CN114127869A

CN114127869A - Shunt resistor and current detection device using same

Info

Publication number: CN114127869A
Application number: CN201980048049.5A
Authority: CN
Inventors: 大泽亮; 仲村圭史; 藤堂成浩
Original assignee: Koa Corp
Current assignee: Koa Corp
Priority date: 2018-07-26
Filing date: 2019-07-02
Publication date: 2022-03-01
Anticipated expiration: 2039-07-02
Also published as: KR102360792B1; WO2020021987A1; KR20210003251A; JP2020017678A; CN114127869B; JP7193941B2

Abstract

Disclosed is a shunt resistor using a Cu-Ni-Zn alloy containing nickel and zinc and having copper as a main component, as a resistance element material for a shunt resistor composed of a single-material resistance element.

Description

Shunt resistor and current detection device using same

Technical Field

The present invention relates to a shunt resistor and the like.

Background

In recent years, a current used in an electronic device has been developed toward a large current of, for example, about 1 kA. In this case, to ensure safety when the circuit is short-circuited, it is necessary to control the short-circuit current. When such control is realized with a shunt resistor, a structure capable of withstanding a large current at the time of a short circuit becomes an important part, and since a short-circuit current instantaneously occurs, instantaneous detection of the current also becomes an important part.

Therefore, the shunt resistor used in such applications is required to have a low resistance value, such as a resistance value of 100 μ Ω or less. In such a case, a measure may be considered to eliminate the connection between the electrode and the resistive element as much as possible, or to shorten the length of the resistive element as much as possible. Further, as a structure for eliminating the connection between the electrode and the resistance element, there is considered a measure in which the electrode and the resistance element are made of the same material such as Manganin (mangannin) (for example, see patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent application laid-open No. 2001-116771

Disclosure of Invention

Problems to be solved by the invention

However, when the electrodes of the shunt resistor and the resistance element are made of the same material (e.g., copper having a small resistivity), the resistance can be reduced, but there is a problem that TCR (temperature coefficient of resistance) becomes large.

In addition, when the electrodes of the shunt resistor and the resistive element are made of the same material, such as germanine (magnanin, Zeranin) whose TCR is small, although TCR can be reduced, there is a problem that residual resistance (resistance value of the outside portion of the voltage measurement terminal) becomes large and power consumption becomes large.

Further, when the electrode and the resistive element are made of different materials, there is a problem that the mechanical strength of the connection (e.g., welding) of the electrode and the resistive element is deteriorated.

The invention aims to provide a shunt resistor having a low resistance and a low TCR, the resistor element and the electrodes being made of the same material.

Another object of the present invention is to provide a current detection device using the shunt resistor, which is suitable for detecting a large short-circuit current.

Means for solving the problems

According to one aspect of the present invention, there is provided a shunt resistor comprising a single-material resistance element, in which a Cu — Ni — Zn alloy containing nickel and zinc as a main component of copper is used as a resistance element material.

Preferably, the Cu-Ni-Zn alloy has Ni content of 1.5-10 wt%, Zn content of 0.1-12 wt%, and the balance of Cu.

Preferably, the silicon-containing alloy further contains 0.3 to 0.9 wt% of Si. The Cu-Ni-Zn alloy may further contain 0.1 to 1 wt% of at least one metal selected from Sn and Mg.

The Cu-Ni-Zn alloy may further contain 0.1 to 1 wt% of at least one metal selected from Si, Sn, Mg, and Ti.

According to the present invention, in the shunt resistor described in any one of the above-described embodiments, the pair of voltage detection terminals is formed by raising a part of the plate-like object made of the single-material resistance element toward the front side.

The present invention also provides a current measuring apparatus comprising: the shunt resistor described above; and a current measuring circuit for measuring a current based on signals of a pair of voltage signal lines including first and second voltage signal lines connected to the pair of voltage detection terminals, respectively.

The present specification contains the disclosure of japanese patent application No. 2018-140647, which is the basis of the priority of the present application.

Effects of the invention

According to the present invention, it is possible to make the resistance element and the shunt resistor made of the same material as the electrode have a lower resistance and a lower TCR.

Drawings

Fig. 1 is a perspective view showing an exemplary structure of a shunt resistor according to a first embodiment of the present invention.

Fig. 2 is a perspective view showing an example structure of a current detection device using a shunt resistor according to a second embodiment of the present invention, before the shunt resistor is mounted on a circuit board.

Fig. 3 is a perspective view showing an exemplary structure of a current detection device using a shunt resistor according to a second embodiment of the present invention, after the shunt resistor is mounted on a circuit board.

Fig. 4 is a cross-sectional view of the exemplary structure of fig. 3 taken along line IIIa-IIIb after mounting the shunt resistor to the circuit board.

Fig. 5 is a circuit diagram (block diagram) showing an exemplary configuration of a current detection device using a shunt resistor according to the present embodiment.

Fig. 6 is a perspective view of a shunt resistor according to a third embodiment of the present invention, which uses a Cu — Ni — Zn alloy as a material of a plate (resistance element).

Detailed Description

Hereinafter, a shunt resistor and a current detection device using the shunt resistor according to an embodiment of the present invention will be described in detail with reference to the drawings.

(first embodiment)

First, a first embodiment of the present invention will be explained. Fig. 1 is a perspective view of an exemplary structure of a shunt resistor according to the present embodiment.

As shown in fig. 1, the shunt resistor a according to the present embodiment is a shunt resistor formed of a flat plate-like long plate-like object 1 having the following composition, for example. When the flat plate-like object 1 is a single-material resistance element, a pair of

voltage detection terminals

11a, 11b spaced apart from each other in the longitudinal direction of the object 1 are formed in the shunt resistor a. The pair of

voltage detection terminals

11a, 11b may be simply formed by: the other three sides of the plate-like object 1 are cut through while keeping the first side at two opposite positions, and then pulled up to the front side with the first side of the two positions as a reference.

In the plate-like object 1, the region inside the first side (denoted by reference numerals L1 and L2) serves as the effective resistance element 3 in current detection, and the regions outside to both ends thereof serve as the

effective electrodes

5a and 5 b.

As shown in fig. 1, by forming the voltage detection terminal by bending and pulling up after cutting through the plate-like object 1, it is easy to shorten the interval and obtain a voltage detection terminal having a short length. In addition, the inductance value of the shunt resistor can be reduced.

Further, in addition to the example of fig. 1, the voltage detection terminal may be formed by erecting a pin-shaped terminal as a separate component on the plate-like object 1. The pin-shaped terminal can be fixed to the plate-like object 1 by welding the pin-shaped terminal to the surface of the plate-like object 1 or by inserting the pin-shaped terminal into a hole formed in the plate-like object 1.

In addition, in the shunt resistor shown in fig. 1, a pair of

openings

7a, 7b spaced apart from each other in the longitudinal direction of the plate-like object 1 are also formed, the openings being provided so as to be fixed to a bus bar, a wiring circuit board (not shown), or the like by bolts or the like.

The composition of the material forming the plate-like object 1 made of a single-material resistance element will be described below.

When the material of the plate 1 is, for example, copper (100%) having a usual composition, the intrinsic resistance (μ Ω/cm) is as low as about 1.72, but the TCR (ppm/° c) is as high as about 3970.

In addition, when manganin (registered trademark) was used as the material of the plate-like object 1, the TCR (ppm/° c) was as low as about ± 50, but the inherent resistance (μ Ω/cm) was as high as about 44. Further, when Zeranin30 (registered trademark) is used, TCR (ppm/° c) is as low as about ± 29, but inherent resistance (μ Ω/cm) is as high as about 29.

In the present embodiment, the plate 1 materials shown in the following table were used. According to the present embodiment, the intrinsic resistance of the plate-like object is 4 to 5, and the TCR is 1000 to 2000. That is, the intrinsic resistance was about 1/10 compared to manganin. The TCR of 1000-2000 is higher than manganin but lower than copper.

TABLE 1

Table 1 shows an example of the material of the plate-like object 1 according to the present embodiment. As shown in table 1, the main component of the material (alloy material) for forming the plate-like object 1 made of the single-material resistance element is copper, which is denoted as D1, and the content is, for example, 77 to 98.4 wt%. In addition to the main component copper, zinc (Zn) represented by B1 and Ni represented by a1 are contained in the present embodiment. In addition, at least one of Si, Sn, Mg and Ti, which is marked as C1, is contained in the alloy in an amount of 0 to 1 wt%. The content of zinc (Zn) is 0.1-12 wt%, and the content of Ni is 1.5-10 wt% (to 100 wt%). In addition, the alloy material of the invention may contain inevitable impurities.

The reason why the intrinsic resistance can be lowered is presumed to be the addition and alloying of Zn in consideration that manganin also contains, for example, about 2 wt% of Ni. According to the inventors' presumption, Zn is easily oxidized to form an oxide film ZnO. In the alloy mainly composed of Cu, by adding a small amount of Zn, the ZnO oxide film on the alloy surface forming the plate-like object 1 can function as a surface protective film for the base low-resistance metal copper, and the effect of reducing TCR can be obtained by containing Ni, as with manganin and the like. Hereinafter, the alloy used for the plate-like object of the present embodiment to which a certain amount of Zn is added will be referred to as Cu — Ni — Zn alloy.

In addition, at least one metal selected from Si, Sn, Mg and Ti may be added to the Cu-Ni-Zn alloy in an amount of 0 to 1 wt%. Such alloys are also known as Cu-Ni-Zn alloys.

The Cu-Ni-Zn alloy of the present embodiment has excellent high-temperature durability and stable characteristics when used. For example, in a 1000-hour standing test at a high temperature of 175 ℃, the resistance change shows only a small fluctuation within ± 0.5%.

Since copper and copper alloys other than the present embodiment generally have low high temperature stability and exhibit resistance fluctuation of more than ± 1% when oxidation occurs, the Cu — Ni — Zn alloy of the present embodiment can be said to have stable characteristics and good durability.

(second embodiment)

A second embodiment of the present invention will be explained below. Fig. 2 and 3 are oblique views of an exemplary structure of a current detection device using the shunt resistor according to the present embodiment, in which fig. 2 is an oblique view of an exemplary structure before the shunt resistor is mounted on a circuit board, and fig. 3 is an oblique view of an exemplary structure after the shunt resistor is mounted on the circuit board. Fig. 4 is a cross-sectional view of the exemplary structure of fig. 3 taken along line IIIa-IIIb after mounting the shunt resistor to the circuit board. Fig. 5 is a circuit diagram (block diagram) showing an exemplary configuration of a current detection device using a shunt resistor according to the present embodiment.

As shown in fig. 2 and 3, the current measuring device X is formed by connecting a shunt resistor a made of the Cu — Ni — Zn alloy of the first embodiment as the material of the plate-like object (resistance element) 1 to a current measuring circuit (e.g., a circuit including an amplifier circuit B). The amplifying circuit B is a circuit for amplifying the output signal of the shunt resistor a.

The connection of the shunt resistor a to the amplifier circuit B is achieved by inserting the

voltage detection terminals

11a, 11a provided upright on the shunt resistor a into through holes (through openings) 23a, 23B formed in the circuit board 21 of the amplifier circuit B. The circuit board 21 on which the amplifying circuit B is formed is a printed circuit board or the like on which an amplifying circuit (circuit board) for amplifying an output signal of the shunt resistor a is provided. Of these, reference numeral 35 is a terminal member for outputting a signal from the amplification circuit B to other control devices and the like.

By using the through

holes

23a, 23b of the circuit board 21 and by connecting the

voltage detection terminals

11a, 11b with solder, a connection manner in which circuit components such as amplifiers on the circuit board 21 and the shunt resistors a are adjacent to each other can be realized.

Further, according to the cross-sectional view of the current detection circuit of fig. 4, by forming the

voltage detection terminals

11a, 11b so as to bend and pull up the plate-like object 1 of the shunt resistor a after cutting through, the distance between the pair of

voltage detection terminals

11a, 11b can be shortened, and the formed terminal length can be made short. Further, the inductance value of the shunt can be reduced, and durability can be ensured.

As shown in fig. 5, the amplification circuit B includes, for example, a Δ Σ conversion analog isolation amplifier 25 based on a photocoupler, an electrostatic coupling capacitor C, or the like. The analog-to-digital converter 27 is provided on the output side of the Δ Σ conversion analog isolation amplifier 25 via the line L13. The first signal output terminal 11a and the second signal output terminal 11b of the shunt resistor a are connected to the two input terminals of the amplifying circuit through lines L11, L12, respectively.

The amplifier circuit B has input terminals, and these input terminals are connected to the Δ Σ conversion analog isolation amplifier 25 via resistors and the like. Further, a capacitor C is provided between the lines L11, L12 connected to the input terminals. In this way, normal state noise and the like entering the Δ Σ conversion analog isolation amplifier 25 can be reduced. The positive-phase input terminal of the Δ Σ conversion analog isolation amplifier 25 is connected to Vcc, and the negative-phase input terminal thereof is connected to GND 31.

By using the Δ Σ conversion analog isolation amplifier 25 based on a photocoupler, an electrostatic coupling capacitor, or the like, it is possible to achieve electrical isolation on the input side and the output side. In this way, it is possible to reduce the influence of noise on the pair of voltage signal lines (lines L11, L12) connected to the amplification circuit provided in the current measurement device X for signal amplification.

Further, according to the present embodiment, the output signal may be digitally output. Since the TCR characteristic of the shunt resistor a makes it unsuitable for use in applications requiring high-precision current detection, it is preferable to use the output signal as a digital signal to reduce the processing load on the control device side.

When the current value exceeds a predetermined value, a High (High) level is output, and when the current value is within the predetermined value, a Low (Low) level is output. The digital circuit used may be a simple circuit employing a comparator or the like. Further, the insulating function of the circuit can be realized by a simple component such as the above-described photocoupler.

In addition, the current detection circuit of the present embodiment may be added to other detection circuits. For example, a voltage detection circuit or the like may be provided, and the present invention can be applied to voltage detection or the like.

(third embodiment)

A third embodiment of the present invention will be explained below. This embodiment includes other implementations of the shunt resistor. Fig. 6 is a perspective view of a shunt resistor according to the present embodiment, in which a Cu — Ni — Zn alloy is used as a material of a plate-like object (resistance element) 1.

The shunt resistor D of the present embodiment also uses the Cu — Ni — Zn alloy elongated plate-like object 1, as in the first embodiment, but has a structure in which the central resistance element 3 region is raised upward by, for example, press working the vicinity of the center. The other structure is the same as that of fig. 1. The shunt resistor D having such a meander structure can be used by surface mounting on a circuit.

The shunt resistor of the present embodiment can be further miniaturized as compared with the first embodiment.

(fourth embodiment)

A shunt resistor according to a fourth embodiment of the present invention will be described below. The basic structure of the shunt resistor may be the same as any of the first to third embodiments.

Table 2 shows more specific examples of the composition ratios of the respective metal materials shown in table 1.

TABLE 2

Among the Cu-Ni-Zn alloys shown in Table 2, example 1-1 contains, for example, 1.5 to 4.0 wt% of Ni, 0.1 to 0.5 wt% of Zn, 0.3 to 0.9 wt% of Si, 0.1 to 1 wt% of at least one metal selected from Sn and Mg, and the balance of Cu (93.6 to 98 wt%) (total 100 wt%).

In this example, the intrinsic resistance is 4 to 5 μ Ω · cm, and the TCR is about 1000 to 2000.

Further, examples 1-2 contained, for example, 1.6 wt% of Ni, 0.4 wt% of Zn, 0.4 wt% of Si, 0.5 wt% of Sn, and the balance of Cu (about 97.1 wt%).

In this example, the intrinsic resistance was 4.3. mu. omega. cm, and the TCR was about 1500.

That is, since it corresponds to the case where the ratio of Cu is high in table 1, the intrinsic resistance is lower than both manganin and Zeranin30, and at the same time, the TCR value is higher than those of manganin and Zeranin 30. Therefore, the requirement for reducing the inherent resistance value is high.

(fifth embodiment)

A shunt resistor according to a fifth embodiment of the present invention will be described below. The basic structure of the shunt resistor may be the same as that of the first embodiment.

Table 3 shows a more specific example of the composition ratio of each metal material shown in table 1.

TABLE 3

Among Cu-Ni-Zn alloys shown in Table 3, example 2-1 contains, for example, 5 to 10 wt% of Ni, 5 to 12 wt% of Zn, 0 to 1 wt% of Si and/or Ti, and the balance of Cu (about 77 to 90 wt%).

In this example, the intrinsic resistance is 10 to 15 μ Ω · cm, and the TCR is about 200 to 1000.

In addition, example 2-2 contains, for example, 6 wt% of Ni, 11 wt% of Zn, and the balance of Cu (about 83 wt%).

In this example, the intrinsic resistance is 11.5. mu. omega. cm, and the TCR is about 600.

That is, since it corresponds to the case where the Cu ratio is low in table 1, the inherent resistance is lower than that of manganin, Zeranin30, but higher than that shown in table 2. At the same time, the TCR was higher than manganin, Zeranin30, but lower than in Table 2. Therefore, it is effective for the case where the resistance value needs to be reduced but the TCR is not desired to be excessively increased.

As mentioned above, by adding manganin, Zn, which is not contained in Zeranin30, to the alloy, lower resistance and lower TCR can be achieved.

According to the fourth and fifth embodiments, a shunt resistor having a TCR lower than copper and a resistance lower than manganin can be realized.

Therefore, according to this embodiment, in the shunt resistor in which the resistance element and the electrode are made of the same material, not only low resistance can be realized, but also good TCR characteristics can be obtained.

Further, as can be seen from comparison of tables 2 and 3, by adjusting the ratio of the added elements, a shunt resistor having a desired characteristic value can be manufactured to some extent.

In addition, according to the present embodiment, by determining the respective material compositions, it is possible to provide a shunt structure most suitable for short-circuit current detection.

In addition to this, by connecting the current detection device, a system capable of detecting a short-circuit current can be realized.

The above-described embodiments are not limited to the various configurations shown in the drawings, and may be appropriately modified within a range in which the effects of the present invention can be achieved. The present invention can be carried out with appropriate modifications without departing from the scope of the object of the present invention.

In addition, each component of the present invention may be arbitrarily selected or substituted, and all inventions having a structure obtained by such selection or substitution are also encompassed in the present invention.

Industrial applicability

The invention can be used for shunt resistors.

Reference numerals

A shunt resistor

B amplifying circuit

X current measuring device

1 sheet-like object

3 resistance element

5a, 5b electrode

11a, 11b voltage detection terminal

21 circuit board

23a, 23b through hole (through hole)

25 delta sigma conversion analog isolation amplifier

27A/D converter

All publications, patents and patent applications cited in this specification are herein incorporated in their entirety by reference into the specification.

Claims

1. A shunt resistor uses a Cu-Ni-Zn alloy containing nickel and zinc and having copper as a main component as a resistance element material for a shunt resistor composed of a single-material resistance element.

2. The shunt resistor of claim 1,

in the content of the Cu-Ni-Zn alloy

Ni is 1.5 to 10 wt%,

0.1 to 12 wt% of Zn,

the balance being Cu.

3. A shunt resistor according to claim 1 or 2, further comprising 0.3 to 0.9 wt% Si.

4. A shunt resistor according to any one of claims 1 to 3, further comprising 0.1 to 1 wt% of at least one metal selected from Sn and Mg.

5. The shunt resistor of claim 1, wherein the Cu-Ni-Zn alloy further contains 0.1 to 1 wt% of at least one metal selected from Si, Sn, Mg, and Ti.

6. A shunt resistor according to any one of claims 1 to 5,

the pair of voltage detection terminals are formed by pulling up a part of the plate-like object made of the single-material resistance element toward the front side.

7. An electric current measuring apparatus, comprising:

the shunt resistor of claim 6; and

and a current measuring circuit for measuring a current based on signals of a pair of voltage signal lines including first and second voltage signal lines connected to the pair of voltage detection terminals, respectively.