Current detection device and circuit part of the device

Abstract

To provide a coreless current detector that can suppress influence of an external magnetic field and can maintain excellent frequency characteristics in high frequency regions as well.SOLUTION: The current detector includes: a current route 5 and a current route 6 divided by a slit 7; and a pair of magnetic detection elements 11 and 12 for respectively detecting a magnetic flux generated around the current route 5 and the current route 6 by a measurement target current. The current detector detects a measurement target current on the basis of detection signals obtained by the pair of magnetic detection elements 11 and 12. In that time, the current route 5 and the current route 6 are located asymmetrically to the axis L1 connecting the pair of magnetic detection elements 11 and 12.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a current detection device using a magnetic detection element. [Background technology]

[0002] Conventional current detection devices used in motor drive inverters and the like generally measure three-phase currents, and it is known that two or more magnetic detection elements are arranged to sandwich the current path to be measured, and the influence of nearby current paths and surrounding magnetic fields is canceled out by differentially calculating the detection signals, thereby accurately measuring the current to be measured.

[0003] For example, in Patent Document 1, a slit is drilled in a long, plate-shaped current path to be measured, and two current paths to be measured are divided symmetrically around the slit. The magnetic flux density generated by the two current paths to be measured is detected by a pair of magnetic detection elements arranged symmetrically in the plate thickness direction across the slit, and the detection signals are differentially calculated to cancel the influence of the surrounding magnetic field and accurately measure the magnitude of the current to be measured.

[0004] In addition, in Patent Document 2, a pair of magnetic detection elements is placed on both sides of at least one of multiple adjacent crank-shaped current paths, with each pair of magnetic detection elements positioned so that the magnetic flux density is equally applied to each magnetic detection element, and the detection signals obtained by each magnetic detection element are differentially calculated. Although there is influence from nearby current paths, the addition of the crank shape causes the pair of magnetic detection elements on the current path to be measured to detect the same magnetic flux density, so by performing differential calculation, the influence from nearby current paths is canceled out and the magnitude of the current to be measured is accurately measured. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent 6144597 [Patent Document 2] Patent 4839393 [Patent Document 3] Patent Publication No. 2005-283451 Figure 3 Summary of the Invention [Problem to be solved by the invention]

[0006] Figure 23 shows the configuration disclosed in Figure 2 of Patent Document 1. In a portion of a long, plate-shaped electric circuit 90 (extending in the Y direction) where a slit 93 is provided, the current flowing through the electric circuit 90 is divided into two by the slit 93, resulting in two current paths 91 and 92 that exist in the same direction. The lengths of the current paths 91 and 92 and the slit 93 in the width direction (X direction) are indicated by symbols a, b, and c, the plate thickness of the electric circuit (thickness direction is the Z direction) is indicated by symbol d, the distance in the Z direction between two magnetic detection elements 94 and 95 is indicated by symbol e, the line connecting the two magnetic detection elements 94 and 95 is indicated by axis L1, and the center line of the plate thickness of the electric circuit 90 is indicated by axis L2. The magnetic detection elements 94 and 95 are arranged symmetrically with respect to axis L2, and the electric circuit 90 is arranged so as to be symmetrical with respect to both axes L1 and L2. The two magnetic detection elements 94 and 95 have a sensitivity axis in the X direction, and when a current is passed through the current circuit 90 from the -Y direction to the +Y direction, they detect magnetic flux densities 98 and 99 in the X direction, which are opposite to each other, of magnetic flux lines 96 and 97 generated in the current paths 91 and 92, respectively.

[0007] FIG. 24 shows a simulation of magnetic flux distribution, extracted only in the X direction from the magnetic flux lines generated when a 100 A AC current is passed through the magnetic sensor with the dimensions a = 4 mm, b = 2 mm, c = 4 mm, d = 0.8 mm, and e = 2.5 mm shown in FIG. 23 . FIG. 24(a) shows the case where a 60 Hz AC current is passed through, and FIG. 24(b) shows the case where a 10 kHz AC current is passed through. As shown in FIG. 24(a), for 60 Hz, the magnetic flux density in the X direction detected by magnetic detection element 94 is 3.22 mT, and for magnetic detection element 95 it is −3.22 mT, resulting in a differential calculation of 6.44 mT. On the other hand, as shown in FIG. 24(b), for 10 kHz, the magnetic flux density in the X direction detected by magnetic detection element 94 is 2.90 mT, and for magnetic detection element 95 it is −2.90 mT, resulting in a differential calculation of 5.80 mT. When comparing 60 Hz and 10 kHz, there is a difference of approximately -10.0%, and it has previously been difficult to measure high frequencies accurately.

[0008] Furthermore, in the configuration of Patent Document 2, the crank-shaped electric circuits (conductors) are arranged side by side (the lined-up direction is the X direction), which increases the distance between each conductor in the X direction. In addition, in order to arrange the two magnetic detection elements arranged in the current path to be measured so that the magnetic flux density generated when current flows in the neighboring current path is equally applied, each conductor is arranged offset in its extension direction (Y direction). This increases the size in the XY plane, making it difficult to miniaturize the device in the past.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to miniaturize a current detection device that can accurately measure the magnetic flux generated by the current being measured up to high frequency bands, while suppressing the influence of nearby current paths and surrounding magnetic fields (influence of external magnetic fields). [Means for solving the problem]

[0010] The current detection device of the present invention comprises a flat electric circuit extending in the direction in which the current to be measured flows, with a through slit drilled perpendicular to the extension direction, and the current path being divided into two by the through slit, and a pair of magnetic detection elements which each detect the magnetic flux generated around the electric circuit by the current to be measured, wherein the divided current paths have an asymmetrical shape with respect to the axis connecting the pair of magnetic detection elements when viewed from a cross section perpendicular to the extension direction, and the current to be measured flowing in the electric circuit is divided by the through slit into the two divided current paths and flows in the same direction, and the pair of magnetic detection elements are each positioned so that their magnetic sensitive surfaces penetrate the magnetic field generated by the current flowing in the two divided current paths in opposite directions, and are also positioned within the projection plane of the through slit when viewed from a direction perpendicular to the extension direction of the electric circuit, and are equipped with a circuit section which performs differential calculations on the detection signals obtained from the pair of magnetic detection elements. [Effects of the Invention]

[0011] According to the present invention, by arranging two current paths asymmetrically with respect to the axis connecting the pair of magnetic detection elements, it is possible to provide a current detection device that suppresses the influence of external magnetic fields and has good frequency characteristics up to the high frequency range. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view of a current detection device according to a first embodiment of the present invention. [Figure 2] 1 is a circuit block diagram of a circuit section of a current detection device according to a first embodiment of the present invention. [Figure 3] FIG. 2 is a cross-sectional view of FIG. 1. [Figure 4] FIG. 4 is a diagram showing the magnetic flux distribution in FIG. [Figure 5] 4 is a table and a graph showing frequency characteristics of magnetic flux density in the current detection device according to the first embodiment of the present invention. [Figure 6] 4 is a table and a graph showing frequency characteristics of magnetic flux density in the current detection device according to the first embodiment of the present invention. [Figure 7] 4 is a table and a graph showing frequency characteristics of magnetic flux density in the current detection device according to the first embodiment of the present invention. [Figure 8] 4 is a table and a graph showing frequency characteristics of magnetic flux density in the current detection device according to the first embodiment of the present invention. [Figure 9] 4 is a table and a graph showing frequency characteristics of magnetic flux density in the current detection device according to the first embodiment of the present invention. [Figure 10] 1 is a cross-sectional view of a current detection device according to a first embodiment of the present invention. [Figure 11] 4 is a table and a graph showing frequency characteristics of magnetic flux density in the current detection device according to the first embodiment of the present invention. [Figure 12] FIG. 10 is a perspective view of a current detection device according to a second embodiment of the present invention. [Figure 13] FIG. 13 is a cross-sectional view of FIG. 12. [Figure 14] 10 is a table and a graph showing frequency characteristics of magnetic flux density in a current detection device according to a second embodiment of the present invention. [Figure 15] FIG. 10 is a perspective view of a current detection device according to a third embodiment of the present invention. [Figure 16] FIG. 16 is a cross-sectional view of FIG. 15. [Figure 17] 10 is a table and a graph showing frequency characteristics of magnetic flux density in a current detection device according to a third embodiment of the present invention. [Figure 18] FIG. 10 is a perspective view of a current detection device according to a fourth embodiment of the present invention. [Figure 19] FIG. 19 is a cross-sectional view of FIG. 18. [Figure 20] FIG. 20 is a magnetic flux distribution diagram in FIG. [Figure 21] FIG. 19 is a perspective view showing a modified version of the electrical path shown in FIG. 18. [Figure 22] FIG. 22 is a side view of FIG. 21. [Figure 23] FIG. 10 is a cross-sectional view showing an electric path and a circuit portion of a conventional example. [Figure 24] FIG. 10 is a magnetic flux distribution diagram in a conventional example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiment 1 Fig. 1(a) is a perspective view showing the appearance of a current detection device 100 according to a first embodiment of the present invention, and Fig. 1(b) is a diagram showing the relationship between current paths 5 and 6, a slit 7, and a circuit section 8 of an electric circuit 1. The X direction is the width direction of the electric circuit 1, the Z direction is the thickness direction of the electric circuit 1, and the Y direction is the direction in which the electric circuit 1 extends. Hereinafter, in the first embodiment, each direction will be defined similarly.

[0014] The current detection device 100 has a case 2 made of an insulating material (e.g., PPS: polyphenylene sulfide, PA: polyamide, PBT: polybutylene terephthalate, etc.) to which an electric circuit 1 made of, for example, copper or aluminum is fixed, and a printed circuit board 3 on which a circuit section 8, a connector section 4, and resistors and capacitors (not shown) are mounted by soldering is fixed with screws (not shown) or the like. A slit 7 is formed in the long plate-like electric circuit 1 extending in the Y direction, penetrating the electric circuit 1 from a direction (Z direction) perpendicular to the extension direction (Y direction), and the circuit section 8 is arranged along the slit 7 in a direction parallel to the Y direction and penetrating the electric circuit 1 in the Z direction.

[0015] At this time, in the portion of the electric circuit 1 where the slit 7 is provided, the current flowing through the electric circuit 1 is divided into two by the slit 7, resulting in the existence of two current paths 5 and 6 in the same direction. One end of the electric circuit 1 is connected to the output terminal of a semiconductor that drives a motor such as an IPM (intelligent power module), and the other end is connected to the input terminal of a motor, for example, and a motor drive current, which is the current to be measured, flows through the electric circuit 1.

[0016] Fig. 2 is a block diagram showing the circuit configuration of circuit unit 8 of current detection device 100 according to embodiment 1 of the present invention. In Fig. 2, circuit unit 8 includes a pair of magnetic detection elements 11 and 12, a first amplifier unit 13, a second amplifier unit 14, a differential calculation unit 15, power supply terminals 16 and 17, an output terminal 18, and a substrate 19. In current detection device 100, power of, for example, 5 V is supplied from the outside to power supply terminals 16 and 17 of circuit unit 8 via an interface such as connector unit 4 and printed circuit board 3, and an output signal of the differential calculation unit is output to the outside from output terminal 18.

[0017] The magnetic detection elements 11 and 12 are configured using, for example, a Hall element, an MR element, a GMR element, or a TMR element. An MR element is an element that detects magnetic flux using the magnetoresistive effect. A GMR element is an element that detects magnetic flux using the giant magnetoresistive effect. A TMR element is an element that detects magnetic flux using the tunnel magnetoresistive effect. In addition to these, any element can be used as the magnetic detection elements 11 and 12 as long as it can detect magnetic flux and output a detection signal according to the detection result.

[0018] The first amplifier 13 and the second amplifier 14 amplify the minute voltage signals output from the magnetic detection elements 11 and 12, respectively, and output the amplified signals to the differential calculation unit 15. The differential calculation unit 15 performs a differential calculation to find the difference between the voltage signals output from the first amplifier 13 and the second amplifier 14, respectively, and outputs the calculation result to an output terminal 18.

[0019] The substrate 19 is formed using, for example, a silicon substrate or a glass epoxy substrate, and secures the components of the circuit unit 8 in a predetermined arrangement and electrically connects the components to each other. The circuit unit 8, on which the components are mounted, is then molded with resin or the like, and can then be arranged and secured via the electric circuit 1 fixed to the case 2 and the printed circuit board 3, which is also fixed to the case 2 and on which the circuit unit 8 is mounted. In this case, the pair of magnetic detection elements 11 and 12 are each oriented with respect to the electric circuit 1 so that they are sensitive in opposing directions. These magnetic detection elements detect magnetic flux generated by the current to be measured flowing through the electric circuit 1 and output detection signals corresponding to the magnetic flux detection results to the first amplifier 13 and the second amplifier 14, respectively.

[0020] Figure 3 is a cross-sectional view of cross section 9, perpendicular to current paths 5 and 6 shown in Figure 1(b), as viewed from arrow 10. The lengths of current paths 5 and 6 and slit 7 in the X direction are designated by symbols a, b, and c. The thickness of electric circuit 1 is designated by symbol d. The distance in the Z direction between two magnetic detection elements 11 and 12 in circuit section 8 is designated by symbol e. The line connecting the two magnetic detection elements 11 and 12 is designated by axis L1. The center line of the thickness of electric circuit 1 is designated by axis L2. The magnetic detection elements 11 and 12 are arranged symmetrically with respect to axis L2. The electric circuit 1 is arranged symmetrically with respect to axis L2 but asymmetrically with respect to axis L1. For example, symbols a = 2 mm, b = 2 mm, c = 6 mm, d = 0.8 mm, and e = 2.5 mm. The two magnetic detection elements 11 and 12 have a sensitivity axis in the X direction, and when a current is passed through the current circuit 1 from the -Y direction to the +Y direction, they detect magnetic flux densities 22 and 23 in the X direction, which are opposite to each other in the magnetic flux lines 20 and 21 generated in the current paths 5 and 6, respectively.

[0021] Terminals 16, 17, and 18 of circuit section 8 protrude to one side, similar to the magnetic detection section of Patent Document 3 (FIG. 3 of JP-A-2005-283451), in the Z direction parallel to axis L1.

[0022] In the current detection device 100 configured in this manner, the magnetic flux densities in the X direction of magnetic flux lines 20 and 21 generated by the current to be measured, which is split into two by current paths 5 and 6 of the electrical circuit 1, are detected by magnetic detection elements 11 and 12 in the circuit unit 8, and the current to be measured is measured by finding the difference between the two. Here, we will confirm by simulation the high-frequency characteristics of the current to be measured when the current paths 5 and 6 are arranged asymmetrically with respect to the axis L1.

[0023] Figure 4 shows the magnetic flux distribution obtained by simulation, extracting only the X direction from the magnetic flux lines that are generated when an AC current of 100 A is applied, with the symbols a = 2 mm, b = 2 mm, c = 6 mm, d = 0.8 mm, and e = 2.5 mm shown in Figure 3. In addition, in Figures 24 and 4, symbol a is changed from 4 mm to 2 mm, and symbol c is changed from 4 mm to 6 mm, and current path 5 and current path 6 of current circuit 1 are arranged asymmetrically with respect to axis L1.

[0024] Figure 4(a) shows the results when a 60 Hz AC current is applied, and Figure 4(b) shows the results when a 10 kHz AC current is applied. As shown in Figure 4(a), at 60 Hz, the magnetic flux density in the X direction detected by magnetic detection element 11 is 3.06 mT, and that detected by magnetic detection element 12 is -3.07 mT, resulting in a differential calculation of 6.13 mT. On the other hand, as shown in Figure 4(b), at 10 kHz, the magnetic flux density in the X direction detected by magnetic detection element 11 is 3.15 mT, and that detected by magnetic detection element 12 is -3.14 mT, resulting in a differential calculation of 6.29 mT. Comparing 60 Hz and 10 kHz, there is only a difference of approximately 2.7%, and by arranging current paths 5 and 6 asymmetrically with respect to axis L1, accurate current measurement is possible up to high frequencies.

[0025] Here, the position of the slit 7 in the X direction is changed, and the high frequency characteristics of the current to be measured when the non-axially symmetrical arrangement state is changed are confirmed by simulation. 5A and 5B show a table (FIG. 5A) and a graph (FIG. 5B) of the frequency characteristics of the magnetic flux density obtained by detecting the magnetic flux density in the X direction using two magnetic detection elements 11 and 12 and performing differential calculations when a 100 A AC current (60 Hz to 100 kHz) is applied to the current detection device 100 according to the first embodiment of the present invention, with the symbols a+b+c shown in FIG. 3 fixed at 10 mm and symbol b fixed at 2 mm, and symbols a and c varied by 1 mm each. Also shown are a table (FIG. 5A) and a graph (FIG. 5B) of the frequency characteristics of the magnetic flux density fluctuation rate based on 60 Hz.

[0026] Here, for pattern A1, a = 4 mm, c = 4 mm, and the ratio of c to a is 1; for A2, a = 3 mm, c = 5 mm, and the ratio of c to a is 1.7; for A3, a = 2 mm, c = 6 mm, and the ratio of c to a is 3; and for A4, a = 1 mm, c = 7 mm, and the ratio of c to a is 7. Simulations were performed for eight AC frequencies: 60 Hz, 100 Hz, 300 Hz, 1 kHz, 3 kHz, 10 kHz, 30 kHz, and 100 kHz. Generally, motor drive inverters often have a switching frequency between 1 kHz and 20 kHz. At 10 kHz, as shown in Figure 5(b), the results are -10% for pattern A1, -7.0% for A2, 2.7% for A3, and 21.5% for A4. This indicates that patterns A2 and A3 can measure frequencies up to higher frequencies more accurately than pattern A1. Furthermore, pattern A4 has poorer accuracy in high frequencies than pattern A1.

[0027] From the above results, it can be seen that patterns A2 and A3 (the ratio of c to a is 1.7 to 3) in which current paths 5 and 6 are arranged non-axially symmetrically with respect to axis L1 shown in Figure 3 can provide more accurate measurements up to high frequencies than pattern A1 in which current paths 5 and 6 are arranged axially symmetrically with respect to axis L1.

[0028] Hereafter, in order to accommodate various electric circuits, the values ​​of the symbols a, b, c, d, and e are changed and the high-frequency characteristics of the current to be measured are confirmed by simulation. 6 shows a table (FIG. 6(a)) of the frequency characteristics of the magnetic flux density obtained when a 100 A AC current (60 Hz to 100 kHz) is applied to the current detection device 100 according to the first embodiment of the present invention. The table (FIG. 6(a)) shows the frequency characteristics of the magnetic flux density. The table (FIG. 6(b)) also shows a table and a graph (FIG. 6(b)) show the frequency characteristics of the magnetic flux density fluctuation rate relative to 60 Hz. The table (FIG. 6(b)) shows the frequency characteristics of the magnetic flux density fluctuation rate relative to 60 Hz.

[0029] Here, pattern B1 is a=4mm, c=4mm, B2 is a=3mm, c=5mm, B3 is a=2mm, c=6mm, and B4 is a=1mm, c=7mm, and the AC current frequencies were calculated by simulation at eight frequencies: 60Hz, 100Hz, 300Hz, 1kHz, 3kHz, 10kHz, 30kHz, and 100kHz.

[0030] As mentioned above, when comparing at 10 kHz, as shown in Figure 6(b), the results are -5.7% for pattern B1, -3.3% for B2, 4.6% for B3, and 20.4% for B4, which shows that patterns B2 and B3 can measure more accurately up to high frequencies than pattern B1. Also, pattern B4 has worse accuracy at high frequencies than pattern B1.

[0031] In this case, the detectable magnetic flux density is smaller compared to Figure 5, but patterns B2 and B3 (the ratio of c to a is 1.7 to 3), in which current paths 5 and 6 are arranged non-axially symmetrically with respect to axis L1 shown in Figure 3, can measure more accurately up to high frequencies than pattern B1, in which current paths 5 and 6 are arranged axially symmetrically with respect to axis L1.

[0032] 7 shows a table (FIG. 7(a)) of the frequency characteristics of the magnetic flux density obtained by detecting the magnetic flux density in the X direction when an AC current of 100 A (60 Hz to 100 kHz) is applied to the current detection device 100 according to the first embodiment of the present invention, and a table and graph (FIG. 7(b)) of the frequency characteristics of the magnetic flux density fluctuation rate with respect to 60 Hz are also shown. The table and graph (FIG. 7(b)) of the frequency characteristics of the magnetic flux density fluctuation rate with respect to 60 Hz are also shown.

[0033] Here, the pattern C1 is a=8mm, c=8mm, C2 is a=6mm, c=10mm, C3 is a=4mm, c=12mm, and C4 is a=2mm, c=14mm, and the AC frequency was calculated by simulation at eight frequencies: 60Hz, 100Hz, 300Hz, 1kHz, 3kHz, 10kHz, 30kHz, and 100kHz.

[0034] As mentioned above, when comparing at 10 kHz, as shown in Figure 7(b), the results are -10.1% for pattern C1, -7.8% for C2, 0.8% for C3, and 23.0% for C4, which shows that patterns C2 and C3 can measure more accurately up to high frequencies than pattern C1. Also, pattern C4 has worse accuracy at high frequencies than pattern C1.

[0035] Even in this case, the detectable magnetic flux density is smaller compared to Figure 5, but patterns C2 and C3 (the ratio of c to a is 1.7 to 3) in which current paths 5 and 6 are arranged non-axially symmetrically with respect to axis L1 shown in Figure 3 can measure more accurately up to high frequencies than pattern C1 in which current paths 5 and 6 are arranged axially symmetrically with respect to axis L1.

[0036] 8 shows a table (FIG. 8(a)) of the frequency characteristics of the magnetic flux density obtained by detecting the magnetic flux density in the X direction using two magnetic detection elements 11 and 12 and performing differential calculations. Similarly to FIGS. 6 and 7, FIG. 8 shows a table and a graph (FIG. 8(b)) of the frequency characteristics of the magnetic flux density fluctuation rate based on 60 Hz. The table and graph show the frequency characteristics of the magnetic flux density fluctuation rate based on 60 Hz. The table and graph show the frequency characteristics of the magnetic flux density fluctuation rate based on 60 Hz.

[0037] Here, the pattern D1 is a=4mm, c=4mm, D2 is a=3mm, c=5mm, D3 is a=2mm, c=6mm, and D4 is a=1mm, c=7mm, and the AC current frequencies were calculated by simulation at eight frequencies: 60Hz, 100Hz, 300Hz, 1kHz, 3kHz, 10kHz, 30kHz, and 100kHz.

[0038] As mentioned above, when comparing at 10 kHz, as shown in Figure 8(b), the results are -15.6% for pattern D1, -12.8% for D2, -1.7% for D3, and 23.2% for D4, which shows that patterns D2 and D3 can measure more accurately up to high frequencies than pattern D1. Also, pattern D4 has worse accuracy at high frequencies than pattern D1.

[0039] Even in this case, the detectable magnetic flux density is smaller compared to Figure 5, but a larger magnetic flux density can be detected than in Figures 6 and 7, so increasing the plate thickness d rather than widening the plate width will allow for heat generation countermeasures while ensuring magnetic flux. Also, patterns D2 and D3 (the ratio of c to a is 1.7 to 3), in which current paths 5 and 6 are arranged asymmetrically with respect to axis L1 as shown in Figure 3, allow for more accurate measurements up to high frequencies than pattern D1, in which current paths 5 and 6 are arranged line-symmetrically with respect to axis L1 as before.

[0040] 9 shows a table (FIG. 9(a)) of the frequency characteristics of the magnetic flux density obtained by differential calculation in the current detection device 100 according to the first embodiment of the present invention, and a table and graph (FIG. 9(b)) of the frequency characteristics of the magnetic flux density fluctuation rate with respect to 60 Hz as the reference frequency. The table shows ...

[0041] Here, the pattern E1 is a=4mm, c=4mm, E2 is a=3mm, c=5mm, E3 is a=2mm, c=6mm, and E4 is a=1mm, c=7mm, and the AC frequency was calculated by simulation at eight frequencies: 60Hz, 100Hz, 300Hz, 1kHz, 3kHz, 10kHz, 30kHz, and 100kHz.

[0042] As mentioned above, when comparing at 10 kHz, as shown in Figure 9(b), the results are -16.8% for pattern E1, -14.0% for E2, -2.5% for E3, and 25.4% for E4, which shows that patterns E2 and E3 can measure more accurately up to high frequencies than pattern E1. Also, pattern E4 has worse accuracy at high frequencies than pattern E1.

[0043] Even in this case, as in Figures 6 and 7, the detectable magnetic flux density is smaller than in Figure 5, but patterns E2 and E3 (the ratio of c to a is 1.7 to 3) in which current paths 5 and 6 are arranged asymmetrically with respect to axis L1 as shown in Figure 3 can measure more accurately up to high frequencies than pattern E1 in which current paths 5 and 6 are arranged symmetrically with respect to axis L1.

[0044] Here, a case will be confirmed in which the two magnetic detection elements 11 and 12 cannot be arranged symmetrically with respect to the axis L2 due to assembly errors, structural requirements, or the like. 10 is a cross-sectional view showing magnetic detection elements 24 and 25 at positions where two magnetic detection elements 11 and 12 have been displaced in the Z direction by an amount (symbol f) from that shown in FIG. 5 in the current detection device 100 according to the first embodiment of the present invention. Displaced by symbol f in the Z direction, the magnetic detection elements 24 and 25 are arranged asymmetrically with respect to axis L2, and detect magnetic flux densities in opposite directions, just like the magnetic detection elements 11 and 12 before displacement, but the magnitudes of the detected magnetic flux densities are different.

[0045] 11 shows a table (FIG. 11(a)) of the frequency characteristics of the magnetic flux density obtained by detecting the magnetic flux density in the X direction using magnetic detection elements 24 and 25, which are located at positions where two magnetic detection elements 11 and 12 are displaced in the Z direction by an amount f of 0.5 mm, when a 100 A AC current (60 Hz to 100 kHz) is passed through current detection device 100 according to embodiment 1 of the present invention, with symbols a+b+c shown in FIG. 10 fixed at 10 mm and symbol b fixed at 2 mm, and symbols a and c varied by 1 mm each. FIG. 11(b) shows a table and graph (FIG. 11(b)) of the frequency characteristics of the magnetic flux density fluctuation rate, based on 60 Hz.

[0046] Here, the pattern F1 is a=4mm, c=4mm, F2 is a=3mm, c=5mm, F3 is a=2mm, c=6mm, and F4 is a=1mm, c=7mm, and the AC current frequencies were calculated by simulation at eight frequencies: 60Hz, 100Hz, 300Hz, 1kHz, 3kHz, 10kHz, 30kHz, and 100kHz.

[0047] As mentioned above, when comparing at 10 kHz, as shown in Figure 11(b), the results are -9.7% for pattern F1, -6.8% for F2, 2.5% for F3, and 20.4% for F4, which shows that patterns F2 and F3 can measure more accurately up to high frequencies than pattern F1. Also, pattern F4 has worse accuracy at high frequencies than pattern F1.

[0048] In this case, as in Figures 6 to 9, the detectable magnetic flux density is smaller than in Figure 5, but patterns F2 and F3 (the ratio of c to a is 1.7 to 3) in which current paths 5 and 6 are arranged non-axially symmetrically with respect to axis L1 shown in Figure 10 can measure more accurately up to high frequencies than pattern F1 in which current paths 5 and 6 are arranged axially symmetrically with respect to axis L1.

[0049] As described above, the two current paths are arranged asymmetrically with respect to the axis L1, thereby improving the frequency characteristics when detecting magnetic flux in response to the current flowing through the current path. Therefore, by employing such an arrangement of magnetic detection elements and a current path structure in a current detection device, it is possible to provide a current detection device that has good frequency characteristics up to high frequencies while suppressing the effects of external magnetic fields.

[0050] Furthermore, the polarity of the fluctuation rate with a reference frequency of 60 Hz is reversed between patterns (A2 to F2) and (A3 to F3). In this case, the dimensions a and c were varied by 1 mm each, but by optimizing these dimensions, the fluctuation rate can be minimized.

[0051] Embodiment 2 FIG. 12(a) is a perspective view showing the appearance of a current detection device 101 according to a second embodiment of the present invention, and FIG. 12(b) is a diagram showing the relationship between current paths 30 and 31, slit 32, and circuit unit 81 of electric circuit 26. The X direction is the width direction of electric circuit 26, the Y direction is the upward direction from the bottom of the page, and the Z direction is the direction perpendicular to a plane parallel to the X and Y directions. Hereinafter, each direction will be defined similarly in the second embodiment. Current detection device 101 includes a case 27 made of an insulating material (e.g., PPS: polyphenylene sulfide, PA: polyamide, PBT: polybutylene terephthalate, etc.) to which electric circuit 26 made of, for example, copper or aluminum is fixed. A printed circuit board 28 on which circuit unit 81, connector unit 29, resistors, capacitors (not shown), etc. are mounted by soldering is fixed by screws (not shown) or the like.

[0052] The long plate-shaped electrical circuit 26 extending in the Y direction is bent at 90 degrees along the bending line 33, and a slit 32 is drilled at the bent portion, with a circuit portion 81 arranged in the slit 32 in a direction parallel to the Y direction.

[0053] At this time, in the portion of the electric circuit 26 where the slit 32 is provided, the current flowing through the electric circuit 26 is divided into two by the slit 32, resulting in two current paths 30, 31 existing in the same direction. The two current paths 30, 31 are designated 30a, 31a before bending, and 30b, 31b after bending. The circuit unit 81 has the same internal configuration as the circuit unit 8 described in the first embodiment, but the protruding direction of the terminals 16, 17, 18 is different. The protruding direction is the Y direction, which is perpendicular to the axis L1 shown in FIG. 13.

[0054] 12(b), viewed from the direction of arrow 35. The lengths of current paths 30a, 31a, and slit 32 in the X direction are designated by symbols a, b, and c, the thickness of electric circuit 26 is designated by symbol d, the distance in the Z direction between two magnetic detection elements 11 and 12 in circuit unit 81 is designated by symbol e, the line connecting the two magnetic detection elements 11 and 12 is designated by axis L1, and the center line of the thickness of electric circuit 26 is designated by axis L2. Magnetic detection elements 11 and 12 are arranged symmetrically with respect to axis L2, and current paths 30a and 31a are arranged symmetrically with respect to axis L2 but asymmetrically with respect to axis L1.

[0055] For example, the symbols a = 2 mm, b = 2 mm, c = 6 mm, d = 0.8 mm, and e = 2.5 mm. The two magnetic detection elements 11 and 12 have a sensitivity axis in the X direction, and when a current is passed through the current circuit 26 from the -Y direction to the -Z direction, they detect magnetic flux densities 38 and 39 in the X direction, which are opposite to each other, of magnetic flux lines 36 a and 37 a generated in current paths 30 a and 31 a, respectively, and magnetic flux lines 36 b and 37 b generated in current paths 30 b and 31 b, respectively.

[0056] 14 shows a table (FIG. 14(a)) of the frequency characteristics of the magnetic flux density obtained by detecting the magnetic flux density in the X direction using two magnetic detection elements 11 and 12 and performing differential calculations when a current of 100 A (60 Hz to 100 kHz) is applied to the current detection device 101 according to the second embodiment of the present invention, with symbols a+b+c shown in FIG. 13 fixed at 10 mm and symbol b fixed at 2 mm, symbols a and c varied by 1 mm each. FIG. 14(b) also shows a table and graph (FIG. 14(b)) of the frequency characteristics of the magnetic flux density fluctuation rate based on 60 Hz.

[0057] Here, the dimensions of pattern G1 are a = 4 mm, c = 4 mm, G2 are a = 3 mm, c = 5 mm, G3 are a = 2 mm, c = 6 mm, and G4 are a = 1 mm, c = 7 mm. The AC frequencies were calculated by simulation at eight frequencies: 60 Hz, 100 Hz, 300 Hz, 1 kHz, 3 kHz, 10 kHz, 30 kHz, and 100 kHz. As shown in Figure 14(b), when compared at 10 kHz, the results are -8.1% for pattern G1, -5.5% for G2, 3.4% for G3, and 20.5% for G4. This indicates that patterns G2 and G3 provide better measurement accuracy up to higher frequencies than pattern G1. Furthermore, pattern G4 exhibits worse accuracy at higher frequencies than pattern G1.

[0058] From the above results, it can be seen that patterns G2 and G3 (the ratio of c to a is 1.7 to 3), in which current paths 30 and 31 are arranged non-axially symmetrically with respect to axis L1, can provide more accurate measurements up to high frequencies than pattern G1, in which current paths 30 and 31 are arranged axially symmetrically with respect to axis L1.

[0059] Furthermore, compared to FIG. 5, where the conditions of symbols a, b, c, d, and e are the same, the detected magnetic flux density can be increased by bending the electric path. In the second embodiment, only the state in which the electric trace 26 is bent at 90 degrees in the −Z direction has been described, but the same effect can be obtained even when the end of the electric trace 26 is bent at 90 degrees in the +Z direction.

[0060] As explained above, even in the case of the electric circuit bent at 90 degrees, the two current paths are arranged asymmetrically with respect to the axis L1, thereby improving the frequency characteristics when detecting magnetic flux in response to the current flowing in the electric circuit. Therefore, by employing such an arrangement of magnetic detection elements and an electric circuit structure in a current detection device, it is possible to provide a current detection device that has good frequency characteristics up to high frequencies while suppressing the influence of external magnetic fields. Furthermore, the terminals 16, 17, and 18 of the circuit section 81 protrude in the Y direction, and can be easily soldered to the printed circuit board 28 that is positioned parallel to the XZ plane.

[0061] Embodiment 3 FIG. 15(a) is a perspective view showing the appearance of a current detection device 102 according to a third embodiment of the present invention, and FIG. 15(b) is a diagram showing the relationship between current paths 44, 45, and 46 of an electric circuit 40, a slit 47, and a circuit unit 81. The X direction is the width direction of the electric circuit 40, the Y direction is the direction from bottom to top of the page, and the Z direction is the direction perpendicular to a plane parallel to the X and Y directions. Hereinafter, each direction will be defined similarly in the third embodiment. The current detection device 102 includes a case 41 made of an insulating material (e.g., PPS: polyphenylene sulfide, PA: polyamide, PBT: polybutylene terephthalate, etc.) to which an electric circuit 40 made of, for example, copper or aluminum is fixed. A printed circuit board 42 on which a circuit unit 81, a connector unit 43, resistors, capacitors (not shown), etc. are mounted by soldering is fixed by screws (not shown) or the like.

[0062] The long plate-like electric circuit 40 extending in the Y direction is bent at 90 degrees along bending line 48 (first bend) and then bent again at 90 degrees along bending line 49 (second bend) to form the U-shape. A slit 47 is formed in the first bend bent at bending line 48, and a circuit section 81 is disposed in the slit 47 in a direction parallel to the Y direction. At this time, in the portion of electric circuit 40 where slit 47 is formed, the current flowing through electric circuit 40 is divided into two by slit 47, and thus two current paths 44 and 45 exist in the same direction.

[0063] The two current paths 44, 45 are designated as 44a and 45a before being bent at bending line 48, 44b and 45b after being bent (at a first bend), and a further current path 46 after the two current paths 44, 45 join and are bent at bending line 49 (at a second bend). Circuit unit 81 has the same internal configuration as circuit unit 8 described in the first embodiment, but differs in the protruding directions of terminals 16, 17, and 18. The protruding direction is the Y direction, which is perpendicular to axis L1 shown in FIG.

[0064] 16 is a cross-sectional view of cross section 50 perpendicular to current paths 44a and 45a shown in FIG. 15(b), as viewed from arrow 51. The lengths of current paths 44a, 45a, and slit 47 in the X direction are designated by symbols a, b, and c, the thickness of electric circuit 40 is designated by symbol d, the distance in the Z direction between two magnetic detection elements 11 and 12 in circuit section 81 is designated by symbol e, the line connecting the two magnetic detection elements 11 and 12 is designated by axis L1, and the center line of the thickness of electric circuit 40 is designated by axis L2. Magnetic detection elements 11 and 12 are arranged symmetrically with respect to axis L2, and current paths 44a and 45a are arranged symmetrically with respect to axis L2 but asymmetrically with respect to axis L1.

[0065] For example, the symbols a = 2 mm, b = 2 mm, c = 6 mm, d = 0.8 mm, and e = 2.5 mm. The sensitivity axis of the two magnetic detection elements 11 and 12 is in the X direction, and when a current is passed through the current circuit 40 from the arrow 51 to the current path 46, the two magnetic detection elements 11 and 12 detect magnetic flux densities 55 and 56 in the X direction, which are opposite to each other, of magnetic flux lines 52a and 53a generated in the current paths 44a and 45a, magnetic flux lines 52b and 53b generated in the current paths 44b and 45b, and magnetic flux line 54 generated in the current path 46.

[0066] 17 shows a table (FIG. 17(a)) of the frequency characteristics of the magnetic flux density obtained by detecting the magnetic flux density in the X direction using two magnetic detection elements 11 and 12 and performing differential calculations when a 100 A AC current (60 Hz to 100 kHz) is applied to an electric circuit 40 in a current detection device 102 according to embodiment 3 of the present invention, with symbols a+b+c shown in FIG. 16 fixed at 10 mm and symbol b fixed at 2 mm, and symbols a and c varied by 1 mm each. FIG. 17(b) also shows a table and graph (FIG. 17(b)) of the frequency characteristics of the magnetic flux density fluctuation rate based on 60 Hz.

[0067] Here, for pattern H1, a = 4 mm, c = 4 mm, for H2, a = 3 mm, c = 5 mm, for H3, a = 2 mm, c = 6 mm, and for H4, a = 1 mm, c = 7 mm. Simulations were performed at eight AC frequencies: 60 Hz, 100 Hz, 300 Hz, 1 kHz, 3 kHz, 10 kHz, 30 kHz, and 100 kHz. As shown in Figure 17(b), when compared at 10 kHz, the results were -5.1% for pattern H1, -3.0% for H2, 4.0% for H3, and 18.3% for H4. This indicates that patterns H2 and H3 provide better measurement accuracy up to higher frequencies than pattern H1. Furthermore, pattern H4 exhibits worse accuracy at higher frequencies than pattern H1.

[0068] From the above results, it can be seen that patterns H2 and H3 (the ratio of c to a is 1.7 to 3) in which the current paths 44 and 45 are arranged non-symmetrically with respect to the axis L1 can measure with higher accuracy up to high frequencies than pattern H1 in which the current paths 44 and 45 are arranged symmetrically with respect to the axis L1.

[0069] Furthermore, compared with FIG. 5, which has the same conditions for the symbols a, b, c, d, and e as in the second embodiment, the detected magnetic flux density can be further increased by further bending the electric path.

[0070] In the third embodiment, slits 47 are provided only in the first bent portion, but not in the second bent portion. If slits 47 similar to those in the first bent portion were provided in the second bent portion, magnetic flux lines 54 generated from current path 46 would be applied to magnetic detection element 12 with a magnetic flux density that is a composite of the X and Z directions, just like magnetic flux lines 52a and 53a generated from current paths 44a and 45a. As a result, magnetic detection element 12, which detects only the magnetic flux density in the X direction, would detect a lower magnetic flux density. By not providing slits 47 in the second bent portion, magnetic flux lines 54 generated from current path 46 would be approximately parallel to the X direction in magnetic detection element 12, allowing greater magnetic flux density to be detected.

[0071] In the third embodiment, only the state in which the electrical circuit 40 is bent at 90 degrees in the -Z direction along the bending line 48, and then further bent at 90 degrees in the -Y direction along the bending line 49 to form the U-shape has been described; however, the same effect can be achieved even if the electrical circuit 40 is bent at 90 degrees in the Z direction along the bending line 48, and then further bent at 90 degrees in the -Y direction to form the U-shape.

[0072] As described above, even in an electric circuit that is bent 90 degrees and then bent again 90 degrees to form a U-shape, the two current paths are arranged asymmetrically with respect to the axis L1, thereby improving the frequency characteristics when detecting magnetic flux in response to the current flowing in the electric circuit. Therefore, by employing such an arrangement of magnetic detection elements and an electric circuit structure in a current detection device, it is possible to provide a current detection device that has good frequency characteristics up to high frequencies while suppressing the effects of external magnetic fields. Furthermore, the terminals 16, 17, and 18 of the circuit section 81 protrude in the Y direction, and can be easily soldered to the printed circuit board 42 that is positioned parallel to the XZ plane.

[0073] Embodiment 4 18(a) is a perspective view showing the appearance of a current detection device 103 according to a fourth embodiment of the present invention, and FIG. 18(b) is a diagram showing the relationship between three lined-up electric traces 57, each slit 61, and each circuit portion 81. The X direction is the width direction of the electric traces 57, the Y direction is the direction from bottom to top on the page, and the Z direction is the direction perpendicular to a plane parallel to the X and Y directions. Hereinafter, in the fourth embodiment, each direction will be defined similarly.

[0074] The current detection device 103 is made of, for example, copper or aluminum, and is bent into a U-shape in the thickness direction. Slits 61 are drilled at the bent portions. Three electric circuits 57 (electric circuits 57U, 57V, 57W in order from the -X direction) similar to those of the third embodiment are fixed in the X direction. The case 58 is made of an insulating material (for example, PPS: polyphenylene sulfide, PA: polyamide, PBT: polybutylene terephthalate, etc.). Circuit sections 81U, 81V, 81W and connector sections 60, resistors, capacitors (not shown), etc. are arranged in the slits 61U, 61V, 61W drilled in each electric circuit 57, and a printed circuit board 59 is mounted by soldering. The printed circuit board 59 is fixed by screws (not shown) or the like.

[0075] Each electric circuit 57 and each circuit unit 81 has the same configuration as that described in embodiment 3, and therefore description thereof will be omitted. The currents flowing through electric circuits 57U, 57V, and 57W are defined as U-phase current, V-phase current, and W-phase current. By providing electric circuits 57U, 57V, and 57W that are processed into a U-shape and have slits 61U, 61V, and 61W drilled in the bent portions, and three circuit units 81U, 81V, and 81W, current detection device 103 can detect three-phase currents.

[0076] 18(a) and 18(b), in the current detection device 103, circuit units 81U, 81V, and 81W and electric circuits 57U, 57V, and 57W of adjacent phases aligned in the X direction are arranged so as to be shifted in the Z direction. This point will be described with reference to FIGS. 19 and 20.

[0077] 18(b), a cross section 62 parallel to the ZX plane is shown in the direction of arrow 63. In the portion of electric circuit 57U where slit 61U is provided, the U-phase current flowing through electric circuit 57U is split into two by slit 61U, and thus exists as two current paths 64 and 65 flowing in the same direction.

[0078] The paths parallel to the Y axis of the two current paths 64, 65 are current paths 64a, 65a, the paths parallel to the Z direction are current paths 64b, 65b, and the path where the two current paths 64, 65 merge, is parallel to the Y direction, and a U-phase current flows in the opposite direction to the current paths 64a, 65a is current path 66.

[0079] Two magnetic detection elements 11V and 12V mounted on a circuit section 81V arranged in a slit 61V of an electric circuit 57V detect magnetic flux densities 70 and 71 in opposite directions, that is, in the X direction, when a current is passed through the electric circuit 57V, as described in the third embodiment.

[0080] The center line of the thickness of current paths 64a and 65a of electric circuit 57U is axis L3, the center line of the thickness of current path 66 of electric circuit 57U is axis L4, and the center line of axes L3 and L4 in the Z direction is center line L5. In this case, magnetic detection elements 11V and 12V arranged in slit 61V of adjacent phase 57V are arranged so as to be approximately symmetrical with respect to center line L5. Here, the relationship between electric circuit 57U and magnetic detection elements 11V and 12V mounted on circuit unit 81V is shown, but electric circuit 57V and circuit units 81U and 81W, and electric circuit 57W and circuit unit 81V are also arranged so as to have a similar positional relationship.

[0081] When a U-phase current is applied to current path 66 of electric circuit 57U from the -Y direction, magnetic flux generated from electric circuit 57U becomes magnetic flux lines 67a and 67b generated from current paths 64a and 65a, magnetic flux lines 68a and 68b generated from current paths 64b and 65b, and magnetic flux line 69 generated from current path 66. The magnetic flux line formed by combining magnetic flux lines 67a and 67b is magnetic flux line 67, and the magnetic flux line formed by combining magnetic flux lines 68a and 68b is magnetic flux line 68.

[0082] The influence of magnetic flux lines 67, 68, and 69 on magnetic detection elements 11V and 12V arranged on electric current path 57V, which is adjacent to electric current path 57U in the X direction and is the adjacent phase, will now be described. First, the influence of the magnetic flux lines 68 on the magnetic detection elements 11V and 12V will be described. Due to the influence of magnetic flux lines 68, magnetic detection element 11V detects magnetic flux density in the X direction, and similarly, magnetic detection element 12V detects magnetic flux density in the X direction. At this time, magnetic detection elements 11V and 12V are disposed at approximately equal positions in the X and Y directions when viewed from current paths 64b and 65b. Therefore, magnetic flux 68 generated from current paths 64b and 65b extending in the Z direction causes magnetic detection elements 11V and 12V to detect equivalent magnetic flux densities in the same direction. Therefore, the influence of magnetic flux lines 68 can be canceled out by performing a differential calculation.

[0083] Next, we will explain the effect of magnetic flux lines 67 and 69 on magnetic detection elements 11V and 12V. Due to the effect of magnetic flux line 67, magnetic detection element 11V detects magnetic flux density in the X direction, and similarly, magnetic detection element 12V detects magnetic flux density in the X direction. At this time, magnetic detection elements 11V and 12V differ in the distance in the Z direction from axis L3, which is the center line of the plate thickness of current paths 64a and 65a, and therefore the magnetic flux density detected by magnetic detection element 12V, which is closer to axis L3, is greater than that detected by magnetic detection element 11V. Therefore, when a differential calculation is performed, the effect is limited by the difference in magnetic flux density.

[0084] However, due to the influence of magnetic flux line 69 generated from current path 66, the magnetic flux density detected by magnetic detection element 11V, which is closer to axis L4, is greater than that detected by magnetic detection element 12V, contrary to the influence of magnetic flux line 67. Here, center line L5 is the center line of axes L3 and L4 in the Z direction, and magnetic detection elements 11V and 12V are arranged approximately symmetrically with respect to center line L5. Therefore, the influences of magnetic flux line 67 and magnetic flux line 69 are combined in magnetic detection elements 11V and 12V, resulting in approximately the same magnetic flux density. Therefore, the influences of magnetic flux lines 67 and 69 can be canceled out by performing a differential calculation.

[0085] FIG. 20 shows a magnetic flux distribution obtained by extracting only the X direction from magnetic flux lines generated when a direct current of 100 A is applied to the electric circuit 57U by simulation. When current is passed through electric circuit 57U, the magnetic flux density in the direction received by magnetic detection element 11V, which is located on electric circuit 57V, the adjacent phase and adjacent to electric circuit 57U in the X direction, is 0.83 mT, and the magnetic flux density in the X direction received by magnetic detection element 12V is 0.83 mT, and it can be seen that by performing a differential calculation, there is no longer any influence from electric circuit 57U, the adjacent phase. Similar results are obtained for the electric circuits and magnetic detection elements of the other adjacent phases.

[0086] Although the U-shaped configuration has been described here, the same effect can be obtained when the ends of the electrical path are bent by 90 degrees in the -Z direction and +Z direction.

[0087] As explained above, by arranging multiple U-shaped current paths in a staggered manner in the thickness direction, it is possible to eliminate the influence of adjacent phases. Furthermore, because it is possible to eliminate the influence of adjacent phases, the distance between adjacent phases can be shortened, and the current detection device can be made smaller.

[0088] Therefore, by employing such an arrangement of magnetic detection elements and a current path structure in a current detection device, it is possible to provide a small current detection device with good frequency characteristics up to high frequency ranges while suppressing the influence of external magnetic fields.

[0089] Fig. 21 is a perspective view showing electric traces 72 (72U, 72V) and circuit sections 81 (81U, 81V) which are modifications of electric traces 57 (57U, 57V) in Fig. 18(b). Fig. 22 is a side view of the periphery of electric trace 72V in Fig. 21 as seen from the X direction.

[0090] 21 , electric circuit 72V extends in the −Z direction, is bent 90 degrees in the Y direction along bend line 73 (third bend), then is bent 90 degrees in the −Z direction along bend line 74 (first bend), and is formed into a convex shape consisting of a first clamp bend, and is further bent 90 degrees in the −Y direction along bend line 75 (second bend), and then is bent 90 degrees in the −Z direction along bend line 76 (fourth bend). A slit 77V is formed in the first bend formed by bend line 74, and circuit section 81V is disposed in slit 77V in a direction parallel to the Y direction. At this time, in the portion where slit 77V is formed, the current flowing through electric circuit 72V is split into two by slit 77V, resulting in two current paths 78V and 79V flowing in the same direction.

[0091] In addition, the two current paths 78V and 79V are bent at the first bend (bending at bend line 92) as in the circuit 40, then merge and are bent at the second bend (bending at bend line 75) to form a current path of 80V. The circuit unit 81V has the same internal configuration as the circuit unit 8 described in the first embodiment, but differs in the direction in which the terminals 16, 17, and 18 protrude. The direction in which the terminals protrude is the Y direction, which is perpendicular to the axis L1 shown in FIG. 16. The V-phase electric circuit 72V has been described above as a representative example, but the same applies to the U-phase electric circuit 72U. Note that the W-phase electric circuit is not shown in FIG. 21, but the same applies when a W-phase electric circuit is present.

[0092] In the electric circuit 72, the relationship between the current paths 78 and 79 and the circuit unit 81 is similar to the relationship between the current paths 44 and 45 and the circuit unit 81 of the electric circuit 40 of the third embodiment shown in Fig. 16. Therefore, by arranging the two current paths asymmetrically with respect to the axis L1 in Fig. 16, it is possible to improve the frequency characteristics when detecting magnetic flux in response to the current flowing through the electric circuit. Therefore, by employing such an arrangement of magnetic detection elements and an electric circuit structure in a current detection device, it is possible to provide a current detection device that has good frequency characteristics up to high frequencies while suppressing the influence of external magnetic fields.

[0093] Furthermore, the protruding direction of terminals 16, 17, and 18 of circuit section 81 is the Y direction, and they can be easily soldered to printed circuit board 59, which is positioned parallel to the XZ plane formed by the width direction (X direction) of electrical path 72 and the extension direction (Z direction) of electrical path 72. Furthermore, even if the position of the axis L3 and the axis L4 shown in FIG. 19 changes due to a change in the shape of the electrical circuit 72 and the position of the circuit part 81 in the Z direction changes, this can be accommodated by changing the soldering position of the circuit part 81 to the printed circuit board 59.

[0094] In the case of a convex-shaped electrical circuit such as electrical circuit 72 shown in Figure 22, unlike a flat electrical circuit such as that shown in Figure 1, the electrical circuit has a thickness f1 in the thickness direction (Y direction) of the plate, which raises the concern that the thickness of the current detection device in the Y direction will become thicker.

[0095] When circuit unit 81 is used, terminals 16, 17, and 18 of circuit unit 81 are aligned in the Z direction with their protruding direction in the Y direction, so that the Y-direction dimension f2 of the molded package of circuit unit 81 is not affected by the number or size of the terminals, and it is sufficient to ensure the dimension (e.g., 3.5 mm) necessary for arranging magnetic detection elements 11 and 12; and the Y-direction dimension f1 of electrical circuit 72 is also not affected by terminals 16, 17, and 18 of circuit unit 81, and it is sufficient to ensure the dimension (e.g., 5 mm) necessary for arranging the magnetic detection elements 11 and 12 surrounding them.

[0096] On the other hand, when using a conventional circuit unit 8, terminals 16, 17, and 18 protrude in the Z direction, so the Y-direction dimension of circuit unit 8 and electrical path 72 is greatly affected by the number and size of the terminals. The printed circuit board to which terminals 16, 17, and 18 protruding in the Z direction in circuit diagram 8 are soldered is positioned parallel to the XY plane, and reducing the dimension in the Y direction makes it difficult to ensure sufficient component mounting area.

[0097] As described above, by using circuit section 81 in which terminals 16, 17, and 18 protrude in the Y direction, a current detector having a small thickness in the Y direction can be obtained. Although the slit 77 of the electric path 72 is provided only in the first bent portion, it may be provided so as to extend from the first bent portion to the third bent portion. In addition, the slit 77 of the electrical circuit 72 may be provided only in the third bend, in which case the terminals 16, 17, and 18 of the circuit portion 81 may be protruded in the -Y direction, and the printed circuit board 59 may be positioned close to the electrical circuit 72 in the -Y direction.

[0098] As described above, by combining the convexly bent electrical circuit with a slit drilled in at least one of the bent portions with a circuit section having terminals drawn out perpendicular to the line connecting the two magnetic detection elements arranged within the circuit section, a thin current detection device can be provided.

[0099] Therefore, by combining what has been described so far, and adopting such an arrangement of magnetic detection elements, a circuit section having terminal sections, and an electrical path structure in a current detection device, it is possible to provide a current detection device that is small in size and has good frequency characteristics up to the high frequency range while suppressing the effects of external magnetic fields. [Explanation of symbols]

[0100] 1:Electric circuit 2: Case part 3: Printed circuit board 4: Connector part 5: Current path 6: Current path 7: Slit 8:Circuit section 9: Cross section 10: Arrow 11: Magnetic detection element 12: Magnetic detection element 13: First amplifier 14: Second amplifier 15: Differential calculation section 16: Power terminal 17: Power terminal 18: Output terminal 19: Base material 20: Magnetic flux lines 21: Magnetic flux lines 22: Magnetic flux density in the X direction 23: Magnetic flux density in the X direction 24: Magnetic detection element 25: Magnetic detection element 26:Electric circuit 27: Case part 28: Printed circuit board 29: Connector part 30: Current path 31: Current path 32: Slit 33: Folding line 34: Cross section 35: Arrow 36: Magnetic flux lines 37: Magnetic flux lines 38: Magnetic flux density in the X direction 39: Magnetic flux density in the X direction 40:Electric circuit 41: Case part 42: Printed circuit board 43: Connector part 44: Current path 45: Current path 46: Current path 47: Slit 48: Folding line 49: Folding line 50: Cross section 51: Arrow 52: Magnetic flux lines 53: Magnetic flux lines 54: Magnetic flux lines 55: Magnetic flux density in the X direction 56: Magnetic flux density in the X direction 57:Electric circuit 58: Case part 59: Printed circuit board 60: Connector part 61: Slit 62: Cross section 63: Arrow 64: Current path 65: Current path 66: Current path 67: Magnetic flux lines 68: Magnetic flux lines 69: Magnetic flux lines 70: Magnetic flux density in the X direction 71: Magnetic flux density in the X direction 72:Electric circuit 73: Folding line 74: Folding line 75: Folding line 76: Folding line 77: Slit 78: Current path 79: Current path 80: Current path 81:Circuit section 90:Electric circuit 91: Current path 92: Current path 93: Slit 94: Magnetic detection element 95: Magnetic detection element 96: Magnetic flux lines 97: Magnetic flux lines 98: Magnetic flux density in the X direction 99: Magnetic flux density in the X direction 100: Current detection device 101: Current detection device 102: Current detection device 103: Current detection device

Claims

1. A flat electric circuit extending in the direction in which the current to be measured flows, with a through slit drilled in a direction perpendicular to the extending direction, and divided into a current path 1 and a current path 2 by the through slit; a pair of magnetic detection elements each detecting a magnetic flux generated around the electric circuit by the current to be measured; the current path 1 and the current path 2 have shapes that are asymmetrical with respect to an axis connecting the pair of magnetic detection elements when viewed from a cross section perpendicular to the extension direction; The current to be measured flowing through the electric circuit is divided into current path 1 and current path 2 by the through slit and flows in the same direction, the pair of magnetic detection elements are arranged to penetrate a magnetic field generated by the currents branched into the current path 1 and the current path 2, have a sensitivity axis in the width direction of the electric path, are arranged within a through slit projection plane when viewed from a direction perpendicular to the extension direction of the electric path, and include a circuit unit that performs differential calculation of detection signals obtained from the pair of magnetic detection elements, A current detection device characterized in that the path width ratio between the current path 1 and the current path 2 is 1.7 or more and 3 or less.

2. 2. The current detection device according to claim 1, wherein the thickness of the flat electric circuit is smaller than the distance between the pair of magnetic detection elements.

3. 3. The current detection device according to claim 1, wherein the center between the pair of magnetic detection elements is substantially aligned with a line that bisects the thickness of the flat electric circuit.

4. 4. The current detection device according to claim 1, wherein the electric path has a first bent portion bent at a portion where the through slit is present.

5. A current detection device as described in any one of claims 1 to 4, characterized in that the electric circuit has a first bent portion bent at the part where the through slit is present and a second bent portion bent at the part where the through slit is not present.

6. The electric circuit has two or more a central position between the pair of magnetic detection elements of one of the electric paths substantially coincides with a central position between the first bent portion and the second bent portion of another adjacent electric path; a center position between the first bent portion and the second bent portion of one of the electric paths substantially coincides with a center position between the pair of magnetic detection elements of another adjacent electric path; The current detection device according to claim 5 .

7. 7. The current detection device according to claim 1, wherein the magnetic detection element is a Hall element, an MR element, a GMR element, or a TMR element.

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