Display device, impedance measurement device, and display method

Abstract

To provide a display device capable of accurately grasping an operating state or performance evaluation of a measurement subject by utilizing a current-voltage characteristic graph or the like.SOLUTION: A display device comprises a processing section 4 for causing a display screen to display at least one characteristic graph among: a current-voltage characteristic graph indicating the characteristic of a voltage value of a direct current voltage between terminals with respect to a current value of a direct current input / output through a measurement subject DUT1 via the terminals T1, T2; a current-power characteristic graph indicating the characteristic of a power value of power input / output via the terminals with respect to the current value of the direct current that is input / output; and a current-impedance characteristic graph indicating the characteristic of the impedance of the measurement subject DUT1 with respect to the current value of the direct current that is input / output. When one measurement point among a plurality of measurement points on one characteristic graph displayed on the display screen is selected, the processing section 4 displays, on the display screen, a cole-cole plot of the measurement subject DUT1 when a direct current of a current value corresponding to the selected measurement point is flowing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a display device and a display method suitable for grasping the operating state and performance evaluation of a measurement object by using at least one of a current-voltage characteristic graph (a characteristic graph showing the relationship between the voltage value of the input / output voltage and the current value of the input / output current: hereinafter, also referred to as an "I-V characteristic graph"), a current-power characteristic graph (a characteristic graph showing the relationship between the power value of the input / output power and the current value of the input / output current: hereinafter, also referred to as an "I-P characteristic graph"), and a current-impedance characteristic graph (a characteristic graph showing the relationship between the impedance of the measurement object and the current value of the input / output current: hereinafter, also referred to as an "I-Z characteristic graph") obtained from a measurement object such as a fuel cell or an electrolysis device (hereinafter, also referred to as an "electrolysis device"), and an impedance measurement device including the display device.

Background Art

[0002] For example, as a method for determining one performance of a fuel cell as a measurement object, a method for determining deterioration of a fuel cell stack disclosed in Patent Document 1 below is known. In this deterioration determination method, each current value of the direct current output from the fuel cell and the voltage value of the output voltage of the fuel cell when the direct current is output at each current value are measured, and an I-V characteristic graph showing the relationship between the voltage value with respect to the current value created based on the measurement values is used. Specifically, the I-V characteristic graph obtained at the initial stage of manufacturing the fuel cell is compared with the I-V characteristic graph obtained from the fuel cell that has changed over time due to use, and it is determined that the fuel cell has deteriorated when the decrease in the average output voltage of the fuel cell is large.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, by using the I-V characteristic graph, the degradation characteristics of the fuel cell can be evaluated. However, in order to fully evaluate the performance of the fuel cell, there are many other evaluation factors in addition to the above-described degradation characteristics. For example, when it is desired to maximize the output efficiency, which is a basic evaluation factor of the fuel cell, it is usually considered preferable to operate at an operating point where the output current is larger and the output voltage is higher. However, it is difficult to grasp whether the fuel cell is operating in an optimal operating state only by using the I-V characteristic graph. Specifically, for example, if the water content of the electrolyte membrane in the fuel cell is insufficient, if there is an excess or deficiency in the platinum catalyst used in the fuel cell, or if there is an excess or deficiency in the oxygen or hydrogen supplied to the fuel cell, it becomes difficult to operate the fuel cell in a state where the output efficiency is sufficient. However, it is extremely difficult to grasp in what actual state the fuel cell is operating at each measurement point of the I-V characteristic graph only by using the I-V characteristic graph. For this reason, it is desired to realize an apparatus and method that can fully grasp the operating state and performance evaluation of a measurement object such as a fuel cell by using the I-V characteristic graph.

[0005] In addition, there are also many evaluation factors in order to fully evaluate the performance of the electrolysis device. For example, when aiming to optimize the output efficiency, which is a basic evaluation factor of the electrolysis device, it is usually considered preferable to operate at an operating point where more hydrogen and oxygen can be output. However, it is difficult to determine whether the electrolysis device is operating in an optimal operating state by only using the I-V characteristic graph. Specifically, for example, if the water content of the electrolyte membrane in the electrolysis device is insufficient, there is an excess or deficiency in the platinum catalyst or iridium catalyst used in the electrolysis device, or there is an excess or deficiency in the amount of water supplied to the electrolysis device, it becomes difficult to operate the electrolysis device in a state where the output efficiency is sufficient. However, it is extremely difficult to grasp the actual operating state of the electrolysis device at each measurement point of the I-V characteristic graph by only using the I-V characteristic graph. For this reason, there is a desire to realize a device or method that can fully grasp the operating state and performance evaluation of a measurement target such as an electrolysis device by using an I-V characteristic graph. Similarly, there is a desire to realize a device or method that can fully grasp the operating state and performance evaluation of a fuel cell or an electrolysis device by using I-P characteristics or I-Z characteristics.

[0006] The present invention has been made in view of such problems, and a main object thereof is to provide a display device, an impedance measurement device, and a display method capable of accurately grasping the operating state and performance evaluation of a measurement target by using a current-voltage characteristic graph or the like.

Means for Solving the Problems

[0007] In order to achieve the above object, a display device according to the present invention includes a processing unit that displays on a display screen at least one characteristic graph among a current-voltage characteristic graph showing the characteristic of the voltage value of the DC voltage between a pair of terminals with respect to the current value of the DC current for inputting and outputting a measurement object via the pair of terminals, a current-power characteristic graph showing the characteristic of the power value of the power input and output via the pair of terminals with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, and a current-impedance characteristic graph showing the characteristic of the impedance of the measurement object with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals. When one of a plurality of measurement points on the one characteristic graph displayed on the display screen is selected, the processing unit displays on the display screen a call plot of the measurement object when the DC current having the current value corresponding to the selected measurement point is flowing.

[0008] Also, in order to achieve the above object, a display method according to the present invention is a display method for displaying on a display screen at least one characteristic graph among a current-voltage characteristic graph showing the characteristic of the voltage value of the DC voltage between a pair of terminals with respect to the current value of the DC current for inputting and outputting a measurement object via the pair of terminals, a current-power characteristic graph showing the characteristic of the power value of the power input and output via the pair of terminals with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, and a current-impedance characteristic graph showing the characteristic of the impedance of the measurement object with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals. When one of a plurality of measurement points on the one characteristic graph displayed on the display screen is selected, the call plot of the measurement object when the DC current having the current value corresponding to the selected measurement point is flowing is displayed on the display screen.

[0009] Also, in order to achieve the above object, a display device according to the present invention includes a processing unit that displays at least one characteristic graph among a current-voltage characteristic graph showing the characteristic of the voltage value of the DC voltage between a pair of terminals with respect to the current value of the DC current for inputting and outputting a measurement object via the pair of terminals, a current-power characteristic graph showing the characteristic of the power value of the power input and output via the pair of terminals with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, and a current-impedance characteristic graph showing the characteristic of the impedance of the measurement object with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals on a display screen. The processing unit displays a plurality of call plots of the measurement object when the DC current corresponding to the current value corresponding to each of a plurality of measurement points on the one characteristic graph is flowing on the display screen, and when one of the plurality of measurement points on the one characteristic graph displayed on the display screen is selected, the call plot corresponding to the selected measurement point is highlighted.

[0010] Also, in order to achieve the above object, a display method according to the present invention is a display method for displaying at least one characteristic graph among a current-voltage characteristic graph showing the characteristic of the voltage value of the DC voltage between a pair of terminals with respect to the current value of the DC current for inputting and outputting a measurement object via the pair of terminals, a current-power characteristic graph showing the characteristic of the power value of the power input and output via the pair of terminals with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, and a current-impedance characteristic graph showing the characteristic of the impedance of the measurement object with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals on a display screen. A plurality of call plots of the measurement object when the DC current corresponding to the current value corresponding to each of a plurality of measurement points on the one characteristic graph is flowing are displayed on the display screen, and when one of the plurality of measurement points on the one characteristic graph displayed on the display screen is selected, the call plot corresponding to the selected measurement point is highlighted.

[0011] According to these display devices and display methods, by allowing the measurement points on the characteristic graph to be selected, it is possible to display in cooperation each measurement point on the characteristic graph and the call plot corresponding to each measurement point. Therefore, according to these display devices and display methods, by displaying the characteristic graph and the call plot in cooperation, the user can accurately grasp the operating state and performance evaluation of the measurement target.

[0012] Further, the impedance measurement device according to the present invention includes the above-described display device, an AC voltage measurement unit, and an AC current measurement unit. The AC voltage measurement unit measures the voltage value of the AC voltage generated between both ends of the pair of terminals due to the measurement AC current flowing through the measurement target. The AC current measurement unit measures the current value of the measurement AC current flowing through the measurement target. The processing unit, at each of the measurement points where the current value of the DC current has changed, based on the frequency of the measurement AC current, the voltage value of the AC voltage measured by the AC voltage measurement unit, and the current value of the measurement AC current measured by the AC current measurement unit, acquires the frequency characteristics of the complex impedance of the measurement target for displaying the call plot on the display screen. Therefore, according to this impedance measurement device, in addition to the function of displaying the call plot, it is possible to generate display data for displaying the call plot based on the frequency characteristics of the complex impedance of the measurement target.

[0013] In addition, the impedance measurement device according to the present invention includes a direct current measurement unit and a direct current voltage measurement unit. The direct current measurement unit measures the current value of the direct current when the direct current with the superimposed measurement alternating current inputs and outputs the measurement target. The direct current voltage measurement unit measures the voltage value of the direct current voltage generated between both ends of the pair of terminals with respect to the changed current value of the direct current when the direct current with the superimposed measurement alternating current inputs and outputs the measurement target via the pair of terminals. The processing unit acquires display data for displaying at least one of the I-V characteristic graph and the I-P characteristic graph on the display screen based on the current value of the direct current measured by the direct current measurement unit and the voltage value of the direct current voltage measured by the direct current voltage measurement unit. Therefore, according to this impedance measurement device, in addition to the function of displaying a Cole-Cole plot and the function of generating display data for displaying a Cole-Cole plot, it is possible to generate display data for displaying at least one of the I-V characteristic graph and the I-P characteristic graph.

[0014] In addition, the impedance measurement device according to the present invention includes a direct current measurement unit. The direct current measurement unit measures the current value of the direct current when the direct current with the superimposed measurement alternating current inputs and outputs the measurement target. The processing unit acquires display data for displaying the I-Z characteristic graph on the display screen based on the current value of the direct current measured by the direct current measurement unit and the frequency characteristics of the complex impedance of the measurement target obtained. Therefore, according to this impedance measurement device, in addition to the function of displaying a Cole-Cole plot and the function of generating display data for displaying a Cole-Cole plot, it is possible to generate display data for displaying an I-Z characteristic graph.

[0015] In addition, the impedance measuring device according to the present invention includes an alternating current generation unit that generates the measurement alternating current and superimposes it on the direct current. Therefore, according to this impedance measuring device, it is possible to measure (calculate) the impedance of a measurement object that supplies a direct current to a load that cannot output a measurement alternating current, or a measurement object that is supplied with a direct current from a direct current power source that cannot output a measurement alternating current, and it is possible to display a characteristic graph and a Cole-Cole plot of the measurement object.

[0016] In addition, the impedance measuring device according to the present invention includes a non-contact current sensor that measures the current value of the direct current that inputs and outputs the measurement object. Therefore, according to this impedance measuring device, since it is possible to avoid contact of the internal mechanism of the current sensor with a power line or the like, it is possible to measure the current value of the direct current extremely safely.

[0017] In addition, the impedance measuring device according to the present invention, the current sensor is a clamp-type current sensor configured to be openable and closable. Therefore, according to this impedance measuring device, it is possible to reliably and quickly measure the current value of the direct current while the power line is connected between the measurement object and the load or the like.

[0018] In addition, the impedance measuring device according to the present invention includes a non-contact current sensor that measures the current value of the measurement alternating current flowing through the measurement object. Therefore, according to this impedance measuring device, since it is possible to avoid contact of the internal mechanism of the current sensor with a power line or the like, it is possible to measure the current value of the measurement alternating current extremely safely.

[0019] In addition, the impedance measuring device according to the present invention, the current sensor is a clamp-type current sensor configured to be openable and closable. Therefore, according to this impedance measuring device, it is possible to reliably and quickly measure the current value of the measurement alternating current while the power line is connected between the measurement object and the load or the like.

Advantages of the Invention

[0020] According to the display device, impedance measurement device, and display method according to the present invention, by selecting measurement points on the characteristic graph, it is possible to display in cooperation each measurement point on the characteristic graph and the Cole-Cole plot corresponding to each measurement point. Therefore, according to this display device, impedance measurement device, and display method, by displaying the characteristic graph and the Cole-Cole plot in cooperation, the user can accurately grasp the operating state and performance evaluation of the measurement object.

Brief Description of the Drawings

[0021]

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Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments of a display device, an impedance measurement device, and a display method will be described with reference to the accompanying drawings.

[0023] The impedance measurement device 1 shown in FIG. 1 is an example of an impedance measurement device that executes an impedance measurement method. It can measure the impedance of a fuel cell that generates power from supplied oxygen or hydrogen, a water electrolysis device (electrolysis device) that operates with a large direct current as a driving current to generate a large amount of hydrogen or oxygen, etc. as a measurement target. Further, the impedance measurement device 1 acquires an I-V characteristic graph (a characteristic graph showing the relationship between the voltage value of the input / output voltage and the current value of the input / output current) for the measurement target, an I-P characteristic graph (a characteristic graph showing the relationship between the power value of the input / output power and the current value of the input / output current), and an I-Z characteristic graph (a characteristic graph showing the relationship between the impedance of the measurement target DUT and the current value of the input / output current: hereinafter, when not distinguishing the three graphs, also referred to as the "characteristic graph"), and acquires a Cole-Cole plot corresponding to the measurement points of each characteristic graph. Further, the impedance measurement device 1 is configured to be able to display the acquired characteristic graph and Cole-Cole plot when grasping the operating state of the measurement target or evaluating the performance of the measurement target.

[0024] (First Embodiment) First, an example in which the fuel device is the measurement target DUT1 will be described. In this case, for the measurement target DUT1, the positive terminal T1 and the negative terminal T2 as a pair of input terminals are respectively connected to the positive input terminal and the negative input terminal of the load LD1 via a pair of power lines Lp, and supply (output) the direct current generated based on the supplied oxygen and hydrogen to the load LD1. Further, the load LD1 is composed of an electrical device or the like, consumes the direct current output from the measurement target DUT1, and is configured to be able to superimpose a sine-wave alternating current signal (measurement alternating current Im) used when measuring the impedance of the measurement target DUT1 on the direct current. Further, the load LD1 sweeps (changes) the frequency of the alternating current signal (measurement alternating current Im) and outputs it according to the frequency control signal Sf1 output from an external device (in this example, the processing unit 4 described later).

[0025] Next, the configuration of the impedance measuring device 1 will be described. As shown in FIG. 1, the impedance measuring device 1 includes a voltage measuring unit 2, a current sensor 3, a processing unit 4, a memory 5, an output unit 6, and voltage detection probes P1 and P2. Note that the processing unit 4, the memory 5, and the output unit 6 constitute a display device 10.

[0026] The voltage measuring unit 2 functions as a DC voltage measuring unit and an AC voltage measuring unit. Also, as shown in FIG. 1, the voltage measuring unit 2 is configured to be able to measure the voltage of a signal from DC to high frequency, and measures the voltage value of the input voltage V1 via a pair of probes P1 and P2 connected to the terminals T1 and T2 of the measurement target DUT, and outputs voltage value data Dv indicating the measured value (the voltage across the terminals T1 and T2) to the processing unit 4. In this case, when the measurement AC current Im flows through the measurement target DUT1, the voltage measuring unit 2 measures the voltage value of the AC voltage generated between the terminals T1 and T2 of the measurement target DUT1 due to the flow of the measurement AC current Im.

[0027] The current sensor 3 functions as a DC current measurement unit and an AC current measurement unit. Also, as the current sensor 3, for example, a current sensor as disclosed in Japanese Patent Application Laid-Open No. 2014-235045 can be used, and it is configured as a clamp-type ammeter capable of non-contact clamping of a wire such as a coated metal wire. Specifically, the current sensor 3 includes two semi-circular magnetic cores 3a and 3b, and a magnetic detection element 3c composed of, for example, a Hall element or a fluxgate element. By operating an operation unit (not shown) to bring the magnetic core 3a and the magnetic core 3b close to each other, an annular opening 3d can be formed to clamp (insert) a wire, and by operating the operation unit to separate the magnetic core 3a and the magnetic core 3b from each other, the clamp on the wire that has been clamped can be released (opened and closed), functioning as a clamp-type non-contact current sensor. Further, in this current sensor 3, the magnetic detection element 3c detects the magnetic flux generated in the magnetic cores 3a and 3b when a current flows through the wire inserted through the opening 3d, thereby measuring (detecting) the current value of the current in the frequency band from DC to high frequency flowing through the wire, and outputting current value data Di indicating the measured current value. However, as the current sensor 3, a configuration can be adopted in which two current sensors are used: a type of current sensor capable of measuring the current value of DC current and a type of sensor capable of measuring the current value of a high-frequency signal excluding DC. Also, as the current sensor 3, instead of a clamp-type current sensor, a current sensor configured with an annular core and not openable and closable can be adopted.

[0028] The processing unit 4 is composed of, for example, a CPU and comprehensively controls the impedance measuring device 1. Specifically, the processing unit 4 acquires the above-described three types of characteristic graphs and the call plot to be displayed in association with each characteristic graph (hereinafter also referred to as "displayed in cooperation"). Specifically, the processing unit 4 inputs and outputs the DUT1 via a pair of terminals T1 and T2 (output from the DUT1 in this example), and acquires display data Dd for displaying an I-V characteristic graph showing the characteristics of the voltage value of the DC voltage between the pair of terminals T1 and T2 with respect to the current value of the DC current, an I-P characteristic graph showing the characteristics of the power value of the power input and output via the pair of terminals T1 and T2 (output from the DUT1 in this example) with respect to the current value of the DC current input and output via the pair of terminals T1 and T2, and an I-Z characteristic graph showing the characteristics of the impedance of the DUT1 with respect to the current value of the DC current input and output via the pair of terminals T1 and T2 (output from the DUT1 in this example). At the same time, as will be described later, display data Dd for displaying the call plot is acquired.

[0029] In this case, the processing unit 4 obtains display data Dd for displaying an I-V characteristic graph or an I-P characteristic graph by acquiring each current value of the direct current output from the DUT1 to be measured measured by the current sensor 3 and each voltage value of the direct current voltage measured by the voltage measurement unit 2 when the direct current corresponding to each current value is output. Further, the processing unit 4 acquires each current value of the direct current output from the DUT1 to be measured measured by the current sensor 3 and a call plot for the DUT1 to be measured when the direct current corresponding to each current value is output, and associates each current value with the impedance (low-frequency resistance (LFR: Low Frequency Resistance: hereinafter also referred to as "LFR") or high-frequency resistance (HFR: High Frequency Resistance: hereinafter also referred to as "HFR")) in the call plot acquired at each current value, and obtains display data Dd for displaying an I-Z characteristic graph. Hereinafter, an example of displaying an I-Z characteristic graph using LFR as the impedance will be described, but an I-Z characteristic graph may also be displayed using HFR as the impedance.

[0030] Further, when acquiring the call plot, the processing unit 4 changes the frequency of the measurement alternating current Im by outputting the frequency control signal Sf1 to the load LD1 at each time point (measurement point) when the current value of the direct current output from the DUT1 to be measured changes. Then, when the measurement alternating current Im of each frequency is output, the processing unit 4 calculates the complex impedance of the DUT1 to be measured based on each voltage value of the alternating current voltage (the alternating current voltage generated between both ends of the terminals T1 and T2 in the DUT1 to be measured due to the flow of the measurement alternating current Im) measured by the voltage measurement unit 2 and each current value of the measurement alternating current Im measured by the current sensor 3. Further, the processing unit 4 obtains the frequency characteristic of the complex impedance of the DUT1 to be measured for displaying a call plot on the display screen of the output unit 6 based on the frequency of the measurement alternating current Im and the complex impedance calculated at that frequency.

[0031] Further, when performing impedance measurement, the processing unit 4 outputs a frequency control signal Sf1 to control the load LD1, superimpose the measurement AC current Im on the DC current while sweeping the frequency of the measurement AC current Im, and output it. Further, the processing unit 4 controls the voltage measurement unit 2 to measure the voltage between the probes P1 and P2 and output voltage value data Dv, and controls the current sensor 3 to measure the current flowing through the power line Lp (in this example, between the terminals T1 and T2) inserted through the opening 3d of the current sensor 3 and output current value data Di. Further, the processing unit 4 inputs the voltage value data Dv output from the voltage measurement unit 2 and the current value data Di output from the current sensor 3. Further, the processing unit 4 measures (calculates) the impedance of the measurement target DUT1 (the impedance between the terminals T1 and T2) based on the input voltage value data Dv and current value data Di.

[0032] Specifically, the processing unit 4 calculates the AC voltage (both-end voltage) between the terminals T1 and T2 of the measurement target DUT1 as the voltage value (V) based on the amplitude of the measurement AC current Im (AC voltage) included in the voltage value data Dv, and calculates the current value (I: supply current value) of the measurement AC current Im flowing through the measurement target DUT1 based on the amplitude of the AC current included in the current value data Di. Further, the processing unit 4 calculates the phase difference (θ) between the AC current and the AC voltage, that is, the phase difference (θ) between the AC voltage generated between the terminals T1 and T2 of the measurement target DUT1 and the AC current flowing through the measurement target DUT1, based on the voltage value data Dv and the current value data Di. Further, the processing unit 4 measures (calculates) the impedance of the measurement target DUT1 (impedance Z = V / I, R = Z·cosθ, X = Z·sinθ) based on the voltage value (V) of the AC voltage calculated in this way, the current value (I) of the measurement AC current Im, and the phase difference (θ).

[0033] Further, the processing unit 4 stores display data Dd for displaying the characteristic graph and the Cole-Cole plot of the DUT1 to be measured in the memory 5, and outputs the display data Dd in accordance with an instruction from an operation unit (not shown) to display the characteristic graph and the Cole-Cole plot on the display screen of the output unit 6. In this case, when one measurement point among a plurality of measurement points on one characteristic graph displayed on the display screen is selected, the processing unit 4 causes the Cole-Cole plot of the DUT1 when a direct current of the current value corresponding to the selected measurement point is being output to be displayed on the display screen of the output unit 6.

[0034] The memory 5 stores display data Dd for displaying the characteristic graph and the Cole-Cole plot of the DUT1 to be measured acquired by the processing unit 4. Specifically, when the fuel cell is the DUT1 to be measured, the memory 5 stores display data Dd for causing the acquired characteristic graph (for example, an I-V characteristic graph) to be displayed on the output unit 6 as shown in FIG. 5, and display data Dd for causing the Cole-Cole plot corresponding to four measurement points Po1 to Po4 (hereinafter also referred to as "measurement point Po" when not distinguishing including measurement points Po11 to Po14 described later) on the I-V characteristic graph to be displayed on the output unit 6 with the display content shown in FIGS. 6 to 9. Note that the Cole-Cole plot shown in FIG. 6 corresponds to the measurement point Po1, the Cole-Cole plot shown in FIG. 7 corresponds to the measurement point Po2, the Cole-Cole plot shown in FIG. 8 corresponds to the measurement point Po3, and the Cole-Cole plot shown in FIG. 9 corresponds to the measurement point Po4. In this case, actually, display data Dd of Cole-Cole plots corresponding to a large number of measurement points on the characteristic graph is stored in the memory 5, but for ease of understanding, an example of storing four Cole-Cole plots corresponding to four measurement points Po on the characteristic graph will be described. Further, when other devices such as an electrolytic device are the measurement targets, the memory 5 stores display data Dd for displaying an I-V characteristic graph, an I-P characteristic graph, an I-Z characteristic graph, and a Cole-Cole plot corresponding to the measurement target.

[0035] The output unit 6 is, for example, composed of a touch panel using a display device (display) such as a liquid crystal panel or an organic EL panel. It inputs the display data Dd output from the processing unit 4 and displays on the screen the impedance of the DUT 1 to be measured, the characteristic graph of the DUT 1 to be measured, and the call plot to be linked and displayed on each characteristic graph. Further, when a measurement point Po on the characteristic graph displayed on the touch panel is touched with a fingertip or the like, the output unit 6 outputs pointing data Dp to the processing unit 4. Note that instead of or in addition to touching the touch panel, a configuration may be adopted in which various pointing devices are used to point to the measurement point Po on the characteristic graph. Further, instead of the display device, the output unit 6 may be composed of an interface device that performs data communication with an external device, and by outputting the display data Dd, a configuration may be adopted in which the data is displayed on an external display device instead of the display by the output unit 6.

[0036] The probes P1 and P2 are contact-type probes for measuring the DC voltage output from the DUT 1 to be measured and the AC voltage as the voltage across the terminals T1 and T2 when the measurement AC current Im is output to the DUT 1 to be measured, with each tip connected (contacted) to the terminals T1 and T2 of the DUT 1 to be measured respectively.

[0037] Next, an impedance measurement method for measuring (calculating) the impedance of the DUT 1 to be measured using the impedance measurement device 1, an acquisition method for acquiring the characteristic graph and the call plot for the DUT 1 to be measured, and a display method for displaying the characteristic graph and the call plot on the output unit 6 will be described with reference to the drawings.

[0038] Note that the DUT 1 to be measured and the load LD1 have their respective positive electrodes and negative electrodes connected in advance via the power line Lp.

[0039] First, connect the probes P1 and P2 to the terminals T1 and T2 of the DUT1 to be measured. Also, clamp one of the pair of power lines Lp with the current sensor 3. In this case, since the current sensor 3 is non-contact type, a short circuit with the power line Lp can be avoided, and as a result, it can be safely attached to the power line Lp. Also, since the current sensor 3 is a clamp-type current sensor, it can be attached at any position on the power line Lp.

[0040] Next, operate a measurement start switch (not shown). At this time, the DC current generated by the DUT1 to be measured is supplied to the load LD1 via the power lines Lp, Lp. That is, the power line Lp is an active line through which a DC current flows. Then, the processing unit 4 outputs a frequency control signal Sf1 to control the load LD1, thereby superimposing the measurement AC current Im (AC voltage) on the DC current supplied from the DUT1 to be measured.

[0041] At this time, the voltage measurement unit 2 measures the voltage value (both-end voltage) of the voltage V1 generated between the terminals T1 and T2 of the DUT1 to be measured and outputs voltage value data Dv to the processing unit 4. Also, the current sensor 3 measures the current value of the current flowing through the power line Lp inserted (clamped) in the opening 3d. In this case, the current sensor 3 measures the current value of the DC current flowing through the power line Lp and the current value of the measurement AC current Im, and outputs current value data Di to the processing unit 4.

[0042] Next, the processing unit 4 inputs the voltage value data Dv output from the voltage measurement unit 2 and the current value data Di output from the current sensor 3. Further, based on the input voltage value data Dv and current value data Di, the processing unit 4 acquires the voltage value (output voltage with respect to the load LD1) and current value of the direct current output from the DUT 1 to be measured. As a result, the processing unit 4 acquires the current value at one measurement point (the measurement point at this time is referred to as "measurement point Po1") on the I-V characteristic graph when displayed as shown in FIG. 5 at the upper part of the display screen of the output unit 6, and the voltage value corresponding to the current value, thereby acquiring the display data Dd for displaying the I-V characteristic graph. After that, the processing unit 4 stores the acquired display data Dd in the memory 5. Further, at this current value, the processing unit 4 obtains the power value based on the current value and voltage value at the measurement point Po1 on the I-P characteristic graph when displayed as shown in FIG. 13 at the upper part of the display screen of the output unit 6, and acquires the current value of the direct current at the measurement point Po1 and the power value corresponding to the current value, thereby acquiring the display data Dd for displaying the I-P characteristic graph. After that, the processing unit 4 stores the acquired display data Dd in the memory 5.

[0043] Further, at the measurement point Po1, the processing unit 4 sweeps the frequency of the measurement AC current Im by outputting the frequency control signal Sf1 to the load LD1. At each frequency, based on the frequency of the measurement AC current Im, the voltage value of the voltage V1 measured by the voltage measurement unit 2 (input voltage value data Dv), and the current value of the measurement AC current Im measured by the current sensor 3 (input current value data Di), the processing unit 4 acquires the frequency characteristics of the complex impedance of the DUT1 under measurement. Thereby, the processing unit 4 acquires display data Dd for causing the call plot of the DUT1 under measurement at the measurement point Po1 of each characteristic graph to be displayed as shown in FIG. 6. Further, the processing unit 4 calculates the LFR in the acquired call plot (although the HFR may also be used, an example of calculating the LFR will be described as above), and acquires the current value of the DC current at the measurement point Po1 on the I-Z characteristic graph when displayed as shown in FIG. 15 at the upper part of the display screen of the output unit 6, and the LFR corresponding to the current value, thereby acquiring display data Dd for displaying the I-Z characteristic graph. Thereafter, the processing unit 4 stores the acquired display data Dd in the memory 5.

[0044] In FIG. 6, the arc drawn with a solid line indicates the call plot at the measurement point Po1, and the arc drawn with a broken line indicates the call plots at other measurement points Po2 to Po4 described later. However, in FIG. 6 and FIGS. 7 to 9 described later, the arcs drawn with broken lines corresponding to other measurement points can also be omitted from display. Also, in FIGS. 6 to 9, the black circles on the arc drawn with a solid line indicate the locations corresponding to the frequencies at which the impedance of the DUT1 under measurement was measured. In this case, actually, the impedance is measured at a large number of frequencies, but an example of measurement at several locations is shown for easy understanding. However, the display of this black circle can also be omitted.

[0045] Next, in the same manner as the above processing, the current sensor 3 measures the changed current value of the direct current flowing through the power line Lp and the current value of the measurement alternating current Im, and outputs current value data Di to the processing unit 4. Further, the voltage measurement unit 2 measures the direct current voltage value between the terminals T1 and T2 of the DUT 1 to be measured and the voltage value V1 of the alternating voltage, and outputs voltage value data Dv to the processing unit 4.

[0046] Next, the processing unit 4 obtains the current value at the measurement point Po2 on the I-V characteristic graph shown in FIG. 5 and the voltage value corresponding to the current value, thereby obtaining display data Dd for displaying the I-V characteristic graph and storing the obtained display data Dd in the memory 5. Further, in the same manner as the processing at the measurement point Po1, the processing unit 4 obtains the current value at the measurement point Po2 on the I-P characteristic graph shown in FIG. 13 and the power value corresponding to the current value, thereby obtaining display data Dd for displaying the I-P characteristic graph and storing the obtained display data Dd in the memory 5.

[0047] Also, at this measurement point Po2, the processing unit 4 outputs the frequency control signal Sf1 to the load LD1 in the same manner as the processing at the measurement point Po1, thereby sweeping the frequency of the measurement alternating current Im, and obtaining the frequency characteristics of the complex impedance of the DUT 1 to be measured at each frequency. Thereby, the processing unit 4 obtains display data Dd for displaying the Cole-Cole plot of the DUT 1 to be measured at the measurement point Po2 of each characteristic graph as shown in FIG. 7. Further, the processing unit 4 calculates the LFR in the obtained Cole-Cole plot, and obtains the current value of the direct current at the measurement point Po2 on the I-Z characteristic graph shown in FIG. 15 and the LFR corresponding to the current value, thereby obtaining display data Dd for displaying the I-Z characteristic graph. After that, the processing unit 4 stores the obtained display data Dd in the memory 5. In this case, in FIG. 7, the arc drawn with a solid line indicates the Cole-Cole plot at the measurement point Po2, and the arc drawn with a broken line indicates the Cole-Cole plots at the other measurement points Po1, Po3, and Po4.

[0048] Similarly, each time the current value of the direct current flowing through the power line Lp changes, the processing unit 4 executes the same processing as described above, thereby obtaining the current value at the measurement point Po3 on the I-V characteristic graph shown in FIG. 5 and the voltage value corresponding to the current value, and obtaining display data Dd for displaying the I-V characteristic graph and storing the obtained display data Dd in the memory 5. Similarly, the processing unit 4 obtains the current value at the measurement point Po3 on the I-P characteristic graph shown in FIG. 13 and the power value corresponding to the current value, and obtains display data Dd for displaying the I-P characteristic graph and stores the obtained display data Dd in the memory 5.

[0049] Also, in the process of processing the measurement point Po3, the processing unit 4 sweeps the frequency of the measurement alternating current Im by outputting the frequency control signal Sf1 to the load LD1 in the same manner as in the process of the measurement point Po1, and obtains the frequency characteristics of the complex impedance of the measurement object DUT1 at each frequency. Thereby, the processing unit 4 obtains display data Dd for displaying the Cole-Cole plot of the measurement object DUT1 at the measurement point Po3 on the characteristic graph as shown in FIG. 8. Further, the processing unit 4 calculates the LFR in the obtained Cole-Cole plot, and obtains the current value of the direct current at the measurement point Po3 on the I-Z characteristic graph shown in FIG. 15 and the LFR corresponding to the current value, thereby obtaining display data Dd for displaying the I-Z characteristic graph. Thereafter, the processing unit 4 stores the obtained display data Dd in the memory 5. In this case, in FIG. 8, the arc drawn by the solid line indicates the Cole-Cole plot at the measurement point Po3, and the arc drawn by the broken line indicates the Cole-Cole plots at the other measurement points Po1, Po2, and Po4.

[0050] Similarly, each time the current value of the direct current flowing through the power line Lp changes, the processing unit 4 executes the same processing as described above, and obtains the current value at the measurement point Po4 on the I-V characteristic graph shown in FIG. 5 and the voltage value corresponding to the current value, thereby obtaining display data Dd for displaying the I-V characteristic graph and storing the obtained display data Dd in the memory 5. Similarly, the processing unit 4 obtains the current value at the measurement point Po4 on the I-P characteristic graph shown in FIG. 13 and the power value corresponding to the current value, thereby obtaining display data Dd for displaying the I-P characteristic graph and storing the obtained display data Dd in the memory 5.

[0051] Further, in the process for the measurement point Po4, the processing unit 4 sweeps the frequency of the measurement AC current Im by outputting the frequency control signal Sf1 to the load LD1 in the same manner as in the process for the measurement point Po1, and obtains the frequency characteristics of the complex impedance of the DUT1 to be measured at each frequency. Thereby, the processing unit 4 obtains display data Dd for displaying the Cole-Cole plot of the DUT1 to be measured at the measurement point Po4 on the characteristic graph as shown in FIG. 9. Further, the processing unit 4 calculates the LFR in the obtained Cole-Cole plot, and obtains the current value of the direct current at the measurement point Po4 on the I-Z characteristic graph shown in FIG. 15 and the LFR corresponding to the current value, thereby obtaining display data Dd for displaying the I-Z characteristic graph. Thereafter, the processing unit 4 stores the obtained display data Dd in the memory 5. In this case, in FIG. 9, the arc drawn with a solid line indicates the Cole-Cole plot at the measurement point Po4, and the arc drawn with a broken line indicates the Cole-Cole plots at the other measurement points Po1 to Po3.

[0052] As described above, the memory 5 stores the display data Dd for the I-V characteristic graph shown in FIG. 5, the I-P characteristic graph shown in FIG. 13, the display data Dd for the I-Z characteristic graph shown in FIG. 15, and the display data Dd for the Cole-Cole plots at the measurement points Po1 to Po4 shown in FIGS. 6 to 9.

[0053] Next, the cooperative display process between the characteristic graph and the Cole-Cole plot by the impedance measuring device 1 will be described.

[0054] When causing the I-V characteristic graph as one characteristic graph and the Cole-Cole plot to be cooperatively displayed, the display of the I-V characteristic graph is instructed by an operation unit (not shown). At this time, the processing unit 4 reads out display data Dd for displaying the I-V characteristic graph from the memory 5 and outputs it to the output unit 6. As a result, as shown in FIG. 5, the output unit 6 displays the I-V characteristic graph. At this time, an image with the horizontal axis being the current value of the direct current and the vertical axis being the voltage value of the direct current is displayed on the output unit 6. Note that the black circles shown in the figure and the characters of the measurement points Po1 to Po4 corresponding to each black circle may be displayed or may not be displayed. The same applies to each figure described later.

[0055] In this case, in order to know at which measurement point (operating point) the optimal operating state of the measurement target DUT1 is, when discriminating using only the I-V characteristic graph, it is common to select a measurement point where the current value of the direct current is large and the voltage value is high. Therefore, generally, the user discriminates that it is preferable to operate the measurement target DUT1 at a measurement point between the measurement point Po2 and the measurement point Po3. However, if the water content of the electrolyte membrane in the measurement target DUT1, which is a fuel cell, is insufficient, if there is an excess or deficiency in the platinum catalyst used in the measurement target DUT1, or if there is an excess or deficiency in the oxygen or hydrogen supplied to the measurement target DUT1, it becomes difficult to operate the measurement target DUT1 in a state where the output efficiency is sufficient. For this reason, the measurement point selected simply because the current value of the direct current is large and the voltage value is high is not necessarily the measurement point indicating the optimal operating state.

[0056] Therefore, when any one of the plurality of measurement points Po1 to Po4 on the I-V characteristic graph is selected by a touch panel or a pointing device (assuming that the measurement point Po2 is selected at this time), the processing unit 4 inputs the pointing data Dp output from the output unit 6 to identify the measurement point Po, and reads out display data Dd for displaying the call plot of the DUT1 to be measured when a direct current of the current value corresponding to the selected measurement point Po2 is flowing, and outputs it to the output unit 6. At this time, as shown in FIG. 10, the output unit 6 displays the I-V characteristic graph at the upper part of the display screen, and displays the call plot of the DUT1 to be measured when a direct current of the current value corresponding to the measurement point Po2 is flowing at the lower part of the display screen.

[0057] In this case, in FIG. 10, call plots corresponding to other measurement points Po (in this example, measurement points Po1, Po3, Po4) are also displayed together, but it is also possible to make the call plots corresponding to other measurement points Po non-displayed. However, since it is possible to compare with the call plots corresponding to other measurement points Po, it is preferable to display the call plots corresponding to other measurement points Po together as well. Also, in the same figure, the processing unit 4 displays the call plot corresponding to the selected measurement point Po (in this example, measurement point Po2) with a thick line and the call plots corresponding to other measurement points Po with a thin line, and for the call plot corresponding to the selected measurement point Po2, black circles are displayed at positions corresponding to the frequency of the measurement AC current Im. However, it is not limited to this, as long as the call plot corresponding to the selected measurement point Po can be displayed in a manner that allows the user to grasp it. For example, the call plots corresponding to measurement points Po1 to Po4 can be displayed with lines of the same thickness, and only in the call plot corresponding to the selected measurement point Po2, black circles can be displayed at positions corresponding to the measured frequency of the measurement AC current Im. Also, without displaying black circles, only the call plot corresponding to the selected measurement point Po2 can be displayed with a thick line and the call plots corresponding to other measurement points Po with a thin line, and the call plot corresponding to the selected measurement point Po2 can be highlighted with respect to the call plots corresponding to other measurement points Po. Also, the call plot corresponding to the selected measurement point Po2 can be highlighted by displaying it in a display color different from that of the call plots corresponding to other measurement points Po. Note that in other characteristic graphs described later, it can be displayed in the same manner.

[0058] Accordingly, the user can grasp the operating state of the DUT1 under test by checking the Cole-Cole plot (frequency characteristics of complex impedance) of the DUT1 under test at any measurement point (in this example, measurement point Po2) on the I-V characteristic graph. In this case, in the Cole-Cole plot, the HFR shown in FIG. 12 corresponds to the length between the part with a value of 0 on the Z'-axis (real part of the complex impedance) and the part where it first intersects with the first semi-circle (also referred to as the "first semi-circle") on the side of the value 0 on the Z'-axis (also referred to as the "first intercept"). Also, the LFR corresponds to the length between the first intercept and the part (intercept) where it intersects on the side of infinity in value on the Z'-axis of the first semi-circle (or other semi-circles when other semi-circles are continuous with the first semi-circle). Also, on the Z'-axis, the resistance value corresponding to the length between the part with a value of 0 on the Z'-axis and the part (intercept) where the first semi-circle next intersects with the Z'-axis is defined as the resistance value R1.

[0059] In this case, in the DUT1 under test, the magnitude of the HFR represents the ease of electron conduction and ion conduction and is related to the water content in the electrolyte membrane. Also, the magnitude of the resistance value obtained by subtracting the HFR from the resistance value R1 represents the performance of the catalyst used in the DUT1 under test and is related to the excess or deficiency of the platinum catalyst in the DUT1 under test. Also, among the LFR, the magnitude of the resistance value obtained by adding the HFR to the resistance value obtained by subtracting the resistance value R1 represents the supply amount of the reactant and is related to the amount of oxygen and hydrogen supplied to the DUT1 under test. Therefore, in order to operate the DUT1 under test under optimal operating conditions, it is preferable that the HFR and LFR are small.

[0060] Therefore, by selecting another measurement point Po on the I-V characteristic graph, the user can find better operating conditions for the DUT1 under test. For this reason, for example, assume that the measurement point Po3 near the measurement point Po2 is selected. At this time, the processing unit 4 reads out the display data Dd for displaying the call plot of the DUT1 under test when a direct current corresponding to the current value of the selected measurement point Po3 is flowing, and outputs it to the output unit 6. At this time, as shown in FIG. 11, the output unit 6 displays the I-V characteristic graph at the upper part of the display screen, and displays the call plot of the DUT1 under test when a direct current corresponding to the current value of the measurement point Po3 on the I-V characteristic graph is flowing at the lower part of the display screen.

[0061] At this time, the user can grasp that the operating conditions of the DUT1 under test at the measurement point Po3 are better than those of the DUT1 under test at the measurement point Po2. Similarly, by checking the call plots corresponding to the measurement points Po1 and Po4, the user can grasp that the operating conditions of the DUT1 under test at the measurement point Po3 are the best operating conditions of the DUT1 under test.

[0062] Next, when the I-P characteristic graph and the call plot are to be displayed in cooperation as one characteristic graph, the display of the I-P characteristic graph is instructed by an operation unit (not shown). At this time, the processing unit 4 reads out the display data Dd for displaying the I-P characteristic graph from the memory 5 and outputs it to the output unit 6. As a result, as shown in FIG. 13, the output unit 6 displays the I-P characteristic graph. At this time, an image with the horizontal axis being the current value of the direct current and the vertical axis being the direct current power output from the DUT1 is displayed on the output unit 6.

[0063] In this case, when determining the optimal operating state of the DUT1 under test based only on the I-P characteristic graph to find out which measurement point (operating point) it is at, it is common to select a measurement point where the current value of the direct current is large and the power value is large. Therefore, generally, the user determines that it is preferable to operate the DUT1 under test at a measurement point between the measurement points Po3 and Po4. However, for the reasons described above, the measurement point selected simply because the current value of the direct current is large and the power value is large does not necessarily indicate the measurement point showing the optimal operating state.

[0064] Therefore, in the same manner as when the I-V characteristic graph and the call call plot are displayed in cooperation, when any one of the plurality of measurement points Po1 to Po4 on the I-P characteristic graph is selected by a touch panel or a pointing device (in this case, assuming that the measurement point Po4 is selected), the processing unit 4 reads out display data Dd for displaying the call call plot of the DUT1 under test when a direct current with a current value corresponding to the selected measurement point Po4 is flowing, and outputs it to the output unit 6. At this time, the output unit 6 displays the I-V characteristic graph at the upper part of the display screen, and displays the call call plot of the DUT1 under test when a direct current with a current value corresponding to the measurement point Po4 of the I-P characteristic graph is flowing at the lower part of the display screen.

[0065] Also, the user can find better operating conditions for the DUT1 under test by selecting other measurement points on the I-P characteristic graph. For this reason, for example, assuming that the measurement point Po3 near the measurement point Po4 is selected. At this time, the processing unit 4 reads out display data Dd for displaying the call call plot of the DUT1 under test when a direct current with a current value corresponding to the selected measurement point Po3 is flowing, and outputs it to the output unit 6. At this time, as shown in FIG. 14, the output unit 6 displays the I-P characteristic graph at the upper part of the display screen, and displays the call call plot of the DUT1 under test when a direct current with a current value corresponding to the measurement point Po3 of the I-P characteristic graph is flowing at the lower part of the display screen.

[0066] At this time, the user can understand that the operating conditions of the DUT1 to be measured at the measurement point Po3 are better than those of the DUT1 to be measured at the measurement point Po4. Similarly, by checking the call plots corresponding to the measurement points Po1 and Po2, the user can understand that the operating conditions of the DUT1 to be measured at the measurement point Po3 are the best operating conditions of the DUT1 to be measured.

[0067] Next, when the I-Z characteristic graph as one characteristic graph and the call plot are to be displayed in cooperation, the display of the I-Z characteristic graph is instructed by an operation unit (not shown). At this time, the processing unit 4 reads out the display data Dd for displaying the I-Z characteristic graph from the memory 5 and outputs it to the output unit 6. As a result, as shown in FIG. 15, the output unit 6 displays the I-Z characteristic graph at the upper part of the display screen. At this time, an image with the current value of the direct current as the horizontal axis and the LFR in the call plot of the DUT1 as the vertical axis is displayed on the output unit 6.

[0068] In this case, in order to know at which measurement point (operating point) the optimal operating state of the DUT1 to be measured is, when discriminating using only the I-Z characteristic graph, it is common to select a measurement point where the current value of the direct current is large and the impedance of the DUT1 is small. Therefore, generally, the user discriminates that it is preferable to operate the DUT1 to be measured at a measurement point between the measurement point Po3 and the measurement point Po4. However, for the reasons described above, the measurement point selected simply because the current value of the direct current is large and the impedance of the DUT1 is small is not necessarily the measurement point indicating the optimal operating state.

[0069] Therefore, in the same manner as when the I-V characteristic graph and the Cole-Cole plot are displayed in cooperation, when any one of the plurality of measurement points Po1 to Po4 on the I-Z characteristic graph is selected by a touch panel or a pointing device (in this case, it is assumed that the measurement point Po4 is selected), the processing unit 4 reads out display data Dd for displaying the Cole-Cole plot of the measurement target DUT1 when a direct current of the current value corresponding to the selected measurement point Po4 is flowing, and outputs it to the output unit 6. At this time, the output unit 6 displays the I-Z characteristic graph at the upper part of the display screen, and displays the Cole-Cole plot of the measurement target DUT1 when a direct current of the current value corresponding to the measurement point Po4 of the I-Z characteristic graph is flowing at the lower part of the display screen.

[0070] Also, the user can find better operating conditions of the measurement target DUT1 by selecting other measurement points on the I-Z characteristic graph. For this reason, for example, it is assumed that the measurement point Po3 near the measurement point Po4 is selected. At this time, the processing unit 4 reads out display data Dd for displaying the Cole-Cole plot of the measurement target DUT1 when a direct current of the current value corresponding to the selected measurement point Po3 is flowing, and outputs it to the output unit 6. At this time, as shown in FIG. 16, the output unit 6 displays the I-Z characteristic graph at the upper part of the display screen, and displays the Cole-Cole plot of the measurement target DUT1 when a direct current of the current value corresponding to the measurement point Po3 of the I-Z characteristic graph is flowing at the lower part of the display screen.

[0071] At this time, the user can grasp that the operating conditions of the measurement target DUT1 at the measurement point Po3 are superior to the operating conditions of the measurement target DUT1 at the measurement point Po4. Similarly, by checking the Cole-Cole plots corresponding to the measurement points Po1 and Po2, the user can grasp that the operating conditions of the measurement target DUT1 at the measurement point Po3 are the most excellent operating conditions of the measurement target DUT1.

[0072] In the above description, an example was described in which when one measurement point Po among the plurality of measurement points Po1 to Po4 on the characteristic graph displayed on the display screen was selected, the call plot of the DUT1 when a direct current of the current value corresponding to the selected measurement point Po was flowing was displayed on the display screen. However, the present invention is not limited to this. A plurality of call plots of the DUT1 when direct currents of current values respectively corresponding to a plurality of measurement points Po on the characteristic graph are flowing can be simultaneously displayed on the display screen, and when one measurement point Po among the plurality of measurement points Po on the characteristic graph displayed on the display screen is selected, a configuration can be adopted in which the call plot corresponding to the selected measurement point Po is highlighted. Hereinafter, the impedance measuring device 1 that performs this highlighting will be described. Note that since the configuration of the impedance measuring device 1 itself is the same as the above-described configuration, only different display processes will be described.

[0073] When the I-V characteristic graph as one characteristic graph and the call plot are to be displayed in cooperation, the cooperation display and the highlighting of the I-V characteristic graph and the call plot are instructed by an operation unit (not shown). At this time, the processing unit 4 reads out the display data Dd for displaying the I-V characteristic graph from the memory 5 and outputs it to the output unit 6, and simultaneously displays a plurality of call plots of the DUT1 when direct currents of current values respectively corresponding to a plurality of measurement points Po on the I-V characteristic graph are flowing on the display screen. As a result, as shown in FIG. 17, the output unit 6 displays the I-V characteristic graph at the upper part of the display screen and the call plot at the lower part of the display screen. In this case, as shown in the same figure, the processing unit 4 outputs the display data Dd and causes one call plot obtained by overlapping four call plots respectively corresponding to the measurement points Po1 to Po4 to be displayed at the lower part of the display screen of the output unit 6.

[0074] Next, when any one measurement point Po among a plurality of measurement points Po1 to Po4 on the I-V characteristic graph is selected by a touch panel or a pointing device (in this case, it is assumed that measurement point Po3 is selected), the processing unit 4 reads display data Dd for highlighting and displaying the call call plot of the measurement target DUT1 when a direct current of the current value corresponding to the selected measurement point Po3 is flowing so that it can be identified from other call call plots, and outputs the display data Dd to the output unit 6. At this time, as shown in FIG. 18, the output unit 6 displays the I-V characteristic graph at the upper part of the display screen, and highlights and displays the call call plot of the measurement target DUT1 when a direct current of the current value corresponding to the measurement point Po3 on the I-V characteristic graph is flowing, and displays it at the lower part of the screen.

[0075] In this case, in FIG. 18, as an example, the processing unit 4 displays the call call plot corresponding to the selected measurement point Po (in this example, measurement point Po3) with a thick line and the call call plots corresponding to other measurement points Po (in this example, measurement points Po1, Po2, Po4) with a thin line, and displays black circles at positions corresponding to the frequency of the measurement alternating current Im for the call call plot corresponding to the selected measurement point Po3. However, it is not limited to this, and the call call plots corresponding to the measurement points Po1 to Po4 can be displayed with lines of the same thickness, and black circles can be displayed only at positions corresponding to the frequency of the measured measurement alternating current Im for the call call plot corresponding to the selected measurement point Po. Also, without displaying black circles, only the call call plot corresponding to the selected measurement point Po3 can be displayed with a thick line and the call call plots corresponding to the other measurement points Po1, Po2, Po4 can be displayed with a thin line to highlight the call call plot corresponding to the selected measurement point Po.

[0076] Also, the user can find the most excellent operating conditions of the measurement target DUT1 by selecting other measurement points Po1, Po2, Po4 on the I-V characteristic graph in the same manner as the above-described operation.

[0077] Further, the processing unit 4 also executes the processing of the linked display of the I-P characteristic graph and the Cole-Cole plot, and the processing of the linked display of the I-Z characteristic graph and the Cole-Cole plot, in the same manner as the processing of the linked display of the I-V characteristic graph and the Cole-Cole plot.

[0078] In this way, in this display device 10, impedance measurement device 1, and display method by the display device 10, when one measurement point Po among a plurality of measurement points (in this example, measurement points Po1 to Po4) on one characteristic graph displayed on the display screen is selected, the Cole-Cole plot of the measurement object DUT1 (measurement object: in this example, a fuel cell) when a direct current of the current value corresponding to the selected measurement point Po is flowing is displayed on the display screen. Further, in this display device 10, impedance measurement device 1, and display method by the display device 10, a plurality of Cole-Cole plots of the measurement object DUT1 (measurement object: in this example, a fuel cell) when direct currents of the current values respectively corresponding to a plurality of measurement points (in this example, measurement points Po1 to Po4) on one characteristic graph displayed on the display screen are flowing are displayed on the display screen, and when one measurement point Po among a plurality of measurement points (in this example, measurement points Po1 to Po4) on one characteristic graph displayed on the display screen is selected, the Cole-Cole plot corresponding to the selected measurement point Po is highlighted and displayed on the display screen. In this case, in this display device 10, impedance measurement device 1, and display method by the display device 10, as the characteristic graph, an I-V characteristic graph, an I-P characteristic graph, and an I-Z characteristic graph are displayed.

[0079] Therefore, according to this display device 10, impedance measurement device 1, and display method by the display device 10, by selecting the measurement point Po in the characteristic graph, it is possible to display the linked display of each measurement point Po in the characteristic graph and the Cole-Cole plot corresponding to each measurement point Po.

[0080] Therefore, according to this display device 10, impedance measurement device 1, and the display method of the display device 10, by causing the characteristic graph and the Cole-Cole plot to be displayed in cooperation, the user can accurately grasp the operating state and performance evaluation of the DUT1 to be measured. Specifically, according to this display device 10, impedance measurement device 1, and the display method of the display device 10, the user can sequentially select each measurement point Po in the characteristic graph and sequentially check the corresponding Cole-Cole plot. At this time, by having the user check the magnitude of the HFR in the displayed Cole-Cole plot, the user can accurately grasp the operating state and performance evaluation of whether the water content of the electrolyte membrane in the DUT1 to be measured is appropriate when a direct current corresponding to the selected current value is flowing. Further, according to this display device 10, impedance measurement device 1, and the display method of the display device 10, by having the user check the magnitude of the resistance value obtained by subtracting the HFR from the resistance value R1 in the displayed Cole-Cole plot, the user can accurately grasp the operating state and performance evaluation of whether the amount of platinum catalyst used in the DUT1 to be measured is appropriate. Further, according to this display device 10, impedance measurement device 1, and the display method of the display device 10, by having the user check the magnitude of the resistance value obtained by adding the HFR to the resistance value obtained by subtracting the resistance value R1 from the LFR in the displayed Cole-Cole plot, the user can accurately grasp the operating state and performance evaluation of whether the amounts of oxygen and hydrogen supplied to the DUT1 to be measured are appropriate.

[0081] In addition, this impedance measuring device 1 includes a voltage measuring unit 2 (alternating current voltage measuring unit) and a current sensor 3 (alternating current measuring unit). The voltage measuring unit 2 measures the voltage value of the alternating current voltage generated across a pair of terminals (terminals T1, T2) due to the measurement alternating current Im flowing through the device under test DUT1. The current sensor 3 measures the current value of the measurement alternating current Im flowing through the device under test DUT1. The processing unit 4 acquires the frequency characteristics of the complex impedance of the device under test DUT1 for displaying a Cole-Cole plot on the display screen based on the frequency of the measurement alternating current Im, the voltage value of the alternating current voltage V1 measured by the voltage measuring unit 2, and the current value of the measurement alternating current Im measured by the current sensor 3 at each measurement point Po where the current value of the direct current changes. Therefore, according to this impedance measuring device 1, in addition to the function of displaying a Cole-Cole plot, display data Dd for displaying a Cole-Cole plot based on the frequency characteristics of the complex impedance of the device under test DUT1 can be generated.

[0082] Further, this impedance measuring device 1 includes a voltage measuring unit 2 (direct current voltage measuring unit) and a current sensor 3 (direct current measuring unit). When a direct current with the measurement alternating current Im superimposed thereon inputs and outputs the device under test DUT1 through a pair of terminals (terminals T1, T2) (in this example, "when outputting"), the voltage measuring unit 2 measures the voltage value of the direct current voltage generated across the pair of terminals (terminals T1, T2) with respect to the changed current value of the direct current. The current sensor 3 measures the current value of the direct current when a direct current with the measurement alternating current Im superimposed thereon inputs and outputs the device under test DUT1. The processing unit 4 acquires display data Dd for displaying a characteristic graph on the display screen based on the voltage value of the direct current voltage measured by the voltage measuring unit 2 and the current value of the direct current measured by the current sensor 3. Therefore, according to this impedance measuring device 1, in addition to the function of displaying a Cole-Cole plot and the function of generating display data Dd for displaying a Cole-Cole plot, display data Dd for displaying at least one of an I-V characteristic graph and an I-P characteristic graph can be generated.

[0083] Further, in this impedance measuring apparatus 1, a current sensor 3 (DC current measuring unit) is provided. When the DC current with the superimposed measurement AC current Im inputs and outputs the device under test DUT1 (in this example, "when outputting"), the current sensor 3 measures the current value of the DC current. The processing unit 4 acquires display data Dd for displaying an I-Z characteristic graph on the display screen based on the current value of the DC current measured by the voltage measuring unit 2 and the frequency characteristics of the complex impedance of the device under test DUT1 obtained. Therefore, according to this impedance measuring apparatus 1, in addition to the function of displaying a Cole-Cole plot and the function of generating display data Dd for displaying a Cole-Cole plot, display data Dd for displaying an I-Z characteristic graph can be generated.

[0084] Further, according to this impedance measuring apparatus 1, by providing the non-contact current sensor 3 that measures the current value of the DC current or the measurement AC current Im that inputs and outputs the device under test DUT1 (in this example, "outputs"), contact of the internal mechanism of the current sensor 3 with the power line Lp or the like can be avoided, so that the current value of the DC current can be measured extremely safely.

[0085] Further, according to this impedance measuring apparatus 1, since the current sensor 3 is a clamp-type current sensor configured to be openable and closable, the current values of the DC current and the measurement AC current Im can be reliably and quickly measured while the power line Lp is connected between the device under test DUT1 and the load LD1 or the like.

[0086] (Second Embodiment) Next, the configuration of the impedance measuring apparatus 1A will be described with reference to FIG. 2.

[0087] As shown in Fig. 2, impedance measurement device 1A is configured to include an AC current generation unit 7 that generates a measurement AC current Im in addition to the configuration of impedance measurement device 1. Therefore, in this impedance measurement device 1A, the impedance of the device under test DUT1 connected via the power line Lp to the load LD2 that does not have the function of outputting the measurement AC current Im can be measured. In this case, the load LD2 is composed of an electrical device or the like and consumes the DC current output from the device under test DUT1. Regarding the configuration of the impedance measurement device 1A and the impedance measurement devices 1B and 1C described later, the same configurations as those of the impedance measurement device 1 are denoted by the same reference numerals, and redundant descriptions are omitted.

[0088] The AC current generation unit 7 generates the measurement AC current Im according to the frequency control signal Sf2 output from the processing unit 4, and superimposes and outputs the generated measurement AC current Im on the DC current output from DUT1. In this case, the AC current generation unit 7 can also be configured as a general AC current source that can sweep (change) the frequency of the AC signal (measurement AC current Im) according to the frequency control signal Sf2 output from the processing unit 4. Further, the AC current generation unit 7 can be configured as an electronic load that consumes the DC power output from DUT1 as a load and outputs the measurement AC current Im at the indicated frequency according to the frequency control signal Sf2. Note that in the configuration of the AC current generation unit 7 using an electronic load, since the DC power output from the device under test DUT1 is consumed to generate the measurement AC current Im, a measurement AC current Im with a large current can be generated. Therefore, according to this impedance measurement device 1A, since the values of the calculated current value (I) and voltage value (V) can be increased, the impedance of the device under test DUT1 can be accurately measured (calculated).

[0089] Next, an impedance measurement method for measuring (calculating) the impedance of the DUT1 to be measured using the impedance measurement device 1A will be described. Note that, regarding the method for obtaining the characteristic graph and the Cole-Cole plot for the DUT1 to be measured, as well as the display method for displaying the characteristic graph and the Cole-Cole plot on the output unit 6, since they are the same as those of the impedance measurement device 1, differences will be explained and duplicate explanations will be omitted.

[0090] In this impedance measurement device 1A, when a measurement start switch (not shown) is operated, the direct current generated by the DUT1 to be measured is supplied to the load LD2 via the power lines Lp, Lp. Next, the processing unit 4 outputs a frequency control signal Sf2 to control the alternating current generation unit 7, thereby superimposing the measurement alternating current Im (alternating voltage) on the direct current supplied from the DUT1 to be measured. Next, the processing unit 4 executes the same processing as that of the impedance measurement device 1, and after obtaining the display data Dd for displaying the I-V characteristic graph, I-P characteristic graph, I-Z characteristic graph, and Cole-Cole plot, the obtained display data Dd is stored in the memory 5. After that, the processing unit 4 causes the characteristic graph and the Cole-Cole plot to be displayed on the display screen of the output unit 6 according to the operation instruction of the user.

[0091] Thus, according to this impedance measurement device 1A, in addition to the effects achieved by the impedance measurement device 1, by providing the alternating current generation unit 7 that generates the measurement alternating current Im and superimposes it on the direct current, it is possible to measure (calculate) the impedance of the DUT1 to be measured that supplies the direct current to the load LD2 that cannot output the measurement alternating current Im, and it is also possible to display the characteristic graph and the Cole-Cole plot of the DUT1 to be measured.

[0092] (Third Embodiment) Next, an impedance measurement device 1B with the electrolysis device as the device under test (DUT) 2 to be measured will be described. In this case, as shown in FIG. 3, for the DUT 2 to be measured, the positive terminal T11 and the negative terminal T12 as a pair of input terminals are respectively connected to the positive output terminal and the negative output terminal of the DC power supply PD1 via a pair of power lines Lp. The DUT 2 operates using the DC current supplied from the DC power supply PD1 as a driving current, and electrolyzes the supplied water to generate oxygen and hydrogen. Further, the DC power supply PD1 is configured to be able to superimpose a sine-wave AC signal (measurement AC current Im) used when measuring the impedance of the DUT 2 on the DC current while generating and outputting the DC current. Also, the DC power supply PD1 sweeps (changes) the frequency of the AC signal (measurement AC current Im) and outputs it according to the frequency control signal Sf3 output from an external device (in this example, the processing unit 4).

[0093] The processing unit 4 acquires display data Dd for displaying an I-V characteristic graph showing the characteristic of the DC voltage value between the pair of terminals T11 and T12 with respect to the current value of the DC current input to (in this example, input to) the DUT 2 via the pair of terminals T11 and T12, an I-P characteristic graph showing the characteristic of the power value of the power input to (in this example, input to) the DUT 2 via the pair of terminals T11 and T12 with respect to the current value of the DC current input to (in this example, input to) the DUT 2, and an I-Z characteristic graph showing the characteristic of the impedance of the DUT 2 with respect to the current value of the DC current input to (in this example, input to) the DUT 2 via the pair of terminals T11 and T12. At the same time, as described above, the processing unit 4 also acquires display data Dd for displaying a Cole-Cole plot.

[0094] Next, a display process for jointly displaying an I-V characteristic graph as one characteristic graph and a Cole-Cole plot will be described. Note that, since the method for acquiring the characteristic graph and the Cole-Cole plot for the DUT 2 to be measured and the display method for displaying the characteristic graph and the Cole-Cole plot on the output unit 6 are the same as those of the impedance measurement device 1, the differences will be described and the overlapping descriptions will be omitted.

[0095] In this impedance measuring device 1B, when a measurement start switch (not shown) is operated, a direct current generated by the direct current power supply PD1 is supplied to the device under test DUT2 via the power supply lines Lp, Lp. Next, the processing unit 4 outputs a frequency control signal Sf2 to control the direct current power supply PD1, thereby superimposing an alternating current Im (alternating voltage) for measurement on the supplied direct current. Next, the processing unit 4 executes the same processing as that of the impedance measuring device 1, and after acquiring display data Dd for displaying an I-V characteristic graph, an I-P characteristic graph, an I-Z characteristic graph, and a Cole-Cole plot, the acquired display data Dd is stored in the memory 5. After that, the processing unit 4 causes the output unit 6 to display a characteristic graph or a Cole-Cole plot on the display screen according to the operation instruction of the user.

[0096] In this case, when the characteristic graph of the acquired device under test DUT2 is displayed on the output unit 6, the I-V characteristic graph is displayed as shown in FIG. 19, the I-P characteristic graph is displayed as shown in FIG. 20, and the I-Z characteristic graph is displayed as shown in FIG. 21. Also, when the Cole-Cole plot of the acquired device under test DUT2 is displayed on the output unit 6, similar to the Cole-Cole plot of the device under test DUT1, for the Cole-Cole plot at the measurement point Po11 in each characteristic graph, it is displayed with the display content shown in FIG. 6, for the Cole-Cole plot at the measurement point Po12, it is displayed with the display content shown in FIG. 7, for the Cole-Cole plot at the measurement point Po13, it is displayed with the display content shown in FIG. 8, and for the Cole-Cole plot at the measurement point Po14, it is displayed with the display content shown in FIG. 9. Note that when a direct current with the same current value is flowing, the Cole-Cole plots of the devices under test DUT1 and DUT2 have substantially the same characteristic diagram.

[0097] In addition, in this impedance measuring device 1B, the user can accurately grasp the operating state and performance evaluation of the DUT 2 to be measured by the Cole-Cole plot. In this case, in the DUT 2 to be measured, the magnitude of the HFR represents the ease of electron conduction and ion conduction, and is related to the water content in the electrolyte membrane. Also, the magnitude of the resistance value obtained by subtracting the HFR from the resistance value R1 represents the performance of the catalyst used in the DUT 2 to be measured, and is related to the excess or deficiency of the platinum catalyst and iridium catalyst in the DUT 1 to be measured. Further, among the LFR, the magnitude of the resistance value obtained by adding the HFR to the resistance value obtained by subtracting the resistance value R1 represents the supply amount of the reactant, and is related to the amount of water supplied to the DUT 2 to be measured. Therefore, in order to operate the DUT 2 to be measured under optimal operating conditions, it is preferable that the HFR and LFR are small.

[0098] Also, when the characteristic graph and the Cole-Cole plot are displayed in cooperation, they are displayed in the same manner as the cooperative display in the impedance measuring device 1. As an example, when any one of the plurality of measurement points Po11 to Po14 on the I-V characteristic graph, for example, the measurement point Po, is selected by a touch panel or a pointing device (in this case, it is assumed that the measurement point Po13 is selected), the processing unit 4 reads out the display data Dd for displaying the Cole-Cole plot of the DUT 2 to be measured when a direct current of the current value corresponding to the selected measurement point Po13 is flowing, and outputs it to the output unit 6. At this time, as shown in FIG. 22, in the same manner as the cooperative display by the impedance measuring device 1, the output unit 6 displays the I-V characteristic graph at the upper part of the display screen, and at the lower part of the display screen, it displays the Cole-Cole plot for the DUT 2 to be measured when a direct current of the current value corresponding to the measurement point Po13 of the I-V characteristic graph is flowing.

[0099] When emphasizing the call - call plot, the processing unit 4 reads out display data Dd for displaying the characteristic graph from the memory 5 and outputs it to the output unit 6 in the same manner as the linked display and highlighting of the characteristic graph and the call - call plot in the impedance measuring device 1. At the same time, when direct - current of the current values corresponding to a plurality of measurement points Po11 to Po14 on the characteristic graph is flowing, a plurality of call - call plots of the DUT2 are simultaneously displayed on the display screen. Thereby, as shown in FIG. 23, the output unit 6 displays the characteristic graph at the upper part of the display screen and the call - call plot at the lower part of the display screen. In this case, the processing unit 4 outputs the display data Dd and causes one call - call plot obtained by overlapping four call - call plots respectively corresponding to the measurement points Po11 to Po14 to be displayed at the lower part of the display screen of the output unit 6.

[0100] Next, when, for example, any one of a plurality of measurement points on the I - V characteristic graph is selected by a touch panel or a pointing device (in this case, it is assumed that the measurement point Po13 is selected), the processing unit 4 reads out display data Dd for highlighting the call - call plot of the measurement target DUT2 when direct - current of the current value corresponding to the selected measurement point Po13 is flowing so that it can be identified from other call - call plots and outputs it to the output unit 6. At this time, as shown in FIG. 22, the output unit 6 displays the I - V characteristic graph at the upper part of the display screen and highlights the call - call plot of the measurement target DUT2 when direct - current of the current value corresponding to the measurement point Po13 of the I - V characteristic graph is flowing at the lower part of the screen.

[0101] Thus, in this display device 10, impedance measurement device 1B, and the display method by the display device 10, when one measurement point Po among a plurality of measurement points (in this example, measurement points Po11 to Po14) on one characteristic graph displayed on the display screen is selected, a call call plot of the DUT2 to be measured (measurement object: in this example, an electrolysis device) when a direct current of the current value corresponding to the selected measurement point Po is flowing is displayed on the display screen. Also, in this display device 10, impedance measurement device 1B, and the display method by the display device 10, when direct currents of current values respectively corresponding to a plurality of measurement points (in this example, measurement points Po1 to Po4) on one characteristic graph displayed on the display screen are flowing, a plurality of call call plots of the DUT2 to be measured (measurement object: in this example, an electrolysis device) are displayed on the display screen, and when one measurement point Po among a plurality of measurement points (in this example, measurement points Po11 to Po14) on one characteristic graph displayed on the display screen is selected, the call call plot corresponding to the selected measurement point Po is highlighted on the display screen. In this case, in this display device 10, impedance measurement device 1B, and the display method by the display device 10, as the characteristic graph, an I-V characteristic graph, an I-P characteristic graph, and an I-Z characteristic graph are displayed.

[0102] Therefore, according to this display device 10, impedance measurement device 1B, and the display method by the display device 10, by allowing the measurement point Po in the characteristic graph to be selected, it is possible to display in cooperation each measurement point Po in the characteristic graph and the call call plot corresponding to each measurement point Po.

[0103] Therefore, according to this display device 10, impedance measurement device 1B, and the display method of the display device 10, by causing the characteristic graph and the Cole-Cole plot to be displayed in cooperation, the user can accurately grasp the operating state and performance evaluation of the measurement target DUT2. Specifically, according to this display device 10, impedance measurement device 1B, and the display method of the display device 10, for the user, each measurement point Po in the characteristic graph is sequentially selected, and the corresponding Cole-Cole plot is sequentially confirmed. At this time, by having the user confirm the magnitude of the HFR in the displayed Cole-Cole plot, the user can accurately grasp the operating state and performance evaluation of whether the water content of the electrolyte membrane in the measurement target DUT2 is appropriate in the state where the DC current of the selected current value is flowing. Also, according to this display device 10, impedance measurement device 1, and the display method of the display device 10, for the user, by having the user confirm the magnitude of the resistance value obtained by subtracting the HFR from the resistance value R1 in the displayed Cole-Cole plot, the user can accurately grasp the operating state and performance evaluation of whether the amount of platinum catalyst or iridium catalyst used in the measurement target DUT2 is appropriate. Also, according to this display device 10, impedance measurement device 1, and the display method of the display device 10, for the user, by having the user confirm the magnitude of the resistance value obtained by adding the HFR to the resistance value obtained by subtracting the resistance value R1 from the LFR in the displayed Cole-Cole plot, the user can accurately grasp the operating state and performance evaluation of whether the amount of water supplied to the measurement target DUT2 is appropriate.

[0104] Also, according to this impedance measurement device 1B, the same effects as those of the impedance measurement device 1 can be achieved.

[0105] (Fourth Embodiment) Next, the configuration of the impedance measurement device 1C will be described with reference to FIG. 4.

[0106] As shown in Fig. 4, impedance measurement device 1C is configured to include an alternating current generation unit 7 that generates a measurement alternating current Im in addition to the configuration of impedance measurement device 1B. Therefore, in this impedance measurement device 1C, the impedance of the DUT2 to be measured, which is connected to the direct current power supply PD2 without the function of outputting the measurement alternating current Im via the power line Lp, can be measured. Regarding the configuration of the impedance measurement device 1C, the same configurations as those of the impedance measurement devices 1, 1A, and 1B are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0107] Next, an impedance measurement method for measuring (calculating) the impedance of the DUT2 to be measured using the impedance measurement device 1C will be described. Regarding the method for obtaining the characteristic graph and the Cole-Cole plot of the DUT2 to be measured, and the display method for displaying the characteristic graph and the Cole-Cole plot on the output unit 6, since they are the same as those of the impedance measurement device 1, the differences will be described and duplicate descriptions will be omitted.

[0108] In this impedance measurement device 1C, when a measurement start switch (not shown) is operated, the direct current generated by the direct current power supply PD2 is supplied to the DUT2 to be measured via the power lines Lp, Lp. Next, the processing unit 4 outputs a frequency control signal Sf4 to control the alternating current generation unit 7, thereby superimposing the measurement alternating current Im (alternating voltage) on the direct current supplied from the direct current power supply PD2. Next, the processing unit 4 executes the same processing as that of the impedance measurement device 1, and after obtaining the display data Dd for displaying the I-V characteristic graph, the I-P characteristic graph, the I-Z characteristic graph, and the Cole-Cole plot, the obtained display data Dd is stored in the memory 5. After that, the processing unit 4 causes the characteristic graph and the Cole-Cole plot to be displayed on the display screen of the output unit 6 according to the operation instruction of the user.

[0109] Thus, according to this impedance measuring device 1C, in addition to the effects achieved by the impedance measuring device 1B, by including an alternating current generating unit 7 that generates a measurement alternating current Im and superimposes it on a direct current, it is possible to measure (calculate) the impedance of a measurement target DUT2 supplied with a direct current from a direct current power supply PD2 that cannot output the measurement alternating current Im, and it is also possible to display the characteristic graph and the Cole-Cole plot of the measurement target DUT2.

[0110] Note that the present invention is not limited to the configurations of the impedance measuring devices 1, 1A to 1C described above and can be changed as appropriate. For example, when a direct current corresponding to the current value corresponding to each of a plurality of measurement points Po on one characteristic graph displayed on the display screen is flowing, the Cole-Cole plots of the measurement target DUT1 (or the measurement target DUT2) are superimposed and a plurality of them are displayed on the display screen. When one of the plurality of measurement points Po on one characteristic graph displayed on the display screen is selected, an example of highlighting in which the Cole-Cole plot corresponding to the selected measurement point Po is highlighted on the display screen has been described, but the present invention is not limited to this. The Cole-Cole plots of the measurement target DUT1 (or the measurement target DUT2) when a direct current corresponding to the current value corresponding to each of a plurality of measurement points Po on one characteristic graph displayed on the display screen is flowing are displayed on the display screen without being superimposed, and when one of the plurality of measurement points Po on one characteristic graph is selected, as described above, it can also be highlighted so as to be distinguishable from the Cole-Cole plots corresponding to the other unselected measurement points Po. Also, in that case, the Cole-Cole plots corresponding to the other measurement points Po can be made non-displayed. Further, as long as the Cole-Cole plot corresponding to the selected measurement point Po is displayed so as to be distinguishable from the Cole-Cole plots corresponding to the other measurement points Po, for example, a configuration can be adopted in which it is highlighted with a different display color or line type (such as a solid line and a broken line) from the other Cole-Cole plots.

[0111] In addition, in the above-described embodiments, an example has been described in which all three of the I-V characteristic graph, the I-P characteristic graph, and the I-Z characteristic graph can be displayed. However, the present invention is not limited to this. It is also possible to adopt a configuration in which any one or two of the I-V characteristic graph, the I-P characteristic graph, and the I-Z characteristic graph are displayed in cooperation with a call plot on the one or two characteristic graphs.

[0112] In addition, in the above-described embodiments, the characteristic graph is displayed at the upper part of the display screen of the output unit 6, and the call plot is displayed at the lower part of the display screen of the output unit 6. However, the display mode is not limited to this and can be changed as appropriate. For example, the characteristic graph may be displayed at the lower part of the display screen of the output unit 6, and the call plot may be displayed at the upper part of the display screen of the output unit 6. Also, the characteristic graph may be displayed on either the left or right side of the display screen of the output unit 6, and the call plot may be displayed on the other side of the left and right of the display screen of the output unit 6.

[0113] In addition, for example, an example using the open / closed and clamp-type current sensors 3a and 3b has been described. However, a current sensor of a type fixedly attached to the power line Lp can also be used, or a shunt resistor can also be used.

[0114] In addition, an example has been described in which the voltage measurement unit 2 and the current sensor 3 output data (voltage value data Dv and current value data Di). However, the voltage measurement unit 2 outputs a voltage detection signal that is an analog signal, and the current sensor 3 outputs a current detection signal that is an analog signal, and a configuration can be adopted in which the processing unit 4 measures (calculates) the impedance by digital processing based on the input voltage detection signal and current detection signal. Similarly, a configuration can be adopted in which either the voltage measurement unit 2 or the current sensor 3 outputs a detection signal that is an analog signal, and the processing unit 4 measures (calculates) the impedance by digital processing based on the input detection signal that is an analog signal and digital data.

Industrial Applicability

[0115] According to the invention of the present application, by causing the characteristic graph and the call plot to be displayed in cooperation, the user can accurately grasp the operating state and performance evaluation of the measurement target. As a result, the invention of the present application can be widely applied to such a display device, impedance measurement device, and display method.

Explanation of Reference Numerals

[0116] 1, 1A to 1C Impedance Measurement Device 2 Voltage Measurement Unit 3 Current Sensor 4 Processing Unit 5 Memory 6 Output Unit 7 Alternating Current Generation Unit Dv Voltage Value Data Di Current Value Data DUT1, DUT2 Measurement Target

Claims

1. A display device including a processing unit that causes a display screen to display at least one characteristic graph among a current-voltage characteristic graph showing the characteristic of the voltage value of the DC voltage between a pair of terminals with respect to the current value of the DC current for inputting and outputting a measurement object via the pair of terminals, a current-power characteristic graph showing the characteristic of the power value of the power input and output via the pair of terminals with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, and a current-impedance characteristic graph showing the characteristic of the impedance of the measurement object with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, wherein when one measurement point among a plurality of measurement points on the one characteristic graph displayed on the display screen is selected, the processing unit causes the display screen to display a call plot of the measurement object when the DC current corresponding to the current value of the selected measurement point is flowing.

2. A display device including a processing unit that causes a display screen to display at least one characteristic graph among a current-voltage characteristic graph showing the characteristic of the voltage value of the DC voltage between a pair of terminals with respect to the current value of the DC current for inputting and outputting a measurement object via the pair of terminals, a current-power characteristic graph showing the characteristic of the power value of the power input and output via the pair of terminals with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, and a current-impedance characteristic graph showing the characteristic of the impedance of the measurement object with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, wherein the processing unit causes a plurality of call plots of the measurement object when the DC current corresponding to the current value corresponding to each of the plurality of measurement points on the one characteristic graph is flowing to be displayed on the display screen, and when one of the plurality of measurement points on the one characteristic graph displayed on the display screen is selected, the processing unit highlights the call plot corresponding to the selected measurement point.

3. The display device according to claim 1, wherein the one graph is a current-voltage characteristic graph.

4. The display device according to claim 1, wherein the one graph is a current-power characteristic graph.

5. The display device according to claim 1, wherein the one graph is a current-impedance characteristic graph.

6. The display device according to claim 2, wherein the one graph is a current-voltage characteristic graph.

7. The display device according to claim 2, wherein the one graph is a current-power characteristic graph.

8. The display device according to claim 2, wherein the one graph is a current-impedance characteristic graph.

9. A display device according to any one of claims 1 to 8, comprising an AC voltage measurement unit and an AC current measurement unit, wherein the AC voltage measurement unit measures a voltage value of an AC voltage generated between both ends of the pair of terminals due to the measurement AC current flowing through the measurement object, the AC current measurement unit measures a current value of the measurement AC current flowing through the measurement object, and the processing unit, at each measurement point where the current value of the DC current has changed, based on the frequency of the measurement AC current, the voltage value of the AC voltage measured by the AC voltage measurement unit, and the current value of the measurement AC current measured by the AC current measurement unit, obtains a frequency characteristic of the complex impedance of the measurement object for displaying the call plot on the display screen. An impedance measurement device.

10. Comprising a DC voltage measurement unit and a DC current measurement unit, wherein the DC voltage measurement unit measures a voltage value of the DC voltage generated between both ends of the pair of terminals with respect to the changed current value of the DC current when the DC current superimposed with the measurement AC current inputs and outputs the measurement object through the pair of terminals, the DC current measurement unit measures a current value of the DC current when the DC current superimposed with the measurement AC current inputs and outputs the measurement object, and the processing unit obtains display data for displaying at least one of the I-V characteristic graph and the I-P characteristic graph on the display screen based on the voltage value of the DC voltage measured by the DC voltage measurement unit and the current value of the DC current measured by the DC current measurement unit. The impedance measurement device according to claim 9.

11. Comprising a DC current measurement unit, wherein the DC current measurement unit measures a current value of the DC current when the DC current superimposed with the measurement AC current inputs and outputs the measurement object. The impedance measuring device according to claim 9, wherein the processing unit acquires display data for causing the display screen to display the I-Z characteristic graph based on the current value of the direct current measured by the direct current measuring unit and the frequency characteristics of the complex impedance of the measurement object acquired.

12. The impedance measuring device according to claim 9, further comprising an alternating current generating unit that generates the measurement alternating current and superimposes it on the direct current.

13. The impedance measuring device according to claim 9, further comprising a non-contact current sensor that measures the current value of the direct current for inputting and outputting the measurement object.

14. The impedance measuring device according to claim 13, wherein the current sensor is a clamp-type current sensor configured to be openable and closable.

15. The impedance measuring device according to claim 9, further comprising a non-contact current sensor that measures the current value of the measurement alternating current flowing through the measurement object.

16. The impedance measuring device according to claim 15, wherein the current sensor is a clamp-type current sensor configured to be openable and closable.

17. A current-voltage characteristic graph showing the characteristic of the voltage value of the direct current voltage between the pair of terminals with respect to the current value of the direct current for inputting and outputting the measurement object via the pair of terminals, a current-power characteristic graph showing the characteristic of the power value of the power input and output via the pair of terminals with respect to the current value of the direct current for inputting and outputting the measurement object via the pair of terminals, and a current-impedance characteristic graph showing the characteristic of the impedance of the measurement object with respect to the current value of the direct current for inputting and outputting the measurement object via the pair of terminals, and at least one of the characteristic graphs is displayed on the display screen. A display method, A display method in which when one of a plurality of measurement points on the one characteristic graph displayed on the display screen is selected, a call plot of the measurement object when the direct current of the current value corresponding to the selected measurement point is flowing is displayed on the display screen.

18. A display method for displaying on a display screen at least one characteristic graph among a current-voltage characteristic graph showing the characteristic of the voltage value of the DC voltage between a pair of terminals with respect to the current value of the DC current for inputting and outputting a measurement object via the pair of terminals, a current-power characteristic graph showing the characteristic of the power value of the power input and output via the pair of terminals with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, and a current-impedance characteristic graph showing the characteristic of the impedance of the measurement object with respect to the current value of the DC current for inputting and outputting the measurement object via the pair of terminals, displaying a plurality of call call plots of the measurement object when the DC current of the current value corresponding to a plurality of measurement points on the one characteristic graph is flowing on the display screen, and when one of the plurality of measurement points on the one characteristic graph displayed on the display screen is selected, highlighting the call call plot corresponding to the selected measurement point.

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