JP6920832B2 - Current sensor and watt-hour meter - Google Patents

Description

The present invention relates to a current sensor and a watt-hour meter that can reduce a decrease in current measurement accuracy even when an external force is applied to a substrate having a detection coil in 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 magnetic-electric conversion element such as a Hall element is arranged in the gap portion of the magnetic collection core, or a winding in the gap portion of the magnetic collection 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 arranging the element in which the coil pattern is formed on the substrate in the gap portion of the magnetic collecting core has excellent 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 the central opening of the annular magnetic collecting core, and a substrate having a coil pattern is arranged in the 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 collecting core. When the current is a periodic current, the magnetic flux generated according to the period 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 of the current flowing through the current bar.

Japanese Unexamined Patent Publication No. 2010-48755

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. Therefore, when the cross-sectional area of the coil portion changes due to deformation of the detection coil on the substrate, the magnetic flux interlinking changes according to this change, and the detection signal also changes. Further, 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 misalignment of.

Therefore, if the part that fixes the board is deformed due to heat or deterioration over time and external stress is applied, the board will be distorted, the shape and placement position of the detection coil will change, and the current measurement accuracy will decrease. be. Further, since the substrate is plastically deformed by applying an excessive stress during assembly and fixing, the shape and arrangement position of the detection coil are changed accordingly, and there is a problem that the current measurement accuracy is lowered.

The present invention has been made in view of the above, and a current capable of reducing a decrease in current measurement accuracy even when an external force is applied to a substrate having a detection coil in which a coil pattern is formed and the substrate is distorted. It is an object of the present invention to provide a sensor and an electric energy meter.

In order to solve the above-mentioned problems and achieve the object, the current sensor according to the present invention has a gap between a current bar through which a current flows, a magnetic collecting core formed so as to surround the current bar, and the magnetic collecting core. A current sensor provided with a coil pattern for magnetic detection, which is interposed in the current sensor and has a substrate for detecting the amount of current flowing through the current bar. The coil pattern is formed on the substrate, and the coil pattern is formed. It is characterized in that a gap is provided around the detected detection unit.

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

Further, in the current sensor according to the present invention, in the above invention, the gap is formed so as to be along two opposite sides around the detection unit, and the length of the gap along the two sides is the above 2. It is characterized in that it is longer than the length of the coil pattern in the detection unit along the side.

Further, 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.

Further, 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 portion of the substrate.

Further, 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 with a part or all of the other end portion facing the one end portion.

Further, the current sensor according to the present invention is characterized in that, in the above invention, the connection portion is provided in the lateral direction of the substrate.

Further, the watt hour meter according to the present invention calculates the amount of power flowing through the current bar based on the amount of current detected by the current sensor described in any one of the above inventions and the amount of input voltage. It is characterized by that.

According to the present invention, since a gap is provided around the detection unit in which the coil pattern is formed, even when an external force is applied to the substrate and the substrate is distorted, it becomes difficult for the external force to be transmitted to the detection unit, and the detection unit is deformed or deformed. Since misalignment is unlikely to occur, it is possible to reduce a decrease in current measurement accuracy.

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 showing a state of the detection unit interposed in the gap between the ends of the magnetic 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 a modification 1 of the current sensor according to the embodiment of the present invention. FIG. 6 is a plan view of a substrate showing a modification 2 of the current sensor according to the embodiment of the present invention. FIG. 7 is a plan view of a substrate showing a 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 collecting core and a detection unit having a coil pattern is formed in each of the two gaps. FIG. 9 is a plan view showing an example of a substrate in which two gaps are formed in the magnetic collecting core, and a detection unit having a coil pattern in each of the two gaps is inserted and arranged from a direction orthogonal 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 collecting core. FIG. 11 is a block diagram showing a configuration of a watt hour meter using a current sensor.

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. Further, FIG. 2 is a plan view of the substrate 1 shown in FIG. Further, 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 collection core 10. In FIGS. 1 to 3, the current sensor 100 is interposed in a gap G between a current bar 12 through which a current flows, a magnetic collecting core 10 formed so as to surround the current bar 12, and an end portion 11 of the magnetic collecting core 10. A coil pattern 3 for magnetic detection is provided, and a 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 voids V1 and V2 are provided around the detection unit 2 on which the coil pattern is formed.

The coil pattern 3 detects a change in magnetic flux between the gaps G generated according to the magnitude and change of the current flowing through the current bar 12 as an induced voltage. The coil pattern 3 is connected to the current detection circuit 4 formed on the substrate 1 in a region not interposing the gap G. The current detection circuit 4 performs a filter process or the like on the induced voltage input from the coil pattern 3 to extract only the frequency component to be measured, and measures the current flowing through the current bar 12.

The hole 5 provided in the substrate 1 is a screw hole for mounting and fixing the substrate 1 to a fixing portion (not shown). By fixing the substrate 1, the coil pattern 3 of the detection unit 2 in the substrate 1 is fixedly arranged at a predetermined position in the gap G.

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

Here, as shown in FIG. 3, the coil pattern 3 arranged in the gap G has a direction b that deviates from the gap G when the detection unit 2 moves in the direction a that is the end direction of the magnetic collecting core 10. When the area is changed to, or when the area with respect to the end direction in the deformed state is changed, the magnetic flux to be detected changes, and the current measurement accuracy is lowered.

In the present embodiment, the gaps V1 and V2 are provided around the detection unit 2, and only the connection portion 21 to which a part of one side of the detection unit 2 is connected is connected to the substrate 1 side, so that the entire substrate 1 is connected. Deformation is less likely to be transmitted to the detection unit 2. As a result, even when an external force is applied to the entire substrate 1 and the substrate 1 is distorted, the external force is less likely to be transmitted to the detection unit 2, and the coil pattern 3 of the detection unit 2 is less likely to be deformed or misaligned. Can be reduced.

Here, the influence of the deformation of the substrate 1 on the detection unit 2 will be described with reference to FIG. FIG. 4A is a cross-sectional view taken along the line AA of the substrate 1. When an external force is applied to the substrate 1 from the state of FIG. 4 (a), the substrate 1 is greatly deformed as shown in FIG. 4 (b). However, since the detection unit 2 is connected to the substrate 1 side only by a part of the connection units 21, the stress transmission due to deformation is small to the detection unit 2. That is, as shown in FIG. 4C, the substrate 1 main body side draws a characteristic curve LL1 having a large amount of strain, but the detection unit 2 on which the coil pattern 3 is formed draws a characteristic curve LL2 having almost no amount of strain. .. As a result, even if the substrate 1 is greatly deformed, the change in the arrangement position of the detection unit 2 in the gap G is small, and the decrease in the current measurement accuracy using the coil pattern 3 can be suppressed.

As shown in FIG. 2, when the substrate 1 is rectangular and the width A2 in the longitudinal direction is longer than the width A1 in the lateral direction, the substrate 1 is likely to be deformed in the longitudinal direction, so that the gaps V1 and V2 are formed. , At least in the longitudinal direction, and the connecting portion 21 is preferably provided in the lateral direction. Further, it is preferable that one end of the detection unit 2 is a free end as an edge of the substrate 1. With 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 a substrate 1 showing a modification 1 of the current sensor according to the embodiment of the present invention. In this modification 1, the gaps V11 and V12 formed around the detection unit 2a corresponding to the detection unit 2 are formed only on the two opposite sides of the substrate 1 in the lateral direction. Therefore, all of the connection portions 22 of the detection unit 2a on the side facing the edge portion of the substrate 1 are connected to the substrate 1 side. Also with this configuration, it is possible to reduce the transmission of the deformation stress on the substrate 1 main body side to the detection unit 2a.

In addition, in this modification 1, since it is only necessary to form the notches of the voids V11 and V12 linearly, the production becomes easy.

FIG. 6 is a plan view of a substrate 1 showing a modification 2 of the current sensor according to the embodiment of the present invention. In this modification 2, one end of the detection unit 2b corresponding to the detection unit 2 does not become a free end, and a part of the side of the detection unit 2b is connected to the edge of the substrate 1 via a connection unit 23b. Is connected. As with the connecting portion 21, only a part of one side of the connecting portion 23a facing one end of the detecting portion 2b is connected to the substrate 1 side. Also in this modification 2, the gaps V21 and V22 are formed around the detection unit 2b, and the transmission of the deformation stress on the substrate 1 main body side to the detection unit 2b can be reduced.

FIG. 7 is a plan view of a substrate 1 showing a modification 3 of the current sensor according to the embodiment of the present invention. In this modification 3, the detection unit 2c is provided with connecting portions 24c and 24d in the longitudinal direction with respect to the configuration of the detection unit 2b shown in FIG. The detection unit 2c has connection units 24a and 24b corresponding to the connection units 23a and 23b, similarly to the detection unit 2b. Then, the detection unit 2c forms four voids V31 to V34 around the connection portions 24a to 24d. Also in this modification 3, the gaps V31 to V34 are formed around the detection unit 2c, and the transmission of the deformation stress on the substrate 1 main body side to the detection unit 2c can be reduced.

When the deformation of the substrate 1 is large with respect to the lateral direction, it is preferable that the connecting portions are only the connecting portions 24c and 24d. That is, it is preferable to provide a gap in the direction in which the deformation of the substrate 1 is large and connect only a part of the sides in the direction in which the deformation of the substrate 1 is small.

FIG. 8 is a plan view showing an example of a substrate 40 in which two gaps are formed in the magnetic collecting core 10 and detection units 42a and 42b having coil patterns are formed in the two gaps, respectively. As shown in FIG. 8, the substrate 40 forms two detection units 42a and 42b corresponding to the detection unit 2 at the edge portion, and forms voids V41, V42, V43 and V44 corresponding to the voids 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, respectively.

FIG. 9 shows an example of a substrate 50 in which two gaps are formed in the magnetic collecting core 10 and detection units 52a and 52b having coil patterns are inserted and arranged in the two gaps from directions orthogonal to the current bar 12. It is a figure. As shown in FIG. 9, the substrate 50 forms detection units 52a and 52b corresponding to the two gap positions. The detection unit 52a is provided at the central portion of the substrate 50, and the detection unit 52b is provided at the edge portion of the substrate 50. The detection unit 52 has a connection unit in which a part of each side is connected to the substrate 50 side, and four voids V51 to V54 are formed. Further, in the detection unit 52b, similarly to the detection unit 2, only a part of one side facing the edge portion of the substrate 50 is connected to the substrate 50 side, and voids V56 and V57 are formed. This current sensor also has voids V51 to V54, V56, and V57 formed around the detection units 52a and 52b, respectively, so as to reduce the transmission of deformation stress on the substrate 50 main body side to the detection units 52a and 52b, respectively.

FIG. 10 is a perspective view showing the overall configuration of the current sensor 101 showing a state in which the substrate 50 shown in FIG. 9 is arranged in the two gaps G1 and G2 of the magnetic collecting core 10. As shown in FIG. 10, the current sensor 101 includes magnetic collecting cores 10a and 10b in which the magnetic collecting core 10 is divided by two caps G1 and G2. The substrate 50 having the two detection units 52a and 52b is arranged so 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-mentioned current sensor 100 (100, 101). As shown in FIG. 11, the electric energy meter 200 includes the above-mentioned current sensor 100, voltage sensor 201, current measurement results output from the substrate 1 (1,40,50) of the current sensor 100, and voltage sensor 201. It has a power amount calculation unit 202 that calculates the power amount of the current bar 12 based on the voltage measurement result output from, and an output unit 203 that outputs the power amount calculation result. As a result, the electric energy can be measured using the above-mentioned current sensors 100 and 101.

1,40,50 Substrates 2,2a, 2b, 2c, 42a, 42b, 52a, 52b Detection unit 3 Coil pattern 4 Current detection circuit 5 Holes 10, 10, 10b Magnetic collecting core 11 End 12 Current bars 21, 22, 23a, 23b, 24c, 24d, 24a, 24b, 24c, 24d Connection unit 100, 101 Current sensor 200 Electric energy meter 201 Voltage sensor 202 Electric energy calculation unit 203 Output unit G Gap V1, V2, V11, V12, V31 to V34 , V41-V44, V51-V57 voids

Claims (5)

A current bar through which a current flows, a magnetic collecting core formed so as to surround the current bar, and a coil pattern for magnetic detection are provided via a gap between the magnetic collecting cores, and the amount of current flowing through the current bar is measured. A current sensor with a board to detect
The detection portion of the rectangular region on which the coil pattern is formed is provided on the substrate and arranged in the gap, and one end of the detection portion is an edge portion on the lateral side of the substrate, and at least the substrate. A current sensor characterized in that gaps cut from the edge portion of the substrate are formed at both ends of the detection portion corresponding to the longitudinal direction side of the substrate. The length of the gap of said end portion, a current sensor according to claim 1, characterized in that longer than the length of the coil pattern. The current sensor according to claim 1 or 2 , wherein the detection unit is connected to the substrate side in part or in whole of the other end portion facing the one end portion. The detection unit is connected to the substrate side with a part of the other end portion facing the one end portion.
The current sensor according to claim 1 or 2, wherein the gap is continuously formed along the other end of the detection unit. A watt hour meter characterized by calculating the amount of power flowing through the current bar based on the amount of current detected by the current sensor according to any one of claims 1 to 4 and the amount of input voltage.

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