Impedance measuring device and impedance measuring method

Abstract

The present invention measures the impedance of the impedance elements of a measurement target, which is configured by connecting a plurality of impedance elements in series, while a non-measurement target is connected in parallel to the measurement target.　This impedance measuring device comprises: a measurement current output unit 3 that supplies a measurement AC current Im to some electrochemical cells C1-C5 as measurement target cells while a power source device PD is connected in parallel to a measurement target DUT; a current sensor 5-1 that measures a supplied current value of the measurement AC current Im; and a processing unit 6 that computes the impedance of the measurement target cells on the basis of the supplied current value and a voltage value of a voltage across both ends of the measurement target cells. The measurement current output unit 3 supplies the measurement AC current Im to the measurement target cells via a measurement current supply line Li connected to measurement current supply points Ps1, Ps3 in a manner in which the measurement target cells are included between the measurement current supply point Ps1 and the measurement current supply point Ps3. The current sensor 5-1 is disposed between the electrochemical cell C1 and a connection point Pc1 as well as the measurement current supply point Ps1.

Description

Impedance measuring device and impedance measuring method

[0001] The present invention relates to an impedance measuring device and an impedance measuring method that can measure the impedance of some or all of a plurality of impedance elements when a measurement object configured by connecting a plurality of impedance elements in series is connected in parallel to a non-measurement object via a connection line.

[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 when the measurement object is connected in parallel with the non-measurement object via a connection line. This impedance measuring device is configured to measure the internal impedance of a secondary battery when the non-measurement object is connected in parallel with the secondary battery via a power 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 an arithmetic control unit. In this case, the AC current detection unit is configured to include a clamp-type current sensor.

[0003] When measuring the internal impedance of a secondary battery using this impedance measuring device, first, a power line is inserted through the opening of the 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 portion of the measurement AC current flows through the secondary battery. Meanwhile, the remaining portion of the measurement AC current flows through the load, along with a DC current output from the secondary battery. In this case, the current sensor in the AC current detection unit detects the AC current flowing through the power line passing through the opening and outputs a negative feedback current corresponding to the AC current value. At this time, the flow of the feedback current generates an AC voltage across the detection resistor. Next, the A / D conversion unit A / D converts the detected AC current data into AC current data indicating the AC current value and outputs the data to the calculation control unit. Furthermore, the AC voltage detection unit detects the voltage across the secondary battery and outputs AC voltage data indicating the voltage value of the voltage across the battery 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.

[0004] JP 2004-251625 A (pages 3-8, Figure 1)

[0005] However, the above-described impedance measuring device has the following problems. As conceptually shown in FIG. 5 , the following describes the problems encountered when using the above-described impedance measuring device 1X to measure the impedance of an operating DUT, such as an electrolysis device (electrolysis device) that generates hydrogen and oxygen. In this case, the DUT is connected in parallel to a power supply device PD that supplies DC current to the DUT via a power supply line Lp. Therefore, when measuring the impedance of an operating DUT, the AC current supply unit U1 supplies a measurement AC current Im to the DUT via the measurement current supply line Li and terminals T1 and T11 at both ends of the DUT. In this state, the current sensor U4 measures the current value of the measurement AC current Im flowing through the DUT, and the AC voltage detection unit U2 detects the AC voltage value generated between the terminals T1 and T11 of the DUT. Next, the calculation control unit U3 measures the impedance of the DUT under test 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 essentially short-circuited by the power line Lp. Therefore, even if the AC current supply unit UI outputs a measurement AC current Im, almost all of the measurement AC current Im is shunted to the power supply device PD, and no measurement AC current Im flows through the DUT under test. Therefore, the AC voltage value 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 across both ends of the DUT under test. Therefore, this impedance measurement device 1X has the problem of being unable to 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 its main object is to provide an impedance measuring device and an impedance measuring method that can measure the impedance of some or all of multiple impedance elements in a state where a measurement object configured by connecting multiple impedance elements in series is connected in parallel to a non-measurement object via a connection line.

[0008] In order to achieve the above object, the impedance measuring device according to the present invention includes a measurement object configured to include a plurality of impedance elements connected in series between a pair of terminals, and a non-measurement object connected in parallel via connection lines connected to a pair of connection points defined on the side of the pair of terminals, and the impedance measuring device includes a measurement current supply unit that supplies a measurement AC current to the measurement object 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 one of the pair of terminals, a first current sensor that measures the supply current value of the measurement AC current being supplied to the measurement object impedance element, a voltage measurement unit that measures the voltage value of both ends of the measurement object impedance element, and a voltage measurement unit that measures the voltage value of the voltage across both ends of the measurement object 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 across the two ends, wherein the measurement current supply unit supplies the measurement AC current 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 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 plurality of impedance elements that are connected in series, and the first current sensor is arranged between a connection point defined on the side of one of the pair of connection points, the one measurement current supply point, and the impedance element connected to any one of the terminals.

[0009] Furthermore, in order to achieve the above object, an impedance measurement method according to the present invention includes the steps of: connecting a measurement target configured to include a plurality of impedance elements connected in series between a pair of terminals to 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; 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 being 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 method comprising: supplying the measurement AC current 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, the one measurement current supply point being connected to a connection point of any two of the plurality of impedance elements connected in series, such 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; and measuring a supply current value of the measurement AC current being supplied to the impedance element to be measured by arranging the first current sensor between a connection point defined on the side of one of the pair of connection points, the one measurement current supply point, and the impedance element connected to any one of the terminals.

[0010] In this impedance measuring device and impedance measuring method, an AC current to be measured 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 placed at a connection point specified on the side of one of the terminals of the pair of connection points, and between one measurement current supply point and the impedance element connected to any one of the terminals.

[0011] Therefore, with 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, it is possible to supply a measurement AC current 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 enabling the impedance of the measurement object impedance element to be measured reliably.

[0012] In addition, in this impedance measuring device and impedance measuring method, some of the impedance elements are selected as measurement target impedance elements, and a measurement AC current is supplied to the measurement target impedance elements via a measurement current supply line connected to one measurement current supply point and the other measurement current supply point defined on one of the pair of terminals. Therefore, the current path through which the measurement AC current flows through the connection line includes at least one measurement target impedance element with a relatively large impedance. Therefore, even if the non-measurement target impedance element has a low impedance, the impedance of the entire current path will be large. Therefore, with this impedance measuring device and impedance measuring method, the current value of the measurement AC current shunted to flow through the non-measurement target impedance element can be reduced, and the supply current value of the measurement AC current shunted to flow through the measurement target impedance element can be increased accordingly, resulting in a large voltage value across the measurement target impedance element. 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 the two 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 according to 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 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 not the object of measurement, and either an electrolytic device or an electrolytic reduction device is the object of measurement, and impedance is measured using some of the plurality of impedance elements as the impedance elements to be measured.This makes it possible to reliably measure the impedance of the impedance elements to be measured when a power supply device with an extremely small output impedance is connected in parallel to the object of measurement.

[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 having to manually connect 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 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.

[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 simply performing two impedance measurements.

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

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

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

[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 that are 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] Furthermore, 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 measurement 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 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 impedance element to be measured at the multiple frequencies.

[0028] Furthermore, the impedance measuring method according to the present invention acquires the frequency characteristics of the impedance of the impedance element to be measured 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 object based on the frequency characteristics of the impedance of the measurement object impedance element.

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

[0032] According to this impedance measuring device and impedance measuring method, the frequency characteristics of the impedance of the object to be measured at a plurality of frequencies are obtained, thereby making it possible to determine the performance or degradation of the object to be measured.

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

[0034] In addition, the impedance measuring method according to the present invention acquires either a Cole-Cole plot or a Bode diagram as the frequency characteristics.

[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 characteristics, it is possible to determine with high accuracy the performance and degradation of the impedance element to be measured or the object to be measured.

[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, it is possible to supply a measurement AC current to the measurement object impedance element and measure the supply current value of the measurement AC current flowing only through the measurement object impedance element, thereby enabling the impedance of the measurement object impedance element to be measured reliably.

[0037] FIG. 1 is a configuration diagram showing the configuration of an impedance measuring device 1. FIG. 2 is a configuration diagram showing the configuration of a scanner unit 2. FIG. 3 is a configuration diagram showing the connection relationships of the components of the impedance measuring device 1 when a control signal Sc is not output. FIG. 4 is a configuration diagram showing the connection relationships of the components of the impedance measuring device 1 when a control signal Sc is output. FIG. 5 is an explanatory diagram explaining how to use a conventional impedance measuring device 1X.

[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 performs an impedance measurement method, and is configured to be able to measure the impedance of a measurement target impedance element, some or all of which are measurement target impedance elements, in a state in which a measurement target configured by connecting multiple impedance elements in series and a non-measurement target are connected in parallel 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 multiple electrochemical cells (an example of an impedance element) are electrically connected in series to form a stack; an electrolysis-reduction device (electrolysis-reduction device) in which multiple electrolyte membranes (an example of an impedance element) are electrically connected in series to form a stack; an ion exchange membrane device in which multiple ion exchange membranes (an example of an impedance element) are electrically connected in series to form a stack; a fuel cell in which multiple power generation cells (an example of an impedance element) are electrically connected in series to form a stack; and a lithium ion battery or lead-acid battery in which multiple battery cells (an example of an impedance element) are electrically connected in series to form a stack. Furthermore, 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. Below, as an example, an electrolysis device is used as the measurement target DUT, and a power supply device PD that supplies power to the measurement target DUT is used as the non-measurement target.

[0041] First, the measurement target will be described. As shown in FIG. 1 , in this example, the measurement target DUT is an electrolysis device configured by electrically connecting multiple electrochemical cells C1 to C10 (hereinafter, also referred to as "electrochemical cells C" when not distinguishing between them) in a stacked configuration. While an electrolysis device is actually configured by connecting tens to hundreds of electrochemical cells C in series, in this example, for ease of understanding, the measurement target DUT is configured by electrically connecting 10 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 not distinguishing between the terminals T1 to T11) connected to the connection points of each of the electrochemical cells C, C.

[0042] Next, we will explain the configuration of the impedance measuring device 1. As shown in Figure 1, the impedance measuring device 1 is configured to include a scanner unit 2, a measurement current output unit 3, voltage measurement units 4-1 to 4-5 (hereinafter, also referred to as "voltage measurement unit 4" when not distinguished), current sensors 5-1 and 5-2 (hereinafter, also referred to as "current sensor 5" when not distinguished), a processing unit 6, an output unit 7, voltage detection probes P1 to P20 (hereinafter, also referred to as "probe P" when not distinguished), and measurement current supply probes Pi1 to Pi3.

[0043] 2, the scanner unit 2 is configured to include switches S1, S2, and switches S11 to S20 (hereinafter, referred to as "switch S" when the switches are not to be distinguished from one another), and terminals T21 to T25 and T31 to T64. In this case, when a control signal Sc is not output from the processing unit 6 (when the control signal Sc is not being output), each switch S maintains a first switching state in which the fixed contact c and the movable contact a are connected (a state in which one terminal is set to one terminal T1 of the pair of terminals T1, T11), and when a control signal Sc is output from the processing unit 6 (when the control signal Sc is being output), each switch S maintains a second switching state in which the fixed contact c and the movable contact b are connected (a state in which one terminal is set to the other terminal T11 of the pair of terminals T1, T11).

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

[0045] Furthermore, the switch S2 functions as a third switch, and in accordance with a control signal Sc output from the processing unit 6, 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), and outputs the selected data to the processing unit 6. Specifically, when the control signal Sc is not being output, the switch S2 connects a terminal T63, which is connected to the processing unit 6 and to the fixed contact c, to a terminal T24, which is connected to the current sensor 5-1 and to the movable contact a, and when the control signal Sc is being output, the switch S2 connects the terminal T63 to a terminal T25, which is connected to the current sensor 5-2 and to the movable contact b.

[0046] Furthermore, 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 in accordance with a control signal Sc output from the processing unit 6. Specifically, switches S11 and S12 have the function of connecting either electrochemical cell C1 or electrochemical cell C10 to the voltage measurement unit 4-1. In this case, when the control signal Sc is not being output, switch S11 connects terminal T51, which is connected to one input unit of the voltage measurement unit 4-1 and to fixed contact c of switch S11, to terminal T31, which is connected to terminal T1 of the measurement target DUT and to movable contact a; when the control signal Sc is being output, switch S11 connects terminal T51 to terminal T50, which is connected to terminal T11 of the measurement target DUT and to 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] Switches S13 and S14 also function to connect either electrochemical cell C2 or electrochemical cell C9 to the voltage measurement unit 4-2. In this case, when the control signal Sc is not being output, switch S13 connects terminal T53, which is connected to one input of the voltage measurement unit 4-2 and connected to fixed contact c of switch S13, with terminal T33, which is connected to terminal T2 of the DUT under test and connected to movable contact a. When the control signal Sc is being output, switch S13 connects terminal T53 with terminal T48, which is connected to terminal T10 of the DUT under test and connected to movable contact b. When the control signal Sc is not being output, switch S14 connects terminal T54, which is connected to the other input of the voltage measurement unit 4-2 and connected to fixed contact c of switch S14, with terminal T34, which is connected to terminal T3 of the DUT under test and connected to movable contact a. When the control signal Sc is being output, switch S14 connects terminal T54 with terminal T47, which is connected to terminal T9 of the DUT under test and connected to movable contact b.

[0048] Switches S15 and S16 also function to connect either electrochemical cell C3 or electrochemical cell C8 to the voltage measurement unit 4-3. When the control signal Sc is not being output, switch S15 connects terminal T55, which is connected to one input of the voltage measurement unit 4-3 and to fixed contact c of switch S15, with terminal T35, which is connected to terminal T3 of the DUT under test and to movable contact a. When the control signal Sc is being output, switch S15 connects terminal T55 with terminal T46, which is connected to terminal T9 of the DUT under test and to movable contact b. When the control signal Sc is not being output, switch S16 connects terminal T56, which is connected to the other input of the voltage measurement unit 4-3 and to fixed contact c of switch S16, with terminal T36, which is connected to terminal T4 of the DUT under test and to movable contact a. When the control signal Sc is being output, switch S16 connects terminal T56 with terminal T45, which is connected to terminal T8 of the DUT under test and to movable contact b.

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

[0050] Switches S19 and S20 also function to connect either electrochemical cell C5 or electrochemical cell C6 to the voltage measurement unit 4-5. In this case, when the control signal Sc is not being output, switch S19 connects terminal T59, which is connected to one input of the voltage measurement unit 4-5 and connected to fixed contact c of switch S19, with terminal T39, which is connected to terminal T5 of the DUT under test and connected to movable contact a. When the control signal Sc is being output, switch S19 connects terminal T59 with terminal T42, which is connected to terminal T7 of the DUT under test and connected to movable contact b. When the control signal Sc is not being output, switch S20 connects terminal T60, which is connected to the other input of the voltage measurement unit 4-5 and connected to fixed contact c of switch S20, with terminal T40, which is connected to terminal T6 of the DUT under test and connected to movable contact a. When the control signal Sc is being output, switch S20 connects terminal T60 with terminal T41, which is connected to terminal T6 of the DUT under test and connected to 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. In accordance with instructions from the processing unit 6, the measurement current output unit 3 generates and outputs a measurement AC current Im, which is a sinusoidal AC signal for measuring the impedance of the measurement target cell. Furthermore, a measurement current supply line Li is connected to one output terminal and the other output terminal of the measurement current output unit 3. Therefore, as shown in FIG. 3 , when the control signal Sc is not being output, the measurement current output unit 3 outputs the measurement AC current Im to the electrochemical cells C1 to C5, which are the measurement target cells, via the measurement current supply lines Li, Li and probes Pi1 and Pi3. Furthermore, as shown in FIG. 4 , when the control signal Sc is being output, the measurement current output unit 3 outputs the measurement AC current Im to the electrochemical cells C10 to C6, which are the measurement target cells, via the measurement current supply lines Li, Li and probes Pi2 and Pi3. In addition, the measurement current output unit 3 is configured to be able to change the frequency of the measurement AC current Im, and sweeps (changes) the frequency of the measurement AC current Im and outputs it in accordance with the frequency control signal Sf output from the processing unit 6.

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

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

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

[0055] 3, in accordance with instructions from the processing unit 6, when the control signal Sc is not being output, the voltage measurement unit 4-4 measures the voltage generated between the probes P7 and P8 (the voltage V4 across both ends of the electrochemical cell C4 as the cell to be measured) and outputs voltage value data Dv4 indicating the measured value (the voltage value of the voltage across both ends) to the processing unit 6. Also, as shown in FIG. 4, in accordance with instructions from the processing unit 6, when the control signal Sc is being output, the voltage measurement unit 4-4 measures the voltage generated between the probes P14 and P13 (the voltage V4 across both ends of the electrochemical cell C7 as the cell to be measured) 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 instructions from the processing unit 6, measures the voltage generated between the probes P9 and P10 (the 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 (the 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 instructions from the processing unit 6, measures the voltage generated between the probes P12 and P11 (the voltage V5 across both ends of the electrochemical cell C6 as the cell to be measured) when the control signal Sc is being 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 distinguished, they are also referred to as the "voltage V" and when the voltage value data Dv1 to Dv5 are not distinguished, they are also referred to as the "voltage value data Dv."

[0057] The current sensors 5-1 and 5-2 may be, for example, current sensors such as those disclosed in Japanese Patent Application Laid-Open No. 2014-235045, and are configured as clamp-type ammeters capable of contactlessly clamping conductors such as coated metal conductors. Specifically, the current sensor 5 includes two semicircular magnetic cores 5a and 5b and a magnetic detection element 5c formed, for example, by a Hall element or a fluxgate element. By operating an operating unit (not shown) to bring the magnetic cores 5a and 5b close to each other, an annular opening 5d is formed, through which the conductor can be clamped (inserted). By operating the operating unit to move the magnetic cores 5a and 5b apart from each other, the current sensor 5 can release the clamp on the clamped conductor (open and close). In this current sensor 5, the magnetic detection element 5c detects the magnetic flux generated in the magnetic cores 5a and 5b when a current flows 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 ranging from DC to high frequencies, 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 also be used, and instead of a clamp-type current sensor, a current sensor using an annular core and configured to be unable to be opened or closed can also be used.

[0058] The processing unit 6 is configured, for example, by 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 will be described later, 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 C10 to C6 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 and T11 in this example) inserted into the opening 5d of the current sensor 5 and output the current value data Di, and also controls each voltage measurement unit 4 to measure the voltage between the probes P and P and output the voltage value data Dv. The processing unit 6 also receives 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 across 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 AC voltage, i.e., the phase difference (θ) between the AC current flowing through the cell and the AC voltage occurring across the cell, based on the current value data Di and the voltage value data Dv. The processing unit 6 also measures (calculates) the impedance of the cell (impedance Z=V / I, R=Z·cos θ, X=Z·sin θ) 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] Furthermore, the processing unit 6 calculates the impedances of some of the cells as the measurement target cells in the first switching state, and calculates the impedances of all of the cells except for some of the cells as the measurement target cells in the second switching state, and calculates the sum of the impedances of all of the measurement target cells calculated in the first switching state and the impedances of all of the measurement target cells calculated in the second switching state as the impedance of the measurement target DUT (i.e., all of the measurement target cells). Specifically, the processing unit 6 calculates the sum of the impedances 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 impedances of the electrochemical cells C10 to C6 (all of the cells except for some of the cells) measured when the control signal Sc is output (second switching state) as the impedance of the entire measurement target DUT (the impedance between the terminals T1 to T11).

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

[0062] The output unit 7 is, for example, configured with a display device (display) 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 characteristics 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 characteristics of the impedance to this external device.

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

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

[0065] First, a measurement method will be described in which some of the ten electrochemical cells C1-C10 (in this example, five of the ten electrochemical cells C) in the DUT are used as the measurement target cells, and the impedances of the measurement target cells are measured. The power supply device PD is connected via connection lines to a pair of connection points defined on the side of the pair of terminals. In this example, the power supply device PD is connected via power supply lines Lp as connection lines to a pair of connection points Pc1, Pc2 defined on the pair of terminals T1, T11 themselves. In this case, conductors or the like may be connected to the pair of terminals T1, T11 and extended, and a pair of connection points may be defined on each of the extended conductors or the like.

[0066] Next, probes Pi1, Pi2, and Pi3 are connected. In this case, probe Pi1 is connected to one measurement current supply point defined on the side of one of the pair of terminals, and probe Pi3 is connected to the other measurement current supply point. In this example, probe Pi1 is connected to one measurement current supply point Ps1 defined on terminal T1 (an example of one of the pair of terminals (one terminal) side). Probe Pi2 is connected to one measurement current supply point Ps2 defined on terminal T11 (an example of one of the pair of terminals (the other terminal) side). Probe Pi3 is connected to terminal T6 (an example of the other measurement current supply point) connected to the connection point of electrochemical cells C5 and C6 connected in series. In this case, terminal T6 functions as the other measurement current supply point Ps3. As with connection points Pc1 and Pc2, wires or the like may be connected to a 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 each of the extended wires 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 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 that functions as one of the measurement current supply points in the first switching state, and an electrochemical cell C1 connected to terminal T1 (terminal T1 is clamped by the current sensor 5-1). A current sensor 5-2 is placed between a connection point Pc2 defined on the side of the other terminal of the pair of connection points Pc1 and Pc2 (terminal T11 in this example), and a measurement current supply point Ps2 that functions as one of the measurement current supply points in the second switching state and an electrochemical cell C10 connected to terminal T11 (an example of the other terminal) that functions 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, the impedance between both ends of each of the five electrochemical cells C1 to C5 in the DUT under test is measured. To do this, a measurement start switch (not shown) is operated. This causes the processing unit 6 to output a frequency control signal Sf to control the measurement current output unit 3 to output the measurement AC current Im, while also stopping the output of the control signal Sc. In this state, the scanner unit 2 is in the first switching state, so each of the switches S1, S2, S11 to S20 connects the fixed contact c with the movable contact a. Therefore, as shown in FIG. 3, a pair of input parts of voltage measurement unit 4-1 is connected to both ends of electrochemical cell C1, a pair of input parts of voltage measurement unit 4-2 is connected to both ends of electrochemical cell C2, a pair of input parts of voltage measurement unit 4-3 is connected to both ends of electrochemical cell C3, a pair of input parts of voltage measurement unit 4-4 is connected to both ends of electrochemical cell C4, and a pair of input parts of voltage measurement unit 4-5 is connected to both ends of electrochemical cell C5.

[0070] Furthermore, the measurement AC current Im output from the measurement current output unit 3 is supplied between the measurement current supply point Ps1 and the terminal T6 of the DUT under test. In this state, the measurement AC current Im flows through a current path IR1 consisting of one output unit of the measurement current output unit 3, the measurement current supply line Li, the scanner unit 2, the probe Pi1, the measurement current supply point Ps1, the terminal T1, the electrochemical cells C1 to C5, the terminal T6 of the DUT under test, the probe Pi3, the scanner unit 2, the measurement current supply line Li, and the other output unit of the measurement current output unit 3. , the measurement current supply line Li, inside the scanner unit 2, probe Pi1, 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 under test, probe Pi3, inside the scanner unit 2, and a current of value I2 flowing through a current path IR2 consisting of the measurement current supply line Li and the other output part of the measurement current output unit 3. Note that the DC current output from the power supply device PD flows through the electrochemical cells C1 to C10 in the DUT under test via connection points Pc1 and Pc2. In other words, the power line Lp is an active line through which DC 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 shunted and flows through the current path IR2 including the power supply device PD includes the five electrochemical cells C10 to C6 connected in series within that current path IR2. Therefore, 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. Meanwhile, the current value I1 of the measurement AC current Im that is shunted 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 shunted to the power supply device PD decreases, and the current value I1 of the measurement AC current Im shunted to the electrochemical cells C1 to C5 increases accordingly. As a result, the voltage values ​​V generated across each of the electrochemical cells C1 to C5 increase. This increases the ratio (S / N) of the signal level (S) of the measurement AC current Im to the noise level (N) of the end-to-end voltage V measured by each voltage measurement unit 4, thereby enabling highly accurate impedance measurement in the impedance calculation process (described later) performed by the processing unit 6. 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 DUT under measurement, and the current value I1 of the measurement AC current Im flowing through the electrochemical cells C1 to C5, and outputs current value data Di to the processing unit 6.

[0072] Furthermore, 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 ​​(the current value of the DC current and the current value I1 of the measurement AC current Im) included in the current value data Di. 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 is flowing through the measurement target DUT or 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 unnecessary.

[0075] The processing unit 6 also calculates the current value (I) of the measurement AC current Im flowing through the electrochemical cells C1 to 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 to C5 as voltage values ​​(V) based on the amplitudes of the AC voltages included in the voltage value data Dv1 to 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 to C5 that are the measurement target cells, and each of the AC voltages across each of the electrochemical cells C1 to C5 that are the measurement target cells, based on the corrected current value data Di and voltage value data Dv. Furthermore, the processing unit 6 measures (calculates) the impedances (impedance Z=V / I, R=Z·cos θ, X=Z·sin θ) 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] The processing unit 6 also sweeps the frequency of the measurement AC current Im by outputting a frequency control signal Sf to the measurement current output unit 3. The processing unit 6 then measures (calculates) the impedances of the electrochemical cells C1 to C5, which are the cells to be measured, at multiple 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 multiple frequencies. In this case, the processing unit 6 acquires, as frequency characteristics, a Cole-Cole plot showing the impedance characteristics of the electrochemical cell C with respect to frequency, and a Bode plot showing the gain characteristics and phase characteristics with respect to frequency. The processing unit 6 then outputs display data Dd to the output unit 7, causing the display device of the output unit 7 to display the measured impedances of the electrochemical cells C1 to C5 and the acquired Cole-Cole plots and Bode plots. This completes the process of measuring the impedances of the electrochemical cells C1 to C5, which are the cells to be measured, by the processing unit 6.

[0077] Next, a measurement method for measuring the impedance of each of the electrochemical cells C10 to C6, with the exception of the electrochemical cells C1 to C5, is described. Note that, hereinafter, redundant descriptions of the processing content and impedance measurement method by the impedance measuring device 1 that are the same as those in the above 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 a second switching state, and each of the switches S1, S2, S11 to S20 connects its fixed contact c to its movable contact b. Therefore, as shown in FIG. 4 , a pair of input terminals of the voltage measurement unit 4-1 is connected to both ends of the electrochemical cell C10, a pair of input terminals of the voltage measurement unit 4-2 is connected to both ends of the electrochemical cell C9, a pair of input terminals of the voltage measurement unit 4-3 is connected to both ends of the electrochemical cell C8, a pair of input terminals of the voltage measurement unit 4-4 is connected to both ends of the electrochemical cell C7, and a pair of input terminals of the voltage measurement unit 4-5 is connected to both ends of the electrochemical cell C6.

[0079] The measurement AC current Im output from the measurement current output section 3 is supplied between the measurement current supply point Ps2 and the terminal T6 of the DUT under test. In this state, the measurement AC current Im is divided into a current with a current value I3 flowing through a current path IR3 consisting of one output portion of the measurement current output portion 3, the measurement current supply line Li, the scanner portion 2, probe Pi2, the measurement current supply point Ps2, terminal T11, electrochemical cells C10 to C6, terminal T6 of the DUT under test, probe Pi3, the scanner portion 2, the measurement current supply line Li, and the other output portion of the measurement current output portion 3, and a current with a current value I4 flowing through a current path IR4 consisting of one output portion of the measurement current output portion 3, the scanner portion 2, probe Pi2, the measurement current supply point Ps2, terminal T11, connection point Pc2, the power supply line Lp, the power supply device PD, the power supply line Lp, connection point Pc1, terminal T1, electrochemical cells C1 to C5, terminal T6 of the DUT under test, probe Pi3, the scanner portion 2, the measurement current supply line Li, and the other output portion of the measurement current output portion 3. The DC current output from the power supply device PD flows through the electrochemical cells C1 to C10 in the DUT via the connection points Pc1 and Pc2. In other words, the power supply line Lp is an active line through which a DC 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 shunted and flows through the current path IR4 including the power supply device PD includes the five electrochemical cells C1 to C5 connected in series within that current path IR4. Therefore, 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. Meanwhile, the current value I3 of the measurement AC current Im that is shunted 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 shunted to the power supply device PD decreases, and the current value I3 of the measurement AC current Im shunted to the electrochemical cells C10 to C6 increases accordingly. As a result, the voltage values ​​V generated across each of the electrochemical cells C10 to C6 increase. This increases the ratio (S / N) of the signal level (S) of the measurement AC current Im to the noise level (N) of the end-to-end voltage V measured by each voltage measurement unit 4, thereby enabling highly accurate impedance measurement in the impedance calculation process (described later) performed by the processing unit 6. 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 DUT under measurement, 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] Furthermore, 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, so that 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 to 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 to C6 as voltage values ​​(V) based on the amplitudes of the AC voltages included in the voltage value data Dv1 to 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 to C6 that are the measurement target cells, and each of the AC voltages generated across each of the electrochemical cells C10 to C6 that are the measurement target cells, based on the corrected current value data Di and voltage value data Dv. Furthermore, based on the current value (I), voltage value (V), and phase difference (θ) calculated in this manner, the processing unit 6 measures (calculates) the impedances (impedance Z=V / I, R=Z·cos θ, X=Z·sin θ) of the electrochemical cells C10 to C6, which are the measurement target cells.

[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, which are the measurement target cells. Thereafter, the processing unit 6 outputs display data Dd to the output unit 7, causing 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, which are the measurement target cells, by the processing unit 6.

[0086] The processing unit 6 also calculates the impedance of the DUT under test as the sum of the impedances of all electrochemical cells C1 to C5 (measurement target cells) calculated in the first switching state and the impedances of all electrochemical cells C10 to C6 (measurement target cells) calculated in the second switching state. Next, the processing unit 6 acquires the frequency characteristics of the impedance of the DUT under test at each frequency (such as the Cole-Cole plot or Bode diagram described above) based on the frequency characteristics of the impedances of the electrochemical cells C10 to C6 (measurement target cells). The processing unit 6 then outputs display data Dd to the output unit 7, causing the display device of the output unit 7 to display the measured impedance of the DUT under test and the acquired Cole-Cole plot or Bode diagram. This completes the impedance measurement process for the DUT under test by the processing unit 6.

[0087] In this way, in the impedance measuring device 1 and the impedance measuring method, a current path (current path IR1 or 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 the connection point (terminal T6 in this example) of any two cells (electrochemical cells C5 and 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 arranged at a connection point (in this example, connection point Pc1) defined on the side of one terminal (in this example, terminal T1) of the pair of connection points Pc1, Pc2, and between one measurement current supply point (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, power supply device PD) is connected in parallel to a DUT under test that is configured to include 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 the measurement target cells, it is possible to supply a measurement AC current Im 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 it is possible to reliably measure the impedance of the measurement target cells (in this example, electrochemical cells C1 to C5).

[0089] Furthermore, in this impedance measurement device 1 and impedance measurement method, some cells (in this example, electrochemical cells C1 to C5) among a plurality of cells (in this example, electrochemical cells C1 to C10) are used as 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, measurement current supply point Ps1) and the other measurement current supply point (in this example, measurement current supply point Ps3) defined on one terminal (in this example, terminal T1) of a pair of terminals (in this example, terminals T1 and T11). Therefore, a current path IR2 through which the measurement AC current Im flows on the power supply line Lp includes one or more measurement target cells (in this example, five electrochemical cells C10 to C6) with a relatively high impedance. Therefore, even if the power supply device PD has a low impedance, the impedance of the current path IR2 as a whole will be large. Therefore, with this impedance measuring device 1 and 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, electrochemical cells C1 to C5) can be increased accordingly, resulting in an increase in the voltage value across the measurement target cells. As a result, with this impedance measuring device 1 and impedance measuring method, the ratio (S / N) of the signal level (S) to the noise level (N) of the measured voltage across the measurement target cells can be sufficiently increased, and the impedance of the measurement target cells can be measured with sufficiently high accuracy.

[0090] Furthermore, with this impedance measuring device 1 and impedance measuring method, the power supply device PD is not the object of measurement, the electrolytic device is the DUT to be measured, 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 used as the cells to be measured to measure impedance. This makes it possible to reliably measure the impedance of the cells to be measured (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 DUT to be measured.

[0091] Furthermore, this 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 of a pair of terminals (in this example, terminal T1) and a second switching state in which any one of the terminals is the other of the pair of terminals (in this example, terminal T11), 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) that are connected to the voltage measurement unit (in this example, voltage measurement units 4-1 to 4-5). By controlling the switching of switch S1 and switches S11 to S20, the processing unit 6 can automatically switch the connection between the voltage measurement unit and the two groups of measurement target cells 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] Furthermore, in this 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 the 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 same to the processing unit 6. The second current sensor (current sensor 5-2 in this example) is arranged on one of the pair of connection points (connection points Pc1 and Pc2 in this example). and a connection point (in this example, connection point Pc2) defined on the other terminal side (terminal T11 in this example), and one of the measurement current supply points (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). The processing unit 6 controls the switching of a third switch (in this example, switch S2) so that when the first switch (in this example, switch S1) is switched to the first switching state, 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), and when the first switch is switched to the second switching state, the processing unit 6 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).

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

[0095] Furthermore, according to this impedance measuring device 1 and 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 to be measured.

[0096] Furthermore, with this impedance measuring device 1 and impedance measuring method, the performance and deterioration of the cells to be measured (in this example, electrochemical cells C1 to C10) can be determined by acquiring the frequency characteristics of the impedance of the cells to be measured at multiple frequencies.

[0097] Furthermore, according to the impedance measuring device 1 and the impedance measuring method, the frequency characteristics of the impedance of the DUT under test at a plurality of frequencies are acquired, thereby making it possible to determine the performance and degradation of the DUT under test.

[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 with high accuracy the performance and degradation of the cell to be measured or the DUT to be measured.

[0099] The present invention is not limited to the above-described embodiment and can be modified as appropriate. For example, in the above-described embodiment, five of the ten electrochemical cells C1 to C10 are used as measurement target cells in one impedance measurement. However, this is not limited to this, and a portion (one to nine) of all the electrochemical cells C1 to C10 can be used as measurement target cells in one impedance measurement. In this case, by using half of the electrochemical cells C constituting the DUT as measurement target cells in one impedance measurement, the impedance of all the electrochemical cells C can be measured in a short time by simply performing the impedance measurement 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 can be measured by voltage measurement unit 4-1, the voltage V2 across electrochemical cells C2 and C7 can be measured by voltage measurement unit 4-2, the voltage V3 across electrochemical cells C3 and C8 can be measured by voltage measurement unit 4-3, the voltage V4 across electrochemical cells C4 and C9 can be measured by voltage measurement unit 4-4, and the voltage V5 across electrochemical cells C5 and C10 can be measured by voltage measurement unit 4-5.

[0101] Although the 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, current sensor 5-1 is a clamp-type non-contact current sensor that is configured to be openable and closable. Therefore, in the second switching state, current sensor 5-1 can be opened and removed, and then clamped in 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 the example in which the current sensor 5 outputs the current value data Di has been described, 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, by connecting conductors to the terminals T1 and T11 and locating a shunt resistor in the middle of the conductors, the supply current value of the measurement AC current Im can be measured.

[0104] Furthermore, in the above embodiment, an example using switches S1, S2, and S11 to S20 was described, but in a configuration in which connection switching is performed manually, a configuration in which the placement of these switches S1, S2, and S11 to S20 is omitted can also be adopted.

[0105] Although an example of measuring the impedance of each electrochemical cell C has been described, this is not limiting. For example, when it is necessary to measure only the impedance of the DUT under test (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 ​​across the electrochemical cells C1 to C5 using a single voltage measurement unit 4, and the impedance of the electrochemical cells C10 to C6 as a whole may be measured by measuring the voltage values ​​across the electrochemical cells C10 to C6 using the same voltage measurement unit 4, and the sum of the measured impedances may be calculated as the impedance of the DUT under test. Furthermore, the voltage values ​​across multiple electrochemical cells C out of the 10 electrochemical cells C may be measured using a single voltage measurement unit 4 to measure the impedance of the multiple electrochemical cells C as a whole. Furthermore, although the above embodiment has described an example of measuring the impedance of all the electrochemical cells C, it is also possible to measure the impedance of only a specific electrochemical cell C.

[0106] Furthermore, in the above-described embodiment, the other measurement current supply point (measurement current supply point Ps3 in this example) is defined as the connection point of two series-connected electrochemical cells C5 and C6 so that the measurement target cell (electrochemical cells C1-C5 or electrochemical cells C10-C6 in this example) is included in the current path (current path IR1 or current path IR3 in this example) between one 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. For example, when electrochemical cells C1-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 series-connected electrochemical cells C6 and C7, electrochemical cells C7 and C8, electrochemical cells C8 and C9, or electrochemical cells C9 and C10, as long as the measurement target cell is included in the current path. Similarly, for example, when electrochemical cells C10 to C6 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 series-connected electrochemical cells C5 and C4, electrochemical cells C4 and C3, electrochemical cells C3 and C2, or electrochemical cells C2 and C1. However, when measuring the impedance of some or all of the electrochemical cells C by two impedance measurements, it is preferable to define the connection point as the connection point of the two electrochemical cells C, C (in this example, electrochemical cells C5 and C6) located toward the center of the measurement target DUT in each impedance measurement, because this eliminates the need to switch the connection of probe Pi3 to the terminals of the measurement target DUT.

[0107] Although the above examples have been described using an electrolytic device as the DUT, other DUTs may also be used, such as electrolytic reduction devices, devices using ion exchange membranes, fuel cells, lithium ion batteries, and lead-acid batteries. Known examples of electrolytic reduction devices include organic electrolytic reduction devices used in the production of methylcyclohexane (MCH), a hydrogen carrier (see JP 2022-30943 A).

[0108] According to the present invention, even when a low-impedance non-measurement object is connected in parallel to the measurement object, by designating some of the multiple impedance elements as the measurement object impedance element, it is possible to supply a 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 ensuring reliable measurement of 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.

[0109] 1 Impedance measuring device 2 Scanner unit 3 Measurement current output unit 4-1 to 4-5 Voltage measuring unit 5-1, 5-2 Current sensor 6 Processing unit C1 to C10 Electrochemical cell Di Current value data DUT Measurement object Dv1 to Dv5 Voltage value data Lc Connection line Li Measurement current supply line Pc1, Pc2 Connection point PD Power supply unit Ps1 to Ps3 Measurement current supply point

Claims

1. An impedance measuring device comprising: a measurement object configured to include a plurality of impedance elements connected in series between a pair of terminals, and a non-measurement object connected in parallel via connection lines connected to a pair of connection points defined on the side of the pair of terminals, the measurement current supply unit supplies a measurement AC current to the measurement object 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 one of the pair of terminals, with a portion of the plurality of impedance elements as the measurement object impedance element; a first current sensor that measures a supply current value of the measurement AC current supplied to the measurement object impedance element; a voltage measurement unit that measures a voltage value of a voltage across both ends of the measurement object impedance element; and a processing unit that calculates an impedance of the measurement object impedance element based on the measured supply current value and the voltage value of the voltage across both 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 multiple impedance elements connected in series, and 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. An impedance measuring device as described in claim 1, in which a power supply device is treated as the non-measurement object, and either an electrolysis device or an electrolysis reduction device having a plurality of impedance elements is treated as the measurement object, and the impedance is measured by using some of the plurality of impedance elements as the measurement object impedance elements.

3. An impedance measuring device as described in claim 1, comprising: 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, wherein the processing unit controls the switching of the first switch and the second switch.

4. The impedance measuring device of claim 3, wherein 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 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 impedance measuring device according to claim 3, further comprising: a first current sensor arranged on the one terminal side; a second current sensor arranged on the other terminal side and measuring a supply current value of the measurement AC current being supplied to the impedance element to be measured; and a third switch switching between the supply current value measured by the first current sensor and the supply current value measured by the second current sensor and outputting the supply current value measured by the second current sensor to the processing unit; the second current sensor being 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 controlling the switching of the third switch to input the supply current value measured by the first current sensor in the first switching state and to input the supply current value measured by the second current sensor in the second switching state.

6. The impedance measuring device according to claim 5, wherein the first current sensor and the second current sensor are constituted by clamp-type non-contact current sensors that are configured to be able to be opened and closed.

7. The impedance measuring device according to claim 1, wherein the measurement current supply unit is configured 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.

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. The impedance measuring device according to claim 7 or 8, wherein the processing unit obtains, as the frequency characteristic, either a Cole-Cole plot or a Bode plot.

10. An impedance measurement method comprising the steps of: a measurement target configured with a plurality of impedance elements connected in series between a pair of terminals; a non-measurement target connected in parallel to the measurement target via connection lines connected to a pair of connection points defined on the side of the pair of terminals; 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; and measuring the impedance of the measurement target impedance element based on the measured supply current value and the voltage value of the voltage across both ends, the impedance element to be measured is supplied with the measurement AC current via the pair of measurement current supply lines respectively connected to the 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, the other measurement current supply point being connected to the 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 the one of the terminals, and the first current sensor is disposed between the impedance element to be measured and the one measurement current supply point.

11. An impedance measurement method as described in claim 10, in which a power supply device is treated as the non-measurement object, and either an electrolysis device or an electrolysis reduction device having a plurality of impedance elements is treated as the measurement object, and the impedance is measured by using some of the plurality of impedance elements as the measurement object impedance elements.

12. 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 either a Cole-Cole plot or a Bode plot is obtained as the frequency characteristic.

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