Impedance measuring apparatus and impedance measuring method

Abstract

To measure impedance of a measuring object impedance element when a measured object is parallel connected to a measuring object including a plurality of series connected impedance elements.SOLUTION: An impedance measuring apparatus comprises: a measurement current outputting part 3 that, in a state where a power supply device PD is parallel connected to a measuring object DUT, supplies measurement AC current Im to some electrochemical cells C1-C5 as a measuring object cell; a current sensor 5-1 that measures a supply current value of the measurement AC current Im; and a processing part 6 that calculates impedance of the measuring object cell on the basis of the supply current value and a voltage value of opposite ends voltage of the measuring object cell. The measurement current outputting part 3 supplies the measurement AC current Im to the measuring object cell through a measurement current supply line Li connected to a measurement current supply point Ps1 and a measurement current supply point Ps3 so as to include the measuring object cell between the measurement current supply points Ps1 and Ps3. The current sensor 5-1 is arranged between a connection point Pc1 and the measurement current supply point Ps1, and the electrochemical cell C1.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 or all of a plurality of impedance elements in a state where a non-measurement object is connected in parallel to a measurement object configured by connecting a plurality of impedance elements in series via a connection line. [Background technology]

[0002] The impedance measuring device disclosed in the following patent document is known as an impedance measuring device capable of measuring the impedance of a measurement object in a state where a non-measurement object is connected in parallel to the measurement object via a connection line. This impedance measuring device is configured to be capable of measuring the internal impedance of a secondary battery in a state where a load as a non-measurement object is connected in parallel to the secondary battery as the measurement object via a power supply line as a connection line. Specifically, this impedance measuring device is configured to include an AC current supply unit, an AC voltage detection unit, an AC current detection unit, an A / D conversion unit, and a calculation control unit. In this case, the AC current detection unit is configured to include a clamp-type current sensor.

[0003] When the internal impedance of a secondary battery is measured using this impedance measuring device, first, a power line is inserted into the opening of a clamp-type current sensor in the AC current detection unit. In this state, the AC current supply unit supplies a measurement AC current between the power lines. As a result, a part of the measurement AC current flows through the secondary battery. In addition, the remaining part of the measurement AC current flows through the load, and a DC current output from the secondary battery flows. In this case, the current sensor of the AC current detection unit detects the AC current flowing through the power line passing through the opening, and outputs a negative feedback current according to the AC current value of the AC current. At this time, an AC voltage is generated across the detection resistor due to the feedback current flowing. Next, the A / D conversion unit A / D converts the AC current data indicating the AC current value, and outputs it to the calculation control unit. In addition, the AC voltage detection unit detects the voltage across both ends of the secondary battery, and outputs AC voltage data indicating the voltage value of the voltage across both ends to the calculation control unit. Next, the calculation control unit calculates the internal impedance of the secondary battery based on the AC current value indicated by the input AC current data and the voltage value across the secondary battery indicated by the input AC voltage data. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-251625 A (pages 3-8, Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above impedance measuring device has the following problems. As conceptually shown in FIG. 5, for example, an electrolysis device (electrolysis device) that generates hydrogen and oxygen is used as the measurement target DUT, and the problems when measuring the impedance of the measurement target DUT in an operating state using the above impedance measuring device 1X will be specifically described. In this case, the measurement target DUT is connected in parallel with a power supply device PD that supplies a direct current to the measurement target DUT via a power supply line Lp as a connection line. Therefore, when measuring the impedance of the measurement target DUT in operation, the AC current supply unit U1 supplies a measurement AC current Im to the measurement target DUT via the measurement current supply line Li and the terminals T1 and T11 at both ends of the measurement target DUT. In this state, the current sensor U4 measures the current value of the measurement AC current Im flowing through the measurement target DUT, and the AC voltage detection unit U2 detects the voltage value of the AC voltage generated between the terminals T1 and T11 of the measurement target DUT. Next, the calculation control unit U3 measures the impedance of the measurement target DUT based on the current value of the measurement AC current Im detected by the current sensor U4 and the voltage value of the AC voltage measured by the AC voltage detection unit U2.

[0006] In this case, the impedance of the power supply device PD in the operating state is extremely small compared to the impedance of the DUT under test. Therefore, in the measurement state shown in FIG. 5, the terminals T1 and T11 of the DUT under test are substantially short-circuited by the power line Lp. Therefore, even if the AC current supply unit UI outputs the measurement AC current Im, almost all of the measurement AC current Im is shunted to the power supply device PD, and the measurement AC current Im does not flow to the DUT under test. Therefore, the voltage value of the AC voltage between the terminals T1 and T11 of the DUT under test becomes almost zero volts. As a result, the AC voltage detection unit U2 cannot detect the AC voltage generated at both ends of the DUT under test. Therefore, the impedance measurement device 1X has a problem that it cannot measure the impedance of the DUT under test when a low-impedance object to be measured is connected in parallel to the DUT under test.

[0007] The present invention has been made in consideration of such problems, and has as its main object to provide an impedance measuring device and an impedance measuring method that are capable of measuring the impedance of some or all of a plurality of impedance elements in a state in which a non-measurement object is connected in parallel to a measurement object configured by connecting a plurality of impedance elements in series via a connection line. [Means for solving the problem]

[0008] In order to achieve the above object, an impedance measuring device according to the present invention includes a measurement target configured to include a plurality of impedance elements connected in series between a pair of terminals, and a non-measurement target connected in parallel via a pair of connection lines connected to a pair of connection points defined on the side of the pair of terminals, the impedance measuring device comprising: a measurement current supply unit that supplies a measurement AC current to the measurement target impedance element via measurement current supply lines that are respectively connected to one measurement current supply point and the other measurement current supply point defined on the side of any one of the pair of terminals, a first current sensor that measures a supply current value of the measurement AC current supplied to the measurement target impedance element; a voltage measurement unit that measures a voltage value of a voltage across both ends of the measurement target impedance element; and a processing unit that calculates the impedance of the impedance element to be measured based on the supply current value and the voltage value of the voltage between both ends, wherein the measurement current supply unit supplies the measurement AC current to the impedance element to be measured via the pair of measurement current supply lines connected to one measurement current supply point and the other measurement current supply point that are defined so that the impedance element to be measured is included in a current path between the one measurement current supply point and the other measurement current supply point that is connected to a connection point of any two of the multiple impedance elements that are connected in series, and the first current sensor is arranged between a connection point defined on the side of any one of the terminals of the pair of connection points, and between the one measurement current supply point and the impedance element connected to any one of the terminals.

[0009] Further, in order to achieve the above object, an impedance measurement method according to the present invention includes a measurement target configured to include a plurality of impedance elements connected in series between a pair of terminals, and a non-measurement target connected in parallel via a pair of connection lines connected to a pair of connection points defined on the side of the pair of terminals, the method comprising the steps of: supplying a measurement AC current to the measurement target impedance element via measurement current supply lines connected to one measurement current supply point and the other measurement current supply point defined on the side of any one of the pair of terminals, measuring a supply current value of the measurement AC current supplied to the measurement target impedance element using a first current sensor; measuring a voltage value of a voltage across both ends of the measurement target impedance element; an impedance measurement method for measuring the impedance of the impedance element to be measured based on a voltage value of a voltage, the measurement AC current being supplied to the impedance element to be measured via a pair of measurement current supply lines connected to one measurement current supply point and the other measurement current supply point, which is defined so that the impedance element to be measured is included in a current path between the one measurement current supply point and the other measurement current supply point connected to a connection point of any two of the plurality of impedance elements connected in series, and the other measurement current supply point; and the first current sensor is disposed between a connection point defined on the side of any one of the pair of connection points, the one measurement current supply point, and the impedance element connected to any one of the terminals, to measure a supply current value of the measurement AC current being supplied to the impedance element to be measured.

[0010] In this impedance measuring device and impedance measuring method, a measurement AC current is supplied to the impedance element to be measured via a pair of measurement current supply lines connected to one measurement current supply point and the other measurement current supply point, which are specified so that the impedance element to be measured is included in a current path between one measurement current supply point and the other measurement current supply point, which is connected to a connection point of any two impedance elements connected in series among a plurality of impedance elements, and a first current sensor is disposed at a connection point specified on the side of one of the terminals of the pair of connection points, and between the one measurement current supply point and the impedance element connected to any one of the terminals.

[0011] Therefore, according to this impedance measuring device and impedance measuring method, even when a low-impedance non-measurement object is connected in parallel to a measurement object configured with a plurality of impedance elements, by selecting some of the plurality of impedance elements as the measurement object impedance element, a measurement AC current can be supplied to the measurement object impedance element.As a result, it is possible to measure the supply current value of the measurement AC current flowing only through the measurement object impedance element and the voltage value of the voltage across the measurement object impedance element when the measurement AC current is supplied to the measurement object impedance element, thereby reliably measuring the impedance of the measurement object impedance element.

[0012] In addition, in the impedance measuring device and the impedance measuring method, some of the impedance elements are set as the impedance elements to be measured, and a measurement AC current is supplied to the impedance elements to be measured through a measurement current supply line connected to one measurement current supply point and the other measurement current supply point defined on the side of one of the pair of terminals, respectively, so that one or more impedance elements to be measured with a relatively large impedance are included in the current path through which the measurement AC current flows in the connection line. Therefore, even if the non-measurement object has a low impedance, the impedance of the entire current path becomes large. Therefore, according to the impedance measuring device and the impedance measuring method, the current value of the measurement AC current that is shunted and flows through the non-measurement object can be reduced, and the supply current value of the measurement AC current that is shunted and flows through the measurement object impedance element can be increased accordingly, so that the voltage value of the voltage generated across both ends of the measurement object impedance element can be increased. As a result, with this impedance measuring device and impedance measuring method, the ratio (S / N) of the signal level (S) to the noise level (N) of the voltage across both ends being measured can be sufficiently increased, making it possible to measure the impedance of the impedance element to be measured with sufficiently high accuracy.

[0013] In addition, the impedance measuring device of the present invention measures the impedance of either an electrolysis device or an electrolysis reduction device having a plurality of impedance elements as the measurement target, and measures the impedance by using some of the plurality of impedance elements as the measurement target impedance elements.

[0014] In addition, the impedance measurement method of the present invention measures the impedance of either an electrolysis device or an electrolysis reduction device having a plurality of impedance elements as the measurement target, and measures the impedance by using some of the plurality of impedance elements as the measurement target impedance elements.

[0015] In this impedance measuring device and impedance measuring method, a power supply device having a plurality of impedance elements is treated as a non-measurement object, and either an electrolytic device or an electrolytic reduction device is treated as a measurement object, and impedance is measured using some of the plurality of impedance elements as measurement object impedance elements. This makes it possible to reliably measure the impedance of the measurement object impedance element when a power supply device with an extremely small output impedance is connected in parallel with the measurement object.

[0016] In addition, the impedance measuring device of the present invention includes a first switch that switches between a first switching state in which any one of the terminals is one of the pair of terminals and a second switching state in which any one of the terminals is the other of the pair of terminals, and a second switch that switches the impedance element to be measured that is connected to the voltage measuring unit, and the processing unit controls the switching of the first switch and the second switch.

[0017] According to this impedance measuring device, the processing unit controls the switching of the first switch and the second switch, thereby automatically switching the connection between the voltage measuring unit and the impedance elements to be measured, which are divided into two groups, without manually connecting the voltage measuring unit to the impedance elements to be measured.

[0018] In addition, in the impedance measuring device of the present invention, the processing unit calculates the impedance of some of the impedance elements as the impedance elements to be measured in the first switching state, and calculates the impedance of all of the impedance elements other than the some of the impedance elements as the impedance elements to be measured in the second switching state, and calculates the impedance of the impedance elements to be measured as the sum of the impedance of all of the impedance elements to be measured calculated in the first switching state and the impedance of all of the impedance elements to be measured calculated in the second switching state as the impedance of the object to be measured.

[0019] According to this impedance measuring device, the processing unit calculates the sum of the impedance of the impedance element to be measured calculated in the first switching state and the impedance of the impedance element to be measured calculated in the second switching state as the impedance of the object to be measured, thereby making it possible to calculate the impedance of the object to be measured (i.e., all of the impedance elements to be measured) by performing only two impedance measurements.

[0020] In addition, in the impedance measuring device of the present invention, the first current sensor is arranged on the one terminal side, and includes a second current sensor arranged on the other terminal side and measuring a supply current value of the measurement AC current supplied to the impedance element to be measured, and a third switch that switches between the supply current value measured by the first current sensor and the supply current value measured by the second current sensor and outputs the supply current value measured by the second current sensor to the processing unit, and the second current sensor is arranged between a connection point defined on the other terminal side of the pair of connection points, and one of the measurement current supply points in the second switching state and the impedance element connected to the other terminal, and the processing unit inputs the supply current value measured by the first current sensor in the first switching state and inputs the supply current value measured by the second current sensor in the second switching state by switching and controlling the third switch.

[0021] In this impedance measuring device, the processing unit controls the switching of the third switch to input the supply current value measured by the first current sensor when the first switch is switched to the first switching state, and inputs the supply current value measured by the second current sensor when the first switch is switched to the second switching state.

[0022] Therefore, according to this impedance measuring device, by using two current sensors, the processing unit can automatically input the supply current value measured by the first current sensor and the supply current value measured by the second current sensor in a short time by controlling the switching of the third switch, without having to remove the first current sensor and use it as the second current sensor.

[0023] In the impedance measuring device according to the present invention, the first current sensor and the second current sensor are configured as clamp-type non-contact current sensors configured to be openable and closable.

[0024] According to this impedance measuring device, the first current sensor and the second current sensor are configured as clamp-type non-contact current sensors that can be opened and closed, so that the first current sensor and the second current sensor can be attached to any position on the object to be measured.

[0025] Moreover, the impedance measuring method according to the present invention uses a clamp-type non-contact current sensor that is configured to be openable and closable as the first current sensor.

[0026] According to this impedance measuring method, by using a clamp-type non-contact current sensor that is configured to be openable and closable, the first current sensor can be attached to an arbitrary position on the object to be measured.

[0027] In addition, in the impedance measuring device of the present invention, the measurement current supply unit is configured to be able to vary the frequency of the measurement AC current in accordance with a frequency control signal, and the processing unit outputs the frequency control signal to the measurement current supply unit to vary the frequency of the measurement AC current, thereby acquiring the frequency characteristics of the impedance of the measurement target impedance element at the multiple frequencies.

[0028] Moreover, the impedance measuring method according to the present invention acquires frequency characteristics of the impedance of the measurement target impedance element at a plurality of frequencies.

[0029] According to this impedance measuring device and impedance measuring method, the performance and degradation of the impedance element to be measured can be determined by acquiring the frequency characteristics of the impedance of the impedance element to be measured at a plurality of frequencies.

[0030] In the impedance measuring device according to the present invention, the processing unit acquires the frequency characteristics of the impedance of the measurement target based on the frequency characteristics of the impedance of the measurement target impedance element.

[0031] Moreover, the impedance measuring method according to the present invention acquires the frequency characteristic of the impedance of the measurement object based on the frequency characteristic of the impedance of the measurement object impedance element.

[0032] According to this impedance measuring device and impedance measuring method, the performance or deterioration of the object to be measured can be determined by acquiring the frequency characteristics of the impedance of the object to be measured at a plurality of frequencies.

[0033] In the impedance measuring device according to the present invention, the processing unit obtains, as the frequency characteristic, either a Cole-Cole plot or a Bode plot.

[0034] In the impedance measuring method according to the present invention, either a Cole-Cole plot or a Bode plot is obtained as the frequency characteristic.

[0035] According to this impedance measuring device and impedance measuring method, by acquiring either a Cole-Cole plot or a Bode plot as the frequency characteristic, it is possible to determine with high accuracy the performance or degradation of the impedance element to be measured or the object to be measured. Effect of the Invention

[0036] According to the impedance measuring device and impedance measuring method of the present invention, even when a low-impedance non-measurement object is connected in parallel to a measurement object configured with a plurality of impedance elements, by selecting some of the plurality of impedance elements as the measurement object impedance element, a measurement AC current can be supplied to the measurement object impedance element and the supply current value of the measurement AC current flowing only through the measurement object impedance element can be measured, thereby reliably measuring the impedance of the measurement object impedance element. [Brief description of the drawings]

[0037] [Figure 1] 1 is a diagram showing the configuration of an impedance measuring device 1. FIG. [Diagram 2] 2 is a diagram showing the configuration of a scanner unit 2. FIG. [Diagram 3] 2 is a configuration diagram showing the connections of the components of the impedance measuring device 1 when a control signal Sc is not being output. FIG. [Figure 4] 2 is a configuration diagram showing the connections of the components of the impedance measuring device 1 when a control signal Sc is output. FIG. [Diagram 5] FIG. 1 is an explanatory diagram illustrating a method of using a conventional impedance measuring device 1X. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Hereinafter, an embodiment of an impedance measuring device and an impedance measuring method using the impedance measuring device will be described with reference to the accompanying drawings.

[0039] The impedance measuring device 1 shown in Figure 1 is an example of an impedance device that executes an impedance measuring method, and is configured to be able to measure the impedance of a measurement target impedance element, some or all of the impedance elements being measurement target impedance elements, in a state in which a non-measurement target is connected in parallel to a measurement target configured by connecting a plurality of impedance elements in series via a power supply line Lp as a connection line.

[0040] In this case, the measurement target may be an electrolysis device (electrolysis device) in which a plurality of electrochemical cells (one example of impedance elements) are electrically connected in series to form a stack, an electrolysis reduction device (electrolysis reduction device) in which a plurality of electrolyte membranes (one example of impedance elements) are electrically connected in series to form a stack, a device using an ion exchange membrane in which a plurality of ion exchange membranes (one example of impedance elements) are electrically connected in series to form a stack, a fuel cell in which a plurality of power generation cells (one example of impedance elements) are electrically connected in series to form a stack, and a lithium ion battery or a lead storage battery in which a plurality of battery cells (one example of impedance elements) are electrically connected in series to form a stack. In addition, the non-measurement target may be a power supply device such as an inverter device or a converter device, various loads such as electronic devices, and various power generation devices such as fuel cells in operation or non-operation. Hereinafter, as an example, an example in which an electrolysis device is the measurement target DUT and a power supply device PD that supplies driving power to the measurement target DUT is the non-measurement target will be described.

[0041] First, the measurement target will be described. As shown in FIG. 1, in this example, an electrolysis device in which a plurality of electrochemical cells C1 to C10 (hereinafter, also referred to as "electrochemical cells C" when not distinguished) are electrically connected in series and configured in a stack is used as the measurement target DUT. Note that an electrolysis device is actually configured by connecting several tens to several hundreds of electrochemical cells C in series, but in this example, for ease of understanding, the measurement target DUT is configured by electrically connecting ten electrochemical cells C1 to C10 in series. In this case, the measurement target DUT is provided with a pair of input terminals T1, T11 (an example of a pair of terminals) and terminals T2 to T10 (hereinafter, also referred to as "terminals T" when the terminals T1 to T11 are not distinguished) connected to each connection point of each electrochemical cell C, C.

[0042] Next, a description will be given of the configuration of the impedance measuring device 1. As shown in Fig. 1, the impedance measuring device 1 is configured to include a scanner section 2, a measurement current output section 3, voltage measuring sections 4-1 to 4-5 (hereinafter also referred to as "voltage measuring section 4" when no distinction is made), current sensors 5-1, 5-2 (hereinafter also referred to as "current sensor 5" when no distinction is made), a processing section 6, an output section 7, voltage detection probes P1 to P20 (hereinafter also referred to as "probe P" when no distinction is made), and measurement current supply probes Pi1 to Pi3.

[0043] 2, the scanner unit 2 includes switches S1, S2, S11-S20 (hereinafter, referred to as "switches S" when the switches are not distinguished from one another), and terminals T21-25, T31-T64. In this case, when the control signal Sc is not output from the processor 6 (when the control signal Sc is not output), each switch S maintains a first switching state (a state in which one terminal is the terminal T1 of the pair of terminals T1, T11) in which the fixed contact c and the movable contact a are connected, and when the control signal Sc is output from the processor 6 (when the control signal Sc is output), each switch S maintains a second switching state (a state in which one terminal is the other terminal T11 of the pair of terminals T1, T11) in which the fixed contact c and the movable contact b are connected.

[0044] The switch S1 also functions as a first switch and switches the supply destination of the AC measurement current Im output from the measurement current output unit 3 according to the control signal Sc output from the processing unit 6 via the terminal 64. Specifically, when the control signal Sc is not output, the switch S1 connects a terminal T61 connected to one output unit of the measurement current output unit 3 and connected to the fixed contact c, and a terminal T21 connected to the probe Pi1 and connected to the movable contact a, and when the control signal Sc is output, the switch S1 connects the terminal T61 to a terminal T22 connected to the probe Pi2 and connected to the movable contact b. The terminal 23 and the terminal 62 are connected inside the scanner unit 2, and thus the probe Pi3 (described later) connected to the terminal 23 and the other output unit of the measurement current output unit 3 connected to the terminal 62 are connected.

[0045] Moreover, the switch S2 functions as a third switch, and switches between current value data Di (supply current value) measured by a current sensor 5-1 serving as a first current sensor described later and current value data Di (supply current value) measured by a current sensor 5-2 serving as a second current sensor described later, in accordance with a control signal Sc output from the processing unit 6, and outputs the switched current value data Di (supply current value) to the processing unit 6. Specifically, when the control signal Sc is not being output, the switch S2 connects a terminal T63 connected to the processing unit 6 and connected to the fixed contact c, and a terminal T24 connected to the current sensor 5-1 and connected to the movable contact a, and when the control signal Sc is output, the switch S2 connects the terminal T63 to a terminal T25 connected to the current sensor 5-2 and connected to the movable contact b.

[0046] Furthermore, the switches S11 to S20 function as second switches and switch the electrochemical cell C as the measurement target cell connected to the voltage measurement unit 4 according to the control signal Sc output from the processing unit 6. Specifically, the switches S11 and S12 have a function of connecting either the electrochemical cell C1 or the electrochemical cell C10 to the voltage measurement unit 4-1. In this case, when the control signal Sc is not output, the switch S11 connects a terminal T51, which is connected to one input unit of the voltage measurement unit 4-1 and connected to the fixed contact c of the switch S11, to a terminal T31, which is connected to the terminal T1 of the measurement target DUT and connected to the movable contact a, and when the control signal Sc is output, the switch S11 connects the terminal T51 to a terminal T50, which is connected to the terminal T11 of the measurement target DUT and connected to the movable contact b. In addition, when the control signal Sc is not being output, the switch S12 connects a terminal T52, which is connected to the other input section of the voltage measurement section 4-1 and is connected to the fixed contact c of the switch S12, to a terminal T32, which is connected to the terminal T2 of the DUT to be measured and is connected to the movable contact a, and when the control signal Sc is being output, the switch S12 connects the terminal T52 to a terminal T49, which is connected to the terminal T10 of the DUT to be measured and is connected to the movable contact b.

[0047] The switches S13 and S14 have a function of connecting either the electrochemical cell C2 or the electrochemical cell C9 to the voltage measurement unit 4-2. In this case, when the control signal Sc is not output, the switch S13 connects a terminal T53, which is connected to one input of the voltage measurement unit 4-2 and connected to the fixed contact c of the switch S13, to a terminal T33, which is connected to the terminal T2 of the DUT under test and connected to the movable contact a, and when the control signal Sc is output, the switch S13 connects the terminal T53 to a terminal T48, which is connected to the terminal T10 of the DUT under test and connected to the movable contact b. When the control signal Sc is not output, the switch S14 connects a terminal T54, which is connected to the other input of the voltage measurement unit 4-2 and connected to the fixed contact c of the switch S14, to a terminal T34, which is connected to the terminal T3 of the DUT under test and connected to the movable contact a, and when the control signal Sc is output, the switch S14 connects the terminal T54 to a terminal T47, which is connected to the terminal T9 of the DUT under test and connected to the movable contact b.

[0048] The switches S15 and S16 have a function of connecting either the electrochemical cell C3 or the electrochemical cell C8 to the voltage measurement unit 4-3. In this case, when the control signal Sc is not output, the switch S15 connects a terminal T55, which is connected to one input of the voltage measurement unit 4-3 and connected to the fixed contact c of the switch S15, to a terminal T3 of the DUT to be measured and connected to the movable contact a, and when the control signal Sc is output, the switch S15 connects the terminal T55 to a terminal T9 of the DUT to be measured and connected to the movable contact b. When the control signal Sc is not output, the switch S16 connects a terminal T56, which is connected to the other input of the voltage measurement unit 4-3 and connected to the fixed contact c of the switch S16, to a terminal T36, which is connected to the terminal T4 of the DUT to be measured and connected to the movable contact a, and when the control signal Sc is output, the switch S16 connects the terminal T56 to a terminal T45, which is connected to the terminal T8 of the DUT to be measured and connected to the movable contact b.

[0049] The switches S17 and S18 have a function of connecting either the electrochemical cell C4 or the electrochemical cell C7 to the voltage measurement unit 4-4. In this case, when the control signal Sc is not output, the switch S17 connects a terminal T57, which is connected to one input of the voltage measurement unit 4-4 and connected to the fixed contact c of the switch S17, to a terminal T37, which is connected to the terminal T4 of the DUT under test and connected to the movable contact a, and when the control signal Sc is output, the switch S17 connects the terminal T57 to a terminal T44, which is connected to the terminal T8 of the DUT under test and connected to the movable contact b. When the control signal Sc is not output, the switch S18 connects a terminal T58, which is connected to the other input of the voltage measurement unit 4-4 and connected to the fixed contact c of the switch S18, to a terminal T38, which is connected to the terminal T5 of the DUT under test and connected to the movable contact a, and when the control signal Sc is output, the switch S18 connects the terminal T58 to a terminal T43, which is connected to the terminal T7 of the DUT under test and connected to the movable contact b.

[0050] The switches S19 and S20 have a function of connecting either the electrochemical cell C5 or the electrochemical cell C6 to the voltage measurement unit 4-5. In this case, when the control signal Sc is not output, the switch S19 connects a terminal T59, which is connected to one input of the voltage measurement unit 4-5 and connected to the fixed contact c of the switch S19, to a terminal T39, which is connected to the terminal T5 of the DUT to be measured and connected to the movable contact a, and when the control signal Sc is output, the switch S19 connects the terminal T59 to a terminal T42, which is connected to the terminal T7 of the DUT to be measured and connected to the movable contact b. When the control signal Sc is not output, the switch S20 connects a terminal T60, which is connected to the other input of the voltage measurement unit 4-5 and connected to the fixed contact c of the switch S20, to a terminal T40, which is connected to the terminal T6 of the DUT to be measured and connected to the movable contact a, and when the control signal Sc is output, the switch S20 connects the terminal T60 to a terminal T41, which is connected to the terminal T6 of the DUT to be measured and connected to the movable contact b.

[0051] The measurement current output unit 3 functions as a measurement current supply unit that supplies a measurement AC current to the measurement target cell, 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, according to an instruction from the processing unit 6. In addition, a measurement current supply line Li is connected to one output unit and the other output unit of the measurement current output unit 3. Therefore, as shown in FIG. 3, when the control signal Sc is not output, the measurement current output unit 3 outputs the measurement AC current Im to the electrochemical cells C1 to C5 as the measurement target cells via the measurement current supply lines Li, Li and the probes Pi1, Pi3. In addition, as shown in FIG. 4, when the control signal Sc is output, the measurement current output unit 3 outputs the measurement AC current Im to the electrochemical cells C10 to C6 as the measurement target cells via the measurement current supply lines Li, Li and the probes Pi2, Pi3. The measurement current output section 3 is configured to be able to vary the frequency of the measurement AC current Im, and sweeps (varies) the frequency of the measurement AC current Im in accordance with a frequency control signal Sf output from the processing section 6 and outputs the frequency.

[0052] 3, the voltage measurement unit 4-1, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P1 and P2 (voltage V1 across both ends of the electrochemical cell C1 as the cell to be measured) when the control signal Sc is not being output, and outputs voltage value data Dv1 indicating the measured value (voltage value of the voltage across both ends) to the processing unit 6. Also, as shown in FIG. 4, the voltage measurement unit 4-1, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P20 and P19 (voltage V1 across both ends of the electrochemical cell C10 as the cell to be measured) when the control signal Sc is being output, and outputs voltage value data Dv1 indicating the measured value to the processing unit 6.

[0053] 3, the voltage measurement unit 4-2, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P3 and P4 (voltage V2 across both ends of the electrochemical cell C2 as the cell to be measured) when the control signal Sc is not being output, and outputs voltage value data Dv2 indicating the measured value (voltage value of the voltage across both ends) to the processing unit 6. Also, as shown in FIG. 4, the voltage measurement unit 4-2, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P18 and P17 (voltage V2 across both ends of the electrochemical cell C9 as the cell to be measured) when the control signal Sc is being output, and outputs voltage value data Dv2 indicating the measured value to the processing unit 6.

[0054] 3, the voltage measurement unit 4-3, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P5 and P6 (voltage V3 across both ends of the electrochemical cell C3 as the cell to be measured) when the control signal Sc is not being output, and outputs voltage value data Dv3 indicating the measured value (voltage value of the voltage across both ends) to the processing unit 6. Also, as shown in FIG. 4, the voltage measurement unit 4-3, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P16 and P15 (voltage V3 across both ends of the electrochemical cell C8 as the cell to be measured) when the control signal Sc is being output, and outputs voltage value data Dv3 indicating the measured value to the processing unit 6.

[0055] 3, the voltage measurement unit 4-4, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P7 and P8 (voltage V4 across both ends of the electrochemical cell C4 as the cell to be measured) when the control signal Sc is not being output, and outputs voltage value data Dv4 indicating the measured value (voltage value of the voltage across both ends) to the processing unit 6. Also, as shown in FIG. 4, the voltage measurement unit 4-4, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P14 and P13 (voltage V4 across both ends of the electrochemical cell C7 as the cell to be measured) when the control signal Sc is being output, and outputs voltage value data Dv4 indicating the measured value to the processing unit 6.

[0056] As shown in FIG. 3, the voltage measurement unit 4-5, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P9 and P10 (voltage V5 across both ends of the electrochemical cell C5 as the cell to be measured) when the control signal Sc is not being output, and outputs voltage value data Dv5 indicating the measured value (voltage value of the voltage across both ends) to the processing unit 6. Also, as shown in FIG. 4, the voltage measurement unit 4-5, in accordance with an instruction from the processing unit 6, measures the voltage generated between the probes P12 and P11 (voltage V5 across both ends of the electrochemical cell C6 as the cell to be measured) when the control signal Sc is output, and outputs voltage value data Dv5 indicating the measured value to the processing unit 6. Note that, hereinafter, when the voltages V1 to V5 are not differentiated, they are also referred to as "voltage V across both ends," and when the voltage value data Dv1 to Dv5 are not differentiated, they are also referred to as "voltage value data Dv."

[0057] The current sensors 5-1 and 5-2 can be, for example, a current sensor as disclosed in Japanese Patent Application Laid-Open No. 2014-235045, and are configured as clamp-type ammeters capable of clamping conductors such as coated metal conductors in a non-contact manner. Specifically, the current sensor 5 is configured to include two semicircular magnetic cores 5a and 5b, and a magnetic detection element 5c, for example, configured as a Hall element or a fluxgate element, and functions as a clamp-type non-contact current sensor configured to be able to clamp (insert) the conductor by operating an operation unit not shown in the figure to bring the magnetic cores 5a and 5b close to each other to form an annular opening 5d, and to release (open and close) the clamped conductor by operating the operation unit to move the magnetic cores 5a and 5b away from each other. In addition, in this current sensor 5, the magnetic detection element 5c detects the magnetic flux generated in the magnetic cores 5a and 5b by the current flowing through the conductor inserted in the opening 5d, thereby measuring (detecting) the current value of the current flowing through the conductor in a frequency band from DC to high frequency, and outputs current value data Di indicating the measured current value. However, as the current sensor 5, a sensor capable of measuring the current value of high frequency signals other than DC can be used, and instead of a clamp-type current sensor, a current sensor configured to be non-openable and non-closable using an annular core can also be used.

[0058] The processing unit 6 is configured by, for example, a CPU, and performs overall control of the impedance measuring device 1. Specifically, during impedance measurement, the processing unit 6 controls the measurement current output unit 3 to generate and output a measurement AC current Im. Furthermore, as described below, during impedance measurement, the processing unit 6 measures (calculates) the impedance of each of the electrochemical cells C1 to C5 as measurement target cells when the control signal Sc is not output, and measures (calculates) the impedance of each of the electrochemical cells C1 to C5 as measurement target cells when the control signal Sc is output.

[0059] Specifically, the processing unit 6 controls the current sensor 5 to measure the current flowing through the conductor (terminals T1, T11 in this example) inserted into the opening 5d of the current sensor 5 and output the current value data Di, and controls each voltage measurement unit 4 to measure the voltage between the probes P and output the voltage value data Dv. The processing unit 6 also inputs the current value data Di output from the current sensor 5 and the voltage value data Dv output from the voltage measurement unit 4. The processing unit 6 also measures (calculates) the impedance of the measurement target cell based on the input current value data Di and voltage value data Dv. Specifically, the processing unit 6 calculates the current value (I: supply current value) of the measurement AC current Im flowing through the measurement target cell based on the amplitude of the AC current included in the current value data Di, and calculates the AC voltage at both ends of each measurement target cell (voltage at both ends) as a voltage value (V) based on the amplitude of the AC voltage included in the voltage value data Dv. The processing unit 6 also calculates the phase difference (θ) between the AC current and the AC voltage, i.e., the phase difference (θ) between the AC current flowing through the cell to be measured and the AC voltage generated across the cell to be measured, based on the current value data Di and the voltage value data Dv. The processing unit 6 also measures (calculates) the impedance (impedance Z=V / I, R=Z cosθ, X=Z sinθ) of the cell to be measured, based on the current value (I) of the measurement AC current Im, the voltage value (V) of the AC voltage, and the phase difference (θ) calculated in this way.

[0060] The processing unit 6 also calculates the impedance of the measurement target cells by taking some of the cells as the measurement target cells in the first switching state, and calculates the impedance of all the other cells except some of the cells as the measurement target cells in the second switching state, and calculates the sum of the impedance of all the measurement target cells calculated in the first switching state and the impedance of all the measurement target cells calculated in the second switching state as the impedance of the measurement target DUT (i.e., all the measurement target cells). Specifically, the processing unit 6 calculates the sum of the impedance of each of the electrochemical cells C1 to C5 (some of the cells) measured when the control signal Sc is not output (first switching state) and the impedance of each of the electrochemical cells C10 to C6 (all the other cells except some of the cells) measured when the control signal Sc is output (second switching state) as the impedance of the measurement target DUT as a whole (the impedance between the terminals T1 to T11).

[0061] Moreover, the processing unit 6 outputs a frequency control signal Sf to the measurement current output unit 3 in accordance with an instruction from an operation unit (not shown) to sweep the frequency of the measurement AC current Im between the low frequency band and the high frequency band. The processing unit 6 also outputs display data Dd to the output unit 7 for displaying the measured impedance of the measurement target cell, the impedance of the measurement target DUT as a whole, and frequency characteristics of impedance such as a Cole-Cole plot and Bode diagram (to be described later).

[0062] The output unit 7 is, for example, configured with a display device such as a liquid crystal panel or an organic EL panel, and receives the display data Dd output from the processing unit 6 to display on a screen the impedance of the cell under test, the impedance of the entire DUT under test, and the frequency characteristic of the impedance. Note that instead of a display device, the output unit 7 may be configured with an interface device that performs data communication with an external device, and may output impedance data indicating the impedance of the cell under test, the impedance of the entire DUT under test, and the frequency characteristic of the impedance to this external device.

[0063] The probes Pi1, Pi2, and Pi3 are configured as contact-type probes whose tips are connected (contacted) to the terminals T of the DUT to be measured, respectively, for supplying the AC current Im to be measured. In this case, the probes Pi1, Pi2, and Pi3 are connected to the terminals T21, T22, and T23 of the scanner unit 2, respectively. The probes P1 to P20 are configured as contact-type probes whose tips are connected (contacted) to the terminals T of the DUT to be measured, respectively, for measuring the AC voltage as the voltage across the terminals T, T when the AC current Im to be measured is supplied to the cell to be measured. In this case, the probes P1 to P20 are connected to the terminals T31 to T50 of the scanner unit 2, respectively.

[0064] Next, an impedance measuring method for measuring the impedance of each of the electrochemical cells C1 to C10 and the impedance of the entire DUT under measurement using the impedance measuring device 1 will be described with reference to the drawings.

[0065] First, a method of measuring the impedance of a part (in this example, five of the ten electrochemical cells C) of the ten electrochemical cells C1 to C10 in the DUT to be measured is described. The power supply device PD is connected to a pair of connection points defined on the side of the pair of terminals through a connection line. In this example, the power supply device PD is connected to a pair of connection points Pc1, Pc2 defined on the pair of terminals T1, T11 themselves through a power line Lp as a connection line. In this case, a conductor or the like may be connected to the pair of terminals T1, T11 on the side of the pair of terminals and extended, and a pair of connection points may be defined on the extended conductor or the like.

[0066] Next, the probes Pi1, Pi2, and Pi3 are connected. In this case, the probe Pi1 is connected to one measurement current supply point defined on the side of any one of the pair of terminals, and the probe Pi3 is connected to the other measurement current supply point. In this example, the probe Pi1 is connected to one measurement current supply point Ps1 defined on the terminal T1 (one example of the side of any one of the pair of terminals (one terminal)). The probe Pi2 is connected to one measurement current supply point Ps2 defined on the terminal T11 (one example of the side of any one of the pair of terminals (the other terminal)). The probe Pi3 is connected to a terminal T6 (one example of the other measurement current supply point) connected to the connection point of the electrochemical cells C5 and C6 connected in series. In this case, the terminal T6 functions as the other measurement current supply point Ps3. As with the connection points Pc1 and Pc2, conductors or the like may be connected to the pair of terminals T1, T6, and T11 on the side of the pair of terminals and extended, and measurement current supply points may be defined on the extended conductors or the like.

[0067] Next, probe P1 is connected to terminal T1 of the DUT to be measured, probes P2 and P3 are connected to terminal T2, probes P4 and P5 are connected to terminal T3, probes P6 and P7 are connected to terminal T4, probes P8 and P9 are connected to terminal T5, probes P10 and P11 are connected to terminal T6, probes P12 and P13 are connected to terminal T7, probes P14 and P15 are connected to terminal T8, probes P16 and P17 are connected to terminal T9, probes P18 and P19 are connected to terminal T10, and probe P20 is connected to terminal T11.

[0068] Next, a current sensor 5-1 is placed at a position between a connection point Pc1 defined on the side of one of the pair of connection points PC1 and PC2 (terminal T1 in this example), a measurement current supply point Ps1 functioning as one of the measurement current supply points in the first switching state, and an electrochemical cell C1 connected to the terminal T1 as one of the terminals (terminal T1 is clamped by the current sensor 5-1). Also, a current sensor 5-2 is placed at a position between a connection point Pc2 defined on the side of the other terminal (terminal T11 in this example) of the pair of connection points Pc1 and Pc2, a measurement current supply point Ps2 functioning as one of the measurement current supply points in the second switching state, and an electrochemical cell C10 connected to a terminal T11 (an example of the other terminal) functioning as one of the terminals in the second switching state (terminal T11 is clamped by the current sensor 5-2).

[0069] In this connection state, first, five electrochemical cells C1 to C5 in the DUT to be measured are set as measurement target cells, and the impedance between both ends of each of the electrochemical cells C1 to C5 is measured. At this time, a measurement start switch not shown is operated. As a result, the processing unit 6 outputs a frequency control signal Sf to control the measurement current output unit 3 to output the measurement AC current Im, and stops outputting the control signal Sc. In this state, the scanner unit 2 is in the first switching state, so that each of the switches S1, S2, S11 to S20 connects the fixed contact c and the movable contact a. Therefore, as shown in FIG. 3, a pair of input parts of the voltage measurement unit 4-1 is connected to both ends of the electrochemical cell C1, a pair of input parts of the voltage measurement unit 4-2 is connected to both ends of the electrochemical cell C2, a pair of input parts of the voltage measurement unit 4-3 is connected to both ends of the electrochemical cell C3, a pair of input parts of the voltage measurement unit 4-4 is connected to both ends of the electrochemical cell C4, and a pair of input parts of the voltage measurement unit 4-5 is connected to both ends of the electrochemical cell C5.

[0070] Moreover, the measurement AC current Im output from the measurement current output section 3 is supplied between the measurement current supply point Ps1 and a terminal T6 of the DUT under test. In this state, the measurement AC current Im is branched into a current of a current value I1 flowing through a current path IR1 consisting of one output part of the measurement current output part 3, the measurement current supply line Li, inside the scanner part 2, probe Pi1, the measurement current supply point Ps1, terminal T1, electrochemical cells C1 to C5, terminal T6 of the DUT to be measured, probe Pi3, inside the scanner part 2, the measurement current supply line Li, and the other output part of the measurement current output part 3, and a current of a current value I2 flowing through a current path IR2 consisting of one output part of the measurement current output part 3, the measurement current supply line Li, inside the scanner part 2, probe Pi1, the measurement current supply point Ps1, terminal T1, connection point Pc1, power line Lp, power supply device PD, power line Lp, connection point Pc2, terminal T11, electrochemical cells C10 to C6, terminal T6 of the DUT to be measured, probe Pi3, inside the scanner part 2, the measurement current supply line Li, and the other output part of the measurement current output part 3. A direct current output from the power supply device PD flows through the electrochemical cells C1 to C10 in the DUT under test via the connection points Pc1 and Pc2. That is, the power supply line Lp is an active line through which a direct current flows.

[0071] In this case, the impedance of the power supply device PD is extremely small, but the impedance of the five electrochemical cells C10 to C6 is relatively large. Therefore, the measurement AC current Im that is divided and flows through the current path IR2 including the power supply device PD includes the five electrochemical cells C10 to C6 connected in series in the current path IR2, so the current value I2 is sufficiently small compared to the large current value that flows in a short-circuit state that does not include the electrochemical cells C10 to C6. On the other hand, the current value I1 of the measurement AC current Im that is divided and flows through the five electrochemical cells C1 to C5 is approximately the same as the current value I2. In other words, the current value I2 of the measurement AC current Im that is divided into the power supply device PD becomes smaller, and the current value I1 of the measurement AC current Im that is divided into the electrochemical cells C1 to C5 becomes larger accordingly. As a result, the voltage value V of each of the voltages V generated at both ends of the electrochemical cells C1 to C5 becomes larger. This increases the ratio (S / N) of the signal level (S) of the measurement AC current Im to the noise level (N) of the voltage V measured by each voltage measurement unit 4, so that the impedance can be measured with high accuracy in the impedance calculation process performed by the processing unit 6, which will be described later. At this time, the current sensor 5-1 measures the current value of the current flowing through the terminal T1 inserted (clamped) into the opening 5d. In this case, the current sensor 5-1 measures the current value of the DC current output from the power supply device PD and flowing through the measurement target DUT, and the current value I1 of the measurement AC current Im flowing through the electrochemical cells C1 to C5, and outputs the current value data Di to the processing unit 6.

[0072] In addition, the voltage measurement unit 4-1 measures the voltage V1 (voltage across both ends) at both ends of the electrochemical cell C1 and outputs voltage value data Dv1 to the processing unit 6, the voltage measurement unit 4-2 measures the voltage V2 (voltage across both ends) at both ends of the electrochemical cell C2 and outputs voltage value data Dv2 to the processing unit 6, the voltage measurement unit 4-3 measures the voltage V3 (voltage across both ends) at both ends of the electrochemical cell C3 and outputs voltage value data Dv3 to the processing unit 6, the voltage measurement unit 4-4 measures the voltage V4 (voltage across both ends) at both ends of the electrochemical cell C4 and outputs voltage value data Dv4 to the processing unit 6, and the voltage measurement unit 4-5 measures the voltage V5 (voltage across both ends) at both ends of the electrochemical cell C5 and outputs voltage value data Dv5 to the processing unit 6.

[0073] Next, the processing unit 6 inputs the current value data Di output from the current sensor 5-1 and the voltage value data Dv output from each voltage measurement unit 4. The processing unit 6 also measures (calculates) the impedances of the measurement target cells C1 to C5 based on the input current value data Di and voltage value data Dv.

[0074] Specifically, first, the processing unit 6 corrects the current value indicated by the current value data Di by subtracting the current value of the DC current from data indicating the current values ​​included in the current value data Di (the current value of the DC current and the current value I1 of the measurement AC current Im). As a result, the current value indicated by the corrected current value data Di becomes the current value I (supply current value) of the measurement AC current Im flowing only through the electrochemical cells C1 to C5. Note that when no DC current flows through the measurement target DUT and when the current sensor 5-1 is a current sensor that does not detect DC current, the current value indicated by the current value data Di becomes only the current value I1 of the measurement AC current Im, and therefore the process of subtracting the current value of the DC current from the current value data Di to correct the current value indicated by the current value data Di is not necessary.

[0075] The processing unit 6 also calculates the current value (I) of the measurement AC current Im flowing through the electrochemical cells C1-C5 based on the amplitude of the measurement AC current Im included in the corrected current value data Di, and calculates the AC voltages across each of the electrochemical cells C1-C5 as voltage values ​​(V) based on the amplitude of the AC voltages included in the voltage value data Dv1-Dv5. The processing unit 6 also calculates the phase difference (θ) between the AC current and the AC voltage, i.e., the phase difference (θ) between the AC current (measurement AC current Im) flowing through the electrochemical cells C1-C5 that are the measurement target cells, and each of the AC voltages generated across each of the electrochemical cells C1-C5 that are the measurement target cells, based on the corrected current value data Di and voltage value data Dv. In addition, the processing unit 6 measures (calculates) the impedance (impedance Z=V / I, R=Z·cosθ, X=Z·sinθ) of each of the electrochemical cells C1 to C5, which are the measurement target cells, based on the current value (I), voltage value (V), and phase difference (θ) calculated in this manner.

[0076] Moreover, the processing unit 6 outputs a frequency control signal Sf to the measurement current output unit 3 to sweep the frequency of the measurement AC current Im. Then, the processing unit 6 measures (calculates) the impedances of the electrochemical cells C1 to C5, which are the cells to be measured, at a plurality of frequencies as described above. Next, the processing unit 6 acquires the frequency characteristics of the impedances of the electrochemical cells C1 to C5, which are the cells to be measured, at a plurality of frequencies. In this case, the processing unit 6 acquires, as the frequency characteristics, a Cole-Cole plot showing the impedance characteristics of the electrochemical cell C with respect to frequency, and a Bode diagram showing the gain characteristics and phase characteristics with respect to frequency, etc. Thereafter, the processing unit 6 outputs the display data Dd to the output unit 7 to display the measured impedances of the electrochemical cells C1 to C5, and the acquired Cole-Cole plot and Bode diagram on the display device of the output unit 7. With the above, the processing unit 6 ends the measurement process of the impedances of the electrochemical cells C1 to C5, which are the cells to be measured.

[0077] Next, a measurement method for measuring the impedance of each of the electrochemical cells C10 to C6, except for the electrochemical cells C1 to C5, will be described. Note that, hereinafter, with regard to the above-mentioned processing contents and impedance measurement method by the impedance measuring device 1, duplicated descriptions of the processing contents and measurement methods that are the same as those in the above-mentioned example will be omitted.

[0078] At this time, the processing unit 6 outputs a control signal Sc to the scanner unit 2. In this state, the scanner unit 2 is in the second switching state, and each of the switches S1, S2, S11 to S20 connects the fixed contact c and the movable contact b. Therefore, as shown in FIG. 4, a pair of input parts of the voltage measurement unit 4-1 is connected to both ends of the electrochemical cell C10, a pair of input parts of the voltage measurement unit 4-2 is connected to both ends of the electrochemical cell C9, a pair of input parts of the voltage measurement unit 4-3 is connected to both ends of the electrochemical cell C8, a pair of input parts of the voltage measurement unit 4-4 is connected to both ends of the electrochemical cell C7, and a pair of input parts of the voltage measurement unit 4-5 is connected to both ends of the electrochemical cell C6.

[0079] Moreover, the measurement AC current Im output from the measurement current output section 3 is supplied between the measurement current supply point Ps2 and a terminal T6 of the DUT under test. In this state, the measurement AC current Im is branched into a current of a current value I3 flowing through a current path IR3 consisting of one output part of the measurement current output part 3, the measurement current supply line Li, the scanner part 2, the probe Pi2, the measurement current supply point Ps2, terminal T11, the electrochemical cells C10 to C6, terminal T6 of the DUT to be measured, the probe Pi3, the scanner part 2, the measurement current supply line Li, and the other output part of the measurement current output part 3, and a current of a current value I4 flowing through a current path IR4 consisting of one output part of the measurement current output part 3, the scanner part 2, the probe Pi2, the measurement current supply point Ps2, terminal T11, connection point Pc2, the power line Lp, the power supply device PD, the power line Lp, connection point Pc1, terminal T1, the electrochemical cells C1 to C5, terminal T6 of the DUT to be measured, the probe Pi3, the scanner part 2, the measurement current supply line Li, and the other output part of the measurement current output part 3. A direct current output from the power supply device PD flows through the electrochemical cells C1 to C10 in the DUT under test via the connection points Pc1 and Pc2. That is, the power supply line Lp is an active line through which a direct current flows.

[0080] In this case, the impedance of the power supply device PD is extremely small, but the impedance of the five electrochemical cells C1 to C5 is relatively large. Therefore, the measurement AC current Im that is divided and flows through the current path IR4 including the power supply device PD includes the five electrochemical cells C1 to C5 connected in series in the current path IR4, so the current value I4 is sufficiently small compared to the large current value that flows in a short-circuit state that does not include the electrochemical cells C1 to C5. On the other hand, the current value I3 of the measurement AC current Im that is divided and flows through the five electrochemical cells C10 to C6 is approximately the same as the current value I4. In other words, the current value I4 of the measurement AC current Im that is divided into the power supply device PD becomes smaller, and the current value I3 of the measurement AC current Im that is divided into the electrochemical cells C10 to C6 becomes larger accordingly. As a result, the voltage value V of each of the voltages V generated at both ends of the electrochemical cells C10 to C6 becomes larger. This increases the ratio (S / N) of the signal level (S) of the measurement AC current Im to the noise level (N) of the voltage V measured by each voltage measurement unit 4, so that the impedance can be measured with high accuracy in the impedance calculation process performed by the processing unit 6, which will be described later. At this time, the current sensor 5-2 measures the current value of the current flowing through the terminal T11 inserted (clamped) into the opening 5d. In this case, the current sensor 5-2 measures the current value of the DC current output from the power supply device PD and flowing through the measurement target DUT, and the current value I3 of the measurement AC current Im flowing through the electrochemical cells C10 to C6, and outputs the current value data Di to the processing unit 6.

[0081] In addition, the voltage measurement unit 4-1 measures the voltage V1 (voltage across both ends) at both ends of the electrochemical cell C10 and outputs voltage value data Dv1 to the processing unit 6, the voltage measurement unit 4-2 measures the voltage V2 (voltage across both ends) at both ends of the electrochemical cell C9 and outputs voltage value data Dv2 to the processing unit 6, the voltage measurement unit 4-3 measures the voltage V3 (voltage across both ends) at both ends of the electrochemical cell C8 and outputs voltage value data Dv3 to the processing unit 6, the voltage measurement unit 4-4 measures the voltage V4 (voltage across both ends) at both ends of the electrochemical cell C7 and outputs voltage value data Dv4 to the processing unit 6, and the voltage measurement unit 4-5 measures the voltage V5 (voltage across both ends) at both ends of the electrochemical cell C6 and outputs voltage value data Dv5 to the processing unit 6.

[0082] Next, the processing unit 6 inputs the current value data Di output from the current sensor 5-2 and the voltage value data Dv output from each voltage measurement unit 4. The processing unit 6 also measures (calculates) the impedances of the measurement target cells C10 to C6 based on the input current value data Di and voltage value data Dv.

[0083] Specifically, first, the processing unit 6 corrects the current value indicated by the current value data Di in the same manner as when the electrochemical cells C1 to C5 are measured as the measurement target cells. As a result, the current value indicated by the corrected current value data Di becomes the current value I3 (supply current value) of the measurement AC current Im flowing only through the electrochemical cells C10 to C6.

[0084] The processing unit 6 also calculates the current value (I) of the measurement AC current Im flowing through the electrochemical cells C10-C6 based on the amplitude of the measurement AC current Im included in the corrected current value data Di, and calculates the AC voltages across each of the electrochemical cells C10-C6 as voltage values ​​(V) based on the amplitudes of the AC voltages included in the voltage value data Dv1-Dv5. The processing unit 6 also calculates the phase difference (θ) between the AC current and the AC voltage, i.e., the phase difference (θ) between the AC current (measurement AC current Im) flowing through the electrochemical cells C10-C6 that are the measurement target cells, and each of the AC voltages generated across each of the electrochemical cells C10-C6 that are the measurement target cells, based on the corrected current value data Di and voltage value data Dv. In addition, based on the current value (I), voltage value (V), and phase difference (θ) calculated in this manner, the processing unit 6 measures (calculates) the impedance (impedance Z=V / I, R=Z·cosθ, X=Z·sinθ) of each of the electrochemical cells C10 to C6, which are the cells to be measured.

[0085] Furthermore, the processing unit 6 sweeps the frequency of the measurement AC current Im in the same manner as when measuring the electrochemical cells C1 to C5 as the measurement target cells, thereby acquiring the impedance frequency characteristics (such as the Cole-Cole plots and Bode diagrams described above) of the electrochemical cells C10 to C6 as the measurement target cells. Thereafter, the processing unit 6 outputs display data Dd to the output unit 7, and causes the display device of the output unit 7 to display the measured impedances of the electrochemical cells C10 to C6 and the acquired Cole-Cole plots and Bode diagrams. This completes the process of measuring the impedances of the electrochemical cells C10 to C6 as the measurement target cells by the processing unit 6.

[0086] Furthermore, the processing unit 6 calculates the sum of the impedances of all the electrochemical cells C1 to C5, which are the cells to be measured, calculated in the first switching state, and the impedances of all the electrochemical cells C10 to C6, which are the cells to be measured, calculated in the second switching state, as the impedance of the DUT to be measured. Next, the processing unit 6 acquires the frequency characteristics of the impedance of the DUT to be measured at each frequency (such as the Cole-Cole plot and Bode diagram described above) based on the frequency characteristics of the impedances of the electrochemical cells C10 to C6, which are the cells to be measured. Thereafter, the processing unit 6 outputs the display data Dd to the output unit 7, and causes the display device of the output unit 7 to display the measured impedance of the DUT to be measured and the acquired Cole-Cole plot and Bode diagram. With the above, the processing unit 6 completes the measurement process of the impedance of the DUT to be measured, which is the measurement target, performed by the processing unit 6.

[0087] In this manner, in the impedance measuring device 1 and the impedance measuring method, a current path (current path IR1 or current path IR3) between one measurement current supply point (connection point Pc1 or Pc2 in this example) and the other measurement current supply point (connection point Pc3 in this example) connected to a connection point (terminal T6 in this example) of any two cells (electrochemical cells C5, C6 in this example) connected in series among the plurality of electrochemical cells C1 to C10 is defined so that the measurement target cell (electrochemical cells C1 to C5 or C10 to C6 in this example) is included in the current path. A measurement AC current Im is supplied to the cell to be measured via a pair of measurement current supply lines Li connected to one measurement current supply point and the other measurement current supply point, respectively, and a first current sensor (in this example, current sensor 5-1) is placed at a connection point (in this example, connection point Pc1) defined on the side of one of the terminals (in this example, terminal T1) of the pair of connection points Pc1, Pc2, and between one of the measurement current supply points (in this example, measurement current supply point Ps1) and the cell (in this example, electrochemical cell C1) connected to one of the terminals (in this example, terminal T1).

[0088] Therefore, according to this impedance measuring device 1 and impedance measuring method, even when a low impedance non-measurement target (in this example, a power supply device PD) is connected in parallel to a measurement target DUT comprising a plurality of electrochemical cells C1 to C10, by selecting some of the plurality of electrochemical cells C1 to C10 (in this example, electrochemical cells C1 to C5) as measurement target cells, a measurement AC current Im can be supplied to the measurement target cells. As a result, it is possible to measure the supply current value (current value data Di) of the measurement AC current Im flowing only through the measurement target cells (in this example, electrochemical cells C1 to C5) and the voltage value of the voltage across the measurement target cells when the measurement AC current Im is supplied to the measurement target cells, and therefore the impedance of the measurement target cells (in this example, electrochemical cells C1 to C5) can be reliably measured.

[0089] In addition, in the impedance measuring device 1 and the impedance measuring method, some of the cells (in this example, the electrochemical cells C1 to C5) among the multiple cells (in this example, the electrochemical cells C1 to C10) are taken as the measurement target cells, and a measurement AC current Im is supplied to the measurement target cells via a measurement current supply line Li connected to one measurement current supply point (in this example, the measurement current supply point Ps1) and the other measurement current supply point (in this example, the measurement current supply point Ps3) defined on the side of one of a pair of terminals (in this example, the terminal T1) (terminals T1 and T11). Therefore, one or more measurement target cells (in this example, five electrochemical cells C10 to C6) having a relatively large impedance are included in the current path IR2 through which the measurement AC current Im flows in the power line Lp. Therefore, even if the power supply device PD has a low impedance, the impedance of the current path IR2 as a whole is large. Therefore, according to the impedance measuring device 1 and the impedance measuring method, the current value of the measurement AC current Im that is shunted and flows through the power supply device PD can be reduced, and the supply current value of the measurement AC current Im that is shunted and flows through the measurement target cells (in this example, the electrochemical cells C1 to C5) can be increased accordingly, and as a result, the voltage value of the voltage across the measurement target cells can be increased. As a result, according to the impedance measuring device 1 and the impedance measuring method, the ratio (S / N) of the signal level (S) to the noise level (N) of the voltage across the measurement target can be sufficiently increased, and the impedance of the measurement target cell can be measured with sufficiently high accuracy.

[0090] Furthermore, according to this impedance measuring device 1 and impedance measuring method, the power supply device PD is treated as a non-measurement object, the electrolytic device is treated as a measurement object DUT, and some of the multiple electrochemical cells C1 to C10 in the electrolytic device (in this example, electrochemical cells C1 to C5 or electrochemical cells C10 to C6) are treated as measurement object cells to measure the impedance, thereby making it possible to reliably measure the impedance of the measurement object cells (in this example, electrochemical cells C1 to C5 or electrochemical cells C10 to C6) when the power supply device PD, which has an extremely small output impedance, is connected in parallel to the measurement object DUT.

[0091] Furthermore, the impedance measuring device 1 includes a switch S1 that switches between a first switching state in which any one of the terminals (in this example, terminal T1 or terminal T11) is one terminal (in this example, terminal T1) of a pair of terminals (in this example, terminal T1 or terminal T11) and a second switching state in which any one of the terminals is the other terminal (in this example, terminal T11) of the pair of terminals, and switches S11 to S20 that switch the measurement target cells (in this example, electrochemical cells C1 to C5 or electrochemical cells C10 to C6) connected to the voltage measurement unit (in this example, voltage measurement units 4-1 to 4-5). A processing unit 6 controls the switching of the switch S1 and the switches S11 to S20, thereby automatically switching the connection between the voltage measurement unit and the measurement target cells divided into two groups, without manually connecting the voltage measurement unit to the measurement target cells.

[0092] Furthermore, according to this impedance measuring device 1, the processing unit 6 calculates the sum of the impedance of the measurement target cells (in this example, electrochemical cells C1 to C5) calculated in the first switching state and the impedance of the measurement target cells (in this example, electrochemical cells C10 to C6) calculated in the second switching state as the impedance of the measurement target DUT, thereby making it possible to calculate the impedance of the measurement target DUT (i.e., all of the measurement target cells) by performing only two impedance measurements.

[0093] In addition, in the impedance measuring device 1, the first current sensor (current sensor 5-1 in this example) is arranged on one terminal side (terminal T1 in this example), and includes a second current sensor (current sensor 5-2 in this example) arranged on the other terminal side (terminal T11 in this example) and measuring a supply current value of the measurement AC current Im supplied to the measurement target cell, and a third switch (switch S2 in this example) that switches between the supply current value (current value data Di in this example) measured by the first current sensor (current sensor 5-1 in this example) and the supply current value (current value data Di in this example) measured by the second current sensor (current sensor 5-2 in this example) and outputs the supply current value to the processing unit 6. The second current sensor (current sensor 5-2 in this example) is arranged on one terminal side (terminal T1 in this example) and measures a supply current value of the measurement AC current Im supplied to the measurement target cell. and a connection point (in this example, connection point Pc2) defined on the other terminal side (terminal T11 in this example) of the second switching state, and between one measurement current supply point (in this example, connection point Pc2) in the second switching state and the cell (in this example, electrochemical cell C10) connected to the other terminal (terminal T11 in this example), and the processing unit 6 inputs the supply current value (in this example, current value data Di) measured by the first current sensor (in this example, current sensor 5-1) when the first switch (in this example, switch S1) is switched to the first switching state, by controlling the switching of the third switch (in this example, switch S2), and inputs the supply current value (in this example, current value data Di) measured by the second current sensor (in this example, current sensor 5-2) when the first switch is switched to the second switching state.

[0094] Therefore, according to this impedance measuring device 1, by using two current sensors 5-1, 5-2, the supply current value measured by the current sensor 5-1 (in this example, current value data Di) and the supply current value measured by the current sensor 5-2 (in this example, current value data Di) can be input automatically in a short time by the processing unit 6 switching control of the switch S2, without removing the current sensor 5-1 and using it as the current sensor 5-2.

[0095] Furthermore, according to the impedance measuring device 1 and the impedance measuring method, by using a clamp-type non-contact current sensor that is configured to be openable and closable, the first current sensor can be attached to any position on the DUT under test.

[0096] Furthermore, according to this impedance measuring device 1 and impedance measuring method, the frequency characteristics of the impedance of the measurement target cell (in this example, electrochemical cells C1 to C10) at multiple frequencies can be obtained, thereby making it possible to determine the performance and deterioration of the measurement target cell.

[0097] Furthermore, according to the impedance measuring apparatus 1 and the impedance measuring method, the performance and degradation of the DUT under test can be determined by acquiring the frequency characteristics of the impedance of the DUT under test at a plurality of frequencies.

[0098] Furthermore, according to this impedance measuring device 1 and impedance measuring method, by acquiring either a Cole-Cole plot or a Bode plot as the frequency characteristics, it is possible to determine the performance or degradation of the cell under measurement or the DUT under measurement with high accuracy.

[0099] The present invention is not limited to the above embodiment and can be modified as appropriate. For example, in the above embodiment, five of the ten electrochemical cells C1 to C10 are used as the measurement target cells in one impedance measurement, but the present invention is not limited to this. In one impedance measurement, a part (one to nine) of all the electrochemical cells C1 to C10 can be used as the measurement target cells. In this case, by using half of the electrochemical cells C constituting the measurement target DUT as the measurement target cells in one impedance measurement, the impedance of all the electrochemical cells C can be measured in a short time by performing the impedance measurement only twice.

[0100] In addition, an example has been described in which the voltage V1 across the electrochemical cells C1 and C10 is measured by the voltage measurement unit 4-1, the voltage V2 across the electrochemical cells C2 and C9 is measured by the voltage measurement unit 4-2, the voltage V3 across the electrochemical cells C3 and C8 is measured by the voltage measurement unit 4-3, the voltage V4 across the electrochemical cells C4 and C7 is measured by the voltage measurement unit 4-4, and the voltage V5 across the electrochemical cells C5 and C6 is measured by the voltage measurement unit 4-5. The voltage V1 across electrochemical cells C1 and C6 may be measured by voltage measurement unit 4-1, the voltage V2 across electrochemical cells C2 and C7 may be measured by voltage measurement unit 4-2, the voltage V3 across electrochemical cells C3 and C8 may be measured by voltage measurement unit 4-3, the voltage V4 across electrochemical cells C4 and C9 may be measured by voltage measurement unit 4-4, and the voltage V5 across electrochemical cells C5 and C10 may be measured by voltage measurement unit 4-5.

[0101] Also, although an example using two current sensors 5-1 and 5-2 has been described, it is also possible to use only one current sensor 5-1 without using current sensor 5-2. In this case, since current sensor 5-1 is configured as a clamp-type non-contact current sensor configured to be openable and closable, in the second switching state, current sensor 5-1 can be opened and removed, and clamped at the position of current sensor 5-2, thereby measuring the supply current value of measurement AC current Im in the second switching state.

[0102] Although an example has been described in which the current sensor 5 outputs the current value data Di, it is also possible to adopt a configuration in which the current sensor 5 outputs a current measurement signal that is an analog signal, and the processing unit 6 measures (calculates) the impedance based on the input current measurement signal. Similarly, it is also possible to adopt a configuration in which the voltage measurement unit 4 outputs a voltage measurement signal that is an analog signal, and the processing unit 6 measures (calculates) the impedance based on the input voltage measurement signal.

[0103] In the above embodiment, the first and second current sensors are configured as openable and closable clamp-type non-contact current sensors, but the first and second current sensors can also be configured using shunt resistors. In this case, the supply current value of the measurement AC current Im can be measured by connecting conductors to the terminals T1 and T11 and arranging a shunt resistor in the middle of the conductors.

[0104] In addition, in the above embodiment, an example was described in which switches S1, S2, and S11 to S20 were used. However, in a configuration in which connection switching is performed manually, a configuration in which the switches S1, S2, and S11 to S20 are omitted can also be adopted.

[0105] In addition, although an example of measuring the impedance of each electrochemical cell C has been described, the present invention is not limited to this. For example, when it is necessary to measure only the impedance of the DUT to be measured (all of the electrochemical cells C1 to C10), the impedance of the electrochemical cells C1 to C5 as a whole may be measured by measuring the voltage values ​​of the voltages at both ends of the electrochemical cells C1 to C5 using one voltage measuring unit 4, and the impedance of the electrochemical cells C10 to C6 as a whole may be measured by measuring the voltage values ​​of the voltages at both ends of the electrochemical cells C10 to C6 using the one voltage measuring unit 4, and the sum of the measured impedances may be calculated as the impedance of the DUT to be measured. Furthermore, the impedance of the whole of the electrochemical cells C may be measured by measuring the voltage values ​​of the voltages at both ends of a plurality of the electrochemical cells C among the ten electrochemical cells C using a single voltage measuring unit 4. In addition, in the above embodiment, an example of measuring the impedance of all the electrochemical cells C has been described, but only the impedance of a specific electrochemical cell C may be measured.

[0106] In the above embodiment, the other measurement current supply point (measurement current supply point Ps3 in this example) is defined as the connection point of two electrochemical cells C5 and C6 connected in series so that the measurement target cell (electrochemical cells C1 to C5 or electrochemical cells C10 to C6 in this example) is included in the current path (current path IR1 or current path IR3 in this example) between the other measurement current supply point (measurement current supply point Ps1 or measurement current supply point Ps2 in this example), but this is not limited to this example. As long as the measurement target cell is included in the current path, for example, when the electrochemical cells C1 to C5 are the measurement target cells, the other measurement current supply point (measurement current supply point Ps3) can be defined as the connection point of any of the two electrochemical cells C6 and C7, electrochemical cells C7 and C8, electrochemical cells C8 and C9, and electrochemical cells C9 and C10 connected in series. Similarly, when the electrochemical cells C10 to C6 are the measurement target cells, the other measurement current supply point (measurement current supply point Ps3) can be set to the connection point of any one of the two serially connected electrochemical cells C5, C4, C4, C3, C3, C2, and C2, C1. However, when measuring the impedance of some or all of the electrochemical cells C by two impedance measurements, it is preferable to set the connection point to the connection point of the two electrochemical cells C, C (in this example, the electrochemical cells C5, C6) located on the center side of the measurement target DUT in each impedance measurement, since this eliminates the need to switch the connection of the probe Pi3 to the terminal of the measurement target DUT.

[0107] In the above embodiment, an example was described in which an electrolytic device was used as the DUT to be measured, but an electrolytic reduction device (electrolytic reduction device), a device using an ion exchange membrane, a fuel cell, a lithium ion battery, and a lead acid battery can be used as the DUT to be measured. Note that an organic electrolytic reduction device used in the production of MCH (methylcyclohexane), which is one of the hydrogen carriers, is known as an electrolytic reduction device (see JP 2022-30943 A). [Industrial Applicability]

[0108] According to the present invention, even when a low-impedance non-measurement object is connected in parallel to the measurement object, by selecting some of the impedance elements among the multiple impedance elements as the measurement object impedance element, it is possible to supply the measurement AC current Im to the measurement object impedance element, and as a result, it is possible to measure the current value of the measurement AC current flowing only through the measurement object impedance element and the voltage value of the voltage across the measurement object impedance element, thereby making it possible to reliably measure the impedance of the measurement object impedance element. As a result, the present invention can be widely applied to impedance measurement devices and impedance measurement methods for such impedance measurements. [Explanation of symbols]

[0109] 1. Impedance measuring device 2 Scanner section 3. Measurement current output section 4-1~4-5 Voltage measurement section 5-1, 5-2 Current sensor 6 Processing section C1~C10 Electrochemical cells Di Current value data DUT Measurement target Dv1~Dv5 voltage value data Lc connection line Li measurement current supply line Pc1,Pc2 connection point PD power supply Ps1~Ps3 Measured current supply point

Claims

1. a measurement current supply unit that supplies a measurement AC current to an impedance element to be measured via a measurement current supply line connected to one measurement current supply point and the other measurement current supply point, the measurement current supply line being connected to a pair of measurement current supply points ... a first current sensor that measures a supply current value of the measurement AC current supplied to the measurement target impedance element; a voltage measurement unit for measuring a voltage value of a voltage across both ends of the impedance element to be measured; a processing unit that calculates an impedance of the impedance element to be measured based on the measured supply current value and the voltage value of the voltage across the two ends, the measurement current supply unit supplies the measurement AC current to the impedance element to be measured via the pair of measurement current supply lines connected to the one measurement current supply point and the other measurement current supply point, which are defined so that the impedance element to be measured is included in a current path between the one measurement current supply point and the other measurement current supply point connected to a connection point of any two of the plurality of impedance elements connected in series; The first current sensor is an impedance measuring device that is arranged at a connection point defined on the side of any one of the pair of connection points, and between the one measurement current supply point and the impedance element connected to any one of the terminals.

2. 2. The impedance measuring device according to claim 1, wherein a power supply device is the non-measurement object, and either one of an electrolysis device and an electrolysis reduction device having a plurality of impedance elements is the measurement object, and the impedance is measured by using some of the plurality of impedance elements as the measurement object impedance elements.

3. a first switch that switches between a first switching state in which the one of the terminals is one of the pair of terminals and a second switching state in which the one of the terminals is the other of the pair of terminals; a second switch that switches the impedance element to be measured that is connected to the voltage measurement unit; The impedance measuring device according to claim 1 , wherein the processing unit controls switching of the first switch and the second switch.

4. 4. The impedance measuring device according to claim 3, wherein the processing unit calculates the impedance of a part of the impedance elements as the impedance elements to be measured in the first switching state, and calculates the impedance of the impedance elements to be measured by using all of the impedance elements other than the part of the impedance elements as the impedance elements to be measured in the second switching state, and calculates the sum of the impedance of all of the impedance elements to be measured calculated in the first switching state and the impedance of all of the impedance elements to be measured calculated in the second switching state as the impedance of the object to be measured.

5. the first current sensor is disposed on the one terminal side, a second current sensor that is disposed on the other terminal side and that measures a supply current value of the measurement AC current that is supplied to the measurement target impedance element; a third switch that switches between the supply current value measured by the first current sensor and the supply current value measured by the second current sensor and outputs the supply current value measured by the second current sensor to the processing unit, the second current sensor is disposed at a connection point of the pair of connection points that is defined on the side of the other terminal, and between the one measurement current supply point in the second switching state and the impedance element connected to the other terminal; 4. The impedance measuring device of claim 3, wherein the processing unit inputs the supply current value measured by the first current sensor in the first switching state and inputs the supply current value measured by the second current sensor in the second switching state by switching and controlling the third switch.

6. 6. The impedance measuring device according to claim 5, wherein the first current sensor and the second current sensor are configured as openable and closable clamp-type non-contact current sensors.

7. the measurement current supply unit is configured to vary a frequency of the measurement AC current in accordance with a frequency control signal; 2. The impedance measuring device according to claim 1, wherein the processing unit acquires frequency characteristics of the impedance of the measurement target impedance element at the multiple frequencies by outputting the frequency control signal to the measurement current supply unit to vary the frequency of the measurement AC current.

8. 8. The impedance measuring device according to claim 7, wherein the processing unit acquires the frequency characteristics of the impedance of the measurement target based on the frequency characteristics of the impedance of the measurement target impedance element.

9. 9. The impedance measuring device according to claim 7, wherein the processing unit obtains, as the frequency characteristic, either a Cole-Cole plot or a Bode plot.

10. a measurement target configured to include a plurality of impedance elements connected in series between a pair of terminals, and a non-measurement target connected in parallel via connection lines connected to a pair of connection points defined on the side of the pair of terminals, a measurement AC current is supplied to the measurement target impedance elements via measurement current supply lines respectively connected to one measurement current supply point and the other measurement current supply point defined on the side of any one of the pair of terminals, with some of the plurality of impedance elements being measurement target impedance elements; measuring a supply current value of the measurement AC current supplied to the measurement target impedance element using a first current sensor; Measure a voltage value across both ends of the impedance element to be measured; An impedance measurement method for measuring an impedance of the measurement target impedance element based on the measured supply current value and the measured voltage value of the voltage across the two ends, comprising: supplying the measurement AC current to the impedance element to be measured via the pair of measurement current supply lines connected to the one measurement current supply point and the other measurement current supply point, respectively, defined so that the impedance element to be measured is included in a current path between the one measurement current supply point and the other measurement current supply point connected to a connection point of any two of the plurality of impedance elements connected in series; An impedance measurement method in which the first current sensor is disposed between a connection point defined on the side of any one of the pair of connection points and one of the measurement current supply points and the impedance element connected to any one of the terminals, and the supply current value of the measurement AC current being supplied to the impedance element to be measured is measured.

11. 11. The impedance measurement method according to claim 10, wherein a power supply device is treated as the non-measurement object, and either one of an electrolysis device and an electrolysis-reduction device having a plurality of impedance elements is treated as the measurement object, and the impedance is measured using some of the plurality of impedance elements as the measurement object impedance elements.

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

13. The impedance measuring method according to claim 10, further comprising the step of acquiring frequency characteristics of the impedance of the impedance element to be measured at a plurality of frequencies.

14. The impedance measuring method according to claim 13, wherein the frequency characteristic of the impedance of the measurement object is obtained based on the frequency characteristic of the impedance of the measurement object impedance element.

15. The impedance measuring method according to claim 13 or 14, wherein one of a Cole-Cole plot and a Bode plot is obtained as the frequency characteristic.

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