JP2015215166A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor configured to prevent a measurement error of the amount of current to be measured, even if there is a source which generates a magnetic flux different from a magnetic flux generated by the current to be measured.SOLUTION: A current sensor 1 includes: an annular core 11 having a magnetic flux measurement gap 111 and at least one magnetic saturation prevention gap 112; and a hall element 13 arranged in the magnetic flux measurement gap 111 to measure a magnetic flux generated by a bus bar 50. In a first path formed from an entrance part of a magnetic flux leaked from other than the bus bar 50 to the magnetic measurement gap 111 along the annular core 11, and a second path formed from the entrance part to the magnetic measurement gap in a direction opposite the first path, the total widths of the magnetic saturation prevention gaps 112 in both paths are the same.

Description

  The present invention relates to a current sensor, and more particularly to a current sensor having an annular core including a magnetic flux measurement gap and a magnetic saturation prevention gap.

  As a current sensor for measuring a current flowing in a current path such as a bus bar, a sensor using a magnetic body (core) arranged so as to surround a current path to be measured is known. In such a current sensor, a gap (gap) is formed in a part of the core, and a magnetosensitive element such as a Hall element is provided in the gap. In this current sensor, the core collects the magnetic flux induced by the current flowing through the current path, and the magnetosensitive element provided in the gap measures the magnetic flux density, thereby measuring the amount of current flowing through the current path.

  Further, there is a current sensor having a configuration in which a gap is further added in addition to a gap for providing a magnetosensitive element. For example, Patent Document 1 discloses a configuration in which a gap for preventing magnetic saturation (hereinafter referred to as a magnetic saturation prevention gap) is added in order to prevent a current from being accurately detected due to magnetic saturation in the core. doing.

JP 2006-071456 A

  If a bus bar other than the bus bar to be measured is arranged near the current sensor, it is conceivable that the magnetic flux leaking from the bus bar reaches the magnetosensitive element via the core of the current sensor. At this time, the magnitude of the magnetic flux is larger between the leakage magnetic flux that reaches the magnetic sensing element through the path through the magnetic saturation prevention gap and the leakage magnetic flux that reaches the magnetic sensing element through the reverse path not through the magnetic saturation prevention gap. A difference arises. For this reason, the magnetic flux in the circumferential direction of the core remains in the magnetosensitive element portion, which may cause a measurement error in the current measurement of the bus bar to be measured.

  This point will be described more specifically with reference to the drawings. First, the influence of leakage magnetic flux in a core (single gap core) having only one gap (hereinafter referred to as a magnetic flux measurement gap) where a magnetosensitive element is provided and having no magnetic saturation prevention gap will be described. Next, the influence of leakage flux in a core (double gap core) having one magnetic saturation prevention gap in addition to the magnetic flux measurement gap will be described. As will be described below, the influence of leakage magnetic flux on current measurement is greater in a core having a magnetic saturation prevention gap than in a core having no magnetic saturation prevention gap.

  FIG. 8 is a diagram for explaining the influence of leakage magnetic flux caused by adjacent bus bars in a core that does not have a magnetic saturation prevention gap. Here, FIG. 8A is a front view of the current sensors 10a and 10b formed of a core having no magnetic saturation prevention gap, and cross sections are drawn for the bus bars 60a and 60b to be measured. . In the example shown in FIG. 8A, current sensors 10a and 10b are provided in each of two bus bars 60a and 60b adjacent to each other. Each of the current sensors 10a and 10b has cores 200a and 200b, and magnetic flux measurement gaps 210a and 210b are provided on the cores. Magnetic sensitive elements 300a and 300b are provided in the gap.

  FIG. 8B is a schematic diagram showing a state of leakage magnetic flux entering the current sensor 10a when a current is passed through the bus bar 60b. In addition, in FIG.8 (b), the arrow has shown the leakage magnetic flux. The magnetic flux generated by the right bus bar 60b is collected by the right core 200b, but a part of the magnetic flux leaks to the left core 200a. The leaked magnetic flux enters from the right end of the left core 200a (the end of the core 200a on the side of the adjacent bus bar 60b), and is divided vertically from the entry portion, and passes through the core 200a counterclockwise. Follow the clockwise direction and merge again at the magnetosensitive element 300a.

  FIG. 8C is a schematic diagram illustrating the result of CAE (Computer Aided Engineering) analysis on the state of leakage magnetic flux entering the current sensor 10a when a current is passed through the bus bar 60b, and in the vicinity of the magnetosensitive element 300a. The magnetic flux vector is drawn with a dashed arrow. Note that the solid line arrow extending upward from the magnetic sensing element 300a is a composite vector of magnetic flux vectors indicated by the broken line arrow.

  As shown in FIG. 8C, since the magnetic flux vector reaching the magnetic flux measurement gap 210a from the right side and the magnetic flux vector reaching the magnetic flux measurement gap 210a from the left side are substantially the same size, these combined vectors are The vector extends in the vertical direction (y-axis direction in the drawing) in the magnetosensitive element 300a. That is, since the vector components in the circumferential direction of the core, which is the magnetic sensing direction (x-axis direction in the figure) of the magnetic sensing element 300a cancel each other, no leakage magnetic flux is measured. Strictly speaking, since the magnetic path length differs between the clockwise path and the counterclockwise path in FIG. 8B, there is a difference in magnetic resistance, and the measurement of the leakage magnetic flux in the magnetosensitive element 300a is zero. Although not limited, this is a negligible effect.

  Next, the influence of the leakage magnetic flux in the core having the magnetic saturation prevention gap will be described. FIG. 9 is a diagram illustrating the influence of leakage magnetic flux caused by adjacent bus bars in a core having a magnetic saturation prevention gap. Here, FIG. 9A is a front view of the current sensors 20a and 20b formed of a core having a magnetic saturation prevention gap, and a cross section is drawn for each of the measurement target bus bars 61a and 61b. In the example shown in FIG. 9A, as in FIG. 8A, current sensors 20a and 20b are provided in two bus bars 61a and 61b adjacent to each other. Each current sensor 20a, 20b has a core 201a, 201b. Magnetic flux measuring gaps 211a and 211b are provided on the upper portions of the cores 201a and 201b, respectively. Magnetic saturation prevention gaps 212a and 212b are provided below the cores 201a and 201b, respectively. Magnetic sensing elements 301a and 301b are provided in the upper magnetic flux measurement gaps 211a and 211b.

  FIG. 9B is a schematic diagram showing the state of leakage magnetic flux that enters the current sensor 20a when a current is passed through the bus bar 61b. In addition, in FIG.9 (b), the arrow has shown the leakage magnetic flux. The magnetic flux generated by the right bus bar 61b is collected by the right core 201b, but a part of the magnetic flux leaks to the left core 201a as in the above example. The leaked magnetic flux enters from the right end of the left core 201a (the end of the core 201a on the side of the adjacent bus bar 61b), and is divided vertically from the entry portion, and passes through the core 201a in a counterclockwise direction. Following the clockwise direction, the magnetic sensing element 301a joins again.

  FIG. 9C is a schematic diagram illustrating the result of CAE analysis on the state of leakage magnetic flux entering the current sensor 20a when a current is passed through the bus bar 61b. The magnetic flux vector in the vicinity of the magnetosensitive element 301a is indicated by a broken line. It is drawn with an arrow. In addition, the solid line arrow extending upward from the magnetic sensing element 301a illustrates the combined vector of the magnetic flux vectors indicated by the broken line arrow.

  As shown in FIG. 9 (b), the leakage magnetic flux that has entered from the right end of the core 201a is divided into a clockwise path and a counterclockwise path and merges at the magnetosensitive element 301a portion. In contrast to reaching the magnetosensitive element 301a across the saturation prevention gap 212a provided at the lower part of 201a, the counterclockwise magnetic flux reaches the magnetosensitive element 301a without straddling the saturation prevention gap 212a. Since the gap portion has a remarkably higher magnetic resistance than the magnetic portion, the magnetic flux density decreases when the gap portion is straddled. For this reason, there is a difference in magnetic flux density depending on the path.

  For this reason, as shown in FIG. 9C, unlike the example shown in FIG. 8C, the magnetic flux density of the magnetic flux reaching the magnetic flux measurement gap 211a from the right side is changed to the magnetic flux measurement gap 211a from the left side. It is larger than the magnetic flux density of the reaching magnetic flux, and the components of the magnetic flux in the X-axis direction are not canceled out. For this reason, in the magnetosensitive element 301a part, the magnetic flux composite vector is inclined leftward in the figure. Therefore, a magnetic flux remains in the circumferential direction of the core, which is the magnetic sensing direction (x-axis direction in the drawing) of the magnetic sensing element 301a, and the leakage magnetic flux is detected by the magnetic sensing element 301a. This is considered to cause a measurement error of the current amount.

  The present invention has been made against the background described above, and suppresses measurement errors in the amount of current to be measured even when there is a source of magnetic flux other than the magnetic flux generated by the current to be measured. An object of the present invention is to provide a current sensor capable of

A current sensor according to the present invention includes an annular core including a magnetic flux measurement gap and at least one magnetic saturation prevention gap, and a magnetosensitive element provided in the magnetic flux measurement gap and measuring a magnetic flux generated by a current path. A current sensor having a first path that reaches the magnetic measurement gap along the annular core from an entrance portion of leakage magnetic flux from other than the current path, and the first path in a direction opposite to the first path In the second path that reaches the magnetic measurement gap from the entry portion, the total width of the magnetic saturation prevention gap that passes through each path is the same.

  According to such a configuration, the first path and the second path can have the same gap width through which the leakage magnetic flux passes before reaching the magnetosensitive element. The difference in resistance can be suppressed. Therefore, measurement errors due to leakage magnetic flux can be suppressed.

  According to the present invention, it is possible to provide a current sensor that can suppress a measurement error of a current amount of a current to be measured even when there is a source of magnetic flux other than the magnetic flux generated by the current to be measured. .

1 is a perspective view of a current sensor 1 according to a first embodiment. 1 is a front view of a current sensor 1 according to a first embodiment. FIG. 2 is a perspective view of an internal circuit 3 of the inverter according to the first embodiment. FIG. 3 is a front view of an internal circuit 3 of the inverter according to the first embodiment. It is a figure explaining the leakage magnetic flux in the current sensor 1a concerning Embodiment 1, (a) is a schematic diagram which shows the mode of the leakage magnetic flux which approachs into the current sensor 1a, (b) illustrates the result by CAE analysis. FIG. FIG. 6 is a front view of a current sensor 2 according to a second embodiment. It is a schematic diagram shown about the internal circuit 3 of the inverter at the time of using the current sensor 2 concerning Embodiment 2. FIG. It is a figure explaining the influence of the leakage magnetic flux in case it does not have a magnetic saturation prevention gap, (a) is a front view of current sensor 10a, 10b, (b) is a schematic diagram which shows the mode of leakage magnetic flux. (C) is the schematic diagram which illustrated the result by CAE analysis. It is a figure explaining the influence of the leakage magnetic flux in the case of having a magnetic saturation prevention gap, (a) is a front view of the current sensors 20a, 20b, (b) is a schematic diagram showing the state of the leakage magnetic flux, (C) is the schematic diagram which illustrated the result by CAE analysis.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a current sensor 1 according to the first embodiment. FIG. 2 is a front view of the current sensor 1 according to the first embodiment. 1 and 2, in addition to the current sensor 1, a bus bar 50 that is a current path to be measured is illustrated.

The current sensor 1 has an annular core 11 and a hall element 13. The current sensor 1 is provided so as to surround the bus bar 50.
The annular core 11 includes a magnetic flux measurement gap 111, a magnetic saturation prevention gap 112, and magnetic body portions 113 and 114. The magnetic flux measuring gap 111 is provided on the upper portion of the annular core 11. In addition, the magnetic saturation prevention gap 112 is provided in a portion where the leakage magnetic flux enters the annular core 11. Here, the leakage magnetic flux refers to other magnetic flux due to other than the current flowing in the current path to be measured. Specifically, for example, the portion of the circumferential direction of the annular core 11 closest to the generation source of the magnetic flux other than the magnetic flux generated by the current to be measured corresponds to the portion where the leakage magnetic flux enters.
As described above, the annular core 11 includes a magnetic part and two gap parts, and the magnetic part and the gap part form an annular shape.

  The hall element 13 is a magnetosensitive element disposed in the magnetic flux measurement gap 111 and measures the magnetic flux component in the circumferential direction of the annular core 11.

  In the current sensor 1, the leakage magnetic flux that has entered the annular core 11 reaches the hall element 13 in two paths. That is, the first path that travels upward from the entry portion and reaches the hall element 13 via the annular core 11 (via the magnetic body portion 113) counterclockwise is opposite to the first path. As a route around, the leakage magnetic flux is transferred to the second route reaching the Hall element 13 via the annular core 11 (through the magnetic body portion 114) in the clockwise direction from the entry portion downward. It will be divided.

  At this time, the magnetic resistance of the magnetic path is equal between the first path and the second path. This is because the difference in the magnetic resistance for each path depends on the gap that passes through the path, and the width of the gap that passes through the first path and the second path are the same. Note that the width of the gap refers to the length of the gap in the circumferential direction of the annular core 11. Assuming that the entrance position of the leakage magnetic flux in the annular core 11 is the center in the circumferential direction of the magnetic saturation prevention gap 112, the gap in each path to the magnetic flux measurement gap 111 when the width of the magnetic saturation prevention gap 112 is d. The widths are each d / 2, and both are the same. Note that when the magnetic flux measurement gap 111 is not included in the starting points of both paths (that is, the starting point of the first path is a portion facing the magnetic saturation prevention gap 112 in the magnetic body portion 113, and the second path In the case where the starting point of the path is regarded as a part facing the magnetic saturation prevention gap 112 in the magnetic body portion 114), the gap width in each path to the magnetic flux measurement gap 111 is 0 and both are the same. .

  For this reason, the leakage flux vectors in the circumferential direction (magnetic sensing direction) of the annular core 11 cancel each other at the position of the Hall element 13, and measurement errors due to leakage flux in current measurement of the bus bar 50 can be suppressed.

  Next, a specific application example of the above-described current sensor 1 will be described. FIG. 3 is a perspective view showing a part of the internal circuit 3 of the inverter for energizing the motor. FIG. 4 is a front view of the internal circuit 3 of the inverter shown in FIG. In the internal circuit 3 of the inverter shown in FIGS. 3 and 4, the bus bar 51a and the bus bar 51b are provided adjacent to each other. The bus bars 51a and 51b are provided with the above-described current sensors 1, respectively. Hereinafter, the reference symbol a is attached to the current sensor 1 that measures the amount of current flowing through the bus bar 51a and its constituent elements, and the reference symbol b is attached to the current sensor 1 that measures the amount of current flowing through the bus bar 51b and the constituent elements thereof. Distinguish.

  Here, as shown in FIG. 3, the current sensors 1a and 1b are disposed adjacent to each other at a position where the bus bar 51a and the bus bar 51b run side by side. More specifically, the current sensors 1a and 1b are installed so as to surround the bus bars 51a and 51b, respectively, and are provided so that their directions are symmetrical to each other. That is, in the current sensor 1a, the magnetic flux measuring gap 111a is provided on the upper portion of the annular core 11a, and the magnetic saturation preventing gap 112a is provided on the portion facing the bus bar 51b (the right end portion of the annular core 11a). On the other hand, in the current sensor 1b, the magnetic flux measurement gap 111b is provided on the upper portion of the annular core 11b, and the magnetic saturation prevention gap 112b is provided on the portion facing the bus bar 51a (the left end portion of the annular core 11b). .

  More specifically, in the application example shown in FIG. 3 and FIG. 4, the center of the annular core 11 a and the source of the leakage magnetic flux are provided in order to provide the magnetic saturation prevention gap 112 a in the leakage flux entrance portion of the annular core 11 a. A magnetic saturation prevention gap 112a is provided at a portion where a line segment connecting adjacent bus bars 51b in the annular core 11b intersects the annular core 11a. Similarly, in the application example shown in FIGS. 3 and 4, the line segment connecting the center of the annular core 11b and the adjacent bus bar 51a in the annular core 11a that is the source of leakage magnetic flux is connected to the annular core 11b. A magnetic saturation prevention gap 112b is provided at the intersecting portion.

  With the above configuration, in the current sensor 1a, the annular core 11a collects the magnetic flux due to the current flowing through the bus bar 51a, and the Hall element 13a detects the magnetic flux density to measure the amount of current flowing through the bus bar 51a. Similarly, in the current sensor 1b, the annular core 11b collects magnetic flux due to the current flowing through the bus bar 51b, and the Hall element 13b detects the magnetic flux density to measure the amount of current flowing through the bus bar 51b.

  At this time, since the bus bars 51a and 51b are close to each other, the annular core 11a collects not only the magnetic flux due to the current flowing through the bus bar 51a but also the magnetic flux due to the current flowing through the bus bar 51b. Further, the annular core 11b collects not only the magnetic flux due to the current flowing through the bus bar 51b but also the magnetic flux due to the current flowing through the bus bar 51a.

However, in the application example shown in FIGS. 3 and 4 as described below, current measurement errors due to leakage magnetic flux can be suppressed.
Fig.5 (a) is a schematic diagram shown about the state of the leakage magnetic flux which approachs into the current sensor 1a, when an electric current is sent through the bus-bar 51b. In FIG. 5A, an arrow indicates a leakage magnetic flux.

  FIG. 5B is a schematic diagram illustrating the result of CAE analysis regarding the state of the leakage magnetic flux that enters the current sensor 1a when a current is passed through the bus bar 51b. The magnetic flux vector in the vicinity of the Hall element 13a is indicated by a dashed arrow. It is drawn with. A solid arrow extending upward from the Hall element 13a illustrates a combined vector of magnetic flux vectors indicated by a broken line arrow.

  As shown in FIG. 5 (a), the leakage magnetic flux generated in the bus bar 51b enters from the magnetic saturation prevention gap 112a portion of the annular core 11a, is divided into upper and lower parts, and each first turns counterclockwise around the annular core 11a. And the second path that rotates clockwise around the annular core 11a and merges again at the Hall element 13a portion. At that time, the widths of the gaps through which the leakage magnetic flux passes are the same in the first path and the second path, and there is no difference in magnetoresistance due to the gaps in both paths. For this reason, as shown in FIG. 5B, the magnetic flux vector reaching the magnetic flux measurement gap from the right side and the magnetic flux vector reaching the magnetic flux measurement gap from the left side have substantially the same size. Therefore, these combined vectors are vectors extending in the vertical direction (y-axis direction in the figure) while canceling out the magnetosensitive direction (x-axis direction in the figure) in the Hall element 13a portion. Therefore, the leakage flux is not measured in the Hall element 13a, and the occurrence of measurement error is suppressed. Similarly, the leakage flux is not measured in the Hall element 13b, and the occurrence of measurement errors is suppressed.

  The current sensor 1 that can suppress the measurement error has been described above. However, according to the current sensor 1, it is easy to reduce the size of the current sensor while suppressing the measurement error. As shown in FIG. 3 and FIG. 4, when it is necessary to provide a current sensor in a narrow area, the current sensor itself must be downsized. When the current sensor is downsized, the downsizing of the core may become a bottleneck. For example, in the case of a single gap core current sensor as shown in FIG. 8, the influence of the leakage magnetic flux on the current measurement is smaller than that in the case where the magnetic saturation prevention gap is provided as described above. However, if the core itself is simply reduced, magnetic saturation occurs and the linearity of the BH characteristic (magnetization characteristic) is lost. For this reason, the current measurement accuracy deteriorates.

  On the other hand, as shown in JP 2014-6161 A, if the gap width of the magnetic flux measurement gap is increased, the linearity of the BH characteristic is maintained, but the gap width is larger than the core width. Can not do it. Therefore, as shown in Japanese Patent Application Laid-Open No. 2013-200140, by providing a plurality of gaps in the core, the total length of the gaps on the magnetic path is increased, the core is downsized, and the BH characteristic line is straightened. It is possible to balance the securing of sex.

  However, this still has problems. That is, even if a plurality of gaps are provided in the core in this way, if a source of magnetic flux other than the magnetic flux generated by the current to be measured is close to the current sensor, it is affected by the influence of the other magnetic flux. Measurement error may occur. On the other hand, the current sensor 1 can be reduced in size while preventing the measurement accuracy from deteriorating because the measurement error due to the influence of other magnetic fluxes can be suppressed as described above.

Embodiment 2
FIG. 6 is a front view of the current sensor 2 according to the second embodiment. In FIG. 6, in addition to the current sensor 2, a cross section of the bus bar 52, which is a current path to be measured, is illustrated. The current sensor 1 according to the first embodiment shows an example in which the magnetic saturation prevention gap is one. However, in the second embodiment, it is shown in the first embodiment in that it has a plurality of magnetic saturation prevention gaps. Different from the current sensor 1. In the current sensor 2, the same components as those of the current sensor 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The current sensor 2 includes one magnetic flux measurement gap 111 and n (where n is an integer of 3 or more) magnetic saturation prevention gaps 121_1 to 121_n (hereinafter may be collectively referred to as reference numeral 121). An annular core 12 is provided. Here, any one of the n magnetic saturation prevention gaps 121 is provided at the portion where the leakage magnetic flux enters the annular core 12, as in the current sensor 1.

  In addition, at least one gap for preventing magnetic saturation is present on the first path that reaches the hall element 13 via the annular core 12 in the counterclockwise direction from the portion where the leakage magnetic flux enters the annular core 12. 121 is provided, and at least one for preventing magnetic saturation is also provided on the second path that reaches the hall element 13 via the annular core 12 in the clockwise direction from the portion where the leakage magnetic flux enters downward. A gap 121 is provided.

  Here, it is assumed that the magnetic saturation prevention gap 121_k (wherein an integer satisfying 1 <k <n) is provided at the portion where the leakage magnetic flux enters the annular core 12, and the magnetic saturation prevention gaps 121_1 to 121_k−1. Are provided on the first path, and the magnetic saturation prevention gaps 121_k + 1 to 121_n are provided on the second path.

  Here, the magnetic saturation prevention gap 121 provided in the annular core 12 is provided so as to satisfy the following relationship. That is, the sum of the gap widths of the magnetic saturation prevention gaps 121_1 to 121_k−1 provided on the first path and the gap width of the magnetic saturation prevention gaps 121_k + 1 to 121_n provided on the second path. Is the same as the sum of

  Note that the magnetic saturation prevention gap 121 provided in the annular core 12 only needs to have the same total width of the gap on the first path and the total width of the gap on the second path. Different numbers of magnetic saturation prevention gaps 121 may be provided in the second path and the second path.

  In the current sensor 2, the leakage magnetic flux that has entered the annular core 12 reaches the hall element 13 by being divided into a first path and a second path. At this time, since the sum of the gap widths is the same in the first path and the second path, the magnetic resistances of both magnetic paths are equal. For this reason, the leakage flux vectors in the circumferential direction (x-axis direction in the figure), which is the magnetic sensing direction of the annular core 12, cancel each other out at the position of the Hall element 13, resulting in a measurement error in current measurement of the bus bar 52 due to the leakage flux. Can be suppressed.

  Next, a specific application example of the current sensor 2 will be described. Here, an application example in which the current sensor 1 is replaced with the current sensor 2 including three magnetic saturation prevention gaps 121 in the internal circuit 3 of the inverter shown in FIGS. 3 and 4 will be described. FIG. 7 is a schematic diagram showing a state where two current sensors 2 are used instead of the two current sensors 1 in the internal circuit 3 of the inverter. Hereinafter, the reference symbol a is attached to the current sensor 2 that measures the amount of current flowing through the bus bar 51a and its constituent elements, and the reference symbol b is attached to the current sensor 2 that measures the amount of current flowing through the bus bar 51b. Distinguish.

  Also in this application example, as in the application example of the current sensor 1 shown in FIGS. 3 and 4, the current sensors 2 a and 2 b are oriented at positions where the bus bar 51 a and the bus bar 51 b run side by side, at positions adjacent to each other. They are provided so as to be symmetrical with each other. That is, in the current sensor 2a, the magnetic flux measurement gap 111a is provided on the upper portion of the annular core 12a, and the magnetic saturation prevention gap 121_2a is provided on the portion facing the bus bar 51b (the right end portion of the annular core 12a). On the other hand, in the current sensor 2b, the magnetic flux measurement gap 111b is provided on the upper portion of the annular core 12b, and the magnetic saturation prevention gap 121_2b is provided on the portion facing the bus bar 51a (the left end portion of the annular core 12b). .

  A magnetic saturation prevention gap 121_1a is provided on the first path of the annular core 12a, and a magnetic saturation prevention gap 121_3a is provided on the second path of the annular core 12a. Further, a magnetic saturation prevention gap 121_1b is provided on the first path of the annular core 12b, and a magnetic saturation prevention gap 121_3b is provided on the second path of the annular core 12b.

  Here, the gap width of the magnetic saturation prevention gap 121_1a and the gap width of the magnetic saturation prevention gap 121_3a are set to be the same. For this reason, in the current sensor 2a, the first path and the second path have the same sum of gap widths, so that measurement errors due to leakage magnetic flux in the current measurement of the bus bar 51a can be suppressed. The gap width of the magnetic saturation prevention gap 121_1b and the gap width of the magnetic saturation prevention gap 121_3b are set to be the same. For this reason, in the current sensor 2b, the first path and the second path have the same total gap width, so that measurement errors due to leakage magnetic flux in current measurement of the bus bar 51b can be suppressed.

  The application example of the current sensor 2 has been described with reference to FIG. 7, but the current sensors 2 a and 2 b do not necessarily have the same configuration. For example, in the example shown in FIG. 7, the magnetic saturation prevention gaps 121_1a and 121_1b arranged on the first path in the annular cores 12a and 12b are provided at positions that are symmetrical to each other. Do not have to correspond to each other. Similarly, the positions of the magnetic saturation prevention gaps 121_3a and 121_3b do not need to correspond to each other. Further, the current sensor 2a and the current sensor 2b may have different numbers of gaps on the first path or the second path.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, in the above-described first and second embodiments, the configuration in which the magnetic saturation prevention gap is provided in the portion where the leakage magnetic flux enters the annular core has been described. However, it is not always necessary to provide the magnetic saturation prevention gap in the leakage magnetic flux entrance portion. Absent. As described above, if the width of the gap through which the leakage flux passes is the same in the first path from the leakage flux entry portion to the magnetosensitive element and the second path in the opposite direction, the leakage flux is magnetosensitive. It can prevent being detected by the element. Therefore, for example, a magnetic saturation prevention gap is not provided in the portion where the leakage magnetic flux enters, but one or more magnetic saturation prevention gaps are provided on the first path and the second path, respectively, and the magnetic saturation prevention gap in each path is provided. You may comprise so that the total value of the gap width of a gap may become the same.

  Moreover, in the said embodiment, although shown about the structure which provides the gap for magnetic flux measurement in the upper part of an annular core as an example, the gap for magnetic flux measurement may be provided in another position not only in the upper part. Further, for example, a Hall element has been described as an example of the magnetosensitive element. However, the magnetosensitive element may be an element that can detect magnetism, and may be a magnetoresistive element, for example. In addition, the gap provided in the annular core that is not provided with the magnetic sensitive element has been described as the magnetic saturation prevention gap, but may be a gap used for purposes other than magnetic saturation prevention.

1, 2: Current sensors 11, 12: Annular core 13: Hall elements 50, 51, 52: Bus bar 111: Magnetic flux measurement gaps 112, 121: Magnetic saturation prevention gap

Claims (1)

A current sensor having an annular core including a magnetic flux measurement gap and at least one magnetic saturation prevention gap, and a magnetosensitive element provided in the magnetic flux measurement gap for measuring magnetic flux generated by a current path,
A first path that reaches the magnetic measurement gap along the annular core from an entrance portion of leakage magnetic flux from other than the current path, and the magnetic measurement from the entrance portion in a direction opposite to the first path In the second path reaching the gap, the total width of the magnetic saturation prevention gap passing through each path is the same. Current sensor.

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