Impedance measuring apparatus and impedance measuring method

Abstract

The present invention measures the impedance of impedance elements in a state in which a measurement target, which is formed by connecting a plurality of impedance elements in series, and a non-measurement target are connected in parallel.　The present invention comprises: a measurement current supply unit 2-1 which supplies a measurement AC current Im1 between both ends of electrochemical cells C2, C3; a measurement current supply unit 2-2 which supplies a measurement AC current Im2 between both ends of electrochemical cells C7-C10; a voltage detection unit 3-1 which detects a complex terminal voltage value V1 across the electrochemical cells C2, C3; and a processing unit 4 which calculates the impedance of the electrochemical cells C2, C3 on the basis of the complex terminal voltage value V1 detected by the voltage detection unit 3-1 and a complex current value IZ1 of an AC current Iac detected by a current sensor 7-1 in a state in which the measurement AC current Im2 and the measurement AC current Im1 flowing through a power supply device PD cancel each other.

Description

Impedance measuring device and impedance measuring method

[0001] The present invention relates to an impedance measuring device and an impedance measuring method that can measure the impedance of some or all of a plurality of impedance elements 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.

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

[0003] When measuring the internal impedance of a secondary battery using this impedance measuring device, first, a power line is inserted through the opening of the clamp-type current sensor in the AC current detection unit. In this state, the AC current supply unit supplies a measurement AC current between the power lines. As a result, a portion of the measurement AC current flows through the secondary battery. Furthermore, 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. The flow of the feedback current generates an AC voltage across the detection resistor. Next, the A / D conversion unit A / D converts the detected AC current 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.

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

[0005] However, the above-described impedance measuring device has the following problems. As conceptually shown in FIG. 6 , the problem of using the above-described impedance measuring device 1X to measure the impedance of an operating DUT, such as an electrolysis device (electrolysis device) that generates hydrogen and oxygen, will be specifically described. In this case, the DUT is connected in parallel to a power supply device PD that supplies DC current to the DUT via a power supply line Lp. Therefore, when measuring the impedance of an operating DUT, the AC current supply unit U1 supplies a measurement AC current Im to the DUT via the measurement current supply line Li and terminals T1 and T11 at both ends of the DUT. In this state, the current sensor U4 measures the current value of the measurement AC current Im flowing through the DUT, and the AC voltage detection unit U2 detects the AC voltage value generated between the terminals T1 and T11 of the DUT. Next, the calculation control unit U3 measures the impedance of the DUT under test based on the current value of the measurement AC current Im detected by the current sensor U4 and the voltage value of the AC voltage measured by the AC voltage detection unit U2.

[0006] In this case, the impedance of the power supply device PD in the operating state is extremely small compared to the impedance of the DUT under test. Therefore, in the measurement state shown in FIG. 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 both ends of the DUT under test. Therefore, this impedance measurement device 1X has the problem of being unable to measure the impedance of the DUT under test when a low-impedance object to be measured is connected in parallel to the DUT under test.

[0007] The present invention has been made in consideration of such problems, and its main object is to provide an impedance measuring device and an impedance measuring method that can measure the impedance of 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.

[0008] In order to achieve the above object, an 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, the impedance measuring device including 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 first measurement AC current that is adjusted in frequency, amplitude and phase 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 first measurement AC current cancel each other out and the amplitude of the AC current flowing through the non-measurement object becomes small. a first A current detection unit that detects a complex current value of the AC current flowing through the certain impedance elements; a first voltage detection unit that detects a complex voltage value across both ends of a first impedance element to be measured 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 impedance element to be measured based on the complex current value of the AC current detected by the first A current detection unit and the complex voltage value across both ends detected by the first voltage detection unit in the measurement AC current supply state.

[0009] 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, the first 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 is small. a second measurement AC current whose frequency, amplitude, and phase are synchronized with those of the first measurement AC current so as to obtain a complex current value; a complex current value of the AC current flowing through the certain impedance elements is detected; in a measurement AC current supply state in which the first measurement AC current is supplied between the two ends of the certain impedance elements and the second measurement AC current is supplied between the two ends of the other certain impedance elements, a complex voltage value across both ends of a first impedance element to be measured among the certain impedance elements is detected; and the impedance of the first impedance element to be measured is measured based on the detected complex current value of the AC current and the detected complex voltage value across both ends in the measurement AC current supply state.

[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 a connection line is extremely small, the first measurement AC current and the second measurement AC current can be supplied to the first measurement object impedance element and the second measurement object impedance element, so that 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 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 enabling the impedance of the first measurement object impedance element to be reliably measured.

[0011] The impedance measuring device according to the present invention also includes 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 certain 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 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 second measurement AC current output from the second measurement current supply unit in the measurement AC current supply state, and on the complex voltage value detected by the second voltage detection unit.

[0012] Furthermore, the impedance measurement method according to the present invention detects a complex voltage value across both ends of a second impedance element to be measured among the other impedance elements in the measurement AC current supply state, 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 a complex current value obtained by adding the complex current value of the first measurement AC current and the complex current value of the second measurement AC current, and the detected complex voltage value across both ends of the second impedance element to be measured.

[0013] 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 a connection line is extremely small, the first measurement AC current and the second measurement AC current can be supplied to the first measurement object impedance element and the second measurement object impedance element, so that it is possible to measure the complex current value of the AC current flowing through the second measurement object impedance element and the complex end-to-end voltage value of the second 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 making it possible to reliably measure the impedance of the second measurement object impedance element and the measurement object.

[0014] The impedance measuring device according to the present invention also includes a second current detection unit that detects the 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 second measurement AC current output from the second measurement current supply unit.

[0015] Furthermore, the impedance measuring method according to the present invention detects the complex current value obtained by adding the complex current value of the first measurement AC current and the complex current value of the second measurement AC current.

[0016] This impedance measuring device and impedance measuring method can actually detect a complex current value obtained by adding the complex current value of the first AC current to the complex current value of the second AC current. This makes it possible to more accurately measure (calculate) the complex current value of the AC current flowing through the first impedance element to be measured and the second impedance element to be measured, and as a result, it is possible to more accurately measure (calculate) the impedance of the first impedance element to be measured and the second impedance element to be measured.

[0017] In addition, the impedance measuring device according to the present invention includes a first B current detection unit that detects a complex current value of an AC current flowing through the other part of impedance elements, and a second voltage detection unit that detects 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, and the processing unit calculates the impedance of the second impedance element to be measured based on the complex current value detected by the first B current detection unit and the complex voltage value detected by the second voltage detection unit in the measurement AC current supply state.

[0018] Furthermore, the impedance measurement method according to the present invention detects a complex current value of the AC current flowing through the other part of impedance elements, detects 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, and measures the impedance of the second impedance element to be measured based on the complex current value of the AC current flowing through the other part of impedance elements detected in the measurement AC current supply state and the detected complex voltage value across both ends of the second impedance element to be measured.

[0019] According to this impedance measuring device and impedance measuring method, the complex current value of the AC current flowing through some of the other impedance elements can actually be detected, so that the complex current value of the AC current can be measured more accurately, and as a result, the impedance of the second impedance element to be measured can be measured (calculated) more accurately.

[0020] 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.

[0021] 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.

[0022] 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 end-to-end voltage value of 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 and to accurately measure (calculate) the complex end-to-end voltage value, and as a result, it is possible to accurately measure (calculate) the impedance of the first and second impedance elements to be measured and the impedance of the measurement targets.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] In addition, in the impedance measuring device according to 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 outputs 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, thereby acquiring the frequency characteristics of the impedance of the impedance element.

[0027] Furthermore, in the impedance measuring method according to the present invention, the frequency of the first measurement AC current and the second measurement AC current is varied to obtain the frequency characteristic of the impedance of the impedance element.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] In the impedance measuring device according to the present invention, the processing unit records the acquired frequency characteristics in a recording unit.

[0033] In addition, in the impedance measuring method according to the present invention, the acquired frequency characteristics are recorded in a recording unit.

[0034] According to this impedance measuring device and impedance measuring method, it is possible to realize the function of a recording device.

[0035] 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 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 making it possible to reliably measure the impedance of the first measurement object impedance element.

[0036] FIG. 1 is a configuration diagram showing the configuration of an impedance measuring device 1. FIG. 2 is an explanatory diagram for explaining the flow paths of measurement AC currents Im1 and Im2 in a measurement AC current supply state. FIG. 3 is a configuration diagram showing the configuration of an impedance measuring device 1A. FIG. 4 is a configuration diagram showing the configuration of an impedance measuring device 1B. FIG. 5 is a configuration diagram showing the configuration of an impedance measuring device 1C. FIG. 6 is an explanatory diagram for explaining how to use a conventional impedance measuring device 1X.

[0037] 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.

[0038] The impedance measuring device 1 shown in Figure 1 is an example of an impedance device that performs an impedance measurement method, and is configured to be able to measure the impedance of a measurement target impedance element, with some or all of the impedance elements being the measurement target impedance elements, in a state where a measurement target DUT configured by connecting multiple impedance elements in series is connected in parallel to a power supply device PD as a non-measurement target via a bus bar Bb as a connection line that functions as a power supply line.

[0039] In this case, examples of the DUT to be measured 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 include power supply devices such as inverter devices and converter devices, various loads such as electronic devices, and various power generation devices such as operating or non-operating fuel cells. An example of an electrolytic reduction device is an organic electrolytic reduction device used in the production of MCH (methylcyclohexane), a hydrogen carrier (see JP 2022-30943 A).

[0040] 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 will describe 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 test.

[0041] 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, also referred to as "electrochemical cells C" when not distinguishing between them) in a stacked configuration. While an electrolysis device is actually configured by connecting tens to hundreds of electrochemical cells C in series, in this example, for ease of understanding, the DUT under test is configured by electrically connecting 10 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, also referred to as "terminals T" when not distinguishing between terminals T1 to T11) connected to the connection points of each electrochemical cell 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, the terminal T (terminal T6 in the figure) with which the probe Pi3 comes into contact corresponds to the middle part of the object to be measured.

[0042] First Example Next, the configuration of the impedance measuring device 1 will be described. As shown in Fig. 1, the 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, a processing unit 4, an output unit 5, a recording unit 6, a current sensor 7-1, probes Pi1 to Pi3 for supplying measurement currents, and probes Pv1 to Pv4 for detecting voltages. Note that, hereinafter, when the measurement current supply units 2-1 and 2-2 are not distinguished, they are also referred to as "measurement current supply units 2," when the voltage detection units 3-1 and 3-2 are not distinguished, they are also referred to as "voltage detection unit 3," when the probes Pi1 to Pi3 are not distinguished, they are also referred to as "probes Pi," and when the probes Pv1 to Pv4 are not distinguished, they are also referred to as "probes Pv."

[0043] 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. Furthermore, a measurement current supply line Li is connected to one output terminal and the other output terminal of the measurement current supply unit 2-1. 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.

[0044] 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 the frequency control signal Sf1 output from the processing unit 4. In this case, because 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.

[0045] 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, a measurement current supply line Li is connected to one output terminal and the other output terminal of the measurement current supply unit 2-2. 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 and Li and the probes Pi2 and Pi3.

[0046] The measurement current supply unit 2-2 is also 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 also sweeps (varies) the frequency of the measurement AC current Im2 and outputs it in accordance with the frequency control signal Sf2. Furthermore, because the measurement current supply unit 2-2 is a current source, its output impedance is extremely large. Hereinafter, when the measurement AC currents Im1 and Im2 are not distinguished from each other, 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 the remaining 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.

[0047] 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 currents 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.

[0048] The voltage detection unit 3 detects the voltage input 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."

[0049] Furthermore, the voltage detection unit 3-1 detects a complex voltage value V1 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 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."

[0050] The processing unit 4 is configured, for example, by 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 and inputs current value data Di1-1 (described later) output from the current sensor 7-1. During impedance measurement, the processing unit 4 measures (calculates) the impedance 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 impedance of some or all of the electrochemical cells C6 to C10 in the second group G2 as measurement target electrochemical cells C, as described later.

[0051] 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, thereby synchronizing the frequency, amplitude, and phase of the measurement AC currents Im1 and Im2 and sweeping them between the low frequency band and the high frequency band. The processing unit 4 also outputs display data Dd to the output unit 5 for displaying the measured impedance of the electrochemical cell C under test, the impedance of the DUT under test as a whole, and the frequency characteristics of the impedance, such as the Cole-Cole plot and Bode plot (described below). The processing unit 5 also outputs measurement data Dm, which indicates 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 the Cole-Cole plot and Bode plot, to the recording unit 6 for recording.

[0052] The output unit 5 is, for example, a display device such as a liquid crystal panel or an organic EL panel, and receives the display data Dd output from the processing unit 4 to display the impedance of the electrochemical cell C under test, the impedance of the entire DUT under test, 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 entire DUT under test, 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.

[0053] The current sensor 7-1 constitutes a first A current detection unit and is disposed between the connection point of the probe Pi1 on the bus bar Bb and the terminal T1 of the DUT under test. The current sensor 7-1 detects a complex current value IZ1 of an AC current Iac made up of the measurement AC current Im1 and the measurement AC current Im2 flowing through some of the electrochemical cells C belonging to the first group G1 in the DUT under test, and outputs current value data Di1-1 indicating the complex current value IZ1 to the processing unit 4.

[0054] 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 that can clamp a conductor such as a coated metal conductor in a non-contact manner. 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 non-contact current sensor that can 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 through 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 Di1-1 indicating the measured current value. However, current sensor 7-1 may be a type that can measure the current value of high-frequency signals other than DC, and instead of a clamp-type current sensor, a current sensor that uses an annular core and cannot be opened or closed may be used.

[0055] The probes Pi1 to Pi3 are contact-type probes whose tips are connected (contacted) directly or indirectly to the terminals T of the DUT to be measured, respectively, for supplying measurement AC currents Im1 and Im2. The probes Pv1 to Pv4 are contact-type probes whose tips are connected (contacted) directly or indirectly to the terminals T of the DUT to be measured, respectively, for measuring the complex end-to-end voltage V generated across the terminals T, T when the measurement AC currents Im1 and Im2 are supplied to the electrochemical cell C to be measured.

[0056] 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 designated 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.

[0057] 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 test, it is preferable to select the terminals T as the intermediate portion of the DUT under test 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. Furthermore, by selecting the intermediate terminals 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 cells C under test.

[0058] Furthermore, probes Pv1 to Pv4 are connected to terminal T of the DUT under test. In this case, as an example, some of the electrochemical cells C belonging to the first group G1, namely, electrochemical cells C2 and C3, are designated as electrochemical cells under test C, and some of the electrochemical cells C belonging to the second group G2, namely, electrochemical cells C7 to C10, are designated as electrochemical cells under test C. 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.

[0059] 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 a measurement AC current Im2 whose frequency, amplitude, and phase are synchronized with 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 are reduced, i.e., so that the complex current value IL of the AC current Iac flowing through the power supply device PD is reduced. 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.

[0060] 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 measurement AC current Im1 and the measurement AC current Im2 cancel each other out, reducing 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 for specifying 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.

[0061] 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 a complex current value I1a that flows 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 a complex current value I1b that flows 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.

[0062] 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 a 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, 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 2-2, and a measurement AC current Im2 of a 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, 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 2-2. In this case, the DC current output from the power supply device PD flows through the electrochemical cells C1 to C10 in the DUT via the bus bar Bb. In other words, the bus bar Bb is an active line through which the DC current flows.

[0063] 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.

[0064] 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 between both ends of the electrochemical cells C1 to C5 in the DUT under test and the measurement AC current Im2 is supplied between both ends of 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, which is composed of the measurement AC currents Im1 and Im2, is reduced.

[0065] In this measurement AC current supply state, current sensor 7-1 detects a complex current value IZ1 of AC current Iac, which is made up of measurement AC current Im1 and measurement AC current Im2, flowing through electrochemical cells C1 to C5 belonging to first group G1 in the measurement target DUT, and outputs current value data Di1-1 indicating this complex current value IZ1 to processing unit 4. Also, in this measurement AC current supply state, voltage detection unit 3-1, under the control of processing unit 4, detects a complex end-to-end voltage value V1 across measurement target electrochemical cells C2 and C3, which are among some of the electrochemical cells C1 to C5 in the measurement target DUT, and outputs voltage value data Dv1 indicating the complex end-to-end voltage value V1 to processing unit 4. In addition, the voltage detection unit 3-2, under the control of the processing unit 4, detects a complex end-to-end voltage value V2 at both ends of the electrochemical cells C7 to C10 to be measured, which are one of the other electrochemical cells C6 to C10 in the DUT to be measured, and outputs voltage value data Dv2 indicating the complex end-to-end voltage value V2 to the processing unit 4.

[0066] In this case, as described above, since 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 the voltage detection units 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.

[0067] Next, the processing unit 4 determines the complex current value IZ1 of the AC current Iac flowing through the electrochemical cells C1-C5 based on the input current value data Di1-1. The processing unit 4 also determines the complex current value IZ2 of the AC current Iac flowing through the electrochemical cells C6-C10 belonging to the second group G2 in the DUT by subtracting the complex current value IZ1 of the AC current Iac detected by the current sensor 7-1 from the complex current value IA obtained by adding the known complex current value I1 of the measurement AC current Im1 output from the measurement current output unit 2-1 and the known complex current value I2 of the measurement AC current Im2 output from the measurement current supply unit 2-2 in the measurement AC current supply state. In this case, the complex current value IA is equal to the complex current value obtained by adding the complex current values ​​IZ1 and IZ2 of the AC current Iac. Therefore, by subtracting the complex current value IZ1 from the complex current value IA, the complex current value IZ2 of the AC current Iac can be accurately determined.

[0068] Next, the processing unit 4 receives the voltage value data Dv output from each voltage detection unit 3 and determines the complex voltage value V1 for the electrochemical cells C2 and C3 under measurement and the complex voltage value V2 for the electrochemical cells C7 to C10 under measurement. The processing unit 4 also measures (calculates) the impedances of the electrochemical cells C2 to C3 and C7 to C10 under measurement based on the complex current value IZ1 of the AC current Iac flowing through the electrochemical cells C2 and C3 under measurement, the complex current value IZ2 of the AC current Iac flowing through the electrochemical cells C7 to C10 under measurement, and the determined complex voltage values ​​V1 and V2.

[0069] 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·cos θ, X=Z·sin θ) of each of electrochemical cells C2 to C3, C7 to C10, which are the measurement target cells.

[0070] 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 showing the impedance characteristics of the electrochemical cell C with respect to frequency, and Bode plots showing the gain and phase characteristics with respect to 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, as well as the acquired Cole-Cole plots and Bode plots. The processing unit 5 also outputs the measurement data Dm to the recording unit 6, which records the measured impedances of the electrochemical cells C2-C3 and C7-C10 and the acquired Cole-Cole plots and Bode diagrams. This completes the process for measuring the impedances of the electrochemical cells C2-C3 and C7-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.

[0071] 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 processing unit 4. In this case, in accordance with the measurement instruction, the processing unit 4 calculates the impedances of all of the electrochemical cells C1 to C5 in the first group G1 as the measurement target electrochemical cells C, and also calculates the impedances of all of the 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 of the measurement target electrochemical cells C1 to C5 in the first group G1 and the calculated impedances of all of the measurement target 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.

[0072] Furthermore, the 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 the electrochemical cell C under test. Thereafter, the processing unit 4 outputs display data Dd to the output unit 5, causing the display device of the output unit 5 to display the measured impedance of the DUT under test and the acquired Cole-Cole plot and Bode plot. The processing unit 5 also outputs measurement data Dm to the 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 the processing unit 5.

[0073] In addition, when only the electrochemical cells C belonging to either the first group G1 or the second group G2 are set as the electrochemical cells C to be measured, and the electrochemical cells C belonging to the other group are not set as 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.

[0074] In this manner, in the impedance measuring device 1 and the impedance measuring method, a measurement AC current Im1 is supplied between both ends of some of the multiple electrochemical cells C, namely, electrochemical cells C1 to C5, which are located between terminals T1 and T6, and a measurement AC current Im2, whose frequency, amplitude, and phase are synchronized with those of the measurement AC current Im1, is supplied between both ends of some of the multiple electrochemical cells C, namely, electrochemical cells C6 to C10, which are located between terminals T6 and T11, 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, and the impedance of the electrochemical cell C to be measured is measured based on the complex current value IZ1 of the AC current Iac flowing through the electrochemical cells C1 to C5 detected in the measurement AC current supply state, and the detected complex voltage value V1 across both ends.

[0075] Furthermore, in this impedance measuring device 1 and impedance measuring method, in a state in which a measurement AC current is being supplied, a complex voltage value V2 across both ends of the measurement target electrochemical cell C7 to C10 among the other impedance elements C6 to C10 is detected, and the impedance of the measurement target electrochemical cell C is measured based on the complex current value IZ2 obtained by subtracting the complex current value IZ1 of the detected AC current Iac from the complex current value IA obtained by adding the complex current value I1 of the measurement AC current Im1 and the complex current value I2 of the measurement AC current Im2, and the detected complex voltage value V2.

[0076] 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 measurement 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 measurement, and it is therefore possible to measure the complex current values ​​IZ1 and IZ2 of the AC current Iac flowing through the electrochemical cell C under measurement, and the complex voltage values ​​V1 and V2 across the electrochemical cell C under measurement when the measurement AC currents Im1 and Im2 are supplied to the electrochemical cell C under measurement, thereby making it possible to reliably measure the impedance of the electrochemical cell C under measurement and the DUT under measurement.

[0077] Furthermore, in 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, this impedance measuring device 1 and impedance measuring method can sufficiently increase the ratio (S / N) of the signal level (S) of the detected complex voltage values ​​V1 and V2 to the noise level (N), thereby enabling the impedance of the measurement target electrochemical cell C and the measurement target DUT to be measured with sufficiently high accuracy.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] Second Embodiment Next, an 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.

[0083] Unlike the impedance measuring device 1, the impedance measuring device 1A includes a current sensor 7-2 that constitutes a second current detection unit. Furthermore, a processing unit 4A of the impedance measuring device 1A executes the same processing as the processing unit 4, but differs from the processing unit 4 in that it executes processing to input current value data Di2 from the current sensor 7-2 during impedance measurement. For this reason, the following description will focus on the processing of the processing unit 4A that differs from that of the processing unit 4.

[0084] 3, 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 the terminal T6 serving as the intermediate portion of the DUT. In addition, the current sensor 7-2 detects a complex current value IA obtained by adding the complex current value I1 of the measurement AC current Im1 output from the measurement current output unit 2-1 and the complex current value I2 of the measurement AC current Im2 output from the measurement current supply unit 2-2 in the measurement AC current supply state, and outputs current value data Di2 indicating the complex current value IA to the processing unit 4A. In this case, as described above, the measurement AC current Im1 is divided into a measurement AC current Im1 with a complex current value I1a and a measurement AC current Im1 with a complex current value I1b, but the measurement AC current Im1 output from one output section of the measurement current output section 2-1 and output from the probe Pi1 always returns to the other output section of the measurement current output section 2-1 via the probe Pi3. Also, as described above, the measurement AC current Im2 is divided into a measurement AC current Im2 with a complex current value I2a and a measurement AC current Im2 with a complex current value I2b, but the measurement AC current Im2 output from one output section of the measurement current output section 2-2 and output from the probe Pi2 always returns to the other output section of the measurement current output section 2-2 via the probe Pi3. Therefore, the complex current value IA detected by the current sensor 7-2 is always equal to the complex current value obtained by adding the measurement AC currents Im1 and Im2 flowing through the measurement current supply line Li, since the current sensor 7-2 is arranged on the measurement current supply line Li connected to the probe Pi3.

[0085] During impedance measurement, the processing unit 4A inputs the current value data Di2 output from the current sensor 7-2 and calculates a complex current value IA by adding the complex current value I1 of the measurement AC current Im1 and the complex current value I2 of the measurement AC current Im2. The processing unit 4A also calculates the complex current value IZ2 of the AC current Iac flowing through the electrochemical cells C6 to C10 belonging to the second group G2 in the DUT under measurement by subtracting the complex current value IZ1 of the AC current Iac detected by the current sensor 7-1 from the calculated complex current value IA.

[0086] During impedance measurement, the current sensor 7-2 detects a complex current value IA obtained by adding together the measurement AC currents Im1 and Im2, and outputs current value data Di2 indicating the complex current value IA to the processing unit 4 A. Next, the processing unit 4 A determines the complex current value IA obtained by adding together the measurement AC currents Im1 and Im2 based on the current value data Di2 output from the current sensor 7-2, and also determines the complex current value IZ2 of the AC current Iac flowing through the electrochemical cells C6 to C10 as described above.

[0087] Next, in the same manner as processing unit 4, processing unit 4A measures (calculates) the impedances of the electrochemical cells C2 to C3, C7 to C10 to be measured based on the complex current value IZ1 of the AC current Iac flowing through electrochemical cells C1 to C5, the complex current value IZ2 of the AC current Iac flowing through electrochemical cells C6 to C10, and the determined complex end-to-end voltage values ​​V1 and V2.

[0088] In addition, when only the electrochemical cells C belonging to either the first group G1 or the second group G2 are set as the electrochemical cells C to be measured, and the electrochemical cells C belonging to the other group are not set as 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.

[0089] In this way, the impedance measuring device 1A and the impedance measuring method detect a complex current value IA obtained by adding the complex current value I1 of the measurement AC current Im1 and the complex current value I2 of the measurement AC current Im2.

[0090] Therefore, according to this impedance measuring device 1A and impedance measuring method, it is possible to actually detect the complex current value IA obtained by adding the complex current value I1 of the measurement AC current Im1 and the complex current value I2 of the measurement AC current Im2, 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.

[0091] Third Embodiment Next, an impedance measuring apparatus 1B will be described with reference to Fig. 4. Note that duplicated descriptions of components and operations similar to those of the impedance measuring apparatus 1 will be omitted.

[0092] Unlike the impedance measuring device 1, the impedance measuring device 1B includes a current sensor 7-3 that constitutes a 1B current detection unit. Furthermore, a processing unit 4B of the impedance measuring device 1B executes the same processing as the processing unit 4, but differs from the processing unit 4 in the way in which the complex current value IZ2 of the AC current Iac is determined during impedance measurement. For this reason, the following description will focus on the processing of the processing unit 4B that differs from that of the processing unit 4.

[0093] 4, the current sensor 7-3 is the same as the current sensor 7-1 described above and is disposed between the connection point of the probe Pi2 on the bus bar Bb and the terminal T11 of the DUT under test. The current sensor 7-3 detects a complex current value IZ2 of an AC current Iac consisting of the measurement AC current Im1 and the measurement AC current Im2 flowing through another part of the electrochemical cells C belonging to the second group G2 in the DUT under test, and outputs current value data Di1-2 indicating the complex current value IZ2 to the processing unit 4B.

[0094] During impedance measurement, the processing unit 4B inputs the current value data Di2 output from the current sensor 7-3 and calculates the complex current value IZ2 of the AC current Iac.

[0095] During impedance measurement, the current sensor 7-3 detects a complex current value IZ2 of the AC current Iac, which is made up of the measurement AC current Im1 and the measurement AC current Im2, flowing through another portion of the electrochemical cells C belonging to the second group G2 in the DUT under measurement, and outputs current value data Di1-2 indicating the complex current value IZ2 to the processing unit 4B. Next, the processing unit 4B calculates the complex current value IZ2 of the AC current Iac based on the current value data Di1-2 output from the current sensor 7-3.

[0096] Next, in the same manner as processing unit 4, processing unit 4A 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.

[0097] 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.

[0098] In this way, the impedance measuring device 1B and the impedance measuring method detect the IZ2 of the AC current Iac flowing through the electrochemical cell C belonging to the second group G2, detect the complex end-to-end voltage value V2 across the two ends of the electrochemical cell C to be measured among the electrochemical cells C belonging to the second group G2 in the measurement AC current supply state, and measure the impedance of the electrochemical cell C to be measured based on the IZ2 of the AC current Iac detected in the measurement AC current supply state and the detected complex end-to-end voltage value V2.

[0099] Therefore, according to this impedance measuring device 1B and impedance measuring method, it is possible to actually detect the complex current value IZ2 of the AC current Iac flowing through the electrochemical cell C belonging to the second group G2, and as a result, it is possible to more accurately measure the complex current value IZ2 of the AC current Iac, and as a result, it is possible to more accurately measure (calculate) the impedance of the electrochemical cell C being measured.

[0100] Fourth Embodiment 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 denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0101] This impedance measuring device 1C is an example of an impedance device that performs an impedance measurement method, and differs from the impedance measuring devices 1, 1A, and 1B in that it includes measurement current supply units 2A-1 and 2A-2, which are configured with electronic loads that function as current sources, instead of the measurement current supply units 2-1 and 2-2. Note that in this embodiment, the description will be made with reference to a diagram in which the measurement current supply unit 2 in the impedance measuring device 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 devices 1 and 1A is replaced with measurement current supply units 2A-1 and 2A-2.

[0102] In this impedance measuring device 1C, at the start of impedance measurement, processing unit 4B outputs a frequency control signal Sf1 to measurement current supply unit 2A-1 to operate measurement current supply unit 2A-1 as an AC load. At this time, measurement current supply unit 2A-1 consumes the DC current output from power supply device PD as a load in accordance with the frequency control signal Sf1, thereby supplying a measurement AC current Im1 of the specified frequency, amplitude, and phase to the electrochemical cell C to be measured and power supply device PD via measurement current supply line Li and probes Pi1 and Pi3. Processing unit 4B also outputs a frequency control signal Sf2 to measurement current supply unit 2A-2 to operate measurement current supply unit 2A-2 as an AC load. At this time, the measurement current supply unit 2A-2 consumes the DC current output from the power supply device PD as a load in accordance with the frequency control signal Sf2, thereby supplying a measurement AC current Im2 of the specified frequency, amplitude, and phase to the electrochemical cell C under test and the power supply device 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 test based on the complex current values ​​IZ1 and IZ2 flowing through the electrochemical cell C under test and the complex end-to-end voltage values ​​V1 and V2.

[0103] According to the impedance measuring device 1C and the 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 the impedance measuring device 1C and the 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, thereby 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.

[0104] 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 is 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.

[0105] Although the example in which current sensors 7-1 to 7-3 output current value data Di1-1, Di1-2, and Di2 has been described, it is also possible to employ a configuration in which current sensors 7-1 to 7-3 output current measurement signals that are analog signals, and 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 voltage detection units 3-1 and 3-2 output voltage measurement signals that are analog signals, and processing units 4, 4A, and 4B measure (calculate) impedance based on the input voltage measurement signals.

[0106] In the above embodiment, current sensors 7-1 to 7-3 are configured as clamp-type non-contact current sensors that can be opened and closed. However, 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 value IA of the measurement AC currents Im1 and Im2. Furthermore, when a large DC current is output from the power supply device PD, current sensor 7-1 and current sensor 7-3 can also be configured as an air-core Rogowski coil capable of measuring AC current.

[0107] 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 approximately 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 as an intermediate point.

[0108] 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 making it possible to reliably measure 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.

[0109] 1, 1A to 1C Impedance measuring device 2-1, 2-2, 2A-1, 2A-2 Measurement current supply unit 3-1, 3-2 Voltage detection unit 4, 4A, 4B Processing unit 5 Output unit 6 Recording unit 7-1 to 7-3 Current sensor Bb Bus bar C1 to C10 Electrochemical cell Di1-1, Di1-2, Di2 Current value data DUT Measurement object Dv1, Dv2 Voltage value data PD Power supply unit T1 to T11 Terminal

Claims

1. An impedance measuring device for measuring the impedance of an impedance element in a state in which a measurement object configured by connecting multiple 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 device comprising: a first measurement current supply unit for supplying a first measurement AC current between both ends of some of the multiple impedance elements located between the one end and the intermediate portion; a second measurement current supply unit for supplying a second measurement AC current, the frequency, amplitude and phase of which are synchronized with the first measurement AC current, between both ends of other impedance elements located between the other end and the intermediate portion of the multiple impedance elements so that the first measurement AC current and the second measurement AC current cancel each other out and the amplitude of the AC current flowing through the non-measurement object becomes smaller; and a first A current detection unit for detecting the complex current value of the AC current flowing through the some of the impedance elements. an impedance measuring device comprising: a first voltage detection unit that detects a complex voltage value across both ends of a first impedance element to be measured among the certain impedance elements in a measurement AC current supply state in which the first measurement AC current is supplied across the ends of the certain impedance elements and the second measurement AC current is supplied across the ends of the other certain impedance elements; and a processing unit that calculates the impedance of the first impedance element to be measured based on the complex current value of the AC current detected by the first A current detection unit in the measurement AC current supply state and the complex voltage value across both ends detected by the first voltage detection unit.

2. The impedance measuring device according to claim 1, further comprising 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 part of 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 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 second measurement AC current output from the second measurement current supply unit in the measurement AC current supply state, and on the complex voltage value detected by the second voltage detection unit.

3. An impedance measuring device as described in claim 2, further comprising a second current detection unit that detects the 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 second measurement AC current output from the second measurement current supply unit.

4. An impedance measuring device as described in claim 1, comprising: a first B current detection unit that detects a complex current value of an AC current flowing through said other part of impedance elements; and a second voltage detection unit that detects a complex voltage value across both ends of a second impedance element to be measured among said other part of impedance elements in said measurement AC current supply state, wherein said processing unit calculates the impedance of said second impedance element to be measured based on the complex current value detected by said first B current detection unit and the complex voltage value detected by said second voltage detection unit in said measurement AC current supply state.

5. An impedance measuring device according to any one of claims 1 to 4, wherein the first measurement current supply unit and the second measurement current supply unit are constituted by electronic loads.

6. An impedance measuring device according to any one of claims 1 to 4, which 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.

7. The impedance measuring device according to claim 1, wherein 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 outputs 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, thereby acquiring the frequency characteristics of the impedance of the impedance element.

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

9. An impedance measuring device according to claim 7 or 8, wherein the processing unit records the acquired frequency characteristics in a recording unit.

10. 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 located between the one end and an intermediate portion; supplying a second measurement AC current, the frequency, amplitude and phase of which are synchronized with the first measurement AC current, between both ends of other impedance elements located between the other end and the intermediate portion of the plurality of impedance elements so that the first measurement AC current and the second 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 current value of the AC current flowing through the some of the impedance elements; and detecting a complex voltage value across both ends of a first measurement object impedance element among the some of the impedance elements in a measurement AC current supply state in which the first measurement AC current is supplied between the both ends of the some of the impedance elements and the second measurement AC current is supplied between the both ends of the other some of the impedance elements. An impedance measurement method for measuring the impedance of the first impedance element to be measured based on the detected complex current value of the AC current and the detected complex voltage value across both ends in the measurement AC current supply state.

11. The impedance measurement method according to claim 10, further comprising: detecting 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; and measuring 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 a complex current value obtained by adding the complex current value of the first measurement AC current and the complex current value of the second measurement AC current; and based on the detected complex voltage value across both ends of the second impedance element to be measured.

12. The impedance measuring method according to claim 11, wherein the complex current value is detected by adding the complex current value of the first measurement AC current and the complex current value of the second measurement AC current.

13. The impedance measurement method according to claim 10, further comprising the steps of: detecting a complex current value of an AC current flowing through the other part of impedance elements; detecting 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; and measuring the impedance of the second impedance element to be measured based on the detected complex current value of the AC current flowing through the other part of impedance elements in the measurement AC current supply state and the detected complex voltage value across both ends of the second impedance element to be measured.

14. The impedance measuring method according to any one of claims 10 to 13, wherein the first measuring AC current and the second measuring AC current are supplied from an electronic load.

15. An impedance measurement method according to any one of claims 10 to 13, which 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.

16. The impedance measuring method according to claim 10, 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.

17. The impedance measuring method according to claim 16, wherein either a Cole-Cole plot or a Bode plot is obtained as the frequency characteristics.

18. An impedance measuring method according to claim 16 or 17, wherein the acquired frequency characteristics are recorded in a recording unit.

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