JPH10177926A - Dc current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC current sensor having the excellent high volume productivity with the simple constitution, which is effective as a control sensor for charging/discharging a battery in an electric automobile and the like, has the excellent zero-point accuracy and temperature characteristics and can measures the DC currents in the wide range from the small current to the large current. SOLUTION: The core constituting body comprising a detecting core 2 and an exciting core 4, around which a detecting coil 3 and an exciting coil 5 are wound and arranged, is arranged in a ring-shape insulating case 8 forming a hollow part in communication with the circumferential direction. A feedback coil 7 is wound and arranged in a troidal shape at the outer surface part of the ring-shaped insulating case 8. The exciting coils 4 are arranged at the symmetrical positions with respect to the center of the axial direction of the detecting core 2 at least at a four places of the outer surface part of the detecting core 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a DC current sensor disposed in various devices using DC current, and more particularly, to an effective sensor as a sensor for managing a charge / discharge amount of a battery in an electric vehicle or the like. The present invention relates to a DC current sensor having excellent zero point accuracy and temperature characteristics, capable of measuring a wide range of DC current from a small current to a large current, and having a simple configuration and excellent mass productivity.

[0002]

2. Description of the Related Art Conventionally, as a DC current sensor,
A configuration employing a shunt resistance method, a mag amplifier method, a magnetic multivibrator method, a Hall element method, or the like is known. However, these DC current sensors are not only complicated in configuration, but also difficult to employ in earth leakage breakers, etc., which inherently require the detected conductor to pass through one turn. It was impossible to measure. The applicant of the present invention has a relatively simple structure as a DC current sensor that solves the above-described problems, and in particular, has a high sensitivity DC current having excellent detection capability even for minute current changes. A sensor was proposed earlier (Japanese Patent Laid-Open No. 6-74978).

For example, as shown in FIG. 12, a pair of detection coils 3a and 3b which are electrically connected to each other are formed in a toroidal shape on a short side at a position facing a detection core 2 made of a soft magnetic material having a rectangular frame shape. And the detection target wire 1 through which a DC current flows is disposed inside the detection core 2. Further, as means for switching the magnetic flux Φ ₀ in the detection core 2 generated based on the DC current I flowing through the detection target wire 1, a long side at a position opposed to the detection core 2 is provided in the circumferential direction of the detection core 2. A pair of excitation cores 4a and 4b made of a soft magnetic material and connected in a right angle direction to form a quadrangular cylindrical shape are arranged, and an excitation coil 5 is wound around the detection core 2 in the circumferential direction.

In such a configuration, when a DC current I flows through the conductor 1 to be detected, a magnetic flux Φ ₀ is generated in the detection core 2. At this time, a predetermined AC current (frequency f ₀ ) is applied to the exciting coil 5. When flowing, an alternating magnetic flux is generated in the exciting cores 4a and 4b in the α direction in the figure, and the alternating magnetic flux saturates the orthogonal portion 6 between the detecting core 2 and the exciting cores 4a and 4b. flux [Phi ₀ becomes to be switched, the frequency is modulated alternating magnetic flux twice the excitation frequency (2f _0). Electromotive force of the magnetic flux Φ frequency 2f ₀ in proportion to the DC current I flowing through the lead wire being detected 1 with changes in ₀ (V
_DET ) is detected by the detection coils 3a and 3b, and as a result, the absolute value of the DC current I flowing through the detected conductor 1 can be known.

The DC current sensor shown in FIG. 13 has been proposed for the purpose of simplifying the structure of the core and having a high S / N ratio, and has an annular soft structure in which the detection coil 3 is wound in a toroidal shape. The detection core 2 made of a magnetic material is formed in a tubular shape, and the excitation coil 5 is wound and disposed in a hollow portion communicating with the detection core 2 in the circumferential direction.
198754).

In such a configuration, when a DC current I flows through the detected conductor 1, a magnetic flux Φ ₀ is generated in the detection core 2. At this time, a predetermined exciting current (AC current) flows through the exciting coil 5. And an alternating magnetic flux in the direction α in the drawing is generated in the detecting core 2, and the alternating magnetic flux periodically magnetically saturates substantially the entire area of the detecting core 2, and the magnetic flux Φ ₀ in the detecting core 2 is switched. Becomes In this configuration, the detection core 2 also serves as the excitation core, but it is necessary to know the absolute value of the DC current I flowing through the detected wire 1 basically in the same manner as the operation principle of the DC current sensor of FIG. Can be.

In the DC current sensor having the above-described structure, the means for switching the magnetic flux Φ ₀ in the detection core generated based on the DC current I flowing through the conductive wire 1 to be detected includes:
The magnetic flux Φ ₀ is periodically cut off by forming a magnetically saturated region by the alternating magnetic flux in a part or the whole of the detection core 2 in the circumferential direction, and the basic operation principle is the same. All of the DC current sensors proposed by the applicant of the present application have a relatively simple structure, and in particular, have a configuration that has excellent detection capability even for a small change in current.
The use of DC current sensors has been greatly expanded.

However, a sensor for controlling the amount of charge / discharge of a battery in an electric vehicle accurately measures a very wide range from a small current at the time of charging the battery to a large current at the time of traveling, and integrates after time integration. It is required to minimize errors. In the configuration of the DC current sensor described above, the magnetic permeability of the core material flows through the wire to be detected due to the nonlinearity and magnetic saturation of the BH curve inherently included in the soft magnetic material constituting the detection core. The DC current I is not constant, and it is difficult to measure a required wide range of current with high accuracy.

As a configuration for solving such a problem, the applicant of the present application has a configuration of a conventionally known zero-flux control type DC current sensor using a Hall element and the above-mentioned DC which the applicant has previously proposed. We examined how to effectively combine the configuration of the current sensors, and confirmed that the advantages of each DC current sensor could be used effectively and that more than expected effects could be obtained.

That is, a conventionally known zero flux control type DC current sensor using a Hall element is shown in FIG.
As shown in FIG. 4, a magnetic flux Φ _f in a direction to cancel the magnetic flux Φ ₀ in the detection core 12 generated based on the DC current I flowing through the detected conductor 11 is generated, and the output of the Hall element 13 is made substantially zero. The feedback coil 14 is connected to the detection core 12
The to-be-detected conductor 1 is wound in a toroidal shape, and a current applied to the feedback coil 14 is measured.
1 is configured to detect a direct current I flowing through the device 1.

In this configuration, the measurement range and the measurement accuracy are determined by the characteristics of the Hall element 13, and a relatively wide range of measurement is possible. The required accuracy in the current range could not be secured.

However, with the DC current sensor proposed by the applicant of the present invention, it is not possible to perform a wide range measurement while maintaining high accuracy, but it is possible to realize a very high sensitivity measurement in a small current region. It has been found that an unexpected effect can be obtained by using these configurations in combination.

In the DC current sensor shown in FIG. 15, the arrangement of the detection core, the excitation core, the detection coil, and the excitation coil is the same as the conventional configuration shown in FIG. 12, except that the feedback coil 7 is arranged.

In such a configuration, when a DC current I flows through the conductor 1 to be detected, a magnetic flux Φ ₀ is generated in the detection core 2. At this time, a predetermined AC current (frequency f ₀ ) is applied to the exciting coil 5. When flowing, an alternating magnetic flux is generated in the exciting cores 4a and 4b in the α direction in the figure, and the alternating magnetic flux saturates the orthogonal portion 6 between the detecting core 2 and the exciting cores 4a and 4b. flux [Phi ₀ becomes to be switched, the frequency is modulated alternating magnetic flux twice the excitation frequency (2f _0). Electromotive force of the magnetic flux Φ frequency 2f ₀ in proportion to the DC current I flowing through the lead wire being detected 1 with changes in ₀ (V
_DET ) is detected by the detection coils 3a and 3b.

In this state, the detection coils 3a, 3b
The feedback coil generates a magnetic flux Φ _f in a direction to cancel the magnetic flux Φ ₀ until the electromotive force (V _DET ) detected in the detection core 2 becomes zero, that is, until the magnetic flux Φ ₀ generated in the detection core 2 becomes zero. 7, a predetermined DC current i is passed through and the current value is measured, so that the absolute value of the DC current I flowing through the detected conductor 1 can be obtained as a result (i = I / Nf).
Nf: number of turns of the feedback coil 7).

In the DC current sensor having the above configuration, the measurement is performed in a state where the magnetic flux Φ ₀ generated in the detection core 2 is substantially zero. By selecting a soft magnetic material having a high magnetic permeability and a low coercive force as the detection core 2, the zero point accuracy can be secured in a wide range from a small current to a large current, and the temperature change of the magnetic characteristics of the core material can be achieved. The temperature characteristics of the direct current sensor due to this can be greatly improved.

In the conventional DC current sensor shown in FIG. 13, the same effect as described above can be obtained by arranging the feedback coil in a toroidal shape around the outer periphery of the tubular detection core 2.

[0018]

As described above, by effectively arranging the feedback coil in the direct current sensor proposed by the applicant of the present invention, it is possible to maintain a high accuracy and maintain a high accuracy from a small current to a large current. Although a wide range of DC current can be measured, when the DC current I flowing through the detected wire 1 is a large current, the magnetic flux Φ _f generated in the direction to cancel the magnetic flux Φ ₀ generated in the detection core 2 is increased. The number of turns of the feedback coil is inevitably several thousand turns or more.

For example, in the configuration of FIG. 15, since the detection core 2 has a rectangular frame shape, it is difficult to mechanically wind and arrange the feedback coil. Need to be improved.

Further, in the DC current sensor having the configuration shown in FIG. 13, although the tubular detection core 2 has an annular shape, it is easy to mechanically wind and arrange the feedback coil. The core itself generates heat due to the eddy current generated by the coil and easily stays in the detection core 2, causing a temperature change in the detection core 2 itself. Even if the arrangement of the feedback coil can reduce the influence of the temperature change, the core itself can be reduced. This is not necessarily a preferable configuration because there is a possibility that thermal runaway occurs due to the heat generated by the heat generation and the Curie point may be exceeded.

The present invention is proposed in view of the above situation, and does not impair the essential advantages of the DC current sensor having the configuration proposed by the applicant of the present invention. Effective as a battery charge / discharge control sensor, has excellent zero point accuracy and temperature characteristics, can measure a wide range of direct current from small current to large current, and has excellent mass productivity with a simple configuration. It is intended to propose a DC current sensor.

[0022]

Means for Solving the Problems The inventors of the present invention have studied various configurations to achieve the above object, and as a result, have achieved the object by devising the shape of the detection core and the arrangement of the excitation core. Was found to be possible. That is, in order to enable the feedback coil to be mechanically wound and arranged, the detection core itself needs to be annular or polygonal annular, and the excitation core arranged on the outer periphery of the detection core also requires high-precision measurement. To achieve this, considering the overall electromagnetic balance, it is preferable that each excitation core is electrically insulated or that the electric resistance is high so that eddy current does not easily flow. It has been found that it is necessary to form a ring by connecting the detection core at a position symmetrical with respect to the center in the axial direction of the core in a direction perpendicular to the circumferential direction of the detection core.

Note that the DC current sensor having the above-described configuration including the detection core and the excitation core has the same or higher quality as the DC current sensor previously proposed by the present applicant in a specific measurement range even when the feedback coil is not provided. Since it has characteristics and the detection coil can be wound and arranged mechanically, it has been confirmed that it has great industrial value.

The present invention is based on the above findings, and includes a detection core made of an annular or polygonal annular soft magnetic material through which a detected wire through which a direct current flows flows, and an outer peripheral portion of the detection core. An exciting core made of a soft magnetic material that is connected to the detection core in the direction perpendicular to the circumferential direction at a position that is symmetrical with respect to the center of the detection core in at least four places, and that forms an annular shape; A DC current sensor comprising: a detection coil wound in a toroidal shape; and an excitation coil wound in a circumferential direction of an outer peripheral portion of the detection core.

[0025] Further, as a configuration capable of measuring a wide range of DC current from a small current to a large current, a detection made of a ring-shaped or polygonal ring-shaped soft magnetic material in which a wire to be detected through which a DC current flows is penetrated. The core is made of a soft magnetic material which is connected at a position symmetrical with respect to the axial center of the detection core at least at four or more locations on the outer periphery of the detection core in a direction perpendicular to the circumferential direction of the detection core to form an annular shape. An excitation core,
A detection coil that is wound around the detection core in a toroidal shape, an excitation coil that is wound around the detection core in the circumferential direction, and a DC that is wound around the detection core in a toroidal shape and flows through the detected wire. The present invention proposes a direct current sensor having a feedback coil that generates a magnetic flux in a direction to cancel a magnetic flux generated in a detection core based on an electric current and makes the output of the detection coil substantially zero.

As a more specific configuration, a core structure composed of a detection core and an excitation core, in which the above-described detection coil and excitation coil are wound and arranged, is formed into an annular shape forming a hollow portion communicating in the circumferential direction. A direct current sensor, wherein the detection coil is disposed in an insulating case and a feedback coil is wound around the outer periphery of the annular insulating case in a toroidal shape, or in such a configuration, the detection coil is arranged at the outer periphery of the annular insulating case. We propose a DC current sensor with a winding arrangement.

As a particularly preferable configuration of the detection core and the excitation core, the detection core is made of a regular octagonal ring-shaped soft magnetic material, and the excitation core is formed at every four sides in the circumferential direction of the detection core. We propose a DC current sensor characterized by the following.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION In the DC current sensor of the present invention, that the detection core and the excitation core are ring-shaped means that a closed circuit is electromagnetically formed, and the detection core is formed by mechanically winding a feedback coil. In order to enable the arrangement, it is necessary to form an annular or polygonal ring. However, the shape of the excitation core is not particularly limited to the shape of the embodiment (square tube).

The soft magnetic material constituting the detection core and the excitation core needs to be selected in consideration of the magnetic properties and the workability according to the detection sensitivity required for the DC current sensor. Known soft magnetic materials such as steel plate, amorphous, electromagnetic soft iron, and soft ferrite can be used, but permalloy is most preferable in terms of both magnetic properties and workability.

In mass-producing the DC current sensor of the present invention, the detection coil and the exciting coil are wound and arranged in order to secure electrical insulation of the feedback coil and facilitate mechanical winding arrangement. A core structure composed of a detection core and an excitation core is arranged in an annular insulating case forming a hollow portion communicating in the circumferential direction, and a feedback coil is wound around the annular insulating case in a toroidal shape. It is desirable to adopt a configuration.

From this point of view, as a result of studying an electromagnetically favorable balance and efficient placement in the annular insulating case, the excitation core was found to be at least four or more at the outer periphery of the detection core. It is necessary to arrange at a position symmetrical with respect to the center of the detection core in the axial direction.
It is also possible to appropriately select and arrange the number of places, eight places, and the like. However, disposing more than necessary is substantially equivalent to FIG.
The degree shown in the drawing is preferable because there is no difference from the configuration of No. 3 and the desired effect cannot be obtained.

FIGS. 4 to 8 show one embodiment of the detection core and the excitation core constituting the DC current sensor of the present invention. In each case, 2 indicates a detection core, 4 indicates an excitation core, and 8 indicates an annular insulating case. The detection coil, the excitation coil, and the feedback coil are not shown in these drawings.

FIG. 4 shows the detection core 2 formed in an annular shape. The detection core 2 is located at four positions on the outer periphery of the detection core 2 symmetrically with respect to the center in the axial direction of the detection core 2 with respect to the circumferential direction of the detection core 2. An excitation core 4 made of a soft magnetic material that is connected in a right angle direction to form an annular shape is arranged. As described above, the excitation core 4 can be appropriately selected and disposed at six positions, eight positions, or the like as long as the position is symmetrical with respect to the center of the detection core 2 in the axial direction as necessary. It is on the street.

FIGS. 5 to 7 show a configuration in which the detection cores 2 are square, regular hexagonal, and regular octagonal, respectively, and the excitation cores 4 are arranged on each side in the circumferential direction.

FIG. 8 is the same as FIG. 7 in that the detection core 2 is made of a regular octagonal ring-shaped soft magnetic material, but excitation cores are provided at every four sides in the circumferential direction of the detection core. This is a configuration that can achieve the effects of the present invention most effectively.

In FIGS. 5 to 8 described above, the configuration in which the detection core is a regular polygon is described. However, the excitation core is symmetrical with respect to the center of the detection core in the axial direction at least at four or more locations on the outer periphery of the detection core. If it is a configuration that can be arranged at the position where
It is not limited to regular polygons.

Further, details of the DC current sensor of the present invention will be described by taking the core configuration shown in FIG. 8 as an example. When the core configuration shown in FIG. 8 is adopted, as shown in the perspective view of FIG.
A quadrangular cylindrical excitation core 4 is formed at every other four sides of the detection core 2 made of a soft magnetic material having a regular octagonal annular shape in the circumferential direction. 5 and the detection coil 3 is wound around the detection core 2 in a toroidal shape.

In the figure, the detection coil 3 is substantially 4
Although the configuration is shown in which only one of the four exciting cores 4 is arranged on the outer periphery, the winding core may be wound around the outer periphery of each of the four exciting cores 4 and the exciting core 4 is formed. The detection core 2 may be wound around the four sides. Further, the configuration in which the detection coil 3 is wound around the outer periphery of the annular insulating case 8 has the same function and effect. In this case, it is desirable that the detection coil 3 is arranged at a symmetrical position around the outer periphery of the annular insulating case.

A core structure composed of the detection core and the excitation core in which the detection coil and the excitation coil are wound and arranged is disposed in an annular insulating case forming a hollow portion communicating in the circumferential direction. When the feedback coil is disposed in a toroidal shape around the outer periphery of the insulating case, the configuration shown in FIGS. 1 and 2 is obtained. FIG. 1 shows the annular insulating case 8 and the feedback coil 7 by two-dot chain lines in order to clarify the relationship with the above-mentioned core structure. FIG. 2 is a longitudinal sectional view,
This corresponds to the AA cross section in FIG.

In FIG. 1, the feedback coil 7 is shown to be wound around a part of the outer periphery of the annular insulating case 8. However, in practice, as described above, the feedback coil 7 has several thousand turns. It is wound in multiple layers over the entire outer periphery of the annular insulating case 8.

In such a configuration, when a DC current I flows through the conductor 1 to be detected, a magnetic flux Φ ₀ is generated in the detection core 2. At this time, a predetermined AC current (frequency f ₀ ) is applied to the exciting coil 5. flow and the alternating magnetic flux generated in the drawing α direction exciting core 4 parts, orthogonal part 6 of the detecting core 2 and the exciting core 4 by the alternating magnetic flux is magnetically saturated, the magnetic flux [Phi ₀ of said detecting core 2 Is switched, and the frequency is modulated into an alternating magnetic flux twice (2f ₀ ) the excitation frequency. The DC current I flowing through the detected wire 1 with the change of the magnetic flux Φ ₀
The detection coil 3 detects an electromotive force (V _DET ) having a frequency 2f ₀ that is proportional to.

In this state, the direction of canceling the magnetic flux Φ ₀ until the electromotive force (V _DET ) detected by the detection coil 3 becomes zero, that is, until the magnetic flux Φ ₀ generated in the detection core 2 becomes zero. the flow of the magnetic flux Φ predetermined DC current to the feedback coil 7 to generate a _f i, by measuring the current value, it is possible to know the absolute value of the DC current I flowing through the lead wire being detected 1 as a result (i = I / Nf Nf:
The number of turns of the feedback coil 7). Thus, the operation principle is the same as that of the DC current sensor shown in FIG.

In particular, in this configuration, the excitation core is
Since it is arranged at four positions on the outer periphery of the detection core and symmetrical with respect to the center of the detection core in the axial direction, electromagnetic balance is good, strong against external noise such as terrestrial magnetism, and stable. And the excitation cores adjacent to each other are arranged independently of each other, so that the influence of the eddy current of each of the coil excitation cores is reduced, and the influence of the temperature change of the core itself on the measured value is reduced. It has stable temperature characteristics even in a wide range of current measurement.

Further, in the conventional zero-flux control type DC current sensor using the Hall element, the portion where the Hall element is disposed becomes a magnetic gap as a detection core, the magnetic resistance of the core is high, and it is detected by the current to be measured. The magnetic flux generated in the core was reduced. In the DC current sensor of the present invention, the detection core 2 is a completely closed magnetic circuit,
It was confirmed that the magnetic resistance of the core was low, the magnetic flux generated in the detection core by the current to be measured was large, and the conversion efficiency was high.

Further, it was confirmed that the structure was strong against external noise such as terrestrial magnetism and was effective from the viewpoint of stability and the like. Although the configuration and operation principle of the DC current sensor of the present invention have been described with reference to the case of the core configuration of FIG. 8, the same effects as those of the core configuration of FIG. 8 can be obtained in any of the core configurations of FIGS. Can be.

[0046]

EXAMPLE In order to confirm the effect of the present invention, a DC current sensor shown in FIG. 1 was prepared. That is, thickness 0.3
5 mm Permalloy C (78% Ni-5% Mo-4% C
Press-punching a core component having a belt-shaped detection core 2 component and an excitation core 4 component connected at right angles to the longitudinal direction of the detection core 2 component at predetermined intervals from a u-balFe) plate. After the bending process, a predetermined portion is further fixed by spot welding, and the detection core 2 as shown in FIG. A quadrangular cylindrical excitation core 4 was formed at the location.

The length L of one side of the detection core 2 is 14 mm; the height H of the detection core 2 and the excitation core 4 is 6 mm;
Was W = 2 mm. These were subjected to a predetermined heat treatment to complete the detection core 2 and the excitation core 4. Further, electrical insulation is secured on the outer periphery of the detection core 2 so that the excitation coil 5
The detection coil 3 is wound around the outer periphery of each of the four excitation cores 4. The excitation coil 5 was formed by winding a formal wire having an outer diameter of 0.18 mm for 30 turns.

A hollow body having an outer diameter of 45 mm, an inner diameter of 30 mm, a height of 8 mm, and a circumferentially communicating core structure composed of the detection core 2 and the excitation core 4 in which the detection coil 3 and the excitation coil 5 are wound and arranged. The feedback coil 7 is disposed in a toroidal shape around the entire periphery of the annular insulating case 8, and the detection coil 3 is formed of an enameled wire having an outer diameter of 0.3 mm. The turns were wound and arranged in a toroidal shape. The feedback coil 9 has a configuration in which a formal wire having an outer diameter of 0.3 mm is wound 4000 turns.

A detection conductor 1 made of vinyl coating and having an outer diameter of 16 mm is penetrated in the detection core 2 (in the annular insulating case 8), and is fed back together with the detection coil 3 and the excitation coil 5 previously wound around the core. The DC current sensor of the present invention shown in FIG. 1 was completed by connecting the coil 7 to a predetermined electronic circuit. Note that the exciting current applied to the exciting coil 5 is f
= 4 kHz, AC current of 100 mArms.

FIGS. 9 and 10 show input / output characteristics of the DC current sensor of the present invention when a DC current is applied to the detection target wire 1 in a range of ± 400 A. FIG.
A linear characteristic can be obtained in a wider range, and the hysteresis is obtained even in a small current region (a range of ± 4 A in FIG. 10) which is a problem in the conventional zero-flux control type DC current sensor using the Hall element as shown in FIG. It was confirmed that high-precision measurement with almost no occurrence was possible.

FIG. 11 shows that a predetermined current (0.
2A, 0.6A, 1A) in the DC current sensor according to the present invention when the temperature is flowing (−40 ° C. to + 100 ° C.).
As is clear from the figure, it was confirmed that the measurement was almost flat and stable measurement was possible regardless of the temperature change.

In the measurement in the small current region, when the measurement based on the operation principle similar to that of the DC current sensor having the conventional configuration shown in FIG. 12 is performed without using the feedback coil 7, the characteristics shown in FIG. It was confirmed that almost the same or more measurement was possible. That is, in the core configuration of the present invention (for example, the configuration shown in FIG. 3), a high-sensitivity equivalent to or higher than the DC current sensor previously proposed by the applicant of the present application is used without using the feedback coil 7 for measuring the small current region. It was also confirmed that the measurement could be realized.

[0053]

As described above, in the DC current sensor of the present invention, a zero flux control type DC current sensor using a conventionally known Hall element and the DC current sensor previously proposed by the present applicant are used. By combining them effectively and devising the shapes and arrangements of the detection core and the excitation core, the advantages of each DC current sensor can be used effectively, and the simple configuration is excellent in mass productivity. Regardless, it has become possible to measure a wide range of direct current from a small current to a large current with high accuracy.

In particular, while solving the drawbacks of the conventionally known zero-flux control type DC current sensor using a Hall element, such as accuracy and temperature characteristics in a small current region, the applicant of the present invention has proposed the above. BH of a soft magnetic material constituting a detection core inherent in a DC current sensor
By solving the non-linearity of the curve and error factors due to the magnetic permeability, etc., it has become possible to provide a DC current sensor that achieves the desired characteristics.

Because of the features described above,
The direct current sensor of the present invention is particularly effective as a sensor for managing the charge / discharge amount of a battery in an electric vehicle or the like.

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view showing a configuration of a DC current sensor of the present invention.

2 is an explanatory longitudinal sectional view of FIG. 1 and corresponds to an AA section of FIG. 8;

FIG. 3 is a perspective explanatory view showing a core structure of the DC current sensor of the present invention.

FIG. 4 is a cross-sectional top view of the DC current sensor of the present invention.

FIG. 5 is an explanatory cross-sectional top view of the DC current sensor of the present invention.

FIG. 6 is an explanatory cross-sectional top view of the DC current sensor of the present invention.

FIG. 7 is an explanatory cross-sectional top view of the DC current sensor of the present invention.

FIG. 8 is an explanatory cross-sectional top view of the DC current sensor of the present invention.

FIG. 9 is a graph showing a relationship between a measured current and an output current.

FIG. 10 is a graph showing a relationship between a measured current and an output current.

FIG. 11 is a graph showing a relationship between a measured temperature and an output current.

FIG. 12 is a perspective explanatory view showing the configuration of a conventional DC current sensor.

FIG. 13 is an explanatory perspective view showing a configuration of a conventional DC current sensor.

FIG. 14 is a perspective explanatory view showing the operation principle of a conventional zero-flux control type DC current sensor using a Hall element.

FIG. 15 is a perspective explanatory view showing the configuration of a conventional DC current sensor.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 detection target wire 2 detection core 3, 3a, 3b detection coil 4, 4a, 4b excitation core 5 excitation coil 6 orthogonal section 7 feedback coil 8 annular insulating case

Claims (3)

[Claims] 1. A detection core made of a ring-shaped or polygonal ring soft magnetic material through which a detection target wire through which a direct current flows flows, and a detection core axial center at least at four or more outer peripheral portions of the detection core. An excitation core made of a soft magnetic material connected in a direction perpendicular to the circumferential direction of the detection core at a position symmetrical with respect to the detection core, and a detection coil wound and arranged in a toroidal shape on the detection core, A direct current sensor comprising: an exciting coil wound around an outer peripheral portion of the detection core. 2. A detection core made of an annular or polygonal annular soft magnetic material through which a detected wire through which a DC current flows flows, and a detection core axial center at least at four or more outer peripheral portions of the detection core. An excitation core made of a soft magnetic material connected in a direction perpendicular to the circumferential direction of the detection core at a position symmetrical with respect to the detection core, and a detection coil wound and arranged in a toroidal shape on the detection core, An exciting coil wound around the outer periphery of the detection core and a magnetic flux wound around the detection core in a toroidal shape and canceling a magnetic flux in the detection core generated based on a DC current flowing through the detected wire; And a feedback coil for causing the output of the detection coil to be substantially zero. 3. The detection core according to claim 1, wherein the detection core is made of a soft magnetic material having a regular octagonal ring shape, and the excitation core is formed at every four sides in the circumferential direction of the detection core. 2. The direct current sensor according to 2.