Current sensor

Abstract

To provide a current sensor with which it is suppressed that the flux density of a magnetic field around other detection object is superimposed on the flux density of a magnetic field around a prescribed detection object to be detected by a sensor element.SOLUTION: The current sensor comprises: a bus bar 30; and a sensor module 50 having a hall sensor 20 that includes a sensor element. The bus bar includes a detection object part 32 at which a magnetic field is to be detected, an inflow part 31 connected to the detection object part at a position closer to a current inflow side than the detection object part, and an outflow part 33 connected to the detection object part at a position closer to a current outflow side than the detection object part. The detection object part has an open hole 34 which the hall sensor is put through in its own plate thickness direction Y. A plurality of sensor modules are arranged in such a way that the magnetic fields generated around the respective detection object parts do not interfere with each other.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The disclosure described in this specification relates to a current sensor.

Background Art

[0002] The current sensor of Patent Document 1 has three conductors and three magnetoelectric conversion units that measure the current flowing through each of the three conductors. Each magnetoelectric conversion unit incorporates two magnetic detection elements. When a current flows through a conductor, a magnetic field is generated around the conductor according to the magnitude of the current. The magnetic detection element detects the magnetic flux density of the magnetic flux in such a magnetic field.

[0003] The magnetoelectric conversion unit is configured to output a signal according to the difference in the magnetic flux density input to the two magnetic detection elements. The directions of the magnetic fluxes of the external magnetic fields generated by another conductor, which are input to the detection surfaces of the two magnetic detection elements of the magnetoelectric conversion unit arranged on one conductor, are all in the same direction. Each of the detection results of the two magnetic detection elements is input to the inverting terminal and the non-inverting terminal of the amplifier, and a differential magnetic flux is detected. Therefore, the magnetic fluxes of these external magnetic fields are canceled out and output.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there is a slight difference between the magnetic flux density of the external magnetic field input to one magnetic detection element and the magnetic flux density of the external magnetic field input to another magnetic detection element. Therefore, even if the directions of the magnetic fluxes of these two external magnetic fields are both in the same direction, the differential magnetic flux does not become zero. There is a possibility that the magnetic flux density of the external magnetic field is superimposed on the magnetic flux density of the magnetic field around the conductor to be detected by the magnetic detection element.

[0006] Therefore, an object of the present disclosure is to provide a current sensor in which the magnetic flux density of the magnetic field around another detection target portion is suppressed from overlapping the magnetic flux density of the magnetic field around a predetermined detection target portion to be detected by a sensor element.

Means for Solving the Problems

[0007] A current sensor according to an aspect of the present disclosure is a current sensor (100) including a plurality of sensor modules (50) each having a Hall sensor (20) including a bus bar (30) through which a current flows and sensor elements (21, 22) for detecting a magnetic field generated around the bus bar, wherein the bus bar has a detection target portion (32) to be a target for detecting a magnetic field, an inflow portion (31) connected to the detection target portion on the current inflow side of the detection target portion, and an outflow portion (33) connected to the detection target portion on the current outflow side of the detection target portion, the detection target portion has a through hole (34) through which the Hall sensor passes in its plate thickness direction (Y), and a plurality of sensor modules are arranged so that the magnetic fields generated around the detection target portions do not interfere with each other.

[0008] According to this, interference between the magnetic fields generated around the detection target portions (32) is suppressed. Therefore, the magnetic flux density of the magnetic field generated around another detection target portion is suppressed from overlapping the magnetic flux density of the magnetic field generated around a predetermined detection target portion to be detected by a predetermined Hall sensor (20).

[0009] Note that the reference numerals in the parentheses above only indicate the correspondence with the configurations described in the embodiments below, and do not limit the technical scope in any way.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Modes for Carrying Out the Invention

[0011] Hereinafter, a plurality of modes for carrying out the present disclosure will be described with reference to the drawings. In each mode, parts corresponding to those described in the preceding mode may be denoted by the same reference numerals and redundant descriptions may be omitted. When only a part of the configuration is described in each mode, other modes described previously can be applied to other parts of the configuration.

[0012] In addition, not only combinations of parts clearly indicated as combinable in each embodiment are possible, but also embodiments, embodiments and variations, and variations can be partially combined with each other as long as there is no problem with the combination, even if not explicitly stated.

[0013] (First Embodiment) FIG. 1 is an electrical circuit diagram of the power conversion device 1. The power conversion device 1 is mounted on a vehicle such as an electric vehicle or a hybrid vehicle. The power conversion device 1 performs power conversion between the battery 2 and the motor generator 3. The power conversion device 1, together with the battery 2 and the motor generator 3, constitutes a drive system of the vehicle.

[0014] The battery 2 is a rechargeable secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The motor generator 3 is a rotating electrical machine of a three-phase AC system. The motor generator 3 may be referred to as a multi-phase motor. The motor generator 3 functions as a driving source for the vehicle, that is, an electric motor. The motor generator 3 functions as a generator during regeneration.

[0015] The power conversion device 1 includes a capacitor 4, an inverter 5, three hall sensors 20, three output busbars 30, a sensor substrate 40, a sealing member 60, and a circuit board 70. The capacitor 4 smoothes, for example, the DC current supplied from the battery 2. The positive terminal of the capacitor 4 is connected to the positive electrode, which is the high-potential side electrode of the battery 2. The negative terminal of the capacitor 4 is connected to the negative electrode, which is the low-potential side electrode of the battery 2.

[0016] The inverter 5 is a DC-AC conversion unit that converts the supplied DC power into three-phase AC of a predetermined frequency. The inverter 5 outputs the power converted from DC power to AC power to the motor generator 3. The inverter 5 also converts the AC power generated by the motor generator 3 into DC power. The inverter 5 is configured to include upper and lower arm circuits 6A. The upper and lower arm circuits 6 may be referred to as legs. The upper and lower arm circuits 6A of each phase are formed by connecting an upper arm 6H and a lower arm 6L in series between a high-potential power busbar 11, which is a power line on the positive electrode side, and a low-potential power busbar 12, which is a power line on the negative electrode side.

[0017] As an example, the inverter 5 includes a three-phase upper and lower arm circuit 6A. The three-phase upper and lower arm circuit 6A includes a U-phase upper and lower arm circuit, a V-phase upper and lower arm circuit, and a W-phase upper and lower arm circuit. Note that the three-phase upper and lower arm circuit 6A is individually coated with a resin member to form a semiconductor module. The three-phase semiconductor modules may be collectively referred to as a power module.

[0018] In this embodiment, as an example of the switching element constituting each arm 6H, 6L, an n-channel insulated gate bipolar transistor 7 (hereinafter referred to as IGBT7) is adopted. A freewheeling diode FWD7D is connected in anti-parallel to each of the IGBT7s. The upper and lower arm circuit 6A for one phase has two IGBT7s.

[0019] In the upper arm 6H, a first input terminal is connected to the collector of the IGBT7. The high-potential power bus bar 11 and the collector of the IGBT7 are electrically connected via the first input terminal. In the lower arm 6L, a second input terminal is connected to the emitter of the IGBT7. The low-potential power bus bar 12 and the emitter of the IGBT7 are electrically connected via the second input terminal. An output terminal is connected to the midpoint between the upper arm 6H and the lower arm 6L. The output terminal and the motor generator 3 are electrically connected via the output bus bar 30.

[0020] Also, a gate terminal is connected to the gate of the IGBT7 in the upper arm 6H. A gate terminal is connected to the gate of the IGBT7 in the lower arm 6L. The gate terminal connected to the IGBT7 in the upper arm 6H and the gate terminal connected to the IGBT7 in the lower arm 6L are electrically connected to the circuit board 70.

[0021] The circuit board 70 is provided with a control circuit that controls the on / off of the IGBT via a gate terminal. The power conversion device 1 can supply three-phase alternating currents with different periods to the motor generator 3 via the output bus bar 30 by controlling the on or off of a plurality of IGBTs 7 by the control circuit. Note that the circuit board 70 may be provided with a drive circuit for driving the IGBT 7 in addition to the control circuit. The drive circuit supplies a drive voltage to the gate of the IGBT 7 of the corresponding arm 6H, 6L based on the drive command of the control circuit. The drive circuit drives the corresponding IGBT 7, that is, turns it on or off, by applying the drive voltage. The drive circuit may be referred to as a driver.

[0022] The output bus bar 30 connects the upper and lower arm circuits 6A and each phase of the motor generator 3. A hall sensor 20 is provided on the output bus bar 30. The three output bus bars 30, the three hall sensors 20, the sensor board 40, and the sealing member 60 may be collectively referred to as a current sensor 100. One output bus bar 30 and one hall sensor 20 may be referred to as a sensor module 50. The current sensor 100 includes three sensor modules 50, a sensor board 40, and a sealing member 60.

[0023] The mechanical configuration of the current sensor 100 will be described below. FIG. 2 is a perspective view of the current sensor 100. FIG. 3 is a schematic view of the current sensor 100 excluding the sensor board 40 and the sealing member 60. FIG. 4 is a cross-sectional view taken along the cross-section shown in FIG. 2. FIG. 5 is a wiring diagram of the hall sensor 20. FIG. 6 is a graph showing the magnitude of the magnetic flux density with respect to the distance between the hall sensor 20 and the second extension 32.

[0024] The output bus bar 30 is a conductive member formed of a metal material such as copper having conductivity. The output bus bar 30 forms a current-carrying path through which current flows. The output bus bar 30 is plate-shaped with a small thickness in the plate thickness direction. The output bus bar 30 has a short side in one direction orthogonal to the plate thickness direction. The output bus bar 30 has a long side in a direction orthogonal to the plate thickness direction and the short side direction. The output bus bar 30 is elongated in the longitudinal direction. The output bus bar 30 is formed by performing punching or bending on a metal member such as copper.

[0025] The output bus bar 30 in the first embodiment has a first extension portion 31, a second extension portion 32, and a third extension portion 33. The first extension portion 31, the second extension portion 32, and the third extension portion 33 are continuous in this order with the same material. Note that the form of the output bus bar 30 shown below is merely an example and is not limited thereto.

[0026] Hereinafter, the plate thickness direction of the second extension portion 32 may be referred to as the Y direction. The Y direction corresponds to the longitudinal direction of the first extension portion 31 and the third extension portion 33. The Y direction may be referred to as the first extension direction and the third extension direction. The longitudinal direction of the second extension portion 32 among the directions orthogonal to the Y direction may be referred to as the X direction. The X direction may be referred to as the second extension direction. The short side direction of the second extension portion 32 among the directions orthogonal to the Y direction may be referred to as the Z direction. The Z direction corresponds to the plate thickness direction of the first extension portion 31 and the third extension portion 33. The X direction, the Y direction, and the Z direction are three mutually orthogonal directions.

[0027] The second extension portion 32 has a plate-like shape with a small thickness in the Y direction. The second extension portion 32 has a first surface 32A and a second surface 32B spaced apart in the Y direction. A through hole 34 penetrating the first surface 32A and the second surface 32B in the Y direction is formed in the second extension portion 32. The through hole 34 is a hole for passing the hall sensor 20. It can also be said that the second extension portion 32 has a frame shape surrounding the through hole 34 in an annular shape. In the X direction, the through hole 34 is disposed substantially at the center of the second extension portion 32. Note that the arrangement of the through hole 34 is not limited to being substantially at the center. In a plan view in the Y direction, the through hole 34 has a substantially rectangular shape.

[0028] The second extension part 32 has one end and the other end spaced apart in the X direction. The first extension part 31 is connected to a part on one end side of the second extension part 32 rather than the through hole 34. The third extension part 33 is connected to a part on the other end side of the second extension part 32 rather than the through hole 34.

[0029] The first extension part 31 is connected to the first surface 32A on one end side rather than the through hole 34. The first extension part 31 extends in the Y direction so as to be away from the first surface 32A. The first extension part 31 has a thickness in the Z direction. The first extension part 31 has a width in the X direction. The third extension part 33 is connected to the second surface 32B on the other end side rather than the through hole 34. The third extension part 33 extends in the Y direction so as to be away from the second surface 32B. The third extension part 33 has a thickness in the Z direction. The third extension part 33 has a width in the X direction. Note that the output bus bar 30 is not limited to a configuration having the first extension part 31, the second extension part 32, and the third extension part 33. The output bus bar 30 may have a configuration having only the second extension part 32.

[0030] In the first embodiment, the through hole 34 has a width in the X direction and has four corners 37A, 37B, 37C, and 37D. The second extension part 32 has an upper piece 35 and a lower piece 36 arranged in the Z direction via the through hole 34. The direction in which the upper piece 35 and the lower piece 36 are arranged may be referred to as the vertical direction. The vertical direction corresponds to the Z direction. The corner 37A is located on the third extension part 33 side of the upper piece 35. The corner 37B is located on the first extension part 31 side of the upper piece 35. The corner 37C is located on the first extension part 31 side of the lower piece 36. The corner 37D is located on the third extension part 33 side of the lower piece 36. The first extension part 31 is closest to the corner 37C among the four corners 37, and the third extension part 33 is closest to the corner 37A among the four corners 37. The first extension part 31 and the third extension part 33 have a width in the X direction.

[0031] The edge of the through hole 34 on the side of the first extension portion 31 and the X-direction position of the end portion of the first extension portion 31 on the side of the through hole 34 are almost the same. The edge of the through hole 34 on the side of the third extension portion 33 and the X-direction position of the end portion of the third extension portion 33 on the side of the through hole 34 are almost the same. The hall sensor 20 is disposed substantially at the center in the X direction in the through hole 34. The first extension portion 31 and the hall sensor 20 do not overlap in the Z direction. The third extension portion 33 and the hall sensor 20 do not overlap in the Z direction.

[0032] The current flows from the first extension portion 31 toward the third extension portion 33 along the longitudinal direction of the output bus bar 30. A magnetic field is formed in the circumferential direction around the longitudinal direction by the current flowing in the longitudinal direction of the output bus bar 30. The current flows along the Y direction in the first extension portion 31, the X direction in the second extension portion 32, and the Y direction in the third extension portion 33. In the first extension portion 31 and the third extension portion 33, a magnetic field is formed in the circumferential direction around the Y direction.

[0033] The hall sensor 20 detects the magnetic flux density of the magnetic field generated by the current flowing in the second extension portion 32. A magnetic field is formed in the circumferential direction around the Y direction by the current flowing in the Y direction in the second extension portion 32. The second extension portion 32 has an upper piece 35 and a lower piece 36 arranged in the Z direction via the through hole 34. The hall sensor 20 detects the magnetic flux density of the magnetic field generated by the current flowing through the upper piece 35 and the lower piece 36. Also, since the first extension portion 31 is provided on the side where the current flows in rather than the second extension portion 32, it may be referred to as the inflow portion. Since the third extension portion 33 is provided on the side where the current flows out rather than the second extension portion 32, it may be referred to as the outflow portion.

[0034] The hall sensor 20 is individually provided in the through holes 34 of the three output bus bars 30. In the present embodiment, the hall sensor 20 detects the current flowing in the second extension portion 32 and detects the magnetic flux density of the magnetic field generated around the second extension portion 32. Since the second extension portion 32 is the target portion where the magnetic flux density is detected, it may be referred to as the detection target portion. The hall sensor 20 does not have a magnetic core for converging the magnetic field and is a coreless type current sensor.

[0035] The Hall sensor 20 has sensor elements 21 and 22, a signal processing IC 23, and a package 24. The sensor elements 21 and 22 are magnetic sensors that detect a magnetic field. The sensor elements 21 and 22 detect the magnetic flux of the magnetic field and output a detection signal corresponding to the magnetic flux density. The sensor elements 21 and 22 are elements that convert a magnetic signal into an electrical signal and may be referred to as magnetoelectric conversion elements. The sensor elements 21 and 22 are, for example, Hall elements. The sensor elements 21 and 22 have a detection direction in the Z direction. The sensor elements 21 and 22 can detect the magnetic flux along the Z direction.

[0036] The detection signals of the sensor elements 21 and 22 include information regarding the component extending in the Z direction among the magnetic fluxes passing through the sensor elements 21 and 22, while not including information regarding the component orthogonal to the detection direction. That is, the sensor elements 21 and 22 detect the component extending in the detection direction among the magnetic fluxes linked to the sensor elements 21 and 22, while not detecting the component orthogonal to the detection direction. One Hall sensor 20 has a first sensor element 21 and a second sensor element 22 as the sensor elements 21 and 22. Note that the number of sensor elements included in the Hall sensor 20 is not limited to two, and the Hall sensor 20 may include three or more sensor elements.

[0037] The sensor elements 21 and 22 are mainly made of a semiconductor material. When the sensor elements 21 and 22 reach a certain temperature or higher, their performance cannot be fully exhibited. The limit temperature at which the performance of the sensor elements 21 and 22 can be fully exhibited is called the heat-resistant temperature. In the Hall sensor 20, it is necessary to detect the magnetic flux density around the second extension portion 32 within a range not exceeding the heat-resistant temperature of the sensor elements 21 and 22. Therefore, it is desirable not to provide a portion with high thermal resistance in the second extension portion 32.

[0038] In the present embodiment, a minimum through hole 34 for passing the later-described branch portions 42, 43, 43 and the Hall sensor 20 is formed in the second extension portion 32. The present embodiment can suppress a decrease in the cross-sectional area as compared with providing a notch structure in the second extension portion 32 that involves a significant decrease in the cross-sectional area. In the present embodiment, by providing the minimum through hole 34, an increase in the thermal resistance of the second extension portion 32 is suppressed. Along with this, the heat generation amount of the Hall sensor 20 is reduced, leading to an improvement in the output of the Hall sensor 20.

[0039] The package 24 is formed in a rectangular parallelepiped shape with a small thickness in the Z direction by a resin material or the like. The package 24 houses the sensor elements 21, 22 in a state of covering them. Inside the package 24, the sensor elements 21, 22 are arranged spaced apart in the Y direction. The package 24 protects the sensor elements 21, 22 in a state where the sensor elements 21, 22 can detect the magnetic flux density. The first sensor element 21 and the second sensor element 22 are provided on opposite sides via the second extension portion 32 with respect to the Y direction. As an example, the first sensor element 21 is provided on the side of the first extension portion 31 with respect to the Y direction rather than the second sensor element 22. The second sensor element 22 is provided on the side of the third extension portion 33 with respect to the Y direction rather than the first sensor element 21. The package 24 is mounted on the sensor substrate 40 so as to overlap in the Z direction. The sensor substrate 40 is arranged on the lower piece 36 side rather than the package 24. The package 24 is surface-mounted on the surface of the sensor substrate 40 that faces the package 24.

[0040] The two sensor elements 21, 22 have a detection surface 25 into which the magnetic flux of the second extension portion 32 is input. The two sensor elements 21, 22 are arranged in the package 24 such that the detection surface 25 of the first sensor element 21 and the detection surface 25 of the second sensor element 22 face the same direction. In the present embodiment, the detection surfaces 25 of the two sensor elements 21, 22 are arranged to face the Z direction. The detection surfaces 25 of the two sensor elements 21, 22 extend along the XY plane.

[0041] The second extension part 32 branches into an upper piece 35 and a lower piece 36 at the part where the through hole 34 is formed. In the upper piece 35 and the lower piece 36, the current flows along the X direction. In the upper piece 35 and the lower piece 36, a magnetic field is formed in the circumferential direction around the X direction. In the first extension part 31, the second extension part 32, and the third extension part 33, a magnetic field in the direction as shown in FIG. 3 is generated. The direction of the current flowing in the upper piece 35 is the same as the direction of the current flowing in the lower piece 36.

[0042] The direction of the magnetic flux of the magnetic field around the upper piece 35 input to the first sensor element 21 is opposite to the direction of the magnetic flux of the magnetic field around the lower piece 36 input to the second sensor element 22. Due to the magnetic field formed around the upper piece 35, magnetic flux in the direction from the sensor substrate 40 toward the Hall sensor 20 is input to the first sensor element 21. Due to the magnetic field formed around the upper piece 35, magnetic flux in the direction from the Hall sensor 20 toward the sensor substrate 40 is input to the second sensor element 22. Due to the magnetic field formed around the lower piece 36, magnetic flux in the direction from the sensor substrate 40 toward the Hall sensor 20 is input to the first sensor element 21. Due to the magnetic field formed around the lower piece 36, magnetic flux in the direction from the Hall sensor 20 toward the sensor substrate 40 is input to the second sensor element 22.

[0043] Magnetic flux obtained by adding the magnetic flux around the upper piece 35 and the magnetic flux around the lower piece 36 is input to the two sensor elements 21 and 22. The Hall sensor 20 has a signal processing IC 23 that is controlled to output a signal according to the difference in the magnetic flux density input to the two sensor elements 21 and 22. Note that the signal processing IC 23 may be referred to as an output part. As shown in FIG. 5, in the Hall sensor 20, the two sensor elements 21 and 22 are connected via wiring. The detection results of the two sensor elements 21 and 22 are input to the inverting terminal and the non-inverting terminal of the amplifier respectively, and the differential magnetic flux is output as the detection result of the Hall sensor 20. For convenience of the drawing, the signal processing IC 23 is configured to include the two sensor elements 21 and 22, but actually does not include the two sensor elements 21 and 22. The signal processing IC 23 has wiring connecting the two sensor elements 21 and 22 and an amplifier.

[0044] As described above, the current sensor 100 includes three output busbars 30 and three Hall sensors 20. One output busbar 30 and one Hall sensor 20 together may be referred to as a sensor module 50. The current sensor 100 has three sensor modules 50. The three sensor modules 50 are a U-phase sensor module 50U, a V-phase sensor module 50V, and a W-phase sensor module 50W.

[0045] The U-phase sensor module 50U has a U-phase output busbar 30U and a U-phase Hall sensor 20U. The V-phase sensor module 50V has a V-phase output busbar 30V and a V-phase Hall sensor 20V. The W-phase sensor module 50W has a W-phase output busbar 30W and a W-phase Hall sensor 20W. In each of the Hall sensors 20U, 20V, and 20W, the magnetic flux density of the magnetic field around the corresponding output busbars 30U, 30V, and 30W is detected.

[0046] Hereinafter, elements with the symbol "U" attached are components of the U-phase sensor module 50U. Elements with the symbol "V" attached are components of the V-phase sensor module 50U. Elements with the symbol "W" attached are components of the W-phase sensor module 50U. Note that the output busbars 30U, 30V, and 30W have the same configuration as the output busbar 30 described so far. The Hall sensors 20U, 20V, and 20W have the same configuration as the Hall sensor 20 described so far.

[0047] The current sensor 100 is provided such that three sensor modules 50U, 50V, and 50W are adjacent to each other in the X direction. As an example, the three sensor modules 50U, 50V, and 50W are arranged in order as the U-phase sensor module 50U, the V-phase sensor module 50V, and the W-phase sensor module 50W. The three sensor modules 50U, 50V, and 50W are arranged such that their respective extension parts overlap with each other in the X direction. The first extension part 31 of each of the sensor modules 50U, 50V, and 50W overlaps in the X direction. The second extension part 32 of each of the sensor modules 50U, 50V, and 50W overlaps in the X direction. The third extension part 33 of each of the sensor modules 50U, 50V, and 50W overlaps in the X direction.

[0048] According to this, the magnetic fields generated around the second extension part 32 of each phase are in a parallel relationship with each other. The magnetic fields generated around the second extension part 32 of each phase are both formed along the YZ plane. Therefore, for example, the magnetic flux density of the magnetic field around the second extension part 32V of the V phase to be detected by the V-phase Hall sensor 20V is suppressed from being superimposed by the magnetic flux density of the magnetic field generated around the second extension part 32U of the U phase or the second extension part 32W of the W phase. The same applies to the U-phase Hall sensor 20U and the W-phase Hall sensor 20W. The magnetic field around the detection target part of a predetermined phase to be detected by the Hall sensor 20 of the predetermined phase and the magnetic field around the detection target part of the predetermined phase to be detected by the Hall sensor 20 of another phase are non-interfering with each other. The magnetic flux density of the magnetic field around the detection target part of a predetermined phase to be detected by the Hall sensor 20 of the predetermined phase is suppressed from being superimposed by the magnetic flux density of the magnetic field around the detection target part of another phase.

[0049] The current sensor 100 has a sealing member 60 that seals a part of the three sensor modules 50U, 50V, and 50W. The main material of the sealing member 60 is resin. The sealing member 60 has a substantially rectangular parallelepiped shape with a longitudinal direction in the X direction. The sealing member 60 is provided on the three sensor modules 50U, 50V, and 50W so as to seal the three lower pieces 36 and a part of the three first extension parts 31. The sealing member 60 has an upper surface 60A and a lower surface 60B spaced apart in the Z direction. The upper surface 60A of the sealing member 60 is provided between the upper piece 35 and the lower piece 36 with respect to the Z direction. For this reason, a part of the upper surface 60A of the sealing member 60 is provided inside the through hole 34.

[0050] Also, a sensor substrate 40 is disposed on the upper surface 60A of the sealing member 60. The sensor substrate 40 has a base portion 41 extending in the X direction and three branch portions 42, 43, and 44 extending in the Y direction from the base portion 41. The base portion 41 extends along three second extension portions 32 arranged in a straight line. The base portion 41 is arranged opposite to the three second extension portions 32 with respect to the Y direction. Branch portions 42, 43, and 44 are provided at positions corresponding to the through holes 34 of each phase of the output bus bar 30 in the base portion 41.

[0051] The branch portion 42 extends in the Y direction from the base portion 41 so as to pass through the through hole 34 of the U-phase output bus bar 30U. The U-phase Hall sensor 20U is disposed on the branch portion 42. The branch portion 43 extends in the Y direction from the base portion 41 so as to pass through the through hole 34 of the V-phase output bus bar 30V. The V-phase Hall sensor 20V is disposed on the branch portion 43. The branch portion 44 extends in the Y direction from the base portion 41 so as to pass through the through hole 34 of the W-phase output bus bar 30W. The W-phase Hall sensor 20W is disposed on the branch portion 44.

[0052] Regarding the arrangement of the three sensor modules 50, the arrangement is not limited to a form in which the respective extension portions are arranged in an overlapping manner with respect to the X direction. The arrangement of the three sensor modules 50 may be any arrangement as long as the magnetic flux density of the magnetic field around the detection target portion to be detected by the Hall sensor 20 of a predetermined phase is suppressed from being superimposed on the magnetic flux density of the magnetic field around the detection target portion of another phase. The three second extension portions 32 do not have to overlap with respect to the X direction, and the three second extension portions 32 may be non-overlapping with respect to the Y direction.

[0053] <Function and Effect> The current sensor 100 includes a plurality of sensor modules 50 including an output bus bar 30 and a Hall sensor 20. The output bus bar 30 has a first extension portion 31, a second extension portion 32, and a third extension portion 33. A through hole 34 for passing the Hall sensor 20 in the Y direction is formed in the second extension portion 32. The second extension portion 32 is a detection target portion where the magnetic flux density of the magnetic field is detected by the Hall sensor 20. A plurality of sensor modules 50 are arranged so that the magnetic field around the second extension portion 32 does not interfere. Therefore, the magnetic flux density of the magnetic field around the detection target portion of a predetermined phase to be detected by the Hall sensor 20 of the predetermined phase is suppressed from being superimposed on the magnetic flux density of the magnetic field around the detection target portion of another phase.

[0054] The sensor elements 21 and 22 include a first sensor element 21 and a second sensor element 22 that are spaced apart and arranged in the Y direction. The first sensor element 21 and the second sensor element 22 have a detection surface 25 facing the same direction as each other. The first sensor element 21 and the second sensor element 22 detect the magnetic flux density of the magnetic field around the upper piece 35 and the lower piece 36 input to the detection surface 25. The Hall sensor 20 has a signal processing IC 23. The signal processing IC 23 outputs a signal based on the difference between the magnetic flux density detected by the first sensor element 21 and the magnetic flux density detected by the second sensor element 22. According to this, it becomes possible to increase the magnitude of the magnetic flux density of the magnetic field around the second extension portion 32, which is the object to be detected by the sensor elements 21 and 22.

[0055] Also, as described above, the Hall sensor 20 is passed through the through-hole 34. Therefore, even if the Hall sensor 20 moves up and down in the Z direction, the distance between the Hall sensor 20 and the edge portion that partitions the through-hole 34 in the second extension portion 32 always becomes closer. Even if the position of the Hall sensor 20 in the Z direction moves up and down, the Hall sensor 20 can easily detect the magnetic field generated around the second extension portion 32. Accordingly, the variation in the magnitude of the signal output from the Hall sensor 20 becomes small. The robustness of the detection sensitivity of the Hall sensor 20 is improved. Different from the present embodiment, compare with a form in which the Hall sensor 20 is not passed through the through-hole 34 and the Hall sensor 20 simply overlaps the detection target portion in the Z direction. In the case of this comparative form, when the position of the Hall sensor 20 in the Z direction moves up and down, the variation in the magnitude of the output signal is large. In this respect as well, the present embodiment has an advantageous effect. FIG. 6 shows a graph showing the relationship between the position of the Hall sensor 20 in the Z direction and the magnetic flux density. The solid line is the graph regarding the first embodiment. The dashed line is the graph regarding the comparative form.

[0056] The second extension portion 32 extends along the X direction. The first extension portion 31 extends along the Y direction so as to move away from the second extension portion 32. The third extension portion 33 extends along the Y direction so as to move away from the second extension portion 32. The extension directions of the first extension portion 31 and the third extension portion 33 are different from the extension direction of the second extension portion 32. A plurality of sensor modules 50U, 50V, 50W are arranged so that the second extension portions 32 are arranged along the Y direction. According to this, the magnetic fields generated around the second extension portions 32 of each phase become parallel to each other. The interference between the magnetic fields generated around the second extension portion 32 is effectively suppressed. The pitch with the adjacent sensor module 50 can be narrowed. The current sensor 100 can be miniaturized.

[0057] The Hall sensor 20 is disposed in the through-hole 34. The first extension portion 31 and the third extension portion 33 do not overlap with the Hall sensor 20 in the Z direction. Compared with the case where the first extension portion 31 and the third extension portion 33 overlap with the Hall sensor 20 in the Z direction, current easily flows evenly from the first extension portion 31 to the upper piece 35 and the lower piece 36. Current easily flows evenly from the upper piece 35 and the lower piece 36 to the third extension portion 33. Occurrence of bias in the current flowing through the output bus bar 30 is suppressed.

[0058] The current sensor 100 includes a sealing member 60 that seals a part of the three sensor modules 50, and a sensor substrate 40 disposed in the sealing member 60. The sensor substrate 40 has a base portion 41 extending in the X direction, and branch portions 42, 43, 44 extending in the Y direction from the base portion 41. The branch portions 42, 43, 44 are provided at positions corresponding to the through-hole 34 of the output bus bar 30 in the base portion 41. The branch portions 42, 43, 44 extend in the Y direction from the base portion 41 so as to pass through the through-hole 34. Hall sensors 20 are surface-mounted on the branch portions 42, 43, 44. Different from this embodiment, productivity is improved as compared with a form in which the sensor substrate 40 is through-hole mounted side by side with the Hall sensor 20 in the penetrating direction of the through-hole 34. (Second Embodiment)

[0059] In the first embodiment, the form in which the through-hole 34 is rectangular in a plan view in the Y direction has been described. However, the shape of the through-hole 34 is not limited to a rectangle. In the second embodiment, the shape of the through-hole 234 is different from a rectangle in a plan view in the Y direction. In the second embodiment, two of the four corners of the rectangle are curved. In the second embodiment, the through-hole 234 has a width in the X direction and has four corners 237A, 237B, 237C, 27D. The positions of the four corners 237A, 237B, 237C, 237D are the same as the positions of the four corners 37A, 37B, 37C, 37D of the first embodiment. In the second embodiment, the corners 237B and 237D of the through-hole 234 are curved. The corner 237A and the corner 237C are formed at right angles. Note that the corner 237C may be referred to as the first corner. The corner 237A may be referred to as the second corner.

[0060] In the second embodiment, the projection area in the Y direction in the through hole 234 and the projection areas in the Z direction in the first extension part 31 and the third extension part 33 overlap. In a plan view in the Y direction, a part of the first extension part 31 overlaps with the corner 237C in the Z direction. The corner 237C is formed at a right angle. Different from the second embodiment, in the comparative form shown in FIG. 8, the corner 237C is formed in a curved shape. In the comparative form, current flows in the direction indicated by the arrow at a part on one end side of the second extension part 32. At a part on one end side of the second extension part 32, a magnetic field is formed in the circumferential direction surrounding the current flow direction.

[0061] Due to this magnetic field, a magnetic field from the Hall sensor 20 toward the sensor substrate 40 is input to the first sensor element 21. A magnetic field from the sensor substrate 40 toward the Hall sensor 20 is input to the second sensor element 22. Also, as shown in FIG. 9, a magnetic field from the sensor substrate 40 toward the Hall sensor 20 is input to the first sensor element 21 by the upper piece 35 and the lower piece 36. A magnetic field from the Hall sensor 20 toward the sensor substrate 40 is input to the second sensor element 22 by the upper piece 35 and the lower piece 36. In the comparative form, the magnetic flux density of the magnetic field around the upper piece 35 and the lower piece 36 input to the first sensor element 21 is weakened. The magnetic flux density of the magnetic field around the upper piece 35 and the lower piece 36 input to the second sensor element 22 is weakened.

[0062] On the other hand, in the second embodiment, since the corner 237C is formed at a right angle, current flows in the direction indicated by the arrow shown in FIG. 7 at a part on one end side of the second extension part 32. At a part on one end side of the second extension part 32, a magnetic field is formed in the circumferential direction surrounding the current flow direction. In the second embodiment, the direction of this magnetic field is different from the direction of the magnetic field formed around the upper piece 35 and the lower piece 36. Therefore, it is possible to suppress the magnetic field formed around the part on one end side of the second extension part 32 from overlapping with the magnetic field formed around the upper piece 35 and the lower piece 36. It is possible to suppress the magnetic flux density of the magnetic field around the upper piece 35 and the lower piece 36 input to the first sensor element 21 from being weakened. It is possible to suppress the magnetic flux density of the magnetic field around the upper piece 35 and the lower piece 36 input to the second sensor element 22 from being weakened.

[0063] Also, in the second embodiment, in addition to the corner 237C, the corner 237A is also formed at a right angle. In a plan view in the Y direction, the corner 237A and the third extension 33 overlap in the Z direction. Since the corner 237A is formed at a right angle, the direction of the magnetic field formed around the current flowing through the corner 237A can be made different from the direction of the magnetic field formed around the current flowing through the upper piece 35 and the lower piece 36. It is possible to suppress the magnetic field formed around the current flowing through the corner 237A from overlapping with the magnetic field formed around the current flowing through the upper piece 35 and the lower piece 36.

[0064] In the second embodiment, it is suppressed that the magnetic field formed around the current flowing through the upper piece 35 and the lower piece 36 input to the first sensor element 21 is weakened. It is suppressed that the magnetic field formed around the current flowing through the upper piece 35 and the lower piece 36 input to the second sensor element 22 is weakened. (Third Embodiment)

[0065] FIG. 10 is a perspective view of the sensor module 50 in the third embodiment. FIG. 11 is a cross-sectional view taken along the cross-section shown in FIG. 10. In the third embodiment, the shape of the through hole 334 is different from a rectangle in a plan view in the Y direction. The through hole 334 is formed in an elliptical shape in a plan view in the Y direction. In the third embodiment, the through hole 234 has a width in the X direction and has four corners 337A, 337B, 337C, and 337D. The positions of the four corners 337A, 337B, 337C, and 337D are the same as the positions of the four corners 37A, 37B, 37C, and 37D in the first embodiment. In the third embodiment, the projection area in the Y direction of the through hole 334 and the projection area in the Z direction of the first extension 31 and the third extension 33 do not overlap. Note that the corner 337C may be referred to as the first corner. The corner 337A may be referred to as the second corner.

[0066] In the third embodiment, four corners 337A, 337B, 337C, and 337D are formed to be curved. In a view from the Y direction plane, the corner 337C and the first extension 31 do not overlap with respect to the Z direction. In a view from the Y direction plane, the corner 337A and the third extension 33 do not overlap with respect to the Z direction. The corner 337C is the closest to the first extension 31 among the four corners 337. The corner 337C is curved so as to move away from the first extension 31. The corner 337A is curved so as to move away from the third extension 33.

[0067] In the third embodiment, the corners 337A and 337C are formed to be curved. In the third embodiment, current flows in the direction indicated by the arrow at a site on one end side of the second extension 32. Around the current flowing through the site on one end side and the site on the other end side of the second extension 32, a magnetic field is formed in the circumferential direction surrounding the current flow direction. Due to this magnetic field, as shown in FIG. 12, a magnetic field from the sensor substrate 40 toward the Hall sensor 20 is input to the first sensor element 21. A magnetic field from the Hall sensor 20 toward the sensor substrate 40 is input to the second sensor element 22. Further, a magnetic field from the sensor substrate 40 toward the Hall sensor 20, which is formed around the current flowing through the upper piece 35 and the lower piece 36, is input to the first sensor element 21. A magnetic field from the Hall sensor 20 toward the sensor substrate 40, which is formed around the current flowing through the upper piece 35 and the lower piece 36, is input to the second sensor element 22.

[0068] According to this, the magnetic flux density of the magnetic field around the upper piece 35 and the lower piece 36 input to the first sensor element 21 increases. The magnetic flux density of the magnetic field around the upper piece 35 and the lower piece 36 input to the second sensor element 22 increases. The magnitude of the signal output from the Hall sensor 20 can be increased. The sensitivity of the Hall sensor 20 can be improved. (Fourth Embodiment)

[0069] In the first embodiment, the form in which the thickness direction of the second extension portion 32 is the Y direction has been described. However, the thickness direction of the second extension portion 32 is not limited to the Y direction. As shown in FIG. 12, in the fourth embodiment, the thickness direction of the second extension portion 32 is the Z direction. In the fourth embodiment, the first extension portion 31, the second extension portion 32, and the third extension portion 33 are flush in the XY plane. Thus, the same effects as those of the first embodiment can be achieved. (Fifth Embodiment)

[0070] In the first embodiment, the form in which the first extension portion 31 is closest to the corner 37C and the third extension portion 33 is closest to the corner 37A has been described. However, the arrangements of the first extension portion 31 and the third extension portion 33 are not limited thereto. As shown in FIG. 13, in the fifth embodiment, the first extension portion 31 is closest to the corner 37C and the third extension portion 33 is closest to the corner 37D. Thus, the same effects as those of the first embodiment can be achieved.

Description of Reference Numerals

[0071] 20 Hall sensor, 21 first sensor element, 22 second sensor element, 23 signal processing IC, 25 detection surface, 30 bus bar, 31 first extension portion, 32 second extension portion, 32A first surface, 32B second surface, 33 third extension portion, 34 through hole, 35 upper piece, 36 lower piece, 40 sensor substrate, 41 base portion, 42, 43, 44 branch portions, 50 sensor module, 100 current sensor, 237A, 237C, 337A, 337C corners, Y thickness direction, Z up and down direction.

Claims

1. A current sensor (100) comprising a plurality of sensor modules (50) each having a bus bar (30) through which current flows and a Hall sensor (20) including sensor elements (21, 22) for detecting a magnetic field generated around the bus bar, The bus bar has a detection target portion (32) which is a target for detecting the magnetic field, an inflow portion (31) connected to the detection target portion on the inflow side of the current with respect to the detection target portion, and an outflow portion (33) connected to the detection target portion on the outflow side of the current with respect to the detection target portion, The detection target portion has a through hole (34) through which the Hall sensor passes in its plate thickness direction (Y), A current sensor in which a plurality of the sensor modules are arranged such that the magnetic fields generated around the detection target portion do not interfere with each other.

2. The detection target portion has an upper piece (35) and a lower piece (36) arranged in the vertical direction (Z) via the through hole, The sensor elements have a first sensor element (21) and a second sensor element (22) spaced apart in the plate thickness direction via the detection target portion, The first sensor element and the second sensor element have a detection surface (25) facing the same direction in the vertical direction, and detect the magnetic fields around the upper piece and the lower piece input to the detection surface, The Hall sensor further has an output portion (23) that outputs a signal based on a difference between the magnetic flux density of the magnetic field detected by the first sensor element and the magnetic flux density of the magnetic field detected by the second sensor element. The current sensor according to claim 1.

3. A first extension direction in which the inflow portion extends away from the detection target portion and a third extension direction in which the outflow portion extends away from the detection target portion are different from a second extension direction in which the detection target portion extends so as to connect the inflow portion and the outflow portion, The current sensor according to claim 2, wherein a plurality of the sensor modules are arranged such that the detection target portions are arranged along the second extension direction.

4. The detection target part has a first surface (32A) and a second surface (32B) spaced apart in the plate thickness direction, A part of the inflow part is connected to the first surface, A part of the outflow part is connected to the second surface, The inflow part and the outflow part are provided on opposite sides via the through hole with respect to the second extension direction, The current sensor according to claim 3, wherein the inflow part and the outflow part do not overlap with the Hall sensor in the vertical direction.

5. The through hole has a width in the second extension direction and has four corners (237A, 237B, 237C, 237D), When viewed from the plate thickness direction, the inflow part and one of the four corners closest to the inflow part overlap in the vertical direction, The current sensor according to claim 4, wherein one of the four corners closest to the inflow part is a right angle.

6. Of the four corners, a second corner (237A) different from the first corner (237C) which is the one closest to the inflow part overlaps with the outflow part in the vertical direction when viewed from the plate thickness direction, The current sensor according to claim 5, wherein the second corner is a right angle.

7. The through hole has a width in the second extension direction and has four corners (337A, 337B, 337C, 337D), When viewed from the plate thickness direction, the inflow part and the outflow part do not overlap with the through hole in the vertical direction, The first corner (337C) which is the one closest to the inflow part among the four corners curves so as to move away from the inflow part, The current sensor according to claim 4, wherein the second corner (337A) which is the one closest to the outflow part among the four corners curves so as to move away from the outflow part.

8. The current sensor further includes a substrate (40) on which the Hall sensor is mounted, The substrate has a base portion (41) that extends in the second extension direction while facing the plurality of detection target portions in the plate thickness direction, and a plurality of branch portions (42, 43, 44) that pass through the through holes formed in each of the plurality of detection target portions. The current sensor according to any one of claims 3 to 7, wherein the hall sensor is mounted on each of the branch portions.

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