JP2013044541A - Shunt resistance type current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shunt resistance type current sensor capable of further improving detection accuracy of current to be measured.SOLUTION: A shunt resistance type current sensor 1 comprises: a bus bar 10 composed of a conductive member; a circuit board 20 disposed on the bus bar 10; a voltage detecting IC 30 that is disposed on the circuit board 20, and that detects a voltage value applied to the circuit board 20 for detecting a magnitude of current to be measured flowing in the bus bar 10; and a correcting circuit pattern 40 that is formed on the circuit board 20, and that cancels out induction current caused by a magnetic field generated by the current to be measured flowing in the bus bar 10. Further, the correcting circuit pattern 40 is composed of a circuit pattern 41 formed on front and rear sides of the circuit board 20, and a throughhole 42 for electrically connecting the circuit pattern 41 formed on the front and rear sides, and forms a coil across the front and rear sides of the circuit board 20 by connecting the circuit pattern 41 to the throughhole 42.

Description

  The present invention relates to a shunt resistance type current sensor.

  Conventionally, in order to measure a pulse current, a large alternating current, and the like, a shunt resistance type current sensor has been proposed in which a current to be measured is passed through a shunt resistor having a known resistance value and a voltage drop generated in the shunt resistor is measured. In such a shunt resistance type current sensor, an inductance component is generated when an attempt is made to measure a high-frequency current or the like, and an error occurs in the measured current.

  Therefore, a shunt resistance type current sensor with a reduced inductance component has been proposed. In this shunt resistance type current sensor, an inductance component is reduced by narrowing the distance between the resistor and the fixed terminal plate, thereby reducing the detection error of the current to be measured (see Patent Document 1).

JP 2002-319501 A

  However, since the shunt resistance type current sensor described in Patent Document 1 has an interval between the resistor and the fixed terminal plate, the inductance component is not small and remains, and a detection error occurs in the current to be measured.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a shunt resistance type current sensor capable of further improving the detection accuracy of the current to be measured. It is in.

  A shunt resistance type current sensor of the present invention includes a bus bar made of a conductive member, a circuit board formed on the bus bar and formed with a voltage detection circuit pattern electrically connected in parallel to the bus bar, A voltage detection means for detecting a voltage value applied to the voltage detection circuit pattern for detecting the magnitude of the current to be measured flowing through the bus bar, and being formed on the circuit board; A correction circuit pattern that cancels out the induced current generated by the magnetic field generated by the current to be measured flowing through the bus bar, and the correction circuit pattern electrically connects the circuit pattern formed on the front and back of the circuit board and the circuit pattern formed on the front and back. And a conductive pattern that is electrically connected, and a circuit pattern is connected to the conductive portion to form a coil that extends across the circuit board. To.

  According to the shunt resistance type current sensor of the present invention, the correction circuit pattern for canceling the induced current generated by the magnetic field generated by the current to be measured flowing through the bus bar is provided, and this correction circuit pattern forms a coil across the front and back of the circuit board. ing. For this reason, even when the detected current becomes a high frequency, a detection error due to the induced current is less likely to occur, and the detection accuracy of the measured current can be further improved.

  ADVANTAGE OF THE INVENTION According to this invention, the shunt resistance type current sensor which can improve the detection accuracy of the to-be-measured current further can be provided.

It is a top view which shows the shunt resistance type current sensor which concerns on embodiment of this invention. It is a side view which shows the shunt resistance type current sensor which concerns on embodiment of this invention. It is a back view which shows the shunt resistance type current sensor which concerns on this embodiment. It is a perspective view which shows the correction circuit pattern of the shunt resistance type current sensor concerning this embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a top view showing a shunt resistance type current sensor according to an embodiment of the present invention, and FIG. 2 is a side view showing the shunt resistance type current sensor according to an embodiment of the present invention. In FIG. 2, the magnetic flux is also shown for convenience of explanation.

  As shown in the figure, the shunt resistance type current sensor 1 includes a bus bar 10, a circuit board 20, a voltage detection IC (voltage detection means) 30, and a connection unit 50.

  The bus bar 10 is a flat plate-shaped conductive member, and is made of, for example, a copper manganese alloy or a copper nickel alloy. The bus bar 10 is formed into a desired shape by press molding from a flat steel material. The bus bar 10 serves as a shunt resistor so that a current to be measured flows. In the present embodiment, the bus bar 10 has a flat plate shape, but is not limited thereto, and may be a curved shape as in Patent Document 1.

  The circuit board 20 is installed on the bus bar 10 and has a voltage detection circuit pattern 21 formed thereon. The voltage detection circuit pattern 21 is electrically connected in parallel to the bus bar 10 via the two connection portions 50, and a part of the current to be measured flows.

  The voltage detection IC 30 is installed on the voltage detection circuit pattern 21 of the circuit board 20 and detects a voltage value applied to the voltage detection circuit pattern 21 in order to detect the magnitude of the current to be measured flowing through the bus bar 10. Is. The voltage drop generated in the bus bar 10 is measured by the detection of the voltage value by the voltage detection IC 30.

  Here, in the shunt resistance type current sensor 1, when a current to be measured flows, a magnetic flux is generated and an induced current flows as shown in FIG. That is, as apparent from FIG. 2, a closed circuit (coil) is formed by the bus bar 10, the voltage detection circuit pattern 21 of the circuit board 20, and the connection portion 50, and an induced current flows through this closed circuit. This deteriorates the detection accuracy of the current to be measured.

  Therefore, the shunt resistance type current sensor 1 according to the present embodiment includes a correction circuit pattern 40. FIG. 3 is a back view showing the shunt resistance type current sensor 1 according to this embodiment, and FIG. 4 is a perspective view showing a correction circuit pattern 40 of the shunt resistance type current sensor 1 according to this embodiment. In FIG. 4, only the circuit board 20 and the correction circuit pattern 40 are illustrated for convenience.

  As shown in FIGS. 1, 3 and 4, the correction circuit pattern 40 is formed on the circuit board 20. The correction circuit pattern 40 includes a circuit pattern 41 formed on the front and back surfaces of the circuit board 20 and a through hole (conductive portion) 42 that electrically connects the circuit patterns 41 formed on the front and back surfaces.

  Specifically, in the present embodiment, the circuit pattern 41 includes first to fifth circuit patterns 41a to 41e, and the through hole 42 includes first to fourth through holes 42a to 42d.

  The first circuit pattern 41 a is formed by branching from the voltage detection circuit pattern 21 at a point A between the connection portion 50 on the input side of the current to be measured and the voltage detection IC 30. It extends along the flow direction and reaches the first through hole 42a.

  The first through hole 42a extends to the back surface of the circuit board 20, and is connected to the second circuit pattern 41b on the back surface side. The second circuit pattern 41b extends in the reverse direction of the current to be measured on the back surface side of the circuit board 20, and reaches the second through hole 42b. The second through hole 42b extends to the surface of the circuit board 20, and is connected to the third circuit pattern 41c on the surface side.

  The third circuit pattern 41c extends along the flow direction of the current to be measured on the surface side of the circuit board 20, and reaches the third through hole 42c. Similar to the first through hole 42a, the third through hole 42c extends to the back surface of the circuit board 20, and is connected to the fourth circuit pattern 41d on the back surface side.

  Similar to the second circuit pattern 41b, the fourth circuit pattern 41d extends in the reverse direction of the flow of the current to be measured on the back side of the circuit board 20, and reaches the fourth through hole 42d. Similarly to the second through hole 42b, the fourth through hole 42d extends to the surface of the circuit board 20, and is connected to the fifth circuit pattern 41e on the surface side.

  The fifth circuit pattern 41e extends along the flow direction of the current to be measured on the surface side of the circuit board 20, and at a point B between the connection portion 50 on the output side of the current to be measured and the voltage detection IC 30. The voltage detection circuit pattern 21 is connected.

  As described above, the correction circuit pattern 40 forms a coil across the front and back of the circuit board 20 by connecting the circuit pattern 41 to the through hole 42. The correction circuit pattern 40 is a coil extending in a direction perpendicular to the direction in which the current to be measured flows. Therefore, the magnetic flux generated when the current to be measured flows is canceled out. Specifically, an induced current flows through the correction circuit pattern 40 as shown by the arrows in FIGS. 1, 3, and 4, and a magnetic flux that cancels the magnetic flux shown in FIG. 2 is generated. Therefore, the shunt resistance type current sensor 1 according to the present embodiment is less likely to generate a detection error due to the induced current even when the current to be detected becomes a high frequency, and can further improve the detection accuracy of the current to be measured. .

  The shape of the correction circuit pattern 40 is set so that the amount of magnetic flux cancels out the magnetic flux generated when the current to be measured flows. Further, the circuit board 20 may be provided with a power supply circuit, an arithmetic processing unit, and the like in addition to those illustrated.

  Next, the operation of the shunt resistance type current sensor 1 according to the present embodiment will be described. First, it is assumed that a current to be measured flows. Thereby, magnetic flux is generated and an induced current as shown in FIG. 2 is generated.

  On the other hand, a part of the current to be measured flows to the circuit board 20 through the connection portion 50, reaches the voltage detection IC 30 through the input-side voltage detection circuit pattern 21, and passes through the output-side voltage detection circuit pattern 21 and the connection portion 50. 10 is reached. The voltage detection IC 30 detects a voltage value applied to the voltage detection circuit pattern 21.

  Here, when the current to be measured flows, a current also flows in the correction circuit pattern 40, and an induced current is generated so as to cancel the induced current shown in FIG. Therefore, if the shape or the like of the correction circuit pattern 40 is set to be a predetermined one, the correction circuit pattern 40 can generate an induction current sufficient to cancel the induction current shown in FIG. Therefore, the voltage measurement accuracy by the voltage detection IC 30 can be increased, and the detection accuracy of the current to be measured can be further improved.

  Thus, according to the shunt resistance type current sensor 1 according to the present embodiment, the correction circuit pattern 40 that cancels the induced current generated by the magnetic field generated by the current to be measured flowing through the bus bar 10 is provided. A coil is formed across the front and back of the circuit board 20. For this reason, even when the detected current becomes a high frequency, a detection error due to the induced current is less likely to occur, and the detection accuracy of the measured current can be further improved.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention.

  For example, in the shunt resistance type current sensor 1 according to the present embodiment, the number of coil turns of the correction circuit pattern 40 can be changed as appropriate. Further, the position is not limited to that shown in the figure. In addition, a circuit board on which only the correction circuit pattern 40 is formed may be provided, and this board and the circuit board 20 on which the voltage detection IC 30 is mounted may be electrically connected.

DESCRIPTION OF SYMBOLS 1 ... Shunt resistance type current sensor 10 ... Bus bar 20 ... Circuit board 21 ... Voltage detection circuit pattern 30 ... Voltage detection IC (voltage detection means)
40 ... Correction circuit pattern 41 ... Circuit pattern 42 ... Through hole (connection part)
50 ... connection part

Claims (1)

A bus bar made of a conductive member;
A circuit board provided on the bus bar and formed with a voltage detection circuit pattern electrically connected in parallel to the bus bar;
A voltage detection unit that is installed on the voltage detection circuit pattern of the circuit board and detects a voltage value applied to the voltage detection circuit pattern in order to detect the magnitude of the current to be measured flowing through the bus bar;
A correction circuit pattern that is formed on the circuit board and cancels an induced current generated by a magnetic field generated by a current to be measured flowing in the bus bar, and
The correction circuit pattern includes a circuit pattern formed on the front and back of the circuit board and a conductive portion that electrically connects the circuit pattern formed on the front and back, and the circuit pattern is connected to the conductive portion. A shunt resistance type current sensor characterized in that a coil is formed across the front and back of the circuit board.

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