JP4459011B2 - Current sensor - Google Patents

Description

  The present invention relates to a current sensor that detects the magnitude of a current passing through a current detector using a magnetoelectric conversion element such as a Hall element.

  Such conventional current sensors include those shown in FIGS.

  As shown in FIGS. 6 to 8, the case 101 of the current sensor 100 includes a case main body 103 in which a component accommodating chamber 102 is formed, and a lid (not shown) that is fixed to the upper surface and closes the component accommodating chamber 102. Z)). A through-hole 104 through which a bus bar (not shown) as a current detection body passes is formed in the center of the case main body 103 and the lid (not shown), and the detection current is supplied to the bus bar.

  The component storage chamber 102 stores a core 105 and a substrate 106. The core 105 has a substantially rectangular frame shape, and a gap 105a is formed at one location. A Hall element 107 that is a magnetoelectric conversion element is mounted on the substrate 106, and the Hall element 107 is disposed in the gap 105 a of the core 105.

  In the above configuration, when a detection current is passed through a bus bar (not shown), a magnetic field proportional to the current is generated in the core 105, and the Hall element 107 outputs a voltage value proportional to the magnitude of the generated magnetic field. . As described above, the magnitude of the detection current is detected.

A technique similar to the conventional example is disclosed in, for example, Patent Document 1.
JP-A-6-235735

  However, in the above-described conventional current sensor 100, the range in which the magnitude of the magnetic field generated in the core 105 has linearity with respect to the magnitude of the detected current is the detection range. Therefore, if a core material having a high saturation magnetic flux density is used for the core 105, a wide current detection range can be obtained. However, a material having a high saturation magnetic flux density has a large magnetic hysteresis, so that the current cannot be detected with high accuracy. There is.

  On the other hand, when a core material having a small magnetic hysteresis is used for the core 105, a highly accurate current detection is possible in a low current region. However, a material with a small magnetic hysteresis has a low saturation magnetic flux density, so that the current detection range is high. Cannot take as wide as the basin.

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a current sensor that has a wide current detection range and can perform high-precision detection in a low current region.

The invention of claim 1 includes a first core saturation flux density 1.30～1.50Tesla, a first magneto-electric transducer for converting the magnitude of the magnetic field passing through the first core in an electrical quantity, a magnetic hysteresis A second core having a coercive force of 0.4 to 1.6 A / m and a residual magnetic flux density of 0.30 to 0.45 Tesla; and a second magnetoelectric conversion element that converts the magnitude of the magnetic field passing through the second core into an electric quantity. Are formed in the same case, and a low step surface and a high step surface of the component storage chamber are formed in the case, and the first core, the first magnetoelectric conversion element, and the second core are formed on each step surface. The second magnetoelectric conversion element is arranged at a predetermined interval in the current direction of the detection current.

In this current sensor, a magnetic field proportional to the detection current is generated in the second core in the low current region of the detection current, and a magnetic field substantially proportional to the detection current is generated in the first core in the high current region of the detection current. appear. Further, the first magnetoelectric conversion element and the second magnetoelectric conversion element can detect the magnitude of the magnetic field that is not affected by the mutual leakage magnetic flux as much as possible.

A second aspect of the present invention, a current sensor according to claim 1 Symbol placement, the said case, the first core and the through hole is provided through the center of the second core, detected in the through hole A current detector to which a current is applied is fixed.

In this current sensor, in addition to the operation of the first aspect of the invention, the relative positions of the current detector and the first core and the second core do not vary due to vibration or the like.

According to the invention of claim 1, in the low current region of the detected current, a magnetic field proportional to the detected current is generated in the second core with high accuracy, and in the entire current region from the low current region of the detected current to the high current region, A magnetic field substantially proportional to the detected current is generated in the first core. Therefore, if the output of the first magnetoelectric conversion element is adopted as the detection output in the high current region and the output of the second magnetoelectric conversion element is adopted as the detection output in the low current region, the current detection range is wide, and high accuracy is achieved in the low current region. Can be detected. Further, the first magnetoelectric conversion element and the second magnetoelectric conversion element can be detected so as not to receive interference due to the leakage magnetic flux as much as possible. Therefore, detection accuracy is improved.

According to the invention of claim 2 , in addition to the effect of the invention of claim 1 , the relative position between the current detector and the first core and the second core does not vary due to vibration or the like. Therefore, predetermined output characteristics are always obtained from the first magnetoelectric conversion element and the second magnetoelectric conversion element, and the reliability of the detection output is improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 to 5 show an embodiment of the present invention, FIG. 1 is an exploded perspective view of a current sensor 1, FIG. 2 is a perspective view of the current sensor 1, FIG. 3 is a sectional view of the current sensor 1, and FIG. FIG. 5 is a circuit diagram of the sensor 1, and FIG. 5 is an output characteristic diagram of the first Hall element 12 and the second Hall element 13.

  As shown in FIGS. 1 to 3, the case 2 of the current sensor 1 includes a case main body 4 in which a component housing chamber 3 is formed, and a lid (not shown) that is fixed to the upper surface and closes the component housing chamber 3. Z)). An inner wall portion 4a is erected at the center of the case body 4, and a through hole 5 is formed at the center of the inner wall portion 4a. A bus bar (not shown), which is a current detector, is fixed in the through hole 5 in a state of passing therethrough. The bus bar (not shown) penetrates the centers of the first core 9 and the second core 10 described below. The component housing chamber 3 is surrounded by an inner wall portion 4a and an outer peripheral wall 4b. The outer peripheral side of the bottom surface is formed as a low step surface 6 and the inner peripheral side is formed as a high step surface 7, and the outer side of the low step surface 6 is further high. It is formed on the substrate mounting surface 8 higher than the step surface 7.

  A first core 9 is accommodated on the low step surface 6 on the outer peripheral side of the component storage chamber 3, and a second core 10 is accommodated on the high step surface 7 on the inner peripheral side. The first core 9 is formed in a substantially rectangular frame shape with a ferromagnetic material having a high saturation magnetic flux density (saturation magnetic flux density of about 1.30 to 1.50 Tesla), for example, pure iron or silicon steel. A gap 9 a is formed at one location of the rectangular frame-shaped first core 9. When a magnetic field is generated by an energization current to a bus bar (not shown), a magnetic path of the generated magnetic field is formed in the first core 9. The second core 10 is formed of a ferromagnetic material having a small magnetic hysteresis (coercive force of about 0.4 to 1.6 A / m, residual magnetic flux density of about 0.30 to 0.45 Tesla), for example, a substantially rectangular frame shape with a permalloy material. Is formed. A gap 10 a is formed at one location of the rectangular frame-shaped second core 10. When a magnetic field is generated by an energization current to a bus bar (not shown), a magnetic path of the generated magnetic field is formed in the second core 10.

  A substrate 11 is accommodated on the substrate mounting surface 8 of the component accommodating chamber 3. A first Hall element 12 that is a first magnetoelectric conversion element and a second Hall element 13 that is a second magnetoelectric conversion element are mounted on the substrate 11. The first Hall element 12 is mounted at a position separated from the surface of the substrate 11 and is disposed in the gap 9 a of the first core 9. The second Hall element 13 is mounted at a position close to the surface of the substrate 11 and is disposed in the gap 10 a of the second core 10.

  In this way, the low step surface 6 and the high step surface 7 of the component storage chamber 3 are formed, and the first core 9 and the second core 10 are stored on the respective surfaces, and in the gaps 9a and 10a of the cores 9 and 10, respectively. By arranging the first Hall element 12 and the second Hall element 13, the first core 9, the first Hall element 12, the second core 10 and the second Hall element 13 have a predetermined current flow direction. They are arranged at positions where a gap d (shown in FIG. 3) is opened.

  The case body 4 is integrally provided with a connector portion 14, and the terminal 15 of the connector portion 14 extends to the substrate 11. A power supply is received from the outside via the connector section 14, and the detection outputs of the first and second Hall elements 12, 13 are output together as shown in FIG.

  In the above configuration, when a detection current is passed through a bus bar (not shown), a magnetic field proportional to this current is generated in both the first core 9 and the second core 10, and the magnitude of the magnetic field generated in the first core 9. A voltage proportional to the height is output from the first Hall element 12, and a voltage proportional to the magnitude of the magnetic field generated in the second core 10 is output from the second Hall element 13.

  Here, since the second core 10 is formed of a ferromagnetic material having a small magnetic hysteresis, a magnetic field proportional to the detected current is highly proportional to the detected current in the low current region (± 50 A) of the detected current. As shown in FIG. 5, the second Hall element 13 outputs a highly accurate detection voltage value (output 2). Further, since the first core 9 is formed of a ferromagnetic material having a high saturation magnetic flux density, it is substantially proportional to the detected current over the entire current range (± 400 A) from the low current range to the high current range. The generated magnetic field is generated in the first core 9, and as shown in FIG. 5, the first Hall element 12 outputs a detection voltage value (output 1) substantially proportional to the detection current. Therefore, if the output of the first Hall element 12 is used as the detection output in the high current range and the output of the second Hall element 13 is used as the detection output in the low current range, the current detection range is wide and high accuracy is achieved in the low current range. Can be detected.

  In the above-described embodiment, the first core 9 and the first Hall element 12 and the second core 10 and the second Hall element 13 are arranged at a predetermined interval d with respect to the flow direction of the detected current. The first Hall element 12 and the second Hall element 13 can be detected so as not to receive interference due to the leakage magnetic flux as much as possible. Therefore, in this embodiment, detection accuracy can be improved.

  Further, in the above-described embodiment, the case 2 is provided with the through hole 5 penetrating the centers of the first core 9 and the second core 10, and a bus bar (not shown) through which the detection current is passed in the through hole 5. ) Is fixed, the relative positions of the bus bar and the first core 9 and the second core 10 do not fluctuate due to vibration or the like. Therefore, predetermined output characteristics are always obtained from the first Hall element 12 and the second Hall element 13, and the reliability of the detection output is improved.

  Furthermore, in the above-described embodiment, the detection current is supplied to the bus bar, but the detection current body may be a wire harness or the like.

  In the above-described embodiment, the first and second magnetoelectric conversion elements are the first and second Hall elements 12 and 13, but any element that can convert the strength of the magnetic field into an electric quantity may be used.

It is a disassembled perspective view of the current sensor which concerns on one Embodiment of this invention. It is a perspective view of the current sensor concerning one embodiment of the present invention. It is sectional drawing of the current sensor which concerns on one Embodiment of this invention. It is a circuit diagram of the current sensor concerning one embodiment of the present invention. It is an output characteristic diagram of the 1st hall element and the 2nd hall element concerning one embodiment of the present invention. It is a disassembled perspective view of the conventional current sensor. It is a perspective view of the conventional current sensor. It is sectional drawing of the conventional current sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current sensor 2 Case 5 Through-hole 9 1st core 10 1st Hall element (1st magnetoelectric conversion element)
12 2nd core 13 2nd Hall element (2nd magnetoelectric conversion element)

Claims (2)

A first core having a saturation magnetic flux density of 1.30 to 1.50 Tesla, a first magnetoelectric conversion element for converting the magnitude of a magnetic field passing through the first core into an electric quantity, and a magnetic hysteresis having a coercive force of 0.4 to 1 A second core having a residual magnetic flux density of 0.30 to 0.45 Tesla and a second magnetoelectric conversion element for converting the magnitude of the magnetic field passing through the second core into an electric quantity are provided in the same case. Forming a low step surface and a high step surface of the component housing chamber in the case, wherein the first core and the first magnetoelectric conversion element, the second core and the second magnetoelectric conversion element are formed on the respective step surfaces. Is a current sensor that is arranged at a predetermined interval in the current direction of the detected current. The current sensor according to claim 1,
The case is provided with a through-hole penetrating the center of the first core and the second core, and a current detector to which a detection current is passed is fixed in the through-hole. Sensor.

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