Current sensor

Abstract

To provide a current sensor capable of increasing a ratio of a magnetic field by a bus bar current to external magnetic noise while achieving improvement in mass productivity and downsizing of a sensor.SOLUTION: A current sensor includes: a first magnetic sensor that measures magnetic field intensity in a first direction; a first bus bar that allows a current to flow in a second direction perpendicular to the first direction; and a second bus bar that allows a current to flow in a third direction perpendicular to the first direction. The first bus bar and the second bus bar are connected in series, and the first magnetic sensor is arranged at a position within a predetermined distance from the first bus bar and the second bus bar, and a current flowing in the first bus bar and a current flowing the second bus bar are different in direction. A value of the current flowing in the first bus bar and the second bus bar is measured on the basis of the magnetic filed intensity measured by the first magnetic sensor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a current sensor. [Background technology]

[0002] Patent Document 1 discloses a current sensor that detects magnetic flux generated by a current using a magnetic sensor having a magnetic impedance effect. In this current sensor, two magnetic sensors are arranged in positions where the absolute values ​​of the magnetic sensor outputs are equal and the polarities of the magnetic sensor outputs are opposite to each other with respect to the magnetic flux generated by the current, and the difference between the outputs of the two magnetic sensors is detected to cancel external noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-243766 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the current sensor disclosed in Patent Document 1, two magnetic sensors need to be placed in precise positions in order to increase the ratio of the magnetic field due to the busbar current to external magnetic field noise, but this poses the problem that it is difficult to improve mass productivity.

[0005] The present invention has been made in view of the problems inherent in the conventional techniques, and an object of the present invention is to provide a current sensor that can increase the ratio of the magnetic field caused by the busbar current to external magnetic field noise while improving mass productivity and miniaturizing the sensor. [Means for solving the problem]

[0006] A current sensor according to an aspect of the present invention includes a first magnetic sensor that measures a magnetic field strength in a first direction, a first bus bar that allows a current to flow in a second direction perpendicular to the first direction, and a second bus bar that allows a current to flow in a third direction perpendicular to the first direction. The first bus bar and the second bus bar are connected in series, and the first magnetic sensor is disposed at a position within a predetermined distance from the first bus bar and the second bus bar, and the current flowing through the first bus bar and the current flowing through the second bus bar are in different directions. The value of the current flowing through the first bus bar and the second bus bar is measured based on the magnetic field strength measured by the first magnetic sensor. Effect of the Invention

[0007] According to the present invention, it is possible to provide a current sensor that can increase the ratio of the magnetic field due to the busbar current to external magnetic field noise while improving mass productivity and realizing a miniaturized sensor. [Brief description of the drawings]

[0008] [Figure 1] 2A to 2C are diagrams illustrating the shape of a current sensor according to the first embodiment. [Diagram 2] 5 is a diagram showing a magnetic field strength distribution (in a direction parallel to the bus bar) in the current sensor according to the first embodiment. FIG. [Diagram 3] 4 is a diagram showing a magnetic field strength distribution (in a direction perpendicular to the busbar) in the current sensor according to the first embodiment. FIG. [Figure 4] 13A and 13B are diagrams illustrating a shape of a current sensor according to a second embodiment. [Diagram 5] 13 is a diagram showing a magnetic field strength distribution (in a direction parallel to the bus bar) in the current sensor according to the second embodiment. FIG. [Figure 6] 5A and 5B are diagrams illustrating the shape of a current sensor according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The current sensor according to the present embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios. In addition, in the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0010] [First embodiment] Fig. 1 is a diagram showing the shape of a current sensor according to a first embodiment. The current sensor 1 includes a first magnetic sensor SC1, a first bus bar 10, and a second bus bar 20. In Fig. 1, the first bus bar 10 and the second bus bar 20 are electrically connected in series via a third bus bar 30. In addition, the current sensor 1 may further include a second magnetic sensor SC2 at a position different from the first magnetic sensor SC1.

[0011] The first magnetic sensor SC1 and the second magnetic sensor SC2 measure the magnetic field strength in a first direction. Here, the "first direction" is the direction from the front side of the paper to the back side of the paper in Fig. 1. The first magnetic sensor SC1 and the second magnetic sensor SC2 are disposed at positions within a predetermined distance from the first bus bar 10 and the second bus bar 20. The positions at which the first magnetic sensor SC1 and the second magnetic sensor SC2 are disposed will be described later.

[0012] The first bus bar 10 extends in a second direction perpendicular to the first direction. The "second direction" is the direction from position P1 to position P2. As a result, the first bus bar 10 passes a current in the second direction perpendicular to the first direction.

[0013] The second bus bar 20 also extends in a third direction perpendicular to the first direction. The "third direction" is the direction from position P3 to position P4. As a result, the second bus bar 20 passes a current in the third direction perpendicular to the first direction.

[0014] Furthermore, the first bus bar 10, the second bus bar 20, and the third bus bar 30 may have a width direction in the first direction. That is, the first bus bar 10, the second bus bar 20, and the third bus bar 30 may be a plate-shaped conductive plate having a width direction in the first direction.

[0015] In the current sensor 1, a current flows through positions P1, P2, P3, and P4 in this order. Here, the second direction and the third direction may be anti-parallel. In other words, the third direction may be parallel to and opposite to the second direction.

[0016] When a current flows from position P1 to position P2 in the first busbar 10, a magnetic field in the first direction is generated at the positions of the first magnetic sensor SC1 and the second magnetic sensor SC2. When a current flows from position P3 to position P4 in the second busbar 20, a magnetic field in the first direction is generated at the positions of the first magnetic sensor SC1 and the second magnetic sensor SC2.

[0017] In addition, when a current flows in the third bus bar 30 from the position P2 to the position P3, a magnetic field in the first direction is generated at the positions of the first magnetic sensor SC1 and the second magnetic sensor SC2.

[0018] Since the second direction and the third direction are antiparallel, the second direction and the third direction are in different directions. That is, the current flowing through the first busbar 10 and the current flowing through the second busbar 20 are in different directions. Therefore, the magnetic field generated by the current flowing through the first busbar 10 and the magnetic field generated by the current flowing through the second busbar 20 are superimposed in a mutually enhancing direction at the positions of the first magnetic sensor SC1 and the second magnetic sensor SC2. As a result, the magnetic field strength measured by the first magnetic sensor SC1 and the second magnetic sensor SC2 is greater than the magnetic field strength generated only by the current flowing through the first busbar 10. Similarly, the magnetic field strength measured by the first magnetic sensor SC1 and the second magnetic sensor SC2 is greater than the magnetic field strength generated only by the current flowing through the second busbar 20.

[0019] The value of the current flowing through the first bus bar 10 and the second bus bar 20 can be measured based on the magnetic field strength measured by the first magnetic sensor SC1 and the second magnetic sensor SC2.

[0020] Next, the positions at which the first magnetic sensor SC1 and the second magnetic sensor SC2 are arranged will be described.

[0021] The first magnetic sensor SC1 and the second magnetic sensor SC2 may be disposed at the center in the width direction of the first bus bar 10 and the second bus bar 20. The first magnetic sensor SC1 may be disposed at a position equidistant from the surface of the first bus bar 10 and the surface of the second bus bar 20. Similarly, the second magnetic sensor SC2 may be disposed at a position equidistant from the surface of the first bus bar 10 and the surface of the second bus bar 20.

[0022] Fig. 2 is a diagram showing a magnetic field strength distribution (in a direction parallel to the busbars) in the current sensor according to the first embodiment. Fig. 2 shows how the magnetic field strength in the first direction at a position sandwiched between the first busbar 10 and the second busbar 20 changes depending on the distance from the third busbar 30, which is the portion where the first busbar 10 and the second busbar 20 are connected, to the position. Here, the "distance" is the distance measured along the first busbar 10 and the second busbar 20.

[0023] 1 and 2, the first magnetic sensor SC1 is disposed at a distance DS1, and the second magnetic sensor SC2 is disposed at a distance DS2. In this case, the first magnetic sensor SC1 measures a magnetic field strength HM1, and the second magnetic sensor SC2 measures a magnetic field strength HM2.

[0024] 2, as the distance DS1 and the distance DS2 increase, the magnetic field strength HM1 and the magnetic field strength HM2 tend to decrease, respectively. This shows that as the distance from the third bus bar 30 increases, the magnetic field generated by the current flowing through the third bus bar 30 becomes weaker at that position.

[0025] The first magnetic sensor SC1 and the second magnetic sensor SC2 are disposed in an area where the magnetic field generated by the superposition of the magnetic field caused by the current flowing through the first bus bar 10, the magnetic field caused by the current flowing through the second bus bar 20, and the magnetic field caused by the current flowing through the third bus bar 30 is equal to or greater than a predetermined intensity. This makes it possible to set the ratio of the intensity of the external magnetic field noise to the intensity of the magnetic field caused by the current flowing through the first bus bar 10, the second bus bar 20, and the third bus bar 30 to a predetermined reference value or less. As a result, the value of the current can be measured with high accuracy based on the magnetic field intensity measured by the first magnetic sensor SC1 and the second magnetic sensor SC2.

[0026] Therefore, the positions at which the first magnetic sensor SC1 and the second magnetic sensor SC2 are disposed may be determined based on the required measurement accuracy of the current value. More specifically, the higher the measurement accuracy of the current value, the smaller the "predetermined distance" may be set, and the first magnetic sensor SC1 and the second magnetic sensor SC2 may be disposed at a position within the predetermined distance from the first bus bar 10 and the second bus bar 20. Also, the first magnetic sensor SC1 and the second magnetic sensor SC2 may be disposed close to the third bus bar 30.

[0027] Fig. 3 is a diagram showing a magnetic field strength distribution (in a direction perpendicular to the busbars) in the current sensor according to the first embodiment. Fig. 3 shows how the magnetic field strength in the first direction at a position sandwiched between the first busbar 10 and the second busbar 20 changes depending on the distance from the second busbar 20 to the position. Here, the "distance" is the distance measured along a direction perpendicular to the direction in which the first busbar 10 and the second busbar 20 extend.

[0028] 1 and 3, the first magnetic sensor SC1 and the second magnetic sensor SC2 are disposed at a distance DH from each other, and the first bus bar 10 and the second bus bar 20 are disposed at a distance TH from each other.

[0029] 3, while the distance DH increases from 0 to half the distance TH, the magnetic field strength measured by the first magnetic sensor SC1 and the second magnetic sensor SC2 decreases, and while the distance DH increases from half the distance TH to the distance TH, the magnetic field strength measured by the first magnetic sensor SC1 and the second magnetic sensor SC2 increases.

[0030] Here, at the position where the distance DH is half the distance TH, the magnetic field intensity measured by the first magnetic sensor SC1 and the second magnetic sensor SC2 takes on a minimum value.

[0031] From the viewpoint of increasing the magnetic field strength measured by the first magnetic sensor SC1 and the second magnetic sensor SC2 as much as possible, it is preferable that the distance DH is 0 or the distance TH. However, when the distance DH is 0 or the distance TH, the magnetic field strength fluctuates significantly due to misalignment when arranging the first magnetic sensor SC1 and the second magnetic sensor SC2, which causes a decrease in measurement accuracy.

[0032] On the other hand, when the distance DH is half the distance TH, even if the first magnetic sensor SC1 and the second magnetic sensor SC2 are misaligned when they are arranged, the magnetic field strength does not fluctuate significantly, and the deterioration of the measurement accuracy is suppressed. In other words, the misalignment when the first magnetic sensor SC1 and the second magnetic sensor SC2 are allowed, and the mass productivity of the current sensor 1 is improved.

[0033] Therefore, the first magnetic sensor SC1 may be disposed at a position equidistant from the first bus bar 10 and the second bus bar 20. Similarly, the second magnetic sensor SC2 may be disposed at a position equidistant from the first bus bar 10 and the second bus bar 20.

[0034] Alternatively, the value of the current flowing through the first bus bar 10 and the second bus bar 20 may be measured based on the difference between the magnetic field intensity measured by the first magnetic sensor SC1 and the magnetic field intensity measured by the second magnetic sensor SC2. This makes it possible to measure the value of the current flowing through the first bus bar 10 and the second bus bar 20 while removing the influence of external magnetic field noise.

[0035] More specifically, the strength of external magnetic field noise is added to both the magnetic field strength measured by the first magnetic sensor SC1 and the magnetic field strength measured by the second magnetic sensor SC2. Therefore, when the magnetic field strength measured by the second magnetic sensor SC2 is subtracted from the magnetic field strength measured by the first magnetic sensor SC1, the contribution of the external magnetic field noise is eliminated.

[0036] On the other hand, since the first magnetic sensor SC1 and the second magnetic sensor SC2 are disposed at different positions, the contribution of the current flowing through the first bus bar 10, the second bus bar 20, and the third bus bar 30 remains in the difference in magnetic field strength. In particular, a difference occurs between the magnetic field strength measured by the first magnetic sensor SC1 and the magnetic field strength measured by the second magnetic sensor SC2 due to the distance to the third bus bar 30. Therefore, with respect to a portion where the first bus bar 10 and the second bus bar 20 are connected, the distance between the first bus bar 10 and the portion may be set to be different from the distance between the second magnetic sensor and the portion.

[0037] Furthermore, the distance between the first magnetic sensor SC1 and the first bus bar 10 may be the same as the distance between the second magnetic sensor SC2 and the first bus bar 10. This allows the first magnetic sensor SC1 and the second magnetic sensor SC2 to be installed with the same structure on the first bus bar 10, improving mass productivity.

[0038] [Second embodiment] Fig. 4 is a diagram showing the shape of a current sensor according to the second embodiment. In Fig. 4, the first bus bar 10 and the second bus bar 20 are electrically connected in series.

[0039] The first bus bar 10 extends in a second direction perpendicular to the first direction. The "second direction" is the direction from position P3 to position P4. As a result, the first bus bar 10 passes a current in the second direction perpendicular to the first direction.

[0040] The second bus bar 20 also extends in a third direction perpendicular to the first direction. The "third direction" is the direction from position P2 to position P3. As a result, the second bus bar 20 passes a current in the third direction perpendicular to the first direction.

[0041] In the current sensor 1, a current flows through positions P1, P2, P3, and P4 in this order. Unlike the first embodiment, the second direction and the third direction are not anti-parallel. The second direction and the third direction may be perpendicular to each other. As a result, the second direction and the third direction may be oriented in different directions.

[0042] The first magnetic sensor SC1 and the second magnetic sensor SC2 are disposed in an area formed by the first bus bar 10 and the second bus bar 20 where the angle between the first bus bar 10 and the second bus bar 20 is less than 180 degrees. Fig. 4 shows an example in which the first magnetic sensor SC1 and the second magnetic sensor SC2 are disposed in an area formed by the first bus bar 10 and the second bus bar 20 where the angle between the first bus bar 10 and the second bus bar 20 is 90 degrees.

[0043] The reason for placing the first bus bar 10 and the second bus bar 20 in an area where the angle between them is less than 180 degrees is to increase the magnetic field strength to be measured by superimposing the magnetic fields caused by the current flowing through the first bus bar 10 and the current flowing through the second bus bar 20.

[0044] Fig. 5 is a diagram showing a magnetic field strength distribution (in a direction parallel to the bus bar) in the current sensor according to the second embodiment. Fig. 5 shows how the magnetic field strength in the first direction changes depending on the distance from the second bus bar 20 to the position in question. Here, the "distance" is the distance to the second bus bar 20 measured along the first bus bar 10.

[0045] 4 and 5, the first magnetic sensor SC1 is disposed at a distance DS1, and the second magnetic sensor SC2 is disposed at a distance DS2. In this case, the first magnetic sensor SC1 measures a magnetic field strength HM1, and the second magnetic sensor SC2 measures a magnetic field strength HM2.

[0046] 5, as the distance DS1 and the distance DS2 increase, the magnetic field strength HM1 and the magnetic field strength HM2 tend to decrease, respectively. This shows that as the distance from the second bus bar 20 increases, the magnetic field generated by the current flowing through the second bus bar 20 becomes weaker at that position.

[0047] The first magnetic sensor SC1 and the second magnetic sensor SC2 are disposed in an area where the magnetic field generated by the superposition of the magnetic field caused by the current flowing through the first bus bar 10 and the magnetic field caused by the current flowing through the second bus bar 20 is equal to or greater than a predetermined strength. This makes it possible to set the ratio of the strength of the external magnetic field noise to the strength of the magnetic field caused by the current flowing through the first bus bar 10 and the second bus bar 20 to a predetermined reference value or less. As a result, the value of the current can be measured with high accuracy based on the magnetic field strength measured by the first magnetic sensor SC1 and the second magnetic sensor SC2.

[0048] Therefore, the positions of the first magnetic sensor SC1 and the second magnetic sensor SC2 may be determined based on the required measurement accuracy of the current value. More specifically, the higher the measurement accuracy of the current value, the smaller the "predetermined distance" may be set, and the first magnetic sensor SC1 and the second magnetic sensor SC2 may be disposed at positions within the predetermined distance from the first bus bar 10 and the second bus bar 20.

[0049] [Comparative Example] For comparison with the above-described embodiment, a comparative example will now be described. Fig. 6 is a diagram showing the shape of a current sensor 101 according to the comparative example.

[0050] In the current sensor 101, the first magnetic sensor SC1 is disposed at a position spaced a distance DH from the first bus bar 10. It is assumed that a current flows in the first bus bar 10 from a position P1 to a position P2.

[0051] In the current sensor 101, the magnetic field intensity measured by the first magnetic sensor SC1 is due only to the magnetic field generated by the current flowing through the first busbar 10. Therefore, the magnetic field intensity measured by the first magnetic sensor SC1 in the first and second embodiments is weaker.

[0052] This increases the ratio of the intensity of the external magnetic field noise to the intensity of the magnetic field caused by the current flowing through the first bus bar 10. As a result, in the comparative example, the measurement accuracy of the current value deteriorates.

[0053] [Effects of the embodiment] As described above in detail, the current sensor according to this embodiment includes a first magnetic sensor that measures a magnetic field strength in a first direction, a first bus bar that allows a current to flow in a second direction perpendicular to the first direction, and a second bus bar that allows a current to flow in a third direction perpendicular to the first direction. The first bus bar and the second bus bar are connected in series, the first magnetic sensor is disposed at a position within a predetermined distance from the first bus bar and the second bus bar, and the current flowing through the first bus bar and the current flowing through the second bus bar are in different directions. The value of the current flowing through the first bus bar and the second bus bar is measured based on the magnetic field strength measured by the first magnetic sensor.

[0054] This makes it possible to increase the ratio of the magnetic field caused by the bus bar current to external magnetic field noise while improving mass productivity and miniaturizing the sensor, thereby improving the measurement accuracy of the bus bar current.

[0055] In the current sensor according to the present embodiment, the first bus bar and the second bus bar may have a width direction in the first direction. This allows a current to flow reliably through the first bus bar and the second bus bar. Furthermore, a magnetic field can be reliably generated at the position where the first magnetic sensor is disposed by the current flowing through the first bus bar and the second bus bar. As a result, the measurement accuracy of the bus bar current can be improved.

[0056] Furthermore, in the current sensor according to this embodiment, the first magnetic sensor may be disposed at a position equidistant from the first bus bar and the second bus bar. This suppresses the gradient of the magnetic field strength near the first magnetic sensor. Therefore, even if the first magnetic sensor is misaligned when it is disposed, the magnetic field strength does not vary significantly, and a decrease in measurement accuracy is suppressed. In other words, misalignment when the first magnetic sensor is disposed is permitted, and mass productivity of the current sensor is improved.

[0057] In the current sensor according to this embodiment, the second direction and the third direction may be anti-parallel. This increases the effect of superposition of the magnetic field generated by the current flowing through the first bus bar and the magnetic field generated by the current flowing through the second bus bar near the first magnetic sensor. This increases the magnetic field strength measured by the first magnetic sensor. This increases the ratio of the magnetic field generated by the bus bar current to external magnetic field noise, thereby improving the measurement accuracy of the bus bar current.

[0058] Furthermore, in the current sensor according to this embodiment, the second direction and the third direction may be perpendicular to each other. This increases the effect of the superposition of the magnetic field generated by the current flowing through the first bus bar and the magnetic field generated by the current flowing through the second bus bar near the first magnetic sensor. This increases the magnetic field strength measured by the first magnetic sensor. This increases the ratio of the magnetic field generated by the bus bar current to external magnetic field noise, thereby improving the measurement accuracy of the bus bar current.

[0059] Moreover, the current sensor according to the present embodiment may further include a second magnetic sensor arranged at a position different from the first magnetic sensor for measuring the magnetic field strength in the first direction. The current value flowing through the first bus bar and the second bus bar may be measured based on the difference between the magnetic field strength measured by the first magnetic sensor and the magnetic field strength measured by the second magnetic sensor. This makes it possible to measure the current value flowing through the first bus bar and the second bus bar while removing the influence of external magnetic field noise. This improves the measurement accuracy of the bus bar current.

[0060] Furthermore, in the current sensor according to the present embodiment, the distance between the first magnetic sensor and the portion where the first bus bar and the second bus bar are connected may be different from the distance between the second magnetic sensor and the portion. As a result, the contribution of the bus bar current remains in the difference in the measured magnetic field strength. As a result, it is possible to measure the value of the current flowing through the first bus bar and the second bus bar while removing the influence of external magnetic field noise. Therefore, it is possible to improve the measurement accuracy of the bus bar current.

[0061] In the current sensor according to the present embodiment, the distance between the first magnetic sensor and the first bus bar may be the same as the distance between the second magnetic sensor and the first bus bar. This allows the first magnetic sensor and the second magnetic sensor to be installed on the first bus bar with the same structure, improving mass productivity of the current sensor.

[0062] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0063] 1 Current Sensor 10 First bus bar 20 2nd bus bar 30 3rd bus bar SC1 First magnetic sensor SC2 Second magnetic sensor

Claims

1. a first magnetic sensor for measuring a magnetic field strength in a first direction; a first bus bar that allows a current to flow in a second direction perpendicular to the first direction; a second bus bar that allows a current to flow in a third direction perpendicular to the first direction; A current sensor comprising: the first bus bar and the second bus bar are connected in series, the first magnetic sensor is disposed at a position within a predetermined distance from the first bus bar and the second bus bar; a current flowing through the first bus bar and a current flowing through the second bus bar are in different directions; measuring values ​​of currents flowing through the first bus bar and the second bus bar based on the magnetic field intensity measured by the first magnetic sensor; Current sensor.

2. The current sensor according to claim 1 , wherein the first bus bar and the second bus bar have a width direction in the first direction.

3. The current sensor according to claim 1 , wherein the first magnetic sensor is disposed at a position equidistant from the first bus bar and the second bus bar.

4. The current sensor of claim 1 , wherein the second direction and the third direction are anti-parallel.

5. The current sensor of claim 1 , wherein the second direction and the third direction are orthogonal.

6. a second magnetic sensor that measures a magnetic field strength in the first direction and is disposed at a position different from the first magnetic sensor; measuring a value of a current flowing through the first bus bar and the second bus bar based on a difference between a magnetic field intensity measured by the first magnetic sensor and a magnetic field intensity measured by the second magnetic sensor; A current sensor according to any one of claims 1 to 5.

7. With respect to a portion where the first bus bar and the second bus bar are connected, The current sensor of claim 6 , wherein a distance between the first magnetic sensor and the portion is different from a distance between the second magnetic sensor and the portion.

8. The current sensor according to claim 6 , wherein a distance between the first magnetic sensor and the first bus bar is the same as a distance between the second magnetic sensor and the first bus bar.

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