JP5483155B2 - Electrochemical reaction measuring method and electrochemical reaction measuring device - Google Patents

Description

  The present invention relates to an electrochemical reaction measurement method and an electrochemical reaction measurement apparatus that give a perturbation signal to an object to be measured and perform measurement related to an electrochemical reaction of the object to be measured based on a response signal.

  As a method for measuring the impedance of a fuel cell or other cell, a method is known in which a perturbation signal is given to the cell and the impedance is calculated based on the response signal at that time. In this method, power is generated at a certain operating point (output current Idc, output voltage Vdc), AC current perturbation Iac of frequency f1 is superimposed, voltage response signal Vac is obtained, and impedance at frequency f1 is calculated. . Alternatively, the AC voltage perturbation Vac having the frequency f1 is superimposed at the operating point, the current response signal Iac is obtained, and the impedance at the frequency f1 is calculated. For example, when impedance measurement is required in a state where the remaining capacity (SOC; State of Charge) is uniform in a secondary battery or the like, the output current Idc is set to zero after setting the SOC of the battery to a desired state ( Alternatively, AC perturbation is applied with the output voltage Vdc fixed, and the impedance is measured based on the response signal at that time.

  In general, electrochemical reactions are considered to be nonlinear reactions. For impedance measurement, the perturbation voltage width or perturbation current width of alternating current is reduced, so that there is no problem even if the system is linearly approximated, that is, errors are allowed. The measurement is performed in the area where it is performed.

JP 2007-250365 A

  However, there is no agreement on the conditions for linear approximation of nonlinear phenomena, and the perturbation voltage width or perturbation current width is made as small as possible, or a predetermined perturbation voltage value or perturbation current value is applied. The signal width of such a perturbation signal has not been studied.

  In addition, no method has been proposed in which the degree of waveform distortion of the response signal caused by the nonlinear reaction is used for the analysis of the electrochemical reaction.

  An object of the present invention is to provide an electrochemical reaction measurement method and an electrochemical reaction measurement apparatus capable of performing detailed measurement relating to an electrochemical reaction by utilizing a phenomenon caused by the nonlinear reaction and the degree of the nonlinear reaction.

The electrochemical reaction measurement method of the present invention is the electrochemical reaction measurement method in which a perturbation signal is given to an object to be measured, and measurement related to the electrochemical reaction of the object to be measured is performed based on a response signal, and the amplitude of the perturbation signal is changed. And obtaining a response signal corresponding to the amplitude of the perturbation signal that changes due to the step of changing the amplitude;
Based on the response signal acquired by the step of acquiring the response signal, acquiring the amplitude of the perturbation signal in which nonlinearity of the impedance of the measurement object appears;
It is characterized by providing.
According to this electrochemical reaction measurement method, the amplitude of the perturbation signal is changed, and a response signal corresponding to the amplitude of the perturbation signal is acquired, so measurement using the phenomenon caused by the nonlinear reaction and the degree of the nonlinear reaction is possible. It becomes.

  You may provide the step which calculates the impedance of the said to-be-measured object according to the amplitude of the said perturbation signal based on the response signal acquired by the step which acquires the said response signal.

  You may provide the step which calculates the frequency spectrum of the response signal acquired by the step which acquires the said response signal.

  The frequency spectrum may be an amplitude spectrum or a phase spectrum of the response signal obtained by obtaining the response signal.

The electrochemical reaction measuring device according to the present invention provides a perturbation signal to an object to be measured, and changes an amplitude of the perturbation signal in an electrochemical reaction measuring device that performs measurement related to an electrochemical reaction of the object to be measured based on a response signal. Based on the response signal acquired by the response signal acquiring means, the response signal acquiring means for acquiring the response signal according to the amplitude of the perturbation signal changed by the amplitude control means, and the measured signal Amplitude acquisition means for acquiring the amplitude of the perturbation signal in which the nonlinearity of the impedance appears .
According to this electrochemical reaction measurement device, the amplitude of the perturbation signal is changed, and a response signal corresponding to the amplitude of the perturbation signal is acquired, so that measurement using the phenomenon caused by the non-linear reaction and the degree of the non-linear reaction is possible. It becomes.

  According to the electrochemical reaction measurement method of the present invention, the amplitude of the perturbation signal is changed and a response signal corresponding to the amplitude of the perturbation signal is acquired. Therefore, measurement using the phenomenon caused by the non-linear reaction and the degree of the non-linear reaction Is possible.

  According to the electrochemical reaction measurement device of the present invention, the amplitude of the perturbation signal is changed, and a response signal corresponding to the amplitude of the perturbation signal is acquired. Therefore, the measurement using the phenomenon caused by the non-linear reaction and the degree of the non-linear reaction Is possible.

The block diagram which shows the structure of the measuring device for performing the electrochemical reaction measuring method by this invention. The flowchart which shows operation | movement of a measuring device. The figure which illustrates the correspondence of the amplitude and impedance of a perturbation signal.

  Hereinafter, embodiments of the electrochemical reaction measurement method according to the present invention will be described.

  FIG. 1 is a block diagram showing a configuration of a measuring apparatus for performing an electrochemical reaction measuring method according to the present invention.

  As shown in FIG. 1, an electronic load 2 is connected to a battery 1 as an object to be measured, and a predetermined operating point is given to the battery 1 through the electronic load 2, and an operating voltage or operating current at the operating point is given. Is superimposed with a perturbation signal (voltage perturbation signal or current perturbation signal).

  As shown in FIG. 1, the measuring device 3 includes an amplitude control unit 31 that controls the electronic load 2 and a response signal acquisition unit 32 that acquires a response signal of the battery 1. In addition, the measuring device 3 is provided with a calculation unit 33 that executes a calculation based on the response signal acquired by the response signal acquisition unit 32 and a display unit 34 that displays a calculation result in the calculation unit 33.

  FIG. 2 is a flowchart showing the operation of the measuring device 3.

  In step S1 of FIG. 2, measurement conditions are set based on a user instruction. The setting parameters set here include the frequency of the perturbation signal, the initial value of the amplitude of the perturbation signal, the upper limit value of the amplitude of the perturbation signal, the change width of the amplitude of the perturbation signal, and the like. Further, when the battery 1 is a fuel cell, etc., a DC load (output voltage value or output current value) is set, and when the battery 1 is a secondary battery, a remaining capacity (SOC; State of Charge) is set. Set as a parameter.

  Next, in step S2, the amplitude control means 31 applies a DC load to the battery 1 via the electronic load 2 and superimposes a perturbation signal on the DC load in accordance with the set parameters. The amplitude of the perturbation signal at the start of measurement follows the initial value of the amplitude of the perturbation signal in the setting parameter.

  Next, in step S <b> 3, the response signal of the battery 1 is acquired by the response signal acquisition unit 32.

  Next, in step S4, the calculation unit 32 calculates the impedance of the battery 1. Here, based on the response signal acquired by the response signal acquisition means 32, the impedance (Z, θ) of the battery 1 is calculated, and the calculation result is stored in association with the amplitude of the perturbation signal. Since the method for calculating the impedance by comparing the perturbation signal and the response signal is known, the description of the impedance calculation method is omitted.

  Next, in step S5, it is determined whether or not the amplitude of the perturbation signal has reached the upper limit value of the amplitude of the perturbation signal in the setting parameter. If the determination is affirmed, the process proceeds to step S7, and if the determination is negative, step S7 is performed. Proceed to S6.

  In step S6, the amplitude of the perturbation signal is increased by the change width of the amplitude of the perturbation signal in the setting parameter, and the process proceeds to step S2.

  In step S7, the calculation unit 33 calculates the correspondence between the amplitude of the perturbation signal and the impedance based on the stored calculation result of the impedance (Z, θ) of the battery 1.

  FIG. 3 is a diagram illustrating a correspondence relationship between the amplitude of the perturbation signal and the impedance calculated by the calculation unit 33. As shown in FIG. 3, the initial value of the amplitude of the perturbation signal is in the linear region, and the impedance (Z, θ) is correctly calculated. Furthermore, even if the amplitude of the perturbation signal is increased, the calculated impedance (Z, θ) does not change in the linear region. However, when the amplitude of the perturbation signal reaches the limit amplitude, it enters a non-linear region, the linearity is lost, and the calculated apparent Z and θ increase.

  For this reason, the threshold value (limit amplitude) at which the linearity is lost can be grasped by referring to the change state of Z and θ. For example, by displaying the calculation result in the calculation unit 33 on the display unit 34 as a graph as shown in FIG. 3, the user can easily grasp the threshold value (limit amplitude).

  As described above, in the above embodiment, the threshold value (limit amplitude) for switching from the linear region to the nonlinear region is clarified. Therefore, by increasing the perturbation amplitude as much as possible within the range in which the linearity is maintained, the SN at the time of impedance measurement is obtained. The ratio can be improved. For example, the impedance calculated by the measurement immediately before reaching the threshold (limit amplitude) can be adopted as the measurement value. Further, by performing preliminary measurement on a new object to be measured according to the procedure shown in FIG. 2, the amplitude of the perturbation signal suitable for impedance measurement can be determined in advance.

  In addition, it is possible to perform highly sensitive measurement of deterioration or state change of the measurement object using the relationship between the amplitude of the perturbation signal and impedance. For example, since the threshold value (limit amplitude) is predicted to decrease when deterioration occurs, the degree of deterioration can be estimated by grasping the change state of the threshold value (limit amplitude). On the other hand, since the amplitude of the perturbation signal is minimized in the conventional impedance measurement, the deterioration is not reflected in the calculated impedance value until the deterioration is greatly advanced, and the deterioration state cannot be known at an early stage.

  Spectral analysis may be performed instead of or in parallel with the evaluation based on the correspondence between the amplitude of the perturbation signal and the impedance (FIG. 3).

  For example, the frequency spectrum of the response signal corresponding to the perturbation signal can be calculated by the calculation unit 33 and displayed on the display unit 34. In this case, the frequency spectrum does not lead to the measured impedance value, but by calculating the frequency spectrum of the response signal with the frequency of the perturbation signal as the fundamental frequency, the frequency spectrum breakdown (detailed situation of distortion) is grasped in detail. It becomes possible to do. As the frequency spectrum in this case, in addition to the amplitude ratio with respect to the fundamental frequency, the frequency characteristic of the phase with respect to the fundamental spectrum (the phase difference of the response signal with respect to the perturbation signal) can also be obtained.

  The scope of application of the present invention is not limited to the above embodiment. The present invention can be widely applied to an electrochemical reaction measurement method and an electrochemical reaction measurement device that give a perturbation signal to an object to be measured and perform measurement related to an electrochemical reaction of the object to be measured based on a response signal.

31 Amplitude control means 32 Response signal acquisition means

Claims (5)

In an electrochemical reaction measurement method that gives a perturbation signal to an object to be measured and performs measurement related to an electrochemical reaction of the object to be measured based on a response signal.
Changing the amplitude of the perturbation signal;
Obtaining a response signal corresponding to the amplitude of the perturbation signal that changes by the step of changing the amplitude;
Based on the response signal acquired by the step of acquiring the response signal, acquiring the amplitude of the perturbation signal in which nonlinearity of the impedance of the measurement object appears;
An electrochemical reaction measuring method comprising:   2. The electrochemical method according to claim 1, further comprising a step of calculating an impedance of the object to be measured according to an amplitude of the perturbation signal based on the response signal acquired in the step of acquiring the response signal. Reaction measurement method.   The electrochemical reaction measurement method according to claim 1, further comprising a step of calculating a frequency spectrum of the response signal acquired by the step of acquiring the response signal. 4. The electrochemical reaction measurement method according to claim 3 , wherein the frequency spectrum is an amplitude spectrum or a phase spectrum of the response signal acquired in the step of acquiring the response signal. In an electrochemical reaction measuring device that gives a perturbation signal to an object to be measured and performs measurement related to an electrochemical reaction of the object to be measured based on a response signal.
Amplitude control means for changing the amplitude of the perturbation signal;
Response signal acquisition means for acquiring a response signal corresponding to the amplitude of the perturbation signal that is changed by the amplitude control means;
Based on the response signal acquired by the response signal acquisition means, amplitude acquisition means for acquiring the amplitude of the perturbation signal in which nonlinearity of the impedance of the object to be measured appears;
An electrochemical reaction measuring device comprising:

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