JP2007179901A - Current measuring system of fuel cell, and current measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current measuring system capable of measuring current with high accuracy even at neighboring area of end part in lamination direction of a fuel cell. <P>SOLUTION: Magnetic field generated at neighboring area of a current collection plate 11 arranged at end part in lamination direction of a battery cell lamination body 1 is measured by a group of magnetic sensors 9. A calculation/control device 8 generates magnetic flux density distribution with magnetic flux density component generated by the current flowing through the current collection plate 11 subtracted, by correcting the magnetic flux density distribution based on a measured result of a magnetic field generated at the neighboring area of the current collection plate 11. Further, the calculation/control device 8 calculates the current distribution based on the corrected magnetic flux density distribution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for measuring a current flowing in a fuel cell stack based on a magnetic field generated by the fuel cell stack.

  There is known a fuel cell that converts chemical energy obtained by reacting a fuel gas containing hydrogen with an oxidizing gas containing oxygen into electric energy. The fuel cell is mounted on, for example, a vehicle and is used as a power source for a motor for driving the vehicle.

  The fuel cell is not limited to being mounted on a vehicle, and generates power under various conditions depending on its usage form and usage environment. Therefore, it is desirable to design and manufacture a fuel cell that can maintain stable power generation under various circumstances.

  Therefore, conventionally, various techniques related to evaluation and inspection of fuel cells have been proposed. In particular, Patent Document 1 proposes a method for detecting a current density distribution in a fuel cell from a magnetic field surrounding the fuel cell.

JP-T-2004-500689

  By the method described in Patent Document 1, it is possible to measure the distribution of current flowing in the stacking direction of a fuel cell stack in which a plurality of battery cells are stacked.

  However, the current that flows in the stacking direction of the fuel cell stack is output to the outside of the fuel cell stack via the current collector plate provided at the end in the stacking direction. At that time, the current collected by the current collector plate flows in a direction different from the stacking direction in the current collector plate, for example, in a direction perpendicular to the stacking direction.

  Therefore, when the current flowing in the stacking direction is measured by the method described in Patent Document 1, the magnetic field associated with the current flowing through the current collector plate is superimposed on the magnetic field associated with the current flowing in the stacking direction, and remains in the superimposed state. If the current is measured based on the magnetic field, the current flowing through the current collector plate is superimposed as a noise component of the current flowing in the stacking direction. That is, the current flowing through the current collector plate becomes an error factor when measuring the current flowing in the stacking direction.

  As described above, the conventional current measurement method is affected by the current flowing through the current collector plate, and there is a problem in measurement accuracy in the vicinity of the end of the fuel cell stack in the stacking direction.

  The present invention has been made in such a background, and an object thereof is to enable highly accurate measurement even in the vicinity of the end of the fuel cell stack in the stacking direction.

  In order to achieve the above object, a current measurement system according to a preferred aspect of the present invention measures a current flowing in a fuel cell stack based on a magnetic field generated by a fuel cell stack in which a plurality of battery cells are stacked. A fuel cell current measurement system comprising: a magnetic field measurement unit that measures a magnetic field generated near an end in a stacking direction of the fuel cell stack; and the fuel cell based on a measurement result of the magnetic field generated near the end And a correction unit that corrects the magnetic field state data of the magnetic field generated by the stack, and measures the current in the fuel cell stack based on the corrected magnetic field state data.

  In the above aspect, the magnetic field state data is, for example, a magnetic flux density distribution accompanying a magnetic field generated by the fuel cell stack. That is, according to the said aspect, magnetic field state data, such as magnetic flux density distribution, are correct | amended based on the measurement result of the magnetic field generate | occur | produced in the edge part vicinity. Therefore, for example, even when there is a current that causes noise in the vicinity of the end portion, the magnetic field state data can be generated in consideration of the magnetic field component accompanying the current. For example, it is possible to generate magnetic field state data from which a magnetic field component accompanying a current that causes noise is removed. As a result, when measuring a current to be measured, for example, a current flowing in the stacking direction of the fuel cell stack, highly accurate current measurement is possible even in the vicinity of the end in the stacking direction.

  In a preferred aspect, the magnetic field measurement unit measures a magnetic field generated in the vicinity of a current collector plate provided at an end of the fuel cell stack in the stacking direction, and the correction unit is generated in the vicinity of the current collector plate. By correcting the magnetic field state data based on the measurement result of the magnetic field to be generated, magnetic field state data from which the magnetic field component generated by the current flowing through the current collector plate is removed is generated. According to this aspect, for example, when measuring the current flowing in the stacking direction of the fuel cell stack, measurement errors associated with the current flowing through the current collector plate can be suppressed.

  In a preferred aspect, the correction unit corrects the magnetic flux density distribution, which is the magnetic field state data, based on the magnetic flux density in the vicinity of the current collector obtained as a measurement result of the magnetic field. And generating a magnetic flux density distribution from which the magnetic flux density component is removed.

  In a preferred aspect, the magnetic field measurement unit measures magnetic flux densities at a plurality of points that are plane-symmetric with respect to a plane including the current collector plate, and the correction unit has a plurality of plane-symmetry with respect to each other. The magnetic flux density distribution is corrected based on the magnetic flux density of the points.

  In a preferred aspect, the magnetic field measurement unit includes a plurality of magnetic sensors arranged at a plurality of points that are plane-symmetric to each other, and each magnetic sensor measures a magnetic flux density at each corresponding point. . In a preferred aspect, the magnetic field measurement unit includes a magnetic sensor that moves along the stacking direction of the fuel cell stack, and moves each magnetic sensor stepwise to the positions of the plurality of points that are symmetrical with respect to each other. The magnetic flux density is measured.

  In order to achieve the above object, a current measuring method according to a preferred embodiment of the present invention measures a current flowing in a fuel cell stack based on a magnetic field generated by a fuel cell stack in which a plurality of battery cells are stacked. A method for measuring a current of a fuel cell, wherein a magnetic field generated near an end in the stacking direction of the fuel cell stack is measured, and the fuel cell stack is generated based on a measurement result of the magnetic field generated near the end The magnetic field state data of the magnetic field to be corrected is corrected, and the current in the fuel cell stack is measured based on the corrected magnetic field state data.

  The present invention enables highly accurate current measurement even in the vicinity of the end of the fuel cell stack in the stacking direction.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 is a diagram for explaining a preferred embodiment of the present invention, and FIG. 1 shows an overall configuration diagram of a current measurement system for a fuel cell according to the present invention. The current measurement system of FIG. 1 is a system that measures the current flowing in the battery cell stack 1 of the fuel cell.

  The battery cell laminate 1 measured by this system includes a laminate in which a plurality of battery cells 10 that generate power using, for example, hydrogen and oxygen are laminated. Current collector plates 11 are provided at both ends of the battery cell 10 in the stacking direction, and end plates 13 are further provided outside the stacking direction via insulating plates 12. Thus, the battery cell laminated body 1 has a structure sandwiched by the end plates 13 from both ends in the stacking direction.

  The battery cell stack 1 is also provided with a supply path (not shown) for supplying a fuel gas containing hydrogen and air containing oxygen to each battery cell 10. Then, the current obtained by the power generation by the plurality of battery cells 10 is collected by the current collector plate 11 and supplied to the load via the current collector plate 11.

  Incidentally, when a fuel cell including the battery cell stack 1 is mounted on a vehicle or the like and used as a power source for a vehicle drive motor, the fuel cell supplies current to an inverter or the like that controls the vehicle drive motor. (Electric power) is supplied.

  The fuel supply device 2 is for supplying, for example, a fuel gas (anode gas) containing hydrogen to the battery cell stack 1, and the fuel gas is humidified in the fuel humidifier 4 as necessary before the battery. It is supplied to the cell stack 1. On the other hand, the air supply device 3 is for supplying oxygen-containing air (cathode gas) to the battery cell laminate 1, and the battery cell is used after the air is humidified in the air humidifier 5 as necessary. Supplied to the laminate 1.

  The fuel pressure adjusting device 6 adjusts the pressure of the exhaust gas discharged from the anode side of the battery cell stack 1, and the air pressure adjusting device 7 is discharged from the cathode side of the battery cell stack 1. It adjusts the pressure of exhaust gas.

  Each of the fuel supply device 2, the air supply device 3, the fuel humidifier 4, the air humidifier 5, the fuel pressure adjustment device 6, and the air pressure adjustment device 7 included in this system is controlled by an arithmetic / control device 8. The arithmetic / control device 8 controls the fuel supply device 2 and the like, thereby controlling the flow rate of the fuel gas supplied to the battery cell stack 1, the amount of water vapor contained in the fuel gas, and the air supplied to the battery cell stack 1. By appropriately adjusting the flow rate of water, the amount of water vapor contained in the air, the pressure on the anode side or the pressure on the cathode side in the battery cell stack 1, various power generation states of the battery cell stack 1 can be realized. it can.

  And in this system, the electric current which flows through the inside of the battery cell laminated body 1 which generate | occur | produces in various electric power generation states is measured. The current is measured using a magnetic field generated around the battery cell stack 1 by the current.

  The magnetic sensor group 9 detects a magnetic field generated around the battery cell stack 1, and a plurality of magnetic sensor groups 9 are arranged side by side along the stacking direction of the battery cell stack 1. Although simplified in FIG. 1, each magnetic sensor group 9 has a structure surrounding the battery cell stack 1.

  FIG. 2 is a view for explaining the structure of each magnetic sensor group 9, and is a cross-sectional view taken along a plane perpendicular to the stacking direction of the battery cell stack 1 of FIG. Each magnetic sensor group 9 includes a sensor attachment frame 15 surrounding the battery cell stack 1 and a plurality of three-axis magnetic sensors 14 attached to the sensor attachment frame 15. Each triaxial magnetic sensor 14 measures the magnetic field at the position where it is arranged, and detects the magnetic flux density in the triaxial direction at that position.

  As shown in FIG. 2, a plurality of three-axis magnetic sensors 14 included in each magnetic sensor group 9 are arranged so as to surround the battery cell stack 1, and further, as shown in FIG. They are arranged side by side along the stacking direction of the cell stack 1. As a result, a plurality of triaxial magnetic sensors 14 are arranged so as to surround the entire four side surfaces of the battery cell stack 1, and a magnetic field generated around the battery cell stack 1 is detected by the plurality of triaxial magnetic sensors 14. The

  FIG. 3 is a diagram for explaining a magnetic field generated around the battery cell stack 1. As described above, the current obtained by the power generation of each battery cell of the battery cell stack 1 is collected by the current collector plate 11 and supplied to the load via the current collector plate 11. For this reason, when the current flow in the battery cell stack 1 is grasped globally, it can be roughly divided into a current A flowing from each battery cell toward the current collector plate 11 and a current B flowing in the current collector plate 11. That is, there is a current A that flows along the stacking direction of the battery cell stack 1 and a current B that flows in a direction substantially perpendicular to the current A. The magnetic field lines A are formed by the current A, and the magnetic field lines B are formed by the current B.

  When the power generation state of the battery cell stack 1 is confirmed, the current distribution of the current A becomes one of important indexes. For example, the distribution of the current A in the stacking direction is a standard for confirming the power generation state of each of the plurality of battery cells. The current distribution of the current A flowing through the battery cell stack 1 can be detected from the magnetic field surrounding the battery cell stack 1 by using the method of Patent Document 1 described above.

  However, as shown in FIG. 3, there is also a current B flowing in the current collector plate 11 in the battery cell stack 1. Therefore, when a magnetic field surrounding the battery cell stack 1 is detected for the purpose of confirming the current distribution of the current A, the detected magnetic field includes a magnetic field component accompanying the current B. That is, the magnetic field component accompanying the current B becomes a noise component when measuring the current distribution of the current A.

  In the present embodiment, the magnetic field component accompanying the current B is removed by the method described in detail below. As a result, according to the present embodiment, the current distribution of the current A can be measured with extremely high accuracy.

  FIG. 4 is a diagram for explaining the current flowing through the current collector plate 11. When the current flowing in the current collector plate 11 is roughly grasped, the current B shown in FIG. 3 is obtained. However, in more detail, the current flowing in the current collector plate 11 is a terminal 11 as shown in FIG. It is accompanied by a complicated flow so as to concentrate in one place toward ′. Therefore, the lines of magnetic force generated by the current flowing in the current collector plate 11 are complex lines of magnetic force including all components in the XYZ axial directions (see FIG. 3).

  In the current measurement system of the present embodiment, the complex magnetic field lines generated by the current flowing in the current collector plate 11 based on the detection result of the magnetic sensor group (reference numeral 9 in FIG. 1) arranged in the vicinity of the current collector plate 11. Are removed. Therefore, the magnetic sensor group disposed in the vicinity of the current collector plate 11 will be described.

  FIG. 5 is a view for explaining an arrangement state of the magnetic sensor group 9 arranged in the vicinity of the current collector plate 11 and is a partial view showing an end portion in the stacking direction of the battery cell stack 1 of FIG. . That is, FIG. 5 is a partial view of the vicinity of the current collector plate 11 provided at the end of the battery cell 10 in the stacking direction, and the insulating plate 12 and the end plate 13 disposed outside the current collector plate 11 in the stacking direction are also illustrated. It is shown in the figure.

  In the vicinity of the current collector plate 11, the magnetic sensor group 9 is disposed at a position separated by a distance a on the positive direction side in the Z-axis direction (stacking direction) with the position of the current collector plate 11 as the origin. The magnetic sensor group 9 is also arranged at a position separated by a distance a on the negative direction side in the Z-axis direction. Further, the magnetic sensor group 9 is also arranged at a position away from the origin by a distance b on the positive side in the Z-axis direction and a distance b on the negative side, and the distance from the origin to the positive side in the Z-axis direction. The magnetic sensor group 9 is also arranged at a position separated by c and a position separated by a distance c on the negative direction side. Thus, in the current measurement system of the present embodiment, a set of magnetic sensor groups 9 having the same distance from the origin (current collector plate 11) on the Z axis is formed.

  Incidentally, the distance b does not have to be twice the distance a, and the distance c does not have to be three times the distance a. That is, it is not necessary that all the magnetic sensor groups 9 are arranged at equal intervals along the Z-axis direction (stacking direction). However, all the magnetic sensor groups 9 may be arranged at equal intervals along the Z-axis direction.

  Although simplified in FIG. 5, each magnetic sensor group 9 includes a plurality of triaxial magnetic sensors, and the plurality of triaxial magnetic sensors included in each magnetic sensor group 9 includes a battery cell stack. It surrounds the body 1 (see FIG. 2). The plurality of triaxial magnetic sensors are arranged at positions that are symmetrical with respect to each other with the plane including the current collector plate 11 as a plane of symmetry. That is, for example, a plurality of three-axis magnetic sensors of the magnetic sensor group 9 provided at a position a distance a on the positive direction side from the origin, and a magnetic sensor group provided at a position a distance a on the negative direction side from the origin. A plurality of nine triaxial magnetic sensors are arranged at positions that are plane-symmetric with respect to the plane including the current collector plate 11 as a plane of symmetry.

  In the current measurement system of the present embodiment, a complicated magnetic field component generated by the current flowing in the current collector plate 11 based on the magnetic detection results of the two triaxial magnetic sensors arranged at positions symmetrical with respect to each other. Correction is performed to remove.

  6 and 7 are diagrams for explaining the principle of correction by the current measurement system of the present embodiment. Each of FIGS. 6 and 7 shows a distribution state of magnetic flux density in the vicinity of the current collector plate. The horizontal axis of each figure shows a Z-axis (FIG. 3) that is the stacking direction of the battery cell stack. Corresponding to the Z axis). The origin is the position of the current collector plate. 6 represents the magnetic flux density in the X direction (corresponding to the X axis direction in FIG. 3), and the vertical axis in FIG. 7 represents the Z direction (corresponding to the Z axis direction in FIG. 3). The magnetic flux density is shown.

（１−１）式から（１−３）式には図６に示す各磁束密度成分の関係が示されている。また（１−４）式のＫ（ｚ）は、集電板からの距離ｚに応じた係数であり、電流Ａによって発生する磁束密度の理論波形から求めることができる。 In FIG. 6, Bx (z) is a magnetic flux density component in the X direction generated by the current A and the current B (see FIG. 3), and Bx ′ (z) is a magnetic flux density component in the X direction generated by the current A. , Tx (z) are magnetic flux density components in the X direction generated by the current B. Further, FIG. 6 clearly shows each magnetic flux density component at a position z on the Z axis and each magnetic flux density component at a position −z on the Z axis. The relationship between the magnetic flux density components shown in FIG.

Expressions (1-1) to (1-3) show the relationship between the magnetic flux density components shown in FIG. Further, K (z) in the expression (1-4) is a coefficient corresponding to the distance z from the current collector plate and can be obtained from the theoretical waveform of the magnetic flux density generated by the current A.

  FIG. 8 is a diagram showing the magnetic flux density generated only by the current A. That is, FIG. 8 shows a graph of magnetic flux density generated around the battery cell stack only by the current A flowing in the stacking direction of the battery cell stack. In FIG. 8, the horizontal axis is the stacking direction (Z-axis), and the vertical axis is the magnetic flux density. The waveform shown in FIG. 8 is a theoretical waveform when the current A flows in the stacking direction when the current A is given a certain value.

さらに、電流分布を表すベクトルＪと磁束密度を表すベクトルＢとの対応関係を、システム行列Ｃによって表現すると次式のようになる。

システム行列Ｃは、ビオ・サバールの法則などから決定することができる。そこで、電池セル積層体の積層方向に流れる電流Ａに対応する電流分布ベクトルを与えることにより、数３式から、磁束密度ベクトルを求めることができる。つまり、数３式を利用することにより、積層方向に流れる電流Ａによって発生する磁束密度の理論値を求めることができ、図８に示す理論波形を得ることができる。 The relationship between the current and the magnetic field (magnetic flux density) generated along with it is known as Bio-Savart's law. That is, the magnetic flux density dB generated by the minute portion dL of the conducting wire through which the steady current I flows, at the point where the position vector thereof is r is given by the following equation.

Further, when the correspondence relationship between the vector J representing the current distribution and the vector B representing the magnetic flux density is expressed by the system matrix C, the following expression is obtained.

The system matrix C can be determined from Bio Savart's law. Therefore, by providing a current distribution vector corresponding to the current A flowing in the stacking direction of the battery cell stack, the magnetic flux density vector can be obtained from Equation (3). That is, by using Equation 3, the theoretical value of the magnetic flux density generated by the current A flowing in the stacking direction can be obtained, and the theoretical waveform shown in FIG. 8 can be obtained.

  The coefficient K (z) in the equation (1-4) is a coefficient indicating the correspondence between Bx ′ (− z) and Bx ′ (z) when the position of the current collector plate is the origin. Therefore, in the theoretical waveform of FIG. 8, from the position corresponding to the origin (current collector plate) of the Z axis in FIGS. 6 and 7, the magnetic flux density on the positive direction side of the Z axis and the negative of the Z axis are determined from that position. By obtaining the correspondence with the direction-side magnetic flux density, the coefficient K (z) can be obtained from the correspondence.

  Then, the expression (1-5) is derived from the expression (1-1) based on the expression (1-4). The expression (1-5) is an expression for deriving a magnetic flux density component Bx ′ (z) in the X direction in which the current A is generated at the position z, and Bx ′ (z) is Bx (z), Bx (−z). , K (z). Here, as described with reference to FIG. 8, K (z) is a coefficient obtained from the theoretical waveform, and is obtained in advance, for example, before the current is measured by the current measurement system.

  Bx (z) and Bx (−z) are magnetic flux density components generated by the current A and the current B (see FIG. 3), and these values can be obtained from the detection result of the magnetic field by the three-axis magnetic sensor. . Bx (z) is the magnetic flux density at the position z when the position of the current collector plate is the origin, and Bx (−z) is the magnetic flux at the position −z when the position of the current collector is the origin. Density. That is, Bx (z) and Bx (−z) are magnetic flux densities at two positions that are plane-symmetric with respect to the plane including the current collector plate.

  As described with reference to FIG. 5, in the current measurement system of the present embodiment, two triaxial magnetic sensors are arranged in positions near the current collector plate in plane symmetry with each other. Therefore, from the detection results of these two triaxial magnetic sensors, the magnetic flux density component Bx ′ (z) in the X direction in which the current A is generated can be obtained using Equation (1-5). That is, the magnetic flux density component accompanying the current B can be removed.

  The distribution state of the magnetic flux density in the X direction is shown in FIG. 6, but the distribution state of the magnetic flux density in the Y direction is the same as that in the X direction. That is, the vertical axis in FIG. 6 is the magnetic flux density in the Y direction, Bx (z) is By (z), Bx ′ (z) is By ′ (z), and Tx (z) is Ty (z). Can be replaced. Here, By (z) is a magnetic flux density component in the Y direction generated by the current A and the current B, By ′ (z) is a magnetic flux density component in the Y direction generated by the current A, and Ty (z) is This is a magnetic flux density component in the Y direction generated by the current B.

（２−４）式の係数Ｋ（ｚ）は、（１−４）式の係数Ｋ（ｚ）と同じである。このため、Ｘ方向の磁束密度を求める場合と同様に、Ｙ方向の磁束密度を求める場合においても、互いに面対称となる位置に配置された二つの三軸磁気センサの検出結果から、（２−５）式を利用して、電流Ａが発生するＹ方向の磁束密度成分Ｂｙ´（ｚ）を求めることができる。つまり、電流Ｂに伴う磁束密度成分を除去することができる。 Accordingly, the following relational expressions regarding the magnetic flux density in the Y direction are established corresponding to the relational expressions (1-1) to (1-5) regarding the magnetic flux density in the X direction.

The coefficient K (z) in the equation (2-4) is the same as the coefficient K (z) in the equation (1-4). For this reason, as in the case of obtaining the magnetic flux density in the X direction, in the case of obtaining the magnetic flux density in the Y direction, from the detection results of the two triaxial magnetic sensors arranged at positions symmetrical to each other, (2- 5) The magnetic flux density component By ′ (z) in the Y direction in which the current A is generated can be obtained using the equation (5). That is, the magnetic flux density component accompanying the current B can be removed.

（３−１）式から（３−３）式には図７に示す各磁束密度成分の関係が示されている。また（３−４）式の係数Ｋ（ｚ）は集電板からの距離ｚに応じた係数であり、（１−４）式の係数Ｋ（ｚ）と同じである。 FIG. 7 shows a distribution state of magnetic flux density in the Z direction. In FIG. 7, Bz (z) is a magnetic flux density component in the Z direction generated by the current A and the current B (see FIG. 3), and Bz ′ (z) is a magnetic flux density component in the Z direction generated by the current A. , Tz (z) are magnetic flux density components in the Z direction generated by the current B. Further, FIG. 7 clearly shows each magnetic flux density component at a position z on the Z axis and each magnetic flux density component at a position −z on the Z axis. The relationship between the magnetic flux density components shown in FIG. 7 is expressed by the following equation.

Expressions (3-1) to (3-3) show the relationship between the magnetic flux density components shown in FIG. Further, the coefficient K (z) in the expression (3-4) is a coefficient corresponding to the distance z from the current collector, and is the same as the coefficient K (z) in the expression (1-4).

  Then, the expression (3-5) is derived from the expression (3-1) based on the expression (3-4). The expression (3-5) is an expression for deriving a magnetic flux density component Bz ′ (z) in the Z direction in which the current A is generated at the position z, and Bz ′ (z) is Bz (z), Bz (−z). , K (z). Here, K (z) is a coefficient obtained from the theoretical waveform, and is obtained in advance, for example, before the current is measured by the current measurement system.

  Bz (z) and Bz (−z) are magnetic flux density components generated by the current A and the current B (see FIG. 3), and these values are plane-symmetric with respect to the plane including the current collector plate as a plane of symmetry. It is obtained from the detection results of two triaxial magnetic sensors arranged at two positions. Therefore, the magnetic flux density component Bz ′ (z) in the Z direction in which the current A is generated can be obtained from the detection results of these two triaxial magnetic sensors using the expression (3-5). That is, the magnetic flux density component accompanying the current B can be removed.

  In this way, from the detection results of the two triaxial magnetic sensors arranged at two points that are plane-symmetric with each other, the formulas (1-5), (2-5), and (3-5) are used. Thus, the respective magnetic flux density components in the XYZ directions in which the current A is generated can be obtained.

  In this way, the calculation / control device 8 in FIG. 1 calculates the battery cell stack from the detection results of the magnetic flux density obtained from the plurality of magnetic sensor groups 9, that is, the detection results of the plurality of triaxial magnetic sensors surrounding the battery cell stack 1. The magnetic flux density at a plurality of points surrounding 1 is obtained. At that time, in the vicinity of the current collector plate 11, the magnetic flux density component associated with the current B is removed by using the formulas (1-5), (2-5), and (3-5). The respective magnetic flux density components in the XYZ directions where A is generated are obtained.

  At a point away from the current collector plate 11, the magnetic flux density component associated with the current B is removed using the equations (1-5), (2-5), and (3-5), You may obtain | require each magnetic flux density component of the XYZ direction which the electric current A generate | occur | produces. Further, at a point away from the current collector plate 11, for example, a point more than a predetermined distance, it is considered that the magnetic flux density component accompanying the current B is zero, and the magnetic flux density obtained from the three-axis magnetic sensor is directly used. May be.

数６を利用することにより、磁束密度ベクトルＢから電流分布ベクトルＪを求めることができる。なお、磁束密度ベクトルから電流分布ベクトルを求める手法は、従来から公知の手法、例えば特許文献１に記載の手法を利用してもよい。 As described above, the calculation / control device 8 in FIG. 1 determines the magnetic flux density vector (each magnetic flux density component in the XYZ directions) around the battery cell stack 1 from the detection result of the magnetic flux density by the plurality of magnetic sensor groups 9. ) And a current distribution vector from the magnetic flux density vector. For example, by using the inverse matrix of the system matrix C shown in Equation 3, the following relationship is derived.

By using Equation 6, the current distribution vector J can be obtained from the magnetic flux density vector B. As a method for obtaining the current distribution vector from the magnetic flux density vector, a conventionally known method, for example, a method described in Patent Document 1 may be used.

  FIG. 9 is a diagram for explaining another preferred embodiment of the present invention. FIG. 9 shows a modification of the current measurement system according to the present invention.

  The current measurement system of FIG. 9 is a system that measures the current flowing in the battery cell stack 1 as in the current measurement system of FIG. The battery cell laminate 1 includes a laminate in which a plurality of battery cells 10 are laminated, current collector plates 11 are provided at both ends of the battery cells 10 in the stacking direction, and an insulating plate is provided outside the stacking direction. An end plate 13 is provided via 12.

  The fuel supply device 2 is for supplying, for example, a fuel gas (anode gas) containing hydrogen to the battery cell stack 1, and the fuel gas is humidified in the fuel humidifier 4 as necessary before the battery. It is supplied to the cell stack 1. On the other hand, the air supply device 3 is for supplying oxygen-containing air (cathode gas) to the battery cell laminate 1, and the battery cell is used after the air is humidified in the air humidifier 5 as necessary. Supplied to the laminate 1.

  The fuel pressure adjusting device 6 adjusts the pressure of the exhaust gas discharged from the anode side of the battery cell stack 1, and the air pressure adjusting device 7 is discharged from the cathode side of the battery cell stack 1. It adjusts the pressure of exhaust gas.

  Also in the current measurement system of FIG. 9, each of the fuel supply device 2, the air supply device 3, the fuel humidifier 4, the air humidifier 5, the fuel pressure adjustment device 6, and the air pressure adjustment device 7 is operated by the calculation / control device 8. Be controlled.

  The major difference between the current measurement system of FIG. 9 and the current measurement system of FIG. 1 is that in the system of FIG. 9, one magnetic sensor group 9 is moved along the stacking direction of the battery cell stack 1 by the sensor driving device 16. It is to be done. The structure of one magnetic sensor group 9 in FIG. 9 is the same as one of the plurality of magnetic sensor groups 9 in FIG. That is, as described with reference to FIG. 2, the magnetic sensor group 9 in FIG. 9 includes a sensor mounting frame (reference numeral 15 in FIG. 2) surrounding the battery cell stack 1 and a plurality of sensor mounting frames mounted on the sensor mounting frame. 3 axis magnetic sensor (reference numeral 14 in FIG. 2).

  In the system of FIG. 9, one magnetic sensor group 9 moves stepwise from one end to the other end in the stacking direction along the stacking direction of the battery cell stack 1, and the battery cell stack 1 at each moving position. The magnetic flux density around is measured. The position where the magnetic sensor group 9 measures the magnetic flux density while moving is the position where the plurality of magnetic sensor groups 9 in FIG. 1 measure the magnetic flux density. That is, in the current measurement system of FIG. 9, the magnetic field generated around the battery cell stack 1 is detected by moving one magnetic sensor group 9.

  Therefore, also in the current measurement system of FIG. 9, the magnetic flux density is detected in the vicinity of the current collector plate 11 at positions that are plane-symmetric with respect to the plane including the current collector plate 11. Then, the arithmetic / control device 8 uses the equations (1-5), (2-5), and (3-5) to remove the magnetic flux density component associated with the current B, thereby generating the current A. The respective magnetic flux density components in the XYZ directions are obtained. Furthermore, by using Equation 6, a current distribution vector can be obtained from the magnetic flux density vector.

  The preferred embodiment of the present invention has been described above. In the current measurement system (FIGS. 1 and 9) of the present embodiment, the respective magnetic flux density components in the XYZ directions are obtained at the stage of obtaining the magnetic flux density vector. In the stage, the magnetic flux density component accompanying the current B flowing through the current collector plate is removed. For this reason, the current distribution of the current A can be measured with high accuracy even in the vicinity of the current collector plate. In the current measurement system of the present embodiment, the magnetic flux densities at two points that are plane-symmetric with respect to each other are used to relatively compare the equations (1-5), (2-5), and (3-5). Correction can be performed with a simple calculation. Therefore, the calculation processing load for correction is small.

  The above-described embodiments are merely examples in all respects, and do not limit the scope of the present invention.

1 is an overall configuration diagram of a current measurement system for a fuel cell according to the present invention. It is a figure for demonstrating the structure of each magnetic sensor group. It is a figure for demonstrating the magnetic field which generate | occur | produces around a battery cell laminated body. It is a figure for demonstrating the electric current which flows through the inside of a current collecting plate. It is a figure which shows the arrangement | positioning state of the magnetic sensor group arrange | positioned in the vicinity of a current collecting plate. It is a figure which shows the distribution state of the magnetic flux density in the vicinity of a current collecting plate. It is a figure which shows the distribution state of the magnetic flux density in the vicinity of a current collecting plate. It is a figure which shows the magnetic flux density which generate | occur | produces only with the electric current A. FIG. It is a figure for demonstrating another suitable embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Battery cell laminated body, 8 Calculation / control apparatus, 9 Magnetic sensor group, 10 Battery cell, 11 Current collecting plate.

Claims (7)

A fuel cell current measurement system for measuring a current flowing in a fuel cell stack based on a magnetic field generated by a fuel cell stack in which a plurality of battery cells are stacked,
A magnetic field measurement unit for measuring a magnetic field generated near an end of the fuel cell stack in the stacking direction;
A correction unit that corrects the magnetic field state data of the magnetic field generated by the fuel cell stack based on the measurement result of the magnetic field generated near the end; and
Have
Measuring a current in the fuel cell stack based on the corrected magnetic field state data;
A current measurement system for a fuel cell. The current measurement system according to claim 1,
The magnetic field measurement unit measures a magnetic field generated in the vicinity of a current collector plate provided at an end in the stacking direction of the fuel cell stack,
The correction unit corrects the magnetic field state data based on a measurement result of a magnetic field generated in the vicinity of the current collector plate, thereby obtaining magnetic field state data from which a magnetic field component generated by a current flowing through the current collector plate is removed. Generate,
A current measurement system for a fuel cell. The current measurement system according to claim 2,
The correction unit corrects the magnetic flux density distribution, which is the magnetic field state data, based on the magnetic flux density in the vicinity of the current collector plate obtained as a result of the magnetic field measurement, so that the magnetic flux density associated with the current flowing through the current collector plate Generate a magnetic flux density distribution with components removed,
A current measurement system for a fuel cell. The current measurement system according to claim 3,
The magnetic field measurement unit measures the magnetic flux density at a plurality of points that are plane-symmetric with respect to the plane including the current collector plate as a symmetry plane,
The correction unit corrects the magnetic flux density distribution based on magnetic flux densities at a plurality of points that are plane-symmetric with respect to each other.
A current measurement system for a fuel cell. The current measurement system according to claim 4,
The magnetic field measurement unit includes a plurality of magnetic sensors arranged at a plurality of points that are plane-symmetric with respect to each other, and measures the magnetic flux density at each point corresponding to each magnetic sensor,
A current measurement system for a fuel cell. The current measurement system according to claim 4,
The magnetic field measurement unit includes a magnetic sensor that moves along the stacking direction of the fuel cell stack, and moves the magnetic sensor stepwise to the positions of the plurality of points that are symmetrical with respect to each other to obtain the magnetic flux density at each point. measure,
A current measurement system for a fuel cell. A fuel cell current measurement method for measuring a current flowing in a fuel cell stack based on a magnetic field generated by a fuel cell stack in which a plurality of battery cells are stacked,
Measure the magnetic field generated near the end of the fuel cell stack in the stacking direction,
Correct the magnetic field state data of the magnetic field generated by the fuel cell stack based on the measurement result of the magnetic field generated near the end,
Measuring a current in the fuel cell stack based on the corrected magnetic field state data;
A method for measuring a current of a fuel cell.

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