JP6421046B2 - Current measuring device - Google Patents

Description

  The present invention relates to a current measuring device that measures current using a magnetic sensor, and more particularly to a current measuring device that measures current flowing in a plurality of branch paths provided in a bus bar.

  As sensors that detect current using magnetism, for example, magnetic sensors such as current transformers, Hall elements, and GMR elements are known. Since the magnetic sensor detects the magnitude of the current based on the strength of the magnetic field generated around the current to be detected, if a magnetic field unrelated to the current to be detected exists, an error occurs in the detection result. In particular, when the currents of a plurality of current paths arranged close to each other are detected by a magnetic sensor, a magnetic field having a current different from that of the detection target tends to cause an error, and thus the detection result needs to be corrected.

  The following patent document describes a current detector that measures currents flowing through a plurality of conductors to be measured using a plurality of magnetoelectric transducers and corrects the measured current values of each magnetoelectric transducer using a neural network.

JP 2001-83188 A

  In the invention described in Patent Document 1, since a neural network is used for correcting the current measurement value, high calculation capability is required to perform accurate correction. In addition, when the neural network is not properly learned (overlearning or the like), a large correction error may occur depending on the input pattern.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a current measuring device capable of accurately correcting current measurement values of a plurality of current paths obtained by using a magnetic sensor with a simple configuration. There is.

The current measurement device according to the present invention includes a main trunk, at least one bus bar including a plurality of branch paths branched from the main trunk, a plurality of magnetic sensors provided in the plurality of branch paths, and the plurality of branches. And a calculation unit for calculating each measured value of the branch current flowing in the road. The calculation unit is configured to obtain a measured value of the branch current by the magnetic sensor provided in the one branch path in the one bus bar, downstream from a branch portion with the one branch path in the main of the one bus bar. Is corrected based on the current value of the main current flowing to the side and the detection values of the magnetic sensors provided in the plurality of other branch paths arranged in order from the next to the one branch path in the one bus bar.
According to the above configuration, a current that generates a magnetic field that flows relatively close to the magnetic sensor provided in the one branch path in the one bus bar and that is easily detected by the magnetic sensor (main current, Based on the branch current), the measured value of the branch current by the magnetic sensor is corrected. Therefore, a highly accurate current measurement value can be obtained with a simple configuration.

Preferably, the calculation unit detects a current value of the main current that flows downstream from the branch portion of the main trunk, and is a detection value of the magnetic sensor provided in the branch path that is located downstream of the branch portion. You may get based on.
According to said structure, since it is not necessary to provide the current sensor for measuring the said trunk current separately, a structure becomes simple.

  Preferably, the other plurality of branch paths in the one bus bar are a predetermined number or less of the branch paths arranged on the upstream side of the one branch path, and a predetermined number or less of the other branch paths arranged on the downstream side of the one branch path. Branching paths.

  Preferably, the calculation unit includes: a first correction component proportional to a current value of the main current that flows downstream from a branching portion of the one bus bar with the one branch path in the main of the one bus bar; The measurement value may be corrected based on a correction value obtained by adding a plurality of second correction components proportional to detection values of the magnetic sensors provided in the other plurality of branch paths.

In addition, the calculation unit calculates the branch current measured by the magnetic sensor provided in the one branch path in the one bus bar, and a branch portion between the main branch of the one bus bar and the one branch path. A current value of the main current flowing from the downstream side of the main bus, a detection value of the magnetic sensor provided in the plurality of other branch paths in the one bus bar, and the main of the bus bar adjacent to the one bus bar. A current value of the main current that flows downstream from a branch portion with the branch path closest to one branch path, and a plurality of the branch paths arranged in order including the closest branch path in the adjacent bus bar You may correct | amend based on the detected value of the said magnetic sensor provided.
According to the above configuration, not only the current flowing through the one bus bar (main current, branch current), but also the bus sensor adjacent to the one bus bar is relatively close to the magnetic sensor provided in the one branch path. Since the measurement value of the branch current by the magnetic sensor is corrected in consideration of the influence of the flowing main current and the branch current, a more accurate current measurement value can be obtained.

  Preferably, the other plurality of branch paths in the one bus bar are a predetermined number or less of the branch paths arranged on the upstream side of the one branch path, and a predetermined number or less of the other branch paths arranged on the downstream side of the one branch path. The plurality of branch paths in the adjacent bus bars are the closest branch path, and a predetermined number or less of branch paths arranged upstream of the closest branch path, and And a predetermined number or less of branch paths arranged on the downstream side of the closest branch path.

  Preferably, the calculation unit includes: a first correction component proportional to a current value of the main current that flows downstream from a branching portion of the one bus bar with the one branch path in the main of the one bus bar; A plurality of second correction components proportional to the detection values of the magnetic sensors provided in the other plurality of branch paths, and a downstream portion from a branch portion of the main branch of the adjacent bus bar with the nearest branch path A third correction component proportional to the current value of the main current that flows and a detection value of the magnetic sensor provided in the plurality of branch paths arranged in order including the closest branch path in the adjacent bus bar The measurement value may be corrected based on a correction value added with the plurality of fourth correction components.

Further, the calculation unit is downstream from a branch portion between the detected value of the magnetic sensor provided in the other plurality of branch paths in the one bus bar and the one branch path in the main of the one bus bar. The measurement value may be corrected based on the correction value obtained by further adding a plurality of fifth correction components proportional to the product of the main current flowing to the side and the square of the current value.
In this case, the calculation unit includes a detection value of the magnetic sensor provided in the other plurality of branch paths in the one bus bar, and a branch portion between the main branch of the one bus bar and the one branch path. The measurement value may be corrected based on the correction value obtained by further adding a plurality of sixth correction components proportional to the product of the main current flowing downstream.
According to said structure, since the error resulting from the nonlinearity of the said magnetic sensor is correct | amended, a more accurate electric current measurement value is obtained.

  According to the present invention, current measurement values of a plurality of current paths obtained using a magnetic sensor can be accurately corrected with a simple configuration.

It is a figure which shows an example of a structure of the electric current measurement apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the specific shape and arrangement | positioning of a bus bar and a magnetic sensor in the electric current measuring apparatus shown in FIG. It is a figure which shows an example of a structure of a magnetic sensor. It is the 1st figure which illustrated the trunk current used for calculation of the trunk correction component, and a correction coefficient. It is the 2nd figure which illustrated the trunk current used for calculation of the trunk correction component, and a correction coefficient. It is the 1st figure which illustrated the branch current used for calculation of a branch correction component, and a correction coefficient. It is the 2nd figure which illustrated the branch current used for calculation of a branch correction component, and a correction coefficient. It is a figure which shows that the component which changes nonlinearly according to the main current and the branch current of a non-measurement object is contained in the measurement error of a branch current. It is the 1st figure which illustrated the detection value and correction coefficient of the branch current used for calculation of a residual error correction component. It is the 2nd figure which illustrated the detection value and correction coefficient of the branch current used for calculation of a residual error correction component. It is a figure which shows the example of the data table in which the correction coefficient of the main | foundation correction | amendment component was registered. It is a figure which shows the example of the data table in which the correction coefficient of the branch correction component was registered. It is a figure which shows the example of the data table in which the correction coefficient of the residual error correction component was registered.

FIG. 1 is a diagram illustrating an example of a configuration of a current measuring device according to an embodiment of the present invention. The current measuring device shown in FIG. 1 is a device that measures the current flowing through each distribution destination in a single-phase three-wire distribution board, and includes bus bars 10Y, 10Z, and 10N, and magnetic sensors SY _{1 to} SY ₈ , SZ _1. To SZ ₈ and a calculation unit 20.

  The bus bars 10Y and 10Z are respectively connected to a single-phase three-wire power supply line to which a ground voltage is applied, and the bus bar 10N is connected to a ground line. A power supply voltage VL1 is applied between the bus bar 10Y and the bus bar 10N, and a power supply voltage VL2 is applied between the bus bar 10Z and the bus bar 10N.

Bus bar 10Y includes a main trunk TY, a branch passage _BY 1 _{~BY 8} of 8 branching from the trunk TY. The bus bar 10Z includes a main trunk TZ and eight branch paths BY _{1 to} BY ₈ that branch from the main trunk TZ.

FIG. 2 is a diagram illustrating an example of specific shapes and arrangements of the bus bars (10Y, 10Z, 10N) and the magnetic sensors (SY1 to SY8, SZ1 to SZ8), which are the main parts of the current measuring device illustrated in FIG. .
In the example of FIG. 2, the bus bar 10N, the main trunk TY of the bus bar 10Y, and the main trunk TZ of the bus bar 10Z are plate-like conductors (copper plates or the like) that extend in a straight line, and are arranged adjacent to each other in parallel. The The main trunk TY of the bus bar 10Y is located between the bus bar 10N and the main trunk TZ of the bus bar 10Z.

In the example of FIG. 2, the branch paths BY _{1 to} BY ₈ are arranged at equal intervals along the extending direction of the main trunk TY. The branch paths BZ _{1 to} BZ ₈ are arranged at equal intervals along the extending direction of the main trunk TZ, and the intervals are the same as the intervals of the branch paths BY _{1 to} BY ₈ .

The branch paths BY _{1 to} BY ₈ and the branch paths BZ _{1 to} BZ ₈ are positioned on the “downstream side” of the trunk (TY, TZ) as the suffix number increases. Here, the difference between the “upstream side” and the “downstream side” of the main trunk is determined by the magnitude relationship between the currents flowing through the main trunk at two positions across the branching portion with the branch path. That is, at two positions on the main trunk, the larger current is the “upstream side” and the smaller current is the “downstream side”.

As shown in FIG. 1, the branch portion with the branch path BY _n (n is an integer from 1 to 8) in the main trunk TY is closest to the branch section with the same number of branch paths BZ _n in the main trunk TZ.

The branch paths BY _{1 to} BY ₈ extend perpendicular to the extending direction of the main trunk TY. The branch paths BZ _{1 to} BZ ₈ extend perpendicular to the extending direction of the main trunk TZ. Further, the branch paths BY _{1 to} BY ₈ and the branch paths BZ _{1 to} BZ ₈ extend in parallel to the same plane.

In the branch paths BY _{1 to} BY ₈ and the branch paths BZ _{1 to} BZ ₈ , the extending direction with respect to the main trunk (TY, TZ) is reversed. In FIG. 2, the branch paths BY _{1 to} BY ₈ extend from the front to the back with respect to the main trunk TY, and the branch paths BZ _{1 to} BZ ₈ extend from the back to the front with respect to the main trunk TZ ( refer graph1). As a result, the magnetic sensor mounted on the branch path of one bus bar of the bus bar 10Y and the bus bar 10Z does not physically interfere with the branch path of the other bus bar, so the interval between the two bus bars (10Y, 10Z). Can be narrowed.

The magnetic sensor SY _n is provided in proximity to the branch passage BY _n, and outputs a detected value _{Y n} of the branch current IBY _n flowing through the branch passage BY _n. The magnetic sensor SZ _n is provided in proximity to the branch passage BZ _n, and outputs the detected value _{Z n} of the branch current IBZ _n flowing through the branch passage BZ _n.

FIG. 3 is a diagram illustrating an example of the configuration of the magnetic sensor (SY _n , SZ _n ).
The magnetic sensor (SY _n , SZ _n ) shown in FIG. 3 has a plurality of magnetoelectric conversion elements 30 (a magnetoresistive effect element such as a GMR element or a Hall element) disposed on a circuit board 31. Each magneto-electric transducer 30 is disposed in point symmetry around the center of symmetry of the branch passage BY _n. Preferably arranged symmetrically having parallel symmetry axes and the line perpendicular to both the extending direction with respect to the stretching direction and the branch passage BY _n for trunk TY. More preferably, the number of the magnetoelectric conversion elements 30 is four or more, and the magnetoelectric conversion elements 30 are arranged in line symmetry having a symmetry axis parallel to the extending direction with respect to the main trunk TY. The circuit board 31 has a rectangular shape as a whole, and a rectangular cutout is formed on one short side of the rectangle. Four magnetoelectric transducers 30 are arranged along two opposing edges in the rectangular cutout. A branch path (BY _n , BZ _n ) is located at the center of the rectangular cutout formed in the circuit board 31.

Each detection value output from the magnetic sensors SY _{1 to} SY ₈ and SZ _{1 to} SZ ₈ is input to the calculation unit 20 through a wiring (not shown).

Calculating unit 20 based on the detection value output from the magnetic sensor _SY 1 to SY ₈ and _{SZ 1 ~SZ 8 (Y 1 ~Y} 8, Z 1 ~Z 8), the branch passage _BY 1 _{~BY 8} and BZ measurements of the branch current flowing in the _{1 ~BZ 8} a _{(DY 1 ~DY 8, DZ 1} ~DZ 8) is calculated.

  The calculation unit 20 includes a computer that performs processing according to an instruction code of a program stored in a storage device, and a logic circuit that realizes a specific function. All of the processing of the calculation unit 20 may be realized based on a program in a computer, or a part or all of the processing may be realized by a dedicated logic circuit.

The measured value of the branch current IBY _n branch passage BY _n indicated by the detected value Y _n of the magnetic sensor SY _n, contains many error components due to the influence of the magnetic field generated by the branch current IBY _n other than the current to be measured Yes. The same applies to the measurement value of the branch current IBZ _n branch passage BZ _n indicated by the detected value _{Z n} of the magnetic sensor SZ _n. Therefore, calculation unit 20, in order to actually determine the values IBY _n and IBZ _n of current flowing through each branch passage BY _n and BZ _n accurately, the detection value of the magnetic sensors _{(SY n, SZ n) (} Y _n , Z _n ) is corrected to remove an error component with respect to the measured value of the branch current (IBY _n , IBZ _n ) indicated by

Calculating unit 20, a measurement value DZ _n branch current IBZ _n flowing through the measured value DY _n and the branch passage BZ _n branch current IBY _n flowing through the branch passage BY _n, respectively calculated by the following equation.

“RY _n ” in Expression (1-1) is a correction for removing an error in the measured value of the branch current IBY _n indicated by the detected value Y _n of the magnetic sensor SY _n provided in the branch path BY _n of the bus bar 10Y. Indicates the value. Further, “RZ _n ” in the expression (1-2) is for removing an error in the measured value of the branch current IBZ _n indicated by the detected value Z _n of the magnetic sensor SZ _n provided in the branch path BZ _n of the bus bar 10Z. The correction value is shown.
The correction values RY _n and RZ _n are each expressed by the following equations.

The correction value RY _n represented by the equation (2-1) is a sum of three correction components (main correction component KY _n , branch correction component LY _n , and residual error correction component MY _n ) having different properties. Similarly, the correction value RZ _n represented by the equation (2-2) is a sum of three correction components (main correction component KZ _n , branch correction component LZ _n , and residual error correction component MZ _n ) having different properties. It is.
Hereinafter, each correction component will be described in detail.

[Master correction components KY _n , KZ _n (error due to magnetic field of main current)]
The main trunk correction component (KY _n , KZ _n ) is a main current flowing through the main trunk (TY, TZ) at a position close to the branch path (BY _n , BZ _n ) through which the branch current (IBY _n , IBZ _n ) to be measured flows. The measurement error of the magnetic sensor (SY _n , SZ _n ) due to the magnetic field of (IT _n , ITZ _n ) is corrected.

First, a description will be given trunk correction component KY _n to correct the measurement errors of the magnetic sensor SY _n. FIG. 4 is a diagram illustrating the main current (ITy _n , ITZ _n ) and correction coefficients (α _T (n), β _T (n)) used for calculating the main correction component KY _n .

The main current ITY _n indicates a current that flows downstream from a branch portion with the branch path BY _n in the main trunk TY of the bus bar 10Y. Further, the main current ITZ _n indicates a current that flows downstream from a branch portion with the branch path BZ _n closest to the branch path BY _n in the main trunk TZ of the bus bar 10Z adjacent to the bus bar 10Y. That is, the main currents ITY _n and ITZ _n are currents that flow relatively close to the magnetic sensor SY _n in the main trunk (TY, TZ) of each bus bar (10Y, 10Z) and affect the measured value of the magnetic sensor SY _n. give.

The trunk correction component KY _n is expressed by the following equation using the trunk currents ITY _n and ITZ _n .

“Α _T (n)” and “β _T (n)” in Equation (3) are correction coefficients each having a constant value. These correction coefficients are determined for each branch path through which the branch current to be corrected flows, and are acquired based on the results of actual measurement or simulation, for example.

The first term “α _T (n) × ITY _n ” on the right side of Expression (3) is an example of the “first correction component” in the present invention. The second term on the right side “β _T (n) × ITZ _n ” is an example of the “third correction component” in the present invention.

As shown in Expression (3), the main correction component KY _n is adjacent to the bus bar 10Y and a component proportional to the main current ITY _n of the bus bar 10Y (“α _T (n) × ITY _n ”, the first correction component). component proportional to the trunk current ITZ _n bus bar 10Z of ( "β _{T (n)} × ITZ n", the third correction component) in which the sum of the.
The above is the description of the main trunk correction component KY _n.

Next, a description will be given trunk correction component KZ _n to correct the measurement errors of the magnetic sensor SZ _n. FIG. 5 is a diagram illustrating the main current (ITY _n , ITZ _n ) and correction coefficients (γ _T (n), η _T (n)) used for calculating the main correction component KZ _n .

The main currents ITY _n and ITZ _n shown in FIG. 5 are the same as the currents having the same signs shown in FIG. The main currents ITY _n and ITZ _n are currents that flow relatively close to the magnetic sensor SZ _n in the main trunk (TY, TZ) of each bus bar (10Y, 10Z), and affect the measured value of the magnetic sensor SZ _n. .

Senior correction component KZ _n is the main trunk current _ITY n, it represented using ITZ _n as follows.

“Γ _T (n)” and “η _T (n)” in Expression (4) are correction coefficients each having a constant value. These correction coefficients are determined for each branch path through which the branch current to be corrected flows, and are acquired based on the results of actual measurement or simulation, for example.

The first term “γ _T (n) × ITY _n ” on the right side of Expression (4) is an example of the “third correction component” in the present invention. Further, the second term “η _T (n) × ITZ _n ” on the right side is an example of the “first correction component” in the present invention.

As shown in the equation (4), the main correction component KZ _n is adjacent to the bus bar 10Z and a component proportional to the main current ITZ _n of the bus bar 10Z (“η _T (n) × ITZ _n ”, the first correction component). The component proportional to the main current ITY _n of the bus bar 10Y (“γ _T (n) × ITY _n ”, the third correction component) is added.
The above is the description of the main trunk correction component KZ _n.

Next, a method for obtaining the main currents ITY _n and ITZ _n will be described.
Trunk current ITY _n is the current flowing from the branch portion of the branch passage BY _n in trunk TY downstream, the branch passage _{(BY n + 1, BY n} + 2 located downstream from the branching portion of the branch passage BY _n, ... ) Is equal to the sum of branch currents (IBY _{n + 1} , IBY _{n + 2} ,. Thus, trunk current ITY _n is downstream of the branch passage _{(BY n + 1, BY n} + 2, ...) magnetic sensor provided in _{(SY n + 1, SY n} + 2, ...) detected value of _{(Y n + 1, Y n} + 2, ...) of It can be calculated approximately as the sum. The same applies to the trunk current ITZ _n, downstream of the branch passage _{(BZ n + 1, BZ n} + 2, ...) magnetic sensor provided in _{(SZ n + 1, SZ n} + 2, ...) detected value of _{(Z n + 1, Z n} + 2, ...) Can be approximately calculated as the sum of.

The approximate values of the trunk currents ITY _n and ITZ _n used for calculating the trunk correction components KY _n and KZ _{n in} the calculation unit 20 are expressed as the following equations.

Note that there is no branch path downstream of the branch paths BY ₈ and BZ _{8 of} the main trunks TY and TZ, and no current flows to the downstream side, so the main currents ITY ₈ and ITZ ₈ are zero.

[Branch correction components LY _n , LZ _n (error due to magnetic field of branch current)]
The branch correction component (LY _n , LZ _n ) corrects the measurement error of the magnetic sensor (SY _n , SZ _n ) caused by the magnetic field of another branch current different from the measurement target.

First, a description will be given branch correction component LY _n to correct the measurement errors of the magnetic sensor SY _n. FIG. 6 shows detected values (Y _{n−3 to} Y _n−1 , Y _{n + 1 to} Y _{n + 3} , Z _{n−3 to} Z _{n + 3} ) used for calculation of the branch correction component LY _n and the correction coefficient (α _{− 3} (n) to α ₋₁ (n), α ₊₁ (n) to α ₊₃ (n), β ₋₃ (n) to β ₊₃ (n)).

The detected values Y _{n-1 to} Y _{n- 3} of the branch current are three branch paths BY _{n-1 to} BY arranged on the upstream side of the branch path BY _n through which the branch current IBY _{n to} be measured of the magnetic sensor SY _n flows. It is a detection value of the magnetic sensors SY _{n-1 to} SY _n-3 provided in _n-3 . However, when “n” is 3 or less, the number of branch paths arranged on the upstream side of the branch path BY _n is 2 or less, and therefore, the upstream one of the three detection values Y _{n−1 to} Y _n−3. The above detection values do not exist.

The detected values Y _{n + 1 to} Y _{n + 3} of the branch currents are magnets provided in the _three branch paths BY _{n + 1 to} BY _{n +} 3 arranged on the downstream side of the branch path BY _n through which the branch current IBY _{n to} be measured of the magnetic sensor SY _n flows. The detection values of the sensors SY _{n + 1 to} SY _{n + 3} . However, when “n” is 6 or more, the number of branch paths arranged on the downstream side of the branch path BY _n is two or less, and therefore, one or more detection values on the downstream side of the _three detection values Y _{n + 1 to} Y _{n + 3.} Does not exist.

The detected value Z _n of the branch current is a detected value of the magnetic sensor SZ _n provided in the branch path BZ _n of the bus bar 10Z closest to the branch path BY _n through which the branch current IBY _{n to} be measured of the magnetic sensor SY _n flows. is there.

The branch current detection values Z _{n-1 to} Z _n-3 are provided in _three branch paths BZ _{n-1 to} BZ _n- 3 arranged on the upstream side of the branch path BZ _n closest to the branch path BY _n. The detected values of the magnetic sensors SZn _{-1 to} SZn _-3 . However, when “n” is 3 or less, the number of branch paths arranged on the upstream side of the branch path BZ _n is 2 or less, and therefore, one of the three detection values Z _{n−1 to} Z _{n−3 on} the upstream side. The above detection values do not exist.

Detected values _{Z n +} 1 _~Z n + ₃ of the branch current is branched three branch passages arranged in the downstream side of the passage BY _n closest to the branch passage _{BZ n BZ n + 1 ~BZ n} + magnetic sensor provided in the _{3 SZ n + 1 ~SZ n +} 3 Is the detected value. However, when “n” is 6 or more, the number of branch paths arranged on the downstream side of the branch path BZ _n is 2 or less, and therefore, one or more detection values on the downstream side of the _three detection values Z _{n + 1 to} Z _{n + 3.} Does not exist.

The branch correction component LY _n is expressed by the following equation using the detected values of these branch currents (Y _{n−3 to} Y _{n− 1} , Y _{n + 1 to} Y _{n + 3} , Z _{n−3 to} Z _{n + 3} ).

“Α ₋₃ (n)” to “α ₋₁ (n)”, “α ₊₁ (n)” to “α ₊₃ (n)”, and “β ₋₃ (n)” to “β” in Formula (6) _“+3 (n)” is a correction coefficient having a constant value. These correction coefficients are determined for each branch path through which the branch current to be corrected flows, and are acquired based on the results of actual measurement or simulation, for example. In the equation (6), when “n” is 3 or less or 6 or more, the term corresponding to the detected value of the branch current that does not exist is regarded as zero.

Each term from the first term “α ₋₁ (n) × Y _n−1 ” to the sixth term “α ₊₃ (n) × Y _{n + 3} ” of the right side of Expression (6) is the “second correction component of the present invention. Is an example. Each term from the seventh term “β ₋₁ (n) × Z _n−1 ” to the thirteenth term “β ₀ (n) × Z _n ” is an example of the “fourth correction component” in the present invention. It is.

As shown in Expression (6), the branch correction component LY _n is a correction component proportional to the branch current flowing in another branch path near the branch path BY _{n in} which the branch current IBY _{n to} be measured flows (formula ( Each item on the right side of 6) is added.
The above is the description of the branch correction component LY _n .

Next, a description will be given branch correction component LZ _n to correct the measurement errors of the magnetic sensor SZ _n. FIG. 7 shows detected values (Z _{n−3 to} Z _n−1 , Z _{n + 1 to} Z _{n + 3} , Y _{n−3 to} Y _{n + 3} ) and correction coefficients (η ₋ ) used for calculating the branch correction component LZ _{n. 3} (n) to η ₋₁ (n), η ₊₁ (n) to η ₊₃ (n), γ ₋₃ (n) to γ ₊₃ (n)).

The detected values Z _{n-1 to} Z _n-3 and Z _{n + 1 to} Z _{n + 3} of the branch current are supplied to the upstream and downstream branches of the branch path BZ _n through which the branch current IBZ _{n to} be measured by the magnetic sensor SZ _n flows. This is a detection value of the magnetic sensor provided, which is the same as the current of the same sign shown in FIG. When “n” is 3 or less, one or more detection values on the upstream side among the _three detection values Z _{n-1 to} Z _n-3 do not exist. When “n” is 6 or more, one or more detection values on the downstream side among the _three detection values Z _{n + 1 to} Z _{n + 3} do not exist.

The detected value Z _n of the branch current is a detected value of the magnetic sensor SY _n provided in the branch path BY _n of the bus bar 10Y closest to the branch path BZ _n through which the branch current IBZ _{n to} be measured of the magnetic sensor SZ _n flows. is there.

Detection value _{Y n-1 ~Y n-3} and _{Y n +} 1 _~Y n + ₃ of the branch current, the magnetic sensor provided on the branch passage on the upstream side and the downstream side of the branch passage BY _n closest to the branch passage BZ _n This is a detected value, which is the same as the current of the same sign shown in FIG. When “n” is 3 or less, one or more detection values on the upstream side among the _three detection values Y _{n−1 to} Y _n−3 do not exist. When “n” is 6 or more, one or more detection values on the downstream side among the _three detection values Y _{n + 1 to} Y _{n + 3} do not exist.

Branch correction component LZ _n is expressed by the following equation using the detection values of these branch current of _{(Z n-3 ~Z n-} 1, Z n + 1 ~Z n + 3, Y n-3 ~Y n + 3).

“Η ₋₃ (n)” to “η ₋₁ (n)”, “η ₊₁ (n)” to “η ₊₃ (n)”, and “γ ₋₃ (n)” to “γ” in Expression (7) _“+3 (n)” is a correction coefficient having a constant value. These correction coefficients are determined for each branch path through which the branch current to be corrected flows, and are acquired based on the results of actual measurement or simulation, for example. In equation (7), when “n” is 3 or less or 6 or more, the term corresponding to the non-existing branch current detection value is regarded as zero.

Each term from the eighth term “η ₋₁ (n) × Z _n−1 ” to the thirteenth term “η ₊₃ (n) × Z _{n + 3} ” of the right side of Expression (7) is the “second correction component of the present invention. Is an example. Each term from the first term “γ ₋₁ (n) × Y _n−1 ” to the seventh term “γ ₀ (n) × Y _n ” on the right side is an example of the “fourth correction component” in the present invention. Is

As shown in the equation (7), the branch correction component LZ _n is a correction component proportional to the branch current flowing in the other branch path near the branch path BZ _n through which the branch current IBZ _{n to} be measured flows (formula ( 7) Each item on the right side of 7) is added together.
The above is the description of the branch correction component LZ _n.

[Residual error correction components MY _n , MZ _n (error due to non-linearity of magnetic sensor)]
The residual error correction component (MY _n , MZ _n ) is a measurement error caused by the non-linearity of the magnetic sensor that cannot be removed by the main correction component (KY _n , KZ _n ) or the branch correction component (LY _n , ZY _n ). It is to correct.

FIG. 8 is a diagram showing that the branch current measurement error includes a component that changes nonlinearly according to the main current and the non-measurement target branch current.
The horizontal axis in the graph of FIG. 8 indicates the main current that flows downstream from the branch portion with the branch path through which the branch current to be measured flows. For example, if the branch current to be measured is “IBY _n ”, the main current on the horizontal axis is “ITY _n ”.
The vertical axis in the graph of FIG. 8 indicates the error included in the branch current measurement result. This error is an error that remains after the detection value of the magnetic sensor is corrected by the main correction component (KY _n , KZ _n ) and the branch correction component (LY _n , ZY _n ) described above. Specifically, the magnetic sensor The difference between the measured value obtained by correcting the detected value by the above-described trunk correction value and branch correction value and the actual current value is shown.

The residual error that cannot be removed by the main correction component (KY _n , KZ _n ) and the branch correction component (LY _n , ZY _n ) changes nonlinearly according to the main current ITY _n as shown in FIG. This residual error can be approximated as a quadratic function with the main correction value KY _n as a variable.

  Further, as shown in FIG. 8, the curve of the change in the residual error becomes steeper as the branch current to be measured becomes larger. Therefore, a value proportional to the branch current to be measured can be used as the coefficient of the quadratic function (particularly the coefficient of the quadratic term) representing the approximate expression of the residual error.

  The residual error of the magnetic sensor having nonlinear characteristics described above is mainly due to the fact that the response characteristics of the output of the magnetic sensor with respect to the magnetic field cannot maintain linearity (indicating nonlinearity) as the magnetic field increases.

Here, first, it will be described residual error correction component MY _n of the magnetic sensor SY _n. FIG. 9 shows detected values (Y _{n−3 to} Y _n−1 , Y _{n + 1 to} Y _{n + 3} ) and correction coefficients (A _{−3 to} A ₋₁ , A) used for calculating the residual error correction component MY _{n. 1 to} A ₃ , B _{−3 to} B ₋₁ , and B _{1 to} B ₃ ).

The detected values Y _{n-1 to} Y _{n- 3} and Y _{n + 1 to} Y _{n + 3} of the branch currents are supplied to the upstream and downstream branches of the branch path BY _n through which the branch current IBY _{n to} be measured by the magnetic sensor SY _n flows. This is the detected value of the magnetic sensor provided, and is the same as the current of the same sign shown in FIGS. When “n” is 3 or less, one or more detection values on the upstream side among the _three detection values Y _{n−1 to} Y _n−3 do not exist. When “n” is 6 or more, one or more detection values on the downstream side among the _three detection values Y _{n + 1 to} Y _{n + 3} do not exist.

Residual error correction component MY _n is represented detected values of the branch current and _{(Y n-1 ~Y n-} 3, Y n + 1 ~Y n + 3) by using the main trunk current ITY _n as follows.

In Formula (8), “A ₋₃ ” to “A ₋₁ ”, “A ₁ ” to “A ₃ ”, “B ₋₃ ” to “B ₋₁ ”, “B ₁ ” to “B ₃ ” are Each correction coefficient has a constant value. These correction coefficients are determined for each relative position of the upstream or downstream branch path as viewed from the branch path through which the branch current to be corrected flows, and are acquired based on, for example, the results of actual measurement or simulation. In equation (8), when “n” is 3 or less or 6 or more, the term corresponding to the detected value of the branch current that does not exist is regarded as zero. The main current ITY _n is acquired as a value obtained by adding the downstream branch current detection values by, for example, the equation (5-1).

The secondary term (odd-numbered term) of the main current ITY _{n on} the right side of the equation (8) is an example of the “fifth correction component” in the present invention. The primary term (even-numbered term) of the main current ITY _{n on} the right side is an example of the “sixth correction component” in the present invention.

As shown in Expression (8), the residual error correction component MY _n is composed of two terms (primary and secondary terms) having a coefficient proportional to the branch current, and a quadratic function of the main current ITY _n is expressed as follows. Contains more than one. That is, the first term and the second term, the third term and the fourth term, the fifth term and the sixth term, the seventh term and the eighth term, the ninth term and the tenth term on the right side of the equation (8), and The eleventh term and the twelfth term are quadratic functions composed of a primary term (sixth correction component) and a quadratic term (fifth correction component), respectively, of the main current ITY _n . The residual error correction component MY _n is obtained as a result of adding these quadratic functions. Each quadratic function indicates an error component due to the non-linearity of the magnetic sensor, and increases nonlinearly as the main current or branch current increases as shown in FIG.
The above is the description of the residual error correction component MY _n.

Next, a description will be given residual error correction component MZ _n of the magnetic sensor SZ _n. FIG. 10 shows detected values (Z _{n−3 to} Z _n−1 , Z _{n + 1 to} Z _{n + 3} ) and correction coefficients (C _{n−3 to} C _n−1 ) used for calculating the residual error correction component MZ _n. , C _{n + 1 to} C _{n + 3} , D _{n−3 to} D _n−1 , D _{n + 1 to} D _{n + 3} ).

The detected values Z _{n-1 to} Z _n-3 and Z _{n + 1 to} Z _{n + 3} of the branch current are supplied to the upstream and downstream branches of the branch path BZ _n through which the branch current IBZ _{n to} be measured by the magnetic sensor SZ _n flows. This is the detected value of the magnetic sensor provided, and is the same as the current of the same sign shown in FIGS. When “n” is 3 or less, one or more detection values on the upstream side among the _three detection values Z _{n-1 to} Z _n-3 do not exist. When “n” is 6 or more, one or more detection values on the downstream side among the _three detection values Z _{n + 1 to} Z _{n + 3} do not exist.

Residual error correction component MZ _n is represented detected values of the branch current and _{(Z n-1 ~Z n-} 3, Z n + 1 ~Z n + 3) by using the main trunk current ITZ _n as follows.

In Formula (9), “C ₋₃ ” to “C ₋₁ ”, “C ₁ ” to “C ₃ ”, “D ₋₃ ” to “D ₋₁ ”, “D ₁ ” to “D ₃ ” are Each correction coefficient has a constant value. These correction coefficients are determined for each relative position of the upstream or downstream branch path as viewed from the branch path through which the branch current to be corrected flows, and are acquired based on, for example, the results of actual measurement or simulation. In equation (9), when “n” is 3 or less or 6 or more, the term corresponding to the non-existing branch current detection value is regarded as zero. Trunk current ITZ _n, for example, by the formula (5-2) is obtained as a combined value plus the detection value of the downstream of the branch current.

Quadratic term main trunk current ITZ _n on the right-hand side of Equation (9) (odd-numbered term) is an example of the "fifth correction component" of the present invention. Also, first-order terms (even-numbered term) main trunk current ITZ _n on the right side is an example of the "sixth correction component" of the present invention.

As shown in the equation (9), the residual error correction component MZ _n has two terms (primary and quadratic terms) having a coefficient proportional to the branch current, as with the residual error correction component MY _n described above. It made), and includes a plurality of quadratic function of the trunk current ITZ _n. Residual error correction component MZ _n is obtained as a result of the sum of these quadratic function.
The above is the description of the residual error correction component MZ _n.

Next, the operation of the current detection device having the above-described configuration will be described.
The magnetic sensors (SY _n , SZ _n ) output detection values (Y _n , Z _n ) corresponding to the magnetic fields of the branch currents flowing through the branch paths, respectively. The calculation unit 20 includes, for example, an analog-digital converter, converts analog detection values output from each magnetic sensor into digital data, and stores the digital data in an internal storage device. Based on the detection values (Y _n , Z _n ) of each magnetic sensor stored in the storage device and the correction coefficients (FIGS. 11 to 13) registered in advance in the data table of the storage device, the calculation unit 20 The measured value (DY _n , DZ _n ) of the branch current flowing in the branch path is calculated.

FIG. 11 is a diagram illustrating an example of a data table in which correction coefficients for the main correction components (KY _n , KZ _n ) are registered. In the data table shown in FIG. 11, for each measurement value (DY _n , DZ _n ) calculated by the calculation unit 20, correction coefficients (α _T (n), β _T ) multiplied by the main current (ITY _n ) of the bus bar 10Y are calculated. (N)) and correction coefficients (γ _T (n), η _T (n)) to be multiplied by the main current (ITZ _n ) of the bus bar 10Z are registered.
The calculation unit 20 obtains the main correction component (KY _n , KZ _n ) using the correction coefficients registered in the data table according to the equations (3) and (4).

FIG. 12 is a diagram illustrating an example of a data table in which correction coefficients of branch correction components (LY _n , LZ _n ) are registered. In the data table shown in FIG. 12, for each measurement value (DY _n , DZ _n ) calculated by the calculation unit 20, a correction coefficient (α ₋₃ (n) multiplied by the detected value (Y _n ) of the branch current of the bus bar 10Y. ) To α ₋₁ (n), α ₊₁ (n) to α ₊₃ (n), γ ₋₃ (n) to γ ₊₃ (n)), and the detected value (Z _n ) of the branch current of the bus bar 10Z. Correction coefficients (β ₋₃ (n) to β ₋₁ (n), η ₊₁ (n) to η ₊₃ (n), η ₋₃ (n) to η ₊₃ (n)) are registered.
The calculation unit 20 obtains the branch correction components (LY _n , LZ _n ) using the correction coefficients registered in the data table according to the equations (6) and (7).

FIG. 13 is a diagram illustrating an example of a data table in which correction coefficients for residual error correction components (MY _n , MZ _n ) are registered. In the data table shown in FIG. 13, the correction coefficient (A ₋ ) multiplied by the secondary term of the main current for each relative position of the upstream or downstream branch path viewed from the branch path through which the branch current to be measured flows. _{3 to} A ₃ , C _{−3 to} C ₃ ) and correction coefficients (B _{−3 to} B ₃ , D _{−3 to} D ₃ ) to be multiplied by the primary term of the main current are registered.
The calculation unit 20 obtains the residual error correction components (MY _n , MZ _n ) by using the correction coefficients registered in the data table according to the equations (8) and (9).

The calculator 20 calculates a correction value (RY _n ) expressed as the sum of the main correction component (KY _n , KZ _n ), the branch correction component (LY _n , LZ _n ), and the residual error correction component (MY _n , MZ _n ). , RZ _n ) is subtracted from the detected value (Y _n , Z _n ) of the branch current, and the subtraction result is obtained as a measured value (DY _n , DZ _n ) of the branch current.

As described above, according to the current measuring device according to the present embodiment, the measured value (detected value Y _n ) of the branch current IBY _n by the magnetic sensor SY _n provided in the branch path BY _n of the bus bar 10Y is the bus bar. The current value of the main current ITY _n that flows downstream from the branch portion with the branch path BY _n in the main trunk TY of 10Y, and other branch paths (BY _n−) arranged in order from the next to the branch path BY _n in the bus bar 10Y. _{3 ~BY n-1, bY n} + 1 ~BY detection value of the magnetic sensor provided on the _{n + 3) (Y n-} 3 ~Y n-1, Y n + 1 ~Y n + 3) and on the basis the corrected.
Magnetic field trunk current flowing relatively close to the magnetic sensor SY _n (ITY _n) and branch currents _{(IBY n-3 ~IBY n-} 1, IBY n + 1 ~IBY n + 3) is likely to be detected in the magnetic sensor SY _n, branch prone to error of the measurement value of the current IBY _n. According to the present embodiment, the measurement value is corrected based on the surrounding current (main current, branch current) that is likely to cause an error in the measurement value of the branch current IBY _n . High current measurements can be obtained.

Further, according to the current measuring device according to the present embodiment, not only the current (main current, branch current) of the bus bar 10Y through which the branch current IBY _n flows, but also the branch path BY _n in the main TZ of the bus bar 10Z adjacent to the bus bar 10Y. the current value of the main trunk current ITZ _n flowing downstream from the branching portion between the closest branching path BZ _n, a plurality of branch paths arranged in a forward contain branch passage BZ _n in adjacent bus bar 10Z (BZ _n-3 The measured value of the branch current IBY _n is corrected based on the detection values (Z _{n−3 to} Z _{n + 3} ) of the magnetic sensor provided in .about.BZ _{n + 3} ).
As a result, the influence of the main current (ITZ _n ) and branch currents (IBY _{n−3 to} IBY _n−1 , IBY _{n + 1 to} IBY _{n + 3} ) flowing relatively close to the magnetic sensor SY _n in the adjacent bus bar 10Z is also taken into consideration. since the correction of the measured value of the branch current IBY _n is performed, it is possible to get a more accurate current measurements.

Furthermore, according to the current measuring device according to the present embodiment, the correction value RY _n for correcting the measured value of the branch current IBY _n, the residual error correction component MY _n is added. This residual error correction component MY _n is a sum of a plurality of quadratic functions of the main current ITY _n . Sections (1 order term, the second-order term) in the secondary function coefficients of the branch path plurality of branch paths arranged from the adjacent in this order _{BY n (BY n-3 ~BY} n-1, BY n + 1 ~BY _{n + 3} ) has a value proportional to a detection value (Yn _{-3 to} Yn _-1 , Yn _{+ 1 to} Yn _{+ 3} ) of the magnetic sensor provided at _{n + 3} ).
As a result, it is possible to correct an error caused by the nonlinearity of the magnetic sensor that tends to increase nonlinearly as the main current or the branch current increases, so that a more accurate current measurement value can be obtained.

Moreover, according to the current measurement device according to the present embodiment, when acquiring the current value of the main current ITY _n flowing downstream from the branch portion with the branch path BY _n in the main trunk TY, the downstream side of the branch portion. The detection values (Y _{n + 1} , Y _{n + 2} ,...) Of the magnetic sensor provided in the branch path (BY _{n + 1} , BY _{n + 2} ,. As a result, it is not necessary to separately provide a current sensor for measuring the main current ITY _n , so that the configuration can be simplified.

  In addition, this invention is not limited only to embodiment mentioned above, Various modifications are included.

  The shape, number, arrangement, and the like of the bus bars and branch paths in the above-described embodiments are examples, and can be arbitrarily changed. Further, the configuration of the magnetic sensor is not limited to the example of FIG. 3, and can be arbitrarily changed in accordance with the shape and arrangement of the branch path.

  In the above-described embodiment, an example in which the present invention is applied to a single-phase three-wire distribution board has been described. However, the present invention is not limited to this example, and various examples such as a three-layer three-wire system are available. It can also be applied to distribution type distribution boards. The present invention is not limited to distribution boards, and can be widely applied to devices that measure currents in a plurality of current paths in various electric devices, machines, vehicles, and the like.

10Y, 10Z ... busbar, 20 ... calculator, 30 ... electric _{transducer, SY 1 ~SY 8, SZ 1} ~SZ 8 ... magnetic sensor, TY, TZ ... _{trunk, BY 1 ~BY 8, BZ 1} ~BZ 8 ... Branch path, IBY _{1 to} IBY ₈ , IBZ _{1 to} IBZ ₈ ... Branch current, ITY _{1 to} ITY ₈ , ITZ _{1 to} ITZ ₈ ... Main current, Y _{1 to} Y ₈ , Z _{1 to} Z ₈ . , DY _{1 to} DY ₈ , DZ _{1 to} DZ ₈ ... measured values of branch current.

Claims (9)

At least one bus bar comprising a main trunk and a plurality of branch paths branched from the main trunk;
A plurality of magnetic sensors provided in the plurality of branch paths;
A calculation unit for calculating the measured values of branch currents flowing through the plurality of branch paths,
The calculation unit is configured to obtain a measured value of the branch current by the magnetic sensor provided in the one branch path in the one bus bar, downstream from a branch portion with the one branch path in the main of the one bus bar. Correction based on the current value of the main current flowing to the side and the detection values of the magnetic sensors provided in the plurality of other branch paths arranged in order from the next to the one branch path in the one bus bar. A current measuring device. The calculation unit calculates a current value of the main current flowing downstream from the branch portion of the main trunk based on a detection value of the magnetic sensor provided in the branch path located downstream from the branch portion. The current measuring device according to claim 1, wherein the current measuring device is acquired. The other plurality of branch paths in the one bus bar is:
A predetermined number or less of branch paths arranged upstream of the one branch path;
The current measuring device according to claim 2, further comprising a predetermined number or less of branch paths arranged on the downstream side of the one branch path. The calculation unit includes:
A first correction component proportional to a current value of the main current flowing downstream from a branch portion with the one branch path in the main of the one bus bar;
The measurement value is corrected based on a correction value obtained by adding a plurality of second correction components proportional to detection values of the magnetic sensors provided in the other plurality of branch paths in the one bus bar. The current measuring device according to claim 2 or 3. The calculation unit is configured to calculate a measured value of the branch current by the magnetic sensor provided in the one branch path in the one bus bar.
A current value of the main current that flows downstream from a branch portion with the one branch path in the main of the one bus bar;
Detection values of the magnetic sensors provided in the other plurality of branch paths in the one bus bar;
A current value of the main current that flows downstream from a branch portion of the main of the bus bar adjacent to the one bus bar and a branch path closest to the one branch path;
3. The current according to claim 2, wherein correction is performed based on detection values of the magnetic sensors provided in the plurality of branch paths arranged in order including the closest branch path in the adjacent bus bar. measuring device. The other plurality of branch paths in the one bus bar is:
A predetermined number or less of branch paths arranged upstream of the one branch path;
Including a predetermined number or less of branch paths arranged on the downstream side of the one branch path,
The plurality of branch paths in the adjacent bus bars are:
The nearest branch path;
A predetermined number or less of branch paths arranged on the upstream side of the nearest branch path;
The current measuring device according to claim 5, comprising: a predetermined number or less of branch paths arranged on the downstream side of the nearest branch path. The calculation unit includes:
A first correction component proportional to a current value of the main current flowing downstream from a branch portion with the one branch path in the main of the one bus bar;
A plurality of second correction components proportional to detection values of the magnetic sensors provided in the other plurality of branch paths in the one bus bar;
A third correction component proportional to the current value of the main current flowing downstream from the branch portion with the nearest branch path in the main of the adjacent bus bar;
Based on a correction value obtained by adding together a plurality of fourth correction components proportional to detection values of the magnetic sensors provided in the plurality of branch paths arranged in order including the nearest branch path in the adjacent bus bars. The current measurement apparatus according to claim 5, wherein the measurement value is corrected. The calculation unit is provided on a downstream side from a branch portion between the detection value of the magnetic sensor provided in the other plurality of branch paths in the one bus bar and the one branch path in the trunk of the one bus bar. 8. The measurement value is corrected based on the correction value obtained by further adding a plurality of fifth correction components proportional to the product of the current value of the main current flowing and the square of the current value. The current measuring device described. The calculation unit is provided on a downstream side from a branch portion between the detection value of the magnetic sensor provided in the other plurality of branch paths in the one bus bar and the one branch path in the trunk of the one bus bar. The current measurement according to claim 8, wherein the measurement value is corrected based on the correction value obtained by further adding a plurality of sixth correction components proportional to the product of the current value of the main current that flows. apparatus.