JP2023049304A - Electric current sensor, and watthour meter - Google Patents

Abstract

To provide an electric current sensor and watthour meter that can further reduce fluctuations of electric current detection sensitivity accompanied by a position displacement of a substrate having a magnetic detection unit such as a pattern coil and the like provided.SOLUTION: An electric current sensor, which has: an electric current bar 10 through which an electric current to be detected flows; at least two or more magnetism collection cores 2a and 2b collecting a magnetic flux generating by the electric current flowing to the electric current bar 10; and a substrate 3 that has at least two or more pattern coils 3a and 3b, detects the electric current flowing to the electric bar 10 on the basis of a magnetic detection result the pattern coils 3a and 3b detect. Two joint electric bars 11 and 12 to be coupled to each of both ends of the electric current bar 10 are arranged parallel with a longitudinal direction of the magnetism collection cores 2a and 2b at least from coupling points P2 and P1 between the electric current bar 10 and the electric current bars 11 and 12 to an end part in the longitudinal direction of the magnetism collection cores 2a and 2b.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current sensor and a watt-hour meter capable of further reducing variation in current detection sensitivity due to positional deviation of a substrate on which a magnetic detection section such as a pattern coil is arranged.

Conventionally used current sensors include a current transformer (CT), a configuration in which a magnetoelectric conversion element such as a Hall element is arranged in the gap of the magnetic core, There is a configuration with a wound coil or an element in which a coil pattern is formed on a dielectric substrate. Furthermore, there is also a configuration in which a current is detected by directly arranging a Hall element or the like without using a magnetic collecting core. Since these current sensors are electrically separated from the circuit where the primary current flows, they are excellent in that they can accurately measure current without affecting the circuit on the primary current side. . Furthermore, the method of arranging the elements having the coil pattern has excellent linearity and temperature characteristics, and has the characteristics of facilitating manufacturing with a small number of parts (see Patent Document 1).

In the current sensor disclosed in Patent Document 1, a current bar is passed through a central opening of an annular magnetism collecting core, and a substrate provided with a pattern coil is arranged in the gap portion of the magnetism 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. If the current is a periodic current, the generated magnetic flux also changes periodically according to the period. 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.

JP 2010-48755 A

By the way, a current sensor in which two magnetic collecting cores are arranged in parallel and a substrate with a coil pattern formed in the center of the gap is arranged, for example, as shown in FIG. Magnetic flux collecting cores 2a and 2b are arranged in parallel on the upper and lower sides, and a substrate 3 on which pattern coils 3a and 3b are formed is arranged in the center to detect the current flowing through the current bar 10. FIG. In this current sensor, the pattern coils 3a and 3b are arranged in the center of the gap between the magnetic cores 2a and 2b, thereby reducing the measurement error caused by the external magnetic field in the horizontal direction (X direction). Here, the current bar 10 and the pattern coils 3a and 3b can be arranged in the center of the gap between the magnetic cores 2a and 2b to reduce the measurement error. When the coils 3a and 3b are placed in the center of the gap between the magnetic cores 2a and 2b, the current bar 10 is displaced from the center of the gap and different magnetic fluxes are collected in the magnetic cores 2a and 2b, resulting in large measurement errors. Become.

Therefore, for example, as shown in FIG. 7, a current sensor is conceivable in which a through hole 20 is formed in a current bar 10 and a substrate 3 having pattern coils 3a and 3b formed therethrough is passed therethrough. In this current sensor, the pattern coils 3a, 3b and the current bar 10 can be arranged in the center of the gap between the magnetic collecting cores 2a, 2b.

However, in any current sensor, if the substrate 3 is displaced in the vertical direction from the center of the gap, the magnetic flux density distribution in the gap becomes asymmetrical in the vertical direction due to the displacement amount, and the current detection sensitivity decreases. fluctuate greatly.

Moreover, when mounting the current sensor, it is necessary to extend the current bar 10 to the terminals on the main body side. For example, as shown in FIG. 7, coupling current bars 11' and 12' extending in a direction (-Z direction) perpendicular to the longitudinal direction (Y direction) of the magnetic cores 2a and 2b and coupled to the current bar 10 must be formed. In this case, the coupling current bars 11' and 12' surround the lower magnetism collecting core 2b, resulting in a difference in magnetic flux density collected by the upper and lower magnetism collecting cores 2a and 2b. This also applies to the current sensor shown in FIG. Fluctuations in the current detection sensitivity due to the arrangement of the coupling current bars 11' and 12' are due to variations in the current detection sensitivity due to the vertical asymmetry of the magnetic flux density distribution caused by the displacement of the current bar 10 and the substrate 3 from the center of the gap. Accordingly, there is a problem that the variation of the overall current detection sensitivity becomes large.

The present invention has been made in view of the above, and is a current sensor and a watt-hour meter capable of further reducing fluctuations in current detection sensitivity due to positional deviation of a substrate on which a magnetic detection unit such as a pattern coil is arranged. intended to provide

In order to solve the above-described problems and achieve the object, the current sensor according to the present invention comprises a current bar through which a current to be detected flows, and at least two magnet collectors that collect magnetic flux generated by the current flowing in the current bar. A current sensor that has a core and a substrate having at least two magnetic detection units, and detects the current flowing through the current bar based on the magnetic detection results detected by the magnetic detection units, Two coupled current bars respectively coupled to both ends of a current bar extend at least along the length of the magnetic core from a coupling point between the current bar and the coupled current bar to a longitudinal end of the magnetic core. It is characterized in that it is arranged parallel to the magnetism collecting core toward the direction.

Further, in the above invention, the current sensor according to the present invention includes a current bar through which a current to be detected flows, at least two or more magnetic flux collecting cores that collect magnetic flux generated by the current flowing in the current bar, and at least two or more and a substrate having a magnetic detection unit, and detects the current flowing through the current bar based on the magnetic detection result detected by the magnetic detection unit, wherein the current bar is the magnetic collecting A through hole is formed through a gap formed between the cores and perpendicular to the longitudinal direction of the magnetic flux collecting core, and the substrate passes through the through hole in the gap. , two coupled current bars disposed on both sides of the through hole through the through hole and respectively coupled to both ends of the current bar, the magnetic flux gathering from at least the coupling point between the current bar and the coupled current bar It is characterized in that it is arranged parallel to the magnetic flux collecting core in the longitudinal direction of the magnetic flux collecting core until the end of the core in the longitudinal direction.

Further, the current sensor according to the present invention is characterized in that, in the above invention, the magnetic collecting core, the current bar and the substrate are fixed by a positioning mechanism formed in a housing.

In the current sensor according to the present invention, the two or more magnetic detection units are pattern coils formed on the substrate.

In the current sensor according to the present invention, the two or more magnetic detection units are pattern coils formed on the same plane on the substrate.

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

According to the present invention, it is possible to further reduce fluctuations in current detection sensitivity due to the positional displacement of the substrate on which the magnetic detection unit such as the pattern coil is arranged.

FIG. 1 is a perspective view showing the configuration of a current sensor that is an embodiment of the present invention. FIG. 2 is a cross-sectional view of the current sensor shown in FIG. 1, taken along the line AA. FIG. 3 is a plan view of the substrate. FIG. 4 is a plan view of the current sensor fixed to the housing. 5 is a cross-sectional view of the current sensor shown in FIG. 4 taken along the line BB. FIG. 6 is a perspective view showing the configuration of a current sensor of conventional example B in which a substrate and current bars are arranged to intersect. FIG. 7 is a perspective view showing the configuration of a current sensor of conventional example A in which a substrate is arranged through a through-hole of a current bar. FIG. 8 is a diagram showing the magnetic field distribution with respect to the vertical positional deviation of the substrate in Conventional Example B. In FIG. FIG. 9 is a diagram showing the magnetic field distribution with respect to the vertical positional deviation of the substrate in the conventional example A without the coupling current bar. FIG. 10 is a diagram showing the magnetic field distribution with respect to the vertical positional deviation of the substrate in Conventional Example A in which the coupling current bar is coupled in the -Y direction. FIG. 11 is a diagram showing the magnetic field distribution with respect to the vertical positional displacement of the substrate in this embodiment. 12A and 12B are graphs comparing the variation rate of the current detection sensitivity with respect to the vertical positional deviation of the substrate in the current sensors of the present embodiment and the conventional examples A and B. FIG. FIG. 13 is a block diagram showing an example of a watt-hour meter using the current sensor shown in FIG. FIG. 14 is a vector diagram between three-phase currents and three-phase voltages.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view showing the configuration of a current sensor that is an embodiment of the present invention. 2 is a cross-sectional view of the current sensor shown in FIG. 1, taken along the line AA. As shown in FIGS. 1 and 2, the current sensor has a current bar 10, magnetic collecting cores 2a and 2b and a substrate 3. FIG. The magnetic flux collection cores 2 a and 2 b are arranged parallel to the Z direction along the Y direction, and collect magnetic flux generated by the current flowing through the current bar 10 . The current bar 10 is arranged orthogonally to the Y direction through the center C of the gap G formed between the magnetism collecting cores 2a and 2b. A through hole 20 through which the substrate 3 penetrates is formed in the gap G in the current bar 10 .

The substrate 3 has pattern coils 3a and 3b as two magnetic detectors. The substrate 3 is inserted into the through holes 20 of the current bar 10 . A central portion of the substrate 3 in the Y direction is arranged at the position of the through hole 20 . The two pattern coils 3a and 3b are arranged on both sides of the through-hole 20, and the distance d between the XY plane passing through the center C of the through-hole 20 and the inner surfaces 2c and 2d of the magnetic collecting cores 2a and 2b is equal to are arranged so that Each of the pattern coils 3a and 3b detects the magnetic flux density of the magnetic flux collected by the magnetic collecting cores 2a and 2b.

Coupling current bars 11 and 12 are coupled to coupling points P2 and P1 at both ends of the current bar 10, respectively. The coupling current bars 11 and 12 are arranged at least from the coupling points P2 and P1 to the ends L in the longitudinal direction (Y direction) of the magnetism collecting cores 2a and 2b with respect to the longitudinal direction of the magnetism collecting cores 2a and 2b. are arranged parallel to each other. 1 and 2, the coupling current bars 11, 12 are arranged in parallel extending from coupling points P2, P1 in the -Y direction. Therefore, the coupling current bars 11 and 12 are arranged so as to surround the air gap G and not surround the magnetism collecting cores 2a and 2b. The connecting points P2 and P1 are bending points between the linear current bar 10 and the connecting current bars 11 and 12. As shown in FIG. In addition, the coupling current bars 11 and 12 are further bent in the -X direction outside the ends L in the -Y direction. That is, the current bar 10 and the combined current bar are one current bar 1 .

FIG. 3 is a plan view of the substrate 3. FIG. As shown in FIG. 3, the pattern coils 3a and 3b detect the magnetic field generated by the current I flowing through the current bar 10, and generate an induced voltage corresponding to the current and frequency. As described above, the pattern coils 3a and 3b are evenly arranged on the left and right sides of the current bar 10, and the pattern coils 3a and 3b detect magnetic fluxes Φ generated by the current I and having different directions. The pattern coils 3a and 3b are four-layer pattern coils, respectively, and are coupled via vias a1, b1, c1 and d1 and vias a2, b2, c2 and d2, respectively. The external connection terminals 22a and 22b are terminals for connecting to a signal processing circuit (not shown). The pattern coils 3a and 3b are connected in series so that the induced voltages generated in the respective coils are added. Then, the induced voltage is integrated by a signal processing circuit outside or inside the substrate, and a detection signal proportional to the current I is output. Each of the pattern coils 3a and 3b may be of one layer or an even number of layers of two or more layers. Moreover, in FIG. 3, the pattern coils 3a and 3b have a square shape, but they may have a circular shape or the like. Each layer is formed on the same plane parallel to the surface of the substrate 3 .

With such a configuration, the substrate 3 having the pattern coils 3a and 3b is arranged in the center of the gap G formed by the magnetic collecting cores 2a and 2b, and the current bar 10 is arranged through the center C of the gap G. be done.

FIG. 4 is a plan view of the current sensor fixed to the housing 100. FIG. 5 is a cross-sectional view of the current sensor shown in FIG. 4 taken along the line BB. As shown in FIGS. 4 and 5, in the current sensor, the current bar 10, magnetic flux collecting cores 2a and 2b, and substrate 3 are positioned by a positioning mechanism 30 formed in the housing 100. FIG. The positioning mechanism 30 is an insulating member with low magnetic permeability.

The positioning mechanism 30 is formed in the housing 100 of the device on which the current sensor is mounted. The positioning mechanism 30 is formed with concave portions 31, 32, 33, 34, and 35 that are open in the Y direction, and the base portion in the -Y direction is coupled to the housing 100 side. The recesses 31 and 32 are holes into which the magnetism collecting cores 2a and 2b are respectively fitted from the direction AR (-Y direction), and the magnetism collecting cores 2a and 2b are locked by claws 31a and 32a. The recesses 33 and 34 are holes into which the current bar 10 is fitted from the direction AR, and the current bar 10 is locked by the claws 33a and 34a. The concave portion 35 is a hole into which the substrate 3 is fitted from the direction AR, and the substrate 3 is locked by a claw (not shown). The claws (not shown) are claws formed in the recess 35, and engage with claw receivers formed on the substrate 3 to lock the substrate 3. As shown in FIG.

Here, the fluctuation rate of the current detection sensitivity of the current sensor due to the vertical positional deviation of the substrate 3 will be described. FIG. 6 is a perspective view showing the configuration of the current sensor of conventional example B in which the substrate 3 and the current bar 10 are arranged to cross each other. FIG. 7 is a perspective view showing the configuration of a conventional current sensor in which the substrate 3 is arranged through the through hole 20 of the current bar 10. As shown in FIG.

As shown in FIG. 8, in the current sensor of Conventional Example B, the distance between the current bar 10 and the pattern coils 3a and 3b changes when the substrate 3 shifts in the vertical direction (Z direction). The strength H of the magnetic field generated by the current flowing through the current bar 10 is H=I/(2πr) where the current I of the current bar 10 and the radius r from the current bar 10 are satisfied. , 3b is shifted, the radius r is changed, and the current detection sensitivity in the vicinity of the current bar 10 is largely changed.

On the other hand, as shown in FIG. 9, in the current sensor of the conventional example A, since the through hole 20 is provided in the center of the current bar 10, the magnetic field near the current bar 10 is canceled vertically. Even if the position is shifted in the direction, it is possible to suppress the fluctuation of the current detection sensitivity.

However, as shown in FIG. 10, in the current bar 1' of the conventional example A, the coupled current bars 11' and 12' coupled with the current bar 10 extend in the -Z direction and are orthogonal to each other around the magnet collecting core 2b. ing. Therefore, the magnetic flux density of the magnetic flux collecting core 2b is higher than that of the magnetic flux collecting core 2a. In this case, as shown in FIG. 10, due to the nonlinearity of the magnetic characteristics, the flow of magnetic flux between the magnetic flux collecting cores 2a and 2b becomes vertically asymmetrical. In FIG. 10, the magnetic flux on the magnetic core 2b side is dense. If the positions of the pattern coils 3a and 3b shift up and down in this state, the current detection sensitivity will fluctuate greatly.

In contrast, in the present embodiment, as shown in FIG. 11, the coupling current bars 11 and 12 are arranged parallel to the longitudinal direction (Y direction) of the magnetic flux collection cores 2a and 2b so that the coupling current bars 11 and 12 are concentrated. The magnetic cores 2a and 2b are not enclosed. As a result, the difference in magnetic flux density between the upper and lower magnetic flux collecting cores 2a and 2b can be reduced, and the flow of magnetic flux density can be made vertically symmetrical. Therefore, in the present embodiment, even if pattern coils 3a and 3b (substrate 3) are displaced vertically, it is possible to suppress fluctuations in current detection sensitivity.

FIG. 12 is a diagram comparing the current detection sensitivity variation rate with respect to the vertical positional deviation of the substrate 3 in the current sensors of the present embodiment and the conventional examples A and B. In FIG. As shown in FIG. 12, in conventional example A, the fluctuation rate of current detection sensitivity is greatly reduced compared to conventional example B. In the present embodiment, the fluctuation rate of current detection sensitivity can be further reduced. can.

A current sensor may be provided with two or more pairs of magnetism collecting cores 2a and 2b and pattern coils 3a and 3b provided for each magnetism collecting core 2a and 2b. That is, a plurality of magnetic collecting cores 2a, 2b and pattern coils 3a, 3b shown in FIG. 1 may be provided along one current bar 10, and detected values at each pattern coil 3a, 3b may be integrated. In this case, the plurality of pattern coils 3a and 3b may be provided on the same substrate.

<Watt meter>
FIG. 13 is a block diagram showing an example of watt-hour meter 200 using the current sensor shown in this embodiment. This watthour meter 200 measures the three-phase electric energy between the power source SP and the load LD, and is obtained by the two-wattmeter method. Note that FIG. 14 shows a vector diagram between three-phase currents IR, IS, IT and three-phase voltages VR, VS, VT.

As shown in FIG. 13, the watt hour meter 200 has current sensors 103a and 103b, voltage sensors 201a and 201b, a power amount calculator 202, and an output unit 203 corresponding to the current sensors shown in the embodiments. The current sensor 103a detects an R-phase current signal. The current sensor 103b detects a T-phase current signal. Also, the voltage sensor 201a detects a voltage signal between the R phase and the S phase. Voltage sensor 201b detects a voltage signal between the T phase and the S phase.

The power calculation unit 202 multiplies the current signal of the current sensor 103a and the voltage signal of the voltage sensor 201a to generate an instantaneous power signal, smoothes this signal with a low-pass filter to obtain the active power, and calculates the current of the current sensor 103b. The instantaneous power signal is generated by multiplying the signal and the voltage signal of the voltage sensor 201b, the active power is obtained by smoothing this with a low-pass filter, and the active power obtained by adding each active power is calculated as the electric energy. The output unit 203 displays or externally outputs the calculated power amount.

The three-phase power P obtained by the two-wattmeter method is
P = VRS · IR + VTS · IT
=(VR-VS)*IR+(VT-VS)*IT
= VR · IR + VS · (-IR - IT) + VT · IT
= VR · IR + VS · IS + VT · IT
, which is the same as obtaining the power obtained by summing the power of each phase.

In addition, each configuration illustrated in the above embodiment is a functional schematic, and does not necessarily need to be physically configured as illustrated. In other words, the form of dispersion/integration of each device and component is not limited to the illustrated one, and all or part of them can be functionally or physically distributed/integrated in arbitrary units according to various usage conditions. can be configured

Reference Signs List 1, 10 current bars 2a, 2b magnetic collecting cores 2c, 2d inner surface 3 substrates 3a, 3b pattern coils 11, 11', 12, 12' coupling current bars 20 through holes 22a, 22b external connection terminals 30 positioning mechanisms 31 to 35 recesses 31a, 32a, 33a, 34a Claw 100 Case 103a, 103b Current sensor 200 Watt-hour meter 201a, 201b Voltage sensor 202 Electric energy calculation unit 203 Output unit a1, a2, b1, b2, c1, c2, d1, d2 Via AR Direction C Center G Gap I Current IR, IS, IT Three-phase current L Edge LD Load P Three-phase power P1, P2 Connection point r Radius SP Power source VR, VS, VT Three-phase voltage Φ Magnetic flux

Claims (6)

The magnetic A current sensor that detects the current flowing through the current bar based on the magnetic detection result detected by the detection unit,
Two coupling current bars respectively coupled to both ends of the current bar extend from at least the coupling point between the current bar and the coupling current bar to the longitudinal end of the magnetic core. A current sensor, wherein the current sensor is arranged parallel to the magnetic flux collecting core in the longitudinal direction. a current bar through which a current to be detected flows; at least two or more magnetic collecting cores for collecting magnetic flux generated by the current flowing in the current bar; and a substrate having at least two or more magnetic detection units, A current sensor that detects the current flowing through the current bar based on the magnetic detection result detected by the detection unit,
The current bar is arranged perpendicular to the longitudinal direction of the magnetic cores through a gap formed between the magnetic cores, and a through hole through which the substrate penetrates is formed in the gap,
The magnetic detection unit of the substrate is arranged on both sides of the through hole through the through hole,
Two coupling current bars respectively coupled to both ends of the current bar extend from at least the coupling point between the current bar and the coupling current bar to the longitudinal end of the magnetic core. A current sensor, wherein the current sensor is arranged parallel to the magnetic flux collecting core in the longitudinal direction. 3. The current sensor according to claim 1, wherein said magnet collecting core, said current bar and said substrate are fixed by a positioning mechanism formed in a housing. The current sensor according to any one of claims 1 to 3, wherein the two or more magnetic detection units are pattern coils formed on the substrate. The current sensor according to any one of claims 1 to 4, wherein the two or more magnetic detection units are pattern coils formed on the same plane on the substrate. The amount of electric power flowing through the current bar is calculated based on the current signal detected by the current sensor according to any one of claims 1 to 5 and the voltage signal detected by the voltage sensor. Total.

Images