member is disposed between the first shield and the second shield; the magnetic detection unit is disposed between the first shield and the second shield and detects the magnetic field that passes through it; the first shield has a first opposing surface (32) that faces the second shield; and the second shield has a second opposing surface (42) that faces the first shield. A current detection device wherein at least one of the first opposing surface and the second opposing surface has a recessed portion (321) formed in the opposing direction, and the recessed portion is formed in a position that does not overlap with the magnetic detection portion in the opposing direction.

2. The current detection device according to claim 1, wherein, of the first shield and the second shield, the shield on which the recess is formed is formed by stacking a plurality of flat plate members (30a, 30b, 30c, 30d, 30e, 40a, 40b, 40c, 40d, 40e) in the opposing direction, the anisotropy of the magnetic permeability being in the width direction, and the recess is formed in the flat plate members that form the first opposing surface and the second opposing surface among the plurality of flat plate members.

3. The current detection device according to claim 1, wherein the recess is formed in the first shield, and the second shield has an extended portion (46) extending toward the first shield at each of its ends in the width direction.

4. The current detection device according to claim 3, wherein the recessed portion is formed at one end and the other end in the width direction.

5. The current detection device according to claim 1, wherein the recess is formed by cutting out from one end to the other end in the extension direction.

6. The current detection device according to claim 1, wherein the recess is formed such that the dimension in the extension direction is smaller than the dimension in the extension direction of the shield on which the recess is formed.

7. The current detection device according to claim 3, wherein the extended portion has an extended recess portion (461) formed in the opposite direction.

8. The current detection device according to claim 7, wherein the extended recess is formed on the inside of the extended portion.

9. The current detection device according to claim 8, wherein, of the first shield and the second shield, the shield in which the recess is formed is formed by stacking a plurality of flat plate members (30a, 30b, 30c, 30d, 30e, 40a, 40b, 40c, 40d, 40e) in the opposing direction, the extension is formed by bending the first shield and the second shield, and the recess is formed by cutting out at least the innermost of the stacked flat plate members.

10. The current detection device according to claim 1, further comprising a magnetic flux suppression unit (40f) that suppresses the input of magnetic flux from the conductive member to the shield unit, wherein the first shield and the second shield form a first magnetic circuit, a closed magnetic path surrounding the magnetic detection unit, when the current flows through the conductive member, and the magnetic flux suppression unit is provided between at least the opposing surface of the first opposing surface and the second opposing surface that is closer to the conductive member and the conductive member, and when the current flows through the conductive member, it forms a second magnetic circuit, a closed magnetic path, and suppresses the input of magnetic flux from the conductive member to the first magnetic circuit.

11. The current detection device according to claim 1, wherein the dimension of the central portion in the width direction of the first shield in the extension direction is greater than the dimensions of the extension directions of each of the end portions in the width direction.

12. The current detection device according to claim 11, wherein the first shield is formed by cutting out four corners.

13. The current detection device according to claim 1, wherein the dimension of the central portion in the width direction of the second shield in the extension direction is greater than the dimensions of the extension directions of each of the end portions in the width direction.

14. A current detection device according to any one of claims 1 to 13, comprising a current detection unit (25) that outputs a current detection signal corresponding to the current flowing through the conductive member based on the electrical resistance value of the conductive member and the voltage applied to the conductive member.

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