JP6914671B2 - Current sensor - Google Patents

Description

The present invention relates to a current sensor.

A current sensor that detects the amount of current using a magnetic sensor is known. For example, Patent Document 1 includes a bus bar through which a current flows and a sensor element arranged on the bus bar, and the bus bar has a pair of slits formed on an arc line extending outward with the sensor element in between. It is disclosed. In this current sensor, the current flows in the bus bar so as to draw an arc around the sensor element, so that the decrease in measurement accuracy due to the rotation of the sensor element on the bus bar is suppressed. Further, in Patent Document 2, a circuit board having an insulating substrate and a bus bar as a main path superimposed on the insulating substrate, and a current dividing path via a resistance element in parallel with the main path are provided on the insulating substrate from the main path. A circuit configuration including a current sensor for detecting a diverted current is disclosed. In this circuit configuration, the current shunted by the resistance element is smaller than the current in the main path. Therefore, by detecting the shunt current with a current sensor with a small capacitance, the large current flowing in the main path is calculated with a small resistance loss. It becomes possible to do.
Patent Document 1 Japanese Patent Application Laid-Open No. 2016-70904 Patent Document 2 Japanese Patent Application Laid-Open No. 2016-1350339

An object of the present invention is to provide a current sensor capable of detecting a large current.

In one aspect of the present invention, a conductor plate through which the current to be measured flows and one surface of the conductor plate along a path including a section extending from one side in the uniaxial direction to the other side and changing the direction in which the current flows at least in a part. A current sensor comprising a substrate fixed on the substrate and a magnetic sensor provided at a position corresponding to a section on the substrate and detecting a magnetic field generated by a current flowing through the section is provided.

The outline of the above invention does not list all the features of the present invention. Sub-combinations of these feature groups can also be inventions.

The configuration of the current sensor according to this embodiment is shown in a top view. The internal configuration of the current sensor with respect to the reference line BB of FIG. 1A is shown. The arrangement of slits on the busbar and the arrangement of deflection sections in the current path are shown. Indicates a state in which the current sensor is connected to an external device. The connection state of the current sensor is shown in the cross section of FIG. 3A with respect to the reference line BB. The configuration of the bus bar formed by one step in the manufacturing process of the current sensor is shown in a top view. The cross section of the bus bar about the reference line BB of FIG. 4A is shown. A top view shows a state in which the substrate is provided on the upper surface of the bus bar by one step in the manufacturing process of the current sensor. The cross section of the bus bar and the substrate about the reference line BB of FIG. 5A is shown. The state in which the package is mounted on the substrate by one step in the manufacturing process of the current sensor is shown in a top view. A cross section of a bus bar, a substrate, and a package with respect to the reference line BB of FIG. 6A is shown. Another example of the magnetic material in the current sensor according to this embodiment is shown. Further, another type of magnetic material in the current sensor according to the present embodiment is shown. The configuration of the current sensor according to the modified example is shown in a top view. The internal configuration of the current sensor with respect to the reference line BB of FIG. 8A is shown. The arrangement of slits on the bus bar and the arrangement of deflection sections in the current path in the current sensor according to the modified example are shown.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the inventions that fall within the scope of the claims. Also, not all combinations of features described in the embodiments are essential to the means of solving the invention.

1A and 1B show the configuration of the current sensor 1 according to the present embodiment. Here, FIG. 1A shows the configuration of the current sensor 1 in a top view, and FIG. 1B shows the internal configuration of the current sensor 1 with respect to the reference line BB of FIG. 1A. The vertical direction in FIG. 1A is the vertical direction, the horizontal direction in FIGS. 1A and 1B is the horizontal direction, and the vertical direction in FIG. 1B is the height direction. Further, viewing the height direction from top to bottom is called top view. The current sensor 1 is a sensor that detects the magnitude (or the amount of current) of a current (also referred to as a measured current) using a magnetic sensor, and has an object of detecting a large current of several hundred A or more, for example. do. The current sensor 1 is connected between the output terminals of an external device (not shown) and is configured to measure the current to be measured flowing between them. The bus bar 2, the substrate 3, the magnetic sensor elements 4a and 4b, and the signal processing IC 4c , Package 4, magnetic materials 5, 6 and insulating members 7, 8.

The bus bar 2 is an example of a conductor plate through which a current to be measured flows. Here, the current to be measured flows along a path (also referred to as a current path) L1 extending from one side in the lateral direction to the other side on the bus bar 2 and connecting between two openings 2d described later. In the present embodiment, as an example, the current to be measured is a direct current flowing on the bus bar 2 from the left side to the right side in the horizontal direction. The bus bar 2 has a thickness (for example, 1.0 mm or more) larger than that of the substrate 3 described later in order to pass a large current, and in order to efficiently release the heat generated by the flow of the current, for example, copper, aluminum, etc. It is formed into a plate having a large surface using a metal having a high thermal conductivity. As an example, the bus bar 2 is formed in a rectangular shape having a longitudinal direction in the lateral direction, including an opening 2d and slits 2a and 2b.

One opening 2d is formed at both ends of the bus bar 2 in the horizontal direction, and one opening 2d is formed in the center in the vertical direction. In the present embodiment, as an example, the opening 2d has a circular shape, and as will be described later, by passing the fixture 9 through the opening 2d of the bus bar 2, the current sensor 1 is connected to the output terminal of the external device that outputs the current to be measured. Can be fixed.

The slits 2a and 2b are examples of at least one slit formed in the bus bar 2, whereby a section in which the direction in which the current flows changes in at least a part of the current path L1 extending in the lateral direction on the bus bar 2 (with a deflection section). (Call) La and Lb are provided. The slits 2a and 2b include two slits each, and extend in a direction in which at least the tip side portions intersect in the lateral direction from the lower and upper outer edges in the vertical direction of the bus bar 2, respectively. As a result, deflection sections La and Lb are formed around one of the two slits 2a and 2b, respectively, and the surface area of the bus bar 2 is increased to maintain heat dissipation while directing the current path L1 to a direction other than the lateral direction. be able to. That is, the current to be measured can flow in the bus bar 2 in a direction other than the lateral direction. Details of the arrangement of the slits 2a and 2b on the bus bar 2 and the arrangement of the deflection sections La and Lb in the current path L1 will be described later.

In the present embodiment, the direction of intersection in the horizontal direction is the vertical direction orthogonal to the horizontal direction, but the direction is not limited to this and may be any direction that intersects in the horizontal direction. Further, for each of the two slits 2a and 2b, the direction in which they intersect in the horizontal direction may be the vertical direction, or may be any direction other than the lateral directions different from each other.

The substrate 3 is a thin plate or sheet-like member that supports the package 4 containing the magnetic sensor elements 4a and 4b and the signal processing IC 4c on the bus bar 2. In the present embodiment, as an example, a flexible printed wiring board having a thickness of 500 μm or less. Adopt a board. The substrate 3 is fixed on one surface (that is, the upper surface) of the bus bar 2 by being attached via an adhesive layer or the like. Since the substrate 3 is thin, those magnetically sensitive parts of the magnetic sensor elements 4a and 4b can be fixed on the upper surface in close proximity to the bus bar 2, whereby the current to be measured flows in the bus bar 2. The magnetic field to be generated can be more focused on the magnetically sensitive portions of the magnetic sensor elements 4a and 4b and can be detected efficiently. The substrate 3 has a main body portion 3a and a stretched portion 3b.

The main body 3a is a portion that supports the package 4, and a wiring pattern (not shown) for transmitting the input / output signals of the package 4 is formed on the upper surface thereof. In the present embodiment, as an example, the main body 3a is formed into a rectangular shape having a width smaller than that of the bus bar 2 in the vertical direction and a width smaller than the separation distance between the two openings 2d in the horizontal direction. Therefore, the substrate 3 covers at least a part of the slits 2a and 2b formed in the bus bar 2, particularly the upper part on the tip end side, by the main body portion 3a.

The extending portion 3b is a portion in which a wiring pattern extending from the main body portion 3a is provided and extends out of the current sensor 1, and as an example, the extending portion 3b extends from the upper right end portion of the main body portion 3a to the upper side of the drawing. The stretched portion 3b has a rectangular shape having a longitudinal direction, and has a length larger than half of the difference between the width of the bus bar 2 and the width of the main body portion 3a in the vertical direction. Therefore, the substrate 3 is stretched out of the stretched portion 3b (excluding the base end connected to the main body portion 3a) without being fixed to the upper surface of the bus bar 2. As a result, an external device on which the current sensor 1 mounts the input / output signals of the package 4 supported on the main body 3a via the wiring pattern provided in the extension 3b extending from the main body 3a to the outside of the bus bar 2. Can be transmitted to.

The wiring pattern provided on the upper surface of the substrate 3 is insulated from the bus bar 2 by molding the substrate 3 from an insulating member, providing an insulating member 7 described later between the substrate 3 and the bus bar 2.

The magnetic sensor elements 4a and 4b are examples of magnetic sensors, and are sensors that detect a magnetic field generated by a current flowing in the bus bar 2. As the magnetic sensor elements 4a and 4b, for example, a compound semiconductor Hall element composed of InAs, GaAs, etc., a Hall element composed of silicon (or a Hall IC integrated with an amplification circuit), and a magnetic resistance element are adopted. be able to. The magnetic sensor elements 4a and 4b output a voltage corresponding to the strength of the detected magnetic field as an output signal to the signal processing IC 4c described later. The magnetic sensor elements 4a and 4b and the signal processing IC 4c described later may be formed on the same silicon substrate. As a result, wiring by wire bond between the magnetic sensor elements 4a and 4b and the signal processing IC 4c becomes unnecessary, and improvement in reliability can be expected.

The magnetic sensor elements 4a and 4b are provided at positions on the substrate 3 corresponding to the deflection sections La and Lb, respectively. Here, the positions corresponding to the deflection sections La and Lb are the positions inside the deflection sections La and Lb in which the direction of the current path L1 changes in the top view. In the present embodiment, the deflection sections La and Lb are used as an example. The positions are located inside the tips of the slits 2a and 2b to be formed, respectively. As a result, when the current to be measured flows in the bus bar 2 along the current path L1, the magnetic field directed in the direction perpendicular to one surface of the bus bar 2 (that is, the height direction) is generated by the current flowing in the deflection sections La and Lb. The magnitude of the current to be measured is measured by detecting these magnetic fields generated on one surface of the bus bar 2 via the substrate 3 by magnetic sensor elements 4a and 4b provided inside the deflection sections La and Lb, respectively. can do.

The magnetic sensor elements 4a and 4b are sealed in a package 4 described later, and one surface of the package 4 (that is, that is, the element surface opposite to the magnetic sensitive portion (that is, the portion that detects the magnetic field) is opposed to the substrate 3) is sealed. It is exposed on the bottom). When the package 4 is mounted on the substrate 3, the magnetically sensitive portions of the magnetic sensor elements 4a and 4b are close to the bus bar 2, whereby the magnetic field generated by the current to be measured flowing in the bus bar 2 is generated by the magnetic sensor elements 4a and 4b. It is possible to focus more on the magnetically sensitive portion of the magnet and detect it with a high SN ratio.

The signal processing IC 4c applies a bias to the magnetic sensor elements 4a and 4b, processes the output signals from the magnetic sensor elements 4a and 4b, and flows in the bus bar 2 along the current path L1. Is a device that calculates. The calculation result is output to an external device or the like via the wiring pattern on the substrate 3. The signal processing IC 4c calculates the difference between the memory, the sensitivity correction circuit, the offset correction circuit for correcting the output offset, the amplifier circuit for amplifying the output signals from the magnetic sensor elements 4a and 4c, and the output signals of the magnetic sensor elements 4a and 4b. At least one of a difference calculation circuit, a temperature correction circuit that corrects the output according to the temperature, and the like may be built in.

In the present embodiment, the signal processing IC 4c is configured as a device separate from the magnetic sensor elements 4a and 4b, is connected to the magnetic sensor elements 4a and 4b by wire bonding, for example, and is sealed together with them in a package 4 described later. There is. As a result, the signal processing IC 4c is placed at the same temperature as the magnetic sensor elements 4a and 4b, so that the temperature correction circuit of the signal processing IC 4c accurately corrects the output signals of the magnetic sensor elements 4a and 4b according to the temperature. Is possible.

The package 4 is a member that seals and protects the magnetic sensor elements 4a and 4b and the signal processing IC 4c inside. The package 4 is molded into a rectangular parallelepiped shape having a thickness smaller than one side of a rectangular shape (that is, the upper surface) and one side of the upper surface by molding using, for example, a molding material such as a resin having excellent insulating properties such as epoxy. It is molded. In the present embodiment, as an example, in the package 4, the magnetic sensor elements 4a and 4b are placed on one side (that is, the left side of the drawing) and the other side (that is, the right side of the drawing) in the lateral direction, respectively, and the signal processing IC 4c is located between them. Have been placed.

Package 4 is, for example, a leadless package. In the package 4, a dicing tape is provided in the gap between the lead frames, the magnetic sensor elements 4a and 4b are placed on the dicing tape with the magnetically sensitive portion facing upward, the signal processing IC 4c is placed on the lead frame, and the magnetic sensor elements 4a and 4b are placed. Is manufactured by connecting the signal processing IC 4c and the lead frame by wire bonding, sealing them with a molding material, dicing them to an appropriate size and shape, and peeling off the dicing tape. As a result, the back surfaces of the magnetic sensor elements 4a and 4b are exposed flush with the lower surface of the package 4, and at least a part of the lead frame is flush with the lower surface of the package 4 as terminals for connecting to the input / output signals of the signal processing IC 4c. By connecting the terminals of the package 4 to the wiring on the board 3 and mounting the package 4 on the bus bar 2 via the board 3, the magnetic sensor elements 4a and 4b are attached to the bus bar 2. Can be close.

The magnetic materials 5 and 6 are materials for efficiently focusing the magnetic field generated by the current to be measured flowing in the bus bar 2 on the magnetically sensitive portions of the magnetic sensor elements 4a and 4b. In the present embodiment, as the magnetic materials 5 and 6, those formed by using, for example, manganese (Mn-Zn) -based or nickel (Ni-Zn) -based ferrite are used. The magnetic material 5 is formed into a rectangular plate having an area smaller than the upper surface of the package 4, and is on the other surface (that is, the upper surface) side of the package 4 facing the substrate 3 from one surface (that is, the lower surface) of the magnetic sensor element 4a. , 4b are arranged to face each other. Further, the magnetic material 6 is formed into a rectangular plate shape like the magnetic material 5, and is arranged on the lower surface side of the bus bar 2 so as to face the magnetic sensor elements 4a and 4b.

The magnetic materials 5 and 6 are all formed into one large rectangular shape including the upper surface or the lower surface of each of the magnetic sensor elements 4a and 4b in the package 4, and are arranged so as to cover both the upper surface or the lower surface. However, the present invention is not limited to this, and the magnetic sensor elements 4a and 4b may be formed into a plurality of rectangular shapes including the upper surface or the lower surface thereof, and may be arranged so as to individually cover the upper surface or the lower surface of each. .. Further, the magnetic materials 5 and 6 may be formed into a size and shape so that the magnetic field focused on the magnetically sensitive portions of the magnetic sensor elements 4a and 4b is not saturated, or when the magnetic field is sufficiently focused. It is not necessary to provide at least one of the magnetic materials 5 and 6.

The insulating member 7 is an insulating member for increasing the withstand voltage between the bus bar 2 and the substrate 3. In the present embodiment, the insulating member 7 is formed into a sheet using, for example, polyimide. The insulating member 7 improves the dielectric strength of the magnetic sensor elements 4a, 4b and the like provided on the substrate 3 against the bus bar 2.

The insulating member 8 is an insulating member provided between the bus bar 2 and the magnetic material 6. In the present embodiment, the insulating member 8 is formed into a sheet using polyimide as an example. The insulating member 8 allows the current to be measured to flow along the current path L1 in the bus bar 2 without causing a short circuit, particularly when the magnetic material 6 is a conductor.

FIG. 2 shows the details of the arrangement of the slits 2a and 2b on the bus bar 2 and the arrangement of the deflection sections La and Lb in the current path L1. As described above, the slits 2a and 2b include two slits each. The two slits 2a and 2b are arranged alternately in the horizontal direction, respectively, in the vertical direction from different outer edges (that is, lower and upper outer edges) of the bus bar 2 in the vertical direction toward the inside (that is, the deflection sections La and Lb). It is formed by extending to.

Each of the two slits 2a and 2b has a length larger than half the vertical width of the bus bar 2, and the two slits 2a form a straight line L0 connecting the two openings 2d formed at both ends of the bus bar 2. The two slits 2b extend from the lower side to the upper side of the drawing and extend the straight line L0 from the upper side to the lower side of the drawing. As a result, the current path L1 meanders on the bus bar 2 while avoiding the tips of the two slits 2a and 2b, respectively, and connects the two openings 2d. That is, the current path L1 turns from the lower side to the upper side of the straight line L0 from the opening 2d on the left side of the drawing, avoiding the tip of the slit 2b on the left side, and from the upper side to the lower side of the straight line L0 avoiding the tip of the slit 2a on the left side. Turn to the side, avoid the tip of the slit 2b on the right side and turn from the bottom to the top of the straight line L0, and avoid the tip of the slit 2a on the right side and turn to reach the opening 2d on the right side. Here, the slit 2a on the left side forms a deflection section La that changes its direction downward in the vertical direction around the tip thereof. Further, the slit 2b on the right side forms a deflection section La that changes the direction in the vertical direction upward around the tip thereof.

As described above, the two slits 2a and 2b extending inward from the different outer edges of the bus bar 2 are arranged alternately in the horizontal direction on the bus bar 2, and the tips of the slits cross the straight line connecting the two openings 2d. The two deflection sections La and Lb are arranged side by side in the horizontal direction and are included in series in the current path L1. Therefore, when the current to be measured flows in the bus bar 2 along the current path L1 from the left opening 2d to the right opening 2d, it flows through the two deflection sections La and Lb included in series in the current path L1, respectively. , A magnetic field with a strength corresponding to the amount of current to be measured is generated inside each section.

At this time, since the two deflection sections La and Lb change the directions of the current paths L1 in different directions, the current to be measured flows clockwise in the deflection section La when viewed from above, so that the current flows inside the deflection section La with respect to the upper surface of the bus bar 2. A downward magnetic field is generated in the vertical direction, that is, in the height direction, and flows counterclockwise in the deflection section Lb when viewed from above, so that an upward magnetic field is generated in the height direction inside the deflection section Lb. Therefore, the magnetic sensor elements 4a and 4b provided on the upper surface of the bus bar 2 via the substrate 3 detect the magnetic fields in opposite directions generated inside the deflection sections La and Lb, respectively, and the signal processing IC 4c detects the magnetic field elements in opposite directions. By calculating the difference between the output signals of 4a and 4b, the noise derived from the external magnetic field entering from outside the current sensor 1 is canceled out, and compared with the case where only one of the output signals of the magnetic sensor elements 4a and 4b is used. The magnitude of the current to be measured can be measured with about twice the sensitivity. Since the current sensor 1 has about twice the sensitivity, it can measure a relatively small current to be measured.

In the current sensor 1 according to the present embodiment, since the two openings 2d to which the current path L1 is connected are formed in the center of the bus bar 2 in the vertical direction, the two slits 2a and 2b are the vertical directions of the bus bar 2. Although it is decided to have a length larger than half of the width in the direction, the two openings 2d may be formed at arbitrary positions in the vertical direction on the bus bar 2, and correspondingly, the slits 2a and 2b may be formed. May have a sum larger than the vertical width of the bus bar 2 and each tip having a length exceeding the straight line L0. As a result, the current path L1 meanders on the bus bar 2 while avoiding the tips of the two slits 2a and 2b, and the deflection sections La and Lb that change their vertical directions in different directions are arranged in the horizontal direction. Including, it connects between the two openings 2d.

In the current sensor 1 according to the present embodiment, the two slits 2a and 2b extending inward from the different outer edges of the bus bar 2 are alternately arranged in the horizontal direction on the bus bar 2 to change their orientations in different directions2. Two deflection sections La and Lb were provided. Here, by arranging the tip of the left slit 2a extending inward from the lower outer edge of the bus bar 2 between the tips of the two slits 2b extending inward from the upper outer edge of the bus bar 2, the tip of the left slit 2a extending inward from the lower outer edge of the bus bar 2 is arranged around the tip of the slit 2a. The formed deflection section La changes its direction with a small curvature. Similarly, by arranging the tip of the right slit 2b extending inward from the upper outer edge of the bus bar 2 between the tips of the two slits 2a extending inward from the lower outer edge of the bus bar 2, the tip of the slit 2b extends around the tip of the slit 2b. The formed deflection section Lb changes its direction with a small curvature. As a result, when the current to be measured flows in the deflection sections La and Lb, a strong magnetic field is generated inside them.

By adjusting the lateral separation distance of each of the two slits 2a and 2b, the strength of the magnetic field detected by the magnetic sensor elements 4a and 4b can be adjusted, and the detection sensitivity of the measured current can be adjusted. good. For example, in order to strengthen the magnetic field detected by the magnetic sensor elements 4a and 4b and improve the detection sensitivity, the lateral separation distances of the two slits 2a and 2b are reduced to reduce the curvatures of the deflection sections La and Lb. May be reduced. Further, in order to weaken the magnetic field detected by the magnetic sensor elements 4a and 4b and avoid saturation of the detection sensitivity, the lateral separation distances of the two slits 2a and 2b are increased to increase the deflection sections La and Lb. The curvature of may be increased. Further, the length and width of the two slits 2a and 2b may be adjusted instead of or in combination with adjusting the lateral separation distances of the two slits 2a and 2b.

In the current sensor 1 according to the present embodiment, the two slits 2a and 2b are arranged alternately in the horizontal direction on the bus bar 2 to form two deflection sections La and Lb arranged in the horizontal direction. The two slits 2b and the slits 2a having the tips arranged between the tips thereof may be arranged alternately in the horizontal direction on the bus bar 2 to form only one deflection section La, or the two slits 2a and their tips may be formed. Only one deflection section Lb may be formed by alternately arranging the slits 2b for arranging the tips between the tips in the horizontal direction on the bus bar 2, or the tips may be formed between the two slits 2b and their tips. The slits 2a to be arranged are arranged alternately in the horizontal direction on the bus bar 2, and another two slits 2a and another slit 2b in which the tip is arranged between the tips thereof are arranged alternately in the horizontal direction on the bus bar 2. May form two deflection sections La and Lb.

3A and 3B show a state in which the current sensor 1 is connected to the output terminal 10 of an external device (not shown). Here, FIG. 3A shows the connected state of the current sensor 1 in a top view, and FIG. 3B shows the connected state of the current sensor 1 in the cross section with respect to the reference line BB of FIG. 3A. The external device is a device capable of passing a relatively large current such as an in-vehicle device or an industrial machine, and a current to be measured is passed between the two output terminals 10. The two output terminals 10 are formed of a metal such as copper or aluminum into a plate shape having one opening 10d at the center of the tips facing each other.

The current sensor 1 can be fixed to an external device by using the fixture 9. In this embodiment, two sets of bolts and nuts are used as the fixture 9. The current sensor 1 is arranged by arranging the substrate 3 on which the package 4 or the like is mounted between the two output terminals 10, and both ends of the bus bar 2 are brought into contact with the two output terminals 10 from below. As a result, the two openings 2d of the bus bar 2 communicate with the openings 10d of the two output terminals 10, respectively. Then, nuts are inserted into the openings 10d of the two output terminals 10 from above, and passed through the nuts arranged below the two openings 2d of the bus bar 2. As a result, the current sensor 1 is fixed between the two output terminals 10.

A method of manufacturing the current sensor 1 according to the present embodiment will be described.

First, as shown in FIGS. 4A and 4B, the conductor plate is processed by a method such as press working, etching, or shaving to form the bus bar 2. Here, the bus bar 2 has a rectangular shape having a longitudinal direction in the horizontal direction, one opening 2d at each end in the horizontal direction, and two each extending in the vertical direction from the lower and upper outer edges in the vertical direction to the inside. Includes two slits 2a, 2b.

Next, as shown in FIGS. 5A and 5B, the substrate 3 is fixed on one surface (that is, the upper surface) of the bus bar 2 via the insulating member 7. The substrate 3 and the insulating member 7 can be attached to the upper surface of the bus bar 2 via an adhesive layer or the like. Here, the main body portion 3a constituting the substrate 3 covers at least a part of the slits 2a and 2b formed in the bus bar 2, particularly above the tip end side portion, and the extending portion 3b is a base connected to the main body portion 3a. Except for the end, it protrudes out of the bus bar 2 without being fixed to the upper surface. If sufficient insulating properties can be obtained only with the substrate 3, the insulating member 7 may not be provided.

Next, as shown in FIGS. 6A and 6B, the package 4 in which the magnetic sensor elements 4a and 4b and the signal processing IC 4c are sealed inside is mounted on the substrate 3. As a result, the magnetic sensor elements 4a and 4b are inside the deflection sections La and Lb included in the current path L1, respectively, and the substrate 3 corresponding to the inside of the tips of the slits 2a and 2b forming the deflection sections La and Lb, respectively. It is placed in the upper position.

Finally, when it is necessary to further increase the sensitivity of the current sensor 1, as shown in FIGS. 1A and 1B, the magnetic material 5 is placed on the upper surface of the package 4 so as to cover the upper surfaces of the magnetic sensor elements 4a and 4b in a plan view. The magnetic material 6 is arranged on the lower surface of the bus bar 2 via the insulating member 8 so as to cover the lower surfaces of the magnetic sensor elements 4a and 4b in a plan view. As a result, the current sensor 1 is completed.

In the current sensor 1 according to the present embodiment, the magnetic material 6 is formed into a rectangular plate shape and arranged on the lower surface side of the bus bar 2 so as to face the magnetic sensor elements 4a and 4b. , The magnetic material may be provided in the slits 2a and 2b formed in the bus bar 2.

FIG. 7A shows another example of the magnetic material 6 in the current sensor 1 according to the present embodiment, that is, the magnetic materials 6a and 6b. The magnetic materials 6a and 6b are embedded in the space at the tip of the left slit 2a and the right slit 2b of the two slits 2a and 2b formed in the bus bar 2, respectively, and supported on the substrate 3. It is arranged so as to face the magnetic sensor elements 4a and 4b. Since the magnetic materials 6a and 6b are embedded in the slits 2a and 2b of the bus bar 2, a non-conductive material, for example, a material formed by using a nickel-based ferrite having a large resistance is used. As a result, the magnetic field generated by the current to be measured flowing in the bus bar 2 is focused on the magnetic sensitive portions of the magnetic sensor elements 4a and 4b without short-circuiting the current path L1 via the magnetic materials 6a and 6b. In addition, by using the magnetic materials 6a and 6b and the magnetic material 5 in combination, the magnetic sensor elements 4a and 4b are arranged to be sandwiched by the magnetic material, and more magnetic field penetrates each magnetic sensitive portion vertically. The magnetic field can be detected with high sensitivity.

The thickness of the magnetic materials 6a and 6b (equal to the thickness of the bus bar 2) is one half of the length of the magnetic material 6 (equal to the separation distance of the slits 2a and 2b and the separation distance of the magnetic sensor elements 4a and 4b). If it is equal to, the improvement of the magnetic field detection sensitivity by the magnetic materials 6a and 6b is equal to the degree of the improvement of the sensitivity by the magnetic material 6, and if it is large, the improvement of the magnetic field detection sensitivity by the magnetic materials 6a and 6b is due to the magnetic material 6. It is better than the degree of improvement in sensitivity.

FIG. 7B shows yet another type of the magnetic material 6 in the current sensor 1 according to the present embodiment, that is, the magnetic material 6c. The magnetic material 6c has a flat plate portion and an upright portion. Similar to the magnetic material 6, the flat plate portion is formed into a rectangular plate shape and is arranged on the lower surface side of the bus bar 2 so as to face the magnetic sensor elements 4a and 4b. The erection portion is erected on both ends in the lateral direction of the flat plate portion, and like the magnetic materials 6a and 6b, the left side slit 2a and the right side of the two slits 2a and 2b formed in the bus bar 2 are formed. They are inserted into the space at the tip of the slit 2b, respectively, and are arranged so as to face the magnetic sensor elements 4a and 4b supported on the substrate 3. As the magnetic material 6c, since the standing portion is arranged in the slits 2a and 2b of the bus bar 2, a non-conductive material, for example, a material formed by using a nickel-based ferrite having a large resistance is used. As a result, the magnetic field generated by the current to be measured flowing in the bus bar 2 due to the small air gap without short-circuiting the current path L1 via the magnetic material 6c is generated by the magnetic sensitive portions of the magnetic sensor elements 4a and 4b. The magnetic field can be detected with high sensitivity by focusing a lot and putting it vertically.

In the current sensor 1 according to the present embodiment, the bus bar 2 is provided with two slits 2a and 2b, which extend vertically inward from the lower and upper outer edges in the vertical direction and are alternately arranged in the horizontal direction, respectively. , A configuration in which deflection sections La and Lb are formed around the tips of the left slit 2a and the right slit 2b of the two slits 2a and 2b, and these are arranged in the horizontal direction and included in series in the current path L1. Although adopted, the present invention is not limited to this, and a configuration in which the deflection sections La and Lb are arranged in the vertical direction and included in parallel in the current path may be adopted.

8A and 8B show the configuration of the current sensor 11 according to the modified example. Here, FIG. 8A shows the configuration of the current sensor 11 in a top view, and FIG. 8B shows the internal configuration of the current sensor 11 with respect to the reference line BB of FIG. 8A. The current sensor 11 includes a bus bar 12, a substrate 3, magnetic sensor elements 4a and 4b, a signal processing IC 4c, a package 4, magnetic materials 5 and 6, and insulating members 7 and 8. The current sensor 11 has a different configuration of the bus bar 12 from the current sensor 1 according to the previous embodiment, and correspondingly, the arrangement of the magnetic sensor elements 4a and 4b is different. Therefore, among the constituent parts of the current sensor 11, the parts that are the same as or correspond to the current sensor 1 according to the previous embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The bus bar 12 is an example of a conductor plate through which a current to be measured flows. Here, the currents to be measured are arranged vertically on the bus bar 12 along two paths (also referred to as current paths) L21 and L22 extending from one side in the horizontal direction to the other side and connecting between the two openings 2d. It flows separately. In this modification, as an example, the current to be measured is a direct current flowing from the left side to the right side in the horizontal direction on the bus bar 12. Similar to the bus bar 2 according to the previous embodiment, the bus bar 12 has a thickness larger than that of the substrate 3 (for example, 1.0 mm or more) in order to allow a large current to flow, and efficiently dissipates heat generated by the flow of the current. In order to release it, it is formed into a plate having a large surface using a metal having high thermal conductivity such as copper and aluminum. As an example, the bus bar 12 is formed in a rectangular shape having a longitudinal direction in the lateral direction, including an opening 12d and slits 12a, 12b, 12c.

One opening 12d is formed at both ends of the bus bar 12 in the horizontal direction, and one opening 12d is formed in the center in the vertical direction. Thereby, as described with reference to FIGS. 3A and 3B, the current sensor 11 can be fixed to the output terminal of the external device that outputs the measured current by using the fixture 9. The opening 2d is not limited to one formed at both ends of the bus bar 12, and two or more openings 2d may be formed at both ends.

The slits 12a, 12b, and 12c are examples of at least one slit formed in the bus bar 12, and thereby, a section in which the direction in which the current flows changes in at least a part of the current paths L21 and L22 extending in the lateral direction on the bus bar 12. La and Lb (called a deflection section) are provided. The slits 12a and 12b extend along a straight line parallel to the direction in which at least the tip end side intersects in the lateral direction from the lower and upper outer edges in the vertical direction of the bus bar 12, respectively. The slit 12c includes two slits 12c formed to be closed inside the bus bar 12, and is located on one side and the other side in the lateral direction with respect to the slits 12a and 12b, respectively, between the tips of the slits 12a and 12b. Extend in the direction of intersecting each other in the lateral direction so as to sandwich the portion in the lateral direction. As a result, deflection sections La and Lb included in the current paths L21 and L22 are formed around the tips of the slits 12a and 12b, respectively, and the current paths L21 and L22 are provided while maintaining heat dissipation by providing a large surface area of the bus bar 12. It can be turned in a direction other than the horizontal direction. That is, the current to be measured can flow in the bus bar 12 in a direction other than the lateral direction.

The direction of intersection in the horizontal direction is the vertical direction orthogonal to the horizontal direction in this modification, but is not limited to this, and the relative arrangement of the slits 12a, 12b, 12c and the deflection sections La, Lb described above is not limited to this. As long as it is maintained, it may be in any direction that intersects laterally. Further, for each of the slits 12a, 12b, and 12c, the directions in which they intersect in the lateral direction may be the vertical direction, or may be arbitrary directions other than the lateral directions different from each other.

The magnetic sensor elements 4a and 4b are sensors that detect a magnetic field generated by a current flowing in the bus bar 12, and are sealed in the package 4 together with the signal processing IC 4c as in the magnetic sensor elements 4a and 4b according to the previous embodiment. Has been done. However, the magnetic sensor elements 4a and 4b are provided at positions on the substrate 3 corresponding to the deflection sections La and Lb, respectively. Here, the positions corresponding to the deflection sections La and Lb are the positions inside the deflection sections La and Lb in which the directions of the current paths L21 and L22 change in the top view. The positions are located inside the tips of the slits 12a and 12b that form Lb, respectively. As a result, when the current to be measured flows separately along the current paths L21 and L22 in the bus bar 12, a magnetic field directed in the height direction is generated by the currents flowing in the deflection sections La and Lb, respectively, and these magnetic fields are generated. The magnitude of the current to be measured can be measured by detecting with magnetic sensor elements 4a and 4b provided on the upper surface of the bus bar 12 via the substrate 3 inside the deflection sections La and Lb, respectively.

FIG. 9 shows the details of the arrangement of the slits 12a, 12b, 12c on the bus bar 12 and the arrangement of the deflection sections La, Lb in the current paths L21, L22. As described above, the slits 12a and 12b each include one slit, and the slit 12c includes two slits. The slits 2a and 2b are formed so as to extend in the vertical direction from different outer edges (that is, lower and upper outer edges) of the bus bar 12 in the vertical direction toward the inner side (that is, the deflection sections La and Lb). ing. The two slits 12c are closed inside the bus bar 12 and vertically sandwich the portion between the tips of the slits 12a and 12b on one side and the other side in the horizontal direction with respect to the slits 12a and 12b, respectively. It is formed so as to extend in the direction.

The slits 12a and 12b have a length smaller than half the vertical width of the bus bar 12, and the two slits 12c have a length larger than the separation distance between the tips of the slits 12a and 12b. As a result, the current path L21 is on the bus bar 12 on the lower side of the drawing of the straight line L0 connecting the two openings 12d formed at both ends of the bus bar 12, avoiding the tip of the slit 12a and the lower end of the two slits 12c, respectively. It meanders and connects between the two openings 2d. That is, the current path L21 is oriented from the opening 2d on the left side of the drawing from the lower side to the upper side while avoiding the lower end of the slit 12c on the left side, and is oriented from the upper side to the lower side while avoiding the tip of the slit 12a, and is on the right side. Avoiding the lower end of the slit 12c, the direction is changed from the lower side to the upper side to reach the opening 2d on the right side. Here, the slit 12a forms a deflection section La that changes its direction downward in the vertical direction around the tip thereof. Further, the current path L22 meanders on the bus bar 12 on the upper side of the drawing of the straight line L0, avoiding the tip of the slit 12b and the upper end of the two slits 12c, respectively, and connects the two openings 2d. That is, the current path L22 is oriented from the opening 2d on the left side of the drawing from the upper side to the lower side while avoiding the upper end of the slit 12c on the left side, and is oriented from the lower side to the upper side while avoiding the tip of the slit 12b, and is on the right side. Avoiding the upper end of the slit 12c, the direction is changed from the upper side to the lower side to reach the opening 2d on the right side. Here, the slit 12b forms a deflection section Lb that changes its direction upward in the vertical direction around the tip thereof.

As described above, the slits 12a and 12b extending in the vertical direction from the different outer edges of the bus bar 12 are arranged vertically on the bus bar 12 with their respective tips facing each other, so that the two deflection sections La and Lb are vertically arranged. The current paths L21 and L22 are included in the current paths L21 and L22, respectively. Therefore, when the measured current flows in the bus bar 12 from the left opening 2d to the right opening 2d, the measured current is diverted, and the diverted current flows along the current paths L21 and L22, respectively, and is included in each path. It flows through the deflection sections La and Lb, and the strength corresponds to the amount of the current diverted inside each section, and the sum of the strengths generates a magnetic field corresponding to the magnitude of the current to be measured.

At this time, the two deflection sections La and Lb change the directions of the current paths L21 and L22 in different directions. A downward magnetic field is generated, and the remaining diverted current flows counterclockwise in the deflection section Lb when viewed from above, so that an upward magnetic field is generated in the height direction inside the deflection section Lb. Therefore, the magnetic sensor elements 4a and 4b provided on the upper surface of the bus bar 12 via the substrate 3 detect the magnetic fields in opposite directions generated inside the deflection sections La and Lb, respectively, and the signal processing IC 4c detects the magnetic sensor elements. By calculating the difference between the output signals of 4a and 4b, the signals derived from the magnetic field generated by the divided current are added together, and the noise derived from the external magnetic field entering from outside the current sensor 11 is canceled out, resulting in a high SN ratio. The magnitude of the current to be measured can be measured with. The current sensor 11 can measure a relatively large current to be measured with respect to the current sensor 1 according to the previous embodiment.

By adjusting the lateral distance between the two slits 12c with respect to the slits 12a and 12b, the strength of the magnetic field detected by the magnetic sensor elements 4a and 4b can be adjusted, and the detection sensitivity of the measured current can be adjusted. good. For example, in order to increase the magnetic field detected by the magnetic sensor elements 4a and 4b and improve the detection sensitivity, the lateral separation distance between the two slits 12c may be reduced to reduce the curvature of the deflection sections La and Lb. good. Further, in order to weaken the magnetic field detected by the magnetic sensor elements 4a and 4b and avoid saturation of the detection sensitivity, the lateral separation distance between the two slits 12c is increased to increase the curvature of the deflection sections La and Lb. You may. Further, the length and width of the slits 12a, 12b, 12c may be adjusted instead of or in addition to adjusting the lateral separation distance of the two slits 12c with respect to the slits 12a, 12b.

In the current sensor 11 according to the modified example, slits formed on the bus bar 12 with their tips facing each other and extending in the vertical direction from the lower and upper outer edges of the bus bar 12 in the vertical direction, respectively. With respect to 12a and 12b, two slits 12c formed by closing inside the bus bar 12 and extending in the vertical direction were arranged so as to sandwich the portion between the tips of the slits 12a and 12b in the horizontal direction. The two slits 12a and 12b are arranged in the horizontal direction with their respective tips facing each other in the vertical direction, and the pair of slits 12a and 12b facing each other in the vertical direction and the other pair facing in the vertical direction. One slit 12c may be arranged so as to separate the two portions from the portion between the tips of the slits 12a and 12b. As a result, deflection sections La and Lb included in the current paths L21 and L22 are formed around both ends of one slit 12c, and the current paths L21 and L22 are provided while maintaining heat dissipation by providing a large surface area of the bus bar 12. It can be turned in a direction other than the horizontal direction. That is, the current to be measured can flow in the bus bar 12 in a direction other than the lateral direction.

In the current sensor 1 of the present embodiment and the current sensor 11 according to the modified example, the upper surfaces of the magnetic sensor elements 4a and 4b and the signal processing IC 4c are electrostatically shielded with a non-magnetic conductive material such as aluminum. It may be that. As a result, electrostatic noise coming from the upper surface side of the package 4 can be shielded. Further, in the non-magnetic conductive material, a plurality of slits may be provided in the portions facing the magnetic sensor elements 4a and 4b. The plurality of slits are, for example, a plurality of notches opening at the outer edge of the conductive film material, each of which is arranged in the vertical direction with the longitudinal direction oriented laterally. As a result, the eddy current generated when the magnetic field enters the conductive film material is suppressed, and deterioration of the response of the magnetic sensor elements 4a and 4b due to the magnetic field generated by the eddy current can be avoided.

Further, in the slits 2a and 2b provided in the bus bar 1 of the present embodiment and the slits 12a, 12b and 12c provided in the bus bar 12 according to the modified example, the mechanical strength of the bus bar whose width has been narrowed by slit processing is increased. In order to reinforce, at least a part of the slit groove may be filled with an insulating adhesive, resin or the like.

In the current sensor 1 of the present embodiment and the current sensor 11 according to the modified example, the currents energizing the current paths L1, L21, and L22 may be direct current or alternating current. Further, in the case of direct current, the direction of the energizing current may be arbitrarily determined.

In the current sensor 1 of the present embodiment and the current sensor 11 according to the modified example, a configuration is adopted in which the measured current is measured from the difference between the detection results using two magnetic sensor elements 4a and 4b. However, a configuration in which the current to be measured is measured from the detection result using one magnetic sensor element may be adopted. Further, in the current sensor 1, the magnetic sensor elements 4a and 4b are not limited to be provided at positions on the substrate 3 corresponding to the inside of the tips of the left slit 2a and the right slit 2b of the two slits 2a and 2b, respectively. Further, one magnetic sensor element may be provided at a position on the substrate 3 corresponding to the inside of the tip of the slit 2a on the right side and the slit 2b on the left side. In such a case, the measured current may be measured by combining the differences in the detection results of each one magnetic sensor element. Further, in the drawings, the magnetic sensor elements 4a and 4b and the signal processing IC 4c are described as separate ones, but the magnetic sensor elements 4a and 4b and the signal processing IC 4c are formed as one in the same silicon substrate. May be done.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the above embodiments. It is clear from the description of the claims that such modified or improved forms may also be included in the technical scope of the present invention.

The order of execution of operations, procedures, steps, steps, etc. in the devices, systems, programs, and methods shown in the claims, specification, and drawings is particularly "before" and "prior to". It should be noted that it can be realized in any order unless the output of the previous process is used in the subsequent process. Even if the scope of claims, the specification, and the operation flow in the drawings are explained using "first", "next", etc. for convenience, it means that it is essential to carry out in this order. It's not a thing.

1 ... Current sensor, 2 ... Bus bar, 2a, 2b, 2c ... Slit, 2d ... Opening, 3 ... Substrate, 3a ... Main body, 3b ... Stretched part, 4 ... Package, 4a, 4b ... Magnetic sensor element, 4c ... Signal Processing ICs, 5, 6, 6a, 6b, 6c ... Magnetic materials, 7, 8 ... Insulating members, 9 ... Fixtures, 10 ... Output terminals, 10d ... Openings, 11 ... Current sensors, 12 ... Bus bars, 12a, 12b, 12c ... slit, 12d ... opening, L0 ... straight line, L1, L21, L22 ... current path.

Claims (22)

The current to be measured flows along a path including a section extending between the first opening and the second opening formed on one side and the other side in the uniaxial direction and at least partially changing the direction in which the current flows. Conductor plate and
A substrate fixed on one surface of the conductor plate and
A magnetic sensor provided at a position corresponding to the section on the substrate and detecting a magnetic field generated by a current flowing through the section is provided.
The section includes first and second sections whose directions change to one side and the other side in a direction intersecting the uniaxial direction, respectively.
The conductor plate extends inward from the outer edge of the conductor plate in a direction in which at least the tip end side intersects the uniaxial direction, and extends from the outer edge of the other side of the conductor plate to the first section. The slit, the second slit extending from the outer edge of the conductor plate on the one side to the second section, and the one of the conductor plate arranged between the first opening and the first slit. A fourth slit extending inward from the outer edge of the side, arranged between the second opening and the second slit, and extending inward from the outer edge of the other side of the conductor plate. Slits and are formed,
The direction crossing the axial direction, both of the first slit and the fourth slit, each tip connecting the said first opening and said second opening located on the surface of the conductor plate and has a length of just by position on the one side of the conductor plate with respect to the straight line, both of the second slit and the third slit, said conductive plate each of tip relative to the straight line Has a length sufficient to be located on the other side of the
The magnetic sensor is provided on the conductor plate via the substrate, and is arranged at least one of the inside of the first slit or the inside of the second slit in a top view.
The substrate is fixed to the conductor plate on a surface opposite to the surface on which the magnetic sensor is mounted, and the first slit, the second slit, and the third slit are viewed from above. , And are arranged so as to overlap the fourth slit.
Current sensor. The current sensor according to claim 1, wherein the board is a flexible printed wiring board. The substrate has a main body portion that supports the magnetic sensor, and an extension portion that is provided with a wiring pattern for transmitting a signal of the magnetic sensor and extends from the main body portion to the outside of the conductor plate. 2. The current sensor according to 2. Further provided with a package for sealing the magnetic sensor
The current sensor according to any one of claims 1 to 3, wherein the back surface side of the magnetic sensor is exposed on one surface of the package facing the substrate. The current sensor according to claim 4, wherein the package seals a signal processing IC that processes a detection signal of the magnetic sensor together with the magnetic sensor. The current sensor according to claim 4 or 5, further comprising a first magnetic material facing the magnetic sensor on the other side of the package facing the substrate with respect to the one side. The current sensor according to any one of claims 1 to 6, wherein the conductor plate has a thickness larger than that of the substrate. The current sensor according to any one of claims 1 to 7, wherein the magnetic sensor includes first and second magnetic sensors provided at positions on the substrate corresponding to the first and second sections, respectively. The current sensor according to any one of claims 1 to 8, wherein the first and second sections are arranged in a row in the uniaxial direction. The current sensor according to any one of claims 1 to 8, wherein the first and second sections are arranged separately in the intersecting directions. The current sensor according to any one of claims 9 and 10, which calculates the amount of the current to be measured from the difference between the output signals of the first and second magnetic sensors, and claims 8. The current sensor according to any one of claims 1 to 11, wherein the substrate covers at least a part of the first slit and the second slit. The current sensor according to any one of claims 1 to 12, further comprising a second magnetic material arranged so as to face the magnetic sensor on the other side of the conductor plate with respect to the one surface. The invention according to any one of claims 1 to 12, further comprising a second magnetic material arranged so as to face the magnetic sensor in at least one of the first slit and the second slit. Current sensor. A flat plate portion arranged on the other side of the conductor plate on the other side of the conductor plate facing the magnetic sensor, and at least one of the first slit and the second slit standing on the flat plate portion. The current sensor according to any one of claims 1 to 12, further comprising a second magnetic material having an upright portion arranged in. The current sensor according to claim 13, further comprising an insulating member provided between the conductor plate and the second magnetic material. The current sensor according to any one of claims 13 to 15, wherein the second magnetic material includes a non-conductive material. The current sensor according to any one of claims 1 to 17, wherein at least a part of the first slit and the second slit is filled with an insulating adhesive or resin. The current sensor according to any one of claims 1 to 18, further comprising another insulating member provided between the conductor plate and the substrate. The current sensor according to any one of claims 1 to 19, wherein the wiring pattern provided on the substrate is insulated from the conductor plate. The current sensor according to any one of claims 1 to 20, wherein the magnetic sensor is made of a compound semiconductor. The current sensor according to claim 5, wherein the magnetic sensor and the signal processing IC are formed on the same silicon substrate.

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