Current sensor

Abstract

To provide a highly sensitive, small-type current sensor which does not cause deterioration of sensitivity even in a high frequency region and is less likely to be affected by a magnetic flux generated by a current flowing in an adjacent phase conductor.SOLUTION: Three or more sets of a conductor 20 which extends in an X-axis direction and partially has a first detection unit extending in a +Y-axis direction and a second detection unit extending in a -Y-axis direction, and a circuit portion 10 which is close to the conductor 20 and incorporates a pair of magnetic detection elements are arranged in a Z-axis direction. The pair of magnetic detection elements are arranged at a position sandwiching one of the first detection unit and the second detection unit, in which a current to be measured flows, from the X-axis direction. Center positions of the pair of magnetic detection elements substantially coincide with center positions of the first detection unit and the second detection unit of the adjacent conductor 20 in the X-axis direction. Shortest distances between the centers of the pair of magnetic detection elements and the center of a Y-axis and Z-axis cross section of the adjacent conductor 20 are substantially the same.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] In order to accommodate the high-speed switching of inverters, current sensors used in inverters necessary for controlling three-phase motors mounted on recent hybrid and electric vehicles are required to have current measurement frequency characteristics that extend well into the high frequency range, i.e., sensitivity does not decrease even in the high frequency range of the current to be measured and detected, and they are required to be small, lightweight, and low-cost. To meet this demand, a current sensor is known that achieves small size and weight reduction by eliminating a core that collects magnetic flux generated by the current to be measured and detected (hereinafter referred to as coreless), and that has a current measurement frequency characteristic that extends well into the high frequency range by arranging a pair of magnetic detection elements so that the distances from the center in the longitudinal direction of the rectangular cross section of the conductor through which the current to be measured and detected flow are asymmetric (for example, see Figs. 4A and 4B of Patent Document 1).

[0003] In addition, a current sensor is known that cancels the influence of external magnetic flux from adjacent conductors by arranging multiple adjacent conductors, each of which has a U-shape in part, in which the current flows in opposite directions at 90 degrees (-Y-axis direction) and 270 degrees (+Y-axis direction) relative to the extension direction of the conductor (+X-axis direction), and each of which has a pair of magnetic detection elements arranged to detect the Y-axis direction current of the U-shape, and aligning the center of the U-shape of the adjacent conductor with the center of its own pair of magnetic detection elements (for example, see Figure 14B of Patent Document 1).

[0004] Furthermore, since a coreless current sensor does not have a core to collect the magnetic flux generated by the current to be measured, the magnetic flux density received by the magnetic detection element (magnetic sensor) is small, resulting in low sensitivity to the measurement detection current. To address this decrease in sensitivity to the measurement current, a current sensor is known that forms two current paths in which magnetic flux of the same strength is generated from one conductor through which the measurement detection current flows, and arranges these paths around the magnetic detection element (magnetic sensor) to increase the output of the magnetic detection element (magnetic sensor) to the measurement detection current (to increase the sensitivity to the measurement detection current). (For example, see Figures 1 and 2 of Patent Document 2.) [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 2022-52554 [Patent Document 2] Patent No. 6696571 Summary of the Invention [Problem to be solved by the invention]

[0006] As stated in the problem that Patent Document 1 aims to solve, with coreless current sensors, as the frequency of the current to be measured increases, the distribution around the conductor changes due to the skin effect, resulting in a problem of reduced sensitivity in the high frequency range.

[0007] In addition, in the current sensor of FIG. 14A of Patent Document 1, the conductors through which the current to be measured and detected flows are arranged at equal pitches, so the distance between the magnetic detection element that detects the magnetic flux generated by the conductor through which the current to be measured and detected flows and the adjacent conductor through which the current not to be measured and detected flows is not uniform. Therefore, if the positional relationship between the conductor through which the current to be measured and detected flows and the magnetic detection element is deviated from the symmetrical relationship due to dimensional errors or assembly variations of the busbar or magnetic detection element, the magnetic detection element that is closest to the adjacent conductor is more susceptible to the magnetic flux from the adjacent conductor than the other magnetic detection elements, resulting in a problem that the measurement accuracy of the current sensor deteriorates. (For example, in the control of a three-phase motor, the accuracy of the current sensor is required to be uniformly good for the three phases rather than having good accuracy for one detection phase and poor accuracy for the other detection phases.)

[0008] Furthermore, in order to increase the sensitivity of the coreless current sensor, the current sensor described in Patent Document 2 forms two current paths in which two currents (currents Ia and Ic in FIG. 2 of Patent Document 2) flow in the same direction in a conductor (self-phase conductor) through which a measurement detection current flows, and places two magnetic detection elements (magnetic sensors) for the self-phase at a predetermined distance between the two current paths, thereby increasing the output of the magnetic detection elements with respect to the measurement detection current. By placing the two magnetic detection elements between the two current paths, the magnetic flux generated by the two currents flowing in the same direction is applied to the two magnetic detection elements with opposite polarities (for example, if one is upward polarity in the figure, the other is downward polarity in the figure). The structure is such that the output is increased by subtracting the detection values ​​of the opposite polarities of the two magnetic detection elements.

[0009] In this type of structure, if there is an adjacent phase conductor installed adjacent to the own phase conductor, the two current paths of the adjacent phase conductor are located outside the two magnetic detection elements for the own phase. Therefore, the magnetic fluxes generated by the two currents flowing in the same direction in the two current paths of the adjacent phase conductor are compounded and increased in the same direction, and are applied with the same polarity to the two magnetic detection elements of the own phase. Since these two magnetic detection elements are separated by a certain distance, there is a level difference between the detection values, which cannot be offset by subtraction. There was a problem that the influence of the adjacent conductor current on the magnetic detection elements becomes worse due to the increase in the number of current paths to two, compared to when there is only one current path.

[0010] As described above, an object of the present invention is to provide a small coreless current sensor that does not lose sensitivity even in high frequency ranges, is less susceptible to the influence of magnetic flux generated by current flowing through adjacent conductors, and is capable of measuring small currents with high accuracy. [Means for solving the problem]

[0011] The current sensor of the present invention includes three or more conductors extending generally parallel to a predetermined X-axis direction, and a pair of first and second magnetic detection elements adjacent to the conductors for detecting magnetic flux generated by a current to be measured flowing through the conductors, and outputs a value equivalent to the difference between the magnetic flux densities detected by the first and second magnetic detection elements for each pair of conductors, the current sensor including a first detection section extending in a direction generally parallel to the Y-axis direction and forming an angle of 90 degrees with respect to the X-axis direction, and a second detection section extending in a direction generally opposite to the direction of extension of the first detection section, The first and second magnetic detection elements detect magnetic flux density in a direction approximately parallel to the Z-axis direction which is at an angle of 90 degrees to both the X-axis direction and the Y-axis direction, the first and second magnetic detection elements are arranged at positions sandwiching either the first or second detection unit from the X-axis direction, the multiple conductors are arranged approximately parallel to the Z-axis direction, the X-axis direction positions of the centers of the first and second magnetic detection elements adjacent to one conductor among the multiple conductors are approximately identical to the X-axis direction positions of the centers of the first and second detection units of an adjacent conductor, and the shortest distances between the centers of the first and second magnetic detection elements adjacent to one conductor among the multiple conductors and the center of the Y-axis / Z-axis cross section of the adjacent conductor are both approximately identical. Effect of the Invention

[0012] According to the present invention, it is possible to provide a small current sensor that is not easily affected by a magnetic flux generated by a current flowing through an adjacent phase conductor. [Brief description of the drawings]

[0013] [Figure 1] 1 is an external perspective view of a current sensor according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is an exploded perspective view of a current sensor according to a first embodiment of the present invention. [Diagram 3] FIG. 2 is a front view of a bus bar of the current sensor according to the first embodiment of the present invention. [Figure 4]FIG. 1 is a diagram illustrating a positional relationship between a bus bar and a magnetic detection element of a current sensor according to a first embodiment of the present invention. [Figure 5A] FIG. 2 is a front view of a bus bar of the current sensor according to the first embodiment of the present invention. [Figure 5B] 2 is a diagram showing the positional relationship between a detection portion of a bus bar and a magnetic detection element of the current sensor according to the first embodiment of the present invention. [Figure 6] 1 is a diagram showing a circuit configuration of a circuit section of a current sensor according to a first embodiment of the present invention. [Figure 7] 2 is a diagram illustrating the positional relationship between the bus bars and the magnetic detection element of the current sensor according to the first embodiment of the present invention. FIG. [Figure 8] FIG. 4 is a diagram illustrating simulation conditions for the current sensor according to the first embodiment of the present invention. [Figure 9A] 4 is a graph showing an attenuation rate at each magnetic sensing point of the current sensor according to the first embodiment of the present invention. [Figure 9B] 4 is a graph showing magnetic flux density values ​​at 60 Hz at each magnetic sensing point of the current sensor according to the first embodiment of the present invention. [Figure 10] 4 is a table showing the influence of a current flowing in an adjacent phase of the current sensor according to the first embodiment of the present invention. [Figure 11] 1 is a diagram illustrating the positional relationship between a bus bar and a circuit portion in the current sensor of Patent Document 1. FIG. [Figure 12] 1 is a table showing the influence of a current flowing in an adjacent phase of the current sensor of Patent Document 1. [Figure 13] FIG. 11 is an exploded perspective view of a current sensor according to a second embodiment of the present invention. [Figure 14A] FIG. 11 is a front view of a bus bar of a current sensor according to a second embodiment of the present invention. [Figure 14B] FIG. 11 is a bottom view of the busbar of the current sensor according to the second embodiment of the present invention. [Figure 14C] FIG. 11 is a rear view of the bus bar of the current sensor according to the second embodiment of the present invention. [Figure 15] FIG. 11 is a diagram illustrating a positional relationship between a bus bar and a magnetic detection element of a current sensor according to a second embodiment of the present invention. [Figure 16A] FIG. 11 is a development view of a bus bar of a current sensor according to a second embodiment of the present invention. [Figure 16B] 10 is a diagram illustrating a positional relationship between a bus bar and a magnetic detection element of a current sensor according to a second embodiment of the present invention. [Figure 17] 10 is a diagram illustrating the positional relationship between a bus bar and a magnetic detection element of a current sensor according to a second embodiment of the present invention. FIG. [Figure 18A] 10 is a table showing magnetic flux density values ​​when a current flows through a phase of the current sensor according to the second embodiment of the present invention. [Figure 18B] 1 is a table showing magnetic flux density values ​​when a current is passed through the own phase of the current sensor of Patent Document 1. [Figure 19] 11 is a table showing the influence of a current flowing in an adjacent phase of the current sensor according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, a current sensor according to each embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are given the same reference characters, and the description thereof will not be repeated.

[0015] First embodiment FIG. 1 is an external perspective view of a current sensor 100 according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view of the current sensor 100 according to the first embodiment of the present invention.

[0016] As shown in FIG. 2, the current sensor 100 has three bus bars 20 (made of, for example, copper, copper alloy, or aluminum, with the U phase at 20U, the V phase at 20V, and the W phase at 20W) for passing current through each phase (U phase, V phase, and W phase) of a three-phase motor (not shown), which are housed and fixed in a case portion 30 (made of, for example, polyphenylene sulfide resin or polybutylene terephthalate resin) by insert molding or adhesive fixing.

[0017] Reference numeral 16 denotes a printed circuit board, on which are soldered and fixed circuitry 10 (10U for U phase, 10V for V phase, and 10W for W phase) that measures the current flowing through bus bars 20U, 20V, and 20W, as well as electronic components such as capacitors (not shown) and resistors (not shown). Signal terminals 40 that input the control power supply for circuit units 10U, 10V, and 10W and output the measurement current signals of circuit units 10U, 10V, and 10W to the outside of current sensor 100 are soldered to printed circuit board 16, and are fixed to screw boss portions 31 of case portion 30 with fixing screws 50.

[0018] Here, in Figures 1 and 2, the thickness direction of busbars 20U, 20V, and 20W is defined as the Z-axis direction, the width direction perpendicular to the thickness direction is defined as the Y-axis direction, and the extension direction perpendicular to the thickness direction and the width direction is defined as the X-axis direction.

[0019] Bus bars 20U, 20V, and 20W extend to, for example, a three-phase motor (not shown) on one side to which they are connected and an inverter (not shown) that drives the three-phase motor on the other side, but only a portion of them is shown in the figure.

[0020] Fig. 3 is a front view of busbar 20U of current sensor 100 according to embodiment 1 of the present invention. As shown in Fig. 3, busbar 20U has three cutout portions 21a, 21b, and 21c, with first cutout portion 21a being cut out in a substantially rectangular shape in the -Y-axis direction from the upper end of busbar 20U in the figure, second cutout portion 21b being cut out in the +Y-axis direction from the lower end of busbar 20U in the figure, and third cutout portion 21c being cut out in a substantially rectangular shape in the -Y-axis direction from the upper end of busbar 20U in the figure.

[0021] Here, the predetermined length in the X-axis direction of the first cutout portion 21a and the third cutout portion 21c is T11, the predetermined length in the Y-axis direction is T13, the predetermined length in the X-axis direction of the second cutout portion 21b is T12, and the predetermined length in the Y-axis direction is T14.

[0022] These cutouts form first detection portion 22a (the conductor portion between first cutout portion 21a and second cutout portion 21b) and second detection portion 22b (the conductor portion between second cutout portion 21b and third cutout portion 21c), which are conductor portions extending in the Y-axis direction. First detection portion 22a and second detection portion 22b have a predetermined length T15 in the X-axis direction. The length of bus bar 20U in the Y-axis direction is T16.

[0023] Here, busbar 20U is shown as a representative, but busbars 20V and 20W also have first notch portion 21a, second notch portion 21b, third notch portion 21c, first detection portion 22a and second detection portion 22b, and the relative positional relationship between each of busbars 20V and 20W is the same as that of busbar 20U.

[0024] Fig. 4 is a diagram illustrating the positional relationship between busbars 20U, 20V, and 20W and magnetic detection elements 1 and 2 (1U and 2U for U phase, 1V and 2V for V phase, and 1W and 2W for W phase) in circuit units 10U, 10V, and 10W of current sensor 100 according to the first embodiment of the present invention. In order to make it easier to see the positional relationship between busbars 20U, 20V, and 20W and magnetic detection elements 1U, 2U, 1V, 2V, 1W, and 2W in circuit units 10U, 10V, and 10W of each phase, Fig. 4 illustrates only busbars 20U, 20V, and 20W and circuit units 10U, 10V, and 10W, and shows a front view of them shifted in the Y-axis direction and viewed from the Z-axis direction.

[0025] 4, magnetic detection elements 1U and 2U are built into circuit unit 10U as a pair, both of which have magnetic sensing axes of the same polarity in the Z-axis direction, and the centers of magnetic detection elements 1U and 2U are disposed a predetermined distance P apart in the X-axis direction and a predetermined distance h apart from the end of first cutout portion 21a in the Y-axis direction. The same is true for magnetic detection elements 1V and 2V built into circuit unit 10V and magnetic detection elements 1W and 2W built into circuit unit 10W.

[0026] In FIG. 4, the central position between the X-axis center of the first detection portion 22a and the X-axis center of the second detection portion 22b of busbar 20W is at the same position in the X-axis direction as the central position (called reference line J) between the X-axis center of the first detection portion 22a and the X-axis center of the second detection portion 22b of busbar 20U, and the central position (called reference line K) between the X-axis center of the first detection portion 22a and the X-axis center of the second detection portion 22b of busbar 20V is at a position shifted a predetermined distance M to the left in the X-axis direction (+X-axis direction) from reference line J in the X-axis direction.

[0027] Here, the positional relationship between the reference line K and the first detection portion 22a of the busbars 20U and 20W is determined so as to coincide with the center position in the X-axis direction of the first detection portion 22a, the center position between the center of the magnetic detection element 1U and the center of the magnetic detection element 2U of the circuit portion 10U, and the center position between the center of the magnetic detection element 1W and the center of the magnetic detection element 2W of the circuit portion 10W. The positional relationship between the reference line J and the second detection portion 22b of the busbar 20V is determined so as to coincide with the center position in the X-axis direction of the second detection portion 22b of the busbar 20V and the center position between the center of the magnetic detection element 1V and the center of the magnetic detection element 2V of the circuit portion 10V. Note that, in FIG. 4, the magnetic detection elements 1U, 2U, 1W, and 2W are disposed near the first detection portion 22a, and the magnetic detection elements 1V and 2V are disposed near the second detection portion 22b, but the magnetic detection elements 1U, 2U, 1W, and 2W may be disposed near the second detection portion 22b, and the magnetic detection elements 1V and 2V may be disposed near the first detection portion 22a.

[0028] Next, the current measurement principle of current sensor 100 according to embodiment 1 of the present invention will be described using busbar 20U as a representative example with reference to Figures 5 and 6. Figure 5A is a front view of busbar 20U. Figure 5B is a diagram showing the positional relationship between first detection portion 22a and second detection portion 22b of busbar 20U and magnetic detection elements 1U and 2U of circuit unit 10U, and is a cross-sectional view of first detection portion 22a and second detection portion 22b of busbar 20U and magnetic detection elements 1U and 2U of circuit unit 10U taken in the XZ plane at the positions of magnetic detection elements 1U and 2U.

[0029] In Fig. 5A, arrows Ia to Id indicate the direction of current flow at a certain point in time of the current to be measured. Near both ends of the busbar 20U in the X-axis direction (extending in the X-axis direction), the current mainly flows in the +X-axis direction as indicated by arrows Ia and Id, in the second detection portion 22b extending in the +Y-axis direction as indicated by arrow Ib, and in the first detection portion 22a extending in the -Y-axis direction forming an angle of 180 degrees with the extension direction of the second detection portion 22b, the current flows in the -Y-axis direction as indicated by arrow Ic. As a result, in Fig. 5B, a magnetic flux La rotating clockwise as shown is generated around the first detection portion 22a, and a magnetic flux Lb rotating counterclockwise as shown is generated around the second detection portion 22b.

[0030] 5B, the magnetic detection elements 1U and 2U are arranged in a direction that provides them with detection sensitivity of the same polarity to magnetic flux in the Z-axis direction. As a result, the magnetic detection elements 1U and 2U detect magnetic fluxes La and Lb that are generated mainly by the current flow directions Ib and Ic of the current flowing through the bus bar 20U. Here, the magnetic detection element 1U detects magnetic fluxes in the -Z-axis direction, and the magnetic detection element 2U detects magnetic fluxes in the opposite directions to each other, that is, in the +Z-axis direction.

[0031] Next, a circuit configuration of the circuit section 10 of the current sensor 100 according to the first embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 is a block diagram showing the circuit configuration of the circuit section 10 of the current sensor 100 according to the first embodiment of the present invention. The circuit section 10 shown in Fig. 6 is disposed at a predetermined position with respect to a conductor 20 through which a current to be measured flows, thereby measuring the current to be measured. The circuit section 10 includes a pair of magnetic detection elements 1, 2, a drive section 3, a control section 4, a first amplifier section 5, a second amplifier section 6, a differential calculation section 7, an output section 8, and a storage section 9.

[0032] The magnetic detection elements 1 and 2 operate using a voltage or current supplied from a driving unit 3, and detect a magnetic flux generated by a current to be measured flowing through a conductor 20. Then, the magnetic detection elements 1 and 2 output a magnetic flux detection signal to a first amplifier unit 5 and a second amplifier unit 6, respectively.

[0033] The magnetic detection elements 1 and 2 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 magnetoresistance effect. A GMR element is an element that detects magnetic flux using the giant magnetoresistance effect. A TMR element is an element that detects magnetic flux using the tunnel effect. In addition to these, any element can be used as the magnetic detection elements 1 and 2 as long as it can detect magnetic flux and output a detection signal according to the detection result.

[0034] The first amplifier 5 and the second amplifier 6 amplify the detection signals output from the magnetic detection elements 1 and 2, respectively, and output the amplified signals to the differential calculation unit 7. The differential calculation unit 7 performs differential calculation to obtain the difference between the measurement values ​​represented by the detection signals output from the first amplifier 5 and the second amplifier 6, respectively, and outputs the calculation result to the output unit 8. The output unit 8 outputs a current corresponding to the difference value obtained by the differential calculation unit 7 to the load resistor 14 via the output terminal 13. As a result, a voltage corresponding to the value of the current to be measured flowing through the conductor 20 is generated between both ends of the load resistor 14, and the measurement result of the current to be measured can be obtained. The circuit unit 10 includes a positive power supply terminal 11 and a negative power supply terminal 12 for supplying a positive power supply and a negative power supply, respectively. One terminal of the load resistor 14 is connected to the output terminal 13, and the other terminal is connected to the negative power supply terminal 12.

[0035] The control unit 4 is configured using, for example, an integrated circuit or a microcomputer, and has a function of adjusting the voltage or current supplied by the drive unit 3 to the magnetic detection elements 1 and 2, and the amplification factors of the first amplification unit 5, the second amplification unit 6, and the differential calculation unit 7. The amplification factors and other setting values ​​used by the control unit 4 during adjustment are stored in a memory unit 9.

[0036] The substrate 15 is made of, for example, a silicon substrate or a glass epoxy substrate, and fixes each of the components of the circuit unit 10 described above in a predetermined arrangement and electrically connects each of the components to each other. The circuit unit 10 on which each component is mounted on the substrate 15 is molded with resin and then attached to the conductors (bus bars 20U, 20V, 20W) in predetermined positions. This allows the pair of magnetic detection elements 1 and 2 to be arranged in the aforementioned positions relative to the conductors (bus bars 20U, 20V, 20W) via the substrate 15.

[0037] Next, the positional relationship in the Z-axis direction between circuit units 10U, 10V, and 10W and bus bars 20U, 20V, and 20W will be described with reference to FIG.

[0038] Fig. 7 is a diagram illustrating the positional relationship in the Z-axis direction between busbars 20U, 20V, 20W and circuit units 10U, 10V, 10W of current sensor 100 according to the first embodiment of the present invention. Fig. 7 is a plan view showing only circuit units 10U, 10V, 10W and busbars 20U, 20V, 20W to make the positional relationship easier to see.

[0039] 7, t indicates the plate thickness of busbars 20U, 20V, and 20W, and 20Us, 20Vs, and 20Ws are center lines indicating the center of the thickness (Z-axis direction) of busbars 20U, 20V, and 20W, respectively. 10Us, 10Vs, and 10Ws are center lines indicating the center in the Z-axis direction of magnetic detection elements 1 and 2 in circuit units 10U, 10V, and 10W, respectively. u is the distance between center line 10Ws and the outer shape of the package of circuit unit 10W, and Q5 is the maximum outer shape distance in the Z-axis direction.

[0040] In Figure 7, the positional relationship of these elements is determined so that the distance Q1 between the center line 20Vs of the busbar 20V in the Z-axis direction and the center line 10Us of the magnetic detection elements 1U and 2U of the adjacent circuit section 10U, the distance Q2 between the center line 20U of the busbar 20U and the center line 10Vs of the magnetic detection elements 1V and 2V of the adjacent circuit section 10V, the distance Q3 between the center line 20Ws of the busbar 20W and the center line 10Vs of the magnetic detection elements 1V and 2V of the adjacent circuit section 10V, and the distance Q4 between the center line 20Vs of the busbar 20V and the center line 10Ws of the magnetic detection elements 1W and 2W of the adjacent circuit section 10W coincide with each other. In this case, center lines 20Us, 20Vs, 20Ws of bus bars 20U, 20V, 20W and center lines 10Us, 10Vs, 10Ws of magnetic detection elements 1, 2 of circuit sections 10U, 10V, 10W are arranged at a predetermined distance D from each other.

[0041] In the current sensor 100 configured as above, the high-frequency current characteristics of the current to be measured will first be described.

[0042] Here, the attenuation rate of the magnetic flux density detected by the magnetic detection elements 1 and 2 when a high-frequency current is passed through the busbar 20 is verified by simulation. FIG. 8 is an explanatory diagram of the simulation conditions, and is a basic model diagram in which the first detection unit 22a and the magnetic detection elements 1U and 2U are cut out from FIG. 5B, which shows the current measurement principle. As shown in FIG. 8, 20a is a conductor extending in the Y-axis direction, and W and t are the conductor width and conductor plate thickness of the conductor 20a. D is the distance in the Z-axis direction between the center of the plate thickness of the conductor 20a and the magnetic flux density measurement point (hereinafter referred to as the magnetic sensing point, which corresponds to the position of the magnetic detection elements 1 and 2), and E is the distance in the X-axis direction between the center of the width of the conductor 20a and the magnetic sensing point.

[0043] The simulation conditions are W = 2 mm, t = 0.8 mm, the position of the magnetic sensing point is between E = +1 mm and +3 mm at the right end in the width direction of the conductor 20a in the figure, and between E = -1 mm and -3 mm at the left end in the figure, and D is changed from 70% to 145% (1.4 mm to 2.9 mm) of W. A current (e.g., 100 A) is passed through the conductor 20a, and the frequency of the current to be measured is the commercial frequency of 60 Hz and the high frequency of 100 kHz.

[0044] 9A is a graph showing the attenuation rate of the magnetic flux density value at each magnetic sensing point, and shows the attenuation rate (vertical axis) when D=1.4 mm, 1.9 mm, 2.4 mm, and 2.9 mm. Here, the attenuation rate is the ratio (ab) / a, where a is the magnetic flux density generated in the Z-axis direction at the magnetic sensing point when a 60 Hz current (e.g., 100 A) is passed through conductor 20a, and b is the magnetic flux density generated in the Z-axis direction when a 100 kHz current (e.g., 100 A) is passed through conductor 20a.

[0045] Fig. 9B is a graph showing the magnetic flux density value at 60 Hz at each magnetic sensing point. As shown in Fig. 9A, the larger the absolute value of the magnetic sensing point distance E in the X-axis direction, the smaller the attenuation rate, and when the absolute value of E is 1.6 mm or more (80% of the conductor 20a width W ratio), the smaller the magnetic sensing point distance D in the Z-axis direction, the smaller the attenuation rate. Also, as shown in Fig. 9B, the smaller the magnetic sensing point distance D in the Z-axis direction, the larger the magnetic flux density value (absolute value).

[0046] Therefore, by setting the absolute value of the distance E of the magnetic sensing point in the X-axis direction to 80% (1.6 mm) or more of the width W of the conductor 20a, the measurable magnetic flux density value is large, the attenuation rate of high-frequency current is small, and highly accurate current measurement is possible from low frequency current to high frequency current.

[0047] 9B, when the absolute value of the magnetic sensing point distance E in the X-axis direction is increased, the magnetic flux density value (absolute value) gradually increases and then decreases, exhibiting a change with a peak point. In other words, by making the relationship between the magnetic sensing point distance E in the X-axis direction and the magnetic sensing point distance D in the Z-axis direction a peak point relationship, a larger magnetic flux density value can be measured.

[0048] For example, when D = 1.4 mm (70% of the width W of the conductor 20a), the peak point is E = 1.7 mm (85% of the width W of the conductor 20a), when D = 1.65 mm (82.5% of the width W of the conductor 20a), the peak point is E = 2 mm (100% of the width W of the conductor 20a), and when D = 1.9 mm (95% of the width W of the conductor 20a), the peak point is E = 2.2 mm (110% of the width W of the conductor 20a).

[0049] On the other hand, if the absolute value of the magnetic sensing point distance E in the X-axis direction is increased, the interval between magnetic detection elements 1 and 2 becomes larger, and magnetic detection elements 1 and 2 are no longer equally affected by the magnetic field (external magnetic field) generated from outside current sensor 100, making it difficult to reduce the influence of the external magnetic field by offsetting the detected values ​​of the magnetic flux densities of both by differential calculation. Therefore, there are cases where it is preferable for the absolute value of the magnetic sensing point distance E in the X-axis direction to be small.

[0050] When the absolute value of the magnetic sensing point distance E in the X-axis direction is 1.6 mm or less (80% of the conductor 20a width W), the attenuation rate decreases as the magnetic sensing point distance D in the Z-axis direction increases, which is the opposite of the above. For example, when E = ±1 mm, the maximum attenuation rate when D = 1.4 mm is 11%, exceeding 10%, whereas the attenuation rates when D = 1.65 mm, 1.9 mm, 2.4 mm, and 2.9 mm are 9%, 9%, 8%, and 6%, respectively. In this way, by setting D = 1.65 mm (82.5% of the conductor 20a width W) or more, it is possible to keep the attenuation rate for high frequencies to 9% or less.

[0051] Therefore, when the absolute value of the X-axis direction distance E of the magnetic sensing point is 80% (1.6 mm) or less relative to the width W of the conductor 20a, it is not preferable to reduce the Z-axis direction distance D of the magnetic sensing point. By setting D to 1.65 mm (82.5% relative to the width W of the conductor 20a) or more, the attenuation rate during high-frequency current measurement is small, and high-precision current measurement is possible from low-frequency current to high-frequency current.

[0052] Next, the magnetic influence that a circuit section 10 of a certain phase (hereinafter referred to as the circuit section of the own phase) receives from a current flowing through a busbar of an adjacent phase (hereinafter referred to as an adjacent phase. For example, if the own phase is the U phase, the adjacent phases are the V phase and the W phase) will be described. FIG. 10 is a table showing the influence of a current flowing through an adjacent phase in current sensor 100 according to the first embodiment of the present invention. Here, taking into consideration dimensional errors and variations during assembly, a case is shown in which the positions of magnetic detection elements 1U, 2U, 1V, 2V, 1W, and 2W shown in FIG. 4 in the X-axis direction are shifted by 0.5 mm in the -X-axis direction with respect to busbars 20U, 20V, and 20W. (The shift in the X-axis direction that is most affected by the adjacent phase current is shown.)

[0053] 10 shows the ratio B / A, where A is the output of circuit section 10 of the own phase (the difference between the detected values ​​of magnetic flux density in the Z-axis direction detected by magnetic detection elements 1 and 2 of circuit section 10 of the own phase) when a predetermined current (e.g., DC 100A) is passed only through the own phase, and B is the output of circuit section 10 of the own phase when no current is passed through the own phase and a predetermined current (e.g., DC 100A) is passed through the adjacent phase that has the greater influence. A and B were obtained by a three-dimensional magnetic field analysis simulation.

[0054] The simulation conditions are T11=1mm, T12=2mm, T13=T14=5.9mm, T15=2mm, T16=7.9mm in Fig. 3, P=2.5mm, M=2mm, h=3.63mm in Fig. 4, and Q5=19.7mm, D=1.9mm, t=0.8mm, u=0.6mm in Fig. 7. Furthermore, under the above conditions, Q2+Q3=Q5-uDt / 2=19.7-0.6-1.9-0.8 / 2=16.8mm, and Q1=Q2=Q3=Q4=8.4mm.

[0055] As shown in Figure 10, when the U phase is the own phase, the influence of the adjacent phase current in the circuit section 10 of the own phase is large, at 0.36%, when the V phase is the own phase, the influence of the adjacent W phase is large, at 0.31%, and when the W phase is the own phase, the influence of the adjacent V phase is large, at 0.33%, and the maximum value of these is 0.36%.

[0056] Here, a comparison with the conventional example will be made using Figure 14A of Patent Document 1 as an example. Figure 11 is a diagram for explaining the positional relationship in the Z-axis direction of busbars 20U, 20V, 20W and circuit units 10U, 10V, 10W that are arranged at equal intervals in Patent Document 1 (conventional example). Figure 11 is a plan view that shows only circuit units 10U, 10V, 10W and busbars 20U, 20V, 20W to make the positional relationship easier to see.

[0057] In FIG. 11, the distance in the Z-axis direction between the center line 20Vs of the busbar 20V and the center line 10Us of the magnetic detection elements 1U and 2U of the adjacent circuit section 10U is Q11, the distance between the center line 20Ws of the busbar 20W and the center line 10Vs of the magnetic detection elements 1V and 2V of the adjacent circuit section 10V is Q13, the distance between the center line 20Us of the busbar 20U and the center line 10Vs of the magnetic detection elements 1V and 2V of the adjacent circuit section 10V is Q12, and the distance between the center line 20Vs of the busbar 20V and the center of the center line 10Ws of the magnetic detection elements 1W and 2W of the adjacent circuit section 10W is Q14. Since the busbars 20U, 20V, and 20W are arranged at equal intervals, the distances Q11 and Q13 are smaller than the distances Q12 and Q14.

[0058] For example, if the maximum outer distance Q15 in the Z-axis direction is 19.7 mm, the same as Q5 in Fig. 7 of this embodiment, then Q12+Q13=Q15-uDt / 2=19.7-0.6-1.9-0.8 / 2=16.8 mm, and since Q12+Q13=2×Q13+2×D, Q13=Q11=(16.8-2×1.9) / 2=6.5 mm. Compared to the distances Q1 to Q4 in Fig. 7, which are 8.4 mm, the distances Q11 and Q13 are 6.5 mm, which is smaller.

[0059] The conventional influence of current flowing into adjacent phases will be verified by simulation below. Fig. 12 is a table showing the influence of current flowing into adjacent phases in the conventional current sensor of Patent Document 1. In Fig. 12, A and B are obtained by a three-dimensional magnetic field analysis simulation as in Fig. 10.

[0060] The simulation conditions are different from those of the first embodiment (FIG. 7) in that the distances in FIG. 11 are Q11=Q13=6.5 mm and Q12=Q14=10.3 mm.

[0061] As shown in Figure 12, when the U phase is the own phase, the influence of the adjacent phase current in the circuit section 10 of the own phase is large, at 1.03%, when the V phase is the own phase, the influence of the adjacent U phase is large, at 1.11%, and when the W phase is the own phase, the influence of the adjacent V phase is large, at 0.13%, and the maximum value of these is 1.11%.

[0062] Furthermore, in order to make the maximum influence of the adjacent phase current equivalent to 0.36% in the first embodiment, it is necessary to make Q11 = Q13 = 12.15 mm, Q12 = Q14 = 8.35 mm, and Q15 = 23.4 mm, and the maximum outer width becomes 1.19 times larger than that of the first embodiment.

[0063] As described above, in this embodiment 1, it is possible to reduce the influence of the adjacent phase current on the circuit section 10 of the own phase by 67%, from the conventional 1.11% to 0.36%, making it possible to perform high-precision measurements without increasing the maximum external dimensions.

[0064] Embodiment 2 13 is an exploded perspective view of current sensor 200 according to embodiment 2 of the present invention. Note that current sensor 200 according to embodiment 2 differs from embodiment 1 in the shape of busbar 60, as well as the relative position of circuit section 10 with respect to busbar 60 and the positional relationship between busbars 60. Case 32 also differs from embodiment 1 in the position of the insertion groove for busbar 60. Note that the same reference characters are used for configurations that are similar to those of current sensor 100 according to embodiment 1, and description thereof will not be repeated.

[0065] First, busbars 60 (60U for U-phase, 60V for V-phase, and 60W for W-phase) of current sensor 200 will be described, taking U-phase busbar 60U as a representative.

[0066] Figure 14A is a front view of the U-phase busbar 60U of the current sensor 200 according to embodiment 2 of the present invention, as viewed from the +Z-axis direction, Figure 14B is a bottom view as viewed from the -Y-axis direction, and Figure 14C is a rear view as viewed from the -Z-axis direction.

[0067] As shown in Figures 14A to 14C, the bus bar 60U has a first path portion 61 extending in the X-axis direction, a second path portion 62 extending from the first path portion 61 in the +Z-axis direction, a third path portion 63 connected to the second path portion 62 and positioned a predetermined distance T27 away from the first path portion 61 in the +Z-axis direction, a fourth path portion 64 extending from the third path portion 63 in the -Z-axis direction, and a fifth path portion 65 connected to the fourth path portion 64 and extending in the -X-axis direction.

[0068] The first path portion 61 and the fifth path portion 65 of the bus bar 60U are spaced apart from each other by a predetermined distance T21 in the -X-axis direction and are disposed on the same XY plane. The third path portion 63 is disposed in a position parallel to the first path portion 61 and the fifth path portion 65.

[0069] 14C , first path portion 61 has two cutout portions 61a and 61b, where first cutout portion 61a has a predetermined length T22 in the X-axis direction and is cut out in a substantially rectangular shape from the illustrated lower end of first conductor portion 61 of busbar 20U in the -Y-axis direction, and second cutout portion 61b has a predetermined length T23 in the X-axis direction and is cut out in a substantially rectangular shape from the illustrated upper end of first path portion 61 of busbar 20U in the +Y-axis direction. Here, the predetermined length of first cutout portion 61a in the Y-axis direction is T24, and the predetermined length of second cutout portion 61b in the Y-axis direction is T25.

[0070] These cutouts provide a first detection portion 61c (a conductor portion between the first cutout portion 61a and the second cutout portion 61b) and a second detection portion 61d (a portion between the second cutout portion 61b and the -X-axis direction end portion of the first path portion 61) which are conductor portions extending in the Y-axis direction. Here, the predetermined length in the X-axis direction of the first detection portion 61c and the second detection portion 61d is T26, the predetermined length in the Y-axis direction of the fifth path portion 65 is T32, and the predetermined length in the Y-axis direction of the first path portion 61 is T33.

[0071] As shown in FIG. 14A, the third path portion 63 has a third detection portion 63a facing the first detection portion 61c at a predetermined distance T27 in the Z-axis direction, a fourth detection portion 63b facing the second detection portion 61d at a predetermined distance T27 in the Z-axis direction, a first connection portion 63c connecting the third detection portion 63a and the fourth detection portion 63b, and a second connection portion 63d connecting the fourth detection portion 63b and the fourth path portion 64. The third detection portion 63a has a Y-axis length (linear distance in the Y-axis direction of the third detection portion) T29, and the fourth detection portion 63b has a predetermined length in the Y-axis direction (linear distance in the Y-axis direction of the fourth detection portion) T28, and is present at a predetermined distance T23 in the X-axis direction from the third detection portion 63a. T30 is the Y-axis length of the first connection portion 63c, and T31 is the Y-axis length of the second connection portion 63d (connection side with the fourth detection portion 63b).

[0072] The first detection portion 61c and the third detection portion 63a, and the second detection portion 61d and the fourth detection portion 63b are shaped to face each other at a predetermined distance T27 in the Z-axis direction, and when the bus bar 60U is formed by press processing, it is preferable to bend the second path portion 62 and the fourth path portion 64.

[0073] In both V-phase busbar 60V and W-phase busbar 60W, the positional relationships between first detection portion 61c, second detection portion 61d, third detection portion 63a and fourth detection portion 63b are the same as those of U-phase busbar 60U.

[0074] Fig. 15 is a diagram illustrating the positional relationship between busbars 60U, 60V, 60W and magnetic detection elements 1U, 2U, 1V, 2V, 1W, 2W in circuit units 10U, 10V, 10W of current sensor 200 according to embodiment 2 of the present invention. In order to make it easier to see the positional relationship between busbars 60U, 60V, 60W and magnetic detection elements 1U, 2U, 1V, 2V, 1W, 2W in circuit units 10U, 10V, 10W of each phase, Fig. 15 illustrates only busbars 60U, 60V, 60W and circuit units 10U, 10V, 10W, and shows a front view of them shifted in the Y-axis direction and viewed from the Z-axis direction.

[0075] As shown in FIG. 15, busbar 60V is shaped such that the first detection portion 61c, the second detection portion 61d, the third detection portion 63a and the fourth detection portion 63b are shifted a predetermined distance M in the +X-axis direction relative to busbars 60U and 60W.

[0076] Here, the reference line J is the center position between the X-axis direction center of the first detection portion 61c and the X-axis direction center of the second detection portion 61d of the busbars 60U and 60W, and the reference line K is the center position between the X-axis direction center of the first detection portion 61c and the X-axis direction center of the second detection portion 61d of the busbar 60V. The positional relationship between the reference line K and the X-axis direction center positions of the first detection portion 61c and the third detection portion 63a of the busbars 60U and 60W, the center position between the center of the magnetic detection element 1U and the center of the magnetic detection element 2U of the circuit unit 10U, and the center position between the center of the magnetic detection element 1W and the center of the magnetic detection element 2W of the circuit unit 10W is determined. The positional relationship between the reference line J and the X-axis direction center positions of the second detection portion 61d and the fourth detection portion 63b of the busbar 60V, and the center position between the center of the magnetic detection element 1V and the center of the magnetic detection element 2V of the circuit unit 10V is determined. In FIG. 15, magnetic detection elements 1U, 2U, 1W, and 2W are arranged near the first detection portion 61c, and magnetic detection elements 1V and 2V are arranged near the second detection portion 61d, but magnetic detection elements 1U, 2U, 1W, and 2W may be arranged near the second detection portion 61d, and magnetic detection elements 1V and 2V may be arranged near the first detection portion 61c.

[0077] Next, the current measurement principle of current sensor 200 according to the second embodiment of the present invention will be described using busbar 60U as a representative with reference to Fig. 16. Fig. 16A is a development view of busbar 60U (shape before bending). Fig. 16B is a diagram showing the positional relationship between first detection portion 61c, second detection portion 61d, third detection portion 63a, and fourth detection portion 63b of busbar 60U, and magnetic detection elements 1U and 2U of circuit unit 10U, and is a cross-sectional view of first detection portion 61c, second detection portion 61d, third detection portion 63a, and fourth detection portion 63b of busbar 60U, and magnetic detection elements 1U and 2U of circuit unit 10U, cut in the XZ plane at the positions of magnetic detection elements 1U and 2U.

[0078] In Fig. 16A, arrows Ia to Id indicate the direction of current flow at a certain point in time of the measured current. Near both ends of the busbar 60U in the X-axis direction (extending in the X-axis direction), the current mainly flows in the +X-axis direction as indicated by arrows Ia and Id, in the second detection section 61d extending in the +Y-axis direction as indicated by arrow Ib1, and in the first detection section 61c extending in the -Y-axis direction forming an angle of 180 degrees with the extension direction of the second detection section 61d, the current flows in the -Y-axis direction as indicated by arrow Ic1. In addition, in the third detection section 63a and the fourth detection section 63b, in the shape after bending, the current flows in the direction opposite to the arrows shown in Fig. 16A, so that in the fourth detection section 63b, the current flows in the +Y-axis direction opposite to the direction indicated by arrow Ib2, and in the third detection section 63a, the current flows in the -Y-axis direction opposite to the direction indicated by arrow Ic2. In FIG. 16A, N1 is a first folding line in the case of press working, and N2 is a second folding line.

[0079] As a result, in FIG. 16B, a clockwise magnetic flux La is generated around the first detection portion 61c and the third detection portion 63a, and a counterclockwise magnetic flux Lb is generated around the second detection portion 61d and the fourth detection portion 63b.

[0080] 16B, the magnetic detection elements 1U and 2U are arranged in a direction that provides detection sensitivity of the same polarity to magnetic flux in the Z-axis direction. As a result, the magnetic detection elements 1U and 2U detect magnetic flux La and Lb that are generated mainly by the current flow directions Ib1, Ib2, Ic1, and Ic2 of the current flowing through the bus bar 60U. Here, the magnetic detection element 1U detects magnetic flux in the -Z-axis direction, and the magnetic detection element 2U detects magnetic flux in the opposite direction to each other, that is, in the +Z-axis direction. As described above, the measurement result of the current to be measured can be obtained in the same manner as in embodiment 1.

[0081] Next, the positional relationship in the Z-axis direction between circuit units 10U, 10V, and 10W and bus bars 60U, 60V, and 60W will be described with reference to FIG.

[0082] Fig. 17 is a diagram illustrating the positional relationship in the Z-axis direction between bus bars 60U, 60V, 60W and circuit units 10U, 10V, 10W of current sensor 200 according to the second embodiment of the present invention. Fig. 17 is a plan view showing only circuit units 10U, 10V, 10W and bus bars 60U, 60V, 60W to make the positional relationship easier to see.

[0083] 17, 60Us, 60Vs, and 60Ws are center lines indicating the center of the thickness (Z-axis direction) of busbars 60U, 60V, and 60W, respectively. 10Us, 10Vs, and 10Ws are center lines indicating the center of the Z-axis direction of magnetic detection elements 1 and 2 in circuit parts 10U, 10V, and 10W, respectively. Q65 is the maximum outer distance in the Z-axis direction.

[0084] 17, the distance Q61 between the center line 60Vs of the busbar 60V and the center line 10Us of the magnetic detection elements 1U and 2U of the adjacent circuit unit 10U in the Z-axis direction is determined to coincide with the distance Q63 between the center line 60Ws of the busbar 60W and the center line 10Vs of the magnetic detection elements 1V and 2V of the adjacent circuit unit 10V. Furthermore, the positional relationship between these is determined to coincide with the distance Q62 between the center line 60Us of the busbar 60U and the center line 10Vs of the magnetic detection elements 1V and 2V of the adjacent circuit unit 10V, and the distance Q64 between the center line 60Vs of the busbar 60V and the center of the center line 10Ws of the magnetic detection elements 1W and 2W of the adjacent circuit unit 10W.

[0085] In the current sensor 200 configured in this manner, we will describe the magnetic flux density that the magnetic detection elements 1 and 2 in the circuit sections 10U, 10V, and 10W receive from the current flowing through the busbar of their respective phase when a current is passed through the busbars 60V, 60U, and 60W of each phase.

[0086] FIG. 18A is a table showing magnetic flux density values ​​when a current is passed through the own phase of current sensor 200 of embodiment 2 of the present invention, and shows the detection value of magnetic flux density in the Z-axis direction detected by magnetic detection elements 1U and 2U of U-phase circuit section 10U when a predetermined current (e.g., DC 100 A) is passed only through the U-phase, and its differential value; the detection value of magnetic flux density in the Z-axis direction detected by magnetic detection elements 1V and 2V of V-phase circuit section 10V when a predetermined current (e.g., DC 100 A) is passed only through the V-phase, and its differential value; and the detection value of magnetic flux density in the Z-axis direction detected by magnetic detection elements 1W and 2W of W-phase circuit section 10W when a predetermined current (e.g., DC 100 A) is passed only through the W-phase, and its differential value, all of which are determined by a 3D magnetic field analysis simulation.

[0087] The simulation conditions were: T21=T22=1mm, T23=2mm, T24=T25=5.9mm, T26=2mm, T32=10mm, T33=7.9mm in Figure 14C; T27=3mm in Figure 14B; T28=3mm, T29=8mm, T30=T31=2mm in Figure 14A; P=2.5mm, M=2mm, h=3.63mm in Figure 15; and Q61=Q63=6.5mm, Q62=Q64=10.3mm, Q65=21.4mm, D=1.9mm, t=0.8mm in Figure 17.

[0088] As shown in Figure 18A, the absolute value of the difference between the magnetic flux densities detected by magnetic detection elements 1U and 2U of the U-phase circuit section 10U is 18.72 mT, the absolute value of the difference between the magnetic flux densities detected by magnetic detection elements 1V and 2V of the V-phase circuit section 10V is 19.00 mT, and the absolute value of the difference between the magnetic flux densities detected by magnetic detection elements 1W and 2W of the U-phase circuit section 10W is 18.61 mT.

[0089] Here, a comparison with the conventional example will be made using FIG. 14A of Patent Document 1 as an example. Figure 18B is a table showing magnetic flux density values ​​when current is passed through the own phase in the conventional current sensor of Figure 14A of Patent Document 1, and shows the detection value of the magnetic flux density in the Z-axis direction detected by magnetic detection elements 1U and 2U of U-phase circuit unit 10U when a predetermined current (e.g., DC 100 A) is passed only through the U-phase and its differential value, the detection value of the magnetic flux density in the Z-axis direction detected by magnetic detection elements 1V and 2V of V-phase circuit unit 10V when a predetermined current (e.g., DC 100 A) is passed only through the V-phase and its differential value, and the detection value of the magnetic flux density in the Z-axis direction detected by magnetic detection elements 1W and 2W of W-phase circuit unit 10V when a predetermined current (e.g., DC 100 A) is passed only through the W-phase and its differential value, all of which are determined by a 3D magnetic field analysis simulation.

[0090] The simulation conditions are the same as the dimensional relationship in FIG. 11 when the influence of the current flowing in the adjacent phase in the conventional current sensor of Patent Document 1 was verified in FIG.

[0091] As shown in Figure 18B, the absolute value of the difference in magnetic flux density detected by magnetic detection elements 1U and 2U of the U-phase circuit section 10U is 9.55 mT, the absolute value of the difference in magnetic flux density detected by magnetic detection elements 1V and 2V of the V-phase circuit section 10V is 8.80 mT, and the absolute value of the difference in magnetic flux density detected by magnetic detection elements 1W and 2W of the W-phase circuit section 10W is 8.83 mT.

[0092] As described above, in this embodiment 2, the absolute value of the difference in magnetic flux density detected by magnetic detection elements 1 and 2 of circuit unit 10 for a current (e.g., 100 A) flowing in the own phase can be increased by 1.96 to 2.11 times, from 9.55 mT to 18.72 mT in the U phase, from 8.80 mT to 19.00 mT in the V phase, and from 8.83 mT to 18.61 mT in the W phase. This makes it possible to perform highly sensitive current measurement in a current range 0.5 times smaller than conventional methods, even when using the same circuit unit 10.

[0093] Next, the effect of the current flowing in the adjacent phase will be described. The influence of the current flowing into the adjacent phase will be verified by simulation below. Fig. 19 is a table showing the influence of the current flowing into the adjacent phase in the current sensor of embodiment 2. In Fig. 19, A and B are obtained by a three-dimensional magnetic field analysis simulation, similar to the above-mentioned Fig. 10, when the influence of the current flowing into the adjacent phase of the current sensor 100 according to embodiment 1 of the present invention was verified. The simulation conditions are the same as those in Fig. 18A described above, except for the dimensional relationship between the fourth detection portion 63b and the third path portion 63d, and the Y-axis direction length T28 of the fourth detection portion 63b is changed to 3 mm, 2 mm, and 1 mm.

[0094] As shown in FIG. 19, the influence of the adjacent phase current of the circuit section 10 of the own phase becomes smaller (improved) as the Y-axis direction length T28 of the fourth detection section 63b is longer and the ratio to the Y-axis direction length T29 of the third detection section 63a is increased. When the ratio to T29 is 12.5% ​​(T28=1 mm), when the U phase is the own phase, the influence of the adjacent phase V phase is large at 0.06%, when the V phase is the own phase, the influence of the adjacent phase U phase is large at 0.68%, and when the W phase is the own phase, the influence of the adjacent phase V phase is large at 0.88%. The maximum values ​​of these are 0.88%, and when the ratio to T29 is 25% (T28=2 mm), the influence of the adjacent phase V phase is large at 0.06%. When the ratio to T29 is 37.5% (T28 = 3 mm), if the U phase is the own phase, the influence of the adjacent V phase is large at 0.05%, when the V phase is the own phase, the influence of the adjacent U phase is large at 0.04%, and when the W phase is the own phase, the influence of the adjacent V phase is large at 0.10%, and the maximum value of these is 0.10%.

[0095] In this way, by setting the ratio of the Y-axis length T28 of the fourth detection portion 63b to the Y-axis length T29 of the third detection portion 63a to be 37.5% or more, high-precision current measurement with little influence of the current flowing in the adjacent phase is possible.

[0096] Moreover, bus bar 60 can be easily formed into a desired shape by bending it at first bending line N1 and second bending line N2 shown in FIG. 16A by press working. [Explanation of symbols]

[0097] 100, 200 Current Sensor 20, 20V, 20V, 20W, 60V, 60V, 60W Busbar 16 Printed circuit board section 10, 10U, 10V, 10W circuit section 40 Signal terminal 30 Case part 31 Thread boss 50 Fixing screw 21a First notch 21b Second notch 21c Third cutout T11, T12, T13, T14, T15, T16 specified length 22a First detection unit 22b Second detection unit P, M specified distance 1, 2, 1U, 2U, 1V, 2V, 1W, 2W magnetic detection element, Ia, Ib, Ib1, Ib2, Ic, Ic1, Ic2, Id Current direction La, Lb magnetic flux K, J reference line 3 Drive unit 4. Control section 5 First Amplifier 6 Second Amplifier 7 Differential calculation section 8 Output section 9 Memory section 11 Positive power supply terminal 12 Negative power supply terminal 13 Output terminal 14 Load Resistance 15 Base material t Conductor thickness 20Vs, 20Vs, 20Ws, 60Vs, 60Vs, 60Ws Busbar thickness center 10Vs, 10Vs, 10Ws, 60Vs, 60Vs, 60Ws Magnetic detection element center Q1, Q2, Q3, Q4, Q11, Q12, Q13, Q14, Q61, Q62, Q63, Q64, Q65 distance Q5, Q15, Q65 Maximum external distance W Conductor width 61 First Path Section 62 Second Path Section 63 Third Path Section 64 Fourth Path Section 65 The Fifth Path 61a First notch 61b Second notch 61c First detector 61d Second detector 63a Third detector 63b Fourth detector 63c First connection 63d Third Connection T21, T22, T23, T24, T25, T26, T27, T28, T29, T30, T31 Predetermined length N1 First fold line N2 Second fold line

Claims

1. A current sensor including three or more conductors extending generally parallel to each other in a predetermined X-axis direction, and a pair of first and second magnetic detection elements adjacent to the conductors for detecting magnetic flux generated by a current to be measured flowing through the conductors, the pair including a first magnetic detection element and a second magnetic detection element, the first magnetic detection element and the second magnetic detection element being arranged in a plurality of pairs for each conductor, the current sensor outputting a value corresponding to a difference between magnetic flux densities detected by the first and second magnetic detection elements for each pair, a first detection portion that is disposed in a portion of the conductor and extends in a direction substantially parallel to a Y-axis direction that is at an angle of 90 degrees to the X-axis direction; A second detection portion having an extension direction that forms an angle of approximately 180 degrees (approximately the opposite direction) with respect to the extension direction of the first detection portion, the first and second magnetic detection elements detect a magnetic flux density in a direction substantially parallel to a Z-axis direction that is at an angle of 90 degrees with respect to both the X-axis direction and the Y-axis direction; the first and second magnetic detection elements are disposed at positions sandwiching either the first or second detection unit in the X-axis direction, The plurality of conductors are arranged substantially parallel to the Z-axis direction, the X-axis direction positions of centers of the first magnetic detection element and the second magnetic detection element adjacent to one conductor among the plurality of conductors are substantially the same as the X-axis direction positions of centers of the first detection portion and the second detection portion of an adjacent conductor, A current sensor characterized in that the shortest distances between the centers of the first and second magnetic detection elements adjacent to one of the multiple conductors and the center of the Y-axis / Z-axis cross section of an adjacent conductor are all approximately the same.

2. A current sensor includes a conductor extending substantially parallel to a predetermined X-axis direction, and a pair of first and second magnetic detection elements that detect a magnetic flux generated by a current to be measured flowing through the conductor, and outputs a value corresponding to a difference between magnetic flux densities detected by the first and second magnetic detection elements, a first detection unit and a third detection unit extending in a part of the conductor and extending in a direction substantially parallel to a Y-axis direction that is at an angle of 90 degrees to the X-axis direction; a second detection portion and a fourth detection portion having an extension direction that forms an angle of approximately 180 degrees (approximately the opposite direction) with respect to the extension direction of the first detection portion; the third detection unit faces the first detection unit, the fourth detection unit faces the second detection unit, the first and second magnetic detection elements detect a magnetic flux density in a direction substantially parallel to a Z-axis direction that is at an angle of 90 degrees with respect to both the X-axis direction and the Y-axis direction; A current sensor characterized in that the first and second magnetic detection elements are located either near the first detection portion and the third detection portion, or near the second detection portion and the fourth detection portion, and are arranged in a position that sandwiches the detection portion from the X-axis direction.

3. the conductor has a first bending line substantially parallel to the X-axis direction and a second bending line substantially parallel to the first bending line, and is bent at the first bending line and the second bending line so that the first detection unit and the third detection unit face each other; 3. The current sensor according to claim 2, wherein the second detection portion and the fourth detection portion face each other.

4. 4. The current sensor according to claim 2, wherein the conductors are two or more and arranged approximately parallel to the X-axis direction, and the linear distance in the Y-axis direction of the fourth detection portion of the conductor is 0.375 times or more longer than the linear distance in the Y-axis direction of the third detection portion.

5. A current sensor includes a conductor extending in a predetermined Y-axis direction, and a pair of first and second magnetic detection elements that detect a magnetic flux generated by a current to be measured flowing through the conductor, and outputs a value corresponding to a difference between the magnetic flux densities detected by the first and second magnetic detection elements, a direction of a line connecting a center of the first magnetic detection element and a center of the second magnetic detection element is substantially parallel to an X-axis direction that is at an angle of 90 degrees with respect to the Y-axis direction; the first and second magnetic detection elements detect a magnetic flux density in a direction substantially parallel to a Z-axis direction that is at an angle of 90 degrees with respect to both the X-axis direction and the Y-axis direction; a current sensor characterized in that the X-axis distance between the center of the first magnetic detection element and the center of the X-axis / Z-axis cross section of the conductor, and the X-axis distance between the center of the second magnetic detection element and the center of the X-axis / Z-axis cross section of the conductor are both 0.8 times or more the conductor width in the X-axis direction of the conductor.

6. A current sensor includes a conductor extending in a predetermined Y-axis direction, and a pair of first and second magnetic detection elements that detect a magnetic flux generated by a current to be measured flowing through the conductor, and outputs a value corresponding to a difference between the magnetic flux densities detected by the first and second magnetic detection elements, a direction of a line connecting a center of the first magnetic detection element and a center of the second magnetic detection element is substantially parallel to an X-axis direction that is at an angle of 90 degrees with respect to the Y-axis direction; the first and second magnetic detection elements detect a magnetic flux density in a direction substantially parallel to a Z-axis direction that is at an angle of 90 degrees with respect to both the X-axis direction and the Y-axis direction; the X-axis distance between a center of the first magnetic detection element and a center of the X-axis / Z-axis cross section of the conductor, and the X-axis distance between a center of the second magnetic detection element and a center of the X-axis / Z-axis cross section of the conductor are both equal to or less than 0.8 times the conductor width in the X-axis direction of the conductor, A current sensor characterized in that the Z-axis distance between the center of the first magnetic detection element and the center of the X-axis / Z-axis cross section of the conductor, and the Z-axis distance between the center of the second magnetic detection element and the center of the X-axis / Z-axis cross section of the conductor are both 0.825 times or more the conductor width in the X-axis direction of the conductor.

Images