JP2015057582A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor which allows output voltage from the current sensor to reach at least 90% of a final value when the current infused to a current line from a power source reaches to the final value.SOLUTION: The current sensor of the invention is configured so that a center of a magnetic detection element 22 is in a width direction vertical to the current flow of a current line 21, and is disposed on a position separated from a surface of the current line 21 by 0.43 W or more to a width W of the current line 21.

Description

  The present invention relates to a current sensor that measures a current to be measured by detecting a magnetic field generated around a current line through which the current to be measured flows.

  In recent years, there has been a demand for a current sensor for accurately measuring a large current on the order of several tens of A to several hundred A, such as a charge / discharge current of a battery of a hybrid car, an EV car, or the like, or a drive current of an electric motor. FIG. 8A is a perspective view showing a state in which a magnetic detection element of a conventional current sensor is placed on a current line. FIG. 8B is a sectional view of the magnetic detection element. 8 (a) and 8 (b), the magnetic detection element 1 is placed on a flat current line 2 whose dimension (width dimension) in the X-axis direction is several times or more of the dimension (thickness dimension) in the Y-axis direction. The sensor chip 5 is mounted and includes two magnetic flux converging plates 3A and 3B and two Hall elements 4A and 4B. The magnetic flux concentrating plates 3A and 3B are arranged on the surface of the sensor chip 5 at a predetermined interval, and the Hall elements 4A and 4B are arranged in regions where the magnetic flux density is increased by the magnetic flux converging plates 3A and 3B. .

  The magnetic flux 6 generated by the current I to be measured passes through the magnetic sensing element 1 from the one magnetic flux converging plate 3A through the one Hall element 4A and further through the other Hall element 4B and the other magnetic flux converging plate 3B. pass. The Hall elements 4A and 4B generate an electrical signal (Hall voltage) proportional to the density of the magnetic flux 6. The magnetic detection element 1 measures the measured current I by outputting an electric signal proportional to the magnetic flux density in the horizontal direction on the surface of the current line 2.

  Further, instead of the magnetic detection element including the magnetic flux converging plates 3A and 3B and the sensor chip 5 including the two Hall elements 4A and 4B, the magnetic resistance element includes a magnetoresistive element connected to form a bridge and a bias magnet. Similarly, the current I flowing through the current line 2 can be measured using the magnetic detection element.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

JP 2006-38834 A

  In the current line 2 as shown in FIG. 8A, the magnetic flux density vector generated in the vicinity of the planes 2A and 2B parallel to the XZ plane by the direct current I flowing through the current line 2 is the plane 2C parallel to the YZ plane. Except in the vicinity of 2D, it is horizontal to the X axis, and its size is inversely proportional to the distance from the surface of the current line 2 and is almost constant in the XZ plane. Further, as described above, the magnetic detection element 1 outputs an electrical signal proportional to the magnetic flux density in the X-axis direction. For this reason, the magnitude of the electrical signal output from the current sensor is inversely proportional to the distance from the surface of the current line 2 except in the vicinity of the surfaces 2C and 2D parallel to the YZ plane, and is substantially constant in the XZ plane.

  However, when the current I flowing through the current line 2 is unsteady, particularly when the current rises, the electric signal output from the current sensor does not follow the change in the current, and reaches the final value after a long time has passed. I found out that there was a phenomenon.

  In FIG. 9A, a power source V is connected to a flat copper current line 2 having a width W = 14 mm, a thickness t = 1.6 mm, and a length of 200 mm, and the current sensor is connected to the center of the current line 2 in the width direction. FIG. 3 is a schematic diagram showing a state where the center of the magnetic detection element 1 is placed. Here, R is a termination resistor. FIG. 9B shows the current a injected from the power source V to the current line 2 and the output voltage b from the current sensor superimposed over time. According to the experiment, the current a injected from the power source V to the current line reaches the final value 30A in 100 μsec, but the output voltage b from the current sensor reaches 90% of the final value. Required 240 μsec. That is, it takes 240 μsec-100 μsec = 140 μsec from when the current a injected from the power source V reaches the final value until the output voltage b from the current sensor reaches 90% of the final value. Met. After that, the difference between the time until the output voltage from the current sensor reaches 90% of the final value and the time until the current a injected from the power source V to the current line reaches the final value is the rise time of the current sensor. When the output voltage from the current sensor reaches 90% or more of the final value when the current a injected from the power source V to the current line reaches the final value, the rise time is zero. Define. Then, it was confirmed that the delay of the output voltage b from the current sensor with respect to the current a injected from the power source V to the current line is substantially constant regardless of the final current value. Even if the current injected from the power source V to the current line reaches a final value in 10 μsec, the time required until the output voltage b from the current sensor reaches 90% of the final value is substantially constant. I also confirmed that there was.

  In hybrid cars, EV cars, and the like, the number of rotations of the motor, the current capacity of the storage battery, and the like are controlled by detecting the value of the current flowing through the current line. Therefore, as described above, when a long time delay is required until the measured current value reaches the final value, such control cannot be performed properly, and the travelable distance is shortened. There were problems such as shortening the service life.

  FIG. 10 shows changes in the rise time when the center of the magnetic detection element 1 of the current sensor is moved from the center of the current line 2 toward the end. From this data, as the current sensor is moved from the center in the width direction of the current line to the end, the rise time decreases, the rise time becomes zero, and when the current sensor is further moved to the end of the current line, the rise time is again. It can be seen that it increases. However, since the rise time is only 0 in a narrow range of 1.5 mm, there is a problem that the position where the current sensor is disposed is limited and the usability is poor.

  The present invention solves the above-mentioned conventional problems, and by optimizing the height at which the magnetic detection element of the current sensor is disposed with respect to the current line, the response of the current sensor to the current flowing through the current line is increased. It is an object of the present invention to provide a current sensor that can reduce the restriction on the position in the width direction of the current line in which the current sensor is arranged.

  In order to solve the above problems, the present invention includes a magnetic detection element that detects a magnetic field generated by a current flowing through a flat current line, and measures the current based on the magnetic field detected by the magnetic detection element In the measuring apparatus, the center of the magnetic detection element is within a width direction perpendicular to the current flow of the current line, and from the surface of the current line to the width W of the current line. In this configuration, when the current injected from the power source to the current line reaches the final value, the output voltage from the current sensor is at least 90% of the final value. %, The substantial rise time can be reduced to zero, and a current sensor that can greatly relax the restriction on the position of the current sensor with respect to the current line can be provided. And it has a effect that.

  As described above, the present invention is a current measuring device that includes a magnetic detection element that detects a magnetic field generated by a current flowing through a flat current line, and that measures the current based on the magnetic field detected by the magnetic detection element. The center of the magnetic detection element is in the width direction perpendicular to the current flow of the current line, and from the surface of the current line, 0.43 W or more with respect to the width W of the current line. It is configured to be provided at a distant position so that when the current injected from the power source to the current line reaches the final value, the output voltage from the current sensor reaches at least 90% of the final value. It is possible to provide a current sensor capable of providing a current sensor that can substantially reduce the limit of the position in the width direction of the current line in which the current sensor is disposed, and can substantially reduce the rise time to zero. A.

(A) Schematic diagram showing time variation of current injected into current line, (b) Schematic diagram showing current density on current line surface at t = t ₁ , (c) On current line surface at t = t ₂ (D) Schematic diagram showing current density on current line surface at t = t ₃ Schematic diagram for estimating the magnitude of the x-direction magnetic flux density Bx at position A on the current line at t = t ₁ (A) Simulation of the time response of the x-direction component Bx of the magnetic flux density at a position separated by a predetermined distance h from the center of the widthwise surface of the current line of width W = 14 mm, thickness t = 1.6 mm, and length 200 mm. The figure which shows a result, (b) The figure which shows the simulation result of the rise time of x direction component Bx of magnetic flux density B with respect to the distance h from the center of the width direction surface of the same current line, (c) Y from the surface of the same current line The figure which shows the simulation result of the rise time of the x direction component Bx of the magnetic flux density in the position A which is 5.2 mm (h = 5.2 mm) in the axial direction and separated by the distance x in the X axis direction, (d) FIG. ) To (c) are schematic diagrams showing simulations (A) Schematic cross-sectional view showing a state in which the magnetic detection element of the current sensor is arranged at a position h = 6 mm from the center of the width direction surface of the current line having a width W = 14 mm, a thickness t = 1.6 mm, and a length of 200 mm. (B) The figure which shows the measurement result of the current waveform a inject | poured into a current line from a power supply, and the output voltage waveform b from a current sensor. (A) Top view of the magnetic detection element, (b) Vertical sectional view of the magnetic detection element (A) A simulation result of the rise time of the x-direction component Bx of the magnetic flux density at a position separated by a predetermined distance h from the center of the widthwise surface of the current line having a width W = 20 mm, a thickness t = 5 mm, and a length of 200 mm. (B) Rise of the x-direction component Bx of the magnetic flux density at a position separated by a predetermined distance h from the center of the widthwise surface of the current line having a width W = 40 mm, a thickness t = 2.5 mm, and a length of 200 mm Diagram showing time simulation results For the width W of each of the three current lines having different widths and thicknesses, the minimum distances hmin and W between the center of the magnetic detection element of the current sensor and the current line are such that the rise time of the current sensor is zero. Ratio, hmin / W actual values and simulation values are plotted (A) The perspective view which shows the state which mounted the magnetic detection element of the conventional current sensor on the current line, (b) Sectional drawing of the magnetic detection element (A) Schematic diagram showing a state where the center of the magnetic detection element is placed at the center in the width direction on a current line having a width W = 14 mm, a thickness t = 1.6 mm, and a length 200 mm, and (b) injection into the current line. Of measurement result of current a and output voltage b from current sensor The figure which shows the change of the rise time when moving the center of the magnetic detection element of the current sensor from the center of the current line toward the end

  First, as shown in FIG. 9, when the magnetic detection element 1 is arranged close to the center of the surface of the current line 2 in the width direction, when the current I flowing through the current line 2 is unsteady, The cause of the phenomenon that the electrical signal output from the current sensor does not follow the current change at the time of rising and reaches the final value after a long time will be qualitatively described with reference to the drawings.

FIG. 1A is a schematic diagram showing a time change of the current I injected into the current line 21 having the width W, and FIGS. 1B, 1C, and 1D show predetermined times (t ₁ , t _2). , T ₃ ) is a schematic diagram showing a current density J on the surface of the current line.

When current starts to flow through the current line 21 (t = 0) and the current flowing through the current line 21 increases at a constant rate with respect to time (0 <t <t ₁ ), each part in the current line 21 is caused by electromagnetic induction. Inductive magnetic flux is generated around the current flowing through. This induced magnetic flux is linked to the current in the current line 21 and generates a counter electromotive force in a direction that prevents the current from changing. The current at the center of the current line 21 has a larger number of interlinkage magnetic fluxes and a larger counter electromotive force, so that the current density is reduced and the current flows concentrically around the conductor. As a result, when 0 <t ≦ t ₁ , the state where the current density of the surface of the current line 21, particularly the corner portion, is large and the current density of the central portion of the current line 21 is small continues. FIG. 1B schematically shows the current density in the width direction of the current line 21 at t = t ₁ .

When the current flowing through the current line 21 reaches the final value and the current no longer increases (t ₁ ≦ t), the current density at the surface and corners of the current line 21 decreases, and at the center of the current line 21 As the current density rises, the current density of each part of the current line 21 is made uniform. However, if the current density at the surface and corners of the current line 21 is to be reduced, a counter electromotive force is generated again to suppress this change. Similarly, when the current density at the central portion of the current line 21 is to increase, a counter electromotive force is generated again to suppress this change. As a result, a certain elapsed time is required until the current density in the current line 21 becomes uniform. FIG. 1C schematically shows the current density in the width direction of the current line 21 at t = t ₂ after the current flowing through the current line 21 reaches the final value. And after sufficient time passes, the current density in the current line 21 becomes constant. FIG. 1D schematically shows the current density in the width direction of the current line 21 after a sufficient time has elapsed (t → ∞).

  When the current flowing through the current line 21 reaches the final value, as shown in FIG. 1B, the current density at the central portion of the surface in the width direction of the current line 21 is small, and the end portion of the surface in the width direction of the current line 21 Therefore, the magnetic flux density sensed at a position close to the surface of the current line 21 is dominantly affected by the current density immediately below the position, and becomes smaller at the central portion of the current line 21. As a result, the output voltage from the current sensor in which the magnetic detection element is arranged at the substantially central portion of the width direction surface of the current line 21 becomes small.

  Immediately after the current flowing in the current line 21 becomes constant, as shown in FIG. 1C, the current density in the central portion of the surface in the width direction of the current line 21 gradually increases, and the current in the width direction surface of the current line 21 increases. The current density at the edge gradually decreases. Along with this, the output voltage from the current sensor in which the magnetic detection element is arranged substantially at the center of the surface in the width direction of the current line 21 gradually increases and gradually approaches the final value.

  As described above, when the magnetic detection element is placed almost at the center of the surface in the width direction of the current line 21, when the current I flowing through the current line 21 is unsteady, particularly when the current rises, the electrical signal output from the current sensor is This is the cause of the phenomenon that the final value is reached after a long time without following the current change.

  We thought that this phenomenon could be avoided if the magnetic detection element was not placed on the current line 21 but placed at a certain distance from the surface of the current line 21.

The reason will be described with reference to FIG. FIG. 2 is a schematic diagram for estimating the magnitude of the x-direction magnetic flux density Bx at the position A on the current line 21 at the time of t = t ₁ in FIG. Here, the position A is assumed to be in the center on the surface in the width direction of the current line 21. Further, the magnitude of the current density on the surface of the current line 21 is represented by a number +.

In FIG. 2, the distance between the position A where the magnetic detection element is arranged and the central portion of the surface of the current line 21 is r, the width of the current line 21 is W, and the acute angle between the position A and the X axis is θ, and this will be briefly described. Therefore, assuming that the current flowing on the surface of the current line 21 is the current i ₁ at the center and the current at the end of the surface of the current line 21 is only i ₂ , the current i _{1 at} the center of the surface of the current line 21 The generated magnetic flux density B ₀ is expressed by Ampere's law, where k is a proportional constant.

It can be expressed as Further, the magnetic flux density B ₁ generated in the position A the current end of the current line 21 surface by i _2, and the x-direction component B ₁ ^x of the magnetic flux density B ₁ represents

It can be expressed as Therefore, the x-direction component Bx of the magnetic flux density B generated at the position A by the current line 21 is

It becomes.

When the position A is close to the current line 21, that is, when r is sufficiently small, the second term of Equation 4 is asymptotic to 0, so Bx is the first term, that is, the central portion of the surface of the current line 21. It depends on the current i ₁ .

  On the other hand, when the position A is away from the current line 21, that is, when r is sufficiently larger than W, if the total current flowing through the current line 21 is i, Equation 5

Thus, after the total current i becomes constant, it can be understood that the x-direction component Bx of the magnetic flux density B generated at the position A by the current line 21 is not affected by the current density distribution on the current line 21.

  From the above, if the magnetic detection element is not placed close to the surface of the current line 21 but is arranged at a certain distance from the surface of the current line 21, the x-direction component Bx of the magnetic flux density B generated at the position A by the current line 21. Is not only a contribution due to the magnetic flux density generated by the current flowing in the center portion of the surface of the current line 21 but also the contribution due to the magnetic flux density generated by the current flowing at the end portion of the current line 21 surface. The

  In order to verify this expectation, a simulation shown in FIG. FIG. 3A shows a setting in which a current is injected into a copper current line 21 having a width W = 14 mm, a thickness t = 1.6 mm, and a length of 200 mm so as to reach a final value of 30 A in 50 μsec. The change with respect to time of the x-direction component Bx of the magnetic flux density at a position away from the center of the surface in the width direction by a predetermined distance h is calculated.

  The following can be seen from FIG.

  (1) When the distance h = 0 mm from the center of the width direction surface of the current line 21 reaches the final value, the x-direction component Bx of the magnetic flux density B is 1.13 mT, which is 90% of the final value. It takes 125 μsec to reach. Thereafter, the difference between the time until the x-direction component Bx of the magnetic flux density B reaches 90% of the final value and the time until the current injected into the current line 21 reaches the final value is the x-direction component of the magnetic flux density B. This is called the rise time of Bx. It is considered that the coincidence between the measured rise time 140 μsec of the current sensor shown in FIG. 9B and the calculated 125 μsec rise time of the x-direction component Bx of the magnetic flux density B is considered good.

  (2) As the distance h from the center of the width direction surface of the current line 21 increases, the rise time of the x-direction component Bx of the magnetic flux density B decreases and the final value of the x-direction component Bx of the magnetic flux density B also decreases. . This is consistent with the above expectations.

  FIG. 3B is a diagram showing a simulation result of the relationship between the distance h from the center of the surface in the width direction of the current line 21 and the rise time of the x-direction component Bx of the magnetic flux density B. FIG. 3B shows that the rise time of the x-direction component Bx of the magnetic flux density B is zero when the distance h from the center of the surface in the width direction of the current line 21 is 5.2 mm or more, that is, the current injected into the current line 21 is When the final value is reached, it can be seen that the x-direction component Bx of the magnetic flux density B reaches 90% or more of the final value.

  In FIG. 3C, when the origin of the XY coordinates is placed at the center of the current line 21 in the width direction, it is 5.2 mm (h = 5.2 mm) in the Y-axis direction from the surface of the current line 21 and the distance x in the X-axis direction. That is, the rise time of the x-direction component Bx of the magnetic flux density at the position A separated by a distance is calculated. From FIG. 3C, it can be seen that if the position A is within the width direction of the current line 21, the rise time is always zero.

  FIG. 4A shows a magnetic detection element 22 of a current sensor at a position h = 6 mm from the center of the width direction surface of a flat current wire 21 made of copper having a width W = 14 mm, a thickness t = 1.6 mm, and a length 200 mm. It is a cross-sectional schematic diagram which shows the state which has arrange | positioned. FIG. 4B shows the current waveform a injected from the power source to the current line 21 and the output voltage waveform b from the current sensor superimposed on each other. From this experimental result, the output voltage b of the current sensor has reached 90% of the final value of the current sensor output at the time of 100 μsec when the current a injected into the current line 21 has reached the final value 30A. That is, it was confirmed that the rise time of the current sensor becomes zero. It was also confirmed that if the height from the surface of the current line 21 is fixed to 6 mm, the rise time of the current sensor becomes zero within the width direction of the current line 21.

  The magnetic detection element of the current sensor used in this experiment will be briefly described with reference to FIG. 5A is a top view of the magnetic detection element 22, and FIG. 5B is a longitudinal sectional view of FIG. 5A. Here, the lengths of the magnetic detection element 22 in the X-axis, Y-axis, and Z-axis directions are about 3 mm, 3 mm, and 1 mm, respectively.

  In FIG. 5, four electrodes of an application electrode 24, a first output electrode 25, a second output electrode 26, and a ground electrode 27 are formed on an insulating substrate 23. A meandering magnetoresistive element 28 a made of a magnetoresistor is formed between the application electrode 24 and the first output electrode 25. Similarly, between the first output electrode 25 and the ground electrode 27, between the application electrode 24 and the second output electrode 26, and between the second output electrode 26 and the ground electrode 27, a meandering magnetic field is formed. Resistive elements 28b, 28c, and 28d are formed. By making such an electrical connection, the magnetoresistive elements 28a, 28b, 28c, and 28d constitute a bridge circuit. The magnetoresistive elements 28a, 28b, 28c, and 28d are magnetoresistive thin films having a thickness of about 0.1 μm made of a ferromagnetic material such as Ni—Co. Further, in FIG. 5, the magnetoresistive element 28a has the longitudinal direction of the meandering pattern in the direction of 45 ° inclined obliquely to the upper right on the paper surface. The longitudinal direction of the meander pattern is located in a 45 ° direction inclined obliquely upward, and the angle between them is a right angle. The positional relationship between the magnetoresistive element 28c and the magnetoresistive element 28d is the same. Further, the positional relationship between the magnetoresistive element 28a and the magnetoresistive element 28c is the same. Here, the magnetosensitive directions of the magnetoresistive elements 28a, 28b, 28c, and 28d are perpendicular to the longitudinal direction of each meander pattern.

The insulating layer 30 is made of a SiO ₂ thin film having a thickness of about 1 μm, and electrically insulates the thin film magnet 31 described later by covering the magnetoresistive elements 28a, 28b, 28c, and 28d. The thin film magnet 31 is made of CoPt having a thickness of about 0.6 μm, formed on the insulating layer 30 by vapor deposition, sputtering, or the like, and then patterned by exposure and etching to have a plurality of substantially rectangular shapes having a longitudinal direction. It is divided into bodies. The direction of the generated magnetic field is the direction perpendicular to the longitudinal direction of the thin-film magnet 31, that is, the left-right direction in FIG. The thin film magnet 31 is divided into a plurality of substantially rectangular parallelepipeds having a longitudinal direction in a direction forming 45 ° with respect to the longitudinal direction of the pattern of the magnetoresistive elements 28a, 28b, 28c, and 28d. This direction is also a direction that forms 45 ° with respect to the magnetosensitive direction of the magnetoresistive elements 28a, 28b, 28c, and 28d. The magnetic field generated by the thin film magnet 31 is arranged in the same direction as the current flowing through the current line 21, that is, in the direction perpendicular to the magnetic field generated by the current to be measured flowing through the current line 21. Reference numeral 32 denotes an insulating layer made of a SiO ₂ thin film having a thickness of about 1 μm and covering the thin film magnet 31.

  From the above, if a change with time of the x-direction component Bx of the magnetic flux density at a position away from the center of the surface in the width direction of the current line 21 having a predetermined dimension by a predetermined distance h is simulated, the current sensor is located at this position. It was found that the rise time of the current sensor can be estimated when the center of the magnetic detection element 22 is placed. The “center of the magnetic detection element 22” here refers to the geometric center of the region surrounded by the magnetoresistive elements 28a, 28b, 28c, and 28d on the insulating layer 32 of the magnetic detection element 22 shown in FIG. is there.

  FIG. 6A shows a setting in which a current is injected into a copper current line 21 having a width W = 20 mm, a thickness t = 5 mm, and a length 200 mm so that the final value 30A is reached in 50 μsec. It is a figure which shows the result of having simulated the rise time of the x direction component Bx of the magnetic flux density in the position which only the predetermined distance h left | separated from the center of the direction surface. 6A, the distance h from the center of the surface in the width direction of the current line 21 is 8.4 mm or more, the rise time of the x-direction component Bx of the magnetic flux density B is 0, that is, the current injected into the current line 21 is When the final value is reached, the x-direction component Bx of the magnetic flux density B is expected to reach 90% or more of the final value.

  According to the experimental results, when the center of the magnetic detection element 22 of the current sensor is disposed at a position of 8.5 mm or more from the center of the surface in the width direction of the current line 21, the current a injected into the current line 21 is 100 μsec. When the value 30A was reached, it was confirmed that the output voltage b of the current sensor had reached 90% of the final value of the current sensor output, that is, the rise time of the current sensor was zero. It can also be confirmed that the rise time of the current sensor becomes zero within the width direction of the current line 21 if the height from the surface of the current line 21 at the center of the magnetic detection element 22 of the current sensor is 8.5 mm or more. It was.

  Similarly, FIG. 6B shows a setting in which a current is injected into a copper current line 21 having a width W = 40 mm, a thickness t = 2.5 mm, and a length 200 mm so that the final value 30A is reached in 50 μsec. FIG. 6 is a diagram showing the result of simulating the rise time of the x-direction component Bx of the magnetic flux density at a position separated from the center of the surface in the width direction of the current line 21 by a predetermined distance h. 6B, the distance h from the center of the surface in the width direction of the current line 21 is 16.4 mm or more, the rise time of the x-direction component Bx of the magnetic flux density B is 0, that is, the current injected into the current line 21 is When the final value is reached, the x-direction component Bx of the magnetic flux density B is expected to reach 90% or more of the final value.

  According to the experimental results, when the center of the magnetic detection element 22 of the current sensor is disposed at a position of 17 mm or more from the center of the surface in the width direction of the current line 21, the current a injected into the current line 21 is 100 μsec and the final value is 30A. It was confirmed that the output voltage b of the current sensor reached 90% of the final value of the current sensor output, that is, the rise time of the current sensor became zero. It was also confirmed that the rise time of the current sensor becomes zero within the width direction of the current line 21 if the height from the surface of the current line 21 at the center of the magnetic detection element 22 of the current sensor is 17 mm or more.

  FIG. 7 shows three current lines having different widths and thicknesses, that is, a width W = 14 mm, a thickness t = 1.6 mm, a current line with a length of 200 mm, a width W = 20 mm, a thickness t = 5 mm, and a length. It is the figure which plotted the measured value and simulation value of hmin / W with respect to each width W of the current line of 200 mm, width W = 40 mm, thickness t = 2.5 mm, and length 200 mm. Here, hmin is the minimum distance between the center of the magnetic sensor 22 of the current sensor and the current line 21 such that the rise time of the current sensor is 0 for each current line, and hmin / W is each The current line is normalized by the width W of the current line 21. From this figure, hmin / W is set to 0.43 or more, that is, the center of the magnetic detection element 22 is in the width direction perpendicular to the current flow of the current line 21, and from the surface of the current line 21, the current line When the current injected from the power source to the current line reaches the final value, the output voltage from the current sensor is at least 90% of the final value. Thus, the effect that the substantial rise time can be reduced to zero can be obtained.

  The current sensor according to the present invention enables the output voltage from the current sensor to reach at least 90% of the final value when the current injected from the power source to the current line reaches the final value. This has the effect that the restriction on the position where the current sensor is arranged with respect to the line can be greatly relaxed, and is particularly useful as a current detection device for detecting current in vehicles, industrial equipment, and the like.

21 Current line 22 Magnetic detection element

Claims (1)

A current measuring device that includes a magnetic detection element that detects a magnetic field generated by a current flowing through a flat current line, and that measures the current based on the magnetic field detected by the magnetic detection element. The center is provided in a width direction perpendicular to the current flow of the current line and at a position separated from the current line surface by 0.43 W or more with respect to the width W of the current line. And current sensor.

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