JP2012154831A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in which when a magnetic sensor is mounted on a substrate in a magnetic proportion system current sensor, the substrate should be arranged in parallel with a longitudinal direction of a bus bar and an installation angle cannot be changed, and thereby, it is difficult to integrate substrates arranged on a plurality of bus bars arranged in parallel with each other to one substrate.SOLUTION: A current sensor 10 includes a sub bus bar 14 connected to a main bus bar 12 to be a current path. The sub bus bar 14 is connected to the main bus bar 12 so that a current measurement part 26 is extended at an angle different from a longitudinal direction La of the main bus bar 12. Thereby, a part of current flowing into the main bus bar 12 is branched to the sub bus bar 14. The current sensor 10 also includes: a core 16 formed like a partially notched annular shape and inserting the current measurement part into a hollow part 17; and a substrate 22 assembled with a magnetic sensor 20 and inserted into a gap part 18 of the core 16 together with the magnetic sensor 20.

Description

  The present invention relates to a current sensor.

  A so-called hybrid vehicle, electric vehicle, or the like that uses a rotating electrical machine as a drive source is equipped with a power converter such as a battery or an inverter that serves as a power source. In addition, conventionally, a metal plate called a bus bar has been used as a current path for supplying a current from the power converter to the rotating electrical machine. The bus bar is an elongated flat plate-like metal plate, and has a large cross-sectional area of the conductor as compared with a covered electric wire such as a cable, and is suitable for supplying a large current because the conductor is exposed and has a high heat dissipation effect.

  In order to measure the amount of current supplied to the rotating electrical machine, a current sensor is conventionally arranged on the bus bar. As this current sensor, a magnetic proportional (open loop) type is widely used. The magnetic proportional current sensor is configured to include a core surrounding the bus bar and a magnetic sensor disposed in a gap portion (notch portion) of the core.

  When a current flows through the bus bar, a magnetic field in the clockwise direction with respect to the direction of the current is generated (so-called right-handed rule), and this magnetic field is converged on the magnetic path of the core. Further, a magnetic sensor arranged in the gap portion of the core detects the strength of the magnetic field, and the amount of current is calculated based on the detected strength of the magnetic field.

  FIG. 9 shows a conventional current sensor 100. In FIG. 9, the rotating electrical machine to which current is supplied is of a three-phase AC type, and accordingly, three bus bars 101 are arranged in parallel. A magnetic core 102 is sandwiched between the bus bars 101, and a magnetic sensor 105 is disposed in the gap portion 104 of the magnetic core 102. In addition, the magnetic sensor 105 and the amplifier circuit 106 of the substrate 110 are electrically connected via a connection wiring 107 such as a wire harness or a pin. The substrate 110 is mounted with an amplifier circuit 106, an arithmetic circuit 108 that performs arithmetic processing on the amplified signal, and the like.

  In recent years, various methods for achieving miniaturization and simplification of the above-described current sensor have been proposed. For example, in Patent Document 1, the current sensor is reduced in size and simplified by mounting a magnetic sensor on a substrate on which a subsequent circuit such as an amplifier circuit or an arithmetic circuit is mounted, thereby eliminating connection wiring. Further, in Patent Document 2, a sub bus bar is connected to a main bus bar, and a small current flowing through the sub bus bar is measured with a small magnetic core to reduce the size of the magnetic core.

JP 2010-223722 A JP 2008-170244 A

  In order to further simplify the board on which the magnetic sensor is mounted, it is conceivable to integrate the boards respectively arranged on the plurality of adjacent bus bars into one board. However, when the magnetic sensor is mounted on the substrate, the installation angle of the substrate is limited based on the detection angle of the magnetic sensor, and as a result, the substrates arranged on each bus bar cannot be integrated into one substrate.

  That is, as shown in FIG. 10, a current flows through the bus bar 101 along the longitudinal direction L1, and a magnetic field is generated on a plane perpendicular to the current direction L1. Therefore, the magnetic path of the magnetic core must be arranged so as to be perpendicular to the longitudinal direction L1 of the bus bar 101. Furthermore, the detection surface (magnetic sensitive surface) 112 of the magnetic sensor must be arranged so as to be perpendicular to the magnetic path 111 of the magnetic core. For this reason, the detection surface 112 of the magnetic sensor must be arranged parallel to the longitudinal direction L1 of the bus bar 101. When the magnetic sensor is mounted on the substrate, the magnetic sensor is disposed on the substrate so that the detection surface 112 of the magnetic sensor is parallel to the mounting surface of the substrate. Accordingly, the board on which the magnetic sensor is mounted needs to be installed so as to be parallel to the longitudinal direction L1 of the bus bar 101.

  FIG. 11 shows a state in which conventional current sensor units 100 ′ A to 100 ′ C in which the magnetic sensor 105 is mounted on the substrate 110 are arranged on the bus bars 101 </ b> A to 101 </ b> C. The bus bars 101A to 101C are arranged in parallel. In order to integrate the current sensor units 100′A to 100′C into one board, the board 110 is arranged non-parallel to the longitudinal direction L1 of the bus bar 101. There is a need to. However, the substrate 110 must be parallel to the longitudinal direction L1 of the bus bar 101 due to the above-described restrictions, and this installation angle cannot be changed. As a result, each substrate 110 cannot be integrated into one substrate.

  Therefore, an object of the present invention is to provide a current sensor that can be integrated with an adjacent substrate even if the magnetic sensor is mounted on the substrate.

  The present invention relates to a current sensor. The current sensor is connected to the bus bar so that the current measurement unit extends at an angle different from the longitudinal direction of the bus bar serving as a current path, and a sub bus bar to which a part of the current flowing through the bus bar is diverted, and a part of the current sensor is notched A core that is formed in an annular shape and into which the current measurement unit is inserted into the hollow portion, and a substrate that is assembled with the magnetic sensor and that is inserted into the cutout portion of the core together with the magnetic sensor.

  In the above invention, it is preferable that a current is supplied from the inverter to the rotating electrical machine via the bus bar, and the substrate is a main substrate on which a control circuit for the inverter and the rotating electrical machine is formed.

  In the above invention, it is preferable that a fixing member for fixing the core to the current measuring portion is provided, and the fixing member has a board insertion slot formed at a position corresponding to the notch portion.

  Further, in the above invention, it is preferable that the plurality of bus bars are arranged so as to be parallel to each other, and the sub bus bars are connected to each bus bar so that the current measuring unit extends perpendicularly to the longitudinal direction of the bus bar. It is. Further, it is preferable that a core is inserted into each current measuring unit, and a plurality of magnetic sensors inserted into the notch portions of each core are assembled to the substrate.

  According to the present invention, adjacent substrates can be integrated even if the magnetic sensor is mounted on the substrate.

It is a figure which illustrates the component of the current sensor which concerns on this embodiment. It is a figure explaining the assembly process of the current sensor which concerns on this embodiment. It is a figure explaining the assembly process of the current sensor which concerns on this embodiment. It is a figure which illustrates the current sensor concerning this embodiment. It is a figure explaining the flow of the current in the current sensor concerning this embodiment. It is a figure which illustrates the current sensor which concerns on other embodiment. It is sectional drawing of the current sensor which concerns on the said other embodiment. It is a figure which illustrates the current sensor which concerns on other embodiment. It is a figure which illustrates the conventional current sensor. It is a figure explaining the installation angle of a current sensor. It is a figure which illustrates the conventional current sensor at the time of mounting a magnetic sensor on a board | substrate.

  FIG. 1 shows a current sensor according to the present embodiment for each component. The current sensor 10 is mounted with a sub bus bar 14 electrically connected to the main bus bar 12, a core 16 sandwiching the sub bus bar 14, a magnetic sensor 20 disposed in a gap portion 18 of the core 16, and a magnetic sensor 20 (assembly). And a substrate 22).

  The main bus bar 12 is a plate-like member extending in a predetermined direction, and is used as a current path for supplying an alternating current from an inverter (not shown) to the rotating electrical machine. The rotary electric machine is, for example, a three-phase AC type, and three main bus bars 12 are used to supply an AC current of each phase to the rotary electric machine. The main bus bars 12 are arranged in parallel to each other along a direction perpendicular to the longitudinal direction L1. In order to simplify the description, only one main bus bar 12 is shown in FIG.

  The main bus bar 12 is exposed without being covered with an insulating protective film or the like, and is configured to have a higher heat dissipation effect than the covered electric wire. The cross-sectional area of the main bus bar 12 is formed so as to be larger than the cross-sectional area of the conductor of the covered electric wire. Since the main bus bar 12 has such characteristics, the main bus bar 12 has a structure suitable for supplying a large current as compared with the covered electric wire. The main bus bar 12 is made of a metal material having high conductivity and heat dissipation, and is made of, for example, copper or aluminum.

  The main bus bar 12 includes a substantially rectangular flat plate portion 13 and connection portions 15A and 15B connected to both side end portions (side ends viewed from the longitudinal direction L1) of the flat plate portion 13. At both ends of the flat plate portion 13 in the longitudinal direction L1, terminals of an inverter and a rotating electric machine and a bus bar for connection are connected. Further, the connecting portions 15A and 15B are bent at a predetermined angle (90 ° in FIG. 1) with respect to the flat plate portion 13.

  The sub bus bar 14 is connected to the connection portions 15A and 15B of the main bus bar 12. The sub bus bar 14 has a shape obtained by bending a substantially rectangular flat plate into a crank shape, and includes connection portions 24A and 24B provided at both ends, and a current measurement portion 26 that connects the connection portion 24A and the connection portion 24B. It consists of Similar to the main bus bar 12, the sub bus bar 14 is made of a metal material having high conductivity and high heat dissipation, and is made of, for example, copper or aluminum.

  The current measurement unit 26 is bent with respect to the connection unit 24A and the connection unit 24B, and when the sub bus bar 14 is coupled to the main bus bar 12, the longitudinal direction L1 of the main bus bar 12 and the longitudinal direction of the current measurement unit 26 of the sub bus bar 14 are combined. It is bent so that the direction L2 forms a predetermined angle. The predetermined angle is determined according to the installation angle of the substrate 22 inserted into the gap portion 18 of the core 16 sandwiched between the current measuring portions 26. As will be described later, since the current measuring unit 26 and the substrate 22 are arranged so as to be parallel to each other, the predetermined angle is the substrate 22 with respect to the longitudinal direction L1 of the main bus bar 12 when the current sensor 10 is assembled. Is equal to the installation angle α.

  For example, when the installation angle α is 90 °, when the main bus bar 12 is connected to the sub bus bar 14, the angle formed by the longitudinal direction L1 of the main bus bar 12 and the longitudinal direction L2 of the current measuring unit 26 of the sub bus bar 14 is The shape of the sub bus bar 14 is determined to be 90 ° (= α). Specifically, the longitudinal direction L3 of the connecting portions 24A and 24B is formed to be parallel to the longitudinal direction L1 of the main bus bar 12, and the longitudinal direction L3 of the connecting portions 24A and 24B and the longitudinal direction L2 of the current measuring unit 26 are The sub bus bar 14 is formed so that is vertical.

  Further, the cross-sectional area of the sub bus bar 14 is formed to be smaller than the cross-sectional area of the main bus bar 12. By making the cross-sectional area of the sub bus bar 14 smaller than the cross-sectional area of the main bus bar 12, the amount of current flowing through the sub bus bar 14 becomes smaller than the amount of current flowing through the main bus bar 12. Therefore, the magnetic field generated in the current measuring unit 26 of the sub bus bar 14 is also weaker than the magnetic field generated in the main bus bar 12.

  Further, the connection portions 24A and 24B of the sub bus bar 14 are provided with fastening holes 27A and 27B. When connecting to the main bus bar 12, the fastening holes 27A and 27B are aligned with the fastening holes 28A and 28B of the connecting portions 15A and 15B of the main bus bar 12, and then the fastening holes 27A and 27B and the fastening holes 28A and 28B. The fastening member 29 is inserted into (screwed into).

  The core 16 has a ring shape (C shape) with a part cut away, and a gap portion 18 (notch portion) is formed on the magnetic path MP. The gap portion 18 is formed by cutting the core 16 perpendicular to the magnetic path MP, and is connected to the hollow portion 17. The core 16 is made of a material having high magnetic permeability, and is made of, for example, an amorphous alloy or permalloy. The core 16 is sandwiched between the sub bus bars 14 instead of being sandwiched between the main bus bars 12 as in the prior art. As described above, the current amount of the sub bus bar 14 is smaller than the current amount of the main bus bar 12, and thus the generated magnetic field is weaker than that of the main bus bar 12. When the core is sandwiched between the main bus bars 12, it is necessary to use a large core to prevent magnetic saturation. However, the sub bus bar 12 can use a smaller core 16 than the conventional one because the magnetic field is weakened. .

  The magnetic sensor 20 is an element that detects a magnetic flux converged on the magnetic path MP, and is composed of, for example, a Hall element. The magnetic sensor 20 is mounted on the substrate 22. During the mounting, the magnetic sensor 20 is assembled to the substrate 22 so that the detection surface 38 of the magnetic sensor 20 is parallel to the mounting surface 23 of the substrate.

  In addition to the magnetic sensor 20, an amplifier 34 that amplifies the output signal of the magnetic sensor 20 and an arithmetic unit 36 that performs arithmetic processing on the amplified signal are mounted on the mounting surface 23 on the substrate 22. The substrate 22 is composed of a resin substrate such as a glass epoxy substrate or a bakelite substrate.

  Next, assembly of the current sensor 10 according to the present embodiment will be described. First, the current measurement part 26 of the sub bus bar 14 is inserted from the gap part 18 of the core 16 into the hollow part 17. At this time, the core 16 is inserted so that the magnetic path MP is perpendicular to the longitudinal direction L <b> 2 of the current measuring unit 26. Here, the vertical is not limited to 90 ° with respect to the longitudinal direction L2, but may be any angle that can converge the magnetic flux generated based on the current flowing along the longitudinal direction L2 of the current measuring unit 26. For example, it is assumed to include an angle range of 80 ° to 100 ° with respect to the longitudinal direction L2.

  Next, as shown in FIG. 2, the sub bus bar 14 on which the core 16 is arranged is connected to the main bus bar 12. Specifically, the fastening holes 28A and 28B in the connection parts 15A and 15B of the main bus bar 12 and the fastening holes 27A and 27B in the connection parts 24A and 24B of the sub bus bar 14 are aligned. Thereafter, the sub bus bar 14 is connected and fixed to the main bus bar 12 by inserting (screwing) fastening means 29 such as screws into the respective fastening holes. By connecting the sub bus bar 14 to the main bus bar 12, the sub bus bar 14 functions as a branch path for the main current of the main bus bar 12. Further, as described above, the longitudinal direction L2 of the current measuring unit 26 of the sub bus bar 14 extends perpendicularly to the longitudinal direction L1 of the main bus bar 12.

  Next, as shown in FIG. 3, the magnetic sensor 20 is inserted into the gap portion 18 of the core 16 together with the substrate 22. At this time, since the gap portion 18 is formed perpendicular to the magnetic flux MP of the core 16, when the substrate 22 is inserted into the gap portion 18, the detection surface (magnetic sensitive surface) 38 of the magnetic sensor 20 is relative to the magnetic path MP. Arranged vertically. Further, since the detection surface 38 is mounted on the substrate 22 so as to be parallel to the mounting surface 23 of the substrate 22, the substrate 22 is also perpendicular to the magnetic path MP. Here, the term “perpendicular” is not limited to 90 ° with respect to the magnetic path MP, but may be any angle as long as the detection surface 38 can accurately detect the magnetic path MP. Includes angle ranges up to °.

  By adopting the above arrangement structure, the substrate 22 is arranged perpendicular to the longitudinal direction L1 of the main bus bar 12. The current sensor 10 having such an arrangement structure is arranged on each of the three main bus bars 12 arranged in parallel, and the mounting surfaces 23 of the substrates 22 arranged on the respective main bus bars 12 are parallel to each other. . Further, by connecting the sub bus bar 14 to the main bus bar 12 so that the current measuring portions 26 of the sub bus bars 14 connected to the main bus bars 12 are arranged in a straight line, the respective substrates 22 arranged on the main bus bars 12 are arranged. Are also arranged in a straight line. Accordingly, it is possible to integrate each substrate 22 into one substrate. FIG. 4 shows a state in which the respective substrates 22 are integrated. By integrating the substrates 22 arranged on the main bus bars 12A to 12C into one, it is possible to simplify the substrates that have been individually arranged conventionally.

  Next, the calculation process of the current flow in the current sensor 10 and the current amount of the main bus bar 12 will be described with reference to FIG. A main current I1 flows through the flat plate portion 13 of the main bus bar 12 along the longitudinal direction L1. Further, the branch current I2 of the main current I1 flows into the sub bus bar 14 from the connection portion 24A. The branch current I2 flows in the sub bus bar 14 while changing the flow direction in the order of the longitudinal direction L3 of the connecting portion 24A → the longitudinal direction L2 of the current measuring portion 26 → the longitudinal direction L3 of the connecting portion 24B, and the main current I1 at the connecting portion 24B. To join. Here, when attention is paid to the current flowing through the current measuring unit 26, the current flows in the longitudinal direction L2, and thus a magnetic field is generated clockwise as viewed from the longitudinal direction L2. This magnetic field is converged on the magnetic path MP in the core 16. The detection surface 38 of the magnetic sensor 20 arranged perpendicular to the magnetic path MP detects the strength of the magnetic field in the magnetic path MP. The amount of branch current I2 is calculated based on the detected magnetic field strength. Further, the amount of main current I1 is calculated based on the amount of branch current I2 and the cross-sectional area ratio between main bus bar 12 and sub bus bar 14. Here, a storage unit such as a memory may be mounted on the substrate 22, and the cross-sectional area ratio between the main bus bar 12 and the sub bus bar 14 may be stored in the storage unit in advance.

  In the above-described embodiment, the boards 22 arranged on each main bus bar 12 are integrated into one board. In addition to this, the integrated board is further combined with a control circuit for a rotating electric machine, an inverter, and other vehicles. The control system may be integrated into a main board (motherboard). This is possible when the main board is arranged perpendicular to the main bus bar 12. By integrating the current sensor 10 on the main board, it is possible to further simplify the components.

  Moreover, the current sensor 10 according to the present embodiment may include a fixing member 42 that fixes the core 16 and the current measuring unit 26 as illustrated in FIG. 6. The fixing member 42 is formed with a slot 40 for inserting the substrate 22 into the gap portion 18 of the core 16. The fixing member 42 is made of an insulating material such as resin, and is formed by insert molding, for example.

  FIG. 7 shows a cross-sectional view taken along plane A of FIG. The fixing member 42 is formed so as to cover the core 16 in a state where the core 16 is disposed in the current measuring unit 26 of the sub bus bar 14. Both are fixed by covering the current measuring unit 26 and the core 16. 6 and 7, a part of the main bus bar 12 is also covered with the fixing member 42, but if it is desired to avoid a decrease in the heat dissipation effect due to the covering with the fixing member 42, the main bus bar 12 is fixed with the fixing member 42. You may make it not cover.

  A mold is used so that the resin does not enter the gap portion 18 and the hollow portion 17 of the core 16 during the molding. For example, the metal mold | die in which the board part which plugs up the gap part 18 and the hollow part 17 was formed is used. This plate portion may be formed to have the same width and thickness as the substrate 22 in FIG. By forming the fixing member 42 using such a mold, the fixing member 42 is provided with a slot 40 having an opening width equal to that of the substrate 22 and reaching the gap portion 18 of the core 16. The current sensor of each main bus bar 12 is assembled by inserting the substrate 22 into the slot 40 and aligning the magnetic sensor 20 of the substrate 22 with the gap portion 18 of the core 16.

  Further, as shown in FIG. 8, when the main bus bar 12 has an L shape, the fixing member 42 may be formed along the L shape. At this time, before the fixing member 42 is cured, a nut (not shown) having the same diameter as that of the connection hole 44 is embedded in the lower portion of the connection hole 44 at the end of the main bus bar 12. When connecting the rotating electric machine side bus bar or the like to the end of the main bus bar 12, the connecting hole of the rotating electric machine side bus bar and the connecting hole 44 of the main bus bar 12 are aligned, and bolts are inserted into both connecting holes and nuts ( Both bus bars are fixed by screwing. By adding means for fixing a plurality of bus bars to the fixing member 42, the assemblability is improved.

  DESCRIPTION OF SYMBOLS 10 Current sensor, 12 Main bus bar, 13 Flat plate part, 14 Sub bus bar, 15A, 15B Main bus bar connection part, 16 Core, 17 Hollow part, 18 Gap part, 20 Magnetic sensor, 22 Substrate, 23 Substrate mounting surface, 24A, 24B Sub bus bar connection part, 26 Current measurement part, 27A, 27B Sub bus bar fastening hole, 28A, 28B Main bus bar fastening hole, 29 fastening means, 34 amplifier, 36 computing unit, 38 detection surface, 40 slots, 42 fixing member, 44 connection hole.

Claims (4)

A sub-bus bar that is connected to the bus bar so that the current measurement unit extends at an angle different from the longitudinal direction of the bus bar that becomes the current path, and a part of the current flowing through the bus bar is shunted;
A core that is formed in a ring shape with a part cut away, and the current measuring part is inserted into the hollow part;
A magnetic sensor is assembled, and a substrate inserted into the core notch together with the magnetic sensor;
A current sensor comprising: The current sensor according to claim 1,
Current is supplied from the inverter to the rotating electrical machine via the bus bar,
The current sensor according to claim 1, wherein the substrate is a main substrate on which a control circuit for the inverter and the rotating electrical machine is formed. The current sensor according to claim 1 or 2,
A fixing member for fixing the core to the current measuring unit;
The current sensor according to claim 1, wherein a substrate insertion slot is formed in the fixing member at a position corresponding to the notch. The current sensor according to any one of claims 1 to 3,
A plurality of the bus bars are arranged in parallel to each other,
The sub bus bar is connected to each bus bar so that the current measuring unit extends perpendicularly to the longitudinal direction of the bus bar,
The core is inserted for each of the current measuring units,
A current sensor, wherein the substrate is assembled with a plurality of the magnetic sensors to be inserted into the cutout portions of the cores.