JP2018146388A - Current sensor and electricity meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor and an electricity meter which can measure an electric current almost as accurately as when an external force is applied to a substrate with a detection coil where a coil pattern is formed.SOLUTION: The current sensor includes: a current bar for flowing a current; a magnetism collecting core surrounding the current bar; a substrate 1 for detecting the amount of the current flowing in the current bar, the substrate having a coil pattern 3 for conducting a magnetic detection by being inserted into a gap of the magnetism collecting core, the coil pattern 3 being formed on the substrate 1; and voids V1 and V2 around a detection unit 2 in which the coil pattern 3 is formed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a current sensor and a watt hour meter capable of reducing a decrease in current measurement accuracy even when an external force is applied to a substrate having a detection coil on which a coil pattern is formed and the substrate is distorted.

  Conventionally used current sensors include a current transformer (current transformer: CT), a configuration in which a magnetoelectric conversion element such as a Hall element is disposed in the gap portion of the magnetic collecting core, or a coil wound in the gap portion of the magnetic collecting core. There is a configuration having an element in which a coil pattern is formed on a wire coil or a dielectric substrate. In particular, the method of disposing an element having a coil pattern formed on a substrate in the gap portion of the magnetic flux collecting core has the characteristics that it is excellent in linearity and temperature characteristics, has a small number of parts, and is easy to manufacture (see Patent Document 1). .

  In the current sensor described in Patent Document 1, a current bar is passed through a central opening of an annular magnetic collecting core, and a substrate on which a coil pattern is applied is arranged in a gap portion of the magnetic collecting core. When a current flows through the current bar, a magnetic flux proportional to the magnitude of the current flowing through the current bar is generated around the current path. The generated magnetic flux is collected by the magnetic flux collecting core. When the current is a periodic current, the magnetic flux generated according to the cycle also changes periodically. As a result, an induced voltage corresponding to the magnitude and frequency of the current is generated in the detection coil having the coil pattern, and this induced voltage is used as a detection signal for the current flowing through the current bar.

JP 2010-48755 A

  By the way, the current sensor described in Patent Document 1 outputs a detection signal proportional to the magnitude of the total magnetic flux interlinking the entire detection coil. For this reason, when the cross-sectional area of the coil portion changes due to deformation of the detection coil of the substrate, the interlinkage magnetic flux changes according to this change, and the detection signal also changes. Also, the magnetic flux generated in the gap of the magnetic collecting core becomes stronger as it approaches the end of the magnetic collecting core from the center of the gap, and becomes weaker as it moves away from the end of the magnetic collecting core. The detection signal also changes due to the positional deviation.

  Therefore, when the part that fixes the substrate is deformed due to heat or aging, and external stress is applied, the substrate is distorted, the shape and position of the detection coil change, and the current measurement accuracy decreases. is there. In addition, the substrate is plastically deformed even when an excessive stress is applied at the time of assembly and fixing, and accordingly, there is a problem that the shape and the arrangement position of the detection coil are changed and the current measurement accuracy is lowered.

  The present invention has been made in view of the above, and it is possible to reduce a decrease in current measurement accuracy even when an external force is applied to a substrate having a detection coil on which a coil pattern is formed. It aims at providing a sensor and a watt-hour meter.

  In order to solve the above-described problems and achieve the object, a current sensor according to the present invention includes a current bar for passing a current, a magnetic core formed so as to surround the current bar, and a gap between the magnetic cores. A current sensor provided with a coil pattern for detecting magnetism, and a substrate for detecting the amount of current flowing through the current bar, wherein the coil pattern is formed on the substrate and the coil pattern is formed A gap is provided around the detected portion.

  The current sensor according to the present invention is characterized in that, in the above invention, the gap is provided at two or more locations around the detection unit.

  In the current sensor according to the present invention, in the above invention, the gap is formed so as to extend along two sides facing each other around the detection unit, and the length of the gap along the two sides is 2 It is longer than the length of the coil pattern in the said detection part along a side, It is characterized by the above-mentioned.

  Moreover, the current sensor according to the present invention is characterized in that, in the above invention, the detection unit has a connection unit connected to the substrate side at a portion other than the gap.

  The current sensor according to the present invention is characterized in that, in the above invention, one end of the detection unit is an edge of the substrate.

  Moreover, the current sensor according to the present invention is characterized in that, in the above invention, the detection unit is connected to the substrate side at a part or all of the other end portion opposed to the one end portion.

  In the current sensor according to the present invention as set forth in the invention described above, the connecting portion is provided in a short direction of the substrate.

  Moreover, the watt-hour meter concerning this invention calculates the electric energy which flows through the said current bar based on the electric current amount which the current sensor as described in any one of said invention detected, and the input voltage amount. It is characterized by that.

  According to the present invention, since the gap is provided around the detection unit on which the coil pattern is formed, even when the external force is applied to the substrate and distorted, the external force is not easily transmitted to the detection unit, Since it is difficult for the position shift to occur, a decrease in current measurement accuracy can be reduced.

FIG. 1 is a perspective view showing a schematic configuration of a current sensor according to an embodiment of the present invention. FIG. 2 is a plan view of the substrate shown in FIG. FIG. 3 is a cross-sectional view illustrating a state of the detection unit interposed in the gap between the end portions of the magnetic flux collecting core. FIG. 4 is an explanatory diagram for explaining the influence on the detection unit due to the deformation of the substrate. FIG. 5 is a plan view of a substrate showing Modification 1 of the current sensor according to the embodiment of the present invention. FIG. 6 is a plan view of a substrate showing Modification 2 of the current sensor according to the embodiment of the present invention. FIG. 7 is a plan view of a substrate showing Modification 3 of the current sensor according to the embodiment of the present invention. FIG. 8 is a plan view showing an example of a substrate in which two gaps are formed in the magnetic flux collecting core and detection portions each having a coil pattern are formed in the two gaps. FIG. 9 is a plan view showing an example of a substrate in which two gaps are formed in the magnetic flux collecting core, and detectors each having a coil pattern are inserted and arranged in a direction perpendicular to the current bar. FIG. 10 is a perspective view showing a schematic configuration of a current sensor showing a state in which the substrate shown in FIG. 9 is arranged in two gaps of the magnetic flux collecting core. FIG. 11 is a block diagram showing a configuration of a watt-hour meter using a current sensor.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a schematic configuration of a current sensor 100 according to an embodiment of the present invention. FIG. 2 is a plan view of the substrate 1 shown in FIG. FIG. 3 is a cross-sectional view showing a state of the detection unit 2 interposed in the gap G between the end portions 11 of the magnetic flux collecting core 10. 1 to 3, a current sensor 100 is interposed in a gap G between a current bar 12 through which a current flows, a magnetic core 10 formed so as to surround the current bar 12, and an end 11 of the magnetic core 10. The coil pattern 3 for performing magnetic detection is provided, and the substrate 1 for detecting the amount of current flowing through the current bar 12 is provided. The coil pattern 3 is formed on a dielectric substrate 1, and two gaps V1 and V2 are provided around the detection unit 2 on which the coil pattern is formed.

  The coil pattern 3 detects, as an induced voltage, a magnetic flux change between the gaps G generated according to the magnitude and change of the current flowing through the current bar 12. The coil pattern 3 is connected to a current detection circuit 4 formed in a region on the substrate 1 where no gap G is interposed. The current detection circuit 4 performs a filter process or the like on the induced voltage input from the coil pattern 3, performs a process of extracting only a frequency component for measurement, and measures a current flowing through the current bar 12.

  In addition, the hole 5 provided in the board | substrate 1 is a screw hole for attaching and fixing the board | substrate 1 to the fixing | fixed part which is not shown in figure. By fixing the substrate 1, the coil pattern 3 of the detection unit 2 in the substrate 1 is fixedly disposed at a predetermined position in the gap G.

  The detection unit 2 is connected via a connection unit 21 to the substrate 1 side on which the current detection circuit 4 is provided. Further, a part of the gaps V1 and V2 is formed along two opposing sides around the detection unit 2, and the length L1 of the gap along these two sides is within the detection unit 2 along the two sides. The coil pattern 3 is longer than the length L2. In FIG. 2, a part of the side where the connection part 21 is formed is connected to the substrate 1 side, and the gaps V1 and V2 wrap around the connection part 21 side.

  Here, as shown in FIG. 3, the coil pattern 3 arranged in the gap G has a direction b deviating from the gap G when the detection unit 2 moves in the direction a, which is the end direction of the magnetic flux collecting core 10. Further, when the area with respect to the end direction in the case of deformation is changed, the detected magnetic flux changes, and the current measurement accuracy decreases.

  In the present embodiment, since the gaps V1 and V2 are provided around the detection unit 2 and only the connection unit 21 to which a part of one side of the detection unit 2 is connected is connected to the substrate 1 side, Is difficult to be transmitted to the detection unit 2. As a result, even when the external force is applied to the entire substrate 1 and distorted, the external force is not easily transmitted to the detection unit 2, and the coil pattern 3 of the detection unit 2 is not easily deformed or misaligned. Can be reduced.

  Here, with reference to FIG. 4, the influence on the detection part 2 by the deformation | transformation of the board | substrate 1 is demonstrated. FIG. 4A is a cross-sectional view of the substrate 1 along the line AA. When an external force is applied to the substrate 1 from the state of FIG. 4A, the substrate 1 is greatly deformed as shown in FIG. 4B. However, since the detection unit 2 is connected to the substrate 1 only by a part of the connection units 21, the detection unit 2 transmits less stress due to deformation. That is, as shown in FIG. 4C, the substrate 1 main body side draws a characteristic curve LL1 with a large amount of distortion, but the detection unit 2 on which the coil pattern 3 is formed draws a characteristic curve LL2 with little amount of distortion. . As a result, even if the substrate 1 is greatly deformed, a change in the arrangement position of the detection unit 2 in the gap G is small, and a decrease in current measurement accuracy using the coil pattern 3 can be suppressed.

  As shown in FIG. 2, when the substrate 1 is rectangular and the longitudinal width A2 is longer than the lateral width A1, the substrate 1 is likely to be deformed in the longitudinal direction. It is preferable to provide at least the longitudinal direction and the connecting portion 21 in the short direction. Further, it is preferable that one end of the detection unit 2 is a free end as an edge of the substrate 1. By adopting these configurations, it is possible to reduce the transmission of deformation stress on the substrate 1 main body side.

  FIG. 5 is a plan view of the substrate 1 showing Modification 1 of the current sensor according to the embodiment of the present invention. In the first modification, the gaps V11 and V12 formed around the detection unit 2a corresponding to the detection unit 2 are formed on only two opposite sides of the substrate 1 in the short direction. Therefore, the connection part 22 of the detection part 2a is connected to the substrate 1 side in its entirety on the side facing the edge of the substrate 1. Also with this configuration, it is possible to reduce the transmission of deformation stress on the substrate 1 main body side to the detection unit 2a.

  In the first modification, it is only necessary to form the notches in the gaps V11 and V12 in a straight line, so that the manufacturing becomes easy.

  FIG. 6 is a plan view of the substrate 1 showing Modification Example 2 of the current sensor according to the embodiment of the present invention. In the second modification, one end of the detection unit 2b corresponding to the detection unit 2 does not become a free end, but via a connection unit 23b in which a part of the side of the detection unit 2b is connected to the edge of the substrate 1. Connected. In addition, as for the connection part 23a which opposes the one end part of the detection part 2b, only a part of 1 side is connected to the board | substrate 1 side similarly to the connection part 21. FIG. Also in this modified example 2, gaps V21 and V22 are formed around the detection unit 2b, and the transmission of deformation stress on the substrate 1 body side to the detection unit 2b can be reduced.

  FIG. 7 is a plan view of the substrate 1 showing Modification 3 of the current sensor according to the embodiment of the present invention. In the third modification, the detection unit 2c is further provided with connecting portions 24c and 24d in the longitudinal direction with respect to the configuration of the detection unit 2b shown in FIG. Similarly to the detection unit 2b, the detection unit 2c includes connection units 24a and 24b corresponding to the connection units 23a and 23b. And the detection part 2c forms the four space | gap V31-V34 around these connection parts 24a-24d. Also in the third modification, the gaps V31 to V34 are formed around the detection unit 2c, and the transmission of deformation stress on the substrate 1 main body side to the detection unit 2c can be reduced.

  In addition, when the deformation | transformation of the board | substrate 1 is large with respect to a transversal direction, it is preferable that a connection part is only connection part 24c, 24d. That is, it is preferable to provide a gap in a direction in which the deformation of the substrate 1 is large and connect only a part of the side in a direction in which the deformation of the substrate 1 is small.

  FIG. 8 is a plan view showing an example of the substrate 40 in which two gaps are formed in the magnetic flux collecting core 10 and detection portions 42a and 42b each having a coil pattern are formed in the two gaps. As shown in FIG. 8, the substrate 40 is formed with two detection portions 42a and 42b corresponding to the detection portion 2 at the edge, and voids V41, V42, V43 and V44 corresponding to the spaces V1 and V2, respectively. doing. This current sensor also forms gaps V41, V42, V43, and V44 around the detection units 42a and 42b, respectively, so as to reduce the transmission of deformation stress on the substrate 40 main body side to the detection units 42a and 42b.

  FIG. 9 is a plan view showing an example of a substrate 50 in which two gaps are formed in the magnetic flux collecting core 10 and detectors 52a and 52b each having a coil pattern are inserted and arranged in a direction perpendicular to the current bar 12 in the two gaps. FIG. As shown in FIG. 9, the substrate 50 forms detection portions 52a and 52b corresponding to two gap positions. The detection unit 52 a is provided at the central portion of the substrate 50, and the detection unit 52 b is provided at the edge of the substrate 50. The detection part 52 has a connection part in which a part of each side is connected to the substrate 50 side, and four gaps V51 to V54 are formed. Similarly to the detection unit 2, the detection unit 52 b is connected to the substrate 50 side only at a part of one side facing the edge of the substrate 50, and gaps V <b> 56 and V <b> 57 are formed. Also in this current sensor, gaps V51 to V54, V56, and V57 are formed around the detection units 52a and 52b, respectively, to reduce the transmission of deformation stress on the substrate 50 main body side to the detection units 52a and 52b.

  FIG. 10 is a perspective view showing an overall configuration of the current sensor 101 showing a state in which the substrate 50 shown in FIG. 9 is disposed in the two gaps G1 and G2 of the magnetic flux collecting core 10. FIG. As shown in FIG. 10, the current sensor 101 includes a magnetic flux collecting core 10a and 10b in which the magnetic flux collecting core 10 is divided by two caps G1 and G2. The substrate 50 having the two detection units 52a and 52b is arranged such that the detection units 52a and 52b are interposed in the two gaps G1 and G2, respectively.

  FIG. 11 is a block diagram showing a configuration of a watt-hour meter 200 using the above-described current sensor 100 (100, 101). As shown in FIG. 11, the watt-hour meter 200 includes the current sensor 100, the voltage sensor 201, the current measurement result output from the substrate 1 (1, 40, 50) of the current sensor 100, and the voltage sensor 201. The power amount calculation unit 202 that calculates the power amount of the current bar 12 based on the voltage measurement result output from the output unit 203 and the output unit 203 that outputs the power amount calculation result. Thereby, electric energy measurement can be performed using the current sensors 100 and 101 described above.

DESCRIPTION OF SYMBOLS 1,40,50 Board | substrate 2,2a, 2b, 2c, 42a, 42b, 52a, 52b Detection part 3 Coil pattern 4 Current detection circuit 5 Hole 10, 10, 10b Magnetic collecting core 11 End part 12 Current bar 21,22 23a, 23b, 24c, 24d, 24a, 24b, 24c, 24d Connection unit 100, 101 Current sensor 200 Watt meter 201 Voltage sensor 202 Power amount calculation unit 203 Output unit G Gap V1, V2, V11, V12, V31 to V34 , V41 to V44, V51 to V57

Claims (8)

A current bar for passing current, a magnetic flux collecting core formed so as to surround the current bar, and a coil pattern for magnetic detection interposed between gaps of the magnetic flux collecting core are provided, and the amount of current flowing through the current bar is determined. A current sensor having a substrate to be detected,
The current sensor, wherein the coil pattern is formed on a substrate, and a gap is provided around a detection portion where the coil pattern is formed.   The current sensor according to claim 1, wherein the gap is provided at two or more locations around the detection unit. The gap is formed along two opposing sides around the detection unit,
The current sensor according to claim 2, wherein a length of the gap along the two sides is longer than a length of a coil pattern in the detection unit along the two sides.   The current sensor according to claim 1, wherein the detection unit includes a connection unit connected to the substrate side at a portion other than the gap.   The current sensor according to claim 1, wherein one end of the detection unit is an edge of the substrate.   The current sensor according to claim 5, wherein the detection unit is connected to the substrate side at a part or all of the other end portion facing the one end portion.   The current sensor according to claim 4, wherein the connection portion is provided in a short direction of the substrate.   A watt hour meter that calculates the amount of power flowing through the current bar based on the amount of current detected by the current sensor according to claim 1 and an input voltage amount.

Images