Impedance measuring device and impedance measuring method

Abstract

To measure the impedance of an impedance element to be measured in a state in which a non-measured subject is connected in parallel to the subject to be measured via a connection line.SOLUTION: The present invention comprises: a measurement-current output unit 2 that, in a state in which a power-supply device PD is connected in parallel via a connection line Lc to a measurement target DUT configured by connecting electrochemical cells C in series, supplies an AC current Im for measurement to the electrochemical cells; a voltage measurement unit 3 that measures a voltage value V at both ends of the electrochemical cells; a current sensor 4-1 that measures a supply current value of the AC current for measurement; and a processing unit 5 that calculates impedance of the electrochemical cells on the basis of the voltage value V and the supply current value. The measurement-current output unit 2 supplies the AC current for measurement to measurement-current supply points Po1 and Po2, which are specified so that one or more electrochemical cells are included in a current path IR2, and supplies the AC current for measurement to a part of the plurality of electrochemical cells other than the one or more electrochemical cells, the part serving as electrochemical cells to be measured.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an impedance measuring device and an impedance measuring method capable of measuring the impedance of some of a plurality of measurement target impedance elements in a state where a non-measurement target is connected in parallel via a connection line to a measurement target configured by connecting a plurality of impedance elements in series.

Background Art

[0002] As an impedance measuring device capable of measuring the impedance of a measurement target in a state where a non-measurement target is connected in parallel via a connection line to the measurement target, an impedance measuring device disclosed in the following patent document is known. This impedance measuring device is configured to be able to measure the internal impedance of the measurement target in a state where the non-measurement target is connected in parallel via a connection line to the measurement target. Specifically, this impedance measuring device includes an alternating current supply unit, an alternating voltage detection unit, an alternating current detection unit, an A / D conversion unit, and an arithmetic control unit. In this case, the alternating current detection unit includes a clamp-type current sensor.

[0003] When measuring the internal impedance of a measurement target that is connected in parallel with a non-measurement target via a connection line using this impedance measurement device, first, the connection line is inserted through the opening of the clamp-type current sensor in the alternating current detection unit. In this state, the alternating current supply unit supplies a measurement alternating current to both ends of the measurement target. As a result, a part of the measurement alternating current flows through the measurement target, and the remaining part of the measurement alternating current flows through the non-measurement target. In this case, the current sensor of the alternating current detection unit detects the alternating current flowing through the power line passing through the opening and outputs a negative feedback current corresponding to the alternating current value of the alternating current. At this time, an alternating voltage is generated across the detection resistor due to the flow of the feedback current. Next, the A / D conversion unit performs A / D conversion on the alternating current data indicating the alternating current value and outputs it to the arithmetic control unit. Also, the alternating voltage detection unit detects the voltage value across both ends of the measurement target and outputs the alternating voltage data indicating the voltage value across both ends to the arithmetic control unit. Then, the arithmetic control unit calculates the internal impedance of the measurement target based on the alternating current value indicated by the input alternating current data and the voltage value across both ends indicated by the input alternating voltage data.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the above impedance measurement device has the following problems. Specifically, for example, an example of measuring the internal impedance of a measurement target DUT when a power supply device PD as a non-measurement target is connected to an electrolysis device (hereinafter also referred to as an "electrolysis device") as the measurement target DUT via a connection line Lc will be described. In this case, the measurement target DUT is configured by stacking a plurality of electrochemical cells C1 to C10 (hereinafter also referred to as "electrochemical cell C" when not distinguished) as impedance elements. Also, the measurement system at that time is conceptually shown in FIG. 4. As shown in the figure, in this measurement system, the power supply device PD is connected in parallel to the measurement target DUT via a connection line Lc connected to the terminals T1 and T11 of the measurement target DUT. Also, an alternating current supply unit U1 is connected to the terminals T1 and T11 of the measurement target DUT via a measurement current supply line Li, and an alternating voltage detection unit U2 is connected to the terminals T1 and T11. Also, a current sensor S outputs alternating current data indicating the current value of the measurement alternating current Im flowing through the measurement target DUT to an arithmetic control unit U3.

[0006] Therefore, when measuring the internal impedance of the measurement target DUT using this impedance measurement device 1X, first, the alternating current supply unit U1 outputs a measurement alternating current Im with a current value I10 and supplies it to the measurement target DUT. In this state, the measurement alternating current Im is a measurement alternating current Im (a part of the current value I10) with a current value I11 flowing through a current path composed of one terminal of the alternating current supply unit U1, the measurement current supply line Li, the terminal T1, the measurement target DUT, the terminal T11, the measurement current supply line Li, and the other terminal of the alternating current supply unit U1, and a measurement alternating current Im (the remaining part of the current value I10) with a current value I12 flowing through a current path composed of one terminal of the alternating current supply unit U1, the measurement current supply line Li, the terminal T1, the connection line Lc, the power supply device PD, the connection line Lc, the terminal T11, the measurement current supply line Li, and the other terminal of the alternating current supply unit U1.

[0007] At this time, the AC voltage detection unit U2 detects the voltage value across the terminals T1 and T11 of the DUT under measurement and outputs AC voltage data to the arithmetic control unit U3. Also, the current sensor S outputs AC current data indicating the current value I11 of the measurement AC current Im flowing through the DUT under measurement to the arithmetic control unit U3. Next, the arithmetic control unit U3 calculates the internal impedance of the DUT under measurement based on the voltage value across the DUT under measurement indicated by the input AC voltage data and the current value I11 of the measurement AC current Im flowing through the DUT under measurement indicated by the input AC current data.

[0008] In this case, in this example, since the impedance of the power supply device PD is extremely small, the current value I12 of the measurement AC current Im flowing through the power supply device PD by shunting becomes extremely large, while the current value I11 of the measurement AC current Im flowing through the DUT under measurement by shunting becomes extremely small. Therefore, since the current value I11 of the measurement AC current detected by the current sensor S is extremely small, there is a problem that it becomes extremely difficult for the arithmetic control unit U3 to measure the internal impedance of the DUT under measurement.

[0009] Also, it may be desired to measure the impedance of some of the plurality of electrochemical cells C (measurement target impedance elements) within the DUT to be measured. In this case, an AC voltage detection unit U2 is connected to both ends of the electrochemical cell C for which measurement is desired, and the voltage value across both ends of the electrochemical cell C is measured. Next, the arithmetic control unit U3 calculates the impedance of the electrochemical cell C based on the voltage value across both ends of the electrochemical cell C indicated by the input AC voltage data and the current value I11 of the measurement AC current Im flowing through the DUT to be measured (the electrochemical cell C for which measurement is desired) indicated by the input AC current data. However, also in this case, since the impedance of the power supply device PD is extremely small, the current value I12 of the measurement AC current Im that shunts and flows through the power supply device PD becomes extremely large, while the current value I11 of the measurement AC current Im that shunts and flows through the DUT to be measured (the electrochemical cell C for which measurement is desired) becomes extremely small. Therefore, since the current value I11 of the measurement AC current Im detected by the current sensor S is extremely small, there is a problem that it becomes extremely difficult for the arithmetic control unit U3 to measure the impedance of the electrochemical cell C for which measurement is desired.

[0010] The present invention has been made in view of such problems, and a main object thereof is to provide an impedance measurement device and an impedance measurement method capable of reliably measuring the impedance of a measurement target impedance element in a state where a non-measurement target is connected in parallel via a connection line to a measurement target configured by connecting a plurality of impedance elements in series.

Means for Solving the Problems

[0011] To achieve the above object, an impedance measuring apparatus according to the present invention includes a measurement current supply unit that supplies a measurement current to a plurality of impedance elements, a voltage measurement unit that measures both-end voltage values at both ends of the impedance elements when the measurement current is being supplied, a first current sensor that measures a supply current value of the measurement current supplied to the impedance elements, and a processing unit that calculates an impedance of the impedance elements based on the measured both-end voltage values and the supply current value. The measurement current supply unit supplies the measurement current to a pair of measurement current supply points defined such that one or more of the plurality of impedance elements are included in a current path through which the measurement current flows in the connection line, so that a part of the plurality of impedance elements other than the one or more impedance elements is used as a measurement target impedance element, and the measurement current is supplied to the measurement target impedance element. The voltage measurement unit measures the both-end voltage value of the measurement target impedance element, and the processing unit calculates the impedance of the measurement target impedance element based on the measured both-end voltage value and the supply current value.

[0012] Also, in order to achieve the above object, an impedance measurement method according to the present invention supplies a measurement current to a plurality of impedance elements while measuring both-end voltage values at both ends of the impedance elements when the measurement current is being supplied, and measures a supply current value of the measurement current supplied to the impedance elements by a first current sensor, in a state where a non-measurement object is connected in parallel via a connection line to a measurement object configured by connecting the plurality of impedance elements in series. The impedance of the impedance elements is measured based on the measured both-end voltage values and the supply current value. The measurement current is supplied to a pair of measurement current supply points defined such that one or more of the plurality of impedance elements are included in a current path through which the measurement current flows in the connection line, so that a part of the plurality of impedance elements other than the one or more impedance elements is used as a measurement target impedance element, the measurement current is supplied to the measurement target impedance element, the both-end voltage value of the measurement target impedance element is measured, and the impedance of the measurement target impedance element is measured based on the measured both-end voltage value and the supply current value.

[0013] In this impedance measurement device and impedance measurement method, the measurement AC current is supplied to a pair of measurement current supply points defined such that one or more impedance elements are included in a current path through which the measurement AC current flows in the connection line, so that a part of the plurality of impedance elements other than the one or more impedance elements is used as a measurement target impedance element, the measurement AC current is supplied to the measurement target impedance element, the both-end voltage value of the measurement target impedance element is measured, and the impedance of the measurement target impedance element is measured based on the measured both-end voltage value and the supply current value.

[0014] Therefore, according to this impedance measuring apparatus and impedance measuring method, even when a non-measurement object with a low impedance is connected in parallel to a measurement object configured by connecting a plurality of impedance elements in series, some of the plurality of impedance elements can be used as measurement target impedance elements, and an AC current for measurement with a sufficiently large current value can be supplied to the measurement target impedance elements. As a result, it is possible to measure the voltage value across the measurement target impedance elements when the AC current for measurement is supplied to the measurement target impedance elements and the supply current value of the AC current for measurement flowing through the measurement target impedance elements, so that the impedance of the measurement target impedance elements can be reliably measured.

[0015] Further, in the impedance measuring apparatus according to the present invention, the measurement current supply unit supplies the measurement current to the pair of measurement current supply points defined at positions electrically the same as the pair of voltage measurement points for measuring the voltage across the measurement target impedance elements.

[0016] Further, in the impedance measuring method according to the present invention, the pair of measurement current supply points are defined at positions electrically the same as the pair of voltage measurement points for measuring the voltage across the measurement target impedance elements, and the measurement current is supplied.

[0017] In this impedance measuring apparatus and impedance measuring method, by defining a pair of measurement current supply points at electrically the same positions as a pair of voltage measurement points for measuring the voltage across both ends of the impedance element to be measured and supplying a measurement alternating current, it is possible to include the largest number of impedance elements in the current path that does not include the impedance element to be measured. Therefore, even if the non-measurement object has a low impedance, the overall impedance of the current path can be made sufficiently large. For this reason, according to this impedance measuring apparatus and impedance measuring method, the current value of the measurement alternating current flowing through the connection line by shunt can be minimized, and as a result, the current value of the measurement alternating current flowing through the impedance element to be measured by shunt can be maximized. Consequently, the voltage value across both ends at both ends of the impedance element to be measured can be made sufficiently large. Thereby, according to this impedance measuring apparatus and impedance measuring method, the ratio (S / N) of the signal level (S) to the noise level (N) of the voltage across both ends to be measured can be sufficiently increased, so that the impedance of the impedance element to be measured can be measured with sufficiently high accuracy.

[0018] Further, the impedance measuring apparatus according to the present invention includes a second current sensor that measures the current value of the measurement current flowing through the connection line, and the processing unit subtracts the current value measured by the second current sensor from the supply current value measured by the first current sensor to calculate a new supply current value, and calculates the impedance of the impedance element to be measured based on the measured voltage value across both ends and the calculated new supply current value.

[0019] Further, in the impedance measuring method according to the present invention, the current value of the measurement current flowing through the connection line is measured by a second current sensor, the current value measured by the second current sensor is subtracted from the supply current value measured by the first current sensor to calculate a new supply current value, and the impedance of the impedance element to be measured is measured based on the measured voltage value across both ends and the calculated new supply current value.

[0020] In this impedance measuring device and impedance measuring method, the current value of the measurement alternating current flowing through the connection line is measured by a second current sensor, and the current value measured by the second current sensor is subtracted from the current value measured by the first current sensor to calculate a new supply current value, and the impedance of the impedance element to be measured is measured based on the measured both-end voltage value and the calculated new supply current value.

[0021] Therefore, according to this impedance measuring device and impedance measuring method, since the supply current value of the measurement alternating current flowing only through the impedance element to be measured is used for impedance calculation, the impedance of the impedance element to be measured can be measured with extremely high accuracy.

[0022] In the impedance measuring device according to the present invention, the first current sensor is composed of a clamp-type non-contact current sensor configured to be openable and closable.

[0023] In the impedance measuring method according to the present invention, a clamp-type non-contact current sensor configured to be openable and closable is used as the first current sensor.

[0024] According to this impedance measuring device and impedance measuring method, by using a clamp-type non-contact current sensor configured to be openable and closable as the first current sensor, the current value of the measurement alternating current supplied to the impedance element to be measured can be measured safely and easily.

[0025] In the impedance measuring device according to the present invention, the second current sensor is composed of a clamp-type non-contact current sensor configured to be openable and closable.

[0026] In the impedance measuring method according to the present invention, a clamp-type non-contact current sensor configured to be openable and closable is used as the second current sensor.

[0027] According to this impedance measurement device and impedance measurement method, by using a clamp-type non-contact current sensor configured to be openable and closable as the second current sensor, the current value of the measurement alternating current flowing through the connection line can be measured safely and easily.

[0028] In addition, the impedance measurement device according to the present invention uses any one of an electrolysis device, a fuel cell, and a lithium ion battery as the measurement object, and uses a part of a plurality of impedance elements in the measurement object as the measurement object impedance element.

[0029] In addition, the impedance measurement method according to the present invention uses any one of an electrolysis device, a fuel cell, and a lithium ion battery as the measurement object, and uses a part of a plurality of impedance elements in the measurement object as the measurement object impedance element.

[0030] According to this impedance measurement device and impedance measurement method, when a non-measurement object with an extremely small output impedance is connected in parallel with the measurement object, the impedance of the measurement object impedance element can be reliably measured.

Effect of the Invention

[0031] According to the impedance measurement device and impedance measurement method according to the present invention, by supplying a measurement alternating current to a pair of measurement current supply points defined such that one or more measurement object impedance elements among a plurality of impedance elements are included in a current path in which the measurement alternating current flows through the connection line, as a result, a supply current value of the measurement alternating current flowing through the measurement object impedance element and a voltage value across both ends of the measurement object impedance element can be measured, so that the impedance of the measurement object impedance element can be reliably measured.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0033] Hereinafter, embodiments of an impedance measurement device and an impedance measurement method using the impedance measurement device will be described with reference to the accompanying drawings.

[0034] The impedance measurement device 1 shown in FIG. 1 is an example of an impedance device that executes an impedance measurement method. In a state where a non-measurement object (a power supply device PD in the figure) is connected in parallel to a measurement object DUT configured by connecting a plurality of impedance elements in series via a connection line Lc, some of the plurality of impedance elements are used as measurement target impedance elements, and the impedance of the measurement target impedance elements can be measured.

[0035] In this case, the measurement targets can include an electrolyzer (electrolysis device) configured by electrically connecting a plurality of electrochemical cells (an example of an impedance element) in series to form a stack, an electrolytic reduction device (electrolytic reduction device) configured by electrically connecting a plurality of electrolyte membranes (an example of an impedance element) in series to form a stack, a device using an ion exchange membrane configured by electrically connecting a plurality of ion exchange membranes (an example of an impedance element) in series to form a stack, a fuel cell configured by electrically connecting a plurality of power generation cells (an example of an impedance element) in series to form a stack, and a lithium-ion battery, lead-acid battery, etc. configured by electrically connecting a plurality of battery cells (an example of an impedance element) in series to form a stack. Also, the non-measurement targets can include power supply devices such as inverter devices and converter devices, various loads such as electronic devices, and various power generation devices such as fuel cells during operation or non-operation. Hereinafter, as an example, an example will be described in which an electrolyzer is used as the device under test (DUT) for measurement, and a power supply device PD that supplies driving power to the DUT for measurement is used as a non-measurement target.

[0036] First, the measurement target will be described. As shown in FIG. 1, in this example, an electrolyzer configured by electrically connecting a plurality of electrochemical cells C1 to C10 (hereinafter, also referred to as "electrochemical cell C" when not distinguished) in series to form a stack is used as the DUT for measurement. In fact, the electrolyzer is configured by connecting dozens to hundreds of electrochemical cells C in series. However, in this example, for ease of understanding, the DUT for measurement is assumed to be composed of 10 electrochemical cells C1 to C10 electrically connected in series. In this case, in this DUT for measurement, a pair of terminals T1, T11 and terminals T2 to T10 (hereinafter, also referred to as "terminal T" when not distinguishing terminals T1 to T11) respectively connected to each connection point of each electrochemical cell C, C are provided.

[0037] (First Embodiment) Next, the configuration of the impedance measurement device 1 will be described. As shown in FIG. 1, the impedance measurement device 1 includes a measurement current output unit 2, a voltage measurement unit 3, a current sensor 4-1, a processing unit 5, an output unit 6, voltage detection probes P1 and P2, and measurement current supply probes Pi1 and Pi2.

[0038] The measurement current output unit 2 functions as a measurement current supply unit that supplies a measurement AC current to a measurement target cell as a measurement target impedance element, and generates and outputs a measurement AC current Im, which is a sine wave AC signal for measuring the impedance of the measurement target cell, in accordance with an instruction from the processing unit 5. Further, a measurement current supply line Li is connected to one output unit and the other output unit of the measurement current output unit 2, respectively. For this reason, the measurement current output unit 2 outputs the measurement AC current Im to an electrochemical cell C as a measurement target impedance element (hereinafter, the measurement target electrochemical cell C is also referred to as the "measurement target electrochemical cell C") via the measurement current supply lines Li, Li and the probes Pi1, Pi2. Further, the measurement current output unit 2 is configured to be able to vary the frequency of the measurement AC current Im, and sweeps (changes) the frequency of the measurement AC current Im in accordance with a frequency control signal Sf output from the processing unit 5 and outputs it.

[0039] The voltage measurement unit 3 measures the voltage input via the pair of probes P1 and P2, and outputs voltage value data Dv indicating the measurement value to the processing unit 5.

[0040] The current sensor 4-1 functions as a first current sensor, and for example, a current sensor as disclosed in Japanese Unexamined Patent Application Publication No. 2014-235045 can be used. It is composed of a clamp-type ammeter that can non-contact clamp a wire such as a coated metal wire. Specifically, the current sensor 4-1 includes two semi-circular magnetic cores 4a and 4b, and a magnetic detection element 4c composed of, for example, a Hall element or a fluxgate element. By operating an operation unit (not shown) to bring the magnetic core 4a and the magnetic core 4b close to each other, an annular opening 4d can be formed to clamp (insert) a wire. By operating the operation unit to separate the magnetic core 4a and the magnetic core 4b from each other, it functions as a clamp-type non-contact current sensor that can release the clamp on the clamped wire (open and close). Further, in this current sensor 4-1, the magnetic detection element 4c detects the magnetic flux generated in the magnetic cores 4a and 4b when a current flows through the wire inserted through the opening 4d, thereby measuring (detecting) the current value of the current in the frequency band from direct current to high frequency flowing through the wire, and outputting current value data Di1 indicating the measured current value. However, as the current sensor 4-1, a type of sensor that can measure the current value of a high-frequency signal excluding direct current can be adopted, or instead of the clamp-type current sensor, a current sensor configured to be non-openable and closable using an annular core can also be adopted.

[0041] The processing unit 5 is composed of, for example, a CPU, and comprehensively controls the impedance measurement device 1. Specifically, during impedance measurement, the processing unit 5 controls the measurement current output unit 2 to generate and output a measurement alternating current Im. Further, as will be described later, during impedance measurement, the processing unit 5 measures (calculates) the impedance of the measurement target electrochemical cell C.

[0042] Specifically, the processing unit 5 controls the voltage measurement unit 3 to measure the voltage between the probes P1 and P2 and output voltage value data Dv, and controls the current sensor 4-1 to measure the current flowing through the wire (in this example, the measurement current supply line Li) inserted through the opening 4d of the current sensor 4-1 and output current value data Di1. Further, the processing unit 5 inputs the voltage value data Dv output from the voltage measurement unit 3 and the current value data Di1 output from the current sensor 4-1. Further, the processing unit 5 measures (calculates) the impedance of the electrochemical cell C to be measured based on the input voltage value data Dv and current value data Di1. Specifically, the processing unit 5 calculates the alternating voltage (both-end voltage) at both ends of the electrochemical cell C to be measured as the voltage value V (both-end voltage value) based on the amplitude of the alternating voltage included in the voltage value data Dv, and calculates the current value I (supply current value) of the measurement alternating current Im flowing through the electrochemical cell C to be measured based on the amplitude of the alternating current included in the current value data Di1. Further, the processing unit 5 calculates the phase difference (θ) between the alternating voltage and the alternating current, that is, the phase difference (θ) between the alternating voltage generated at both ends of the electrochemical cell C to be measured and the alternating current flowing through the electrochemical cell C to be measured, based on the voltage value data Dv and the current value data Di1. Further, the processing unit 5 measures (calculates) the impedance of the electrochemical cell C to be measured (impedance Z = V / I, R = Z·cosθ, X = Z·sinθ) based on the voltage value (V) of the alternating voltage, the current value (I) of the measurement alternating current Im, and the phase difference (θ) calculated in this way.

[0043] Further, the processing unit 5 outputs a frequency control signal Sf to the measurement current output unit 2 in accordance with an instruction from an operation unit (not shown) to sweep the measurement alternating current Im from the low-frequency band to the high-frequency band. Further, the processing unit 5 outputs display data Dd for displaying the impedance of the measured electrochemical cell C and the frequency characteristics of the impedance such as the Nyquist plot and the Bode diagram to the output unit 6.

[0044] The output unit 6 is, for example, composed of a display device (display) such as a liquid crystal panel or an organic EL panel, and inputs the display data Dd output from the processing unit 5 to display the impedance of the measurement target electrochemical cell C and the frequency characteristics of the impedance on the screen. Note that the output unit 6 may be configured with an interface device that performs data communication with an external device instead of the display device, and adopts a configuration in which impedance data indicating the impedance of the measurement target electrochemical cell C and the frequency characteristics of the impedance is output to this external device.

[0045] The probes P1 and P2 are contact-type probes configured to measure the AC voltage as the voltage across the terminals T and T when the measurement AC current Im is supplied to the measurement target electrochemical cell C with each tip connected (contacted) to the terminal T of the measurement target DUT. Also, the probes Pi1 and Pi2 are contact-type probes configured to supply the measurement AC current Im with each tip connected (contacted) to the terminal T of the measurement target DUT.

[0046] Next, an impedance measurement method for measuring (calculating) the impedance of the measurement target electrochemical cell C using the impedance measurement device 1 will be described with reference to the drawings. It is assumed that the power supply device PD is already connected in parallel to the measurement target DUT via the connection line Lc connected to the terminals T1 and T11 of the measurement target DUT. Also, a measurement method for measuring the impedance between both ends of the two electrochemical cells C4 and C5 in the measurement target DUT as the measurement target electrochemical cell C will be described.

[0047] First, connect the probes Pi1 and Pi2 to a pair of terminals T and T. In this case, connect the probes Pi1 and Pi2 to a pair of measurement current supply points Po1 and Po2 defined such that an alternating current Im for measuring the current value I2 flows through the connection line Lc and one or more of the plurality of electrochemical cells C are included in the current path IR2 described later. As shown in FIG. 1, as an example, in this example, the probes Pi1 and Pi2 are connected to the terminals T3 and T8 of the device under test (DUT) as a pair of measurement current supply points Po1 and Po2. Note that as long as one or more of the plurality of electrochemical cells C are included in the current path IR2, the probe Pi1 can be connected to the terminal T2 instead of the terminal T3, and the probe Pi2 can be connected to the terminals T7 or T9 to T10 instead of the terminal T8. Also, the probe Pi1 can be connected to the terminal T1 instead of the terminal T3, and the probe Pi2 can be connected to the terminals T7 or T9 to T10 instead of the terminal T8. That is, connect the probes Pi1 and Pi2 to the terminals T and T such that one or more electrochemical cells C are included in either the current path IR2 connecting the probe Pi1 and the power supply device PD or the current path IR2 connecting the probe Pi2 and the power supply device PD.

[0048] Next, a part (in this example, the electrochemical cells C4 and C5) of a plurality of other impedance elements (in this example shown in FIG. 1, the electrochemical cells C3 to C7) excluding the one or more electrochemical cells C (in this example shown in FIG. 1, the electrochemical cells C1, C2, C8 to C10) is used as the electrochemical cell C to be measured, and in order to measure the voltage value V of the voltage across both ends of the electrochemical cells C4 and C5 which are the electrochemical cells C to be measured, connect the probes P1 and P2 to a pair of terminals T4 and T6 which function as a pair of voltage measurement points Po3 and Po4, respectively.

[0049] Subsequently, a current sensor 4-1 is arranged at a position between one output terminal of the measurement current output unit 2 in the measurement current supply line Li and the terminal T3 (the measurement current supply line Li is clamped by the current sensor 4-1). At this time, an operation unit (not shown) is operated so that the magnetic cores 4a and 4b of the current sensor 4-1 are separated from each other and the opening 4d is in an open state. Next, the measurement current supply line Li is inserted through the opening 4d of the current sensor 4-1. Then, the operation unit (not shown) is operated so that the magnetic cores 4a and 4b of the current sensor 4-1 are brought close to each other and the opening 4d is in a closed state. Thereby, the measurement current supply line Li is clamped by the current sensor 4-1.

[0050] Next, an off-diagram measurement start switch is operated. Thereby, the processing unit 5 outputs a frequency control signal Sf to control the measurement current output unit 2 to output a measurement AC current Im. At this time, the measurement AC current Im of the current value I0 output from the measurement current output unit 2 is split into the measurement AC current Im of the current value I1 flowing through the current path IR1 composed of one output terminal of the measurement current output unit 2, the measurement current supply line Li, the probe Pi1, the terminal T3 of the DUT under measurement, the electrochemical cells C3 to C7, the terminal T8, the probe Pi2, the measurement current supply line Li, and the other output terminal of the measurement current output unit 2, and the measurement AC current Im of the current value I2 flowing through the current path IR2 composed of one output terminal of the measurement current output unit 2, the measurement current supply line Li, the probe Pi1, the terminal T3 of the DUT under measurement, the electrochemical cells C2 and C1, the terminal T1 of the DUT under measurement, the connection line Lc, the power supply device PD, the connection line Lc, the terminal T11 of the DUT under measurement, the electrochemical cells C10 to C8, the terminal T8, the probe Pi2, the measurement current supply line Li, and the other output terminal of the measurement current output unit 2. Also, the DC of the current value ID output from the power supply device PD flows through the DUT under measurement from the terminal T1 to the terminal T11 of the DUT under measurement. That is, the connection line Lc is an active line through which a DC current flows.

[0051] In this state, the processing unit 5 controls the voltage measurement unit 3 to measure the voltage value V at both ends of the electrochemical cells C4 and C5 connected between the probes P1 and P2, and outputs voltage value data Dv. At this time, the voltage measurement unit 3 measures the voltage across both ends of the electrochemical cells C4 and C5 generated by the measurement AC current Im of the current value I1 flowing through the current path IR1 including the electrochemical cells C3 to C7 inside the device under test (DUT), and outputs voltage value data Dv indicating the voltage value V to the processing unit 5.

[0052] Also, the current sensor 4-1 measures the current value I0 of the measurement AC current Im flowing through the measurement current supply line Li inserted (clamped) into the opening 4d, and outputs current value data Di1. In this case, the current value I0 of the measurement AC current Im measured by the current sensor 4-1 is the current value obtained by adding the current value I1 of the measurement AC current Im flowing through the current path IR1 and the current value I2 of the measurement AC current Im flowing through the current path IR2.

[0053] In this state, the number of electrochemical cells C included in the current path IR1 (in this example, 2) is sufficiently smaller than the number of electrochemical cells C included in the current path IR2 (in this example, 8). For this reason, the impedance of the measurement AC current Im with respect to the current path IR2 becomes sufficiently larger than the impedance of the measurement AC current Im with respect to the current path IR1, and as a result, the current value I1 of the measurement AC current Im flowing through the current path IR1 becomes sufficiently larger than the current value I2 of the measurement AC current Im flowing through the current path IR2. In this case, in the conventional impedance measurement device 1X, since the measurement AC current Im cannot be sufficiently passed through the electrochemical cell C to be measured, the voltage across both ends of the electrochemical cell C to be measured cannot be measured, and as a result, the impedance of the electrochemical cell C to be measured cannot be measured. On the other hand, in this impedance measurement device 1, since the measurement AC current Im can be sufficiently passed through the electrochemical cell C to be measured, the voltage across both ends of the electrochemical cell C to be measured can be reliably measured, and as a result, the impedance of the electrochemical cell C to be measured can be reliably measured.

[0054] Next, the processing unit 5 inputs the voltage value data Dv output from the voltage measurement unit 3 and the current value data Di1 output from the current sensor 4-1. Further, the processing unit 5 measures (calculates) the impedance of the electrochemical cells C4 and C5 based on the input voltage value data Dv and the current value data Di1.

[0055] Specifically, the processing unit 5 calculates the AC voltage, which is the voltage across the electrochemical cells C4 and C5, as the voltage value (V) based on the amplitude of the measurement AC current Im included in the voltage value data Dv. Further, the processing unit 5 calculates the current value (I) of the measurement AC current Im flowing through the electrochemical cells C4 and C5 based on the amplitude of the measurement AC current Im included in the corrected current value data Di1. Also, the processing unit 5 calculates the phase difference (θ) between the AC voltage and the AC current based on the voltage value data Dv and the current value data Di1, that is, the phase difference (θ) between the AC voltage generated across the measurement target electrochemical cell C, which is the electrochemical cells C4 and C5, and the AC current (measurement AC current Im) flowing through the measurement target electrochemical cell C, which is the electrochemical cells C4 and C5. Further, the processing unit 5 measures (calculates) the impedance (impedance Z = V / I, R = Z·cosθ, X = Z·sinθ) of the measurement target electrochemical cell C, which is the electrochemical cells C4 and C5, based on the voltage value (V), the current value (I), and the phase difference (θ) calculated in this way.

[0056] In this case, in the impedance measurement by this impedance measurement device 1, since the current value I1 of the measurement AC current Im flowing through the measurement target electrochemical cell C (in this example, the electrochemical cells C4 to C5) increases, the voltage value V of the voltage across the measurement target electrochemical cell C increases. Therefore, since the ratio (S / N) of the signal level (S) of the measurement AC current Im to the noise level (N) of the voltage value V of the voltage across measured by the voltage measurement unit 3 increases, the impedance of the measurement target electrochemical cell C is measured with high accuracy in the impedance calculation process performed by the processing unit 5.

[0057] Further, the processing unit 5 sweeps the frequency of the measurement AC current Im by outputting a frequency control signal Sf to the measurement current output unit 2. Then, at a plurality of frequencies, the processing unit 5 measures (calculates) the impedance of each of the electrochemical cells C4 and C5, which are the electrochemical cells C to be measured, as described above. Next, the processing unit 5 acquires the frequency characteristics of the impedance of the electrochemical cells C4 and C5, which are the electrochemical cells C to be measured, at a plurality of frequencies. In this case, as the frequency characteristics, the processing unit 5 acquires a Cole-Cole plot indicating the characteristics of the impedance of the electrochemical cell C with respect to the frequency, and a Bode diagram indicating the characteristics of the gain and phase with respect to the frequency. Thereafter, the processing unit 5 outputs display data Dd to the output unit 6 to cause the display device of the output unit 6 to display the measured impedances of the electrochemical cells C4 and C5, the acquired Cole-Cole plot, and the Bode diagram. Thus, the measurement process of the impedance of the electrochemical cells C4 and C5, which are the electrochemical cells C to be measured, by the processing unit 5 is completed.

[0058] As described above, in this impedance measurement apparatus 1 and impedance measurement method, the measurement AC current Im is supplied to a pair of measurement current supply points Po1 and Po2 defined such that one or more of the plurality of electrochemical cells C are included in the current path IR2 in which the measurement AC current Im flows through the connection line Lc. As a result, a part of the plurality of electrochemical cells C other than the one or more electrochemical cells C is used as the electrochemical cells C to be measured (in this example, the electrochemical cells C4 and C5). The measurement AC current Im is supplied to the electrochemical cells C to be measured, the voltage value V at both ends of the electrochemical cells C to be measured is measured, and the impedance of the electrochemical cells C to be measured is measured based on the measured voltage value V and the current value I0 of the measurement AC current Im supplied to the electrochemical cells C to be measured.

[0059] Therefore, according to this impedance measurement apparatus 1 and impedance measurement method, even when a non-measurement object with low impedance (in this example, the power supply device PD) is connected in parallel to a DUT (Device Under Test) configured by connecting a plurality of electrochemical cells C1 to C10 in series, some of the plurality of electrochemical cells C1 to C10 (in this example, the electrochemical cells C4 and C5) are used as the measurement target electrochemical cell C, and a measurement AC current Im with a sufficiently large current value I1 can be supplied to the measurement target electrochemical cell C. As a result, the voltage value V of the voltage across the measurement target electrochemical cell C when the measurement AC current Im is supplied to the measurement target electrochemical cell C and the supply current value of the measurement AC current Im flowing through the measurement target electrochemical cell C (the current value I1 that is approximately equal to the current value I0) can be measured. Therefore, the impedance of the measurement target electrochemical cell C can be reliably measured.

[0060] Also, in reality, since dozens to hundreds of impedance elements (in this example, the electrochemical cells C) are connected in series to form the DUT (in this example, the electrolysis device), when measuring the impedance of a small number of measurement target electrochemical cells C (in this example, the measurement target electrochemical cell C), the current value I2 of the measurement AC current Im flowing through the current path IR2 including a very large number of electrochemical cells C is extremely small, and the measurement AC current Im with a large current value I1 that is approximately equal to the current value I0 flows through the current path IR1 which is the measurement path. Therefore, the impedance of the measurement target electrochemical cell C can be measured more reliably and accurately.

[0061] Also, according to this impedance measurement apparatus 1 and impedance measurement method, by using a clamp-type non-contact current sensor configured to be openable and closable as the current sensor 4-1, the current value (supply current: the current value I1 approximated to the current value I0) of the measurement AC current Im supplied to the measurement target electrochemical cell C (in this example, the electrochemical cells C4 and C5) can be measured safely and easily.

[0062] Further, according to this impedance measuring apparatus 1 and impedance measuring method, when any one of an electrolyzer, a fuel cell, and a lithium ion battery (in this example, the electrolyzer) is used as a device under test (DUT) to be measured, and a part of a plurality of electrochemical cells C1 to C10 in the DUT to be measured (in this example, electrochemical cells C4 and C5) is used as a measurement target electrochemical cell C to measure the impedance, when a non-measurement target (in this example, a power supply device PD) having an extremely small output impedance is connected in parallel with the DUT to be measured, the impedance of the measurement target electrochemical cell C (in this example, electrochemical cells C4 and C5) can be reliably measured.

[0063] Further, according to this impedance measuring apparatus 1 and impedance measuring method, by obtaining the frequency characteristics of the impedance of the measurement target electrochemical cell C (in this example, electrochemical cells C4 and C5) at a plurality of frequencies, the performance and deterioration of the measurement target electrochemical cell C can be discriminated.

[0064] Further, according to this impedance measuring apparatus 1 and impedance measuring method, by obtaining either a Nyquist plot or a Bode diagram as the frequency characteristics, the performance and deterioration of the measurement target electrochemical cell C can be discriminated with high accuracy.

[0065] (Second Embodiment) Next, with reference to FIG. 2, another method for defining a pair of measurement current supply points Po1 and Po2 will be described. Hereinafter, for the processing content by the impedance measuring apparatus 1 and the impedance measuring method, the same processing content and measuring method as those in the above-described first embodiment will not be described repeatedly.

[0066] Regarding the pair of measurement current supply points Po1 and Po2, as long as one or more of the plurality of electrochemical cells C are included in the current path IR2 in which the measurement alternating current Im (in this example, the measurement alternating current Im for the current value I2) flows through the connection line Lc, the pair of measurement current supply points Po1 and Po2 can be defined at the same electrical position as the pair of voltage measurement points Po3 and Po4.

[0067] As shown in FIG. 2, when the electrochemical cell C4 is used as the electrochemical cell C to be measured, probes P1 and P2 are connected with two terminals T4 and T5 connected to both ends of the electrochemical cell C4 as a pair of voltage measurement points Po3 and Po4. Also, a position electrically the same as the pair of voltage measurement points Po3 and Po4 is defined as a pair of measurement current supply points Po1 and Po2, and probes Pi1 and Pi2 are connected to the pair of measurement current supply points Po1 and Po2 (in this example, terminals T4 and T5). Next, in the same manner as in the first embodiment, the measurement current supply line Li is clamped by the current sensor 4-1.

[0068] Next, an off-diagram measurement start switch is operated. As a result, in the same manner as in the first embodiment, when the processing unit 5 executes the above processing, the measurement AC current Im of the current value I0 output from the measurement current output unit 2 is the measurement AC current Im of the current value I3 flowing through the current path IR3 composed of one output terminal of the measurement current output unit 2, the measurement current supply line Li, the probe Pi1, the terminal T4 (measurement current supply point Po1) of the DUT to be measured, the electrochemical cell C4, the terminal T5 (measurement current supply point Po2), the probe Pi2, the measurement current supply line Li, and the other output terminal of the measurement current output unit 2, and the measurement AC current Im of the current value I4 flowing through the current path IR4 composed of one output terminal of the measurement current output unit 2, the measurement current supply line Li, the probe Pi1, the terminal T4 (measurement current supply point Po1) of the DUT to be measured, the electrochemical cells C3 to C1, the terminal T1 of the DUT to be measured, the connection line Lc, the power supply device PD, the connection line Lc, the terminal T11 of the DUT to be measured, the electrochemical cells C10 to C5, the terminal T5 (measurement current supply point Po2), the probe Pi2, the measurement current supply line Li, and the other output terminal of the measurement current output unit 2. Also, the DC of the current value ID output from the power supply device PD flows through the DUT to be measured from the terminal T1 to the terminal T11.

[0069] In this state, the voltage measurement unit 3 measures the voltage value V of the voltage across the electrochemical cell C4 by allowing the measurement alternating current Im for measuring the current value I3 to flow through the current path IR3 including the electrochemical cell C4, and outputs voltage value data Dv indicating the voltage value V to the processing unit 5. Further, the current sensor 4-1 measures the current value I0 of the measurement alternating current Im flowing through the measurement current supply line Li inserted (clamped) into the opening 4d and outputs current value data Di1.

[0070] Next, the processing unit 5 inputs the voltage value data Dv output from the voltage measurement unit 3 and the current value data Di1 output from the current sensor 4-1. Further, the processing unit 5 measures (calculates) the impedance of the electrochemical cell C4 based on the input voltage value data Dv and current value data Di1. Thereafter, the processing unit 5 outputs display data Dd to the output unit 6 to cause the display device of the output unit 6 to display the calculated impedance. Thus, the measurement process of the impedance of the electrochemical cell C4, which is the electrochemical cell C to be measured by the processing unit 5, is completed.

[0071] Thus, in this impedance measuring apparatus 1 and impedance measuring method, by defining a pair of measurement current supply points Po1 and Po2 at electrically the same positions as a pair of voltage measurement points Po3 and Po4 that measure the voltage value V at both ends of the electrochemical cell C to be measured (in this example, the electrochemical cell C4), and supplying the measurement alternating current Im, it is possible to include the most electrochemical cells C in the current path IR4 that does not include the electrochemical cell C to be measured. Therefore, even if the power supply device PD has a low impedance, the impedance of the entire current path IR4 can be made sufficiently large. For this reason, according to this impedance measuring apparatus 1 and impedance measuring method, it is possible to minimize the current value I4 of the measurement alternating current Im that shunts from the measurement alternating current Im for measuring the current value I0 and flows through the connection line Lc. Correspondingly, the current value I3 of the measurement alternating current Im that shunts from the measurement alternating current Im for measuring the current value I0 and flows through the electrochemical cell C to be measured (in this example, the electrochemical cell C4) can be maximized. As a result, the voltage value V at both ends of the electrochemical cell C to be measured can be made sufficiently large. Thereby, according to this impedance measuring apparatus 1 and impedance measuring method, since the ratio (S / N) of the signal level (S) to the noise level (N) of the measured voltage across both ends can be sufficiently increased, the impedance of the electrochemical cell C to be measured can be measured with sufficiently high accuracy.

[0072] (Third Embodiment) Next, with reference to FIG. 3, the impedance measuring apparatus 1A will be described. Note that redundant descriptions of the same components and the same operations as those of the impedance measuring apparatus 1 will be omitted.

[0073] The impedance measuring apparatus 1A is configured to be able to measure the impedance of the electrochemical cell C to be measured with higher accuracy than the measurement accuracy of the impedance measuring apparatus 1, in addition to the configuration of the impedance measuring apparatus 1, and includes a current sensor 4-2 that functions as a second current sensor. In this case, the current sensor 4-2 is configured identically to the current sensor 4-1 and is a clamp-type ammeter that can non-contact clamp a wire such as a coated metal wire.

[0074] When measuring the impedance of the electrochemical cell S to be measured, the processing unit 5 calculates (obtains) the current value I1 of the measurement alternating current Im flowing through the electrochemical cell C to be measured by subtracting the current value I2 of the measurement current Im after shunting measured by the current sensor 4-2 from the current value I0 of the measurement current Im before shunting measured by the current sensor 4-1. Further, the processing unit 5 calculates (measures) the impedance of the electrochemical cell C to be measured based on the voltage value V measured by the voltage measurement unit 3 and the calculated current value I1. Therefore, in the impedance calculation, since the current value I1 of the measurement alternating current Im flowing only through the electrochemical cells C4 and C5 to be measured is used, the impedance can be calculated with the highest accuracy.

[0075] Next, with reference to FIG. 3, an impedance measurement method for measuring (calculating) the impedance of the electrochemical cell C to be measured using the impedance measurement device 1A will be described. It is assumed that the power supply device PD is already connected in parallel to the DUT to be measured via the connection line Lc connected to the terminals T1 and T11 of the DUT to be measured. Further, as an example, a measurement method for measuring the impedance between both ends of the two electrochemical cells C4 and C5 in the DUT to be measured, with the two electrochemical cells C4 and C5 in the DUT to be measured as the electrochemical cell C to be measured, will be described.

[0076] First, in the same manner as in the first embodiment described above, the probes Pi1 and Pi2 are respectively connected to a pair of terminals T3 and T8, and the probes P1 and P2 are respectively connected to a pair of terminals T4 and T6. In this case, in the same manner as in the second embodiment described above, a pair of measurement current supply points Po1 and Po2 may be defined at positions electrically the same as the pair of voltage measurement points Po3 and Po4. Next, the current sensor 4-1 is arranged at a position between one output terminal of the measurement current output unit 2 and the terminal T3 (the current sensor 4-1 clamps the measurement current supply line Li), and the current sensor 4-2 is arranged at a position between the terminal T1 of the DUT to be measured and one output terminal of the power supply device PD (the current sensor 4-2 clamps the connection line Lc).

[0077] Next, an off-diagram measurement start switch is operated. As a result, the processing unit 5 outputs a frequency control signal Sf to control the measurement current output unit 2 to output a measurement alternating current Im. At this time, the measurement alternating current Im of the current value I0 output from the measurement current output unit 2 is divided into the measurement alternating current Im of the current value I1 flowing through the current path IR1 and the measurement alternating current Im of the current value I2 flowing through the current path IR2. Also, the direct current of the current value ID output from the power supply device PD flows through the inside of the DUT from the terminal T1 to the terminal T11 of the DUT to be measured.

[0078] In this state, the processing unit 5 controls the voltage measurement unit 3 to measure the voltage value V at both ends of the electrochemical cells C4 and C5 connected between the probes P1 and P2 and output voltage value data Dv. Also, the current sensor 4-1 measures the current value I0 of the measurement alternating current Im flowing through the measurement current supply line Li inserted (clamped) into the opening 4d and outputs current value data Di1. Also, the current sensor 4-2 measures the current value I2 of the measurement alternating current Im flowing through the connection line Lc inserted (clamped) into the opening 4d and outputs current value data Di2.

[0079] Next, the processing unit 5 inputs the voltage value data Dv output from the voltage measurement unit 3, the current value data Di1 output from the current sensor 4-1, and the current value data Di2 output from the current sensor 4-2. Also, the processing unit 5 measures (calculates) the impedance of the electrochemical cells C4 and C5 based on the input voltage value data Dv and current value data Di1 and Di2.

[0080] Specifically, first, the processing unit 5 corrects the current value indicated by the current value data Di2 by subtracting the current value ID of the direct current from the data indicating the current value (the sum of the current value I2 of the measurement alternating current Im and the current value ID of the direct current) included in the current value data Di2. As a result, the current value indicated by the corrected current value data Di2 is the current value I2 of the measurement alternating current Im flowing through the current path IR2. When no direct current is flowing through the DUT under measurement and when the current sensor 4-2 is a current sensor that does not detect direct current, since the current value indicated by the current value data Di2 is only the current value I2 of the measurement alternating current Im, the process of correcting the current value by subtracting the current value ID of the direct current from the current value data Di2 becomes unnecessary.

[0081] Next, the processing unit 5 calculates (computes) the current value I1 as a new supply current value by subtracting the current value I2 of the measurement alternating current Im after shunting indicated by the current value data Di2 from the current value I0 of the measurement alternating current Im before shunting indicated by the current value data Di1. Subsequently, the processing unit 5 calculates the alternating voltage, which is the voltage across the electrochemical cells C4 and C5, as the voltage value (V) based on the amplitude of the measurement alternating current Im included in the voltage value data Dv. Further, the processing unit 5 calculates the current value (I) of the measurement alternating current Im flowing through the electrochemical cells C4 and C5 based on the amplitude of the measurement alternating current Im of the calculated current value I1. Also, the processing unit 5 calculates the phase difference (θ) between the alternating voltage and the alternating current, that is, the phase difference (θ) between the alternating voltage generated across the electrochemical cells C4 and C5, which are the measurement target electrochemical cells C, and the alternating current (measurement alternating current Im) flowing through the electrochemical cells C4 and C5, which are the measurement target electrochemical cells C, based on the voltage value data Dv and the calculated current value I1. Further, the processing unit 5 measures (computes) the impedance (impedance Z = V / I, R = Z·cosθ, X = Z·sinθ) of the electrochemical cells C4 and C5, which are the measurement target electrochemical cells C, based on the voltage value (V), the current value (I), and the phase difference (θ) calculated in this way.

[0082] In this case, the calculated current value I1 is the current value of the measurement alternating current Im that flows only through the electrochemical cells C4 and C5 to be measured. Therefore, in the impedance measurement by this impedance measurement device 1A, the impedance of the electrochemical cell C to be measured (in this example, the electrochemical cells C4 to C5) is measured with the highest accuracy. As described above, the measurement process of the impedance of the electrochemical cells C4 and C5, which are the electrochemical cells C to be measured by the processing unit 5, is completed.

[0083] Thus, in this impedance measurement device 1A and impedance measurement method, the current value I2 of the measurement alternating current Im flowing through the connection line Lc is measured by the current sensor 4-2, and the current value I2 measured by the current sensor 4-2 is subtracted from the current value I0 measured by the current sensor 4-1 to calculate a new supply current value (current value I1). Based on the measured voltage value V and the calculated current value I1, the impedance of the electrochemical cell C to be measured (in this example, the electrochemical cells C4 and C5) is measured.

[0084] Therefore, according to this impedance measurement device 1A and impedance measurement method, since the current value I1 of the measurement alternating current Im that flows only through the electrochemical cells C4 and C5 to be measured is used for impedance calculation, the impedance of the electrochemical cell C to be measured can be measured with extremely high accuracy.

[0085] Further, according to this impedance measurement device 1A and impedance measurement method, by using a clamp-type non-contact current sensor configured to be openable and closable as the current sensor 4-2, the current value I2 of the measurement alternating current Im flowing through the connection line Lc can be measured safely and easily.

[0086] Note that the present invention is not limited to the above-described embodiments and can be modified as appropriate. For example, in each of the above embodiments, an alternating current is used as the measurement alternating current Im. However, when no direct current flows between the device under test (DUT) and the power supply device PD, a direct current can be used as the measurement current. Further, in the above embodiments, the number of the electrochemical cells C to be measured is set to one or two, but the number is not limited to this and can be three or more. Furthermore, in the above embodiments, an example in which an electrolysis device is used as the DUT has been described. However, a fuel cell or a lithium ion can be used as the DUT, and a load can be set as a non-measurement object.

[0087] In addition, although an example in which the voltage measurement unit 3 outputs voltage value data Dv has been described, a configuration can be adopted in which the voltage measurement unit 3 outputs a voltage measurement signal that is an analog signal, and the processing unit 5 measures (calculates) impedance based on the input voltage measurement signal. Similarly, although an example in which the current sensors 4-1 and 4-2 output current value data Di1 and Di2 has been described, a configuration can be adopted in which the current sensors 4-1 and 4-2 output current measurement signals that are analog signals, and the processing unit 5 measures (calculates) impedance based on the input current measurement signals.

Industrial Applicability

[0088] According to the present invention, as a result of supplying a measurement alternating current to the impedance element to be measured, it is possible to measure the voltage value at both ends of the impedance element to be measured and the supply current value of the measurement alternating current flowing through the impedance element to be measured. Therefore, the impedance of the impedance element to be measured can be reliably measured. Thereby, the present invention can be widely applied to such an impedance measurement device and impedance measurement method for impedance measurement.

Explanation of Reference Numerals

[0089] 1, 1A Impedance measurement device 2 Current output unit 3 Voltage measurement unit 4-1, 4-2 Current sensors 5 Processing Unit C1 to C10 Electrochemical Cells Di1, Di2 Current Value Data Dv Voltage Value Data Lc Connection Line Li Measurement Current Supply Line DUT Device Under Test P1, P2 Measurement Current Supply Points P3, P4 Voltage Measurement Points PD Power Supply

Claims

1. A measurement current supply unit that supplies a measurement current to a plurality of impedance elements, in a state where a non-measurement object is connected in parallel via a connection line to a measurement object configured by connecting the plurality of impedance elements in series; A voltage measurement unit that measures both-end voltage values at both ends of the impedance element when the measurement current is being supplied; A first current sensor that measures a supply current value of the measurement current supplied to the impedance element; An impedance measurement device comprising a processing unit that calculates the impedance of the impedance element based on the measured both-end voltage value and the supply current value, wherein the measurement current supply unit supplies the measurement current to a pair of measurement current supply points defined such that one or more of the plurality of impedance elements are included in a current path through which the measurement current flows in the connection line, thereby using, as measurement target impedance elements, some of the plurality of impedance elements other than the one or more impedance elements, and supplying the measurement current to the measurement target impedance elements; the voltage measurement unit measures the both-end voltage value of the measurement target impedance element; the processing unit calculates the impedance of the measurement target impedance element based on the measured both-end voltage value and the supply current value.

2. The impedance measurement device according to claim 1, wherein the measurement current supply unit supplies the measurement current to the pair of measurement current supply points defined at positions electrically the same as a pair of voltage measurement points for measuring the both-end voltage of the measurement target impedance element.

3. The impedance measurement device according to claim 1, further comprising a second current sensor that measures a current value of the measurement current flowing through the connection line, wherein the processing unit calculates a new supply current value by subtracting the current value measured by the second current sensor from the supply current value measured by the first current sensor, and calculates the impedance of the measurement target impedance element based on the measured both-end voltage value and the calculated new supply current value.

4. The impedance measurement device according to claim 1, wherein the first current sensor is a clamp-type non-contact current sensor configured to be openable and closable.

5. The impedance measuring device according to claim 3, wherein the second current sensor is a clamp-type non-contact current sensor configured to be openable and closable.

6. The impedance measuring device according to any one of claims 1 to 5, wherein any one of an electrolysis device, a fuel cell, and a lithium ion battery is the measurement target, and a part of a plurality of impedance elements in the measurement target is the measurement target impedance element.

7. An impedance measuring method for measuring the impedance of an impedance element based on the measured voltage value across both ends and the supply current value, in a state where a non-measurement target is connected in parallel via a connection line to a measurement target configured by connecting a plurality of impedance elements in series, while supplying a measurement current to the plurality of impedance elements, measuring the voltage value across both ends of the impedance element when the measurement current is being supplied, and measuring the supply current value of the measurement current supplied to the impedance element by a first current sensor, comprising: supplying the measurement current to a pair of measurement current supply points defined such that one or more of the plurality of impedance elements are included in a current path through which the measurement current flows in the connection line, thereby using a part of the plurality of impedance elements other than the one or more impedance elements as measurement target impedance elements and supplying the measurement current to the measurement target impedance elements; measuring the voltage value across both ends of the measurement target impedance element; an impedance measuring method for measuring the impedance of the measurement target impedance element based on the measured voltage value across both ends and the supply current value.

8. The impedance measuring method according to claim 7, wherein the pair of measurement current supply points are defined at positions electrically the same as a pair of voltage measurement points for measuring the voltage across both ends of the measurement target impedance element, and the measurement current is supplied.

9. The current value of the measurement current flowing through the connection line is measured by a second current sensor, and a new supply current value is calculated by subtracting the current value measured by the second current sensor from the supply current value measured by the first current sensor. The impedance of the impedance element to be measured is measured based on the measured voltage value across both ends and the calculated new supply current value. The impedance measurement method according to claim 7.

10. The impedance measurement method according to claim 7, wherein a clamp-type non-contact current sensor configured to be openable and closable is used as the first current sensor.

11. The impedance measurement method according to claim 9, wherein a clamp-type non-contact current sensor configured to be openable and closable is used as the second current sensor.

12. The impedance measurement method according to any one of claims 7 to 11, wherein any one of an electrolysis device, a fuel cell, and a lithium ion battery is the measurement target, and a part of a plurality of impedance elements in the measurement target is the impedance element to be measured.

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