JP2019152607A - Current measuring device - Google Patents

Current measuring device Download PDF

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JP2019152607A
JP2019152607A JP2018039692A JP2018039692A JP2019152607A JP 2019152607 A JP2019152607 A JP 2019152607A JP 2018039692 A JP2018039692 A JP 2018039692A JP 2018039692 A JP2018039692 A JP 2018039692A JP 2019152607 A JP2019152607 A JP 2019152607A
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current
measured
magnetic sensors
magnetic field
conductor
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JP7114943B2 (en
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一馬 竹中
Kazuma Takenaka
一馬 竹中
徹也 石川
Tetsuya Ishikawa
徹也 石川
美菜子 寺尾
Minako Terao
美菜子 寺尾
晃太朗 小河
Kotaro Ogawa
晃太朗 小河
紗希 小箱
Saki KOBAKO
紗希 小箱
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Yokogawa Electric Corp
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Yokogawa Electric Corp
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Priority to EP19760523.1A priority patent/EP3761044A4/en
Priority to KR1020207024038A priority patent/KR102412180B1/en
Priority to US16/971,927 priority patent/US11360124B2/en
Priority to CN201980015287.6A priority patent/CN111771128B/en
Priority to PCT/JP2019/004009 priority patent/WO2019167565A1/en
Priority to EP22195147.8A priority patent/EP4130757B1/en
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Abstract

To provide a current measuring device that ca be flexibly arranged, and with which it is possible to contactlessly measure a DC current and a low-frequency AC current flowing in one of reciprocating current paths with high accuracy.SOLUTION: A current measuring device 1 comprises: three tri-axis magnetic sensors 11, 12, 13 designed to measure a current I flowing in one of a pair of measurement conductors MC1, MC2 (e.g., a measurement conductor MC1) in which the current I flows in mutually opposite directions, and arranged with a predefined physical relationship in such a way that the respective magneto-sensitive directions are parallel to each other; and an arithmetic unit for calculating a current I flowing in one of the measurement conductors MC1, MC2 (e.g., the measurement conductor MC1) on the basis of the detection results of the three tri-axis magnetic sensors 11, 12, 13 and the physical relationship of the three tri-axis magnetic sensors 11, 12, 13, after excluding the effect of a magnetic field generated by a current I flowing in the other of the measurement conductors MC1, MC2 (e.g., the measurement conductor MC2).SELECTED DRAWING: Figure 1

Description

本発明は、電流測定装置に関する。   The present invention relates to a current measuring device.

従来から、被測定導体に流れる電流を非接触で直接的に測定することが可能な様々な電流測定装置が開発されている。このような電流測定装置の代表的なものとしては、例えばＣＴ（Current Transformer：変流器）方式の電流測定装置、ゼロフラックス方式の電流測定装置、ロゴスキー方式の電流測定装置、ホール素子方式の電流測定装置等が挙げられる。   Conventionally, various current measuring apparatuses capable of directly measuring a current flowing through a conductor to be measured without contact have been developed. Typical examples of such current measuring devices include a CT (Current Transformer) current measuring device, a zero flux current measuring device, a Rogowski current measuring device, and a Hall element method. Examples include current measuring devices.

例えば、ＣＴ方式及びゼロフラックス方式の電流測定装置は、巻線が巻回された磁気コアを被測定導体の周囲に設け、被測定導体（一次側）に流れる電流によって磁気コアに生ずる磁束を打ち消すように巻線（二次側）に流れる電流を検出することで、被測定導体に流れる電流を測定するものである。また、ロゴスキー方式の電流測定装置は、ロゴスキーコイル（空芯コイル）を被測定導体の周囲に設け、被測定導体に流れる交流電流によって生ずる磁界がロゴスキーコイルと鎖交することでロゴスキーコイルに誘起される電圧を検出することで、被測定導体に流れる電流を測定するものである。   For example, CT and zero flux current measuring devices provide a magnetic core around which a winding is wound around a conductor to be measured, and cancel the magnetic flux generated in the magnetic core by the current flowing through the conductor to be measured (primary side). Thus, the current flowing through the conductor to be measured is measured by detecting the current flowing through the winding (secondary side). In addition, the Rogowski current measuring device has a Rogowski coil (air core coil) around the conductor to be measured, and the magnetic field generated by the alternating current flowing through the conductor to be measured is linked to the Rogowski coil. By detecting the voltage induced in the coil, the current flowing through the conductor to be measured is measured.

以下の特許文献１には、ゼロフラックス方式の電流測定装置の一例が開示されている。また、以下の特許文献２には、複数の磁気センサを用いた電流測定装置が開示されている。具体的に、以下の特許文献２に開示された電流測定装置は、被測定導体に対してそれぞれ異なる距離をとって２つの磁気センサを配置し、これら磁気センサの出力から磁気センサと被測定導体との距離を求め、求めた距離を用いて被測定導体に流れる電流の大きさを求めている。   The following Patent Document 1 discloses an example of a zero flux type current measuring device. Patent Document 2 below discloses a current measuring device using a plurality of magnetic sensors. Specifically, in the current measuring device disclosed in Patent Document 2 below, two magnetic sensors are arranged at different distances from the conductor to be measured, and the magnetic sensor and the conductor to be measured are output from the outputs of these magnetic sensors. And the magnitude of the current flowing through the measured conductor is obtained using the obtained distance.

特開２００５−５５３００号公報JP 2005-55300 A 特開２０１１−１６４０１９号公報JP 2011-164019 A

ところで、近年、ハイブリッド自動車（ＨＶ：Hybrid Vehicle）や電気自動車（ＥＶ：Electric Vehicle）の開発工程において、ＳｉＣ（シリコンカーバイド）等のパワー半導体のピンに流れる電流や、組み立て後のバスバーに流れる電流を直接的に測定したいという要求がある。パワー半導体はピンのピッチが狭いものが多く、バスバーは周辺のスペースが限られている場所に設置されることがあり、このようなパワー半導体やバスバー等に対して、電流測定時の設置を柔軟に行うことが可能な電流測定装置が望まれている。また、ハイブリッド自動車や電気自動車では、例えばバッテリから供給される直流電流やモータに流れる交流電流が取り扱われるため、直流電流及び低周波（例えば、十［Ｈｚ］程度）の交流電流を非接触で測定可能な電流測定装置が望まれている。   By the way, in recent years, in the development process of hybrid vehicles (HV) and electric vehicles (EV), the current that flows in the pins of power semiconductors such as SiC (silicon carbide) and the current that flows in the bus bar after assembly. There is a demand for direct measurement. Many power semiconductors have narrow pin pitches, and bus bars may be installed in places where the space around them is limited. For such power semiconductors and bus bars, etc., flexible installation during current measurement is possible. There is a demand for a current measuring device that can be used in the future. Moreover, in a hybrid vehicle or an electric vehicle, for example, a direct current supplied from a battery or an alternating current flowing in a motor is handled, so a direct current and a low frequency (for example, about 10 Hz) alternating current are measured in a non-contact manner. A possible current measuring device is desired.

しかしながら、上述した特許文献１に開示されたゼロフラックス方式の電流測定装置は、ある程度の大きさを有する磁気コアを被測定導体の周囲に設ける必要があることから、狭い場所への設置が困難であるという問題がある。また、上述したロゴスキー方式の電流測定装置は、ロゴスキーコイルに誘起される電圧を検出していることから、原理的に直流電流の測定を行うことはできないという問題がある。また低周波領域では、出力信号が微弱であるとともに位相がずれるため、測定精度が悪いという問題がある。また、上述した特許文献２に開示された電流測定装置は、磁気センサの感磁方向を被測定導体の円周方向に一致させる必要があることから、磁気センサの配置が制限されてしまい柔軟な配置が困難であるという問題がある。   However, the zero flux type current measuring device disclosed in Patent Document 1 described above requires a magnetic core having a certain size to be provided around the conductor to be measured, so that it is difficult to install in a narrow place. There is a problem that there is. In addition, the above-described Rogowski-type current measuring device has a problem in that it cannot measure a DC current in principle because it detects a voltage induced in the Rogowski coil. Also, in the low frequency region, there is a problem that the measurement accuracy is poor because the output signal is weak and the phase is shifted. Moreover, since the current measuring device disclosed in Patent Document 2 described above needs to make the magnetic sensing direction of the magnetic sensor coincide with the circumferential direction of the conductor to be measured, the arrangement of the magnetic sensor is limited and is flexible. There is a problem that placement is difficult.

また、電流は、一般的に電源の正極から流出した後に、負荷等を経て電源の負極に流入するため、電源から供給される電流の電流経路には、電流が電源の正極から流出する経路（往路）と、電流が電源の負極に流入する経路（復路）とがある。尚、前者の経路を復路といい、後者の経路を往路という場合もある。このため、電流経路の何れか一方（例えば、往路）を流れる電流を測定する場合には、電流経路の何れか他方（例えば、復路）を流れる電流によって生成される磁界の影響を受け、測定精度が悪化してしまうという問題がある。   In addition, since the current generally flows out from the positive electrode of the power supply and then flows into the negative electrode of the power supply through a load or the like, the current path of the current supplied from the power supply includes a path ( A forward path) and a path through which current flows into the negative electrode of the power supply (return path). The former route may be referred to as a return route, and the latter route may be referred to as an outbound route. Therefore, when measuring the current flowing through one of the current paths (for example, the forward path), the measurement accuracy is affected by the magnetic field generated by the current flowing through the other of the current paths (for example, the return path). There is a problem that gets worse.

本発明は上記事情に鑑みてなされたものであり、柔軟な配置が可能であり、往復する電流経路の何れか一方を流れる直流電流及び低周波の交流電流を非接触で精度良く測定することができる電流測定装置を提供することを目的とする。   The present invention has been made in view of the above circumstances, can be arranged flexibly, and can accurately measure a direct current and a low-frequency alternating current flowing through one of the reciprocating current paths in a non-contact manner. An object of the present invention is to provide a current measuring device capable of performing the above.

上記課題を解決するために、本発明の一態様による電流測定装置は、互いに反対方向に電流が流れる一対の被測定導体（ＭＣ１、ＭＣ２）の何れか一方に流れる電流（Ｉ）を測定する電流測定装置（１）であって、各々の感磁方向が互いに平行になるように、予め規定された位置関係をもって配置された３つの三軸磁気センサ（１１、１２、１３）と、前記３つの三軸磁気センサの検出結果と前記３つの三軸磁気センサの位置関係とに基づいて、前記被測定導体の何れか他方に流れる電流によって生成される磁界の影響を排除した上で、前記被測定導体の何れか一方に流れる電流を求める演算部（２５）と、を備える。
また、本発明の一態様による電流測定装置は、前記演算部が、前記３つの三軸磁気センサの検出結果と前記３つの三軸磁気センサの位置関係とを用いて、前記被測定導体の何れか他方に流れる電流によって生成される磁界を推定する磁界推定部（２５ｂ）と、前記３つの三軸磁気センサの検出結果と前記３つの三軸磁気センサの位置関係とを用いて、前記被測定導体の何れか一方に対する前記３つの三軸磁気センサの少なくとも１つの距離を推定する距離推定部（２５ｃ）と、前記距離推定部によって推定された距離と、前記距離推定部によって距離が推定された三軸磁気センサの検出結果から前記磁界推定部によって推定された磁界を差し引いたものとに基づいて、前記被測定導体の何れか一方に流れる電流を求める電流算出部（２５ｄ）と、を備える。
また、本発明の一態様による電流測定装置において、前記磁界推定部によって推定される磁界は、前記被測定導体の何れか他方に流れる電流によって生成される磁界が、前記３つの三軸磁気センサに近似的に均一に作用するとみなした場合の磁界である。
また、本発明の一態様による電流測定装置は、前記演算部が、前記３つの三軸磁気センサの検出結果に含まれる雑音成分を除去する雑音除去部（２５ａ）を更に備えており、前記雑音除去部によって雑音成分が除去された前記３つの三軸磁気センサの検出結果を用いて前記被測定導体の何れか一方に流れる電流を求める。
また、本発明の一態様による電流測定装置は、前記雑音除去部が、予め規定された一定の期間毎に得られる、前記３つの三軸磁気センサの検出結果の各々に対し、平均化処理又は二乗和平方根処理を個別に行うことで、前記３つの三軸磁気センサの検出結果に含まれる雑音成分をそれぞれ除去する。
また、本発明の一態様による電流測定装置は、前記３つの三軸磁気センサを備えるセンサヘッド（１０）と、前記演算部を備える回路部（２０）と、を備える。
また、本発明の一態様による電流測定装置は、前記３つの三軸磁気センサの検出結果を示す信号が、ディジタル信号である。 In order to solve the above problems, a current measuring device according to one aspect of the present invention measures a current (I) flowing in one of a pair of conductors to be measured (MC1, MC2) in which currents flow in opposite directions. The measuring device (1), which includes three three-axis magnetic sensors (11, 12, 13) arranged in a predetermined positional relationship so that the respective magnetic sensing directions are parallel to each other, and the three Based on the detection result of the three-axis magnetic sensor and the positional relationship of the three three-axis magnetic sensors, the influence of the magnetic field generated by the current flowing through one of the measured conductors is eliminated, and then the measured And an arithmetic unit (25) for obtaining a current flowing through one of the conductors.
Further, in the current measurement device according to one aspect of the present invention, the calculation unit uses any of the detection results of the three triaxial magnetic sensors and the positional relationship of the three triaxial magnetic sensors to determine which of the conductors to be measured. The magnetic field estimator (25b) for estimating the magnetic field generated by the current flowing through the other, the detection results of the three triaxial magnetic sensors, and the positional relationship of the three triaxial magnetic sensors. A distance estimation unit (25c) that estimates at least one distance of the three triaxial magnetic sensors with respect to any one of the conductors, a distance estimated by the distance estimation unit, and a distance estimated by the distance estimation unit A current calculation unit (25d) for obtaining a current flowing in one of the measured conductors based on a result obtained by subtracting the magnetic field estimated by the magnetic field estimation unit from the detection result of the triaxial magnetic sensor , Comprising a.
In the current measurement device according to the aspect of the present invention, the magnetic field estimated by the magnetic field estimation unit may be a magnetic field generated by a current flowing through one of the measured conductors in the three triaxial magnetic sensors. It is a magnetic field when it is assumed that it acts approximately uniformly.
In the current measurement device according to one aspect of the present invention, the calculation unit further includes a noise removal unit (25a) that removes a noise component included in the detection results of the three triaxial magnetic sensors. Using the detection results of the three three-axis magnetic sensors from which the noise component has been removed by the removing unit, a current flowing through one of the measured conductors is obtained.
Further, in the current measuring device according to one aspect of the present invention, the noise removing unit performs an averaging process on each of the detection results of the three three-axis magnetic sensors obtained every predetermined period. By performing the square sum square root processing individually, noise components included in the detection results of the three three-axis magnetic sensors are removed.
Moreover, the current measuring device according to one aspect of the present invention includes a sensor head (10) including the three triaxial magnetic sensors, and a circuit unit (20) including the arithmetic unit.
In the current measurement device according to one aspect of the present invention, the signals indicating the detection results of the three triaxial magnetic sensors are digital signals.

本発明によれば、柔軟な配置が可能であり、往復する電流経路の何れか一方を流れる直流電流及び低周波の交流電流を非接触で精度良く測定することができるという効果が得られる。   According to the present invention, flexible arrangement is possible, and it is possible to obtain an effect that a direct current and a low-frequency alternating current flowing through one of the reciprocating current paths can be accurately measured without contact.

本発明の一実施形態による電流測定装置を模式的に示す図である。It is a figure showing typically the current measuring device by one embodiment of the present invention. 本発明の一実施形態による電流測定装置の要部構成を示すブロック図である。It is a block diagram which shows the principal part structure of the electric current measurement apparatus by one Embodiment of this invention. 本発明の一実施形態による電流測定装置による電流の測定原理を説明するための図である。It is a figure for demonstrating the measurement principle of the electric current by the electric current measuring apparatus by one Embodiment of this invention. 被測定導体及び三軸磁気センサを、図３中の方向Ｄ１から見た図である。It is the figure which looked at the to-be-measured conductor and the triaxial magnetic sensor from the direction D1 in FIG. 本発明の一実施形態による電流測定装置の動作の概要を示すフローチャートである。It is a flowchart which shows the outline | summary of operation | movement of the current measurement apparatus by one Embodiment of this invention. 図５中のステップＳ１４の処理の詳細を示すフローチャートである。It is a flowchart which shows the detail of a process of step S14 in FIG.

以下、図面を参照して本発明の一実施形態による電流測定装置について詳細に説明する。   Hereinafter, a current measuring apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

〈電流測定装置の構成〉
図１は、本発明の一実施形態による電流測定装置を模式的に示す図である。図１に示す通り、本実施形態の電流測定装置１は、ケーブルＣＢによって接続されたセンサヘッド１０及び回路部２０を備えており、被測定導体ＭＣ１，ＭＣ２の何れか一方に流れる電流Ｉを非接触で直接的に測定する。尚、本実施形態では、被測定導体ＭＣ１に流れる電流Ｉを測定する場合を例に挙げて説明する。 <Configuration of current measuring device>
FIG. 1 is a diagram schematically showing a current measuring device according to an embodiment of the present invention. As shown in FIG. 1, the current measuring device 1 of the present embodiment includes a sensor head 10 and a circuit unit 20 connected by a cable CB, and a current I flowing through one of the conductors MC1 and MC2 to be measured. Measure directly on contact. In the present embodiment, a case where the current I flowing through the conductor to be measured MC1 is measured will be described as an example.

尚、被測定導体ＭＣ１，ＭＣ２は、例えばパワー半導体のピンやバスバー等の任意の導体である。以下では、説明を簡単にするために、被測定導体ＭＣ１，ＭＣ２は、円柱形状の導電であるとする。被測定導体ＭＣ１，ＭＣ２に流れる電流Ｉは、その流れの方向が互いに逆である。以下、被測定導体ＭＣ１を流れる電流の電流経路を「往路」といい、被測定導体ＭＣ２を流れる電流の電流経路を「復路」ということがある。   The measured conductors MC1 and MC2 are arbitrary conductors such as power semiconductor pins and bus bars, for example. Hereinafter, in order to simplify the description, it is assumed that the conductors to be measured MC1 and MC2 are cylindrical conductive. The currents I flowing in the conductors MC1 and MC2 to be measured have opposite flow directions. Hereinafter, the current path of the current flowing through the measured conductor MC1 may be referred to as “outward path”, and the current path of the current flowing through the measured conductor MC2 may be referred to as “return path”.

センサヘッド１０は、被測定導体ＭＣ１に流れる電流Ｉを非接触で測定するために、被測定導体ＭＣ１に対して任意の位置に任意の姿勢で配置される部材である。このセンサヘッド１０は、被測定導体ＭＣ１，ＭＣ２に流れる電流Ｉによって生成される磁界（例えば、図１中に示す磁界Ｈ１，Ｈ２，Ｈ３）を遮らない材質（例えば、樹脂等）によって形成されている。このセンサヘッド１０は、いわば被測定導体ＭＣ１に流れる電流Ｉを非接触で測定するためのプローブとして用いられるものである。   The sensor head 10 is a member arranged in an arbitrary position at an arbitrary position with respect to the measured conductor MC1 in order to measure the current I flowing through the measured conductor MC1 in a non-contact manner. The sensor head 10 is formed of a material (for example, resin or the like) that does not block a magnetic field (for example, the magnetic fields H1, H2, and H3 shown in FIG. 1) generated by the current I flowing through the conductors to be measured MC1 and MC2. Yes. This sensor head 10 is used as a probe for measuring the current I flowing through the conductor to be measured MC1 in a non-contact manner.

センサヘッド１０には、３つの三軸磁気センサ１１，１２，１３が設けられている。三軸磁気センサ１１，１２，１３は、互いに直交する三軸に感磁方向を有する磁気センサである。三軸磁気センサ１１，１２，１３は、各々の感磁方向が互いに平行になるように、予め規定された位置関係をもって配置されている。例えば、三軸磁気センサ１１，１２，１３の第１軸が互いに平行になり、三軸磁気センサ１１，１２，１３の第２軸が互いに平行になり、且つ三軸磁気センサ１１，１２，１３の第３軸が互いに平行になるように、所定の方向に所定の距離だけ離間するように配置されている。尚、以下では、三軸磁気センサ１１，１２が、第１軸方向に所定の距離だけ離間するように配列され、三軸磁気センサ１１，１３が、第３軸方向に所定の距離だけ離間するように配列されているとする。   The sensor head 10 is provided with three three-axis magnetic sensors 11, 12, and 13. The triaxial magnetic sensors 11, 12, and 13 are magnetic sensors having a magnetosensitive direction on three axes orthogonal to each other. The triaxial magnetic sensors 11, 12, and 13 are arranged with a predetermined positional relationship so that their magnetic sensing directions are parallel to each other. For example, the first axes of the three-axis magnetic sensors 11, 12, 13 are parallel to each other, the second axes of the three-axis magnetic sensors 11, 12, 13 are parallel to each other, and the three-axis magnetic sensors 11, 12, 13 are Are arranged so as to be separated from each other by a predetermined distance in a predetermined direction so that the third axes thereof are parallel to each other. In the following, the triaxial magnetic sensors 11 and 12 are arranged so as to be separated from each other by a predetermined distance in the first axis direction, and the triaxial magnetic sensors 11 and 13 are separated from each other by a predetermined distance in the third axis direction. Is arranged as follows.

三軸磁気センサ１１，１２，１３の検出結果を示す信号は、アナログ信号及びディジタル信号の何れでも良いが、三軸磁気センサ１１，１２，１３の検出結果を示す信号がディジタル信号である場合には、センサヘッド１０と回路部２０とを接続するケーブルＣＢの本数を少なくすることができる。例えば、三軸磁気センサ１１，１２，１３の検出結果を示す信号がアナログ信号である場合には、三軸磁気センサ１１，１２，１３の各々について三軸の検出結果を出力する３本のケーブルＣＢがそれぞれ必要になるため、計９本のケーブルＣＢが必要になるが、三軸磁気センサ１１，１２，１３の検出結果を示す信号がディジタル信号である場合には、１本のケーブルＣＢのみで良い。ケーブルＣＢの本数が少ないと、ケーブルＣＢの屈曲性が向上するため、例えばセンサヘッド１０を狭い空間内に配置する際にハンドリングが容易になる。   The signal indicating the detection result of the triaxial magnetic sensors 11, 12, 13 may be either an analog signal or a digital signal, but when the signal indicating the detection result of the triaxial magnetic sensor 11, 12, 13 is a digital signal. Can reduce the number of cables CB connecting the sensor head 10 and the circuit unit 20. For example, when the signals indicating the detection results of the triaxial magnetic sensors 11, 12, and 13 are analog signals, three cables that output the triaxial detection results for each of the triaxial magnetic sensors 11, 12, and 13 Since each CB is required, a total of nine cables CB are required. However, when the signals indicating the detection results of the three-axis magnetic sensors 11, 12, and 13 are digital signals, only one cable CB is required. Good. When the number of the cables CB is small, the flexibility of the cables CB is improved. For example, when the sensor head 10 is arranged in a narrow space, handling becomes easy.

回路部２０は、センサヘッド１０から出力される検出結果（三軸磁気センサ１１，１２，１３の検出結果）に基づいて、被測定導体ＭＣ１に流れる電流Ｉを測定する。ここで、回路部２０は、被測定導体ＭＣ２に流れる電流Ｉによって生成される磁界の影響を排除した上で、被測定導体ＭＣ１に流れる電流Ｉを測定する。回路部２０は、電流Ｉの測定結果を表示し、或いは外部に出力する。センサヘッド１０と回路部２０とを接続するケーブルＣＢとしては任意のものを用いることができるが、可撓性を有し、取り回しが用意であり、且つ断線が生じ難いものが望ましい。   The circuit unit 20 measures the current I flowing through the conductor to be measured MC1 based on the detection result output from the sensor head 10 (detection results of the triaxial magnetic sensors 11, 12, 13). Here, the circuit unit 20 measures the current I flowing through the measured conductor MC1 after eliminating the influence of the magnetic field generated by the current I flowing through the measured conductor MC2. The circuit unit 20 displays the measurement result of the current I or outputs it to the outside. Although any cable CB for connecting the sensor head 10 and the circuit unit 20 can be used, it is desirable that the cable CB be flexible, ready to be handled, and hardly break.

図２は、本発明の一実施形態による電流測定装置の要部構成を示すブロック図である。尚、図２では、図１に示した構成に対応するブロックについては、同一の符号を付してある。以下では、主に、図２を参照して回路部２０の内部構成の詳細について説明する。図２に示す通り、回路部２０は、操作部２１、表示部２２、メモリ２３、及び演算部２５を備える。   FIG. 2 is a block diagram showing a main configuration of the current measuring device according to one embodiment of the present invention. In FIG. 2, the same reference numerals are assigned to blocks corresponding to the configuration shown in FIG. Below, the detail of the internal structure of the circuit part 20 is mainly demonstrated with reference to FIG. As illustrated in FIG. 2, the circuit unit 20 includes an operation unit 21, a display unit 22, a memory 23, and a calculation unit 25.

操作部２１は、例えば電源ボタン、設定ボタン等の各種ボタンを備えており、各種ボタンに対する操作指示を示す信号を演算部２５に出力する。表示部２２は、例えば例えば７セグメントＬＥＤ（Light Emitting Diode：発光ダイオード）表示器、液晶表示装置等の表示装置を備えており、演算部２５から出力される各種情報（例えば、被測定導体ＭＣ１に流れる電流Ｉの測定結果を示す情報）を表示する。尚、操作部２１及び表示部２２は、物理的に分離されたものであっても良く、表示機能と操作機能とを兼ね備えるタッチパネル式の液晶表示装置のように物理的に一体化されたものであっても良い。   The operation unit 21 includes various buttons such as a power button and a setting button, for example, and outputs signals indicating operation instructions for the various buttons to the calculation unit 25. The display unit 22 includes, for example, a display device such as a 7-segment LED (Light Emitting Diode) display, a liquid crystal display device, and the like, and various information output from the calculation unit 25 (for example, the measured conductor MC1). Information indicating the measurement result of the flowing current I) is displayed. The operation unit 21 and the display unit 22 may be physically separated, or physically integrated like a touch panel type liquid crystal display device having both a display function and an operation function. There may be.

メモリ２３は、例えば揮発性又は不揮発性の半導体メモリを備えており、センサヘッド１０から出力される三軸磁気センサ１１，１２，１３の検出結果、演算部２５の演算結果（被測定導体ＭＣ１に流れる電流Ｉの測定結果）等を記憶する。尚、メモリ２３は、上記の半導体メモリとともに（或いは、上記の半導体メモリに代えて）、例えばＨＤＤ（ハードディスクドライブ）やＳＳＤ（ソリッドステートドライブ）等の補助記憶装置を備えていても良い。   The memory 23 includes, for example, a volatile or non-volatile semiconductor memory, and the detection results of the triaxial magnetic sensors 11, 12, 13 output from the sensor head 10 and the calculation results of the calculation unit 25 (on the conductor MC1 to be measured). The measurement result of the flowing current I) is stored. The memory 23 may include an auxiliary storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive) together with the semiconductor memory (or instead of the semiconductor memory).

演算部２５は、センサヘッド１０から出力される三軸磁気センサ１１，１２，１３の検出結果をメモリ２３に記憶させる。また、演算部２５は、メモリ２３に記憶された三軸磁気センサ１１，１２，１３の検出結果を読み出して、被測定導体ＭＣ１に流れる電流Ｉを求める演算を行う。この演算部２５は、雑音除去部２５ａ、磁界推定部２５ｂ、距離推定部２５ｃ、及び電流算出部２５ｄを備える。   The calculation unit 25 stores the detection results of the triaxial magnetic sensors 11, 12, and 13 output from the sensor head 10 in the memory 23. The calculation unit 25 reads the detection results of the triaxial magnetic sensors 11, 12, and 13 stored in the memory 23, and performs a calculation for obtaining the current I flowing through the conductor to be measured MC1. The calculation unit 25 includes a noise removal unit 25a, a magnetic field estimation unit 25b, a distance estimation unit 25c, and a current calculation unit 25d.

雑音除去部２５ａは、三軸磁気センサ１１，１２，１３の検出結果に含まれる雑音成分を除去する。具体的に、雑音除去部２５ａは、予め規定された一定の期間（例えば、１秒）毎に、三軸磁気センサ１１，１２，１３の各々から得られる複数の検出結果に対し、平均化処理又は二乗和平方根処理を個別に行うことで、三軸磁気センサ１１，１２，１３の検出結果に含まれる雑音成分を除去する。尚、三軸磁気センサ１１，１２，１３からは三軸の検出結果がそれぞれ出力されるが、雑音除去部２５ａによる雑音成分の除去は、各軸の検出結果に対して個別に行われる。このような雑音除去を行うのは、三軸磁気センサ１１，１２，１３のＳＮ比（信号対雑音比）を向上させて、電流Ｉの測定精度を高めるためである。   The noise removing unit 25a removes noise components included in the detection results of the three-axis magnetic sensors 11, 12, and 13. Specifically, the noise removing unit 25a performs an averaging process on a plurality of detection results obtained from each of the three-axis magnetic sensors 11, 12, and 13 every predetermined period (for example, 1 second). Alternatively, noise components included in the detection results of the three-axis magnetic sensors 11, 12, and 13 are removed by separately performing the square sum square root process. Although the triaxial detection results are output from the triaxial magnetic sensors 11, 12, and 13, the noise removal unit 25a removes the noise components individually for the detection results of the respective axes. Such noise removal is performed to improve the SN ratio (signal-to-noise ratio) of the three-axis magnetic sensors 11, 12, and 13 and increase the measurement accuracy of the current I.

磁界推定部２５ｂは、三軸磁気センサ１１，１２，１３の検出結果と三軸磁気センサ１１，１２，１３の位置関係とを用いて、被測定導体ＭＣ２に流れる電流によって生成される磁界を推定する。このような推定を行うのは、被測定導体ＭＣ２に流れる電流Ｉによって生成される磁界の影響を排除して、被測定導体ＭＣ１に流れる電流Ｉの測定精度を高めるためである。尚、磁界推定部２５ｂによって推定される磁界は、被測定導体ＭＣ２に流れる電流によって生成される磁界が、三軸磁気センサ１１，１２，１３に近似的に均一に作用するとみなした場合の磁界である。このような均一な磁界を考慮するのは、磁界推定部２５ｂの演算負荷の削減及び演算時間の短縮を図りつつ、可能な限り測定精度を高めるためである。尚、磁界推定部２５ｂで行われる処理の詳細については後述する。   The magnetic field estimation unit 25b estimates the magnetic field generated by the current flowing through the conductor to be measured MC2, using the detection results of the triaxial magnetic sensors 11, 12, and 13 and the positional relationship of the triaxial magnetic sensors 11, 12, and 13. To do. The reason for this estimation is to eliminate the influence of the magnetic field generated by the current I flowing through the conductor to be measured MC2 and to increase the measurement accuracy of the current I flowing through the conductor to be measured MC1. The magnetic field estimated by the magnetic field estimation unit 25b is a magnetic field when it is assumed that the magnetic field generated by the current flowing through the conductor to be measured MC2 acts approximately uniformly on the three-axis magnetic sensors 11, 12, and 13. is there. The reason for considering such a uniform magnetic field is to increase the measurement accuracy as much as possible while reducing the calculation load of the magnetic field estimation unit 25b and the calculation time. Details of the processing performed by the magnetic field estimation unit 25b will be described later.

距離推定部２５ｃは、三軸磁気センサ１１，１２，１３の検出結果と三軸磁気センサ１１，１２，１３の位置関係とを用いて、被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３の少なくとも１つの距離を推定する。このような距離の推定を行うのは、被測定導体ＭＣ１に流れる電流Ｉを測定するためである。尚、距離推定部２５ｃで行われる処理の詳細については後述する。   The distance estimation unit 25c uses the detection results of the triaxial magnetic sensors 11, 12, 13 and the positional relationship of the triaxial magnetic sensors 11, 12, 13, and the triaxial magnetic sensors 11, 12, 13 with respect to the conductor MC1 to be measured. At least one distance is estimated. The reason for estimating the distance is to measure the current I flowing through the conductor to be measured MC1. Details of the processing performed by the distance estimation unit 25c will be described later.

電流算出部２５ｄは、距離推定部２５ｃによって推定された距離と、被測定導体ＭＣ２に流れる電流Ｉによって生成される磁界の影響が排除された三軸磁気センサ１１，１２，１３の検出結果から、被測定導体ＭＣ１に流れる電流Ｉを求める。例えば、被測定導体ＭＣ１に対する三軸磁気センサ１１の距離が電流算出部２５ｄによって推定されたとすると、電流算出部２５ｄは、推定された三軸磁気センサ１１の距離と、三軸磁気センサ１１の検出結果から磁界推定部２５ｂによって推定された磁界を差し引いたものとに基づいて、被測定導体ＭＣ１に流れる電流Ｉを求める。尚、電流算出部２５ｄで行われる処理の詳細については後述する。   From the detection result of the triaxial magnetic sensors 11, 12, 13 from which the influence of the magnetic field generated by the distance estimated by the distance estimating unit 25c and the current I flowing through the conductor to be measured MC2 is eliminated, The current I flowing through the conductor to be measured MC1 is obtained. For example, if the distance of the triaxial magnetic sensor 11 with respect to the conductor to be measured MC1 is estimated by the current calculation unit 25d, the current calculation unit 25d detects the estimated distance of the triaxial magnetic sensor 11 and the detection of the triaxial magnetic sensor 11. Based on the result obtained by subtracting the magnetic field estimated by the magnetic field estimation unit 25b, the current I flowing through the conductor to be measured MC1 is obtained. Details of the processing performed by the current calculation unit 25d will be described later.

ここで、図１，図２に示す通り、回路部２０は、センサヘッド１０と分離されており、ケーブルＣＢを介してセンサヘッド１０に接続されている。このような構成にすることで、磁界検出機能（三軸磁気センサ１１，１２，１３）と演算機能（演算部２５）とを分離することができ、演算部２５がセンサヘッド１０内に設けられている場合に生ずる諸問題（例えば、温度特性、絶縁耐性）等を回避することができ、これにより電流測定装置１の用途を拡げることができる。   Here, as shown in FIGS. 1 and 2, the circuit unit 20 is separated from the sensor head 10 and is connected to the sensor head 10 via the cable CB. With this configuration, the magnetic field detection function (triaxial magnetic sensors 11, 12, 13) and the calculation function (calculation unit 25) can be separated, and the calculation unit 25 is provided in the sensor head 10. Thus, various problems (for example, temperature characteristics, insulation resistance) and the like that occur can be avoided, and the application of the current measuring device 1 can be expanded.

〈電流の測定原理〉
次に、電流測定装置１による電流の測定原理について説明する。図３は、本発明の一実施形態による電流測定装置による電流の測定原理を説明するための図である。まず、図３に示す通り、センサヘッド１０のみに係る座標系（ｘｙｚ直交座標系）と、被測定導体ＭＣ１，ＭＣ２に係る座標系（ＸＹＺ直交座標系）との２つの座標系を設定する。 <Current measurement principle>
Next, the principle of current measurement by the current measuring device 1 will be described. FIG. 3 is a diagram for explaining the principle of current measurement by the current measuring device according to the embodiment of the present invention. First, as shown in FIG. 3, two coordinate systems are set: a coordinate system related to only the sensor head 10 (xyz orthogonal coordinate system) and a coordinate system related to the conductors MC1 and MC2 (XYZ orthogonal coordinate system).

ｘｙｚ直交座標系は、センサヘッド１０の位置及び姿勢に応じて規定される座標系である。このｘｙｚ直交座標系は、三軸磁気センサ１１の位置に原点が設定されており、三軸磁気センサ１１，１２，１３の第１軸方向（三軸磁気センサ１１，１２の配列方向）にｘ軸が設定されており、三軸磁気センサ１１，１２，１３の第２軸方向にｙ軸が設定されており、三軸磁気センサ１１，１２，１３の第３軸方向（三軸磁気センサ１１，１３の配列方向）にｚ軸が設定されている。   The xyz orthogonal coordinate system is a coordinate system defined according to the position and orientation of the sensor head 10. In this xyz orthogonal coordinate system, the origin is set at the position of the three-axis magnetic sensor 11, and x in the first axis direction of the three-axis magnetic sensors 11, 12, 13 (the arrangement direction of the three-axis magnetic sensors 11, 12). The axis is set, the y-axis is set in the second axis direction of the triaxial magnetic sensors 11, 12, and 13, and the third axis direction of the triaxial magnetic sensors 11, 12, and 13 (the triaxial magnetic sensor 11 is set) , 13), the z-axis is set.

ここで、三軸磁気センサ１１，１２，１３の位置をＰｉ（ｉ＝１，２，３）として表す。尚、Ｐｉはベクトルである。つまり、三軸磁気センサ１１の位置をＰ１で表し、三軸磁気センサ１２の位置をＰ２で表し、三軸磁気センサ１３の位置をＰ３で表すとする。例えば、図３に示す通り、三軸磁気センサ１１，１２のｘ方向の間隔、及び三軸磁気センサ１１，１３のｚ方向の間隔がｄ［ｍ］であるとすると、三軸磁気センサ１１，１２，１３の位置は以下の通りに表される。
三軸磁気センサ１１の位置：Ｐ１＝（０，０，０）
三軸磁気センサ１２の位置：Ｐ２＝（ｄ，０，０）
三軸磁気センサ１３の位置：Ｐ３＝（０，０，ｄ） Here, the positions of the three-axis magnetic sensors 11, 12, 13 are represented as Pi (i = 1, 2, 3). Pi is a vector. That is, the position of the triaxial magnetic sensor 11 is represented by P1, the position of the triaxial magnetic sensor 12 is represented by P2, and the position of the triaxial magnetic sensor 13 is represented by P3. For example, as shown in FIG. 3, assuming that the distance in the x direction of the triaxial magnetic sensors 11 and 12 and the distance in the z direction of the triaxial magnetic sensors 11 and 13 are d [m], The positions of 12 and 13 are expressed as follows.
Position of the triaxial magnetic sensor 11: P1 = (0, 0, 0)
Position of the triaxial magnetic sensor 12: P2 = (d, 0, 0)
Position of the triaxial magnetic sensor 13: P3 = (0, 0, d)

ＸＹＺ座標系は、被測定導体ＭＣ１，ＭＣ２に応じて規定される座標系である。このＸＹＺ直交座標系は、被測定導体ＭＣ１，ＭＣ２の長手方向（電流Ｉの方向）にＸ軸が設定されており、被測定導体ＭＣ１，ＭＣ２の並び方向にＹ軸が設定されている。Ｚ軸は、Ｘ軸及びＹ軸に直交する方向に設定される。尚、ＸＹＺ直交座標系の原点位置は、任意の位置に設定可能である。   The XYZ coordinate system is a coordinate system defined according to the conductors MC1 and MC2 to be measured. In this XYZ orthogonal coordinate system, the X axis is set in the longitudinal direction (direction of current I) of the conductors MC1 and MC2 to be measured, and the Y axis is set in the direction in which the conductors MC1 and MC2 are to be measured. The Z axis is set in a direction orthogonal to the X axis and the Y axis. The origin position of the XYZ orthogonal coordinate system can be set to an arbitrary position.

図３に示す通り、被測定導体ＭＣ１に対する三軸磁気センサ１１の距離をｒ１とし、被測定導体ＭＣ１に対する三軸磁気センサ１２の距離をｒ２とし、被測定導体ＭＣ１に対する三軸磁気センサ１３の距離をｒ３とする、尚、距離ｒ１は、三軸磁気センサ１１から被測定導体ＭＣ１に垂直に下ろした線分の長さであり、距離ｒ２は、三軸磁気センサ１２から被測定導体ＭＣ１に垂直に下ろした線分の長さであり、距離ｒ３は、三軸磁気センサ１３から被測定導体ＭＣ１に垂直に下ろした線分の長さである。尚、距離ｒ１，ｒ２，ｒ３は、検出できない点に注意されたい。   As shown in FIG. 3, the distance of the triaxial magnetic sensor 11 to the conductor to be measured MC1 is r1, the distance of the triaxial magnetic sensor 12 to the conductor to be measured MC1 is r2, and the distance of the triaxial magnetic sensor 13 to the conductor to be measured MC1. Where r3 is the length of the line segment perpendicularly drawn from the triaxial magnetic sensor 11 to the conductor to be measured MC1, and the distance r2 is perpendicular to the conductor to be measured MC1 from the triaxial magnetic sensor 12. The distance r3 is the length of the line segment dropped from the triaxial magnetic sensor 13 perpendicularly to the conductor to be measured MC1. Note that the distances r1, r2, and r3 cannot be detected.

また、被測定導体ＭＣ１に流れる電流Ｉによって三軸磁気センサ１１，１２，１３の位置に形成される磁界をＨＡｉ（ｉ＝１，２，３）として表す。尚、ＨＡｉはベクトルである。つまり、被測定導体ＭＣ１に流れる電流Ｉによって三軸磁気センサ１１の位置に形成される磁界をＨＡ１として表し、被測定導体ＭＣ１に流れる電流Ｉによって三軸磁気センサ１２の位置に形成される磁界をＨＡ２として表し、被測定導体ＭＣ１に流れる電流Ｉによって三軸磁気センサ１３の位置に形成される磁界をＨＡ３として表す。 Further, the magnetic field formed at the position of the three-axis magnetic sensor 11, 12, 13 by the current I flowing through the conductor to be measured MC1 is represented as H Ai (i = 1, 2, 3). Note that H Ai is a vector. That represents the magnetic field formed at the position of the three-axis magnetic sensor 11 by a current I flowing through the measured conductor MC1 as H A1, the magnetic field formed at the position of the three-axis magnetic sensor 12 by a current I flowing through the measured conductor MC1 Is represented as H A2 , and the magnetic field formed at the position of the three-axis magnetic sensor 13 by the current I flowing through the conductor to be measured MC1 is represented as H A3 .

また、被測定導体ＭＣ２に対するセンサヘッド１０の距離が、被測定導体ＭＣ１に対するセンサヘッド１０の距離に比べて十分大きいとすると、被測定導体ＭＣ２に流れる電流Ｉによって形成される磁界は、三軸磁気センサ１１，１２，１３に近似的に均一に作用するとみなすことができる。この磁界をＨＢとして表す。尚、ＨＢはベクトルである。すると、被測定導体ＭＣ１，ＭＣ２に流れる電流Ｉによって三軸磁気センサ１１，１２，１３の位置に形成される磁界Ｈｉ（ｉ＝１，２，３）は、以下の（１）式によって表される。尚、Ｈｉはベクトルである。

Figure 2019152607
If the distance of the sensor head 10 with respect to the conductor to be measured MC2 is sufficiently larger than the distance of the sensor head 10 with respect to the conductor to be measured MC1, the magnetic field formed by the current I flowing through the conductor to be measured MC2 is triaxial magnetic. It can be considered that the sensor 11, 12, 13 acts approximately uniformly. The magnetic field expressed as H B. H B is a vector. Then, the magnetic field Hi (i = 1, 2, 3) formed at the position of the three-axis magnetic sensor 11, 12, 13 by the current I flowing through the conductors MC1 and MC2 is expressed by the following equation (1). The Hi is a vector.
Figure 2019152607

次に、センサヘッド１０のみに係るｘｙｚ直交座標系と、被測定導体ＭＣ１，ＭＣ２に係るＸＹＺ直交座標系とを関連付けるために、電流Ｉの方向（図３中のＸ軸の方向）を求める。前述の通り、被測定導体ＭＣ２に流れる電流Ｉによって形成される磁界ＨＢを均一と近似しているため、三軸磁気センサ１１，１２，１３の検出結果の差分をとると磁界ＨＢをキャンセルすることができる。また、電流Ｉの方向は、磁界の方向と直交するため、三軸磁気センサ１１，１２，１３の検出結果の差分の外積の方向は、電流Ｉの方向と一致する。このため、電流Ｉの方向（図３中のＸ軸の方向）の単位ベクトルｊは、三軸磁気センサ１１，１２，１３の検出結果（磁界Ｈ１，Ｈ２，Ｈ３）を用いて、以下の（２）式で表される。 Next, in order to associate the xyz orthogonal coordinate system relating only to the sensor head 10 and the XYZ orthogonal coordinate system relating to the conductors MC1 and MC2 to be measured, the direction of the current I (the direction of the X axis in FIG. 3) is obtained. As described above, since the magnetic field H B formed by the current I flowing through the conductor to be measured MC2 is approximated to be uniform, the magnetic field H B is canceled when the difference between the detection results of the three-axis magnetic sensors 11, 12, 13 is taken. can do. Further, since the direction of the current I is orthogonal to the direction of the magnetic field, the direction of the outer product of the difference between the detection results of the three-axis magnetic sensors 11, 12, 13 coincides with the direction of the current I. For this reason, the unit vector j in the direction of the current I (the direction of the X axis in FIG. 3) uses the detection results (magnetic fields H1, H2, H3) of the triaxial magnetic sensors 11, 12, and 13 as follows: 2) It is expressed by the formula.

Figure 2019152607
Figure 2019152607

次いで、ｘｙｚ直交座標系で表された各種ベクトルをＸＹＺ直交座標系で表すために、図４に示す通り、電流Ｉに対して垂直な平面Γを考える。つまり、上記（２）式を用いて求められる単位ベクトルｊに垂直な平面Γを考える。尚、平面Γは、ＹＺ平面に平行な平面であるということもできる。図４は、被測定導体及び三軸磁気センサを、図３中の方向Ｄ１から見た図である。図３中の方向Ｄ１は、被測定導体ＭＣ１，ＭＣ２の長手方向に沿う方向（被測定導体ＭＣ１に流れる電流Ｉの方向とは反対の方向、被測定導体ＭＣ２に流れる電流Ｉの方向に沿う方向）である。尚、図４においては、理解を容易にするためにセンサヘッド１０の図示を省略して、被測定導体ＭＣ１，ＭＣ２及び三軸磁気センサ１１，１２，１３を図示している。   Next, a plane Γ perpendicular to the current I is considered as shown in FIG. 4 in order to represent various vectors represented in the xyz orthogonal coordinate system in the XYZ orthogonal coordinate system. That is, a plane Γ perpendicular to the unit vector j obtained using the above equation (2) is considered. It can be said that the plane Γ is a plane parallel to the YZ plane. FIG. 4 is a view of the conductor to be measured and the three-axis magnetic sensor as viewed from the direction D1 in FIG. A direction D1 in FIG. 3 is a direction along the longitudinal direction of the conductors to be measured MC1 and MC2 (a direction opposite to the direction of the current I flowing through the conductor to be measured MC1, a direction along the direction of the current I flowing through the conductor to be measured MC2) ). In FIG. 4, for the sake of easy understanding, illustration of the sensor head 10 is omitted, and the conductors MC1 and MC2 to be measured and the three-axis magnetic sensors 11, 12, and 13 are illustrated.

図４に示す平面Γに対して、被測定導体ＭＣ１，ＭＣ２、三軸磁気センサ１１，１２，１３、及び三軸磁気センサ１１，１２，１３の位置に形成される磁界を射影することにより、ｘｙｚ直交座標系で表された各種ベクトルをＸＹＺ直交座標系で表す。図４に示す通り、紙面に対して垂直なＸ方向（±Ｘ方向）に流れる電流Ｉによって、三軸磁気センサ１１，１２，１３の位置に形成される磁界は、Ｘ軸に直交するものになる。従って、電流Ｉが流れる方向と直交する平面Γに、三軸磁気センサ１１，１２，１３の位置に形成される磁界を、その大きさを変えることなく射影することができる。   By projecting the magnetic fields formed at the positions of the conductors to be measured MC1, MC2, the triaxial magnetic sensors 11, 12, 13 and the triaxial magnetic sensors 11, 12, 13 on the plane Γ shown in FIG. Various vectors represented in the xyz rectangular coordinate system are represented in the XYZ rectangular coordinate system. As shown in FIG. 4, the magnetic field formed at the positions of the three-axis magnetic sensors 11, 12, and 13 by the current I flowing in the X direction (± X direction) perpendicular to the paper surface is perpendicular to the X axis. Become. Therefore, the magnetic field formed at the position of the three-axis magnetic sensors 11, 12, 13 can be projected onto the plane Γ orthogonal to the direction in which the current I flows without changing the magnitude thereof.

ここで、平面Γ上における三軸磁気センサ１１，１２，１３の位置をｐｉ（ｉ＝１，２，３）として表し、平面Γ上における被測定導体ＭＣ１の位置をｐＡとして表す。尚、ｈｉ，ｐＡは、２次元のベクトルである。また、平面Γ上に射影された磁界ｈｉ（ｉ＝１，２，３）を、以下の（３）式で表す。以下の（３）式中のｈＡｉ，ｈＢはそれぞれ、上記（１）式中のＨＡｉ，ＨＢを平面Γに射影したものである。尚、ｈｉは２次元のベクトルである。

Figure 2019152607
Here, it represents the position of the three-axis magnetic sensor 11, 12 and 13 in the upper plane Γ as pi (i = 1,2,3), represents the position of the measured conductor MC1 in the upper plane Γ as p A. Hi and p A are two-dimensional vectors. The magnetic field hi (i = 1, 2, 3) projected on the plane Γ is expressed by the following equation (3). H Ai and h B in the following equation (3) are obtained by projecting H Ai and H B in the above equation (1) onto the plane Γ. Hi is a two-dimensional vector.
Figure 2019152607

続いて、被測定導体ＭＣ２に流れる電流Ｉによって形成される磁界ＨＢを推定する。まず、図４に示す通り、平面Γ上において、磁界ｈＡ１は、三軸磁気センサ１１から被測定導体ＭＣ１に垂直に下ろした線分に直交する。また、平面Γ上において、磁界ｈＡ２は、三軸磁気センサ１２から被測定導体ＭＣ１に垂直に下ろした線分に直交する。同様に、平面Γ上において、磁界ｈＡ３は、三軸磁気センサ１３から被測定導体ＭＣ１に垂直に下ろした線分に直交する。従って、これら線分を示すベクトルと磁界ｈＡ１，ｈＡ２，ｈＡ３との内積がゼロになるため、以下の（４）式が成り立つ。

Figure 2019152607
Subsequently, the magnetic field H B formed by the current I flowing through the conductor to be measured MC2 is estimated. First, as shown in FIG. 4, on the plane Γ, the magnetic field h A1 is orthogonal to a line segment perpendicularly dropped from the triaxial magnetic sensor 11 to the conductor to be measured MC1. In addition, on the plane Γ, the magnetic field h A2 is orthogonal to a line segment that extends perpendicularly from the triaxial magnetic sensor 12 to the conductor to be measured MC1. Similarly, on the plane Γ, the magnetic field h A3 is orthogonal to a line segment that extends perpendicularly from the triaxial magnetic sensor 13 to the conductor to be measured MC1. Therefore, the inner product of the vector indicating these line segments and the magnetic fields h A1 , h A2 , and h A3 becomes zero, and the following equation (4) holds.
Figure 2019152607

次に、上記線分の長さと、磁界ｈＡ１，ｈＡ２，ｈＡ３の大きさとの関係に着目すると、アンペールの法則から以下の（５）式が成り立つ。

Figure 2019152607
Next, paying attention to the relationship between the length of the line segment and the magnitudes of the magnetic fields h A1 , h A2 , and h A3 , the following equation (5) is established from Ampere's law.
Figure 2019152607

ここで、前述の通り、三軸磁気センサ１１，１２，１３から被測定導体ＭＣ１に垂直に下ろした線分を示すベクトルと磁界ｈＡ１，ｈＡ２，ｈＡ３との内積がゼロになるが、各々の線分を示すベクトルを平面Γ内で９０°回転させてから磁界ｈＡ１，ｈＡ２，ｈＡ３との内積をとると、以下の（６）式が成り立つ。

Figure 2019152607
Here, as described above, the inner product of the vector indicating the line segment perpendicular to the conductor MC1 to be measured from the three-axis magnetic sensors 11, 12, 13 and the magnetic fields h A1 , h A2 , h A3 becomes zero. When a vector indicating each line segment is rotated by 90 ° in the plane Γ and an inner product with the magnetic fields h A1 , h A2 , and h A3 is taken, the following equation (6) is established.
Figure 2019152607

但し、上記（６）式中のＲは、二次元座標平面内における９０°回転行列であり、以下の（７）式で示される。

Figure 2019152607
However, R in the above equation (6) is a 90 ° rotation matrix in the two-dimensional coordinate plane, and is represented by the following equation (7).
Figure 2019152607

平面Γに射影した磁界ｈＢは、上記（４），（６）式を用いて得られる以下の（８）式から求められる。

Figure 2019152607
The magnetic field h B projected onto the plane Γ is obtained from the following equation (8) obtained using the equations (4) and (6).
Figure 2019152607

但し、上記（８）式中のｐ，ｈ，ｃ１，ｃ２は、以下の（９）式に示される通りである。

Figure 2019152607
However, p, h, c 1 and c 2 in the above formula (8) are as shown in the following formula (9).
Figure 2019152607

ここで、被測定導体ＭＣ２に流れる電流Ｉによって形成される磁界ＨＢを平面Γに射影した磁界ｈＢは、Ｘ成分（電流Ｉが流れる方向の成分）が失われている。被測定導体ＭＣ１に流れる電流Ｉによって形成される磁界ＨＡｉは、Ｘ成分が生ずることはないため、被測定導体ＭＣ１，ＭＣ２に流れる電流Ｉによって形成される磁界ＨｉのＸ成分は、磁界ＨＢのＸ成分と等価になる。このため、磁界ＨｉのＸ成分（ｊＴＨｉ）を磁界ｈＢに追加することで、磁界ＨＢを求めることができる。このようにして、被測定導体ＭＣ２に流れる電流Ｉによって形成される磁界ＨＢを推定することができる。 Here, the magnetic field h B obtained by projecting the magnetic field H B formed by the current I flowing through the conductor to be measured MC2 onto the plane Γ loses the X component (the component in the direction in which the current I flows). Since the magnetic field H Ai formed by the current I flowing through the conductor to be measured MC1 does not generate an X component, the X component of the magnetic field Hi formed by the current I flowing through the conductors to be measured MC1 and MC2 is the magnetic field H B. Is equivalent to the X component. Therefore, the magnetic field H B can be obtained by adding the X component (j T Hi) of the magnetic field Hi to the magnetic field h B. In this way, it is possible to estimate the magnetic field H B which is formed by a current I flowing through the measured conductor MC2.

続いて、平面Γ上における被測定導体ＭＣ１の位置ｐＡを求める。被測定導体ＭＣ１の位置ｐＡは、上記（４），（６），（８）式を用いて得られる以下の（１０）式から求められる。

Figure 2019152607
Subsequently, the position p A of the conductor to be measured MC1 on the plane Γ is obtained. The position p A of the conductor to be measured MC1 is obtained from the following equation (10) obtained using the equations (4), (6), and (8).
Figure 2019152607

平面Γ上における被測定導体ＭＣ１の位置ｐＡが分かると、被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３距離ｒ１，ｒ２，ｒ３を求める（推定する）ことができる。そして、距離ｒ１，ｒ２，ｒ３を求める（推定する）ことができれば、以下に示す組み合わせの何れかを用いて、アンペールの法則から電流Ｉを測定することができる。
・距離ｒ１と三軸磁気センサ１１の検出結果（磁界Ｈ１）との組み合わせ
・距離ｒ２と三軸磁気センサ１２の検出結果（磁界Ｈ２）との組み合わせ
・距離ｒ３と三軸磁気センサ１３の検出結果（磁界Ｈ３）との組み合わせ If the position p A of the conductor to be measured MC1 on the plane Γ is known, the three-axis magnetic sensor 11, 12, 13 distances r1, r2, r3 with respect to the conductor to be measured MC1 can be obtained (estimated). If the distances r1, r2, and r3 can be obtained (estimated), the current I can be measured from Ampere's law using any of the combinations shown below.
-Combination of distance r1 and detection result (magnetic field H1) of triaxial magnetic sensor 11-Combination of distance r2 and detection result (magnetic field H2) of triaxial magnetic sensor 12-Detection result of distance r3 and triaxial magnetic sensor 13 Combination with (magnetic field H3)

具体的には、まず、三軸磁気センサ１１，１２，１３の検出結果（磁界Ｈｉ）から、上記（８）式等を用いて推定された磁界ＨＢを差し引き、被測定導体ＭＣ１に流れる電流Ｉによって三軸磁気センサ１１，１２，１３の位置に形成される磁界ＨＡｉを求める。そして、上記（９）式等を用いて被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３距離ｒ１，ｒ２，ｒ３が求められている。このため、以下の（１１）式を用いて、被測定導体ＭＣ１に流れる電流Ｉが求められる。

Figure 2019152607
Specifically, first, from the detection result of the three-axis magnetic sensor 11, 12, 13 (magnetic field Hi), subtracts the estimated magnetic field H B using the above (8) or the like, the current flowing through the measured conductor MC1 The magnetic field HAi formed at the positions of the three-axis magnetic sensors 11, 12, 13 by I is obtained. Then, the three-axis magnetic sensor 11, 12, 13 distance r1, r2, r3 with respect to the conductor MC1 to be measured is obtained using the above equation (9) and the like. For this reason, the electric current I which flows into to-be-measured conductor MC1 is calculated | required using the following (11) Formula.
Figure 2019152607

〈電流測定装置の動作〉
次に、電流測定装置１を用いて被測定導体ＭＣ１（往路）に流れる電流Ｉを測定する際の動作について説明する。まず、電流測定装置１のユーザは、被測定導体ＭＣ１に流れる電流Ｉを測定するために、センサヘッド１０を被測定導体ＭＣ１に近接配置させる。尚、被測定導体ＭＣ１に対するセンサヘッド１０の位置及び姿勢は任意である。但し、被測定導体ＭＣ２に対するセンサヘッド１０の距離が、被測定導体ＭＣ１に対するセンサヘッド１０の距離に比べて十分大きいとみなせる程度に、被測定導体ＭＣ１に対してセンサヘッド１０を近接配置させる必要がある。尚、被測定導体ＭＣ２が移動可能なものである場合には、被測定導体ＭＣ２に対するセンサヘッド１０の距離が、被測定導体ＭＣ１に対するセンサヘッド１０の距離に比べて十分大きいとみなせる程度に、被測定導体ＭＣ２を被測定導体ＭＣ１に対して遠方に配置させる。 <Operation of current measuring device>
Next, an operation when measuring the current I flowing through the conductor to be measured MC1 (outward path) using the current measuring device 1 will be described. First, the user of the current measuring device 1 places the sensor head 10 close to the conductor to be measured MC1 in order to measure the current I flowing through the conductor to be measured MC1. The position and posture of the sensor head 10 with respect to the conductor to be measured MC1 are arbitrary. However, it is necessary to dispose the sensor head 10 close to the conductor to be measured MC1 so that the distance of the sensor head 10 to the conductor to be measured MC2 can be regarded as sufficiently larger than the distance of the sensor head 10 to the conductor to be measured MC1. is there. When the conductor to be measured MC2 is movable, the distance to be measured is such that the distance of the sensor head 10 to the conductor to be measured MC2 is sufficiently larger than the distance of the sensor head 10 to the conductor to be measured MC1. The measurement conductor MC2 is disposed far from the conductor to be measured MC1.

図５は、本発明の一実施形態による電流測定装置の動作の概要を示すフローチャートである。図５に示すフローチャートは、例えば一定周期（例えば、１秒）で開始される。図５に示すフローチャートの処理が開始されると、まず三軸磁気センサ１１，１２，１３によって、被測定導体ＭＣ１，ＭＣ２に流れる電流Ｉによって形成される磁界が検出される（ステップＳ１１）。尚、三軸磁気センサ１１，１２，１３による磁界の検出は、例えば１秒間に１０００回程度行われる。次に、三軸磁気センサ１１，１２，１３の検出結果を示す検出データを、メモリ２３に蓄積する処理が、回路部２０の演算部２５によって行われる（ステップＳ１２）。   FIG. 5 is a flowchart showing an outline of the operation of the current measuring device according to the embodiment of the present invention. The flowchart shown in FIG. 5 is started at, for example, a constant cycle (for example, 1 second). When the processing of the flowchart shown in FIG. 5 is started, a magnetic field formed by the current I flowing through the conductors MC1 and MC2 to be measured is first detected by the three-axis magnetic sensors 11, 12, and 13 (step S11). The detection of the magnetic field by the triaxial magnetic sensors 11, 12, 13 is performed, for example, about 1000 times per second. Next, processing for accumulating detection data indicating the detection results of the triaxial magnetic sensors 11, 12, 13 in the memory 23 is performed by the arithmetic unit 25 of the circuit unit 20 (step S12).

次いで、検出データから雑音を除去する処理が、雑音除去部２５ａによって行われる（ステップＳ１３）。具体的には、メモリ２３に蓄積された検出データが雑音除去部２５ａに読み出され、読み出された検出データに対して平均化処理又は二乗和平方根処理が行われることで、検出データに含まれる雑音成分を除去する処理が行われる。尚、二乗和平方根処理を行うと符号が無くなるため、別途、符号の付加を行う。ここで、三軸磁気センサ１１，１２，１３からは、三軸の検出結果を出力する３種類の検出データがそれぞれ出力される。雑音除去部２５ａによる雑音成分の除去は、各軸の検出データに対して個別に行われる。   Next, a process for removing noise from the detected data is performed by the noise removing unit 25a (step S13). Specifically, the detection data stored in the memory 23 is read out to the noise removing unit 25a, and the detected data is included in the detection data by performing an averaging process or a square sum square process on the read detection data. A process for removing the noise component is performed. In addition, since a code | symbol will be lost if a square sum square root process is performed, a code | symbol is added separately. Here, the three-axis magnetic sensors 11, 12, and 13 each output three types of detection data for outputting the three-axis detection results. The removal of the noise component by the noise removing unit 25a is performed individually on the detection data of each axis.

続いて、被測定導体ＭＣ２（復路）に流れる電流Ｉによって形成される磁界ＨＢを推定する処理が、磁界推定部２５ｂによって行われる（ステップＳ１４）。尚、磁界推定部２５ｂによって推定される磁界ＨＢは、被測定導体ＭＣ２に流れる電流によって生成される磁界が、３つの三軸磁気センサ１１，１２，１３に近似的に均一に作用するとみなした場合の磁界である点に注意されたい。 Subsequently, the process of estimating the magnetic field H B which is formed by a current I flowing through the measured conductor MC2 (return) is performed by the magnetic field estimation unit 25b (step S14). Note that the magnetic field H B estimated by the magnetic field estimation unit 25b is considered that the magnetic field generated by the current flowing through the conductor to be measured MC2 acts approximately uniformly on the three triaxial magnetic sensors 11, 12, and 13. Note that the magnetic field in the case.

図６は、図５中のステップＳ１４の処理の詳細を示すフローチャートである。ステップＳ１４の処理が開始されと、まず、図６に示す通り、被測定導体ＭＣ１，ＭＣ２を流れる電流Ｉの方向を算出する処理が、磁界推定部２５ｂによって行われる（ステップＳ２１）。具体的には、三軸磁気センサ１１，１２，１３の検出結果を用いて、前述した（２）式に示される演算を行って、被測定導体ＭＣ１，ＭＣ２を流れる電流Ｉの方向を算出する処理が、磁界推定部２５ｂによって行われる。   FIG. 6 is a flowchart showing details of the process in step S14 in FIG. When the process of step S14 is started, first, as shown in FIG. 6, a process of calculating the direction of the current I flowing through the conductors to be measured MC1 and MC2 is performed by the magnetic field estimation unit 25b (step S21). Specifically, using the detection results of the three-axis magnetic sensors 11, 12, and 13, the calculation shown in the above-described equation (2) is performed to calculate the direction of the current I flowing through the conductors to be measured MC1 and MC2. Processing is performed by the magnetic field estimation unit 25b.

次に、被測定導体ＭＣ１，ＭＣ２、三軸磁気センサ１１，１２，１３、及び三軸磁気センサ１１，１２，１３で検出された磁界Ｈ１，Ｈ２，Ｈ３を電流Ｉに垂直な平面Γに射影する処理が、磁界推定部２５ｂによって行われる（ステップＳ２２）。尚、かかる処理によって、磁界Ｈ１，Ｈ２，Ｈ３を平面Γ上に射影した磁界ｈ１，ｈ２，ｈ３は、前述した（３）式を用いて表される。   Next, the measured conductors MC1, MC2, triaxial magnetic sensors 11, 12, 13, and magnetic fields H1, H2, H3 detected by the triaxial magnetic sensors 11, 12, 13 are projected onto a plane Γ perpendicular to the current I. The process to perform is performed by the magnetic field estimation unit 25b (step S22). The magnetic fields h1, h2, and h3 obtained by projecting the magnetic fields H1, H2, and H3 onto the plane Γ by such processing are expressed using the above-described equation (3).

そして、被測定導体ＭＣ２（復路）に流れる電流Ｉによって形成される磁界ＨＢを算出する処理が、磁界推定部２５ｂによって行われる（ステップＳ２３）。具体的には、前述した（８），（９）式を用いて磁界ｈＢを算出し、磁界ＨｉのＸ成分（ｊＴＨｉ）を磁界ｈＢに追加して磁界ＨＢを求める処理が、磁界推定部２５ｂによって行われる。このような処理により、被測定導体ＭＣ２（復路）に流れる電流Ｉによって形成される磁界ＨＢが推定される。 Then, the process of calculating the magnetic field H B which is formed by a current I flowing through the measured conductor MC2 (return) is performed by field estimation unit 25b (step S23). Specifically, the above-described (8), the processing for calculating the magnetic field h B, obtains the magnetic field H B by adding X component of the magnetic field Hi a (j T Hi) to the magnetic field h B using equation (9) This is performed by the magnetic field estimation unit 25b. By such processing, the magnetic field H B which is formed by a current I flowing through the measured conductor MC2 (return) is estimated.

続いて、被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３の距離ｒ１，ｒ２，ｒ３を推定する処理が、距離推定部２５ｃによって行われる（ステップＳ１５）。具体的には、まず、平面Γ上における三軸磁気センサ１１，１２，１３の位置ｐｉ、平面Γ上に射影された磁界ｈｉ、前述した（８），（９）式を用いて算出される磁界ｈＢを用い、前述した（１０）式に示される演算を行って、平面Γ上における被測定導体ＭＣ１の位置ｐＡを求める処理が、距離推定部２５ｃによって行われる。そして、平面Γ上における被測定導体ＭＣ１の位置ｐＡと、平面Γ上における三軸磁気センサ１１，１２，１３の位置ｐｉとから、被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３の距離ｒ１，ｒ２，ｒ３を推定する処理が、距離推定部２５ｃによって行われる。 Subsequently, processing for estimating the distances r1, r2, and r3 of the triaxial magnetic sensors 11, 12, and 13 with respect to the conductor to be measured MC1 is performed by the distance estimating unit 25c (step S15). Specifically, first, the position pi of the triaxial magnetic sensors 11, 12, and 13 on the plane Γ, the magnetic field hi projected on the plane Γ, and the above-described equations (8) and (9) are calculated. using a magnetic field h B, performs an operation shown in the above-mentioned (10), processing for obtaining the position p a of the measured conductor MC1 in the upper plane Γ is performed by the distance estimation unit 25c. Then, from the position p A of the measured conductor MC1 on the plane Γ and the position pi of the triaxial magnetic sensors 11, 12, 13 on the plane Γ, the triaxial magnetic sensors 11, 12, 13 of the measured conductor MC1 are measured. A process for estimating the distances r1, r2, and r3 is performed by the distance estimation unit 25c.

以上の処理が終了すると、被測定導体ＭＣ１（往路）に流れる電流Ｉを算出する処理が、演算部２５の電流算出部２５ｄによって行われる（ステップＳ１６）。具体的には、三軸磁気センサ１１，１２，１３の検出結果（磁界Ｈ１，Ｈ２，Ｈ３）、ステップＳ１４で推定された磁界ＨＢ、及びステップＳ１５で推定された距離ｒ１，ｒ２，ｒ３を用い、前述した（１１）式に示される演算を行って、被測定導体ＭＣ１に流れる電流Ｉを算出する処理が、演算部２５の電流算出部２５ｄによって行われる。 When the above process is completed, the process of calculating the current I flowing through the conductor to be measured MC1 (outward path) is performed by the current calculation unit 25d of the calculation unit 25 (step S16). Specifically, the detection results (magnetic fields H1, H2, and H3) of the three-axis magnetic sensors 11, 12, and 13, the magnetic field H B estimated in step S14, and the distances r1, r2, and r3 estimated in step S15 are used. The process of calculating the current I flowing through the conductor to be measured MC1 by performing the calculation shown in the above-described equation (11) is performed by the current calculation unit 25d of the calculation unit 25.

より具体的には、三軸磁気センサ１１，１２，１３の検出結果（磁界Ｈ１，Ｈ２，Ｈ３）からステップＳ１４で推定された磁界ＨＢを差し引いて、（１１）式中の磁界ＨＡｉ（被測定導体ＭＣ１に流れる電流Ｉによって三軸磁気センサ１１，１２，１３の位置に形成される磁界）を求める処理が行われる。そして、ステップＳ１５で推定された距離ｒ１，ｒ２，ｒ３と磁界ＨＡｉの大きさとを用いて（１１）式に示される演算が行われる。このようにして、被測定導体ＭＣ２に流れる電流Ｉによって形成される磁界の影響が排除された上で、被測定導体ＭＣ１に流れる電流Ｉが非接触で直接的に測定される。 More specifically, by subtracting the magnetic field H B estimated in step S14 from the detection results (magnetic fields H1, H2, H3) of the three-axis magnetic sensors 11, 12, 13, the magnetic field H Ai ( A process for obtaining a magnetic field formed at the positions of the three-axis magnetic sensors 11, 12, 13 by the current I flowing through the conductor to be measured MC1 is performed. The operation represented in it (11) using the magnitude of the distance r1, r2, r3 and a magnetic field H Ai estimated in step S15 is performed. In this way, the influence of the magnetic field formed by the current I flowing through the conductor to be measured MC2 is eliminated, and the current I flowing through the conductor to be measured MC1 is directly measured without contact.

以上の通り、本実施形態では、三軸磁気センサ１１，１２，１３の検出結果と、三軸磁気センサ１１，１２，１３の位置関係とを用いて、被測定導体ＭＣ２に流れる電流Ｉによって形成される磁界ＨＢを推定するとともに、被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３の距離ｒ１，ｒ２，ｒ３を推定している。そして、三軸磁気センサ１１，１２，１３の検出結果（磁界Ｈ１，Ｈ２，Ｈ３）から磁界ＨＢの影響を排除したものと、推定した距離ｒ１，ｒ２，ｒ３とを用いて、被測定導体ＭＣ１に流れる電流Ｉを測定するようにしている。ここで、本実施形態では、被測定導体ＭＣ１に対するセンサヘッド１０の位置及び姿勢は任意で良い。また、三軸磁気センサ１１，１２，１３の検出結果は、電流Ｉが直流電流であるか交流電流であるかに拘わらず得られる。このため、本実施形態では、柔軟な配置が可能であり、往復する電流経路の何れか一方（被測定導体ＭＣ１）に流れる直流電流及び低周波の交流電流を非接触で精度良く測定することができる。 As described above, in the present embodiment, the detection result of the triaxial magnetic sensors 11, 12, 13 and the positional relationship of the triaxial magnetic sensors 11, 12, 13 are formed by the current I flowing through the conductor to be measured MC2. with estimating the magnetic field H B is, estimates the distance r1, r2, r3 of the three-axis magnetic sensor 11, 12, 13 with respect to the measurement conductor MC1. Then, by using the detection result of the three-axis magnetic sensor 11, 12, 13 (magnetic field H1, H2, H3) as in which the influence of the magnetic field H B, the distance r1, r2, r3 estimated, measured conductor The current I flowing through MC1 is measured. Here, in the present embodiment, the position and orientation of the sensor head 10 with respect to the conductor to be measured MC1 may be arbitrary. The detection results of the triaxial magnetic sensors 11, 12, and 13 are obtained regardless of whether the current I is a direct current or an alternating current. For this reason, in this embodiment, flexible arrangement | positioning is possible and it can measure the direct current and low frequency alternating current which flow through either one of the current paths (measurement conductor MC1) to and from the reciprocating current accurately without contact. it can.

また、本実施形態では、三軸磁気センサ１１，１２，１３が設けられたセンサヘッド１０と、演算部２５が設けられた回路部２０とが分離されてケーブルＣＢによって接続されている。これにより、センサヘッド１０の取り回しが容易になり、例えば狭い場所へのセンサヘッド１０の設置も容易に行うことができるため、より柔軟な配置が可能である。   In the present embodiment, the sensor head 10 provided with the three-axis magnetic sensors 11, 12, and 13 and the circuit unit 20 provided with the calculation unit 25 are separated and connected by a cable CB. As a result, the sensor head 10 can be easily handled. For example, the sensor head 10 can be easily installed in a narrow place, so that a more flexible arrangement is possible.

尚、被測定導体ＭＣ１に流れる電流Ｉを測定する場合には、三軸磁気センサ１１，１２，１３の検出結果（磁界Ｈ１，Ｈ２，Ｈ３から磁界ＨＢの影響を排除したもの）と、推定された距離ｒ１，ｒ２，ｒ３とを全て用いる必要は必ずしも無い。以下の組み合わせの何れかを用いれば、被測定導体ＭＣ１に流れる電流Ｉを測定することができる。
・距離ｒ１と三軸磁気センサ１１の検出結果との組み合わせ
・距離ｒ２と三軸磁気センサ１２の検出結果との組み合わせ
・距離ｒ３と三軸磁気センサ１３の検出結果との組み合わせ Incidentally, in the case of measuring the current I flowing through the measured conductor MC1 includes a detection result of the three-axis magnetic sensor 11, 12, 13 (magnetic field H1, H2, H3 those in which the influence of the magnetic field H B from), the estimated It is not always necessary to use all the distances r1, r2, and r3. If any one of the following combinations is used, the current I flowing in the conductor to be measured MC1 can be measured.
-Combination of distance r1 and detection result of triaxial magnetic sensor 11-Combination of distance r2 and detection result of triaxial magnetic sensor 12-Combination of distance r3 and detection result of triaxial magnetic sensor 13

以上、本発明の一実施形態による電流測定装置について説明したが、本発明は上記実施形態に制限されることなく本発明の範囲内で自由に変更が可能である。例えば、上述した実施形態では、被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３の距離ｒ１，ｒ２，ｒ３を推定し、推定した距離ｒ１，ｒ２，ｒ３を用いて被測定導体ＭＣ１に流れる電流Ｉを測定する例について説明した。しかしながら、被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３の距離ｒ１，ｒ２，ｒ３を推定する必要は必ずしも無く、省略することが可能である。   The current measuring apparatus according to the embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be freely changed within the scope of the present invention. For example, in the above-described embodiment, the distances r1, r2, and r3 of the three-axis magnetic sensors 11, 12, and 13 with respect to the conductor to be measured MC1 are estimated, and the estimated currents r1, r2, and r3 are used to flow to the conductor to be measured MC1. An example of measuring the current I has been described. However, it is not always necessary to estimate the distances r1, r2, and r3 of the triaxial magnetic sensors 11, 12, and 13 with respect to the conductor to be measured MC1, and they can be omitted.

つまり、前述した（９），（１０）式を参照すると、平面Γ上における被測定導体ＭＣ１の位置ｐＡは、平面Γ上における三軸磁気センサ１１，１２，１３の位置ｐｉ、平面Γ上に射影された磁界ｈｉ、前述した（８），（９）式を用いて算出される磁界ｈＢを用いて求められる。このため、被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３の距離ｒｉ（ｒ１，ｒ２，ｒ３）も、上記の位置ｐＡ、上記の位置ｐｉ、及び上記の磁界ｈＢを用いて求めることができる。よって、予め三軸磁気センサ１１，１２，１３の距離ｒｉを求める式を求めて前述した（１１）式に代入すれば、（１１）式は、上記の位置ｐＡ、上記の位置ｐｉ、及び上記の磁界ｈＢと、ＨＡｉの大きさとを用いて電流Ｉを求める式に変形することができる。このため、被測定導体ＭＣ１に対する三軸磁気センサ１１，１２，１３の距離ｒｉを推定する処理は省略することが可能である。 That is, referring to the above-described equations (9) and (10), the position p A of the conductor MC1 to be measured on the plane Γ is the position pi of the triaxial magnetic sensors 11, 12, 13 on the plane Γ, and on the plane Γ. , And the magnetic field h B calculated using the above-described equations (8) and (9). Therefore, the distances ri (r1, r2, r3) of the triaxial magnetic sensors 11, 12, 13 with respect to the conductor to be measured MC1 are also obtained using the position p A , the position pi, and the magnetic field h B. be able to. Therefore, if an equation for obtaining the distance ri of the three-axis magnetic sensors 11, 12, and 13 is obtained in advance and substituted into the equation (11) described above, the equation (11) can be expressed as the position p A , the position pi, and Using the magnetic field h B and the magnitude of H Ai , the current I can be transformed into an equation. For this reason, it is possible to omit the process of estimating the distance ri of the triaxial magnetic sensors 11, 12, 13 with respect to the conductor to be measured MC1.

また、上述した実施形態では、三軸磁気センサ１１，１２が第１軸方向（ｘ軸方向）に間隔ｄ［ｍ］だけ離間し、三軸磁気センサ１１，１３が第３軸方向（ｚ軸方向）に間隔ｄ［ｍ］だけ離間している例について説明した。しかしながら、三軸磁気センサ１１，１２，１３は、各々の感磁方向が互いに平行になるように設定されていれば、相対的な位置関係は任意である。   Further, in the above-described embodiment, the triaxial magnetic sensors 11 and 12 are separated by a distance d [m] in the first axial direction (x-axis direction), and the triaxial magnetic sensors 11 and 13 are separated in the third axial direction (z-axis). The example in which the distance d [m] is spaced in the direction) has been described. However, the relative positional relationship of the triaxial magnetic sensors 11, 12, and 13 is arbitrary as long as the magnetic sensitive directions are set to be parallel to each other.

１ 電流測定装置
１０ センサヘッド
１１ 三軸磁気センサ
１２ 三軸磁気センサ
１３ 三軸磁気センサ
２０ 回路部
２５ 演算部
２５ａ 雑音除去部
２５ｂ 磁界推定部
２５ｃ 距離推定部
２５ｄ 電流算出部
Ｉ 電流
ＭＣ１ 被測定導体
ＭＣ２ 被測定導体 DESCRIPTION OF SYMBOLS 1 Current measuring apparatus 10 Sensor head 11 Three-axis magnetic sensor 12 Three-axis magnetic sensor 13 Three-axis magnetic sensor 20 Circuit part 25 Calculation part 25a Noise removal part 25b Magnetic field estimation part 25c Distance estimation part 25d Current calculation part I Current MC1 Measured conductor MC2 Conductor to be measured

Claims (7)

互いに反対方向に電流が流れる一対の被測定導体の何れか一方に流れる電流を測定する電流測定装置であって、
各々の感磁方向が互いに平行になるように、予め規定された位置関係をもって配置された３つの三軸磁気センサと、
前記３つの三軸磁気センサの検出結果と前記３つの三軸磁気センサの位置関係とに基づいて、前記被測定導体の何れか他方に流れる電流によって生成される磁界の影響を排除した上で、前記被測定導体の何れか一方に流れる電流を求める演算部と、
を備える電流測定装置。 A current measuring device for measuring a current flowing in any one of a pair of conductors to be measured, in which currents flow in opposite directions,
Three three-axis magnetic sensors arranged with a predetermined positional relationship so that the respective magnetic sensing directions are parallel to each other;
Based on the detection results of the three triaxial magnetic sensors and the positional relationship of the three triaxial magnetic sensors, after eliminating the influence of the magnetic field generated by the current flowing through one of the measured conductors, A calculation unit for obtaining a current flowing in any one of the conductors to be measured;
A current measuring device comprising: 前記演算部は、前記３つの三軸磁気センサの検出結果と前記３つの三軸磁気センサの位置関係とを用いて、前記被測定導体の何れか他方に流れる電流によって生成される磁界を推定する磁界推定部と、
前記３つの三軸磁気センサの検出結果と前記３つの三軸磁気センサの位置関係とを用いて、前記被測定導体の何れか一方に対する前記３つの三軸磁気センサの少なくとも１つの距離を推定する距離推定部と、
前記距離推定部によって推定された距離と、前記距離推定部によって距離が推定された三軸磁気センサの検出結果から前記磁界推定部によって推定された磁界を差し引いたものとに基づいて、前記被測定導体の何れか一方に流れる電流を求める電流算出部と、
を備える請求項１記載の電流測定装置。 The calculation unit estimates a magnetic field generated by a current flowing in one of the measured conductors using a detection result of the three triaxial magnetic sensors and a positional relationship of the three triaxial magnetic sensors. A magnetic field estimator;
Using the detection results of the three triaxial magnetic sensors and the positional relationship of the three triaxial magnetic sensors, at least one distance of the three triaxial magnetic sensors with respect to any one of the conductors to be measured is estimated. A distance estimator;
Based on the distance estimated by the distance estimator and the result of subtracting the magnetic field estimated by the magnetic field estimator from the detection result of the three-axis magnetic sensor whose distance is estimated by the distance estimator A current calculation unit for obtaining a current flowing through one of the conductors;
A current measuring device according to claim 1. 前記磁界推定部によって推定される磁界は、前記被測定導体の何れか他方に流れる電流によって生成される磁界が、前記３つの三軸磁気センサに近似的に均一に作用するとみなした場合の磁界である、請求項２記載の電流測定装置。   The magnetic field estimated by the magnetic field estimation unit is a magnetic field when it is assumed that the magnetic field generated by the current flowing through one of the measured conductors acts approximately uniformly on the three three-axis magnetic sensors. The current measuring device according to claim 2, wherein 前記演算部は、前記３つの三軸磁気センサの検出結果に含まれる雑音成分を除去する雑音除去部を更に備えており、
前記雑音除去部によって雑音成分が除去された前記３つの三軸磁気センサの検出結果を用いて前記被測定導体の何れか一方に流れる電流を求める、
請求項１から請求項３の何れか一項に記載の電流測定装置。 The arithmetic unit further includes a noise removing unit that removes a noise component included in the detection results of the three three-axis magnetic sensors,
Using the detection results of the three three-axis magnetic sensors from which noise components have been removed by the noise removing unit, a current flowing through any one of the conductors to be measured is obtained.
The current measuring device according to any one of claims 1 to 3. 前記雑音除去部は、予め規定された一定の期間毎に得られる、前記３つの三軸磁気センサの検出結果の各々に対し、平均化処理又は二乗和平方根処理を個別に行うことで、前記３つの三軸磁気センサの検出結果に含まれる雑音成分をそれぞれ除去する、請求項４記載の電流測定装置。   The noise removing unit individually performs an averaging process or a square sum square root process on each of the detection results of the three triaxial magnetic sensors, which are obtained every predetermined period, so that the 3 The current measuring device according to claim 4, wherein noise components included in the detection results of the three triaxial magnetic sensors are removed. 前記３つの三軸磁気センサを備えるセンサヘッドと、
前記演算部を備える回路部と、
を備える請求項１か請求項５の何れか一項に記載の電流測定装置。 A sensor head comprising the three triaxial magnetic sensors;
A circuit unit comprising the arithmetic unit;
The current measuring device according to claim 1, further comprising: 前記３つの三軸磁気センサの検出結果を示す信号は、ディジタル信号である、請求項１から請求項６の何れか一項に記載の電流測定装置。   The current measuring device according to any one of claims 1 to 6, wherein the signal indicating the detection result of the three three-axis magnetic sensors is a digital signal.
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