Impedance measuring apparatus and impedance measuring method

Abstract

To measure the impedance of an impedance element to be measured when an object to be measured is connected in parallel with an object to be measured constituted by connecting a plurality of impedance elements in series.SOLUTION: Supplying a measuring alternating current Im1 to the electrochemical cells C1 to C5, and supplying a measuring alternating current Im1 to the electrochemical cells C10 to C6, the measuring alternating current Im1 and the measuring alternating current Im2 being synchronized in magnitude, frequency, and phase to reduce a magnitude of a measuring alternating current flowing through the power supply device PD by canceling each other out; The impedance of the electrochemical cells C1 to C5 is calculated on the basis of the current values of the measuring alternating current Im1 flowing through the electrochemical cells C1 to C5 and the volts alternating current generated between both ends of the electrochemical cells C1 to C5, and the impedance of the electrochemical cells C10 to C6 is calculated on the basis of the current values of the measuring alternating current flowing through the electrochemical cells to and the volts alternating current generated between both ends of the electrochemical cells to. Im2 C6 C10 C10 C6.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[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. [Background technology]

[0002] The impedance measuring device disclosed in the following patent document is known as an impedance measuring device capable of measuring the impedance of a measurement object 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 a load as a measurement object is connected in parallel with the secondary battery as the measurement object 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, an AC voltage is generated across the detection resistor due to the flow of the feedback current. 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 to the calculation control unit. Next, the calculation control unit calculates the internal impedance of the secondary battery based on the AC current value indicated by the input AC current data and the voltage value across the secondary battery indicated by the input AC voltage data. [Prior art documents] [Patent documents]

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

[0005] However, the above-described impedance measuring device has the following problem. As conceptually shown in FIG. 6 , the problem of measuring the impedance of an operating DUT under test using the above-described impedance measuring device 1X will be specifically described. In this case, the DUT under test is connected in parallel to a power supply device PD that supplies a DC current to the DUT under test via a power supply line Lp serving as a connection line. Therefore, when measuring the impedance of an operating DUT under test, an AC current supply unit U1 supplies a measurement AC current Im to the DUT under test via a measurement current supply line Li and terminals T1 and T11 at both ends of the DUT under test. In this state, a current sensor U4 measures the current value of the measurement AC current Im flowing through the DUT under test, and an AC voltage detection unit U2 detects the voltage value of the AC voltage generated between terminals T1 and T11 of the DUT under test. 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. 6, 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 the DUT under test. Therefore, this impedance measurement device 1X has a problem in that it cannot measure the impedance of the DUT under test when a low-impedance object to be measured is connected in parallel to the DUT under test.

[0007] The present invention has been made in consideration of such problems, and 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. [Means for solving the problem]

[0008] In order to achieve the above object, an impedance measuring device according to the present invention is an impedance measuring device in a state in which a non-measurement object is connected in parallel to a measurement object configured to include a plurality of impedance elements connected in series between a pair of terminals, the impedance measuring device comprising: a measurement current supply unit that supplies a measurement AC current to a measurement object impedance element among the plurality of impedance elements; a current detection unit that measures a supply current value of the measurement AC current being supplied to the measurement object impedance element; a voltage measurement unit that measures a voltage value of a terminal voltage across 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 terminal voltage, wherein the measurement current supply unit is configured to include a first current supply unit and a second current supply unit, and the first current supply unit has a first measurement current supply point defined on the side of one of the pair of terminals, and a second measurement current supply point defined on the connection point of any two of the plurality of impedance elements that are connected in series. The second current supply unit supplies a first measurement current as the measurement AC current to the impedance elements in the first group located between a third measurement current supply point defined on the other terminal side of the pair of terminals and the second measurement current supply point, and the second current supply unit supplies a second measurement current, the amplitude, frequency and phase of which are synchronized with the first measurement current, to the impedance elements in the second group located between the second measurement current supply point and a third measurement current supply point defined on the other terminal side of the pair of terminals so that the first measurement current and the second measurement current cancel each other out and the amplitude of the measurement AC current flowing through the non-measurement object becomes small. the current detection unit is configured to include a first current sensor and a second current sensor, the first current sensor measures a first current value for calculating a supply current value of the measurement AC current flowing through the impedance elements in the first group, and the second current sensor measures a second current value for calculating a supply current value of the measurement AC current flowing through the impedance elements in the second group; the voltage measurement unit is configured to include a first measurement circuit and a second measurement circuit, and the first measurement circuitThe first voltage value of the AC voltage generated across the impedance element to be measured in the first group is measured, and the second measurement circuit measures a second voltage value of the AC voltage generated across the impedance element to be measured in the second group. The processing unit calculates the impedance of the impedance element to be measured in the first group based on the first current value measured by the first current sensor and the first voltage value measured by the first measurement circuit, and calculates the impedance of the impedance element to be measured in the second group based on the second current value measured by the second current sensor and the second voltage value measured by the second measurement circuit.

[0009] Furthermore, to achieve the above object, an impedance measurement method according to the present invention is an impedance measurement method in which, in a state in which a non-measurement object is connected in parallel to a measurement object configured to include a plurality of impedance elements connected in series between a pair of terminals, a measurement AC current is supplied to a measurement object impedance element among the plurality of impedance elements, a supply current value of the measurement AC current being supplied to the measurement object impedance element, a voltage value of a voltage across both ends of the measurement object impedance element, and 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, wherein the first measurement current is supplied as the measurement AC current to the impedance element in a first group located between a first measurement current supply point defined on the side of one of the pair of terminals and a second measurement current supply point defined on the side of the other of the pair of terminals, a second measurement current, the amplitude, frequency, and phase of which are synchronized with those of the first measurement current, are supplied as the measurement AC current to the impedance elements in a second group located between a current supply point and the second measurement current supply point so that the second measurement current and the first measurement current cancel each other out and the amplitude of the measurement AC current flowing through the non-measurement object is reduced; a first current value is measured for calculating a supply current value of the measurement AC current flowing through the impedance elements in the first group; a second current value is measured for calculating a supply current value of the measurement AC current flowing through the impedance elements in the second group; a first voltage value of an AC voltage generated across both ends of the measurement object impedance elements in the first group; a second voltage value of an AC voltage generated across both ends of the measurement object impedance elements in the second group;The impedance of the impedance element to be measured in the second group is calculated.

[0010] In this impedance measuring device and impedance measuring method, a first measurement AC current is supplied to the impedance elements in the first group, and a second measurement AC current is supplied to the impedance elements in the second group, the second measurement AC current having amplitude, frequency, and phase synchronized with the first measurement AC current so that the first measurement AC current and the second measurement AC current cancel each other out and the amplitude of the measurement AC current flowing through the non-measurement object is reduced.

[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, some or all of the plurality of impedance elements can be used as measurement object impedance elements, and a first measurement AC current can be supplied to the measurement object impedance elements in the first group, and a second measurement AC current can be supplied to the measurement object impedance elements in the second group.As a result, it is possible to measure the supply current value of the measurement AC current flowing through the measurement object impedance elements and the voltage value of the voltage across the measurement object impedance elements when the measurement AC current is supplied to the measurement object impedance elements, thereby enabling the impedance of the measurement object impedance elements to be reliably measured.

[0012] Furthermore, with this impedance measurement device and impedance measurement method, almost no measurement AC current is diverted to the non-measurement target, which results in a large current value for the first measurement AC current diverted to the measurement target impedance element and a large current value for the second measurement AC current diverted to the measurement target impedance element. As a result, the voltage values ​​of the end-to-end voltages generated across each of the impedance elements increase. As a result, with this impedance measurement device and impedance measurement method, the ratio (S / N) of the signal level (S) of the measurement AC current to the noise level (N) of the measured end-to-end voltage V can be sufficiently increased, allowing the impedance of the measurement target impedance element to be measured with sufficiently high accuracy.

[0013] In addition, the impedance measuring device of the present invention measures the impedance by treating a power supply device as the non-measurement object and either an electrolysis device or an electrolysis reduction device having a plurality of impedance elements as the measurement object, and measures the impedance by using some or all of the plurality of impedance elements as the measurement object impedance elements.

[0014] In addition, the impedance measurement method of the present invention measures the impedance by treating a power supply device as the non-measurement object and either an electrolysis device or an electrolysis reduction device having a plurality of impedance elements as the measurement object, and measuring the impedance by using some or all of the plurality of impedance elements as the measurement object impedance elements.

[0015] According to this impedance measuring device and impedance measuring method, when a power supply device with an extremely small output impedance is connected in parallel to the object to be measured, the impedance of the object to be measured can be reliably measured.

[0016] In addition, in the impedance measuring device of the present invention, the processing unit calculates the impedance of all impedance elements in the first group as the impedance elements to be measured, and calculates the impedance of all impedance elements in the second group as the impedance elements to be measured, and calculates the sum of the calculated impedance of all impedance elements to be measured in the first group and the calculated impedance of all impedance elements to be measured in the second group as the impedance of the object to be measured.

[0017] In addition, the impedance measurement method of the present invention calculates the impedance of all impedance elements in the first group as the impedance elements to be measured, and calculates the impedance of all impedance elements in the second group as the impedance elements to be measured, and calculates the sum of the calculated impedance of all impedance elements to be measured in the first group and the calculated impedance of all impedance elements to be measured in the second group as the impedance of the object to be measured.

[0018] In this impedance measuring device and impedance measuring method, the sum of the calculated impedances of all impedance elements in the first group and the calculated impedances of all impedance elements in the second group is calculated as the impedance of the measurement object. Therefore, with this impedance measuring device and impedance measuring method, the impedance of the measurement object can be measured with a single impedance measurement.

[0019] 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.

[0020] Moreover, the impedance measuring method according to the present invention measures the first current value and the second current value using a clamp-type non-contact current sensor that is configured to be openable and closable.

[0021] According to this impedance measuring device and impedance measuring method, the first current value and the second current value are measured using a clamp-type non-contact current sensor that is configured to be able to open and close, so that the first current sensor and the second current sensor can be attached to any position on the object to be measured.

[0022] In addition, in the impedance measuring device of the present invention, the first current sensor is placed at a position between the first measurement current supply point and the impedance element in the first group, and the second current sensor is placed at either a position between the third measurement current supply point and the impedance element in the second group, or a position between the second measurement current supply point and the output section of the second current supply section, and the processing section calculates the impedance of the impedance element to be measured in the first group using the first current value as the value of a supply current flowing through the impedance element to be measured in the second group, and calculates the impedance of the impedance element to be measured using the second current value as the value of a supply current flowing through the impedance element to be measured in the second group.

[0023] According to this impedance measuring device, the supply current value measured by the first current sensor and the second current sensor can be used as the current value of the measurement AC current flowing through the impedance element to be measured, and the impedance of the impedance element to be measured can be calculated.

[0024] In addition, in the impedance measuring device of the present invention, the first current sensor is arranged at a position between the first measurement current supply point and the impedance element in the first group, and the second current sensor is arranged at a position between the second measurement current supply point and each output part of the first current supply unit and the second current supply unit, and the processing unit calculates the impedance of the impedance element to be measured in the first group by using the first current value as the supply current value flowing through the impedance element to be measured in the first group, and calculates the impedance of the impedance element to be measured by using the current value obtained by subtracting the first current value from the second current value as the supply current value flowing through the impedance element to be measured in the second group.

[0025] According to this impedance measuring device, the processing unit calculates the impedance of the impedance element by using the current value of the second measurement AC current obtained by subtracting the current value measured by the first current sensor from the current value measured by the second current sensor as the supply current value flowing through the impedance elements in the second group, thereby being able to calculate the current value of the measurement AC current flowing through the impedance element to be measured.

[0026] In addition, in the impedance measuring device of the present invention, the first current supply unit and the second current supply unit supply the first measurement current and the second measurement current, respectively, at a position where the difference between the number of impedance elements in the first group and the number of impedance elements in the second group is within a value of 1, as the second measurement current supply point.

[0027] In addition, the impedance measurement method of the present invention supplies the first measurement current and the second measurement current at a position where the difference between the number of impedance elements in the first group and the number of impedance elements in the second group is within a value of 1 as the second measurement current supply point.

[0028] According to this impedance measuring device and impedance measuring method, the current value of the first measurement AC current flowing through the impedance element to be measured and the current value of the second measurement AC current flowing through the impedance element to be measured can be increased, and the current value of the measurement AC current flowing through the non-measurement element, which is included in the current value of the measurement AC current measured by the first current sensor and the second current sensor, can be sufficiently reduced, thereby making it possible to measure the impedance of the impedance element to be measured with sufficiently high accuracy.

[0029] In this impedance measuring device, the first current supply unit and the second current supply unit are configured by electronic loads.

[0030] This impedance measuring device consumes DC power output from the non-measurement target to generate a measurement AC current, so it can generate a large measurement AC current. Therefore, this impedance measuring device can calculate large current and voltage values, so it can measure (calculate) the impedance of the measurement target impedance element with high accuracy.

[0031] In addition, in the impedance measuring device of the present invention, the first measurement current supply unit and the second measurement current supply unit are each 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 first measurement current supply unit and the second 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 a plurality of frequencies.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] In addition, in the impedance measuring device of the present invention, when the phase value of the calculated impedance of the impedance element to be measured is not within the range of -90° to +90°, the processing unit notifies that there is an error in the calculated impedance value or that there is an error in the wiring of the first current sensor and the second current sensor.

[0041] This impedance measuring device can prompt the user to correctly reconnect the first current sensor and the second current sensor.

[0042] In addition, in the impedance measuring device of the present invention, when the phase value of the calculated impedance of the impedance element to be measured is not within the range of -90° to +90°, the processing unit swaps the first current value and the second current value to calculate the impedance of the impedance element to be measured.

[0043] This impedance measuring device can accurately measure (calculate) the impedance element to be measured and the impedance of the object to be measured. [Effects of the Invention]

[0044] 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 multiple impedance elements, it is possible to measure the supply current value of the measurement AC current flowing 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 making it possible to reliably measure the impedance of the measurement object impedance element. [Brief explanation of the drawings]

[0045] [Figure 1] 1 is a diagram showing the configuration of an impedance measuring device 1. FIG. [Figure 2]FIG. 2 is an explanatory diagram for explaining the operation of the impedance measuring device 1. [Figure 3] FIG. 1 is a diagram showing the configuration of an impedance measuring device 1A. [Figure 4] FIG. 2 is a diagram showing the configuration of an impedance measuring device 1B. [Figure 5] FIG. 1 is a diagram showing the configuration of an impedance measuring device 1C. [Figure 6] FIG. 1 is an explanatory diagram illustrating how to use a conventional impedance measuring device 1X. DETAILED DESCRIPTION OF THE INVENTION

[0046] 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.

[0047] 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 where a measurement target configured by connecting multiple impedance elements in series is connected in parallel to a non-measurement target via a power supply line Lp as a connection line.

[0048] In this case, the measurement target may be an electrolysis device (electrolysis device) in which multiple electrochemical cells (an example of impedance elements) are electrically connected in series to form a stack; an electrolysis reduction device (electrolysis reduction device) in which multiple electrolyte membranes (an example of impedance elements) are electrically connected in series to form a stack; an ion exchange membrane device in which multiple ion exchange membranes (an example of impedance elements) are electrically connected in series to form a stack; a fuel cell in which multiple power generation cells (an example of impedance elements) 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 impedance elements) 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 the measurement target DUT, and a power supply device PD that supplies power to the measurement target DUT is the non-measurement target.

[0049] 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 a plurality of electrochemical cells C1 to C10 (hereinafter, also referred to as "electrochemical cells C" when not distinguishing between them) in a stacked configuration. Note that an electrolysis device is actually configured by connecting tens to hundreds of electrochemical cells C in series, but 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 each connection point of the electrochemical cells C, C, respectively.

[0050] (First Example) Next, we will explain the configuration of impedance measuring device 1. As shown in Fig. 1, impedance measuring device 1 is configured to include measurement current output units 2-1 and 2-2 (hereinafter also referred to as "measurement current output unit 2" when not distinguished), voltage measurement units 3-1 to 3-4 (hereinafter also referred to as "voltage measurement unit 3" when not distinguished), current sensors 4-1 and 4-2 (hereinafter also referred to as "current sensor 4" when not distinguished), processing unit 5, output unit 6, voltage detection probes P1 to P8 (hereinafter also referred to as "probe P" when not distinguished), and measurement current supply probes Pi1 to Pi3.

[0051] The measurement current output unit 2-1 functions as a first current supply unit that supplies a measurement AC current to the measurement target cell. In response to instructions from the processing unit 5, the measurement current output unit 2-1 generates and outputs a measurement AC current Im1 (first measurement current), which is a sinusoidal AC signal for measuring the impedance of the measurement target cell. Measurement current supply lines Li are connected to one output terminal and the other output terminal of the measurement current output unit 2-1. Therefore, the measurement current output unit 2-1 outputs the measurement AC current Im1 to the electrochemical cells C1 to C5, which are the measurement target cells, via the measurement current supply lines Li and Li and the probes Pi1 and Pi2. The measurement current output unit 2-1 is configured to be able to adjust the frequency of the measurement AC current Im1, and sweeps (varies) the frequency of the measurement AC current Im1 in accordance with a frequency control signal Sf1 output from the processing unit 5 before outputting the measurement AC current Im1.

[0052] The measurement current output unit 2-2 functions as a second current supply unit that supplies a measurement AC current to the measurement target cell. In response to instructions from the processing unit 5, it generates and outputs a measurement AC current Im2 (second measurement current), which is a sinusoidal AC signal for measuring the impedance of the measurement target cell. A measurement current supply line Li is connected to one output terminal and the other output terminal of the measurement current output unit 2-2. Therefore, the measurement current output unit 2-2 outputs the measurement AC current Im2 to the electrochemical cells C10 to C6, which are the measurement target cells, via the measurement current supply lines Li and Li and the probes Pi3 and Pi2. The measurement current output unit 2-2 is configured to vary the frequency of the measurement AC current Im2. In response to a frequency control signal Sf2 output from the processing unit 5, the measurement current output unit 2-2 sweeps (varies) the frequency of the measurement AC current Im2, which is synchronized with the measurement AC current Im1 in amplitude, frequency, and phase, and outputs the resulting frequency. In this case, the measurement current output units 2-1 and 2-2 constitute a measurement current supply unit.

[0053] When there is no need to distinguish between the measurement AC currents Im1 and Im2, they are also referred to as "measurement AC current Im." In the impedance measuring device 1 of this example, the other output portion of the measurement current output portion 2-1 and the other output portion of the measurement current output portion 2-2 are connected, and the other output portions of both measurement current output portions 2-1 and 2-2 are connected to a probe Pi2 by a single measurement current supply line Li. However, this configuration is not limited to this, and the other output portions of both measurement current output portions 2-1 and 2-2 can be connected to the same terminal T of the DUT under test by connecting two separate measurement current supply lines Li to the other output portions of both measurement current output portions 2-1 and 2-2, respectively, and using two probes.

[0054] The voltage measurement unit 3 measures the input voltage via a pair of probes P and P, and outputs voltage value data indicating the measured value to the processing unit 5. As shown in FIG. 1 , in this example, for example, the voltage measurement unit 3-1 is connected to terminals T1 and T4 of the DUT under test via probes P1 and P2, the voltage measurement unit 3-2 is connected to terminals T4 and T5 of the DUT under test via probes P3 and P4, the voltage measurement unit 3-3 is connected to terminals T5 and T6 of the DUT under test via probes P5 and P6, and the voltage measurement unit 3-4 is connected to terminals T6 and T11 of the DUT under test via probes P7 and P8. The voltage measurement units 3-1 to 3-3 constitute a first measurement circuit that measures a first voltage value of the AC voltage generated across the battery cells C in a first group G1 (described later), and the voltage measurement unit 3-4 constitutes a second measurement circuit that measures a second voltage value of the AC voltage generated across the battery cells C in a second group G2 (described later).

[0055] In this case, the voltage measurement unit 3-1, in accordance with instructions from the processing unit 5, measures the voltage generated between the probes P1 and P2 (the voltage V1 across both ends of the electrochemical cells C1 to C3 as the cells to be measured), and outputs voltage value data Dv1 indicating the measurement value (voltage value of the voltage across both ends: first voltage value) to the processing unit 5.

[0056] In accordance with instructions from the processing unit 5, the voltage measurement unit 3-2 measures the voltage generated between the probes P3 and P4 (the voltage V2 across both ends of the electrochemical cell C4 as the cell to be measured) and outputs voltage value data Dv2 indicating the measurement value (voltage value of the voltage across both ends: first voltage value) to the processing unit 5.

[0057] In accordance with instructions from the processing unit 5, the voltage measurement unit 3-3 measures the voltage generated between the probes P5 and P6 (the voltage V3 across both ends of the electrochemical cell C5 as the cell to be measured) and outputs voltage value data Dv3 indicating the measurement value (voltage value of the voltage across both ends: first voltage value) to the processing unit 5.

[0058] In accordance with instructions from the processing unit 5, the voltage measurement unit 3-4 measures the voltage generated between the probes P7 and P8 (end-to-end voltage V4 at both ends of the electrochemical cells C10 to C6 as the measurement target cells), and outputs voltage value data Dv4 indicating the measured value (voltage value of the end-to-end voltage: second voltage value) to the processing unit 5. Note that hereinafter, when the end-to-end voltages V1 to V4 are not distinguished, they are also referred to as "end-to-end voltage V," and when the voltage value data Dv1 to Dv4 are not distinguished, they are also referred to as "voltage value data Dv."

[0059] The current sensors 4-1 and 4-2 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 4 is configured with two semicircular magnetic cores 4a and 4b and a magnetic detection element 4c formed, for example, by a Hall element or a fluxgate element, and functions as a clamp-type contactless current sensor configured to be able to release (open and close) the clamped conductor by operating an operating unit (not shown) to bring the magnetic cores 4a and 4b close to each other and to move the magnetic cores 4a and 4b apart from each other. In current sensor 4, magnetic detection element 4c detects magnetic flux generated in magnetic cores 4a and 4b when a current flows through the conductor inserted in opening 4d, 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 Di1 and Di2 (hereinafter, also referred to as "current value data Di" when not distinguishing between them) indicating the measured current value. However, current sensor 4 can also be a type that can measure the current value of high-frequency signals other than DC, and instead of a clamp-type current sensor, a current sensor that uses an annular core and is configured to be unopenable can also be used.

[0060] The processing unit 5 is configured, for example, by a CPU and performs overall control of the impedance measuring device 1. Specifically, during impedance measurement, the processing unit 5 controls the measurement current output units 2-1 and 2-2 to generate and output measurement AC currents Im1 and Im2. During impedance measurement, as described below, the processing unit 5 measures (calculates) the impedances of the electrochemical cells C1 to C5 as a first group G1, with the electrochemical cells C1 to C3, C4, and C5 in the first group G1 as measurement target cells. During impedance measurement, the processing unit 5 measures (calculates) the impedances of the electrochemical cells C10 to C6 as a second group G2, with the electrochemical cells C10 to C6 in the second group G2 as measurement target cells.

[0061] Specifically, the processing unit 5 controls the current sensor 4 to measure the current flowing through the conductor (terminals T1 and T11 in this example) inserted into the opening 4d of the current sensor 4 and output the current value data Di, and also controls each voltage measurement unit 3 to measure the voltage between the probes P and P and output the voltage value data Dv. The processing unit 5 also inputs the current value data Di output from the current sensor 4 and the voltage value data Dv output from the voltage measurement unit 3. The processing unit 5 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 5 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 5 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 under test and the AC voltage occurring across the cell under test, based on the current value data Di and the voltage value data Dv. The processing unit 5 also measures (calculates) the impedance of the cell under test (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.

[0062] Furthermore, the processing unit 5 measures (calculates) the sum of the measured (calculated) impedances of all electrochemical cells C1 to C5 (part of the multiple cells (impedance elements)) in the first group G1 and the measured (calculated) impedances of all electrochemical cells C10 to C6 (part of the multiple cells (impedance elements)) in the second group G2 as the impedance (series impedance of electrochemical cells C1 to C10: impedance between terminals T1 to T11) of the entire DUT to be measured (i.e., all of the multiple cells (impedance elements)).

[0063] In addition, in accordance with instructions from an operation unit (not shown), processing unit 5 outputs a frequency control signal Sf to measurement current output unit 2 to synchronize the amplitude, frequency, and phase of measurement AC currents Im1 and Im2 and sweep them between the low frequency band and the high frequency band. Processing unit 5 also outputs display data Dd to output unit 6 for displaying the measured impedance of the cell under test, the impedance of the DUT under test as a whole, and the frequency characteristics of the impedance such as a Cole-Cole plot and Bode diagram (to be described later).

[0064] The output unit 6 is configured, for example, by a display device such as a liquid crystal panel or an organic EL panel, and receives the display data Dd output from the processing unit 5 to display on a screen the impedance of the cell under test, the impedance of the DUT under test as a whole, and the frequency characteristics of the impedance. Note that instead of a display device, the output unit 6 may be configured by 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 DUT under test as a whole, and the frequency characteristics of the impedance to this external device.

[0065] The probes P1 to P8 are contact-type probes whose tips are connected (contacted) to the terminals T of the DUT to be measured, respectively, to measure AC voltages as voltages across the terminals T, T when AC currents Im1, Im2 for measurement are supplied to the cells to be measured. The probes Pi1, Pi2, Pi3 are also contact-type probes whose tips are connected (contacted) to the terminals T of the DUT to be measured, respectively, to supply AC currents Im1, Im2 for measurement.

[0066] Next, an impedance measurement method for measuring (calculating) the impedance of the electrochemical cells C1 to C10 and measuring (calculating) the impedance of the entire DUT under measurement using the impedance measurement device 1 will be described with reference to the drawings.

[0067] The power supply device PD is connected to a pair of connection points defined on the side of the pair of terminals via connection lines. In this example, the power supply device PD is connected to a pair of connection points Pc1, Pc2 defined on the pair of terminals T1, T11 themselves via a power supply line Lp as a connection line. In this case, on the side of the pair of terminals, 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.

[0068] First, probes Pi1 to Pi3 are connected to terminal T of the DUT under test. In this case, a first measurement current supply point defined on one of the pair of terminals is defined as measurement current supply point Ps1, and a third measurement current supply point defined on the other of the pair of terminals is defined as measurement current supply point Ps3. Therefore, in this example, probe Pi1 is connected to measurement current supply point Ps1 defined on terminal T1 (one of the pair of terminals) of the DUT under test, and probe Pi3 is connected to measurement current supply point Ps3 defined on terminal T11 (the other of the pair of terminals) of the DUT under test. Also, as an example, a second measurement current supply point defined at the connection point of any two electrochemical cells C, C (impedance elements) connected in series among multiple electrochemical cells C (impedance elements) is defined as the connection point of electrochemical cells C5, C6. Therefore, in this example, probe Pi2 is connected to measurement current supply point Ps2 defined on terminal T6 of the DUT under test, which is connected to electrochemical cells C5, C6. As with the connection points Pc1 and Pc2, conductors or the like may be connected to the pair of terminals T1 and T11 on the side of the pair of terminals and extended, and measurement current supply points may be defined on the extended conductors or the like.

[0069] In this state, electrochemical cells C1 to C5 belong to the first group G1, and electrochemical cells C10 to C6 belong to the second group G2. In this example, the number of electrochemical cells C belonging to the first group G1 is equal to the number of electrochemical cells C belonging to the second group G2 (five), so the difference between the number of electrochemical cells C in the first group G1 and the number of electrochemical cells C in the second group G2 is within 1 (0 in this example). Therefore, the position of terminal T6 corresponds to "the position where the difference between the number of impedance elements in the first group G1 and the number of impedance elements in the second group G2 is within 1." Here, as will be described later, when this difference is 0, the impedance of the DUT under measurement can be measured with the highest accuracy.

[0070] Next, probes P1 and P2 are connected to terminals T1 and T4 of the DUT under test, probes P3 and P4 are connected to terminals T4 and T5 of the DUT under test, probes P5 and P6 are connected to terminals T5 and T6 of the DUT under test, and probes P7 and P8 are connected to terminals T6 and T11 of the DUT under test. In this state, electrochemical cells C1 to C3, C4, C5, C10 to C6 are the cells under test.

[0071] Next, the current sensor 4-1 is placed at a position between the connection point Pc1 and the measurement current supply point Ps1 and the electrochemical cell C1 connected to the terminal T1 (terminal T1 is clamped by the current sensor 4-1). Also, the current sensor 4-2 is placed at a position between the connection point Pc2 and the measurement current supply point Ps3 and the electrochemical cell C10 connected to the terminal T11 (terminal T11 is clamped by the current sensor 4-2).

[0072] Next, a measurement start switch (not shown) is operated. This causes the processing unit 5 to output a frequency control signal Sf1 to control the measurement current output unit 2-1 to output a measurement AC current Im1, and to output a frequency control signal Sf2 to control the measurement current output unit 2-2 to output a measurement AC current Im2. At this time, the measurement current output units 2-1 and 2-2 output measurement AC currents Im1 and Im2, respectively, whose amplitudes, frequencies, and phases are synchronized with each other, in accordance with the frequency control signals Sf1 and Sf2.

[0073] In this case, the measurement AC current Im1 output from the measurement current output section 2-1 is supplied between the measurement current supply point Ps1 and the terminal T6 of the DUT under test. As shown in Figure 2, in this state, the measurement AC current Im1 is divided into a current with a current value I1 that flows through a current path IR1 consisting of one output part of the measurement current output part 2-1, the measurement current supply line Li, the probe Pi1, the measurement current supply point Ps1, terminal T1, electrochemical cells C1 to C5, terminal T6 (measurement current supply point Ps2), the probe Pi2, and the measurement current supply line Li, and a current with a current value I2 that flows through a current path IR2 consisting of one output part of the measurement current output part 2-1, the measurement current supply line Li, the probe Pi1, the measurement current supply point Ps1, terminal T1, connection point Pc1, the power supply line Lp, the power supply device PD, the power supply line Lp, connection point Pc2, terminal T11, the electrochemical cells C10 to C6, terminal T6, the probe Pi2, the measurement current supply line Li, and the other output part of the measurement current output part 2-1. The DC current output from the power supply device PD flows through the electrochemical cells C1 to C10 in the DUT under test via the connection points Pc1 and Pc2. In other words, the power supply line Lp is an active line through which a DC current flows.

[0074] Furthermore, the measurement AC current Im2 output from the measurement current output section 2-2 is supplied between the measurement current supply point Ps2 and the terminal T6 of the DUT under test. As shown in Figure 2, in this state, the measurement AC current Im2 is divided into a current with a current value I3 that flows through a current path IR3 consisting of one output part of the measurement current output part 2-2, the measurement current supply line Li, probe Pi3, the measurement current supply point Ps3, terminal T11, electrochemical cells C10 to C6, terminal T6 (measurement current supply point Ps2), probe Pi2, and the measurement current supply line Li, and a current with a current value I4 that flows through a current path IR4 consisting of one output part of the measurement current output part 2-2, the measurement current supply line Li, probe Pi3, the measurement current supply point Ps3, 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, probe Pi2, the measurement current supply line Li, and the other output part of the measurement current output part 2-2. In FIG. 2, in order to facilitate understanding of the current paths IR1 to IR4, components that are less related to these current paths IR1 to IR4 are not shown.

[0075] In this example, the number of electrochemical cells C included in the current path IR2 (five in this example) is equal to the number of electrochemical cells C included in the current path IR4 (five in this example). Therefore, the impedance of the current path IR2 with respect to the measurement AC current Im1 is approximately equal to the impedance of the current path IR4 with respect to the measurement AC current Im2. Therefore, the current value I2 of the measurement AC current Im1 flowing through the current path IR2 is approximately equal to the current value I4 of the measurement AC current Im2 flowing through the current path IR4. The measurement AC currents Im1 and Im2 are synchronized with each other in amplitude, frequency, and phase. The measurement current output unit 2-2 supplies the measurement AC current Im2 whose amplitude, frequency, and phase are synchronized with those of the measurement AC current Im1 so that the measurement AC current Im2 and the measurement AC current Im1 cancel each other out and the amplitude of the measurement AC currents (Im1 and Im2) flowing through the power supply device PD is reduced. As a result, the current value of the measurement AC current Im flowing through the power supply device PD becomes approximately 0 A because the measurement AC current Im1 and the measurement AC current Im2 cancel each other out. Therefore, the measurement AC current Im is not actually flowing through the power supply device PD. In other words, the impedance of the power supply device PD becomes infinitely large with respect to the measurement AC current Im.

[0076] On the other hand, when the impedance of the power supply device PD is extremely small compared to the impedance of the DUT under test, both ends of the DUT under test are short-circuited, and as a result, almost no measurement AC currents Im1 and Im2 flow through the current paths IR1 and IR3. In contrast, when the impedance of the power supply device PD is infinitely large compared to the measurement AC current Im, the measurement AC current Im1 does not flow through the current path IR2, and therefore flows through the current path IR1 at a sufficiently large current value I1, and the measurement AC current Im2 does not flow through the current path IR4, and therefore flows through the current path IR3 at a sufficiently large current value I3.

[0077] At this time, current sensor 4-1 measures the current value of the current flowing through terminal T1 inserted (clamped) into opening 4d. In this case, because measurement AC current Im2 does not flow through current path IR4, current sensor 4-1 measures current value I1 of measurement AC current Im1 flowing only through current path IR1 and the current value of the DC current output from power supply device PD and flowing through DUT under measurement, and outputs current value data Di1 to processing unit 5. Therefore, current sensor 4-1 accurately measures current value I1 (first current value) of measurement AC current Im1 flowing through electrochemical cells C1 to C5, which are the measurement target cells. In addition, current sensor 4-2 measures the current value of the current flowing through terminal T11 inserted (clamped) into opening 4d. In this case, because the measurement AC current Im1 does not flow through the current path IR2, the current sensor 4-2 measures the current value I3 of the measurement AC current Im2 that flows only through the current path IR3 and the current value of the DC current that is output from the power supply device PD and flows through the DUT under measurement, and outputs current value data Di2 (second current value) to the processing unit 5. Therefore, the current sensor 4-2 accurately measures the current value I3 (second current value) of the measurement AC current Im2 that flows through the electrochemical cells C10 to C6, which are the cells under measurement.

[0078] Thus, because almost no measurement AC currents Im1 and Im2 are shunted to the power supply device PD, the current value I1 of the measurement AC current Im1 shunted to the electrochemical cells C1 to C5, which are the measurement target cells, and the current value I3 of the measurement AC current Im2 shunted to the electrochemical cells C10 to C6, which are the measurement target cells, become large. As a result, the voltage value of each end-to-end voltage V generated across each of the electrochemical cells C1 to C10 becomes large. This increases the ratio (S / N) of the signal level (S) of the measurement AC currents Im1 and Im2 to the noise level (N) of the end-to-end voltage V measured by each voltage measurement unit 3, and therefore the impedance can be measured with high accuracy in the impedance calculation process performed by the processing unit 5, which will be described later.

[0079] In addition, voltage measurement unit 3-1 measures the voltage V1 (voltage across both ends) at both ends of electrochemical cells C1 to C3 and outputs voltage value data Dv1 to processing unit 5, voltage measurement unit 3-2 measures the voltage V2 (voltage across both ends) at both ends of electrochemical cell C4 and outputs voltage value data Dv2 to processing unit 5, voltage measurement unit 3-3 measures the voltage V3 (voltage across both ends) at both ends of electrochemical cell C5 and outputs voltage value data Dv3 to processing unit 5, and voltage measurement unit 3-4 measures the voltage V4 (voltage across both ends) at both ends of electrochemical cells C10 to C6 and outputs voltage value data Dv4 to processing unit 5.

[0080] Next, the processing unit 5 receives the current value data Di output from each current sensor 4 and the voltage value data Dv output from each voltage measurement unit 3. The processing unit 5 also measures (calculates) the impedance of each of the measurement target cells C1 to C3, C4, C5, and C10 to C6 based on the received current value data Di and voltage value data Dv.

[0081] Specifically, first, the processing unit 5 corrects the current value indicated by the current value data Di1 by subtracting the current value of the DC current from data indicating the current values ​​included in the current value data Di1 (the current value of the DC current and the current value I1 of the measurement AC current Im1). As a result, the current value indicated by the corrected current value data Di1 is the current value I1 (supply current value) of the measurement AC current Im1 flowing only through the electrochemical cells C1 to C5. Note that when no DC current is flowing through the DUT under measurement or when the current sensor 4-1 is a current sensor that does not detect DC current, the current value indicated by the current value data Di1 is only the current value I1 of the measurement AC current Im1, and therefore the process of subtracting the current value of the DC current from the current value data Di1 to correct the current value indicated by the current value data Di1 is unnecessary.

[0082] Similarly, the processing unit 5 corrects the current value indicated by the current value data Di2 by subtracting the current value of the DC current from data indicating the current values ​​included in the current value data Di2 (the current value of the DC current and the current value I3 of the measurement AC current Im2). As a result, the current value indicated by the corrected current value data Di2 is the current value I3 (supply current value) of the measurement AC current Im2 flowing only through the electrochemical cells C10-C6. Note that when no DC current is flowing through the DUT under measurement or when the current sensor 4-2 is a current sensor that does not detect DC current, the current value indicated by the current value data Di2 is only the current value I3 of the measurement AC current Im2, and therefore the process of subtracting the current value of the DC current from the current value data Di2 to correct the current value indicated by the current value data Di2 is unnecessary.

[0083] The processing unit 5 also calculates the current value (I) of the measurement AC current Im1 flowing through the electrochemical cells C1-C5 based on the amplitude of the measurement AC current Im1 included in the corrected current value data Di1, and calculates the current value (I) of the measurement AC current Im2 flowing through the electrochemical cells C10-C6 based on the amplitude of the measurement AC current Im2 included in the corrected current value data Di2. The processing unit 5 also calculates the AC voltages across each of the electrochemical cells C1-C3, C4, C5, and C10-C6 as respective voltage values ​​(V) based on the amplitudes of the AC voltages included in the voltage value data Dv1-Dv4. Furthermore, based on the corrected current value data Di and voltage value data Dv, the processing unit 5 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-C3, C4, C5, C10-C6 that are the measurement target cells and each of the AC voltages generated across both ends of each of the electrochemical cells C1-C3, C4, C5, C10-C6 that are the measurement target cells. Based on the current value (I), voltage value (V), and phase difference (θ) calculated in this way, the processing unit 5 measures (calculates) the impedance (impedance Z=V / I, R=Z cos θ, X=Z sin θ) of each of the electrochemical cells C1-C3, C4, C5, C10-C6 that are the measurement target cells.

[0084] Furthermore, the processing unit 5 outputs a frequency control signal Sf1 to the measurement current output unit 2-1 and a frequency control signal Sf2 to the measurement current output unit 2-2, thereby synchronously sweeping the frequencies of the measurement AC currents Im1 and Im2. The processing unit 5 then measures (calculates) the impedance of each of the electrochemical cells C1 to C3, C4, C5, and C10 to C6, which are the cells to be measured, at multiple frequencies as described above. The processing unit 5 then acquires the frequency characteristics of the impedance of the electrochemical cells C1 to C3, C4, C5, and C10 to C6, which are the cells to be measured, at multiple frequencies. In this case, the processing unit 5 acquires, as the frequency characteristics, a Cole-Cole plot showing the impedance characteristics of the electrochemical cell C with respect to frequency, a Bode plot showing the gain characteristics and phase characteristics with respect to frequency, and the like. Thereafter, the processing unit 5 outputs the display data Dd to the output unit 6, and causes the measured impedances of the electrochemical cells C1 to C3, C4, C5, C10 to C6, and the acquired Cole-Cole plots and Bode diagrams to be displayed on the display device of the output unit 6. This completes the process of measuring the impedances of the electrochemical cells C1 to C3, C4, C5, C10 to C6, which are the cells to be measured, by the processing unit 5.

[0085] Thereafter, processing unit 5 calculates the sum of the calculated impedances of all electrochemical cells C1 to C3, C4, C5, C10 to C6, which are the cells under measurement, as the impedance of the DUT under measurement. Next, processing unit 5 acquires the frequency characteristics of the impedance of the DUT under measurement at each frequency (such as the Cole-Cole plot or Bode diagram described above) based on the frequency characteristics of the impedance of electrochemical cells C1 to C3, C4, C5, C10 to C6, which are the cells under measurement. Thereafter, processing unit 5 outputs display data Dd to output unit 6, and causes the display device of output unit 6 to display the measured impedance of the DUT under measurement and the acquired Cole-Cole plot or Bode diagram. This completes the process of measuring the impedance of the DUT under measurement, which is the measurement target, performed by processing unit 5.

[0086] In parallel with the impedance measurement process, the processing unit 5 also performs a verification process to check whether the measured (calculated) impedance value is correct. In this process, if the phase value of the measured (calculated) impedance of the cell under measurement is not within the range of -90° to +90°, the processing unit 5 outputs display data Dd to the output unit 6 to notify that there is an error in the calculated impedance value or an error in the wiring of the current sensors 4-1 and 4-2.

[0087] The phase value of the impedance of the measurement target cell is always within the range of −90° to +90°. Meanwhile, when measuring the impedance of each of the electrochemical cells C1 to C3, C4, C5, and C10 to C6, which are the measurement target cells, based on the calculated current value (I), voltage value (V), and phase difference (θ) in the impedance measurement process, if the current value data Di1 output from current sensor 4-1 and the current value data Di2 output from current sensor 4-2 are treated inversely due to incorrect wiring of current sensors 4-1 and 4-2, the phase difference (θ) will be inverted by 180°. Therefore, if such handling is performed in the impedance measurement process, the phase value of the measured (calculated) impedance of the measurement target cell will not be within the range of −90° to +90°. Therefore, the processing unit 5 can notify the user of the impedance measuring device 1 that there is an error in the calculated impedance value or that there is an error in the wiring of current sensors 4-1 and 4-2, thereby urging them to correctly connect current sensors 4-1 and 4-2.

[0088] Furthermore, when the phase value of the calculated impedance of the measurement target cell is not within the range of −90° to +90°, processing unit 5 swaps current value I1 indicated by display data Dd1 with current value I3 indicated by current value data Di2 to correctly measure the impedance of measurement target cells C1 to C3, C4, C5, C10 to C6, and outputs display data Dd to display the measured impedance of each electrochemical cell C1 to C3, C4, C5, C10 to C6, the acquired Cole-Cole plots and Bode plots for electrochemical cells C1 to C3, C4, C5, C10 to C6, the measured impedance of the measurement target DUT, and the acquired Cole-Cole plots and Bode plots for the measurement target DUT on output unit 6. At this time, a configuration may be adopted in which processing unit 5 is notified that there is an error in the calculated impedance value or that there is an error in the wiring of current sensors 4-1 and 4-2.

[0089] In this way, in this impedance measuring device 1 and impedance measuring method, a measurement AC current Im1 is supplied to the cells in the first group G1 (in this example, C1 to C5), and a measurement AC current Im2 whose amplitude, frequency and phase are synchronized with the measurement AC current Im1 is supplied to the cells in the second group G2 (in this example, C10 to C6) so that the measurement AC currents Im1 and Im2 cancel each other out and the amplitudes of the measurement AC currents Im1 and Im2 flowing through the power supply device PD become smaller. In the impedance measurement device 1 and the impedance measurement method, current value data Di1 is measured to calculate a current value I1 of a measurement AC current Im1 flowing through the electrochemical cells C1 to C5 in the first group G1, current value data Di2 is measured to calculate a current value I3 of a measurement AC current Im2 flowing through the electrochemical cells C10 to C6 in the second group G2, and voltage values ​​V1 to V3 of the AC voltages generated across the electrochemical cells C1 to C3, C4, and C5 in the first group G1 are measured. Then, a voltage value V4 of the AC voltage generated across both ends of the electrochemical cells C10 to C6 in the second group G2 is measured, and the impedance of the electrochemical cells C1 to C3, C4, and C5 in the first group G1 is calculated based on the measured current value I1 (first current value) and the measured voltage values ​​V1 to V3 (first voltage values), and the impedance of the electrochemical cells C10 to C6 in the second group G2 is calculated based on the measured current value I3 (second current value) and the measured voltage value V4 (second voltage value).

[0090] Therefore, according to the impedance measuring device 1 and the impedance measuring method, even when a low-impedance non-measurement target (in this example, a power supply device PD) is connected in parallel to a measurement target DUT configured with a plurality of electrochemical cells C1 to C10, some or all of the plurality of electrochemical cells C1 to C10 (in this example, the electrochemical cells C1 to C5 in the first group G1 and the battery cells C10 to C6 in the second group G2) are set as measurement target cells, and a measurement AC current is applied to the measurement target cells in the first group G1 (in this example, the electrochemical cells C1 to C5). As a result of being able to supply current Im1 and also being able to supply measurement AC current Im2 to the measurement target cells in the second group G2 (in this example, electrochemical cells C10 to C6), it is possible to measure the supply current value (I1, I3) of the measurement AC current Im flowing through the measurement target cells (in this example, electrochemical cells C1 to C5 or electrochemical cells C10 to C6) and the voltage values ​​V1 to V4 of the voltages 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 C10).

[0091] Furthermore, in this impedance measuring device 1 and impedance measuring method, almost none of the measurement AC currents Im1 and Im2 are shunted to the power supply device PD, which results in a large current value I1 of the measurement AC current Im1 shunted to the electrochemical cells C1-C5, which are the measurement target cells, and a large current value I3 of the measurement AC current Im2 shunted to the electrochemical cells C10-C6, which are the measurement target cells. As a result, the voltage value V across each of the electrochemical cells C1-C10 increases. As a result, this impedance measuring device 1 and impedance measuring method can sufficiently increase the ratio (S / N) of the signal level (S) of the measurement AC currents Im1 and Im2 to the noise level (N) of the measured voltage V, thereby enabling the impedance of the measurement target cell to be measured with sufficiently high accuracy.

[0092] Furthermore, according to this impedance measuring device 1 and impedance measuring method, the power supply device PD is not the object of measurement, and the electrolytic device is the DUT to be measured, and some (in this example, any of electrochemical cells C1 to C3, C4, C5, C10 to C6) or all (in this example, all of electrochemical cells C1 to C10) of the multiple electrochemical cells C1 to C10 in the electrolytic device are used as the cells to be measured to measure impedance, thereby making it possible to reliably measure the impedance of the cells to be measured (in this example, electrochemical cells C1 to C10) when the power supply device PD, which has an extremely small output impedance, is connected in parallel to the DUT to be measured.

[0093] Furthermore, in this impedance measuring device 1 and impedance measuring method, the impedances of all electrochemical cells C1-C5 in the first group G1 are taken as measurement target cells and calculated, and the impedances of all electrochemical cells C10-C6 in the second group G2 are taken as measurement target cells and calculated, and the sum of the calculated impedances of all electrochemical cells C1-C5 in the first group G1 and the calculated impedances of all electrochemical cells C10-C6 in the second group G2 is calculated as the impedance of the measurement target DUT. Therefore, with this impedance measuring device 1 and impedance measuring method, the impedance of the measurement target DUT can be measured by a single impedance measurement.

[0094] Furthermore, according to this impedance measuring device 1 and impedance measuring method, the first current value and the second current value are measured using a clamp-type non-contact current sensor that is configured to be openable and closable, so that the first current sensor and the second current sensor can be attached to any position on the DUT to be measured.

[0095] Furthermore, according to this impedance measuring device 1, the current sensor 4-1 is disposed at a position between the measurement current supply point Ps1 and the electrochemical cell C1 in the first group G1, and the current sensor 4-2 is disposed at a position between the measurement current supply point Ps3 and the electrochemical cell C10 in the second group G2. The processing unit 5 calculates the impedances of the electrochemical cells C1 to C5 using the current value I1 of the measurement AC current Im1 as the supply current value flowing through the electrochemical cells C1 to C5 in the first group G1, and calculates the impedances of the electrochemical cells C10 to C6 using the current value I3 of the measurement AC current Im2 as the supply current value flowing through the electrochemical cells C10 to C6 in the second group G2. This makes it possible to calculate the impedances of the cells to be measured by using the supply current values ​​(current values ​​I1 and I3 in this example) measured by the current sensors 4-1 and 4-2 as the current values ​​of the measurement AC current Im flowing through the cells to be measured (electrochemical cells C1 to C5 and electrochemical cells C10 to C6 in this example).

[0096] Furthermore, in this impedance measuring device 1 and impedance measuring method, a position (in this example, the connection point of electrochemical cells C5, C6) where the difference between the number of electrochemical cells C1 to C5 in the first group G1 and the number of electrochemical cells C10 to C6 in the second group G2 is within a value of 1 is set as the measurement current supply point Ps2, and measurement AC currents Im1 and Im2 are supplied, respectively. Therefore, in the impedance measuring device 1 and the impedance measuring method, the current value (I2) of the measurement AC current Im1 flowing through the power supply device PD (current path IR2) and the current value (I4) of the measurement AC current Im2 flowing through the power supply device PD (current path IR4) can be made sufficiently equal, and as a result, the current values ​​of the measurement AC currents Im1 and Im2 flowing through the power supply device PD can be sufficiently offset and reduced. This makes it possible to increase the current value of the measurement AC current Im1 flowing through the measurement target cells (electrochemical cells C1 to C5) and the current value of the measurement AC current Im2 flowing through the measurement target cells (electrochemical cells C10 to C6). In addition, the current value (I1, I3) of the measurement AC current Im measured by the current sensors 4-1 and 4-2 of the measurement AC current Im flowing through the power supply device PD, which is included in the current value, can be sufficiently reduced. As a result, the impedance of the measurement target cell can be measured with sufficiently high accuracy.

[0097] Furthermore, according to this impedance measuring device 1 and impedance measuring method, the frequency characteristics of the impedance of the measurement target cell (in this example, electrochemical cells C1 to C10) at multiple frequencies can be obtained, thereby making it possible to determine the performance and deterioration of the measurement target cell.

[0098] 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.

[0099] Furthermore, according to this impedance measuring device 1 and impedance measuring method, by acquiring either a Cole-Cole plot or a Bode plot as the frequency characteristics, it is possible to determine the performance and degradation of the cell under measurement or the DUT under measurement with high accuracy.

[0100] Furthermore, according to this impedance measuring device 1, when the phase value of the calculated impedance of the cell to be measured is not within the range of -90° to +90°, the processing unit 5 notifies the user of the impedance measuring device 1 that there is an error in the calculated impedance value or that there is an error in the wiring of the current sensors 4-1 and 4-2, thereby making it possible to inform the user of the impedance measuring device 1 that there is an error in the measured (calculated) impedance value or that there is an error in the wiring of the current sensors 4-1 and 4-2, and as a result, it is possible to prompt the user to correctly rewire the current sensors 4-1 and 4-2.

[0101] Furthermore, according to this impedance measuring device 1, when the phase value of the calculated impedance of the measurement target cells (C1 to C3, C4, C5, C10 to C6) is not within the range of -90° to +90°, the processing unit 5 swaps the current value data Di1 (current value I1) and the current value data Di2 (current value I3) to calculate the impedance of the measurement target cells (C1 to C3, C4, C5, C10 to C6), thereby making it possible to correctly measure (calculate) the impedance of the measurement target cells (C1 to C3, C4, C5, C10 to C6) and the measurement target DUT.

[0102] (Second Example) Next, the impedance measuring apparatus 1A will be described with reference to Fig. 3. Note that duplicated descriptions of components and operations similar to those of the impedance measuring apparatus 1 will be omitted.

[0103] The impedance measuring device 1A is configured differently from the impedance measuring device 1 in the position where the current sensor 4-2 is disposed.

[0104] In this impedance measuring device 1A, current sensor 4-2 is disposed at a position between measurement current supply point Ps2 (second measurement current supply point) and the other output portion of each of measurement current output portions 2-1 and 2-2. Therefore, current sensor 4-2 measures a current value (I1+I3) obtained by adding together current value I1 of measurement AC current Im1 flowing through current path IR1 in impedance measuring device 1 (the same current path in impedance measuring device 1A) and current value I3 of measurement AC current Im2 flowing through current path IR3 (the same current path in impedance measuring device 1A), and outputs current value data Di3 (hereinafter, when the current value data Di1 to Di3 are not distinguished from each other) indicating the measured current value (I1+I3: second current value for calculating the supply current value of the measurement AC current flowing through the impedance elements in second group G2) to processing portion 5.

[0105] Furthermore, the processing unit 5 calculates the current value (I3) by subtracting the current value (I1) measured by the current sensor 4-1 from the current value (I1+I3) measured by the current sensor 4-2. In this case, the current value (I3) is the current value of the measurement AC current Im2 flowing through the electrochemical cells C10 to C6 to be measured. Therefore, similar to the impedance measurement process by the impedance measurement device 1 described above, the processing unit 5 calculates the AC voltages across each of the electrochemical cells C1 to C3, C4, C5, and C10 to C6 as the respective voltage values ​​(V) based on the amplitudes of the AC voltages included in the voltage value data Dv1 to Dv4. Furthermore, based on the corrected current value data Di and voltage value data Dv, the processing unit 5 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-C3, C4, C5, C10-C6 that are the measurement target cells and each of the AC voltages generated across both ends of each of the electrochemical cells C1-C3, C4, C5, C10-C6 that are the measurement target cells. Based on the current value (I), voltage value (V), and phase difference (θ) calculated in this way, the processing unit 5 measures (calculates) the impedance (impedance Z=V / I, R=Z cos θ, X=Z sin θ) of each of the electrochemical cells C1-C3, C4, C5, C10-C6 that are the measurement target cells.

[0106] According to this impedance measuring device 1A, the current sensor 4-1 is disposed at a position between the measurement current supply point Ps1 and the electrochemical cell C1 in the first group G1, and the current sensor 4-2 is disposed at a position between the measurement current supply point Ps2 and the output units of the measurement current output units 2-1 and 2-2. The processing unit 5 calculates the impedances of the electrochemical cells C1 to C5 using the current value I1 of the measurement AC current Im1 as the supply current value flowing through the electrochemical cells C1 to C5 in the first group G1, and also calculates the impedances of the electrochemical cells C1 to C5 using the current sensor 4-1. The current value I3 of the measurement AC current Im2 is obtained by subtracting the current value (I1) measured by current sensor 4-1 from the current value (I1+I3) measured by current sensor 4-2, and is used as the supply current value flowing through the electrochemical cells C10 to C6 in the second group G2 to calculate the impedance of the electrochemical cells C10 to C6, thereby calculating the current value of the measurement AC current Im flowing through the cells to be measured (in this example, electrochemical cells C1 to C5 and electrochemical cells C10 to C6).

[0107] (Third Example) Next, the impedance measuring apparatus 1B will be described with reference to Fig. 4. Note that duplicated descriptions of components and operations similar to those of the impedance measuring apparatus 1 will be omitted.

[0108] In this impedance measuring device 1B, a probe Pi2 is connected to the other output part of the measurement current output part 2-1, and a probe Pi4 is connected to the other output part of the measurement current output part 2-2. Also, a current sensor 4-2 is disposed at a position between a measurement current supply point Ps2 (second measurement current supply point) and the other output part of the measurement current output part 2-2.

[0109] In this impedance measuring device 1B, when starting impedance measurement, probe Pi1 is brought into contact with measurement current supply point Ps1, probe Pi2 is brought into contact with measurement current supply point Ps2, probe Pi3 is brought into contact with measurement current supply point Ps3, and probe Pi4 is brought into contact with measurement current supply point Ps2.

[0110] In this state, the current sensor 4-2 measures the current value (I3) of the current value I3 of the measurement AC current Im2 flowing through the current path IR3 in the impedance measuring device 1 (the same current path in the impedance measuring device 1B), and outputs current value data Di4 indicating the measured current value (I3) to the processing unit 5.

[0111] In addition, the processing unit 5 measures (calculates) the impedances (impedance Z=V / I, R=Z·cosθ, X=Z·sinθ) of the electrochemical cells C1 to C3, C4, C5, C10 to C6, which are the cells to be measured, based on the current value (I), voltage value (V), and phase difference (θ) calculated in the same manner as in the impedance measurement process by the impedance measuring device 1 described above.

[0112] According to this impedance measuring device 1B, similarly to the impedance measuring device 1, the supply current values ​​(in this example, current values ​​I1, I3) measured by the current sensors 4-1, 4-2 can be used as the current values ​​of the measurement AC current Im flowing through the cells to be measured (in this example, electrochemical cells C1 to C5, electrochemical cells C10 to C6) to calculate the impedance of the cells to be measured.

[0113] (Fourth Example) Next, an impedance measuring apparatus 1C will be described with reference to Fig. 5. Note that duplicated descriptions of components and operations similar to those of the impedance measuring apparatus 1 will be omitted.

[0114] In this impedance measuring device 1C, the measurement current output units 2-1 and 2-2 are configured as electronic loads. In this case, the measurement current output units 2-1 and 2-2 configure a series circuit in which the negative terminal (the other output terminal) of the measurement current output unit 2-1 is connected to the positive terminal (one output terminal) of the measurement current output unit 2-2. The positive terminal (one output terminal) of the measurement current output unit 2-1 is connected to the positive terminal of the power supply device PD via the measurement current supply line Li, the measurement current supply point Ps1, the terminal T1, the connection point Pc1, and the power supply line Lp, and the negative terminal (the other output terminal) of the measurement current output unit 2-2 is connected to the negative terminal of the power supply device PD via the measurement current supply line Li, the measurement current supply point Ps3, the terminal T11, the connection point Pc2, and the power supply line Lp.

[0115] In this impedance measuring device 1C, at the start of impedance measurement, the processing unit 5 outputs a frequency control signal Sf1 to the measurement current output unit 2-1 to operate the measurement current output unit 2-1 as an AC load, and outputs a frequency control signal Sf2 to the measurement current output unit 2-2 to operate the measurement current output unit 2-2 as an AC load. At this time, the measurement current output unit 2-1 consumes DC power output from the power supply device PD as a load in accordance with the frequency control signal Sf1, thereby supplying a measurement AC current Im1 of the specified frequency to the cell under measurement. Furthermore, the measurement current output unit 2-1 consumes DC power output from the power supply device PD as a load in accordance with the frequency control signal Sf2, thereby supplying a measurement AC current Im2 to the cell under measurement, the amplitude and frequency of which are synchronized with those of the measurement AC current Im1 and the phase of which is 180° opposite to that of the measurement AC current Im1.

[0116] In this state, similarly to the impedance measuring device 1, the current value (I2) of the measurement AC current Im1 flowing through the power supply device PD (current path IR2) and the current value (I4) of the measurement AC current Im2 flowing through the power supply device PD (current path IR4) can be made sufficiently equal. As a result, the current values ​​of the measurement AC currents Im1 and Im2 flowing through the power supply device PD can be sufficiently offset and reduced. This increases the current value of the measurement AC current Im1 flowing through the measurement target cells (electrochemical cells C1 to C5) and the current value of the measurement AC current Im2 flowing through the measurement target cells (electrochemical cells C10 to C6). Furthermore, the current value (I1, I3) of the measurement AC current Im measured by the current sensors 4-1 and 4-2 of the measurement AC current Im flowing through the power supply device PD, which is included in the current value, can be sufficiently reduced. As a result, the impedance of the measurement target cell can be measured with sufficiently high accuracy.

[0117] In addition, the processing unit 5 measures (calculates) the impedances (impedance Z=V / I, R=Z·cosθ, X=Z·sinθ) of the electrochemical cells C1 to C3, C4, C5, C10 to C6, which are the cells to be measured, based on the current value (I), voltage value (V), and phase difference (θ) calculated in the same manner as in the impedance measurement process by the impedance measuring device 1 described above.

[0118] In this impedance measuring device 1C, the measurement current output units 2-1 and 2-2 are configured as electronic loads, and therefore the measurement AC currents Im1 and Im2 are generated by consuming the DC power output from the power supply device PD, making it possible to generate large measurement AC currents Im1 and Im2. Therefore, with this impedance measuring device 1C, the calculated current value (I) and voltage value (V) can be made large, making it possible to measure (calculate) the impedance of the measurement target cell with high accuracy.

[0119] The present invention is not limited to the above-described embodiment and can be modified as appropriate. For example, in the above-described embodiment, four voltage measurement units are used to measure four voltages (voltages across electrochemical cells C1 to C3, voltages across electrochemical cell C4, voltages across electrochemical cell C5, and voltages across electrochemical cells C10 to C6) in one impedance measurement, thereby measuring the impedances of four groups of measurement target cells (electrochemical cells C1 to C3, C4, C5, and C10 to C6). However, the present invention is not limited to this. For example, by using N (N is an integer greater than or equal to 1 and less than the number of cells in the DUT under measurement) voltage measurement units 3 to measure the AC voltages of N groups, it is possible to measure the impedances of N specific electrochemical cells C as measurement target cells. In this case, in the above example, it is possible to measure the impedances of any number of electrochemical cells C in either the first group G1 or the second group G2, that is, the electrochemical cells C1 to C5 in the first group G1 or the electrochemical cells C10 to C6 in the second group G2.

[0120] Furthermore, when it is necessary to measure only the impedance of the DUT under measurement (all of the electrochemical cells C1 to C10), the impedance of the electrochemical cells C1 to C5 as a whole may be measured by using one voltage measurement unit 3, and the impedance of the electrochemical cells C10 to C6 as a whole may be measured by using another voltage measurement unit 3. The sum of the measured impedances may then be calculated as the impedance of the DUT under measurement. Furthermore, the voltage values ​​of the voltages across multiple electrochemical cells C belonging to the first group G1 or the second group G2 out of the 10 electrochemical cells C may be measured using one voltage measurement unit 3, thereby measuring the impedance of the multiple electrochemical cells C belonging to either one of the groups.

[0121] Although the example using two current sensors 4-1 and 4-2 has been described, it is also possible to measure impedance using only one current sensor 4-1 without using current sensor 4-2. In this case, current sensor 4-1 is a clamp-type non-contact current sensor that is configured to be openable and closable. Therefore, by opening and removing current sensor 4-1 and clamping it in place of current sensor 4-2, the impedances of the electrochemical cells C in the first group G1 and the second group G2 can be measured separately.

[0122] Although the example in which the current sensor 4 outputs the current value data Di has been described, it is also possible to adopt a configuration in which the current sensor 4 outputs a current measurement signal that is an analog signal, and the processing unit 5 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 3 outputs a voltage measurement signal that is an analog signal, and the processing unit 5 measures (calculates) the impedance based on the input voltage measurement signal.

[0123] 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.

[0124] Furthermore, in the above embodiment, an example was described in which the impedance of the measurement target cells is measured most accurately by connecting the measurement current supply point Ps2 to the terminal T6 of the measurement target DUT, and the difference between the number of electrochemical cells C1 to C5 belonging to the first group G1 and the number of electrochemical cells C10 to C6 belonging to the second group G2 is set to 0. However, this is not limiting. For example, when the number of electrochemical cells C in the measurement target DUT is even, it is preferable to set the difference between the number of electrochemical cells C belonging to the first group G1 and the number of electrochemical cells C belonging to the second group G2 to 0. However, when the number of electrochemical cells C in the measurement target DUT is odd, it is preferable to set the difference between the number of electrochemical cells C belonging to the first group G1 and the number of electrochemical cells C belonging to the second group G2 to 1.

[0125] Furthermore, when priority is given to being able to measure the impedance itself even if the accuracy of the impedance measurement is somewhat reduced, the measurement current supply point Ps2 can be defined at the connection point between any two of the multiple electrochemical cells C connected in series. In other words, the measurement current supply point Ps2 can be defined at the connection point between the electrochemical cells C, C where the difference between the number of electrochemical cells C belonging to the first group G1 and the number of electrochemical cells C belonging to the second group G2 exceeds 1. In this case, when the measurement current supply point Ps2 is defined in this manner, the difference between the magnitude of the impedance of the current path IR2 relative to the measurement AC current Im1 and the magnitude of the impedance of the current path IR4 relative to the measurement AC current Im2 increases in accordance with the difference between the number of electrochemical cells C included in the current path IR2 and the number of electrochemical cells C included in the current path IR4. Therefore, the amplitude of the measurement AC current Im flowing through the power supply device PD increases. In this state, the current value (I1) measured by the current sensor 4-1 includes the current value of the measurement AC current Im2 flowing through the power supply device PD, and the current value (I3) measured by the current sensor 4-2 includes the current value of the measurement AC current Im1 flowing through the power supply device PD. This causes a measurement error in the impedance measurement process by the processing unit 5. Therefore, it is preferable to define the measurement current supply point Ps2 at a position where the difference between the number of electrochemical cells C belonging to the first group G1 and the number of electrochemical cells C belonging to the second group G2 is 1.

[0126] In the above examples, an electrolytic device was used as the DUT to be measured, but other DUTs may 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). [Industrial Applicability]

[0127] According to the present invention, even when a low-impedance non-measurement object is connected in parallel to the measurement object, it is possible to measure the supply current value of the measurement AC current flowing through the measurement object impedance element and the voltage value across the measurement object impedance element when the measurement AC current is supplied to the measurement object impedance element, thereby making it possible to reliably measure the impedance of the measurement object impedance element. As a result, the present invention can be widely applied to impedance measurement devices and impedance measurement methods for such impedance measurements. [Explanation of symbols]

[0128] 1 1A~1C Impedance measuring device 2-1, 2-2 Measurement current output section 3-1~3-4 Voltage measurement section 4-1, 4-2 Current sensor 5 Processing section C1~C10 Electrochemical Cells Di1~Di4 current value data DUT Measurement target Dv1~Dv4 voltage value data Lc connection line Li measurement current supply line Pc1,Pc2 connection point PD power supply Ps1~Ps3 Measured current supply point

Claims

1. a measurement current supply unit that supplies a measurement AC current to an impedance element to be measured among a plurality of impedance elements connected in series between a pair of terminals, in a state in which an object to be measured is connected in parallel to the impedance element to be measured; a current detection unit for measuring a supply current value of the measurement AC current supplied to the impedance element to be measured; a voltage measurement unit for measuring a voltage value of a voltage across both ends of the impedance element to be measured; a processing unit that calculates the impedance of the impedance element to be measured based on the measured supply current value and the voltage value of the voltage across the two ends, the measurement current supply unit is configured to include a first current supply unit and a second current supply unit; the first current supply unit supplies, as the measurement AC current, a first measurement current to the impedance elements in a first group located between a first measurement current supply point defined on the side of one of the pair of terminals and a second measurement current supply point defined at a connection point of any two of the plurality of impedance elements connected in series; the second current supply unit supplies, as the measurement AC current, to the impedance elements in the second group located between a third measurement current supply point defined on the other terminal side of the pair of terminals and the second measurement current supply point, a second measurement current whose amplitude, frequency and phase are synchronized with those of the first measurement current so that the first measurement current and the first measurement current cancel each other out and the amplitude of the measurement AC current flowing through the non-measurement object becomes smaller; the current detection unit is configured to include a first current sensor and a second current sensor, the first current sensor measures a first current value for calculating a supply current value of the measurement AC current flowing through the impedance elements in the first group; the second current sensor measures a second current value for calculating a supply current value of the measurement AC current flowing through the impedance elements in the second group; the voltage measurement unit is configured to include a first measurement circuit and a second measurement circuit; the first measurement circuit measures a first voltage value of an AC voltage occurring across the impedance element to be measured in the first group; the second measurement circuit measures a second voltage value of an AC voltage occurring across both ends of the impedance element to be measured in the second group; The processing unit calculates the impedance of the impedance element to be measured in the first group based on the first current value measured by the first current sensor and the first voltage value measured by the first measurement circuit, and calculates the impedance of the impedance element to be measured in the second group based on the second current value measured by the second current sensor and the second voltage value measured by the second measurement circuit.

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

3. 2. The impedance measuring device of claim 1, wherein the processing unit calculates the impedance of all impedance elements in the first group as the impedance elements to be measured, and calculates the impedance of all impedance elements in the second group as the impedance elements to be measured, and calculates the sum of the calculated impedances of all impedance elements to be measured in the first group and the calculated impedances of all impedance elements to be measured in the second group as the impedance of the object to be measured.

4. 2. The impedance measuring device according to claim 1, wherein the first current sensor and the second current sensor are configured as openable and closable clamp-type non-contact current sensors.

5. the first current sensor is disposed at a position between the first measurement current supply point and the impedance element in the first group; the second current sensor is disposed at one of a position between the third measurement current supply point and the impedance element in the second group and a position between the second measurement current supply point and an output of the second current supply unit; 2. The impedance measuring device according to claim 1, wherein the processing unit calculates the impedance of the impedance element to be measured using the first current value as a supply current value flowing through the impedance element to be measured in the first group, and calculates the impedance of the impedance element to be measured using the second current value as a supply current value flowing through the impedance element to be measured in the second group.

6. the first current sensor is disposed at a position between the first measurement current supply point and the impedance element in the first group; a second current sensor is disposed at a position between the second measurement current supply point and each output of the first current supply and the second current supply; 2. The impedance measuring device according to claim 1, wherein the processing unit calculates the impedance of the impedance element to be measured by using the first current value as the supply current value flowing through the impedance element to be measured in the first group, and calculates the impedance of the impedance element to be measured by using the current value obtained by subtracting the first current value from the second current value as the supply current value flowing through the impedance element to be measured in the second group.

7. The impedance measuring device of claim 1, wherein the first current supply unit and the second current supply unit supply the first measurement current and the second measurement current, respectively, at a position where the difference between the number of impedance elements in the first group and the number of impedance elements in the second group is within a value of 1 as the second measurement current supply point.

8. 2. The impedance measuring device according to claim 1, wherein the first current supply unit and the second current supply unit are configured as electronic loads.

9. the first measurement current supply unit and the second measurement current supply unit are each configured to be able to vary the frequency of the measurement AC current in accordance with a frequency control signal; 2. The impedance measuring device according to claim 1, wherein the processing unit outputs the frequency control signal to the first measurement current supply unit and the second measurement current supply unit to vary the frequency of the measurement AC current, thereby acquiring frequency characteristics of the impedance of the measurement target impedance element at a plurality of frequencies.

10. 10. The impedance measuring device according to claim 9, 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.

11. 11. The impedance measuring device according to claim 9, wherein the processing unit acquires either a Cole-Cole plot or a Bode diagram as the frequency characteristics.

12. The impedance measuring device of claim 1, wherein the processing unit notifies that there is an error in the calculated impedance value or that there is an error in the wiring of the first current sensor and the second current sensor when the phase value of the calculated impedance of the impedance element to be measured is not within the range of -90° to +90°.

13. 2. The impedance measuring device according to claim 1, wherein when the phase value of the calculated impedance of the impedance element to be measured is not within a range of −90° to +90°, the processing unit swaps the first current value and the second current value to calculate the impedance of the impedance element to be measured.

14. In a state where a measurement object is configured to include a plurality of impedance elements connected in series between a pair of terminals and a non-measurement object is connected in parallel to the measurement object, a measurement AC current is supplied to the measurement object impedance element among the plurality of impedance elements, Measure the supply current value of the measurement AC current supplied to the measurement target impedance element; Measure the voltage value of the voltage across both ends of the impedance element to be measured; An impedance measurement method for calculating an impedance of the impedance element to be measured based on the measured supply current value and the voltage value of the voltage across the two ends, supplying a first measurement current as the measurement AC current to the impedance elements in a first group located between a first measurement current supply point defined on the side of one of the pair of terminals and a second measurement current supply point defined at a connection point between any two of the plurality of impedance elements connected in series; supplying, as the measurement AC current, a second measurement current whose amplitude, frequency and phase are synchronized with those of the first measurement current to the impedance elements in the second group located between a third measurement current supply point defined on the other terminal of the pair of terminals and the second measurement current supply point so that the second measurement current and the first measurement current cancel each other out and the amplitude of the measurement AC current flowing through the non-measurement object becomes smaller; measuring a first current value for calculating a supply current value of the measurement AC current flowing through the impedance elements in the first group; measuring a second current value for calculating a supply current value of the measurement AC current flowing through the impedance elements in the second group; measuring a first voltage value of an AC voltage occurring across both ends of the impedance element to be measured in the first group; measuring a second voltage value of the AC voltage occurring across both ends of the impedance element to be measured in the second group; An impedance measurement method that calculates the impedance of the impedance element to be measured in the first group based on the measured first current value and the measured first voltage value, and calculates the impedance of the impedance element to be measured in the second group based on the measured second current value and the measured second voltage value.

15. 15. The impedance measurement method according to claim 14, wherein a power supply device is set as the non-measurement object, and either an electrolysis device or an electrolysis-reduction device having a plurality of impedance elements is set as the measurement object, and the impedance is measured using some or all of the plurality of impedance elements as the measurement object impedance elements.

16. An impedance measurement method according to claim 14, wherein the impedance of all impedance elements in the first group is calculated as the impedance elements to be measured, and the impedance of all impedance elements in the second group is calculated as the impedance elements to be measured, and the sum of the calculated impedances of all impedance elements to be measured in the first group and the calculated impedances of all impedance elements to be measured in the second group is calculated as the impedance of the object to be measured.

17. 15. The impedance measuring method according to claim 14, wherein the first current value and the second current value are measured using a clamp-type non-contact current sensor that is configured to be able to open and close.

18. The impedance measurement method according to claim 14, wherein the first measurement current and the second measurement current are respectively supplied at the second measurement current supply point at a position where the difference between the number of impedance elements in the first group and the number of impedance elements in the second group is within a value of 1.

19. The impedance measuring method according to claim 14, further comprising acquiring frequency characteristics of the impedance of the impedance element to be measured at a plurality of frequencies.

20. The impedance measuring method according to claim 19, wherein the frequency characteristics of the impedance of the measurement object are obtained based on the frequency characteristics of the impedance of the impedance element to be measured.

21. 21. The impedance measuring method according to claim 19, wherein one of a Cole-Cole plot and a Bode diagram is obtained as the frequency characteristics.

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