Impedance measuring apparatus and impedance measuring method

Abstract

To measure the impedance of an impedance element in a state where a measuring object constituted by connecting a plurality of impedance elements in series and a non-measuring object are connected in parallel.SOLUTION: A measuring current supplying unit 2-1 configured to supply a measuring AC current C2 between both ends of the electrochemical cells C3 and Im1, a measuring current supplying unit 2-2 configured to supply a measuring AC current C7 between both ends of the electrochemical cells Im2 to C10, a voltage detecting unit 3-1 configured to detect complex both-end voltage values C2 at both ends of the electrochemical cells C3 and, and a processing unit 4 configured to calculate impedances of the electrochemical cells and V1 based on complex current values of the measuring AC current outputted from the measuring current supplying unit 2-1, complex current values IL of an AC current Iac flowing through the power supply device PD, and the complex both-end voltage values detected by the voltage detecting unit 3-1. Im1 V1 C3 C2.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 in a state where a measurement target configured by connecting a plurality of impedance elements in series and a non-measurement target are connected in parallel 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 an impedance element when a measurement object configured by connecting multiple impedance elements in series and a non-measurement object are connected in parallel via a connection line. [Means for solving the problem]

[0008] In order to achieve the above object, the impedance measuring device according to the present invention is an impedance measuring device that measures the impedance of an impedance element in a state in which a measurement object configured by connecting a plurality of impedance elements in series between one end and the other end and a non-measurement object are connected in parallel via a connection line, and includes a first measurement current supply unit that supplies a first measurement AC current between both ends of some of the plurality of impedance elements that are located between the one end and an intermediate portion, and a second measurement current supply unit that supplies a first measurement AC current between both ends of other of the plurality of impedance elements that are located between the other end and the intermediate portion, the first measurement AC current and the second measurement current being adjusted to have a frequency, amplitude and phase such that the first measurement AC current cancels out each other and the amplitude of the AC current flowing through the non-measurement object becomes small. The measurement device includes a second measurement current supply unit that supplies a second measurement AC current synchronized with the first measurement AC current; a first voltage detection unit that detects a complex voltage value across both ends of a first measurement target impedance element among the certain impedance elements in a measurement AC current supply state in which the first measurement AC current is supplied across the certain impedance elements and the second measurement AC current is supplied across the certain other impedance elements; and a processing unit that calculates the impedance of the first measurement target impedance element based on the complex current value of the first measurement AC current output from the first measurement current supply unit in the measurement AC current supply state, the complex current value of the AC current flowing through the non-measurement target, and the complex voltage value detected by the first voltage detection unit.

[0009] Furthermore, in order to achieve the above object, an impedance measurement method according to the present invention is an impedance measurement method for measuring the impedance of an impedance element in a state in which a measurement object configured by connecting a plurality of impedance elements in series between one end and the other end and a non-measurement object are connected in parallel via a connection line, the method comprising: supplying a first measurement AC current between both ends of some of the plurality of impedance elements that are located between the one end and an intermediate portion; and supplying a first measurement AC current between both ends of other of the plurality of impedance elements that are located between the other end and the intermediate portion so that the first measurement AC current and the AC current flowing through the non-measurement object cancel each other out and the amplitude of the AC current flowing through the non-measurement object becomes small. a second measurement AC current whose amplitude and phase are synchronized with those of the first measurement AC current; and in a measurement AC current supply state in which the first measurement AC current is supplied between the two ends of the partial impedance elements and the second measurement AC current is supplied between the two ends of the other partial impedance elements, a complex voltage value across both ends of a first impedance element to be measured among the partial impedance elements is detected; and the impedance of the first impedance element to be measured is measured based on the complex current value of the first measurement AC current output from the first measurement current supply unit in the measurement AC current supply state, the complex current value of the AC current flowing through the non-measurement element, and the complex voltage value detected by the first voltage detection unit.

[0010] According to this impedance measuring device and impedance measuring method, even when the impedance of a non-measurement object connected in parallel to the measurement object via the measurement current supply line is extremely small, the first measurement AC current can be supplied to the first measurement object impedance element, making it possible to measure the complex current value of the AC current flowing through the first measurement object impedance element and the complex end-to-end voltage value of the first measurement object impedance element when the first measurement AC current is supplied to the first measurement object impedance element, thereby enabling the impedance of the first measurement object impedance element to be reliably measured.

[0011] Furthermore, the impedance measuring device according to the present invention includes a first current detection unit that detects a complex current value of an AC current flowing through the non-measurement object, and when the direction of the AC current detected by the first current detection unit is toward the other end of the measurement object, the processing unit calculates the impedance of the first measurement object impedance element based on a complex current value obtained by subtracting the complex current value of the AC current detected by the first current detection unit from the complex current value of the first measurement AC current output from the first measurement current supply unit, and on the complex end-to-end voltage value detected by the first voltage detection unit.

[0012] Furthermore, the impedance measurement method according to the present invention detects a complex current value of an AC current flowing through the non-measurement object, and when the direction of the detected AC current is toward the other end of the measurement object, measures the impedance of the first measurement object impedance element based on a complex current value obtained by subtracting the complex current value of the detected AC current from the complex current value of the first measurement AC current, and the detected complex end-to-end voltage value.

[0013] Furthermore, the impedance measuring device according to the present invention includes a first current detection unit that detects a complex current value of the AC current flowing through the non-measurement object, and when the direction of the AC current detected by the first current detection unit is toward the one end of the measurement object, the processing unit calculates the impedance of the first measurement object impedance element based on a complex current value obtained by adding the complex current value of the first measurement AC current output from the first measurement current supply unit and the complex current value of the AC current detected by the first current detection unit, and on the complex end-to-end voltage value detected by the first voltage detection unit.

[0014] Furthermore, the impedance measurement method according to the present invention detects a complex current value of an AC current flowing through the non-measurement object, and when the direction of the detected AC current is toward the one end of the measurement object, measures the impedance of the first measurement object impedance element based on a complex current value obtained by adding the complex current value of the first measurement AC current and the complex current value of the detected AC current, and the detected complex end-to-end voltage value.

[0015] According to this impedance measuring device and impedance measuring method, the complex current value of the AC current flowing through the non-measurement target can actually be detected, and therefore the complex current value of the AC current flowing through the first measurement target impedance element can be measured (calculated) more accurately, and as a result, the impedance of the first measurement target impedance element can be measured (calculated) more accurately.

[0016] The impedance measuring device according to the present invention also includes a second current detection section that detects a complex current value of the first measurement AC current output from the first measurement current supply section.

[0017] Moreover, the impedance measuring method according to the present invention detects a complex current value of the first measurement AC current.

[0018] This impedance measuring device and method can actually measure and grasp the complex current value of the first measurement AC current, and therefore can accurately measure (calculate) the impedance of the first measurement target impedance element.

[0019] Furthermore, the impedance measuring device according to the present invention includes a third current detection unit that detects a complex current value of the second measurement AC current output from the second measurement current supply unit, and a second voltage detection unit that, in the measurement AC current supply state, detects a complex voltage value across both ends of a second impedance element to be measured among the other impedance elements, and the processing unit calculates the impedance of the second impedance element to be measured based on a complex current value obtained by adding together the complex current value of the second measurement AC current output from the second measurement current supply unit detected by the third current detection unit and the complex current value of the AC current detected by the first current detection unit, and on the complex voltage value across both ends detected by the second voltage detection unit.

[0020] Furthermore, the impedance measurement method according to the present invention detects a complex current value of the second measurement AC current, and in the measurement AC current supply state, detects a complex voltage value across both ends of a second impedance element to be measured among the other impedance elements, and measures the impedance of the second impedance element to be measured based on a complex current value obtained by adding the detected complex current value of the second measurement AC current and the detected complex current value of the AC current across the second impedance element to be measured, and the detected complex voltage value across both ends.

[0021] Furthermore, the impedance measuring device according to the present invention includes a third current detection unit that detects a complex current value of the second measurement AC current output from the second measurement current supply unit, and a second voltage detection unit that, in the measurement AC current supply state, detects a complex voltage value across both ends of a second impedance element to be measured among the other impedance elements, and the processing unit calculates the impedance of the second impedance element to be measured based on a complex current value obtained by subtracting the complex current value of the AC current detected by the first current detection unit from the complex current value of the second measurement AC current output from the second measurement current supply unit detected by the third current detection unit, and on the complex voltage value across both ends detected by the second voltage detection unit.

[0022] Furthermore, the impedance measurement method according to the present invention detects a complex current value of the second measurement AC current, and in the measurement AC current supply state, detects a complex voltage value across both ends of a second impedance element to be measured among the other impedance elements, and measures the impedance of the second impedance element to be measured based on a complex current value obtained by subtracting the complex current value of the detected AC current from the complex current value of the detected second measurement AC current, and the detected complex voltage value across both ends of the second impedance element to be measured.

[0023] This impedance measuring device and method can actually measure and grasp the complex current value of the second measurement AC current accurately, and therefore this impedance measuring device and method can accurately measure (calculate) the impedance of the second measurement target impedance element.

[0024] In the impedance measuring device according to the present invention, the first measurement current supply unit and the second measurement current supply unit are configured by electronic loads.

[0025] In the impedance measuring method according to the present invention, the first measurement AC current and the second measurement AC current are supplied from an electronic load.

[0026] This impedance measuring device and impedance measuring method can generate large first and second AC currents for measurement. Therefore, this impedance measuring device and impedance measuring method can increase the complex current value and complex voltage value across the AC current flowing through the first and second impedance elements to be measured, making it possible to accurately measure (calculate) the complex current value of the AC current flowing through the first and second impedance elements to be measured, as well as accurately measure (calculate) the complex voltage value across the AC current, and as a result, it is possible to accurately measure (calculate) the impedance of the first and second impedance elements to be measured, as well as the impedance of the measurement targets.

[0027] In addition, in the impedance measuring device according to the present invention, the impedance measuring device measures the impedance of the impedance element within the measurement object, which is configured by electrically connecting in series impedance elements that cause an electrochemical reaction.

[0028] Furthermore, the impedance measuring method according to the present invention measures the impedance of the impedance element within the measurement object, which is configured by electrically connecting in series impedance elements that cause an electrochemical reaction.

[0029] According to this impedance measuring device and impedance measuring method, the impedance of the impedance element and the object to be measured can be measured with high accuracy while the object to be measured and the object not to be measured are in operation.

[0030] In addition, in the impedance measuring device of the present invention, the first measurement current supply unit is configured to be able to vary the frequency of the first measurement AC current in accordance with a frequency control signal, the second measurement current supply unit is configured to be able to vary the frequency of the second measurement AC current in accordance with a frequency control signal, and the processing unit acquires the frequency characteristics of the impedance of the impedance element by outputting the frequency control signal to the first measurement current supply unit and the second measurement current supply unit to vary the frequencies of the first measurement AC current and the second measurement AC current.

[0031] Moreover, the impedance measuring method according to the present invention varies the frequencies of the first measurement AC current and the second measurement AC current to acquire the frequency characteristics of the impedance of the impedance element.

[0032] According to this impedance measuring device and impedance measuring method, it is possible to determine the performance and degradation state of the first impedance element to be measured, the second impedance element to be measured, and the object to be measured.

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

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

[0035] According to this impedance measuring device and impedance measuring method, the performance and degradation state of an impedance element or an object to be measured can be determined with high accuracy.

[0036] In the impedance measuring device according to the present invention, the processing unit records the acquired frequency characteristics in a recording unit.

[0037] In addition, in the impedance measuring method according to the present invention, the acquired frequency characteristics are recorded in a recording unit.

[0038] According to this impedance measuring device and impedance measuring method, it is possible to realize the function of a recording device. [Effects of the Invention]

[0039] 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 by connecting multiple impedance elements in series, it is possible to measure the complex current value of the AC current flowing through the first measurement object impedance element and the complex end-to-end voltage value at both ends of the first measurement object impedance element when the first measurement object AC current and the second measurement object AC current are supplied to the first measurement object impedance element and the second measurement object impedance element, thereby making it possible to reliably measure the impedance of the first measurement object impedance element. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a diagram showing the configuration of an impedance measuring device 1. FIG. [Figure 2] 10 is an explanatory diagram for explaining the flow paths of measurement AC currents Im1 and Im2 in a measurement AC current supply state. FIG. [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

[0041] 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.

[0042] 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 the impedance elements to be measured by selecting some or all of the impedance elements as the impedance elements to be measured, when a power supply device PD as a non-measurement object is connected in parallel to a DUT to be measured, which is configured by connecting multiple impedance elements in series, via a bus bar Bb as a connection line that functions as a power supply line.

[0043] In this case, the DUT to be measured may include an electrolysis device (electrolysis device) in which multiple electrochemical cells (an example of an impedance element) are electrically connected in series to form a stack; an electrolysis reduction device (electrolytic reduction device) in which multiple electrolyte membranes (an example of an impedance element) are electrically connected in series to form a stack; an ion exchange membrane device in which multiple ion exchange membranes (an example of an impedance element) are electrically connected in series to form a stack; a fuel cell in which multiple power generation cells (an example of an impedance element) are electrically connected in series to form a stack; and a lithium ion battery or lead-acid battery in which multiple battery cells (an example of an impedance element) are electrically connected in series to form a stack. Non-measurement targets may include power supply devices such as inverters and converters, various loads such as electronic devices, and various power generation devices such as operating or non-operating fuel cells. An organic electrolytic reduction device used in the production of MCH (methylcyclohexane), a hydrogen carrier, is known as an electrolytic reduction device (see JP 2022-30943 A).

[0044] However, the impedance measuring device 1 is not limited to this, and is configured to be suitable for accurately measuring the impedance of an impedance element in a DUT under test when a large DC current flows through the bus bar Bb, forming an active line. As an example, the following describes an example in which an electrolytic device is the DUT under test and a power supply device PD that supplies power to drive the DUT under test is not the object of measurement.

[0045] First, the DUT under test will be described. As shown in FIG. 1, in this example, the DUT under test is an electrolysis device configured by electrically connecting multiple electrochemical cells C1 to C10 (hereinafter, referred to as "electrochemical cells C" when not distinguished) in series to form a stack. While an electrolysis device is actually configured by connecting several tens to several hundreds of electrochemical cells C in series, in this example, for ease of understanding, the DUT under test is configured by electrically connecting ten electrochemical cells C1 to C10 in series. In this case, the DUT under test is provided with a pair of input terminals T1 and T11, and terminals T2 to T10 (hereinafter, referred to as "terminals T" when not distinguished) connected to the connection points of the electrochemical cells C, C, respectively. Terminal T1 corresponds to one end of the DUT under test, and terminal T11 corresponds to the other end of the DUT under test. As will be described later, terminal T (terminal T6 in the figure) with which probe Pi3 is in contact corresponds to the middle portion of the DUT under test.

[0046] (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 supply units 2-1 and 2-2, voltage detection units 3-1 and 3-2, processing unit 4, output unit 5, recording unit 6, probes Pi1 to Pi3 for supplying measurement currents, and probes Pv1 to Pv4 for detecting voltages. Note that hereinafter, when there is no need to distinguish between measurement current supply units 2-1 and 2-2, they will also be referred to as "measurement current supply unit 2," when there is no need to distinguish between voltage detection units 3-1 and 3-2, they will also be referred to as "voltage detection unit 3," when there is no need to distinguish between probes Pi1 to Pi3, they will also be referred to as "probe Pi," and when there is no need to distinguish between probes Pv1 to Pv4, they will also be referred to as "probe Pv."

[0047] The measurement current supply unit 2-1 functions as a first measurement current supply unit that supplies a measurement AC current to an electrochemical cell C (hereinafter also referred to as "measurement target electrochemical cell C") as an impedance element to be measured, and generates and outputs a measurement AC current Im1 (first measurement AC current) that is a sinusoidal AC signal for measuring the impedance of the measurement target electrochemical cell C in accordance with instructions from the processing unit 4. In addition, measurement current supply lines Li are connected to one output terminal and the other output terminal of the measurement current supply unit 2-1, respectively. Therefore, the measurement current supply unit 2-1 supplies the measurement AC current Im1 to the measurement target electrochemical cell C via the measurement current supply lines Li, Li and the probes Pi1, Pi3.

[0048] The measurement current supply unit 2-1 is configured to vary the frequency of the measurement AC current Im1 and outputs the frequency of the measurement AC current Im1 by sweeping (changing) it in accordance with a frequency control signal Sf1 output from the processing unit 4. In this case, since the measurement current supply unit 2-1 is a current source, its output impedance is extremely large. The measurement current supply unit 2-1 also supplies the measurement AC current Im1 between both ends of some of the electrochemical cells C located between the terminal T1 (one end) and the intermediate terminal T of the DUT under test. As shown in FIG. 1, for example, when the probe Pi3 is connected to the terminal T6, a first group G1 is formed to include some of the electrochemical cells C1 to C5 located between the terminal T1 (one end) and the intermediate terminal T6. The measurement current supply unit 2-1 supplies the measurement AC current Im1 between both ends of the electrochemical cells C1 to C5 belonging to this first group G1.

[0049] The measurement current supply unit 2-2 functions as a second measurement current supply unit that supplies a measurement AC current to the electrochemical cell C under measurement, which serves as the impedance element under measurement, and generates and outputs a measurement AC current Im2 (second measurement AC current) that is a sinusoidal AC signal for measuring the impedance of the electrochemical cell C under measurement, in accordance with instructions from the processing unit 4. Furthermore, measurement current supply lines Li are connected to one output terminal and the other output terminal of the measurement current supply unit 2-2, respectively. Therefore, the measurement current supply unit 2-2 supplies the measurement AC current Im2 to the electrochemical cell C under measurement via the measurement current supply lines Li, Li and the probes Pi2, Pi3.

[0050] The measurement current supply unit 2-2 is configured to vary the frequency of the measurement AC current Im2 and outputs the measurement AC current Im2 whose frequency, amplitude, and phase are synchronized with those of the measurement AC current Im1 in accordance with the frequency control signal Sf2 output from the processing unit 4. In this case, the measurement current supply unit 2-2 supplies the measurement AC current Im2 whose frequency, amplitude, and phase are synchronized with those of the measurement AC current Im1 in accordance with the frequency control signal Sf2 output from the processing unit 4 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 are reduced, that is, so that the complex current value IL of the AC current Iac consisting of the measurement AC currents Im1 and Im2 flowing through the power supply device PD is reduced. Note that the complex current value refers to a current value including frequency, amplitude, and phase. The measurement current supply unit 2-2 sweeps (changes) the frequency of the measurement AC current Im2 and outputs it in accordance with the frequency control signal Sf2. Furthermore, since the measurement current supply unit 2-2 is a current source, its output impedance is extremely large. Hereinafter, when there is no need to distinguish between the measurement AC currents Im1 and Im2, they will also be referred to as the "measurement AC current Im." The measurement current supply unit 2-2 supplies the measurement AC current Im2 between both ends of some of the electrochemical cells C located between the terminal T11 (the other end) of the DUT under test and the intermediate terminal T. As shown in FIG. 1, for example, when the probe Pi2 is connected to the terminal T6, the group to which some of the electrochemical cells C6 to C10 located between the terminal T11 at the other end and the intermediate terminal T6 belong is defined as a second group G2, and the measurement current supply unit 2-2 supplies the measurement AC current Im2 between both ends of the electrochemical cells C6 to C10 belonging to this second group G2.

[0051] In the impedance measuring device 1 of this example, the other output portion of the measurement current supply unit 2-1 and the other output portion of the measurement current supply unit 2-2 are connected, and the other output portions of both measurement current supply units 2-1 and 2-2 are connected to the probe Pi3 via a single measurement current supply line Li, but this configuration is not limited to this. For example, by connecting separate measurement current supply lines Li to the other output portions of both measurement current supply units 2-1 and 2-2 and connecting separate probes for supplying measurement current to each measurement current supply line Li, the other output portions of both measurement current supply units 2-1 and 2-2 can be connected to the same terminal T or different terminals T of the DUT to be measured.

[0052] The voltage detection unit 3 detects the input voltage via a pair of probes Pv and Pv and outputs voltage value data indicating the detected value to the processing unit 4. As shown in FIG. 1 , the voltage detection unit 3-1 is connected to terminals T and T of the DUT under test via probes Pv1 and Pv2, and the voltage detection unit 3-2 is connected to terminals T and T of the DUT under test via probes Pv3 and Pv4. The voltage detection unit 3-1 functions as a first voltage detection unit and detects a complex voltage value V1 across the electrochemical cell C under test in the first group G1, and the voltage detection unit 3-2 functions as a second voltage detection unit and detects a complex voltage value V2 across the electrochemical cell C under test in the second group G2. In this case, the complex voltage value refers to a voltage value including frequency, amplitude, and phase. Hereinafter, when the complex voltage values ​​V1 and V2 are not distinguished, they are also referred to as the "complex voltage value V."

[0053] Furthermore, the voltage detection unit 3-1 detects a complex voltage value V1 occurring across the probes Pv1 and Pv2 in accordance with instructions from the processing unit 4, and outputs voltage value data Dv1 indicating the detected value to the processing unit 4. Furthermore, the voltage detection unit 3-2 detects a complex voltage value V2 occurring across the probes Pv3 and Pv4 in accordance with instructions from the processing unit 4, and outputs voltage value data Dv2 indicating the detected value to the processing unit 4. Note that hereinafter, when there is no need to distinguish between the voltage value data Dv1 and Dv2, they are also referred to as "voltage value data Dv."

[0054] The processing unit 4 is configured by, for example, a CPU, and performs overall control of the impedance measuring device 1. Specifically, during impedance measurement, the processing unit 4 controls the measurement current supply unit 2 to generate and output a measurement AC current Im. During impedance measurement, the processing unit 4 also controls the voltage detection unit 3 to output voltage value data Dv. During impedance measurement, as will be described later, the processing unit 4 measures (calculates) the impedances of some or all of the electrochemical cells C1 to C5 in the first group G1 as measurement target electrochemical cells C, and also measures (calculates) the impedances of some or all of the electrochemical cells C6 to C10 in the second group G2 as measurement target electrochemical cells C.

[0055] In addition, in accordance with instructions from an operation unit (not shown), the processing unit 4 outputs frequency control signals Sf1 and Sf2 to the measurement current supply units 2-1 and 2-2 to synchronize the frequencies, amplitudes, and phases of the measurement AC currents Im1 and Im2 and sweep them between the low and high frequency bands. The processing unit 4 also outputs display data Dd to the output unit 5 to display the measured impedance of the electrochemical cell C under test, the impedance of the DUT under test as a whole, and frequency characteristics of the impedance such as Cole-Cole plots and Bode plots (described below). The processing unit 5 also outputs measurement data Dm indicating the measured impedance of the electrochemical cell C under test, the impedance of the DUT under test, and frequency characteristics of the impedance such as Cole-Cole plots and Bode plots to the recording unit 6 for recording.

[0056] The output unit 5 is, for example, a display device such as a liquid crystal panel or an organic electroluminescence (EL) panel, and receives the display data Dd output from the processing unit 4 to display the impedance of the electrochemical cell C under test, the impedance of the DUT under test as a whole, and the frequency characteristics of that impedance on a screen. Instead of a display device, the output unit 5 may be configured as an interface device that communicates data with an external device, and output impedance data indicating the impedance of the electrochemical cell C under test, the impedance of the DUT under test as a whole, and the frequency characteristics of that impedance to the external device. The recording unit 6 is, for example, a hard disk, and receives the measurement data Dm output from the processing unit 4 to record the measured impedance of the electrochemical cell C under test, the impedance of the DUT under test, and the frequency characteristics of the impedance, such as a Cole-Cole plot and a Bode plot.

[0057] Probes Pi1 to Pi3 are contact-type probes whose tips are connected (contacted) directly or indirectly to terminals T of the DUT to be measured to supply measurement AC currents Im1 and Im2. Probes Pv1 to Pv4 are contact-type probes whose tips are connected (contacted) directly or indirectly to terminals T of the DUT to be measured to measure complex end-to-end voltages V generated across terminals T and T when measurement AC currents Im1 and Im2 are supplied to the electrochemical cell C to be measured.

[0058] Next, with reference to the drawings, an impedance measurement method will be described in which an arbitrary electrochemical cell C designated by an indicator (not shown) is set as the measurement target electrochemical cell C and its impedance is measured (calculated) using the impedance measurement device 1. It is assumed that the power supply device PD is connected to a pair of terminals T1 and T11 of the measurement target DUT via a bus bar Bb.

[0059] First, probes Pi1 to Pi3 are connected to terminal T of the DUT under test. In this case, probe Pi1 is connected to bus bar Bb connected to terminal T1, which is one end of the DUT under test. Probe Pi3 is connected to bus bar Bb connected to terminal T11, which is the other end of the DUT under test. Probe Pi2 is connected to terminal T, which is the intermediate portion of the DUT under test. In this case, it is preferable to select terminal T6 as the intermediate portion of the DUT under test and connect probe Pi2 to it so that 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. Therefore, five electrochemical cells C1 to C5 belong to the first group G1, and five electrochemical cells C6 to C10 belong to the second group G2. However, in reality, since a large number of electrochemical cells C are stacked in the DUT under measurement, it is preferable to select the terminal T as the middle part of the DUT under measurement so that the number of electrochemical cells C belonging to the first group G1 is approximately equal to the number of electrochemical cells C belonging to the second group G2. Also, by selecting the middle terminal T so that 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 approximately 0 or 1, it becomes possible to accurately measure the impedance of the electrochemical cell C under measurement.

[0060] Further, probes Pv1 to Pv4 are connected to terminal T of the DUT under test. In this case, as an example, some electrochemical cells C2 and C3 of the plurality of electrochemical cells C belonging to the first group G1 are set as the electrochemical cells C under test, and some electrochemical cells C7 to C10 of the plurality of electrochemical cells C belonging to the second group G2 are set as the electrochemical cells C under test. In this case, probe Pv1 is connected to terminal T2 of the DUT under test, probe Pv2 is connected to terminal T4 of the DUT under test, probe Pv3 is connected to terminal T7 of the DUT under test, and probe Pv4 is connected to terminal T11 of the DUT under test. In this case, electrochemical cells C2 and C3 correspond to the first impedance element under test, and electrochemical cells C7 to C10 correspond to the second impedance element under test.

[0061] Next, a measurement start switch (not shown) is operated. This causes the processing unit 4 to output a frequency control signal Sf1 to control the measurement current supply unit 2-1 to output the measurement AC current Im1 as the first measurement AC current, and to output a frequency control signal Sf2 to control the measurement current supply unit 2-2 to output the measurement AC current Im2 as the second measurement AC current. When outputting the frequency control signal Sf2 to the measurement current supply unit 2-2, the processing unit 4 causes the measurement current supply unit 2-2 to output the measurement AC current Im2 whose frequency, amplitude, and phase are synchronized with those of the measurement AC current Im1 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 other words, the complex current value IL of the AC current Iac flowing through the power supply device PD becomes smaller. Therefore, the complex current values, which are current values ​​including the frequency, amplitude, and phase of the measurement AC currents Im1 and Im2, are already known to the processing unit 4.

[0062] Note that when the processing unit 4 outputs the measurement AC current Im1 and the measurement AC current Im2 from the measurement current output units 2-1 and 2-2, it is not necessary for the measurement AC current Im1 and the measurement AC current Im2 flowing through the power supply device PD to completely cancel each other out. However, the amplitudes of the measurement AC current Im1 and the measurement AC current Im2 do not have to be completely equal. However, the processing unit 4 controls the measurement current output units 2-1 and 2-2 so that the frequency of the measurement AC current Im1 and the frequency of the measurement AC current Im2 are equal and the phase of the measurement AC current Im1 and the phase of the measurement AC current Im2 are opposite. In other words, the processing unit 4 controls the measurement current output units 2-1 and 2-2 so that the frequency and phase of the measurement AC current Im1 and the frequency and phase of the measurement AC current Im2 are synchronized. In this case, an AC current Iac having a complex current value IL flows through the power supply device PD, and when a current sensor is built into the power supply device PD, for example, information on the complex current value IL of this AC current Iac can be output from the power supply device PD to the processing unit 4, or a current sensor that detects the complex current value IL of the AC current Iac flowing through the power supply device PD can be provided and the current sensor can output information on the complex current value IL to the processing unit 4. Therefore, the complex current value IL of the AC current Iac is known to the processing unit 4.

[0063] Alternatively, the measurer can set the complex current values ​​of the measurement AC currents Im1 and Im2 for the measurement current supply units 2-1 and 2-2 so that the frequencies, amplitudes, and phases of the measurement AC currents Im1 and Im2 are synchronized so that the measurement AC currents Im1 and Im2 cancel each other out and reduce the amplitude of the AC current Iac flowing through the power supply device PD. In this case, a configuration is adopted in which the measurement current supply units 2-1 and 2-2 output current value setting information to the processing unit 4 to specify the complex current values ​​of the measurement AC currents Im1 and Im2 to be output. Even in this configuration, the complex current values ​​of the measurement AC currents Im1 and Im2 output from the measurement current supply units 2-1 and 2-2 are already known to the processing unit 4.

[0064] In this case, as shown in FIG. 2, the measurement AC current Im1 of the complex current value I1 output from the measurement current supply unit 2-1 is branched into a measurement AC current Im1 of complex current value I1a flowing through a flow path consisting of one output unit of the measurement current supply unit 2-1, the measurement current supply line Li, the probe Pi1, the terminal T1 of the DUT under test, the electrochemical cells C1 to C5, the terminal T6 of the DUT under test, the probe Pi3, the measurement current supply line Li, and the other output unit of the measurement current supply unit 2-1, and a measurement AC current Im1 of complex current value I1b flowing through a flow path consisting of one output unit of the measurement current supply unit 2-1, the measurement current supply line Li, the probe Pi1, the bus bar Bb, the power supply device PD, the bus bar Bb, the terminal T11 of the DUT under test, the electrochemical cells C10 to C6, the terminal T6 of the DUT under test, the probe Pi3, the measurement current supply line Li, and the other output unit of the measurement current supply unit 2-1.

[0065] Furthermore, the measurement AC current Im2 of the complex current value I2 output from the measurement current supply unit 2-2 is branched into a measurement AC current Im2 of the complex current value I2a that flows through a flow path consisting of one output unit of the measurement current supply unit 2-2, the measurement current supply line Li, the probe Pi2, terminal T11 of the DUT under test, electrochemical cells C10 to C6, terminal T6 of the DUT under test, the probe Pi3, the measurement current supply line Li, and the other output unit of the measurement current supply unit 2-2, and a measurement AC current Im2 of the complex current value I2b that flows through a flow path consisting of one output unit of the measurement current supply unit 2-2, the measurement current supply line Li, the probe Pi2, the bus bar Bb, the power supply device PD, the bus bar Bb, terminal T1 of the DUT under test, electrochemical cells C1 to C5, terminal T6 of the DUT under test, the probe Pi3, the measurement current supply line Li, and the other output unit of the measurement current supply unit 2-2. In this case, 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 bus bar Bb. In other words, the bus bar Bb serves as an active line through which the DC current flows.

[0066] As shown in the figure, the AC current consisting of the measurement AC currents Im1 and Im2 flowing through the electrochemical cells C1 to C5 is also referred to as the AC current Iac with a complex current value IZ1, and the AC current consisting of the measurement AC currents Im1 and Im2 flowing through the electrochemical cells C10 to C6 is also referred to as the AC current Iac with a complex current value IZ2. In order to simply show the flow paths of the measurement AC currents Im1 and Im2, the figure only shows the components associated with the flow paths and their reference numerals.

[0067] In this case, the measurement current supply unit 2-2 supplies a measurement AC current Im2, whose frequency, amplitude, and phase are synchronized with the measurement AC current Im1, to the electrochemical cell C in the DUT under test in accordance with the frequency control signal Sf2 output from the processing unit 4 so that the measurement AC current Im2 and the measurement AC current Im1 cancel each other out, thereby reducing the amplitude of the AC current Iac flowing through the power supply device PD. Therefore, in a measurement AC current supply state in which the measurement AC current Im1 is supplied across the electrochemical cells C1 to C5 in the DUT under test and the measurement AC current Im2 is supplied across the electrochemical cells C6 to C10 in the DUT under test, the measurement AC current Im1 and the measurement AC current Im2 cancel each other out in the flow path including the power supply device PD. In other words, in this measurement AC current supply state, the complex current value IL of the AC current Iac composed of the measurement AC currents Im1 and Im2 is reduced.

[0068] In this case, the frequency and phase of the measurement AC current Im1 flowing through the power supply device PD are synchronized with the frequency and phase of the measurement AC current Im2. Therefore, if there is a slight difference between the amplitude of the measurement AC current Im1 flowing through the power supply device PD and the amplitude of the measurement AC current Im2 flowing through the power supply device PD, for example, when the direction of the AC current Iac flowing through the power supply device PD is from the measurement current output unit 2-1 to terminal T11 (the other end) of the DUT under test, the measurement AC current Im1 with the above-mentioned complex current value I1b is shunted to the power supply device PD. Conversely, when the direction of the AC current Iac flowing through the power supply device PD is from the measurement current output unit 2-2 to terminal T1 (one end) of the DUT under test, the measurement AC current Im2 with the above-mentioned complex current value I2b is shunted to the power supply device PD.

[0069] Here, the direction of the AC current Iac from the measurement current output unit 2-1 toward the terminal T11 (the other end) of the DUT under test means that the phase of the AC current Iac flowing through the power supply device PD is positive relative to the phase of the measurement AC current Im1 output from the measurement current output unit 2-1. In other words, this means that the phase of the AC current Iac (measurement AC current Im1) flowing through the power supply device PD is within a range of 90° to −90° (first and fourth quadrants) relative to the reference phase. Hereinafter, this state of the AC current Iac will also be referred to as “when the phase of the AC current Iac is positive.” On the other hand, the direction of the AC current Iac from the measurement current output unit 2-2 toward the terminal T1 (one end) of the DUT under test means that the phase of the AC current Iac flowing through the power supply device PD is positive relative to the phase of the measurement AC current Im2 output from the measurement current output unit 2-2. In other words, this means that the phase of the AC current Iac (measurement AC current Im2) flowing through the power supply device PD is within a range of 90° to -90° (first and fourth quadrants) with respect to the reference phase. In other words, because the frequency and phase of the measurement AC current Im1 and the frequency and phase of the measurement AC current Im2 are synchronized, this means that the phase of the AC current Iac (measurement AC current Im1) flowing through the power supply device PD is within a range of 90° to 270° (second and third quadrants) with respect to the reference phase, using the phase of the measurement AC current Im1 output from the measurement current output unit 2-1 as the reference phase. Hereinafter, this state of the AC current Iac will also be referred to as "when the phase of the AC current Iac is negative."

[0070] As a result, when the phase of the AC current Iac is positive, the complex current value IZ1 of the AC current Iac flowing through the electrochemical cells C1 to C5 is the complex current value I1 of the measurement AC current Im1 output from the measurement current output unit 2-1 minus the complex current value IL of the AC current Iac. Hereinafter, this complex current value IZ1 will also be referred to as the complex current value (I1-IL) of the AC current Iac. Furthermore, the complex current value IZ2 of the AC current Iac flowing through the electrochemical cells C6 to C10 is the complex current value I2 of the measurement AC current Im2 output from the measurement current output unit 2-2 plus the complex current value IL of the AC current Iac. Hereinafter, this complex current value IZ2 will also be referred to as the complex current value (I2+IL) of the AC current Iac.

[0071] On the other hand, when the phase of the AC current Iac is negative, the complex current value IZ1 of the AC current Iac flowing through the electrochemical cells C1 to C5 is the complex current value obtained by adding the complex current value I1 of the measurement AC current Im1 output from the measurement current output unit 2-1 to the complex current value IL of the AC current Iac. Hereinafter, this complex current value IZ1 will also be referred to as the complex current value (I1 + IL) of the AC current Iac. Furthermore, the complex current value IZ2 of the AC current Iac flowing through the electrochemical cells C6 to C10 is the complex current value obtained by subtracting the complex current value IL of the AC current Iac from the complex current value I2 of the measurement AC current Im2 output from the measurement current output unit 2-2. Hereinafter, this complex current value IZ2 will also be referred to as the complex current value (I2 - IL) of the AC current Iac.

[0072] Therefore, since the processing unit 4 knows the complex current value I1 of the measurement AC current Im1 output from the measurement current output unit 2-1, the complex current value IL of the AC current Iac flowing through the power supply device PD, and the complex voltage value V1 detected by the voltage detection unit 3-1 (described later), it can calculate the impedance of the measurement target electrochemical cell C in the first group G1 based on the complex current value I1, the complex current value IL, and the complex voltage value V1. Furthermore, since the processing unit 4 knows the complex current value I2 of the measurement AC current Im2 output from the measurement current output unit 2-2, the complex current value IL of the AC current Iac flowing through the power supply device PD, and the complex voltage value V2 detected by the voltage detection unit 3-2 (described later), it can calculate the impedance of the measurement target electrochemical cell C in the second group G2 based on the complex current value I2, the complex current value IL, and the complex voltage value V2. Furthermore, because the measurement AC currents Im1 and Im2 cancel each other out within the flow path through the power supply device PD, the AC current Iac flows through the electrochemical cells C1 to C5 at a sufficiently large complex current value IZ1 and also flows through the electrochemical cells C6 to C10 at a sufficiently large complex current value IZ2.

[0073] In this measurement AC current supply state, the voltage detection unit 3-1, under the control of the processing unit 4, detects a complex voltage value V1 across both ends of electrochemical cells C2 and C3 under measurement among some of the electrochemical cells C1 to C5 in the DUT under measurement, and outputs voltage value data Dv1 indicating the complex voltage value V1 to the processing unit 4. Furthermore, the voltage detection unit 3-2, under the control of the processing unit 4, detects a complex voltage value V2 across both ends of electrochemical cells C7 to C10 under measurement among other electrochemical cells C6 to C10 in the DUT under measurement, and outputs voltage value data Dv2 indicating the complex voltage value V2 to the processing unit 4.

[0074] In this case, as described above, because almost none of the measurement AC currents Im1 and Im2 are shunted to the power supply device PD, the complex current value IZ1 of the measurement AC current Im1 shunted to the electrochemical cells C1 to C5 and the complex current value IZ2 of the measurement AC current Im2 shunted to the electrochemical cells C6 to C10 become large, resulting in large complex voltages V1 and V2 generated across the measurement target electrochemical cells C2 to C3 and C7 to C10. This increases the ratio (S / N) of the signal level (S) of the complex voltages V1 and V2 measured by each voltage detection unit 3 to the noise level (N), allowing the impedance to be calculated (measured) with high accuracy in the impedance calculation process performed by the processing unit 4, which will be described later.

[0075] Next, processing unit 4 receives voltage value data Dv output from each voltage detection unit 3 and determines complex voltage value V1 for electrochemical cells C2 and C3 under measurement, as well as complex voltage value V2 for electrochemical cells C7 to C10 under measurement. Processing unit 4 also measures (calculates) the impedance of each of electrochemical cells C2 to C3 and C7 to C10 under measurement based on known complex current value IZ1 of AC current Iac flowing through electrochemical cells C2 and C3 under measurement, known complex current value IZ2 of AC current Iac flowing through electrochemical cells C7 to C10 under measurement, and the determined complex voltage values ​​V1 and V2.

[0076] Specifically, the processing unit 4 calculates the phase difference (θ) between the AC current Iac (measurement AC current Im1) flowing through the electrochemical cells C2 and C3 and the AC voltages generated across the electrochemical cells C2 and C3 based on the complex current value IZ1 (current value I) and the complex voltage value V1 (voltage value V). The processing unit 4 also calculates the phase difference (θ) between the AC current Iac (measurement AC current Im2) flowing through the electrochemical cells C7 to C10 and the AC voltages generated across the electrochemical cells C7 to C10 based on the complex current value IZ2 (I) and the complex voltage value V2 (V). Next, based on the current value (I), voltage value (V), and phase difference (θ) calculated in this manner, processing unit 4 measures (calculates) the impedance (impedance Z=V / I, R=Z·cosθ, X=Z·sinθ) of each of electrochemical cells C2 to C3, C7 to C10, which are the cells to be measured.

[0077] In this case, when the phase of the AC current Iac flowing through the power supply device PD is positive, the processing unit 4 calculates the impedances of the electrochemical cells C2 to C3 under measurement using the complex current value (I1-IL) as the complex current value IZ1 as the current value I, and calculates the impedances of the electrochemical cells C7 to C10 under measurement using the complex current value (I2+IL) as the complex current value IZ2 as the current value I. Furthermore, when the phase of the AC current Iac flowing through the power supply device PD is negative, the processing unit 4 calculates the impedances of the electrochemical cells C2 to C3 under measurement using the complex current value (I1+IL) as the complex current value IZ1 as the current value I, and calculates the impedances of the electrochemical cells C7 to C10 under measurement using the complex current value (I2-IL) as the complex current value IZ2 as the current value I.

[0078] The processing unit 4 also outputs a frequency control signal Sf1 to the measurement current supply unit 2-1 and a frequency control signal Sf2 to the measurement current supply unit 2-2, thereby synchronously sweeping the frequencies of the measurement AC currents Im1 and Im2. The processing unit 4 then measures (calculates) the impedances of the electrochemical cells C2-C3, C7-C10 at multiple frequencies as described above. The processing unit 4 then acquires the frequency characteristics of the impedances of the electrochemical cells C2-C3, C7-C10 at multiple frequencies. In this case, the processing unit 4 acquires, as frequency characteristics, Cole-Cole plots that show the impedance characteristics of the electrochemical cell C versus frequency, and Bode plots that show the gain and phase characteristics versus frequency. The processing unit 4 then outputs display data Dd to the output unit 5, causing the display device of the output unit 5 to display the measured impedances of the electrochemical cells C2-C3, C7-C10 and the acquired Cole-Cole plots and Bode plots. Furthermore, the processing unit 5 outputs the measurement data Dm to the recording unit 6, and records the measured impedances of the electrochemical cells C2 to C3, C7 to C10 as well as the acquired Cole-Cole plots and Bode diagrams. This completes the process of measuring the impedances of the electrochemical cells C2 to C3, C7 to C10 by the processing unit 5. Similarly, when measuring the impedances of the other electrochemical cells C, the processing unit 5 performs the same impedance measurement process as described above.

[0079] Furthermore, when measuring the impedance of the entire DUT under test, probe Pi1 is connected to terminal T1 of the DUT under test, probe Pi2 is connected to terminal T11 of the DUT under test, and probe Pi2 is connected to terminal T6 of the DUT under test. Furthermore, probe Pv1 is connected to terminal T1 of the DUT under test, probe Pv2 is connected to terminal T6 of the DUT under test, probe Pv3 is connected to terminal T6 of the DUT under test, and probe Pv4 is connected to terminal T11 of the DUT under test. Then, a measurement instruction is output from the operation unit to the processing unit 4. In this case, in accordance with the measurement instruction, the processing unit 4 calculates the impedance of all electrochemical cells C1 to C5 in the first group G1 as the measurement target electrochemical cells C, and calculates the impedance of all electrochemical cells C6 to C10 in the second group G2 as the measurement target electrochemical cells C, and then calculates the sum of the calculated impedances of all electrochemical cells C1 to C5 in the first group G1 and the calculated impedances of all electrochemical cells C6 to C10 in the second group G2 as the impedance of the measurement target DUT. In this way, the impedance of the entire measurement target DUT is measured by a single impedance measurement.

[0080] Furthermore, processing unit 4 acquires the frequency characteristics of the impedance of the DUT under test at multiple frequencies in the same manner as acquiring the frequency characteristics of the impedance for electrochemical cell C under test. Thereafter, processing unit 4 outputs display data Dd to output unit 5, causing the measured impedance of the DUT under test and the acquired Cole-Cole plot and Bode plot to be displayed on the display device of output unit 5. Processing unit 5 also outputs measurement data Dm to recording unit 6, recording the measured impedance of the DUT under test and the acquired Cole-Cole plot and Bode plot. This completes the impedance measurement process for the DUT under test by processing unit 5.

[0081] In addition, when only the electrochemical cells C belonging to either the first group G1 or the second group G2 are the electrochemical cells C to be measured, and the electrochemical cells C belonging to the other group are not the electrochemical cells C to be measured, only one of the voltage detection units 3-1, 3-2 corresponding to one of the groups can be arranged as the first voltage detection unit, and the other of the voltage detection units 3-1, 3-2 can be omitted.

[0082] As described above, in the impedance measurement device 1 and the impedance measurement method, a measurement AC current Im1 is supplied across both ends of some of the electrochemical cells C1 to C5 that are located between terminals T1 and T6 among the plurality of electrochemical cells C, and a measurement AC current Im2 that is synchronized with the measurement AC current Im1 in frequency, amplitude, and phase is supplied across some of the remaining electrochemical cells C6 to C10 that are located between terminals T6 and T11 among the plurality of electrochemical cells C so that the measurement AC current Im2 and the measurement AC current Im2 cancel each other out, thereby reducing the amplitude of the AC current Iac flowing through the power supply device PD. In the measurement AC current supply state, a complex voltage value V1 is detected across both ends of the electrochemical cell C to be measured that is one of the electrochemical cells C1 to C5, and the impedance of the electrochemical cell C to be measured is measured based on the complex current value I1 of the measurement AC current Im1, the complex current value IL of the AC current Iac flowing through the power supply device PD, and the detected complex voltage value V1.

[0083] Furthermore, in this impedance measuring device 1 and impedance measuring method, when a measurement AC current is being supplied, a complex voltage value V2 across both ends of the measurement target electrochemical cell C among the other electrochemical cells C6 to C10 is detected, and the impedance of the measurement target electrochemical cell C in the second group G2 is measured based on the complex current value I2 of the measurement AC current Im2, the complex current value IL of the AC current Iac flowing through the power supply device PD, and the detected complex voltage value V2.

[0084] Furthermore, in this impedance measuring device 1 and impedance measuring method, when the direction of the AC current Iac flowing through the power supply device PD is toward the terminal T11 of the DUT under test, the impedance of the electrochemical cell C under test in the first group G1 is calculated based on the complex current value IZ1 (I1-IL) obtained by subtracting the complex current value IL of the AC current Iac flowing through the power supply device PD from the complex current value I1 of the AC current Im1 to obtain a complex current value (I1-IL) and the detected complex voltage value V1; and the impedance of the electrochemical cell C under test in the second group G2 is calculated based on the complex current value (I2+IL) obtained by adding the complex current value I2 of the AC current Im2 to the complex current value IL of the AC current Iac flowing through the power supply device PD and the detected complex voltage value V2.

[0085] Furthermore, in this impedance measuring device 1 and impedance measuring method, when the direction of the AC current Iac is toward the terminal T1 of the DUT under test, the impedance of the electrochemical cell C under test in the first group G1 is calculated based on the complex current value (I1+IL) as the complex current value IZ1 obtained by adding the complex current value I1 of the measurement AC current Im1 and the complex current value IL of the AC current Iac flowing through the power supply device PD, and the detected complex end-to-end voltage value V1; and the impedance of the electrochemical cell C under test in the second group G2 is calculated based on the complex current value (I2-IL) as the complex current value IZ2 obtained by subtracting the complex current value IL of the AC current Iac flowing through the power supply device PD from the complex current value I2 of the measurement AC current Im2, and the detected complex end-to-end voltage value V2.

[0086] Therefore, according to this impedance measuring device 1 and impedance measuring method, even when the impedance of the power supply device PD connected in parallel to the DUT under test via the bus bar Bb is extremely small, it is possible to supply the measurement AC currents Im1 and Im2 to the electrochemical cell C under test, thereby making it possible to measure the complex current values ​​IZ1 and IZ2 of the AC current Iac flowing through the electrochemical cell C under test and the complex voltage values ​​V1 and V2 across the electrochemical cell C under test when the measurement AC currents Im1 and Im2 are supplied to the electrochemical cell C under test.As a result, it is possible to reliably measure the impedance of the electrochemical cell C under test and the DUT under test.

[0087] Furthermore, with this impedance measuring device 1 and impedance measuring method, only a small amount of the measurement AC currents Im1 and Im2 is shunted to the power supply device PD, which causes the complex current value IZ1 of the measurement AC current Im1 flowing through the electrochemical cells C1 to C5 and the complex current value IZ2 of the measurement AC current Im2 flowing through the electrochemical cells CC6 to C10 to be large. As a result, the complex voltage values ​​V1 and V2 generated across each of the electrochemical cells C1 to C10 are large. As a result, with this impedance measuring device 1 and impedance measuring method, the ratio (S / N) of the signal level (S) of the detected complex voltage values ​​V1 and V2 across the electrochemical cells C to the noise level (N) can be sufficiently increased, making it possible to measure the impedance of the measurement target electrochemical cell C and the measurement target DUT with sufficiently high accuracy.

[0088] Furthermore, the impedance measuring device 1 and the impedance measuring method measure the impedance of the electrochemical cell C in the DUT under test, which is configured by electrically connecting electrochemical cells C that cause electrochemical reactions in series. Therefore, the impedance measuring device 1 and the impedance measuring method can accurately measure the impedance of the electrochemical cell C under test and the DUT under test while the DUT under test and the power supply device PD are operating.

[0089] Furthermore, with this impedance measuring device 1 and impedance measuring method, the frequency characteristics of the impedance of the electrochemical cell C to be measured or the DUT to be measured at multiple frequencies can be obtained, thereby making it possible to determine the performance and deterioration state of the electrochemical cell C to be measured or the DUT to be measured.

[0090] Furthermore, according to this impedance measuring device 1 and impedance measuring method, by acquiring either a Cole-Cole plot or a Bode plot as the frequency characteristics, it is possible to determine with high accuracy the performance and degradation state of the electrochemical cell C to be measured or the DUT to be measured.

[0091] Furthermore, according to the impedance measuring device 1 and the impedance measuring method, the acquired frequency characteristics can be recorded in the recording section, thereby realizing the function of a recording device.

[0092] (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.

[0093] Unlike the impedance measuring device 1, the impedance measuring device 1A includes a current sensor 7-1 that constitutes a first current detection unit. Furthermore, a processing unit 4A of the impedance measuring device 1A executes the same processing as that of the processing unit 4, but differs from the processing unit 4 in that it executes processing to input current value data Di1 indicating a complex current value IL of the AC current Iac flowing through the power supply device PD from the current sensor 7-1. For this reason, the processing of the processing unit 4A that differs from that of the processing unit 4 will be described below.

[0094] 3, the current sensor 7-1 is disposed between the connection point of the probe Pi1 on the bus bar Bb and the power supply device PD. The current sensor 7-1 detects a complex current value IL of an AC current Iac made up of measurement AC currents Im1 and Im2 flowing through the power supply device PD, and outputs current value data Di1 indicating the complex current value IL to the processing unit 4B.

[0095] In this case, the current sensor 7-1 may be, for example, a current sensor such as that disclosed in Japanese Patent Application Laid-Open No. 2014-235045, and is configured as a clamp-type ammeter capable of contactlessly clamping a conductor such as a coated metal conductor. Specifically, the current sensor 7-1 is configured with two semicircular magnetic cores 7a and 7b and a magnetic detection element 7c 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 operation unit (not shown) to bring the magnetic cores 7a and 7b close to each other to form an annular opening 7d. In current sensor 7-1, magnetic detection element 7c detects magnetic flux generated in magnetic cores 7a and 7b when a current flows through the conductor inserted in opening 7d, 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 indicating the measured current value. However, current sensor 7-1 may also be a type of sensor 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 unable to be opened or closed may also be used.

[0096] During impedance measurement, the processing unit 4A inputs the current value data Di1 output from the current sensor 7-1, and determines whether the direction of the AC current Iac flowing through the power supply device PD is toward the terminal T11 of the DUT to be measured or toward the terminal T1 of the DUT to be measured, based on the phase of the AC current Iac contained in the current value data Di1 and the phase of the measurement AC current Im1 output from the measurement current output unit 2-1.

[0097] Specifically, as described above, the processing unit 4 determines, based on the phase of the measurement AC current Im1 output from the measurement current output unit 2-1, that when the phase of the AC current Iac flowing through the power supply device PD is positive, the direction of the AC current Iac flowing through the power supply device PD is toward terminal T11 of the DUT under measurement, and when the phase of the AC current Iac flowing through the power supply device PD is negative, the direction of the AC current Iac flowing through the power supply device PD is toward terminal T1 of the DUT under measurement.

[0098] During impedance measurement, when the processing unit 4A determines that the direction of the AC current Iac flowing through the power supply device PD is toward terminal T11 of the DUT under test, it calculates the complex current value IZ1 of the AC current Iac flowing through the electrochemical cells C1 to C5 as a complex current value (I1-IL) and calculates the complex current value IZ2 of the AC current Iac flowing through the electrochemical cells C6 to C10 as a complex current value (I2+IL). On the other hand, when the processing unit 4A determines that the direction of the AC current Iac flowing through the power supply device PD is toward terminal T1 of the DUT under test, it calculates the complex current value IZ1 of the AC current Iac flowing through the electrochemical cells C1 to C5 as a complex current value (I1+IL) and calculates the complex current value IZ2 of the AC current Iac flowing through the electrochemical cells C6 to C10 as a complex current value (I2-IL).

[0099] Next, processing unit 4A calculates the phase difference (θ) between the AC current Iac (measurement AC current Im1) flowing through electrochemical cells C2 and C3 and the AC voltages generated across both ends of the electrochemical cells C2 and C3 based on the complex current value IZ1 (current value I) and the complex voltage value V1 (voltage value V), in the same manner as processing unit 4. Processing unit 4A also calculates the phase difference (θ) between the AC current Iac (measurement AC current Im2) flowing through electrochemical cells C7 to C10 and the AC voltages generated across both ends of the electrochemical cells C7 to C10 based on the complex current value IZ2 (I) and the complex voltage value V2 (V). Next, based on the current value (I), voltage value (V), and phase difference (θ) calculated in this manner, processing unit 4A measures (calculates) the impedance (impedance Z=V / I, R=Z·cosθ, X=Z·sinθ) of each of electrochemical cells C2 to C3, C7 to C10, which are the cells to be measured.

[0100] In addition, when only the electrochemical cells C belonging to either the first group G1 or the second group G2 are the electrochemical cells C to be measured, and the electrochemical cells C belonging to the other group are not the electrochemical cells C to be measured, only one of the voltage detection units 3-1, 3-2 corresponding to one of the groups can be arranged as the first voltage detection unit, and the other of the voltage detection units 3-1, 3-2 can be omitted.

[0101] In this way, the impedance measuring device 1A and the impedance measuring method detect the complex current value IL of the AC current Iac, and when the direction of the detected AC current Iac is toward the terminal T11 of the DUT under measurement, the impedance of the electrochemical cell C under measurement in the first group G1 is measured based on the complex current value (I1-IL) obtained by subtracting the complex current value IL of the detected AC current Iac from the complex current value I1 of the measurement AC current Im1, and the detected complex end-to-end voltage value V1.

[0102] Furthermore, in this impedance measuring device 1A and impedance measuring method, the complex current value IL of the AC current Iac is detected, and when the direction of the detected AC current Iac is toward the terminal T11 of the DUT under measurement, the impedance of the electrochemical cell C under measurement in the second group G1 is measured based on the complex current value (I2+IL) obtained by adding the complex current value I2 of the measurement AC current Im2 and the complex current value IL of the detected AC current Iac, and the detected complex end-to-end voltage value V2.

[0103] Furthermore, in this impedance measuring device 1A and impedance measuring method, the complex current value IL of the AC current Iac is detected, and when the direction of the detected AC current Iac is toward the terminal T1 of the DUT under measurement, the impedance of the electrochemical cell C under measurement in the first group G1 is measured based on the complex current value (I1+IL) obtained by adding the complex current value I1 of the measurement AC current Im1 and the complex current value IL of the detected AC current Iac, and the detected complex end-to-end voltage value V1.

[0104] Furthermore, in this impedance measuring device 1A and impedance measuring method, the complex current value IL of the AC current Iac is detected, and when the direction of the detected AC current Iac is toward the terminal T1 of the DUT under measurement, the impedance of the electrochemical cell C under measurement in the second group G2 is measured based on the complex current value (I2-IL) obtained by subtracting the complex current value IL of the detected AC current Iac from the complex current value I2 of the measurement AC current Im2, and the detected complex voltage value V2 across both ends.

[0105] Therefore, according to this impedance measuring device 1A and impedance measuring method, it is possible to actually detect the complex current value IL of the AC current Iac flowing through the power supply device PD, and therefore it is possible to more accurately measure (calculate) the complex current values ​​IZ1, IZ2 of the AC current Iac flowing through the electrochemical cell C under measurement, and as a result, it is possible to more accurately measure (calculate) the impedance of the electrochemical cell C under measurement.

[0106] (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 apparatuses 1 and 1A will be omitted.

[0107] Impedance measuring device 1B is configured by adding current sensor 7-2, which constitutes a second current detection unit, and current sensor 7-3, which constitutes a third current detection unit, to the configuration of impedance measuring device 1A. Furthermore, processing unit 4B of impedance measuring device 1B performs the same processing as processing unit 4A, but differs from processing unit 4A in that it receives, from current sensor 7-2, current value data Di2 indicating the complex current value I1 of measurement AC current Im1 output from measurement current output unit 2-1, and current value data Di3 indicating the complex current value I2 of measurement AC current Im2 output from measurement current output unit 2-2, from current sensor 7-3. Therefore, the following description of processing unit 4B will focus on the processing that differs from processing unit 4A.

[0108] 4, the current sensor 7-2 is the same as the current sensor 7-1 described above and is disposed on the measurement current supply line Li connected to one output of the measurement current supply unit 2-1. The current sensor 7-2 detects a complex current value I1 of the measurement AC current Im1 output from the measurement current supply unit 2-1 and flowing through the measurement current supply line Li, and outputs current value data Di2 indicating the complex current value I1 to the processing unit 4B. The current sensor 7-3 is the same as the current sensor 7-1 described above and is disposed on the measurement current supply line Li connected to one output of the measurement current supply unit 2-2. The current sensor 7-3 detects a complex current value I2 of the measurement AC current Im2 output from the measurement current supply unit 2-2 and flowing through the measurement current supply line Li, and outputs current value data Di3 indicating the complex current value I2 to the processing unit 4B.

[0109] Similar to processing unit 4A, processing unit 4B receives current value data Di1 output from current sensor 7-1 during impedance measurement to determine complex current value IL of AC current Iac flowing through power supply device PD. Processing unit 4B also receives current value data Di2 output from current sensor 7-2 to determine complex current value I1 of measurement AC current Im1 output from measurement current output unit 2-1, and receives current value data Di3 output from current sensor 7-3 to determine complex current value I2 of measurement AC current Im2 output from measurement current output unit 2-2.

[0110] During impedance measurement, current sensor 7-2 detects complex current value I1 of measurement AC current Im1 and outputs current value data Di2 indicating complex current value I1 to processing unit 4B, and current sensor 7-3 detects complex current value I2 of measurement AC current Im2 and outputs current value data Di3 indicating complex current value I2 to processing unit 4B. Therefore, processing unit 4B can actually measure and determine accurate complex current values ​​I1 and I2 of measurement AC currents Im1 and Im2 without obtaining current value setting information for measurement current output units 2-1 and 2-2. Therefore, the processing unit 4B can accurately calculate the complex current value (I1-IL) or the complex current value (I1+IL), which is the complex current value IZ1 of the AC current Iac flowing through the electrochemical cells C1 to C5, and can also accurately calculate the complex current value (I2+IL) or the complex current value (I2-IL), which is the complex current value IZ2 of the AC current Iac flowing through the electrochemical cells C6 to C10.

[0111] Next, in the same manner as processing unit 4A, processing unit 4B measures (calculates) the impedance of the electrochemical cell C to be measured based on the complex current value IZ1 of the AC current Iac flowing through the electrochemical cell C to be measured, the complex current value IZ2 of the AC current Iac flowing through the electrochemical cell C to be measured, and the complex end-to-end voltage values ​​V1 and V2.

[0112] When only the electrochemical cells C belonging to the first group G1 (or the second group G2) are to be measured, the current sensor 7-3 (or the current sensor 7-2) may be omitted. This configuration allows the impedance of the electrochemical cells C to be measured that belong to the first group G1 (or the second group G2) to be accurately measured (calculated) based on the complex current value I1 (or the complex current value I2) of the actually detected measurement AC current Im1 (or the measurement AC current Im2) and the detected complex voltage value V1 (or the complex voltage value V2).

[0113] Furthermore, in this impedance measuring device 1B, when only the electrochemical cells C belonging to either the first group G1 or the second group G2 are the electrochemical cells C to be measured, and the electrochemical cells C belonging to the other group are not the electrochemical cells C to be measured, only one of the voltage detection units 3-1, 3-2 corresponding to one of the groups can be arranged as the first voltage detection unit, and the other of the voltage detection units 3-1, 3-2 can be omitted.

[0114] In this way, the impedance measuring device 1B and the impedance measuring method can actually measure and grasp the complex current values ​​I1 and I2 of the measurement AC currents Im1 and Im2 accurately without acquiring current value setting information for the measurement current output units 2-1 and 2-2. Therefore, the impedance measuring device 1B and the impedance measuring method can accurately measure (calculate) the impedance of the electrochemical cell C to be measured.

[0115] (Fourth Example) Next, an impedance measuring apparatus 1C will be described with reference to Fig. 5. Note that components and operations similar to those of the impedance measuring apparatuses 1, 1A, and 1B are given the same reference numerals and redundant description will be omitted.

[0116] This impedance measuring apparatus 1C is an example of an impedance apparatus that performs an impedance measurement method, and differs from the impedance measuring apparatuses 1, 1A, and 1B in that it includes measurement current supply units 2A-1 and 2A-2, which are configured as electronic loads that function as current sources, instead of the measurement current supply units 2-1 and 2-2. Note that this embodiment will be described with reference to a diagram in which the measurement current supply unit 2 in the impedance measuring apparatus 1B has been replaced with measurement current supply units 2A-1 and 2A-2, but the same operation and the same effects can be achieved even if the measurement current supply unit 2 in the impedance measuring apparatus 1 and 1A is replaced with measurement current supply units 2A-1 and 2A-2.

[0117] In this impedance measuring device 1C, at the start of impedance measurement, the processing unit 4B outputs a frequency control signal Sf1 to the measurement current supply unit 2A-1 to operate the measurement current supply unit 2A-1 as an AC load. In response to the frequency control signal Sf1, the measurement current supply unit 2A-1 consumes the DC current output from the power supply unit PD as a load, thereby supplying a measurement AC current Im1 of the specified frequency, amplitude, and phase to the electrochemical cell C under test and the power supply unit PD via the measurement current supply line Li and probes Pi1 and Pi3. The processing unit 4B also outputs a frequency control signal Sf2 to the measurement current supply unit 2A-2 to operate the measurement current supply unit 2A-2 as an AC load. In response to the frequency control signal Sf2, the measurement current supply unit 2A-2 consumes the DC current output from the power supply unit PD as a load, thereby supplying a measurement AC current Im2 of the specified frequency, amplitude, and phase to the electrochemical cell C under test and the power supply unit PD via the measurement current supply line Li and probes Pi2 and Pi3. In this state, the processing unit 4B executes the impedance measurement process described above to measure the impedance of the electrochemical cell C under measurement based on the complex current values ​​IZ1 and IZ2 flowing through the electrochemical cell C under measurement and the complex voltage values ​​V1 and V2 across the electrochemical cell C under measurement.

[0118] According to this impedance measuring device 1C and impedance measuring method, the measurement AC currents Im1 and Im2 are supplied from an electronic load, and the electronic load consumes the DC current output from the power supply device PD to generate the measurement AC currents Im1 and Im2, thereby generating large measurement AC currents Im1 and Im2. Therefore, according to this impedance measuring device 1C and impedance measuring method, the complex current values ​​IZ1 and IZ2 (I) and the complex end-to-end voltage values ​​V1 and V2 (V) can be increased, making it possible to accurately measure (calculate) the complex current values ​​IZ1 and IZ2 of the AC current Iac flowing through the electrochemical cell C under test, as well as to accurately measure (calculate) the complex end-to-end voltage values ​​V1 and V2. As a result, it is possible to accurately measure (calculate) the impedance of the electrochemical cell C under test and the DUT under test.

[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, an example in which two voltage detection units 3-1 and 3-2 are provided has been described, but a configuration in which only one of the voltage detection units 3 is provided, or a configuration in which the two voltage detection units 3-1 and 3-2 are integrated, can also be adopted.

[0120] Although the current sensors 7-1 to 7-3 output current value data Di1 to Di3 in the above example, it is also possible to employ a configuration in which the current sensors 7-1 to 7-3 output analog current measurement signals, and the processing units 4, 4A, and 4B measure (calculate) impedance based on the input current measurement signals. Similarly, it is also possible to employ a configuration in which the voltage detection units 3-1 and 3-2 output analog voltage measurement signals, and the processing units 4, 4A, and 4B measure (calculate) impedance based on the input voltage measurement signals.

[0121] In the above embodiment, the current sensors 7-1 to 7-3 are configured as openable / closable clamp-type non-contact current sensors, but current sensors with other configurations can also be used. For example, a current sensor configured to be non-openable using a shunt resistor or annular core can be placed at the connection between the measurement current supply unit 2 and the measurement current supply line Li, or the measurement current supply line Li can be inserted into the opening of a current sensor configured to be non-openable, thereby enabling accurate measurement of the complex current values ​​I1 and I2 of the measurement AC currents Im1 and Im2. Furthermore, when a large DC current is output from the power supply device PD, the current sensor 7-1 can also be configured as an air-core Rogowski coil capable of measuring AC current.

[0122] In the above embodiment, the probe Pi3 is connected to the terminal T at a position where the number of electrochemical cells C in the first group G1 and the number of electrochemical cells C in the second group G2 are equal or nearly equal to each other, but this is not limiting. As long as a measurement AC current Im1 is supplied between both ends of the electrochemical cells C in the first group G1 and a measurement AC current Im2 whose frequency, amplitude, and phase are synchronized with the measurement AC current Im2 is supplied between both ends of the electrochemical cells C in the second group G2 so that the measurement AC current Im1 and the measurement AC current Im2 cancel each other out, thereby reducing the amplitude of the AC current Iac flowing through the power supply device PD, the probe Pi2 can be connected to any terminal T of the DUT under test as an intermediate point. [Industrial Applicability]

[0123] According to the present invention, even when a low-impedance non-measurement object is connected in parallel to a measurement object configured by connecting multiple impedance elements in series, it is possible to measure the complex current value of the AC current flowing through the first measurement object impedance element and the complex voltage value across both ends of the first measurement object impedance element when the first measurement AC current and the second measurement AC current are supplied to the first measurement object impedance element and the second measurement object impedance element, thereby reliably measuring the impedance of the first 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]

[0124] 1, 1A~1C Impedance measuring device 2-1,2-2,2A-1,2A-2 Measurement current supply section 3-1, 3-2 Voltage detection section 4, 4A, 4B Processing section 5 Output section 6 Recording section 7-1~7-3 Current Sensor Bb busbar C1~C10 Electrochemical Cells Di1~Di3 current value data DUT Measurement target Dv1, Dv2 voltage value data PD power supply T1~T11 terminals

Claims

1. An impedance measuring device that measures the impedance of an impedance element in a state in which a measurement target configured by connecting a plurality of impedance elements in series between one end and the other end and a non-measurement target are connected in parallel via a connection line, a first measurement current supply unit that supplies a first measurement AC current between both ends of some of the impedance elements that are located between the one end and the intermediate portion of the plurality of impedance elements; a second measurement current supply unit that supplies a second measurement AC current, the frequency, amplitude, and phase of which are synchronized with the first measurement AC current, between both ends of another part of the impedance elements that are located between the other end and the intermediate portion of the plurality of impedance elements, so that the second measurement AC current and the first measurement AC current cancel each other out and the amplitude of the AC current flowing through the non-measurement object becomes smaller; a first voltage detection unit that detects a complex voltage value across both ends of a first impedance element to be measured among the partial impedance elements in a measurement AC current supply state in which the first measurement AC current is supplied between both ends of the partial impedance elements and the second measurement AC current is supplied between both ends of the other partial impedance elements; and a processing unit that calculates the impedance of the first measurement target impedance element based on the complex current value of the first measurement target AC current output from the first measurement current supply unit in the measurement target AC current supply state, the complex current value of the AC current flowing through the non-measurement target, and the complex end-to-end voltage value detected by the first voltage detection unit.

2. a first current detection unit that detects a complex current value of an AC current flowing through the object to be measured; 2. The impedance measuring device according to claim 1, wherein, when the direction of the AC current detected by the first current detection unit is toward the other end of the object to be measured, the processing unit calculates the impedance of the first object to be measured based on a complex current value obtained by subtracting the complex current value of the AC current detected by the first current detection unit from the complex current value of the first measurement AC current output from the first measurement current supply unit, and on the complex end-to-end voltage value detected by the first voltage detection unit.

3. a first current detection unit that detects a complex current value of an AC current flowing through the object to be measured; 2. The impedance measuring device according to claim 1, wherein, when the direction of the AC current detected by the first current detection unit is toward the one end of the measurement object, the processing unit calculates the impedance of the first measurement object impedance element based on a complex current value obtained by adding together the complex current value of the first measurement AC current output from the first measurement current supply unit and the complex current value of the AC current detected by the first current detection unit, and based on the complex end-to-end voltage value detected by the first voltage detection unit.

4. 3. The impedance measuring device according to claim 2, further comprising a second current detecting section that detects a complex current value of the first measurement AC current output from the first measurement current supplying section.

5. 4. The impedance measuring device according to claim 3, further comprising a second current detecting section that detects a complex current value of the first measurement AC current output from the first measurement current supplying section.

6. a third current detection unit that detects a complex current value of the second measurement AC current output from the second measurement current supply unit; a second voltage detection unit configured to detect a complex voltage value across both ends of a second impedance element to be measured among the other part of impedance elements in the measurement AC current supply state, 5. The impedance measuring device according to claim 4, wherein the processing unit calculates the impedance of the second measurement target impedance element based on a complex current value obtained by adding together the complex current value of the second measurement AC current output from the second measurement current supply unit, which is detected by the third current detection unit, and the complex current value of the AC current detected by the first current detection unit, and based on the complex end-to-end voltage value detected by the second voltage detection unit.

7. a third current detection unit that detects a complex current value of the second measurement AC current output from the second measurement current supply unit; a second voltage detection unit configured to detect a complex voltage value across both ends of a second impedance element to be measured among the other part of impedance elements in the measurement AC current supply state, 6. The impedance measuring device according to claim 5, wherein the processing unit calculates the impedance of the second measurement target impedance element based on a complex current value obtained by subtracting the complex current value of the AC current detected by the first current detection unit from the complex current value of the second measurement AC current output from the second measurement current supply unit, detected by the third current detection unit, and the complex end-to-end voltage value detected by the second voltage detection unit.

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

9. 8. The impedance measuring device according to claim 1, wherein the impedance measuring device measures the impedance of an impedance element within the measurement object, the impedance element being configured by electrically connecting impedance elements that cause an electrochemical reaction in series.

10. the first measurement current supply unit is configured to be able to vary the frequency of the first measurement AC current in accordance with a frequency control signal; the second measurement current supply unit is configured to be able to vary the frequency of the second measurement AC current in accordance with a frequency control signal; 2. The impedance measuring device according to claim 1, wherein the processing unit acquires the frequency characteristics of the impedance of the impedance element by outputting the frequency control signal to the first measurement current supply unit and the second measurement current supply unit to vary the frequencies of the first measurement AC current and the second measurement AC current.

11. The impedance measuring device according to claim 10 , wherein the processing unit acquires one of a Cole-Cole plot and a Bode diagram as the frequency characteristics.

12. 12. The impedance measuring device according to claim 10, wherein the processing unit records the acquired frequency characteristics in a recording unit.

13. An impedance measurement method for measuring the impedance of an impedance element in a state in which a measurement target configured by connecting a plurality of impedance elements in series between one end and the other end and a non-measurement target are connected in parallel via a connection line, the method comprising: supplying a first measurement AC current between both ends of some of the impedance elements located between the one end and the intermediate portion of the plurality of impedance elements; supplying a second measurement AC current, the frequency, amplitude and phase of which are synchronized with those of the first measurement AC current, between both ends of another part of the impedance elements located between the other end and the intermediate part among the plurality of impedance elements, so that the second measurement AC current and the first measurement AC current cancel each other out and the amplitude of the AC current flowing through the non-measurement object becomes smaller; detecting a complex voltage value across both ends of a first impedance element to be measured among the partial impedance elements in a measurement AC current supply state in which the first measurement AC current is supplied between the two ends of the partial impedance elements and the second measurement AC current is supplied between the two ends of the other partial impedance elements; an impedance measurement method for measuring the impedance of the first measurement target impedance element based on a complex current value of the first measurement AC current output from the first measurement current supply unit in the measurement AC current supply state, a complex current value of the AC current flowing through the non-measurement target, and the complex end-to-end voltage value detected by the first voltage detection unit.

14. Detecting a complex current value of an AC current flowing through the object to be measured; 14. The impedance measurement method according to claim 13, wherein, when the direction of the detected AC current is toward the other end of the object to be measured, the impedance of the first object to be measured is measured based on a complex current value obtained by subtracting the complex current value of the detected AC current from the complex current value of the first AC current for measurement, and the detected complex voltage value across both ends.

15. Detecting a complex current value of an AC current flowing through the object to be measured; 14. The impedance measurement method according to claim 13, wherein, when the direction of the detected AC current is toward the one end of the measurement target, the impedance of the first measurement target impedance element is measured based on a complex current value obtained by adding the complex current value of the first measurement AC current and the complex current value of the detected AC current, and the detected complex end-to-end voltage value.

16. 15. The impedance measuring method according to claim 14, wherein a complex current value of the first measurement AC current is detected.

17. 16. The impedance measuring method according to claim 15, wherein a complex current value of the first measurement AC current is detected.

18. Detecting a complex current value of the second measurement AC current; In the measurement AC current supply state, a complex voltage value across both ends of a second impedance element to be measured among the other part of impedance elements is detected; 17. The impedance measurement method according to claim 16, wherein the impedance of the second impedance element to be measured is measured based on a complex current value obtained by adding the complex current value of the detected second measurement AC current and the complex current value of the detected AC current, and the complex end-to-end voltage value at both ends of the detected second impedance element to be measured.

19. Detecting a complex current value of the second measurement AC current; In the measurement AC current supply state, a complex voltage value across both ends of a second impedance element to be measured among the other part of impedance elements is detected; 18. The impedance measurement method according to claim 17, wherein the impedance of the second impedance element to be measured is measured based on a complex current value obtained by subtracting the complex current value of the detected AC current from the complex current value of the detected second measurement AC current, and the complex end-to-end voltage value at both ends of the second impedance element to be measured.

20. 20. The impedance measuring method according to claim 13, wherein the first measuring AC current and the second measuring AC current are supplied from an electronic load.

21. 20. The impedance measuring method according to claim 13, wherein the impedance of an impedance element within the measurement object is measured, the impedance element being configured by electrically connecting in series impedance elements that cause an electrochemical reaction.

22. The impedance measuring method according to claim 13, wherein the frequency of the first measuring AC current and the second measuring AC current is varied to obtain the frequency characteristics of the impedance of the impedance element.

23. The impedance measuring method according to claim 22, wherein one of a Cole-Cole plot and a Bode plot is obtained as the frequency characteristics.

24. 24. The impedance measuring method according to claim 22 or 23, wherein the acquired frequency characteristics are recorded in a recording unit.

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