JP2011027530A - Current detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current detector reducing the influence of a displacement even when a relative position between a conductive member and a magnetic sensor is displaced so as to rotate. <P>SOLUTION: A first magnetic sensor 20 is arranged inside a first loop section 12, such that its magnetism detection direction matches with a direction of a magnetic field generated by current flowing through the first loop section 12, and a second magnetic sensor 21 is arranged inside a second loop section 13, such that its magnetism detection direction matches with a direction of a magnetic field generated by current flowing through the second loop section 13. Provided are: a magnetism computing means 41, which computes a magnetism value generated by current flowing through a bus bar 10 on the basis of a difference between outputs of the first magnetic sensor 20 and the second magnetic sensor 21; and a current computing means 42, which computes the current flowing through the bus bar 10 on the basis of the magnetism value computed by the magnetism computing means 41. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a current detection device that detects a current flowing through a conductor using a magnetic sensor.

  Conventionally, a conductor is passed through a core provided so as to form a closed magnetic circuit including an air gap, and a magnetic sensor disposed in the gap detects a magnetism generated by a current flowing through the conductor, and a current flowing through the conductor. There is known a current detection device that seeks for (see, for example, Patent Document 1).

  According to the current detection device described in Patent Document 1, the magnetism generated by the current flowing through the conductor can be concentrated on the core, so that the magnetism detection sensitivity can be increased. However, the provision of the core increases the cost of the components and has the disadvantage of increasing the space for mounting the components to provide the core. Furthermore, there is a disadvantage that the current detection accuracy deteriorates due to the influence of the temperature change of the core.

  Therefore, a current detection device has been proposed in which magnetism generated by a current flowing through a conductor is detected by a magnetic sensor without using a core to obtain a current (see, for example, Patent Document 2).

  In Patent Document 2, as shown in FIG. 7A, Hall elements 91 and 92 are formed at locations where two rectangular shapes (90a, 90b, 90c and 90c, 90d, 90e) of the conductive member 90 are formed. Is described so that the magnetic field from three directions generated by the current flowing through the conducting member 90 passes through the Hall elements 91 and 92 to increase the sensitivity of magnetic detection. In this configuration, the influence of external noise is reduced by averaging the detection signals of the Hall elements 91 and 92.

JP 2005-308635 A JP 2007-183221 A

  In the case of the configuration of FIG. 7A described above, as shown in FIG. 7B, when the relative position between the conductive member 90 and the Hall elements 91 and 92 is shifted in the horizontal direction in the drawing, the Hall element 91 is obtained. For, the magnetic field generated by the current Ic flowing through 90c becomes stronger, while the magnetic field generated by the current Ie flowing through 90e becomes weaker. In the Hall element 92, the magnetic field generated by the current Ia flowing through 90a becomes strong, while the magnetic field generated by the current Ic flowing through 90c becomes weak. For this reason, the intensity of the magnetic field detected by the Hall elements 91 and 92 hardly changes, and the influence of the positional deviation is slight.

  Further, as shown in FIG. 7C, when the relative position between the conducting member 90 and the Hall elements 91 and 92 is shifted in the vertical direction, the magnetic field generated by the current Id flowing through 90d is detected for the Hall element 91. Since the minute becomes larger, the detected magnetic field becomes stronger. On the other hand, with respect to the Hall element 92, the detected magnetic field generated by the current Ib flowing through 90b becomes small, and the detected magnetic field becomes weak. Therefore, by averaging the magnetic fields detected by the Hall elements 91 and 92, it is possible to reduce the influence of the positional deviation in the vertical direction.

  However, as shown in FIG. 7D, when the relative position between the conducting member 90 and the Hall elements 91 and 92 is shifted in the rotation direction, the magnetic field generated by the current Ic flowing through the 90c is detected for the Hall element 91. Since both the minute and the detected amount due to the current Id flowing through 90d increase, the detected magnetic field becomes stronger.

  On the other hand, in the Hall element 92, both the detected amount of the magnetic field generated by the current Ia flowing through 90a and the detected amount of the magnetic field generated by the current Ib flowing through 90b increase, and the detected magnetic field becomes stronger. Therefore, even if the magnetic fields detected by the Hall elements 91 and 92 are averaged, the influence of the positional deviation cannot be reduced.

  Therefore, an object of the present invention is to provide a current detection device that can reduce the influence of positional deviation even when the relative position between the conducting member and the magnetic sensor is displaced in the rotational direction.

  The present invention has been made to achieve the above object, and detects the magnetism generated by the current flowing in the conductor by the first magnetic sensor and the second magnetic sensor without using the core for converging the magnetic flux. The present invention relates to a current detection device for obtaining the current.

The conductor includes a first loop portion in which the detected current flows in a first direction in the circumferential direction, and a second loop portion in which the detected current flows in a direction opposite to the first direction in the circumferential direction. The first magnetic sensor is disposed on the inner side of the first loop portion so that the direction of magnetic detection is aligned with the direction of the magnetic field generated by the current flowing through the first loop portion, and the second magnetic sensor is The magnetism detection direction is arranged inside the second loop portion so that the direction of magnetic detection is aligned with the direction of the magnetic field generated by the current flowing through the second loop portion, and the magnetic detection generated by the current flowing through the first loop portion of the first magnetic sensor. When the detection polarity and the detection polarity of the magnetism generated by the current flowing through the second loop portion of the second magnetic sensor are the same, and the first magnetic sensor and the second magnetic sensor are disposed, 1 Magnetic sensor Based on the difference between the outputs of the second magnetic sensor, the magnetism generated by the current flowing through the conductor is calculated, the detection polarity of the magnetism generated by the current flowing through the first loop portion of the first magnetic sensor, and the second When the magnetic sensor is arranged with the polarity detected by the current flowing through the second loop portion of the magnetic sensor reversed, it flows through the conductor based on the sum of the outputs of the first magnetic sensor and the second magnetic sensor. Magnetic calculation means for calculating magnetism generated by current, and current calculation means for calculating current flowing through the conductor based on the magnetism calculated by the magnetism calculation means.
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  According to the present invention, the magnetic field generated by the current flowing through the first loop portion is concentrated in the first loop (magnetization effect). Similarly, the magnetic field generated by the current flowing through the second loop portion is concentrated in the second loop. The magnetic field strength in the first loop and the second loop is made uniform.

  Therefore, even if the relative positions of the first loop portion and the second loop portion of the conductor and the first magnetic sensor and the second magnetic sensor are shifted so as to rotate, this shift is not caused by the first loop portion. If it is within the second loop portion, the influence of the positional deviation can be reduced, and the magnetism generated by the current flowing through the conductor can be calculated by the magnetism calculating means. The current calculation means can calculate the current flowing through the conductor based on the magnetism calculated by the magnetism calculation means.

  Further, the first loop portion and the second loop portion are formed by an upper surface member and a lower surface member arranged in parallel with an interval in a predetermined direction, and the first magnetic sensor and the second magnetic sensor are It is arranged between the upper surface member and the lower surface member.

  According to the present invention, when the relative positions of the first loop part and the second loop part and the first magnetic sensor and the second magnetic sensor are shifted in the predetermined direction, the first magnetic sensor is provided. The second magnetic sensor approaches the upper surface member and leaves the lower surface member, or leaves the upper surface member and approaches the lower surface member.

  When the first magnetic sensor approaches the upper surface member and moves away from the lower surface member, the first magnetic sensor detects the amount of magnetism detected by the magnetic field generated by the current flowing through the upper surface member portion of the first loop. And the amount of magnetism detected by the magnetic field generated by the current flowing through the lower surface member of the first loop is weakened. Therefore, the magnitude of magnetism detected by the first magnetic sensor hardly changes. Similarly, the magnitude of the detected magnetism hardly changes in the second magnetic sensor. Therefore, the influence of the positional deviation in the predetermined direction can be reduced.

  The first loop portion and the second loop portion are connected between a linear first conductive portion and a second conductive portion, and the first conductive portion and the first loop portion or the second loop are connected. In the connection place with the part, the energization direction of the first conduction part and the tangential direction of the connection place of the first loop part or the second loop part are orthogonal to each other.

  According to the present invention, the magnetic flux generated by the current flowing through the first conduction portion reaches the inside of the first loop portion or the second loop portion, and is caused by the first magnetic sensor or the second magnetic sensor. It is possible to prevent a detected magnetic error.

  In addition, the second conducting portion has a linear shape, and the energization direction of the second conducting portion and the first loop at a connection point between the second conducting portion and the first loop portion or the second loop portion. Or a tangential direction of the connection portion of the second loop portion is perpendicular to the portion or the second loop portion.

  According to the present invention, the magnetic flux generated by the current flowing through the second conducting portion reaches the inside of the first loop portion or the second loop portion, and is caused by the first magnetic sensor or the second magnetic sensor. It is possible to prevent a detected magnetic error.

  Moreover, the magnetic flux collection effect by the said 1st loop part and the said 2nd loop can further be heightened by making the said 1st loop part and the said 2nd loop part into the structure of multiple winding.

The block diagram of the current detection apparatus of this invention. Explanatory drawing which showed the shape of a bus bar, and the arrangement | positioning aspect of a 1st magnetic sensor and a 2nd magnetic sensor. Explanatory drawing of the magnetic field produced by the electric current which flows into the 1st loop part and 2nd loop part of a bus-bar. Explanatory drawing about the tolerance improvement with respect to the position shift between a bus-bar, a 1st magnetic sensor, and a 2nd magnetic sensor. Explanatory drawing of the connection aspect of a 1st loop part and a 1st and 2nd conduction | electrical_connection part. Explanatory drawing of other embodiment of the shape of a 1st loop part and a 2nd loop part. Explanatory drawing of the conventional electric current detection apparatus.

  Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram of a current detection device 1 according to the present invention. The current detection device 1 includes a bus bar 10 that connects a motor 2 mounted on a vehicle and its PDU (Power Drive Unit) 3 (the present invention). The first magnetic sensor 20 and the second magnetic sensor 21 are used to detect a current flowing through the first magnetic sensor 20 and the second magnetic sensor 21.

  The current detection device 1 includes a first magnetic sensor 20 and a second magnetic sensor 21, an amplifier 30 that amplifies the magnetic detection signal S 1 of the first magnetic sensor 20, and an amplifier that amplifies the magnetic detection signal S 2 of the second magnetic sensor 21. 31, an amplifier 30 that amplifies the difference between the outputs of the amplifier 30 and the amplifier 31, and a microcomputer 40 to which the output S3 of the amplifier 32 is input.

  A first loop portion 12 and a second loop portion 13 connected to the first conductive portion 11 and the second conductive portion 14 are formed in the middle of the bus bar 10. A first magnetic sensor 20 is disposed inside the first loop portion 12, and a second magnetic sensor 21 is disposed inside the second loop portion 13. In the present embodiment, Hall elements are used for the first magnetic sensor 20 and the second magnetic sensor 21.

  The microcomputer 40 functions as a magnetic calculation unit 41 and a current calculation unit 42 by executing a current detection program held in a memory (not shown). The magnetic calculation means 41 calculates the magnetic field strength H generated by the current flowing through the bus bar 10 based on the magnetic detection signal S3 input to the A / D (analog / digital) conversion input port AD and converted into a digital value. calculate. Further, the current calculation unit 42 calculates the current flowing through the bus bar 10 based on the magnetic field strength H calculated by the magnetic calculation unit 41.

  Next, the shape of the bus bar 10 and the arrangement of the first magnetic sensor 20 and the second magnetic sensor 21 in the present embodiment will be described with reference to FIG.

  The first loop portion 12 and the second loop portion 13 of the bus bar 10 are spaced from each other by connecting the lower surface member 16 connected to the first conduction portion 11 and the upper surface member 15 connected to the second conduction portion 14 by the connection member 17. It is formed by connecting in parallel in the shape of figure 8 with a space. Moreover, the 1st conduction | electrical_connection part 11 is connected with PDU3 (refer FIG. 1), and the 2nd conduction | electrical_connection part 14 is connected with the motor 2 (refer FIG. 1).

Therefore, when the motor 2 is driven, the current I supplied from the PDU 3 to the first conduction member 11 is supplied to the motor 2 through a path of I ₁ → I ₂ → I ₃ → I ₄ → I ₅ . In this case, in the first loop portion 12, a current flows leftward in the circumferential direction (corresponding to the first direction in the circumferential direction of the present invention), and in the second loop portion 13, a current flows rightward in the circumferential direction.

  In addition, the first magnetic sensor 20 is disposed at the inner center portion (the center portion of the inner circumference) of the first loop portion 12, and the second magnetic sensor 21 is disposed at the inner center portion of the second loop portion 13. Has been. Further, the magnetic detection directions of the first magnetic sensor 20 and the second magnetic sensor 21 are in the direction of Sz in the figure (direction perpendicular to the surfaces of the upper surface member 15 and the lower surface member 16).

Next, FIG. 3 is a top view of the first loop portion 12 and the second loop portion 13. In the first loop portion 12, since a current flows in the left direction (I ₁ , I ₄ ), a magnetic field in the H ₁ direction is generated. On the other hand, in the second loop portion 13, since a current flows in the right direction (I ₂ , I ₃ ), a magnetic field in the H ₂ direction is generated.

  Therefore, the direction of the magnetic field at the location of the first magnetic sensor 20 is opposite to the direction of the magnetic field at the location of the second magnetic sensor 21, and the magnetic field generated by the current flowing through the first loop portion 12 of the first magnetic sensor 20. And the detection polarity of the magnetic field generated by the current flowing through the second loop portion 13 of the second magnetic sensor 21 are reversed.

  Since the first loop portion 12 and the second loop portion have substantially the same shape, the magnetic detection signal S1 from the first magnetic sensor 20 and the magnetic detection signal S2 from the second magnetic sensor 21 have opposite polarities. The size is almost the same. Therefore, the amplifier 32 amplifies the magnetic detection signal S1 from the first magnetic sensor 20 and the magnetic detection signal S2 from the second magnetic sensor 21 to amplify the external noise as shown in the following equation (1). Can be canceled.

S3 = A3 {A1 (S1 + Sn) -A1 (-S2 + Sn)}
= A3 {A1 · S1 + A1 · S2 + A1 · Sn-A1 · Sn}
≒ 2A3 ・ A1 ・ S1 (1)
S3: output of the operational amplifier 32, A3: amplification factor of the operational amplifier 32, A1: amplification factors of the amplifiers 30 and 31, S1: output of the magnetic detection signal of the first magnetic sensor 20, S2: second magnetic sensor 21 Magnetic detection signal output (≈S1), Sn: external noise.

  Next, with reference to FIG. 4A and FIG. 4B, the resistance to the positional deviation between the first loop portion 12 and the second loop portion 13 and the first magnetic sensor 20 and the second magnetic sensor 21 is described. explain.

  First, referring to FIG. 4A, the first magnetic sensor 20 is disposed at the center position of the inner circumference circle 17 of the first loop portion 12. Further, the second magnetic sensor 21 is disposed at the center position of the inner circumferential circle 18 of the second loop portion 13.

  In addition, the strength of the magnetic field generated by the current flowing through the first loop portion 12 is made uniform inside the first loop portion 12. Further, inside the second loop portion 13, the strength of the magnetic field generated by the current flowing through the second loop portion 13 is made uniform.

  Therefore, even if the position of the first magnetic sensor 20 is deviated from the center point of the inner circumference circle 17 to, for example, a position 20a, the output level of the magnetic detection signal of the first magnetic sensor 20 hardly changes. Further, even if the position of the second magnetic sensor 21 is shifted from the center point of the inner circumferential circle 18 to, for example, a position 21a, the output level of the magnetic detection signal of the second magnetic sensor 21 hardly changes.

  Therefore, the first magnetic sensor 20 and the second magnetic sensor 21 are rotated by the bus bar 10 in addition to the case where the arrangement positions of the first magnetic sensor 20 and the second magnetic sensor 21 are shifted in the x direction and the y direction in the drawing. Even if it is a case where it shifts | deviates to a direction, if the shift | offset | difference is settled inside the 1st loop part 12 and the 2nd loop part 13, the influence of position shift can be reduced.

  FIG. 4B is a side view of the first loop portion 12 and the second loop portion 13, and the first magnetic sensor 20 and the second magnetic sensor 21 have an intermediate position Zc in the height direction (Z direction). Is arranged. And if the 1st magnetic sensor 20 shifts to the position of 20b of the down direction, the 1st magnetic sensor 20 will approach the lower surface member 16 while separating from the upper surface member 15. FIG.

  In this case, the detection level of the magnetic field generated by the current flowing through the upper surface member 15 is reduced, but the detection level of the magnetic field generated by the current flowing through the lower surface member 16 is increased, so the output level of the magnetic detection signal of the first magnetic sensor 20 is Almost no change.

  Similarly, when the second magnetic sensor 21 is displaced to the position 21b in the upward direction, the second magnetic sensor 21 approaches the upper surface member 15 and moves away from the lower surface member 16. In this case, the detection level of the magnetic field generated by the current flowing through the upper surface member 15 is increased, but the detection level of the magnetic field generated by the current flowing through the lower surface member 16 is decreased, so the output level of the magnetic detection signal of the second magnetic sensor 20 is Almost no change.

  Thus, even if the first magnetic sensor 20 and the second magnetic sensor 21 are displaced in the Z direction within the range between the upper surface member 15 and the lower surface member 16, the first magnetic sensor 20 and the second magnetic sensor 21 are used. The output level of the magnetic detection signal is almost unchanged. Therefore, it is possible to reduce the influence of the positional deviation in the Z direction.

  Next, with reference to FIG. 5A and FIG. 5B, a connection form between the first loop portion 12, the first conduction portion 11, and the second conduction portion 14 will be described.

  As shown in FIG. 5A, the tangential direction C1 of the connecting portion of the first loop portion 12 with the second conducting portion 14 and the energizing direction C2 of the second conducting portion 14 are perpendicular to each other. Further, the tangential direction of the connecting portion of the first loop portion 12 with the first conducting portion 11 and the energizing direction of the first conducting portion 11 are also perpendicular.

  In this case, the magnetic field H 3 generated by the current flowing through the second conduction portion 14 does not reach the inside of the first loop portion 12 and the second loop portion 13. In the first conduction part 11, the magnetic field generated by the current flowing through the first conduction part 11 does not reach the inside of the first loop part 12 and the second loop part 13.

  Therefore, it is possible to prevent the accuracy of magnetic detection by the first magnetic sensor 20 and the second magnetic sensor 21 from being deteriorated due to the influence of the current flowing through the first conductive portion 11 and the second conductive portion 14.

Moreover, as shown in FIG.5 (b), the 1st conduction | electrical_connection part 11 and the 2nd conduction | electrical_connection part 14 are arrange | positioned closely, and the direction of the electric current which flows is reverse. In this case, the magnetic field H ₁₁ caused by the current I ₁₁ flowing through the first conductive portion 11, since the direction of the magnetic field H ₁₂ caused by the current I ₁₂ flowing in the second conductive portion 14 is reversed, the magnetic field H ₁₁ and the magnetic field H ₁₂ Can cancel each other. And this makes it possible to field H ₁₁ and the magnetic field H ₁₂ to reduce the influence on the electronic parts.

  In the present embodiment, the first loop portion 12 and the second loop portion 13 are circular, but may be any shape that forms a loop. For example, as shown in FIGS. 6 (a) and 6 (c), it may have a quadrangular shape, or may have an octagonal shape as shown in FIG. 6 (b).

  In the present embodiment, the first magnetic sensor 20 and the second magnetic sensor 21 are arranged between the upper surface member 15 and the lower surface member 16 in the first loop portion 12 and the second loop portion 13. Even if this configuration is not employed, the effects of the present invention can be obtained.

  Moreover, in this Embodiment, as shown to Fig.5 (a) and FIG.5 (b), the tangential direction of the connection location with the 2nd conduction | electrical_connection part 14 of the 1st loop part 12, and the 2nd conduction | electrical_connection part 14 are shown. Although the energizing directions are orthogonal to each other, the effect of the present invention can be obtained even when such a connection form is not used.

  In addition, the first loop portion and the second loop portion may be configured as a multiple winding configuration to further enhance the magnetic flux collection effect by the first loop and the second loop.

  In the present embodiment, a Hall element is used as the magnetic sensor of the present invention, but other types of magnetic sensors may be used.

  Further, the upper surface member is formed by forming a pattern of the upper surface member on the front surface layer and a pattern of the lower surface member on the back surface layer using the three-layer substrate having the insulating layer between the first loop portion and the second loop portion. This pattern and the pattern of the lower surface member may be connected by a through hole.

  DESCRIPTION OF SYMBOLS 1 ... Current detection apparatus, 10 ... Bus bar, 11 ... 1st conduction | electrical_connection part, 12 ... 1st loop part, 13 ... 2nd loop part, 14 ... 2nd conduction | electrical_connection part, 15 ... Upper surface member, 16 ... Lower surface member, 17 ... Connection member, 20 ... first magnetic sensor, 21 ... second magnetic sensor, 40 ... microcomputer, 41 ... magnetic calculation means, 42 ... current calculation means.

Claims (5)

In the current detection device for obtaining the current by detecting the magnetism generated by the current flowing through the conductor by using the first magnetic sensor and the second magnetic sensor without using the core for converging the magnetic flux,
The conductor has a first loop portion in which the detected current flows in a first direction in the circumferential direction, and a second loop portion in which the detected current flows in a direction opposite to the first direction in the circumferential direction,
The first magnetic sensor is disposed inside the first loop portion so that a magnetic detection direction is aligned with a direction of a magnetic field generated by a current flowing through the first loop portion, and the second magnetic sensor is Inside the second loop part, the magnetic detection direction is arranged in accordance with the direction of the magnetic field generated by the current flowing through the second loop part,
The detection polarity of magnetism generated by the current flowing through the first loop portion of the first magnetic sensor and the detection polarity of magnetism generated by the current flowing through the second loop portion of the second magnetic sensor are the same, and the first When the magnetic sensor and the second magnetic sensor are arranged, the magnetism generated by the current flowing through the conductor is calculated based on the difference between the outputs of the first magnetic sensor and the second magnetic sensor, and the first When the magnetism detection polarity generated by the current flowing through the first loop portion of the magnetic sensor and the magnetism detection polarity generated by the current flowing through the second loop portion of the second magnetic sensor are arranged in reverse, Magnetism calculating means for calculating magnetism generated by a current flowing through the conductor based on a sum of outputs of the first magnetic sensor and the second magnetic sensor;
A current detection device comprising: current calculation means for calculating a current flowing through the conductor based on the magnetism calculated by the magnetism calculation means. The current detection device according to claim 1,
The first loop portion and the second loop portion are formed by an upper surface member and a lower surface member that are arranged in parallel with an interval in a predetermined direction, and the first magnetic sensor and the second magnetic sensor are the upper surface member. And a current detecting device disposed between the lower surface member and the lower surface member. In the current detection device according to claim 1 or 2,
The first loop part and the second loop part are connected between a linear first conductive part and a second conductive part,
At the connection point between the first conduction part and the first loop part or the second loop part, the energization direction of the first conduction part and the tangent line of the connection part of the first loop part or the second loop part A current detection device characterized in that the direction is orthogonal. In the current detection device according to claim 3,
The second conducting portion is linear;
At the connection point between the second conduction part and the first loop part or the second loop part, the energization direction of the second conduction part and the tangent line of the connection part of the first loop part or the second loop part A current detection device characterized in that the direction is orthogonal. In the current detection device according to any one of claims 1 to 4,
The current detection device according to claim 1, wherein the first loop portion and the second loop portion have a multiple winding configuration.

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