JP2011158337A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminating the effects of a current to measurement accuracy to measure the current by one magnetic sensor even when the other magnetic sensor has failed. <P>SOLUTION: A current sensor is equipped with: a pair of magnetic yoke walls 21 and 22 surrounding a current path to be detected 1 in a loop and opposed to each other by being divided into two by two air gaps arranged at symmetric locations on both sides of the current path to be detected 1; two magnetic sensors 31 and 32 each arranged in the two air gaps 23 and 24 and having magnetic sensing directions along the wall surfaces of the pair of magnetic yoke walls opposed to each other via the air gaps for outputting voltage signals corresponding to a current flowing through the current path to be detected 1 on the basis of the strength of magnetic fields generated according to the current f; and a signal processing circuit 6 for processing signals by the sum of the voltage signals outputted from the two magnetic sensors. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a current sensor that outputs a voltage signal corresponding to the current flowing through the detected current path from the magnitude of a magnetic field generated according to the current flowing through the detected current path.

  In the conventional current sensor, when the through current Io flows through the detected electric wire W arranged at the center of the iron core F having a substantially C-shaped cross section with a gap GP formed in part as shown in FIG. Since the magnetic flux B proportional to the flowing through current Io is converged on the iron core F and penetrates the Hall element H inserted in the gap GP, a Hall voltage Vh is generated in the Hall element H due to the Hall effect. By detecting the Hall voltage Vh, the through current Io flowing through the detected electric wire W is detected.

  A current sensor for improving the conventional current sensor has been proposed. One of the conventional current sensor devices is a magnetic yoke Y partially having a gap G as shown in FIG. A current path I is disposed between the current path I and the gap G, and a magnetic field blocking section J for blocking a magnetic field generated by a magnetic flux that does not pass through the magnetic yoke Y is interposed between the current path I and the gap G. The magnetic sensor element S is disposed in G, and the current flowing through the current path I is measured by detecting the magnetic field in the gap G.

WO00-43795 Publication (Republication Publication)

  However, in the above-described conventional current sensor device, a current path I is disposed in a magnetic yoke Y partially having a gap G, and the magnetic yoke Y is passed between the current path I and the gap G. A magnetic field interrupting part J for interrupting a magnetic field due to no magnetic flux is inserted, and a magnetic sensor element S is disposed in the gap part G to detect the magnetic field in the gap part G. Since the current flowing through the path I is measured, it is difficult to place the current path I at an ideal position because of the necessity of inserting the magnetic field interrupting part J, and therefore, the current path I is disposed in the magnetic yoke Y. The position accuracy of the current path I and the position accuracy of the magnetic sensor element S disposed in the gap G affect the current measurement accuracy, and if the magnetic sensor element S fails for some reason, Measurement there is a problem that can not be.

  Therefore, the inventors of the present invention provide a current sensor that outputs a voltage signal corresponding to the current flowing through the detected current path from the magnitude of the magnetic field generated according to the current flowing through the detected current path. And a pair of magnetic yoke walls that are divided into two and arranged opposite to each other, are arranged in two air gaps arranged at symmetrical positions across the detected current path, and the air gap is From the magnitude of the magnetic field generated according to the current flowing through the detected current path by the two magnetic sensors whose direction along the wall surface of the pair of magnetic yoke walls facing each other is a magnetic sensitive direction, the detected current path The voltage signal corresponding to the current flowing through the current signal is processed, and signal processing is performed by the sum of the output voltage signals to detect the current flowing through the detected current path. As a result of further research and development after focusing on the idea, it is possible to cancel the influence of the positional deviation of the detected current path even if there is a positional deviation of the detected current path. In addition, the present invention achieves the object of achieving the object that even if one of the magnetic sensor elements fails for some reason, the other magnetic sensor element can measure current.

  Further, the present inventors provide a current sensor that outputs a voltage signal corresponding to a current flowing through the detected current path based on a magnitude of a magnetic field generated according to a current flowing through the detected current path. The magnetic yoke wall is enclosed in an annular shape so as to block the external magnetic field, and the pair of magnetic yoke walls that are divided into two inside the outer magnetic yoke wall are arranged at symmetrical positions across the detected current path. The detected current path is defined by the two magnetic sensors whose directions along the wall surfaces of the pair of magnetic yoke walls facing each other through the air gaps arranged in the two air gaps are in a magnetosensitive direction. A voltage signal corresponding to the current flowing through the detected current path is output from the magnitude of the magnetic field generated according to the flowing current, and the two magnetic sensors are output by the signal processing circuit. As a result of further research and development, focusing on the technical idea of the present invention that detects the current flowing through the detected current path by performing signal processing based on the sum of the voltage signals output from the sensor, measurement using an external magnetic field The purpose is that the influence on the measurement accuracy of the current is suppressed, and even if one of the magnetic sensor elements fails for some reason, the current can be measured by the other of the magnetic sensor elements. The present invention has been achieved.

The current sensor of the present invention (first invention according to claim 1) is:
In the current sensor that outputs a voltage signal corresponding to the current flowing through the detected current path from the magnitude of the magnetic field generated according to the current flowing through the detected current path,
A pair of magnetic yoke walls surrounding the detected current path in an annular shape and divided into two by two air gaps disposed at symmetrical positions across the detected current path;
A direction along the wall surfaces of the pair of magnetic yoke walls that are respectively disposed in the two air gaps and face each other through the air gap is a magnetic sensing direction, and corresponds to a current flowing through the detected current path. The detected current is calculated based on the sum of the two magnetic sensors output as voltage signals corresponding to the current flowing through the detected current path from the magnitude of the magnetic field generated by the current and the voltage signals output from the two magnetic sensors. A signal processing circuit that performs signal processing as a current flowing through the path is provided.

The current sensor of the present invention (the second invention according to claim 2) is:
In the first invention,
Outside the pair of magnetic yoke walls, an outer magnetic yoke wall that surrounds the detected current path in an annular shape and blocks an external magnetic field is provided.

The current sensor of the present invention (the third invention described in claim 3) is
In the second invention,
The signal processing circuit applies a reference current to the detected current path in advance, detects outputs from the two magnetic sensors, calculates correction coefficients for the respective sensor outputs in advance, and calculates the correction coefficients for the calculated sensor outputs. , The signal processing is performed so that the outputs from the two magnetic sensors coincide with each other.

The current sensor of the present invention (the fourth invention according to claim 4) is:
In the third invention,
An amorphous element in which the magnetic sensor is made of an amorphous wire disposed at a position where the linear relationship of the output in the magnetic field generated by the current flowing through the detected current path is maintained, and the internal magnetic field changes corresponding to the surrounding magnetic field When,
It is composed of a detection coil that forms a magneto-inductive magnetic detector by being wound around the amorphous element and converting a change in the internal magnetic field of the amorphous element into a voltage by electromagnetic induction.

The current sensor of the present invention (the fifth invention according to claim 5) is:
In the fourth invention,
The outer magnetic yoke wall and the inner pair of magnetic yoke walls have a hollow rectangular cross-sectional shape.

The current sensor of the present invention (the sixth invention according to claim 6) is:
In the fifth invention,
A sensor main body including the outer magnetic yoke wall and the inner magnetic yoke wall is built in a wall surface of a casing in which the detected current path is disposed.

  The current sensor of the first invention configured as described above is a current sensor that outputs a voltage signal corresponding to the current flowing through the detected current path from the magnitude of the magnetic field generated according to the current flowing through the detected current path. Surrounding the detection current path in an annular shape and being arranged in two air gaps arranged in symmetrical positions across the detected current path of a pair of magnetic yoke walls that are divided and arranged in two parts, From the magnitude of the magnetic field generated according to the current flowing through the detected current path by the two magnetic sensors whose direction along the wall surface of the pair of magnetic yoke walls facing each other through the air gap is a magnetic sensitive direction. The detected current path is output as a voltage signal corresponding to the current flowing through the detected current path, and is subjected to signal processing by the sum of the output voltage signals applied by the signal processing. Therefore, even if there is a misalignment of the detected current path, it is possible to cancel the influence of the misalignment of the detected current path, so that the measurement accuracy of the current flowing through the detected current path is affected. In addition, there is an effect that even if one of the magnetic sensors fails for some reason, current can be measured by the other of the magnetic sensors.

  In the current sensor of the second invention configured as described above, the external magnetic field is blocked by the outer magnetic yoke wall that annularly surrounds the detected current path outside the pair of magnetic yaw 6 walls in the first invention. As a result, the measurement accuracy of the current flowing through the detected current path is improved.

  In the current sensor of the third invention configured as described above, in the second invention, the signal processing circuit sends a reference current to the detected current path in advance and detects outputs from the two magnetic sensors. The signal processing is performed so that the outputs from the two magnetic sensors coincide with each other by obtaining the correction coefficients of the respective sensor outputs in advance and referring to the obtained correction coefficients of the sensor outputs. There is an effect of increasing the measurement accuracy of the current flowing through the.

  The current sensor according to the fourth aspect of the present invention configured as described above is disposed at a position where the linear relationship of the output in the magnetic field generated by the current flowing through the detected current path constituting the magnetic sensor is maintained in the third aspect. Since the internal magnetic field of the amorphous element made of the amorphous wire changes corresponding to the surrounding magnetic field, the amorphous element is formed by the detection coil constituting the magneto-inductive magnetic detector wound around the amorphous element. The internal magnetic field change is converted to voltage by electromagnetic induction, so the stability against temperature change is improved, and it can be used to prevent deterioration of measurement accuracy under the environment where large temperature change such as car, for example, There is an effect of preventing high costs.

  In the current sensor of the fifth invention configured as described above, in the fourth invention, since the outer magnetic yoke wall and the pair of inner magnetic yoke walls have a hollow rectangular cross-sectional shape, the size of the sensor can be reduced. The effect of making it possible.

  In the current sensor of the sixth invention configured as described above, in the fifth invention, the sensor main body including the outer magnetic yoke wall and the inner magnetic yoke wall is disposed on a wall surface of the casing in which the detected current path is disposed. Since it is built in, there is an effect that it is not necessary to secure a space for arranging the sensor.

It is sectional drawing which shows the current sensor of 1st Example of this invention. It is a perspective view for demonstrating the detection principle of the magnetic sensor which comprises this 1st Example. It is a side view for demonstrating the detection principle of the magnetic sensor of a 1st Example. It is a circuit diagram which shows the electric circuit of the magnetic sensor of a 1st Example. It is a diagram which shows the relationship between the magnitude | size and output of a magnetic field in the magnetic sensor of a 1st Example. It is a diagram which shows the temperature characteristic of the output of the magnetic detector using the electromagnetic induction in the magnetic sensor of the 1st Example. It is a perspective view for demonstrating the detection principle of the magnetic sensor arrange | positioned in a pair of air gap which comprises the 1st Example. It is a side view for demonstrating the detection principle of a pair of magnetic sensor of the 1st Example. It is sectional drawing which shows the current sensor of 2nd Example of this invention. It is explanatory drawing for demonstrating the dimension relationship of each part of the magnetic sensor in a 2nd Example. It is sectional drawing which shows the aspect which has arrange | positioned the current sensor of the 2nd Example to the inverter unit for motor vehicles. It is sectional drawing which follows the AA line in FIG. 11 which shows the aspect which has arrange | positioned the current sensor of the 2nd Example to the inverter unit for motor vehicles. It is a perspective view which shows one magnetic sensor of the 2nd Example. It is a diagram for demonstrating the influence of position shift in the magnetic sensor of the 2nd Example. It is a diagram for demonstrating the linearity (0.2% * FS) in the magnetic sensor of the 2nd Example, and the linearity by yoke design. It is a diagram for explaining the effect of temperature correction in the magnetic sensor of the second embodiment and the relationship between the external magnetic field and output voltage at different temperatures. It is a diagram for demonstrating the influence of the other phase in the magnetic sensor of the 2nd Example. It is sectional drawing which shows the current sensor of the modification of this invention. It is a perspective view which shows the conventional current sensor. It is sectional drawing which shows the conventional current sensor apparatus.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS The best mode for carrying out the invention will be described below with reference to the accompanying drawings.

  The current sensor according to the first embodiment has a voltage corresponding to the current flowing through the detected current path 1 based on the magnitude of the magnetic field generated according to the current flowing through the detected current path 1 as shown in FIGS. In the current sensor that outputs a signal, the detected current path 1 is annularly surrounded and divided into two by two air gaps 23 and 24 that are arranged symmetrically with respect to the detected current path 1. A direction along the wall surfaces of the pair of magnetic yoke walls 21, 22 opposed to each other and the two air gaps 23, 24 respectively opposed to each other via the air gap. Two magnetic sensors 31 and 3 that output as voltage signals corresponding to the current flowing through the detected current path 1 from the magnitude of the magnetic field generated in accordance with the current flowing through the detected current path in the direction of magnetic sensing. By the sum of bets and the voltage signal output from the two magnetic sensors, the one in which is provided a signal processing circuit 6 to the signal processing as a current flowing through the detection current path 1.

  The pair of magnetic yoke walls is hollow by arranging the yoke walls 21 and 22 having a U-shaped cross section facing each other via two air gaps 23 and 24 in the sensor body 100. It forms a rectangular cross-sectional shape.

  The sensor main body 100 is constituted by a rectangular main body larger than the pair of magnetic yoke walls, and a slit-like opening 101 for inserting a bus bar as the detected current path 1 is formed in parallel with the center portion. Has been.

  As shown in FIG. 2, the magnetic sensors 31 and 32 are positions where the linear relationship of the output in the magnetic field generated by the current flowing through the detected current path 1 is maintained and within a predetermined magnetic field magnitude range. The amorphous element 30 is made of an amorphous wire having a diameter of 30 μm and a length of 3 mm or less arranged in parallel with the direction of the magnetic field, and the internal magnetic field changes in response to the surrounding magnetic field due to the detected current. The coil is wound to convert the change in the internal magnetic field of the amorphous element into a voltage by electromagnetic induction, so that the magneto-inductive magnetic detector 20 and the voltage of the detection coil correspond to the current flowing through the detected wire. It comprises a signal conversion circuit 5 for converting it into a voltage signal.

  As shown in FIG. 2, the current sensor 2 of the first embodiment includes an amorphous wire 30 around which the detection coil 4 disposed above the current path 1 as the detected electric wire 10 made of a conductor is wound, and It comprises the signal conversion circuit 5 connected to the detection coil 4, and constitutes a magneto-inductive magnetic detector 20 that converts the internal magnetic field change of the amorphous element 3 into a voltage by electromagnetic induction by the detection coil 4. .

  As shown in FIG. 3, the magnetic field B1 generated by the current flowing in the current path as the detected electric wire 10 to be measured generates a circular magnetic field according to the right-handed screw law, and the magnitude thereof is a distance L from the current path. Although inversely proportional to the above, the amorphous wire 30 is disposed above the distance L directly above the current path as the detected electric wire 10.

  In the magneto-inductive magnetic detector 20, when the magnitude of the input magnetic field is excessive, as in a normal magnetic sensor, the output voltage is saturated and the linear relationship between the input and output is lost as shown in FIG. Therefore, in the first embodiment, the magneto-inductive magnetic detector 20 is disposed at a predetermined position where the magnitude of the magnetic field is within a linear range in which the amorphous wire 30 is not saturated.

  FIG. 4 shows an electric circuit 200 in the current sensor 2 of the first embodiment, which comprises the current path 1 and a magneto-inductive magnetic detector 20. The current path 1 as the detected electric wire 10 is for flowing a current to be measured, and the magnetic field generated by this current gives the amorphous wire 30 an internal magnetic field change.

  In the electric circuit 200, the pulse generator 210 outputs synchronized pulses of P1, P2, and P3 to the amorphous wire 30, the analog switch S221 of the detection circuit 220, and the analog switch S251 of the excitation circuit 250, respectively. These three pulses are preceded by P3, followed by P1 and P2, and are repeated at a frequency of 1 MHz, for example, so that the magnetic field is measured at a frequency of 1 MHz.

  When the pulse P3 is generated, the analog switch S251 of the excitation circuit 250 is momentarily closed, and an excitation current flows from the power source VD through the resistor R251 to the detection coil 4 wound around the amorphous wire 30, and the amorphous wire 30 is temporarily energized and initialized.

  When the flow of the excitation current ends and a pulse P1 is generated after a predetermined time and the pulse current P1 is applied to the amorphous wire 30, the amorphous wire 30 corresponds to the pulse current P1 and the peripheral magnetic field where the amorphous wire is placed. As a result, an internal magnetic field change occurs. At this time, a voltage corresponding to the change in the internal magnetic field is generated at the terminal of the detection coil 4 due to electromagnetic induction.

  This voltage is held in the capacitor C221 of the sample hold circuit by momentarily closing the analog switch S221 of the detection circuit 220 constituting the signal conversion circuit 5 constituting the signal processing circuit 6. The amplifier 230 composed of an operational amplifier amplifies the voltage of the detection circuit 220 and outputs a voltage signal corresponding to the current to be measured to the output terminal.

  Here, the role of the excitation circuit 250 will be described. In FIG. 5, when a magnetic field that is stronger than the magnetic field due to the measurement current and causes noise saturation of the amorphous wire 30 or noise above the S1 level is applied to the N pole due to the hysteresis characteristics of the amorphous wire 30 When the magnetic field is saturated at the S pole, the operation lines after the magnetic fields are removed are different from each other by n1 and s1, and a slight offset error occurs. Therefore, immediately before each measurement repeated at a frequency of 1 MHz, the excitation circuit 250 initializes with a predetermined excitation current, and the operation line is always the same (for example, s1 is always used) to eliminate the hysteresis error.

  As described above, since the current sensor of the first embodiment is composed of the magneto-inductive magnetic detector 20, the output characteristics do not change with respect to a wide range of temperature changes as shown in FIG. Therefore, it is possible to realize a current sensor that can measure current with high stability and high accuracy even in a severe temperature environment such as an automobile.

  As described above, in the current sensor of the first embodiment, the change in the internal magnetic field generated in the amorphous wire 30 in response to the magnetic field generated by the current flowing through the current path 1 as the detected electric wire 10 is described above. The detection coil 4 wound around the amorphous wire 30 detects the voltage by electromagnetic induction, and holds it in a capacitor C221 as a sample hold circuit by turning on and off the analog switch of the detection circuit 220.

  The two magneto-inductive magnetic detectors 20 are respectively disposed in a pair of magnetic yoke walls 21 and 22 arranged opposite to each other as shown in FIGS. 1 and 8 and the two air gaps 23 and 24. Since the magnetic field B1 due to the current is circular as shown in the sectional view from the axial direction of the current path 1, the sensitivity direction of the amorphous wire 30 is the same as shown by the arrow, and the current path 1 is sandwiched, for example. Thus, the magnetic field directions of the measurement currents flowing in the current path 1 are arranged so as to be opposite to each other.

  The signal processing circuit 6 supplies a plurality of reference currents covering the measurement range to the detected current path in advance, detects outputs from the two magnetic sensors 31 and 32, and corrects the respective sensor output correction coefficients. Is obtained in advance, and signal processing is performed so that the outputs from the two magnetic sensors coincide with each other by referring to the obtained correction coefficient of the sensor output.

  At this time, in the signal processing circuit 6, the magnetic field signals measured by the two magneto-inductive magnetic detectors 20 are separated into positive and negative signs. On the other hand, components such as geomagnetism that cause noise have the same sign. Accordingly, the output signals of the two magneto-inductive magnetic detectors are differentially operated by the differential amplifier 62. Therefore, if the difference between the output terminals 63 of the differential amplifier 62 is calculated, the signal of the magnetic field due to the current to be measured is added. It becomes sum, and noise due to geomagnetism is canceled out and can be made zero.

  The current sensor of the first embodiment uses two magneto-inductive magnetic detectors 20 as shown in FIG. 7, and the detection directions are the same and the directions of the magnetic fields generated by the measurement currents are opposite to each other. And a differential amplifier 62 for calculating the difference between the output signals of the two magneto-inductive magnetic detectors 20 at a predetermined point symmetrical with respect to the current path 1. It eliminates the effects of noise components such as geomagnetism and enables high-precision current measurement.

  In the current sensor of the first embodiment, since the two output signals are differentially calculated by the differential amplifier 63, noise due to geomagnetism or the like can be canceled out to zero, so that there is no noise mixing. The effect of enabling accurate current measurement is achieved.

  Further, in the first embodiment, an internal magnetic field change generated in the amorphous wire 30 is detected as a voltage by an electromagnetic induction action by the detection coil 4 wound around the amorphous wire 30. As for the magnetic characteristics of the change in the internal magnetic field of the amorphous element, the temperature output characteristics are very stable below the vitrification temperature at which the amorphous structure is maintained, and the electromagnetic induction action by the detection coil 4 is also resistant to temperature changes. stable. On the other hand, in a current sensor that directly detects the voltage at both ends of a conventional magnetic impedance element, a change in impedance of the magnetic impedance element is detected as a voltage at both ends. Since it has a temperature characteristic that the output changes with respect to the temperature change, the voltage across the magneto-impedance element changes due to the temperature change. Therefore, the current sensor of the first embodiment is superior in output stability with respect to temperature change in this respect as compared with the conventional one.

  In the first embodiment, the voltage detected by the detection coil 4 due to electromagnetic induction action is held in the capacitor C221 as a sample and hold circuit by turning on and off the analog switch of the detection circuit 220. Compared to a conventional sensor using a diode having a temperature characteristic in the forward voltage as a detection circuit, the output stability is excellent with respect to a temperature change.

  Furthermore, the current sensor of the first embodiment is a current sensor 3 that outputs a voltage signal corresponding to the current flowing through the detected current path 1 from the magnitude of the magnetic field generated according to the current flowing through the detected current path 1. The two magnetic sensors 31 and 32 surround the detected current path 1 in an annular shape, and are symmetrical with respect to the detected current path of a pair of magnetic yoke walls 21 and 22 that are divided and arranged opposite to each other. The two magnetic sensors 31 disposed in the two air gaps disposed at positions, and the direction along the wall surfaces of the pair of magnetic yoke walls facing each other through the air gap is a magnetosensitive direction; 32 is output as a voltage signal corresponding to the current flowing through the detected current path from the magnitude of the magnetic field generated according to the current flowing through the detected current path 1, and is output by the signal processing. Since the signal processing is performed based on the sum of the detected voltage signals and the current flowing through the detected current path is detected, the positional deviation of the detected current path 1 is detected even if the detected current path 1 is misaligned. The influence of the current flowing through the detected current path on the measurement accuracy is suppressed, and even if one of the magnetic sensors 31 and 32 fails for some reason, the magnetic sensor element The other effect is that current can be measured.

  Further, in the current sensor of the first embodiment, the inner pair of magnetic yoke walls 21 and 22 is formed of a 1.5 mmt (thickness) non-oriented silicon steel plate as shown in FIG. 1 and FIG. As a hollow rectangular cross section, that is, each of which has a U-shaped cross section and corrects and absorbs mounting errors (0.5 mm on the left and right, 0.5 mm on the top and bottom). .

  As shown in FIGS. 9 to 13, the current sensor of the second embodiment surrounds the detected current path 1 annularly outside the pair of magnetic yoke walls 21 and 22 in the first embodiment described above. The main difference is that the outer magnetic yoke wall 25 for blocking the external magnetic field is added, but the difference will be mainly described below.

  The current sensor according to the second embodiment is an example in which the present invention is applied to a current sensor for detecting a current from 0 A to 700 A flowing through a bus bar of an automobile inverter.

  As shown in FIG. 9, the outer magnetic yoke wall 25 has a hollow rectangular cross-sectional shape, that is, a substantially square-shaped cross-sectional shape with a long side of 23 mm and a short side. Has a length of 12 (or 11.2) mm and blocks an external magnetic field.

  The inner pair of magnetic yoke walls 21 and 22 are made of a 1.5 mmt (thickness) non-oriented silicon steel plate as shown in FIG. 10, and have a hollow rectangular cross-sectional shape as a whole. Each has a substantially U-shaped cross-sectional shape for correcting and absorbing mounting errors (0.5 mm on the left and right, 0.5 mm on the top and bottom).

  That is, as shown in FIG. 10, the distance between the inner wall of the outer magnetic yoke wall 25 and the outer walls of the pair of inner magnetic yoke walls 21 and 22 is 1 mm, and the pair of inner magnetic yoke walls 21 and 22. The distance between the inner wall of the slit and the slit-shaped opening 101 formed in parallel to the central portion for inserting the bus bar as the detected current path 1 is 1 mm, and the pair of inner magnetic yokes The gap between the opposed ends 211 and 221 of the walls 21 and 22 is 3 mm, and the cross-sectional shape of the inner wall of the outer magnetic yoke wall 25 and the pair of inner magnetic yoke walls 21 and 22 is the current path 1 to be detected. It has a shape corresponding to the cross-sectional shape of the bus bar.

  A sensor body 100 made of, for example, a non-magnetic heat-resistant synthetic resin including the outer magnetic yoke wall 25 and the inner magnetic yoke walls 21 and 22 is a wall surface of a casing of an automotive inverter unit in which the detected current path is disposed. It is built in.

  That is, as shown in FIG. 12, the left and right bus bars 101 and 102 of the three bus bars arranged in parallel vertically at a pitch of 23 mm on the wall surface of the casing of the inverter unit for an automobile are the inside and outside in the second embodiment. It is inserted into a slit-like opening 101 provided in the center of the current sensor 3 shown in FIG.

  As shown in FIG. 12, the bus bar 103 at the center of the wall surface has a long side of 13 mm provided at the center of the current sensor having the pair of inner magnetic yoke walls 21 and 22 described in the first embodiment. The short side is inserted into the slit-like opening 101 of 1.2 mm.

  The current sensor of the second embodiment configured as described above outputs a voltage signal corresponding to the current flowing through the detected current path 1 from the magnitude of the magnetic field generated according to the current flowing through the detected current path 1. The two magnetic sensors 31 and 32 as the sensors 3 surround the detected current path 1 in an annular shape, and the detected current paths of a pair of magnetic yoke walls 21 and 22 that are divided and arranged opposite to each other. The two air gaps arranged at symmetrical positions on both sides, and the direction along the wall surfaces of the pair of magnetic yoke walls facing each other through the air gap is the magnetic sensitive direction. The magnetic sensors 31 and 32 output a voltage signal corresponding to the current flowing through the detected current path from the magnitude of the magnetic field generated according to the current flowing through the detected current path 1, and the signal processing circuit 6 Therefore, since the signal processing is performed by the sum of the output voltage signals and the current flowing through the detected current path is detected, the detected current path 1 is detected even if the detected current path 1 is misaligned. Therefore, even if one of the magnetic sensors 31 and 32 breaks down for some reason, the magnetic force can be reduced. There is an effect that the current can be measured by the other sensor element.

  In the current sensor of the second embodiment, an external magnetic field is interrupted by the outer magnetic yoke wall 25 that annularly surrounds the detected current path outside the pair of magnetic yoke walls 21 and 22. There is an effect of increasing the measurement accuracy of the current flowing through the detection current path 1.

  That is, in the current sensor of the second embodiment, the output linearity is shown in FIG. 15A with the external magnetic field on the horizontal axis and the output linearity (0.2% · FS) on the vertical axis. When the output from the magnetic sensor when the external magnetic field changes is displayed, the change in the output from the magnetic sensor is suppressed to a very small 0.24% FS (typ.) Even if the external magnetic field changes. There is an effect that it has been.

  In the current sensor of the second embodiment, the pair of inner magnetic yoke walls 21 and 22 are made of a 1.5 mmt (thickness) non-oriented silicon steel plate as shown in FIG. In other words, each of the detected current paths 1 is mounted in the slit-shaped opening 101 with respect to the magnetic yoke walls 21 and 22, each having a U-shaped cross-sectional shape. An error (0.5 mm on the left and right, 0.5 mm on the top and bottom) is corrected and absorbed.

  That is, in the current sensor of the second embodiment, the detected current path 1 inserted into the slit-shaped opening 101 with respect to the magnetic yoke walls 21 and 22 is shifted 0.5 mm upward and 0.5 mm right. The detection output in this case is almost zero regardless of the magnitude of the detected current as shown in FIG. 14 where the horizontal axis represents the current and the vertical axis represents the influence (%) of the deviation.

  Further, in the current sensor of the second embodiment, the signal processing circuit 6 applies a reference current to the detected current path 1 in advance before shipment, and detects the outputs from the two magnetic sensors 31 and 32. Each sensor output correction coefficient is obtained in advance, the obtained sensor output correction coefficient is stored in a memory, and the stored correction coefficients are referenced so that the outputs from the two magnetic sensors match. Therefore, the measurement accuracy of the current flowing through the detected current path is improved.

That is, in the current sensor of the second embodiment, when the current flowing through the detected current path 1 increases by referring to the yoke design of the magnetic yoke walls 21 and 22 and the correction coefficient, the detected current path 1 is Since the generated magnetic field increases in accordance with the increase in the flowing current, the sum Bx1 + Bx2 (G) of the magnetic fields detected in accordance with the increase in the current is linear (R ² = 0. The linearity is ensured by the yoke design, and the MI sensor itself is good.

  Further, the current sensor according to the second embodiment is characterized in that the amorphous element comprising an amorphous wire disposed at a position where the linear relationship of the output in the magnetic field generated by the current flowing through the detected current path constituting the magnetic sensor is maintained. However, since the internal magnetic field changes in response to the surrounding magnetic field, the change in the internal magnetic field of the amorphous element 30 is made electromagnetic by the detection coil 4 constituting the magneto-inductive magnetic detector 20 wound around the amorphous element. Since it is converted into voltage by induction, it improves stability against temperature changes, and can be used by preventing deterioration of measurement accuracy in environments where large temperature changes occur, such as automobiles, thereby preventing high costs. There is an effect.

  That is, when the output voltage of the two magnetic sensors 31 and 32 when the external magnetic field (G) changes in a state where the ambient temperature is different when the current sensor of the second embodiment is different, for example, At 150 ° C., the output characteristics change as shown in FIG. 16B. Therefore, in the temperature range of −20 ° C. to 85 ° C., the ambient temperature of the sensor is previously set to −20 ° C. to 85 ° C. before shipment. The temperature of each of the two magnetic sensors 31 and 32 is measured by setting each temperature within the range, the temperature correction coefficient of each sensor output is obtained in advance, and the obtained temperature correction coefficient of the sensor output is stored in the memory. Since signal processing is performed so that the temperature is corrected by canceling the temperature change from the outputs from the two magnetic sensors by referring to the stored temperature correction coefficient. The output from the current sensor in the Y-phase and Z-phase is not almost changed even if the temperature changes as shown in FIG. 16 (A).

  Furthermore, in the current sensor of the second embodiment, since the outer magnetic yoke wall 25 and the pair of inner magnetic yoke walls 21 and 22 have a hollow rectangular cross section, it is possible to reduce the size of the sensor. There is an effect.

  In the current sensor of the second embodiment, the sensor main body including the outer magnetic yoke wall 25 and the inner magnetic yoke walls 21 and 22 is built in the wall surface of the casing in which the detected current path is disposed. There is an effect that it is not necessary to secure a space for arranging the sensor.

  Furthermore, the current sensor according to the second embodiment includes the adjacent bus bar 102 or the adjacent bus bar 102 in one phase surrounded by the outer magnetic yoke wall 25 with the bus bar 101 through which +600 A current flows among the three adjacent phases in FIG. It was examined whether or not it was affected by other phases by measuring in a state where a current of −300 A flows in the other phase of 103 (there is a neighboring phase) and 0 A, that is, a state where no current is flowing (no neighboring phase). As shown in FIG. 17, it was confirmed that the influence of the adjacent current in the external yoke was almost zero, and there was no difference in the detection output.

  The above-described embodiments are illustrated from the viewpoint of easy implementation, which is a requirement of the law, and the present invention is not limited thereto. Based on the claims, the detailed description of the invention, and the drawings, Modifications and additions can be made without departing from the technical idea of the present invention that can be recognized by those skilled in the art.

  In the above-described embodiment, the detected current path is an elongated rectangular bus bar, and the outer magnetic yoke wall 25 and a pair of inner magnetic yokes are provided from the viewpoint of being built in the wall surface of the casing of the inverter unit for an automobile. Although the current sensor has been described in which the walls 21 and 22 have an elongated hollow rectangular cross-sectional shape, the present invention is not limited to these, and is applied to a square-shaped current sensor with little difference in vertical and horizontal dimensions. Is possible.

  Further, according to the present invention, when the detected current path 1C has a circular cross section regardless of the diameter, as shown in FIG. 18, the outer magnetic yoke wall 25C and a pair of inner magnetic yoke walls 21C and 22C are provided. Is a current sensor having a double hollow circular cross-sectional shape and two magnetic sensors 31C and 32C interposed in gaps 23C and 24C between the pair of inner magnetic yoke walls 21C and 22C. It is possible to apply to.

  Further, in the above-described embodiment, the electric wire arrangement position as the detected current path is arranged at the substantially central portion in the yoke as the shield, and the sectional shape of the magnetic shield is rectangular. The invention is not limited to these, but can be changed to a petal shape having an irregular shape such as an ellipse, an oval, a wavy shape, a polygon, or any other cross-sectional shape depending on the magnitude of the current to be measured and the shape required for the current sensor In addition, the position of the detected electric wire in the shield is not limited to the center and the center, and may be disposed at a position deviated from the center or a position close to the periphery as necessary.

  Further, in the above-described embodiment, the application of the automobile is illustrated and described as an example of the application used under a severe temperature environment. However, the present invention is not limited thereto, and the automobile is used as necessary. It can be applied to other uses such as ships, aircrafts, factories, offices, homes, etc.

  In the present invention, each of the currents flowing through the plurality of wires as the detected current path has a predetermined value for the strength of the magnetic field applied to the magneto-inductive magnetic detector. Enables the magnet-inductive magnetic detector to be stably disposed at a predetermined distance from the magnet-inductive magnetic detector, and the magnet-inductive magnetic detector accommodated in the package or yoke as the current increases. The distance between the wires needs to be large.

  In the above-described embodiment, the sensor body 100 made of, for example, a non-magnetic heat-resistant synthetic resin including the outer magnetic yoke wall 25 and the inner magnetic yoke walls 21 and 22 is used for an automobile in which the detected current path is disposed. Although examples of being incorporated in the wall surface of the casing of the inverter unit have been illustrated, the present invention is not limited thereto, and the sensor main body 100 including the outer magnetic yoke wall 25 and the inner magnetic yoke walls 21 and 22 includes As long as it is a non-magnetic material, an inorganic material other than a heat-resistant synthetic resin, such as a ceramic material, can be used.

  In a current sensor that outputs a voltage signal corresponding to the current flowing through the detected current path from the magnitude of the magnetic field generated according to the current flowing through the detected current path, the detected current path is annularly surrounded to provide an external magnetic field. A pair of magnetic yokes which are divided into two by an outer magnetic yoke wall to be cut off and two air gaps arranged at symmetrical positions inside the outer magnetic yoke wall 25 across the detected current path A direction along the wall surfaces of the pair of magnetic yoke walls that are respectively disposed in the wall and the two air gaps and face each other through the air gap is a magnetosensitive direction and flows through the detected current path. Two magnetic sensors output as voltage signals corresponding to the current flowing through the detected current path 1 based on the magnitude of the magnetic field generated according to the current, and the two magnetic sensors. A signal processing circuit that performs signal processing as a current flowing through the detected current path 1 based on the sum of the voltage signals is suppressed, and the influence on the current measurement accuracy is suppressed, and one of the magnetic sensor elements has failed for some reason. Further, the present invention can be applied to an application in which current can be measured by the other of the magnetic sensor elements.

DESCRIPTION OF SYMBOLS 1 Detected current path 21, 22 Magnetic yoke wall 25 Outer magnetic yoke wall 23, 24 Air gap 31, 32 Magnetic sensor 6 Signal processing circuit

Claims (6)

In the current sensor that outputs a voltage signal corresponding to the current flowing through the detected current path from the magnitude of the magnetic field generated according to the current flowing through the detected current path,
A pair of magnetic yoke walls surrounding the detected current path in an annular shape and divided into two by two air gaps disposed at symmetrical positions across the detected current path;
A direction along the wall surfaces of the pair of magnetic yoke walls that are respectively disposed in the two air gaps and face each other through the air gap is a magnetic sensing direction, and corresponds to a current flowing through the detected current path. The detected current by the sum of two magnetic sensors that output as voltage signals corresponding to the current flowing through the detected current path from the magnitude of the generated magnetic field, and the voltage signals output from the two magnetic sensors. A current sensor comprising a signal processing circuit that performs signal processing as a current flowing through a path. In claim 1,
A current sensor comprising an outer magnetic yoke wall that annularly surrounds the detected current path and blocks an external magnetic field outside the pair of magnetic yoke walls. In claim 2,
The signal processing circuit applies a reference current to the detected current path in advance, detects outputs from the two magnetic sensors, calculates correction coefficients for the respective sensor outputs in advance, and calculates the correction coefficients for the calculated sensor outputs. The current sensor is configured to perform signal processing so that outputs from the two magnetic sensors coincide with each other by referring to FIG. In claim 3,
An amorphous element in which the magnetic sensor is made of an amorphous wire disposed at a position where the linear relationship of the output in the magnetic field generated by the current flowing through the detected current path is maintained, and the internal magnetic field changes corresponding to the surrounding magnetic field When,
A current sensor comprising a detection coil which forms a magneto-inductive magnetic detector by being wound around the amorphous element and converting an internal magnetic field change of the amorphous element into a voltage by electromagnetic induction. In claim 4,
The current sensor, wherein the outer magnetic yoke wall and the inner pair of magnetic yoke walls have a hollow rectangular cross section. In claim 5,
A current sensor, wherein a sensor body including the outer magnetic yoke wall and the inner magnetic yoke wall is built in a wall surface of a casing in which the detected current path is disposed.

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