JP2010019747A - Electric current detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric current detector which suppresses the effect of a magnetic flux generated by a current flowing through an adjacent other current path on a magnetic flux detector installed for each current path, and accurately detects the current flowing through the current path. <P>SOLUTION: In this current detecting device, a first current path 7a and a second current path 7b are flat-plate-shaped conductors and are disposed in the state wherein the first current path 7a and the second current path 7b are lined up on the same plane, and the magnetic flux detectors 6a and 6b are disposed in positions P and Q where lines of magnetic force of magnetic fields generated respectively from the first current path 7a and the second current path 7b by the current flowing through the first current path 7a and the second current path 7b intersect perpendicularly each other, so that directions of detection of the magnetic flux which perpendicularly intersect two directions of detection of the magnetic flux by detectors 6a and 6b, agree with the direction of the line of magnetic force of the magnetic field generated from the first current path 7a, and with that of the line of magnetic force of the magnetic field generated from the second current path 7b. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a current detection device that detects a current flowing in a plurality of current paths such as a three-phase motor using a magnetic flux detector provided in the vicinity of each current path.

  Conventionally, a coreless current sensor has been used to detect a current flowing in a current path of each phase such as a three-phase motor. This coreless current sensor detects the magnetic flux generated around the current path when current flows with high sensitivity and high accuracy, and converts the current value. The size of the device is smaller than that of the current detection sensor with a core. In addition, the cost can be reduced.

  However, since the coreless current sensor is highly sensitive, it is easily affected by the magnetic flux generated by the current flowing in the current paths of other adjacent phases, and therefore the detected current value is corrected by software calculation. Need to be added.

  On the other hand, a current sensor for detecting a magnetic flux in the vicinity of the first current path provided to detect a current flowing in the first current path among the plurality of current paths, and the above-mentioned among the plurality of current paths There has been proposed a current detection device including a magnetic shield that reduces magnetic interference to the current sensor with respect to a second current path arranged at a position where magnetic interference can be given to the current sensor (for example, Patent Literature 1). 1).

  According to this current detection device, the size and thickness of the magnetic shield applied to the current path in order to reduce magnetic interference is small, so that the current flowing through each current path can be detected with high sensitivity in a smaller space. Is obtained.

Also, in a three-phase motor with a delta connection or neutral grounded star connection winding, the AC current that flows through two (two-phase) current paths out of the three-phase AC current that causes the sum of the flowing currents to be zero Is detected using two magnetic flux detectors, and a current detection device that detects an alternating current (each phase of three phases) flowing in three current paths by a microcomputer has been proposed (for example, Patent Documents). 2).
JP 2006-112698 A JP 2007-303988 A

  However, in the current detection device described in Patent Document 1, it is necessary to separately arrange a magnetic shield for avoiding magnetic interference with respect to the magnetic detector provided for each current path. For this reason, there are inconveniences such as an increase in manufacturing process and a decrease in mass productivity due to an increase in cost due to the installation of the magnetic shield.

  Moreover, in the current detector described in Patent Document 2, it is necessary to perform a complex current value calculation for three phases using a microcomputer from the magnetic flux detection output for two phases.

  The present invention has been made in view of the above-described problems, and its purpose is to suppress the influence of magnetic flux generated by the current flowing in another adjacent current path with respect to the magnetic flux detector installed for each current path, An object of the present invention is to provide a current detector that can accurately detect a current flowing in a current path.

In order to achieve the above-described object, the current detection device according to the present invention is characterized by the following (1), (2), and (3).
(1) a first current path;
A second current path;
One magnetic flux detector in which the magnetic flux detection direction for detecting the magnetic flux is limited to one direction;
A current detection sensor main body for detecting a current value of a current flowing in at least one of the first current path and the second current path based on the magnetic flux detected by the one magnetic flux detector;
With
The first current path and the second current path are flat-plate conductors and are arranged in a line on the same plane,
In the one magnetic flux detector, the directions of magnetic lines of magnetic force generated from the first current path and the second current path are orthogonal to each other by the current flowing through the first current path and the second current path, respectively. The magnetic flux detection direction is arranged at a position such that the direction of the magnetic field lines of the magnetic field generated from the first current path or the direction of the magnetic field lines of the magnetic field generated from the second current path matches.
thing.
(2) a first current path;
A second current path;
A first magnetic flux detector in which a magnetic flux detection direction for detecting magnetic flux is limited to one direction;
A second magnetic flux detector in which the magnetic flux detection direction for detecting the magnetic flux is limited to one direction;
A current detection sensor main body for detecting a current value of a current flowing through the first current path and the second current path based on the magnetic flux detected by the first magnetic flux detector and the second magnetic flux detector; ,
With
The first current path and the second current path are flat-plate conductors and are arranged in a line on the same plane,
In the first magnetic flux detector, magnetic field lines of magnetic fields generated from the first current path and the second current path, respectively, by currents flowing through the first current path and the second current path are orthogonal to each other. 1 is arranged so that the magnetic flux detection direction coincides with the direction of the magnetic field lines of the magnetic field generated from the first current path,
In the second magnetic flux detector, the magnetic field lines of the magnetic fields generated from the first current path and the second current path, respectively, by the current flowing through the first current path and the second current path are orthogonal to each other. The magnetic flux detection direction is arranged at a second position different from the first position so that the magnetic flux detection direction coincides with the direction of the magnetic force lines of the magnetic field generated from the second current path.
thing.
(3) a first current path;
A second current path;
One magnetic flux detector limited to two directions in which magnetic flux detection directions for detecting magnetic flux are orthogonal,
A current detection sensor main body for detecting a current value of a current flowing through each of the first current path and the second current path based on the magnetic flux detected by the one magnetic flux detector;
With
The first current path and the second current path are flat-plate conductors and are arranged in a line on the same plane,
The one magnetic flux detector is located at a position where magnetic field lines of magnetic fields generated from the first current path and the second current path are orthogonal to each other by currents flowing through the first current path and the second current path, respectively. The magnetic flux detection direction is arranged so as to match the direction of the magnetic field lines of the magnetic field generated from the first current path and the direction of the magnetic field lines of the magnetic field generated from the second current path.
thing.

According to the current detection device having the above configuration (1) or (2), the magnetic flux detector can detect the magnetic flux from at least one current path that generates a magnetic flux whose direction is parallel to the magnetic flux detection direction. For this reason, it is possible to avoid that the magnetic flux generated by the current flowing in the other current path has an influence on the detection operation of the magnetic flux detector as compared with the conventional magnetic flux detector installed in the current path. The current flowing through each current path can be detected with high accuracy and high sensitivity by a magnetic flux detector with a simple configuration without providing a magnetic shield or performing complicated calculation processing by a computer.
According to the current detection device having the configuration of (3) above, of the magnetic flux generated from the first current path and the magnetic flux generated from the second current path close to the first current path by the one magnetic flux detector. Both the magnetic fluxes in the two directions that coincide with the magnetic flux detection direction of the magnetic flux detector can be detected with high sensitivity. For this reason, the magnetic flux that does not coincide with one of the magnetic flux detection directions among the magnetic fluxes generated from the second current path does not affect the detected value of the magnetic flux generated from the first current path. Among the magnetic fluxes generated from the current path, the magnetic flux that does not coincide with the other magnetic flux detection direction does not affect the detected value of the magnetic flux generated from the second current path. For this reason, it is possible to detect the current flowing in each current path with high accuracy and high sensitivity by a magnetic flux detector with a simple configuration without providing a magnetic shield or performing complicated calculation processing by a computer as in the past. Can do.

  ADVANTAGE OF THE INVENTION According to this invention, with respect to the magnetic flux detector installed for every electric current path, the influence of the magnetic flux which generate | occur | produced by the electric current which flows into another adjacent electric current path is suppressed, and the electric current which flows into an electric current path can be detected accurately.

  The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by describing the best mode for carrying out the invention described below with reference to the accompanying drawings.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a current detection device according to the present invention will be described in detail with reference to the drawings. In addition, the case where the electric current which flows into the current path of each phase is detected using a magnetic flux detector is explained as an example of the current detection device of this embodiment using a drive circuit of a three-phase motor.

  Here, FIG. 1 is a circuit configuration diagram of a top view of the current detection device according to the embodiment of the present invention. 2 is a cross-sectional view of the circuit configuration diagram of FIG. 1 viewed from the II-II direction. FIG. 3 is a circuit diagram showing a three-phase motor drive circuit including the current detector of FIG.

  As shown in FIG. 3, the three-phase motor drive circuit includes a DC power source 1, an inverter 2, a three-phase (AC) motor 3, a motor control unit (microcomputer) 4, a drive circuit 5, and a current detection device. 6 are provided. Of these, the inverter 2 converts a DC voltage received from a DC power source such as a battery into a three-phase AC voltage of U phase, V phase, and W phase, and drives an AC three-phase motor at a predetermined control rotational speed. The inverter 2 also functions to return the electric power generated during the regenerative braking of the three-phase motor 3 to the DC power source 1.

  The three-phase motor 3 is driven by receiving the three-phase AC power output from the inverter 2, and is used as a drive source for an electric vehicle, for example. The three-phase motor 3 is provided with a resolver (rotation angle sensor) that detects rotation speed information for each of the U phase, the V phase, and the W layer. The motor control unit 4 is obtained from the rotational speed information of the three-phase motor detected by the resolver and the magnetic flux detection values of the first magnetic flux detector 6a and the second magnetic flux detector 6b constituting the current detection device 6. The drive circuit 5 is controlled based on the current values for the U phase, V phase, and W phase. The drive circuit 5 receives the control output from the motor control unit 4, controls the switch timing of the switching elements constituting the inverter 2, determines each phase current of the inverter 2 output, and sets the three-phase motor 3 to a predetermined rotational speed. To drive control.

  By the way, the magnetic flux detectors 6a and 6b and the current detection sensor main bodies 8a and 8b constituting the current detection device 6 are connected to each phase (U-phase, U-phase, etc.) connecting the inverter 2 and the three-phase motor 3 as shown in FIGS. V-phase and W-phase) flat plate current paths (bus bars) 7a, 7b, and 7c are provided in the vicinity. These current paths 7a, 7b, and 7c have the same cross-sectional shape and size, and are arranged in parallel in one plane at a predetermined distance. On the surface of the current detection sensor bodies 8a and 8b, a circuit for detecting a magnetic field (magnetic flux) (for example, a Hall element using a Hall effect, a Hall IC incorporating a Hall element and an amplifier circuit, a magnetoresistance using a magnetoresistance effect) The magnetic flux detectors 6a and 6b configured by (MR) elements, fluxgate (magnetic modulation) type magnetic sensors, etc.) are arranged. The magnetic flux detectors 6a and 6b are limited to two directions in which the magnetic flux detection directions capable of detecting the magnetic flux are orthogonal to each other (in FIG. 2, black lines extending from the magnetic flux detectors 6a and 6b as starting points). A solid arrow indicates the magnetic flux detection direction X, and a white arrow in a direction perpendicular to the black arrow indicates the magnetic flux detection direction Y), and the position where the magnetic flux detectors 6a and 6b are disposed. , It is possible to detect only the magnetic flux from each of the current paths 7a to 7c coinciding with the magnetic flux detection directions X and Y.

  As shown in FIG. 2, the magnetic flux detectors 6a and 6b arranged in the vicinity of the current paths 7a, 7b and 7c are respectively between the current path 7a and the current path 7b and between the current path 7b and the current path 7c. Thus, the current path 7b is disposed at the left and right target positions. More specifically, the first magnetic flux detector 6a is disposed at a position (intersection) P where magnetic field lines of magnetic fields generated from the first current path 7a and the second current path 7b intersect perpendicularly, and the second The magnetic flux detector 6b is arranged at a position (intersection) Q where magnetic field lines of magnetic fields generated from the second current path 7b and the third current path 7c intersect perpendicularly. The current paths 7a, 7b, and 7c are arranged at a constant distance L on the same plane.

  Further, the magnetic flux detectors 6a and 6b disposed at the intersections P and Q have the two orthogonal directions X and Y for detecting the magnetic field by the magnetic flux detectors 6a and 6b, respectively. In this arrangement, the direction of the magnetic field lines of the magnetic field generated from each of the current paths 7c coincides. In the embodiment of the present invention, the magnetic flux detectors 6a and 6b are installed on the surface in order to adjust the position where the magnetic flux detectors 6a and 6b are arranged and the direction in which the magnetic flux detectors 6a and 6b detect the magnetic flux. The shape of the current detection sensor bodies 8a and 8b to be changed is appropriately changed. Specifically, as shown in FIG. 2, the height from the current path in which the magnetic flux detectors 6a and 6b are arranged is adjusted by adjusting the thickness of the current detection sensor bodies 8a and 8b, or the current detection is performed. By chamfering the surfaces of the sensor bodies 8a and 8b, the direction in which the magnetic flux detectors 6a and 6b detect the magnetic flux is adjusted.

  By arranging the magnetic flux detectors 6a, 6b and the current paths 7a, 7b, 7c as described above, the magnetic flux detector 6a can only generate the magnetic flux generated from the current paths 7a, 7b, and the magnetic flux detector 6b can have the current paths 7b, Only the magnetic flux generated from 7c can be detected separately with high sensitivity. This will be described by taking the magnetic flux in the vicinity of the magnetic flux detectors 6a and 6b as an example.

  In the space where the current paths 7a, 7b, and 7c exist, there is a point (intersection) where magnetic field lines of magnetic fields generated from these current paths 7a, 7b, and 7c intersect. In FIG. 2, for example, two magnetic lines of magnetic force generated around the current path 7a are M1 and M2, and two magnetic lines of magnetic field generated around the current path 7b are M3, M4 and current. The magnetic field lines of the magnetic field generated around the path 7c are M5 and M6.

  Among these magnetic lines M1 to M6, the magnetic line M1 and the magnetic line M4 intersect perpendicularly at the intersection P, and the magnetic line M4 and the magnetic line M5 intersect perpendicularly at the intersection Q. It should be noted that other magnetic lines (not shown) generated by the current paths 7a and 7b also intersect perpendicularly at other points (not shown). And the magnetic flux detector 6a is installed in an intersection, and the two magnetic flux detection directions X and Y which this magnetic flux detector 6a orthogonally cross are made to correspond to the tangential direction of the magnetic force line M1 and the magnetic force line M4, respectively.

  Similarly, the magnetic flux detector 6b is installed at the intersection point Q, and the two perpendicular magnetic flux detection directions X and Y of the magnetic flux detector 6b are matched with the tangential directions of the magnetic field lines in the magnetic field M4 and the magnetic field M5. Thereby, the magnetic detector 6a detects the magnetic flux generated by the current path 7a and the current path 7b, respectively, and the magnetic detector 6b detects the magnetic flux generated by the current path 7b and the current path 7c, respectively.

  As described above, the magnetic flux detection directions of the magnetic flux detectors 6a and 6b coincide with the magnetic field lines (tangential directions) of the magnetic fields M1, M4, and M5 as described above, so that magnetic flux detection can be performed with high sensitivity. That is, since the magnetic flux detection directions of the magnetic flux detectors 6a and 6b are only two directions orthogonal to each other, they are not affected by the lines of magnetic force that do not coincide with these two directions, and therefore good detection sensitivity can be obtained.

  The magnetic detectors 6a and 6b detect the same magnetic field lines M4 in the magnetic field at symmetrical positions in the current path 7b. For this reason, the outputs (magnetic field strength) detected by the magnetic flux detectors 6a and 6b are the same. However, the magnetic flux detectors 6a and 6b may have individual characteristic variations based on external factors such as ambient temperature and other internal factors. In this case, it is desirable to compare the output values of the magnetic flux detectors 6a and 6b and reflect the comparison result (error) in the output value using a predetermined arithmetic expression. Thereby, magnetic flux detection and current detection can be performed with high accuracy.

  In the above description, the case where the magnetic flux detection direction of one magnetic flux detector (for example, magnetic flux detector 6a) is two directions (X and Y directions) orthogonal to each other has been described. As one direction (for example, X direction), it is good also as a structure which detects only the magnetic flux from one current path (for example, current path 7a) of the direction which corresponds to this one direction. In this case, magnetic flux from another current path (for example, current path 7b) in a direction (for example, Y direction) that does not coincide with the magnetic flux detection direction (X direction) of this one direction is not detected. Only the magnetic flux generated from the path (current path 7a) can be detected with high sensitivity.

  As described above, in the embodiment according to the present invention, one magnetic flux detector 6a is connected to the first current path 7a and the second current path by the current flowing through the first current path 7a and the second current path 7b. Arranged at positions where the magnetic fields generated from the current paths 7b are orthogonal to each other so that the direction of the magnetic field generated from the first current path 7a or the direction of the magnetic field generated from the second current path 7b coincides. Or the first magnetic flux detector 6a causes the magnetic fields generated from the first current path 7a and the second current path 7b to be orthogonal to each other by the current flowing through the first current path 7a and the second current path 7b, respectively. The first magnetic flux detection direction is made to coincide with the direction of the magnetic field generated from the first current path 7a at the first position P (intersection point), and the second magnetic flux detector 6b is connected to the first current path 7a and In the current flowing through the second current path 7b Thus, the magnetic field generated from each of the first current path 7a and the second current path 7b is generated from the second current path 7b at a second position (intersection point) Q different from the first position P. The magnetic flux detector 6a can detect the magnetic flux from at least one current path 7a that generates a magnetic flux whose direction is parallel to the magnetic flux detection direction. it can. For this reason, it is possible to avoid the magnetic flux generated by the current flowing in the other current path 7b from affecting the detection operation of the magnetic flux detector 6a with respect to the magnetic flux detector 6a installed in the current path 7a. As described above, the current flowing through each current path can be detected with high accuracy and high sensitivity by a magnetic flux detector with a simple configuration without providing a magnetic shield or performing complicated calculation processing by a computer.

  In the embodiment according to the present invention, one magnetic flux detector 6a is connected from the first current path 7a and the second current path 7b by the current flowing through the first current path 7a and the second current path 7b. By arranging the magnetic flux detection directions parallel to the direction of the magnetic field generated from the first current path 7a and the direction of the magnetic field generated from the second current path 7b at positions where the generated magnetic fields are orthogonal to each other. Of the magnetic flux generated from the first current path 7a and the magnetic flux generated from the second current path 7b close to the first current path 7a by the one magnetic flux detector 6a, the magnetic flux detection direction of the magnetic flux detector 6a. Only the magnetic fluxes in the two directions that coincide with each other can be detected with high sensitivity. Therefore, a magnetic flux that does not coincide with one of the magnetic flux detection directions among the magnetic fluxes generated from the second current path 7b does not affect the detected value of the magnetic flux generated from the first current path 7a. Of the magnetic fluxes generated from one current path 7a, the magnetic flux that does not coincide with the other magnetic flux detection direction does not affect the detected value of the magnetic flux generated from the second current path 7b.

  In the arrangement of the magnetic flux detectors 6a, 6b and the current paths 7a, 7b, 7c described above, the magnetic flux detector 7a of the current detection sensor main body 8a provided in the current path 7a is adjacent to the current path 7a. Although the influence of the magnetic field generated from the other current path 7b can be eliminated, the magnetic field generated from another current path 7c further adjacent to the other current path 7b on the side away from the current path 7a is detected by the magnetic flux. It is assumed that the device 7a is slightly affected. In order to eliminate such influences, the magnetic flux detection sensitivities of the magnetic flux detectors 6a and 6b are determined based on the interval between the current paths 7a, 7b and 7c arranged in parallel and the magnitude of the current flowing through these current paths 7a, 7b and 7c. It is preferable to set the sensitivity appropriately so that a certain magnetic flux detector 7a does not detect a magnetic field generated from another magnetic flux detector 7c adjacent to the current path 7b.

It is the circuit block diagram which looked at the electric current detection apparatus of embodiment which concerns on this invention from the top. It is sectional drawing which looked at the circuit block diagram of FIG. 1 from the II-II direction. FIG. 2 is a circuit diagram showing a three-phase motor driving circuit including the current detector of FIG. 1.

Explanation of symbols

1 DC power supply 2 Inverter 3 Three-phase motor 4 Motor controller (computer)
5 Drive circuit 6 Current detection device 6a, 6b Magnetic flux detector 7a, 7b, 7c Current path (wiring)
8a, 8b Current detection sensor body (wiring)
P, Q Intersection M1-M6 Magnetic field X, Y Magnetic flux detection direction

Claims (3)

A first current path;
A second current path;
One magnetic flux detector in which the magnetic flux detection direction for detecting the magnetic flux is limited to one direction;
A current detection sensor main body for detecting a current value of a current flowing in at least one of the first current path and the second current path based on the magnetic flux detected by the one magnetic flux detector;
With
The first current path and the second current path are flat-plate conductors and are arranged in a line on the same plane,
In the one magnetic flux detector, the directions of magnetic lines of magnetic force generated from the first current path and the second current path are orthogonal to each other by the current flowing through the first current path and the second current path, respectively. The magnetic flux detection direction is arranged at a position such that the direction of the magnetic field lines of the magnetic field generated from the first current path or the direction of the magnetic field lines of the magnetic field generated from the second current path matches.
A current detection device characterized by that. A first current path;
A second current path;
A first magnetic flux detector in which a magnetic flux detection direction for detecting magnetic flux is limited to one direction;
A second magnetic flux detector in which the magnetic flux detection direction for detecting the magnetic flux is limited to one direction;
A current detection sensor main body for detecting a current value of a current flowing through the first current path and the second current path based on the magnetic flux detected by the first magnetic flux detector and the second magnetic flux detector; ,
With
The first current path and the second current path are flat-plate conductors and are arranged in a line on the same plane,
In the first magnetic flux detector, magnetic field lines of magnetic fields generated from the first current path and the second current path, respectively, by currents flowing through the first current path and the second current path are orthogonal to each other. 1 is arranged so that the magnetic flux detection direction coincides with the direction of the magnetic field lines of the magnetic field generated from the first current path,
In the second magnetic flux detector, the magnetic field lines of the magnetic fields generated from the first current path and the second current path, respectively, by the current flowing through the first current path and the second current path are orthogonal to each other. The magnetic flux detection direction is arranged at a second position different from the first position so that the magnetic flux detection direction coincides with the direction of the magnetic force lines of the magnetic field generated from the second current path.
A current detection device characterized by that. A first current path;
A second current path;
One magnetic flux detector limited to two directions in which magnetic flux detection directions for detecting magnetic flux are orthogonal,
A current detection sensor main body for detecting a current value of a current flowing through each of the first current path and the second current path based on the magnetic flux detected by the one magnetic flux detector;
With
The first current path and the second current path are flat-plate conductors and are arranged in a line on the same plane,
The one magnetic flux detector is located at a position where magnetic field lines of magnetic fields generated from the first current path and the second current path are orthogonal to each other by currents flowing through the first current path and the second current path, respectively. The magnetic flux detection direction is arranged so as to match the direction of the magnetic field lines of the magnetic field generated from the first current path and the direction of the magnetic field lines of the magnetic field generated from the second current path.
A current detection device characterized by that.

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