Battery internal characteristics data correction method and correction device

Abstract

To provide a battery degradation determination assisting device which is compact and consumes less power, and with which measurement time can be significantly shortened.SOLUTION: Provided is a method for assisting in determining degradation by acquiring the internal characteristics of an electric energy supply medium by an electrical circuit. The method includes: acquiring the internal characteristics of a battery in advance; selecting two or more frequencies required for determining whether or not the battery is good; preserving a selected frequency; performing discharge control based on the selected frequency and acquiring voltage data and current data using voltage measurement means and current measurement means; performing correction processing on the voltage data to calculate corrected voltage data; calculating resistance data from the corrected voltage data and the current data; calculating at least partial cole-cole plot data from the resistance data; and performing fitting processing using the at least partial cole-cole plot data as necessary.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for assisting in determining the deterioration of an electric energy supply medium such as a battery, and more particularly to a method for assisting in determining the deterioration of an electric energy supply medium such as a battery. Specifically, lithium-ion secondary batteries, nickel-metal hydride secondary batteries, solar cells, fuel cells, etc. The present invention relates to a method for assisting in determining battery deterioration by acquiring internal characteristics of the battery. [Background technology]

[0002] In recent years, various methods have been proposed for diagnosing the deterioration state of electric energy supply media such as secondary batteries. As one of the diagnostic methods, the horizontal axis shows the real part of the AC impedance of the secondary battery, etc. Cole-Cole plot ( Cole-Cole plot or Nyquist plot is used.

[0003] (Explanation of the Cole-Cole plot principle) The Cole-Cole plot is based on the AC-IR measurement method, which measures the internal resistance of a battery using an alternating current. Specifically, the measured values ​​are plotted by applying various frequencies to the battery under test. The current and voltage values ​​are measured when a sine wave is applied, and the resistance value including the phase difference is calculated from these values. 1 is a scatter diagram obtained by calculating the resistance and plotting the real and imaginary parts of the resistance. In AC, the voltage value V = Vr + Vi × j (where j = (-1) 0.5 ), electric The current value I is expressed as Ir + Ii × j, and the resistance value R is calculated as a complex number, V / I. For example, V=-229.585443703293-4195.93748617154i, I=-1.47516371438595- When the value is 5.46385648982277i, the result is R=0.0012072190153994-0.000304333685571092i .

[0004] Also, applying a sine wave means charging and discharging the battery being measured. The frequency set for measurement ranges from 0.1Hz to 1kHz, with several tens to hundreds of points. Measurement is required. At high frequencies, the measurement time is not an issue, but for example, when the frequency is 0.1 Hz, Since it takes 10 seconds to measure at each frequency, it takes 10 seconds to measure at all planned frequencies. It takes about a few minutes to 10 minutes. If noise leveling is performed to further reduce noise, additional measurement time is required. If you want to take the average of the number of measurements, it will take about 20 to 30 minutes, which is four times the time required for the example above. Time passes.

[0005] Referring to Figures 8A and 8B, the call-call process was calculated from the measurement results using the AC-IR measuring instrument. FIG. 8A shows an example of a measurement result using an AC-IR measuring instrument. In other words, the figure shows that various frequencies are applied to the battery being measured by an AC-IR measuring instrument. The current and voltage values ​​were measured when several sine waves were applied, and the values ​​calculated from these measurements were The resistance values ​​(real and imaginary resistance parts) including the phase difference are listed for each frequency. Figure 8B shows the real and imaginary parts of the resistance plotted against the frequency shown in Figure 8A. In addition, in the Cole-Cole plot shown in FIG. 8B, the zero crossing point The change point (depressed part B in the figure) is under the same conditions (temperature, battery voltage, etc.) If the batteries have the same characteristics, they will tend to appear in the same position. If this deviation occurs under the same conditions and with batteries of the same characteristics, it means that the battery is abnormal or deteriorated. This type of determination method is used, for example, in checks during the manufacturing of battery products. It will be possible to use it.

[0006] (AC-IR measurement method) The AC-IR measurement method estimates the internal parameter values ​​of a battery by acquiring the AC characteristics of the battery. In the conventional method, the degree to which each parameter value differs from the normal value is determined. The degree of battery deterioration was estimated by checking the deviation between the two. The method is also used, but this is a judgment based on the resistance value measured by DC current to measure the internal resistance of the battery. The AC-IR measurement method is a low current load, so it causes less damage to the battery. This allows for more reliable measurements than the DC-IR measurement method, which only reveals some of the characteristics. It is said that the AC characteristics obtained by the AC-IR measurement method can be used not only for storage batteries but also for solar cells, It can be used to understand various reaction states such as fuel cells and chemical reactions.

[0007] FIG. 9A conceptually shows the physical structure of a lithium ion secondary battery. The battery 900 includes a positive electrode 910, a negative electrode 920, and an electrolyte 930. In one embodiment, the positive electrode In 910, an aluminum alloy foil having a thickness of about 15 to 30 μm is used as a positive electrode current collector 911. The negative electrode 920 uses pure copper such as rolled copper foil or electrolytic copper foil as a negative electrode current collector 921. 940 is a material that is used to treat the decomposition of electrolyte and additives during the initial charging process of lithium-ion secondary batteries. Therefore, the Li compound formed on the negative electrode is called SEI (Solid Electrolyte Interphase) In addition, particles without a reference number in the figure represent various additives. The hexagonal particles exemplified by 951a and 951b are Li+ (ions ) is shown.

[0008] The physical structure of the secondary battery as shown in FIG. 9A corresponds to the equivalent circuit 950 shown in FIG. 9B. The circuit shown in Figure 9B can be considered as an equivalent circuit of the SEI. RC parallel circuit 961 which is the equivalent circuit of the anode (positive electrode part) and RC parallel circuit 962 which is the equivalent circuit of the anode (positive electrode part). and an RC parallel circuit 963 which is an equivalent circuit of the cathode (negative electrode part). In a parallel circuit, CPE F , CPE A , CPE C is easily affected by temperature, In the figure, capacitors are represented by special symbols. Based on the above explanation with reference to FIGS. 9A and 9B, the second-order Cole-Cole plot The battery deterioration diagnosis is successful.

[0009] Furthermore, the information that can be read from the Cole-Cole plot is as shown in Figure 9C. The fastest response frequency of the solution resistance appears in the 1k to 300Hz range, and the electric double layer resistance of the electrode surface The response frequency of the diffusion resistance of the active material inside the electrode is in the 300Hz to 0.1Hz range. Therefore, a separate equivalent circuit model (simple equivalent circuit model) is used. The simplified equivalent circuit model shown in Figure 9D is sometimes used. It is now possible to read the internal characteristic parameter values ​​of the battery, allowing the deterioration of the battery to be determined. It becomes like this. In the Cole-Cole plot shown in FIG. 8B, the zero crossing point (A in the figure) The change point (depressed part B in the figure) is under the same conditions (temperature, battery voltage, etc., the same below) and the same characteristics. I mentioned that if the battery is a sexual battery, it tends to appear in the same position. However, AC-IR is easily affected by temperature and SoC (State of Charge). It also means that it has the property of being

[0010] Based on this conventional method, it is possible to quickly measure the secondary battery while reducing the calculation load of the measuring device. A battery degradation diagnosis system that diagnoses the degradation state of a battery has been proposed (Patent Document 1).

[0011] Specifically, a measuring device for measuring battery state data relating to the state of electrical characteristics of a secondary battery. and a diagnostic processing device for diagnosing a deterioration state of the secondary battery, a storage means for storing in advance battery deterioration information for identifying deterioration characteristics of the secondary battery; a receiving means for receiving the battery status data from the measuring device; When the battery condition data is received, the battery condition data is stored in the storage means. a calculation means for calculating a deterioration state of the secondary battery corresponding to the battery state data; a diagnostic result indicating a deterioration state of the secondary battery calculated by the second stage and transmitted to the measuring device; A battery deterioration diagnosis system is disclosed, comprising: a signaling means;

[0012] In addition, a secondary battery state determination method and a secondary battery state determination method capable of determining the state of a secondary battery more accurately are provided. Next, a battery state determination device has been proposed (Patent Document 2, Patent Document 3).

[0013] That is, in Patent Document 2, an AC voltage or an AC current is applied to a secondary battery to be judged. The complex impedance measured by A method for determining a state of a secondary battery based on complex impedance, a value of the capacitance at a predetermined frequency and a first judgment value used to judge the negative electrode capacity deviation. a first capacitance deviation determination step of determining whether or not there is a first capacitance deviation based on a comparison of the first capacitance deviation and the second capacitance deviation; When it is determined that the first capacitance deviation does not occur in the capacitance deviation determination step, The slope of the impedance in the diffusion resistance region relative to the real axis is used to determine the deviation in the positive electrode capacity. a second capacitance deviation judgment method for judging whether or not there is a second capacitance deviation based on a comparison with a second judgment value obtained by comparing the first judgment value with the second judgment value obtained by comparing the first judgment value with the second judgment value obtained by comparing the first judgment value with the second judgment value obtained by comparing the second ... A secondary battery state determination method is disclosed, which includes a determining step.

[0014] In addition, Patent Document 3 discloses a micro-short circuit in a secondary battery, which is a state where there is a high possibility of a micro-short circuit occurring. A method for determining a state of a secondary battery that determines whether it is in a short-circuit state, By applying a current to the electrode system of the secondary battery, the electron transfer resistance Rs of the secondary battery is The step of measuring the electron transfer resistance to be measured and the voltage obtained in the step of measuring the electron transfer resistance The electrode distance is compared with the predetermined lower threshold Rs min. In the step of determining whether the electrode distance is good or bad, the electron transfer resistance Rs is lower than the lower limit threshold Rs min If the measured value is equal to or greater than the above, the electrode distance is determined to be good and the secondary battery is determined to be a good product. A method for determining the state of a secondary battery is disclosed, which is characterized by comprising the steps of: [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Japanese Patent Publication No. 2020-205253 [Patent Document 2] Japanese Patent Application Publication No. 2019-049479 [Patent Document 3] Japanese Patent Publication No. 2021-174729 Summary of the Invention [Problem to be solved by the invention]

[0016] However, the conventional AR-IR measurement method is expensive, consumes a large amount of power, and requires a long measurement time. Therefore, we have no choice but to measure the battery characteristics based on the DC-IR measurement method and simple charge / discharge. For example, regarding high power consumption, The conventional AC-IR measurement method is performed by applying a sine wave to the secondary battery. Not only discharging but also charging was required. To charge the battery, a certain amount of power was required. Not only is this necessary, but if you try to increase the charge / discharge current to improve accuracy, it will require even more power. This required an AC power supply, which resulted in the equipment becoming larger. At the same time, this has raised the issue of increased manufacturing costs.

[0017] Regarding the lengthening of the measurement time, in order to measure all frequencies, the measurement time in the low frequency band is The accumulation of time was a particular challenge. [Means for solving the problem]

[0018] Therefore, the method for supporting the determination of deterioration of an electric energy supply medium according to one embodiment of the present invention is The internal characteristics of the electric energy supply medium are obtained by an electronic circuit. 1. A method for assisting in determining deterioration of an energy supply medium, the method comprising: a control means for controlling the ON / OFF of the discharge of the supply medium; a voltage measuring means for measuring the voltage of the energy supply medium and acquiring voltage measurement data; and a current measuring means for measuring the amount of current discharged from the electric energy supply medium, The circuit controls the ON / OFF control at the start and end of the measurement. and dividing the voltage difference by the discharge period in the cycle. The correction process is performed using the correction data, and the result of the correction process is calculated from the time domain. Transformation to the frequency domain (Fourier transform processing) or transformation from the time domain to the complex domain A first transformation process (Laplace transformation process) is performed on the correction data. Transformation from the domain to the frequency domain (Fourier transform processing) or from the time domain to the complex domain A second transformation process is performed to transform the first image (Laplace transformation process) to The result of the second correction process is applied to the result, and the influence of the correction process is corrected. The present invention is characterized in that it includes a process for returning the document.

[0019] The first transformation process is a Fourier transformation process, and the second transformation process is a correction A window function is applied to the correction data generated by the processing, and a Fourier transform is performed. The first corrected conversion data is converted into a second corrected conversion data by taking into account a gain coefficient due to the influence of a window function. and generating correction conversion data of

[0020] In addition, the discharge ON / OFF control frequency is selected from a plurality of frequencies, and a relatively high The correction is not performed when controlling the frequency.

[0021] The relatively high frequency is at least 1 Hz or several Hz or more. It is characterized by: [Effects of the Invention]

[0022] The battery deterioration determination support device according to one embodiment of the present invention is small and has low power consumption. This provides advantageous effects such as providing a battery deterioration determination support device that can significantly reduce measurement time. do. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an explanatory diagram illustrating an example of the overall configuration of a system including a battery deterioration determination support device according to an embodiment of the present invention; [Figure 2A] 1 is an explanatory diagram illustrating an example of measurement of a current value in a battery deterioration determination support device according to an embodiment of the present invention. [Figure 2B] 1 is an explanatory diagram illustrating an example of measuring a voltage value in a battery deterioration determination support device according to an embodiment of the present invention; [Figure 3A] 1 is a flowchart illustrating a measurement procedure in a battery deterioration determination support device according to an embodiment of the present invention. [Figure 3B] 1 is a flowchart illustrating a measurement procedure in a battery deterioration determination support device according to an embodiment of the present invention. [Figure 4A] 1 is an explanatory diagram illustrating an event that should be addressed by a battery deterioration determination support device according to an embodiment of the present invention; [Figure 4B] FIG. 10 is an explanatory diagram illustrating an example of a voltage graph used for dealing with a battery deterioration determination support device according to an embodiment of the present invention. [Figure 5A] 1 is an explanatory diagram illustrating the state before and after processing by a battery deterioration determination support device according to one embodiment of the present invention; [Figure 5B] 1 is an explanatory diagram illustrating the state before and after processing by a battery deterioration determination support device according to one embodiment of the present invention; [Figure 6] 1 is an explanatory diagram illustrating an example of a Cole-Cole plot based on the measurement results obtained by a battery deterioration determination support device according to an embodiment of the present invention. FIG. [Figure 7] FIG. 1 is an explanatory diagram illustrating a comparison between an example Cole-Cole plot based on measurements using a battery deterioration determination support device according to one embodiment of the present invention and an example Cole-Cole plot based on measurements using a conventional AC-IR measuring instrument. [Figure 8A] FIG. 10 is an explanatory diagram illustrating an example of a measurement result obtained by an AC-IR measuring instrument. [Figure 8B] FIG. 10 is an explanatory diagram illustrating an example of generating a Cole-Cole plot from measurement results obtained by an AC-IR measuring instrument. [Figure 9A] FIG. 1 is an explanatory diagram conceptually illustrating the physical structure of a conventional secondary battery. [Figure 9B] FIG. 1 is an explanatory diagram illustrating an example of an equivalent circuit based on the physical structure of a conventional secondary battery. [Figure 9C] FIG. 1 is an explanatory diagram illustrating the properties of an example Cole-Cole plot generated by measuring a conventional secondary battery with an AC-IR measuring instrument. [Figure 9D] FIG. 1 is an explanatory diagram illustrating an example of a simplified equivalent circuit based on the physical structure of a conventional secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, a battery deterioration determination support device according to an embodiment of the present invention will be described without reference to the drawings. For ease of understanding of the present invention, the term "battery" will be used. However, the present invention includes "batteries" and is widely applicable to electric energy supply media that supply electricity or power. Can be used.

[0025] FIG. 1 shows the overall configuration of a system including a battery deterioration determination support device according to one embodiment of the present invention. Here is an example.

[0026] As shown in FIG. 1, a battery deterioration determination support device 100 according to an embodiment of the present invention is included. The system includes a control signal for controlling the ON / OFF of a switch circuit, etc. Signal control I / F (111), current measurement I / F (112), and voltage measurement I / F (113) and a control unit 110 having a calculation processing unit 114 such as a CPU. A switch circuit 120, a shunt resistor 130, a resistor (discharge resistor) 140, and a shunt resistor The resistance value of the shunt resistor 130 (or the current value flowing through the shunt resistor 130) is converted into a digital signal. an A / D converter 150 for converting the voltage value of the storage battery 190 into a digital value; and a converter 160.

[0027] In one embodiment of the present invention, all elements, circuits, and devices except for the storage battery 190 in FIG. The device may be a battery deterioration determination support device or system according to the present invention. The control unit 110 may be a battery deterioration determination support device according to one embodiment of the present invention.

[0028] (Operational procedure of the battery deterioration determination support device) The operational features of the battery deterioration determination support device according to one embodiment of the present invention are not limited to these. The following are examples of such measures: (1) The response characteristics are obtained using square waves. A square wave contains the fundamental frequency and its higher frequency characteristics. For example, a 100Hz square wave By applying and taking the characteristics, it is possible to simultaneously obtain the characteristics of 300Hz, 500Hz and higher-order odd terms. Higher order terms can be obtained by Fourier transform processing to shorten the measurement time. This reduction in measurement time is achieved by reducing the amount of calculation required for the Fourier transform processing of higher-order terms. It rotates. (2) The reaction only captures the discharge characteristics. In the conventional AC-IR measurement method, both the charge and discharge characteristics were obtained. In the battery deterioration determination support device according to one embodiment, only the discharge characteristics are acquired. This feature can reduce the power consumption and the complexity associated with the increased size of the device.

[0029] As a result of being provided with these features, the battery deterioration determination support device according to one embodiment of the present invention is able to: It provides advantages such as: (A) Small size At the time of filing this application, the battery deterioration determination support device according to one embodiment of the present invention is generally The device has been miniaturized to 75.0mm x 103.0mm x 50mm, and there is potential for further miniaturization. do. (B) Low power consumption At the time of filing this application, the battery deterioration determination support device according to one embodiment of the present invention was W of low power consumption has been achieved. (C) Shortening of measurement time The battery deterioration determination support device according to one embodiment of the present invention has four measurement points on the frequency band. (Although not limited to these, in one embodiment, 0.2 Hz (F1), 1.5 Hz (F2) , 12Hz (F3), 100Hz (F4). As a result, at the time of filing this application, the measurement time was approximately 1 The results are 0 seconds and communication time is about 20 seconds (in one embodiment, the communication speed is about 100Kb ps, the data format is ASCII, and the communication speed is increased to, for example, 1Mbps, and the data format is By changing to binary, communication time can be further reduced. The measurement points have also been improved so that they can be freely selected, and ultimately two measurement points (one implementation) can be selected. The forms are 0.3Hz and 10Hz. The limit for higher-order terms is thought to be around 11th to 13th order. It can also operate at frequencies where the plot becomes broad due to being buried in noise.

[0030] (Example of system configuration of battery deterioration determination support device) An example of the system configuration of a battery deterioration determination support device according to one embodiment of the present invention is as follows. There are things like that.

[0031] (1) Configuration example 1 In the case of single cell measurement, one battery deterioration determination support device can be used for one cell of a storage battery. A control device (not shown in the figure, which is implemented by existing technology) that controls multiple battery deterioration determination support devices. The battery deterioration determination support device and the control device are connected via RS-485 or the like. They are interconnected and communicate with each other. The processed data is then analyzed in a cloud (not shown). This may be done.

[0032] This configuration reduces the cost of the battery deterioration determination support device and eliminates the need for an analysis PC, etc. It has the advantage of being essential.

[0033] (2) Configuration example 2 Measurements are taken at only the two necessary points, and fitting processing is performed using the data obtained from the measurements. In addition, the data in the non-measurement area due to the limited measurement points to two points is not included in the fitting results mentioned above. The fitting process here is based on the Cole-Cole plot. It is a process that is represented by a series connection of a resistor and multiple parallel circuits (RC or RL). The simulation is performed using an equivalent circuit and a set of a predetermined number of frequencies. As for the processing, a known processing can be adopted.

[0034] This configuration was confirmed by AC-IR measurement and Cole-Cole plot calculation on the battery production line. This allows us to meet the needs of those who want to do so. However, the cost of the equipment is high and the space required to install the measuring instrument and the complexity of securing an AC power source are required. However, this configuration requires only a device cost of several tens of thousands of yen, a space the size of a cigarette, and a USB power source. We can respond.

[0035] In one embodiment of the present invention, a fitting process is performed assuming the following circuit: It is possible to carry out the theory.

[0036] circuit=R0-p(R1,C1)-p(R2,C2)-p(R3,C3)-p (R4,L4)

[0037] However, R0 etc. represent resistors, C1 etc. represent capacitors, and L4 is an inductor. 1)" indicates a parallel connection of the elements in parentheses, and "-" indicates a series connection. As an example for understanding the present invention, [0.2, 1, 4.5, 7.5, 12.5, 36.5, 61, 97.5, A set of frequencies such as [290, 879, 1465] is adopted.

[0038] FIG. 2A shows a measurement of a current value in a battery deterioration determination support device according to one embodiment of the present invention. In the figure, the horizontal axis from around zero to around 2000 is the voltage in the section where discharge is stopped. Similarly, the horizontal axis values ​​from around 2000 to around 4000 indicate the current during discharge. The waveform shown in the figure is a square wave.

[0039] To be precise, since measurements were taken at approximately 20 points during the discharge period, the sampling points were from 20 to 2068. , and then 2068 becomes 4116. That is 2048+20, 4096+20. The first 20 In one embodiment of the present invention, this value is set to about 2 to 3. It is considered desirable to have a maximum of around 20.

[0040] FIG. 2B shows a measurement of a voltage value in a battery deterioration determination support device according to an embodiment of the present invention. An example is shown in Fig. 2B. The horizontal axis of voltage in Fig. 2B corresponds to the horizontal axis of current in Fig. 2A. The values ​​from near zero to near 2000 on the horizontal axis indicate the voltage value during the period when discharge is stopped. The horizontal axis values ​​from around 2000 to around 4000 indicate the voltage values ​​during discharge. The waveforms shown indicate voltage values ​​corresponding to the states of discharge stop and discharge in progress.

[0041] 3A and 3B show measurements in a battery deterioration determination support device according to one embodiment of the present invention. The procedure is as follows: Measurement in the battery deterioration determination support device according to one embodiment of the present invention is performed in a global manner. In essence, the flow shown in FIG. 3A and the flow shown in FIG. 3B are processed in parallel. Specifically, in one embodiment, steps S304 to S308 in FIG. 3A and steps S351 to S353 in FIG. 3B are processed in parallel. do.

[0042] (Overview of measurement processing) First, we will explain the overall measurement process, including the measurement circuit and elements. In the flow, the SW (switching circuit) uses a FET (Field Effect Transistor) In one embodiment, the ON / OFF control of the FET is performed by using a semiconductor. PWM (Pulse Width Modulation) control is used to control the power used. It can be controlled so that it repeatedly turns on and off.

[0043] Although the present invention is not limited to this, in one embodiment, the SW is first turned ON. After the voltage / current is first sampled, the voltage / current sampling starts immediately before the After that, the ON / OFF control is repeated a predetermined number of times, and the final ON end For example, if the number of sampling times is four, the sampling is completed just before the end of the sampling period. When measuring the repetitive waveform of ON / OFF control, it is necessary to take 4.5 waveforms. At this time, the FETs are ON1 / OFF1 / ON2 / OFF2 / ON3 / OFF3 / ON4 / OFF4 / ON5 are processed repeatedly, and measurements are taken from the first ON (ON1) (first Measurement starts just before it turns OFF (OFF1), and just before it turns OFF from the last ON ( The data actually used for measurement will be data for 4 waves. do.

[0044] Next, the measurement data is read at a specified interval using the I2C (Inter-Integrated Circuit) standard. (In one embodiment, every 10 μs.) The read data is also If necessary, averaging processing can be performed. In one embodiment of the present invention, both the current and the voltage are In one embodiment, the PC performs sampling at 4096 points. It is also possible to perform processing such that the data is read out once a certain amount of measurement data has been accumulated. In another embodiment, the processing may be performed by the arithmetic processing unit 114 in the control unit 110. . In addition, since the voltage and current are A / D values, the process of converting these into voltage and current values ​​is will be carried out.

[0045] In addition, the voltage value gradually decreases due to discharge, so the voltage value at the start point and the end point will be different. do.

[0046] Therefore, the voltage value is processed as follows so that the values ​​at the start point and end point match. First, calculate the difference between the start and end voltages. Then, add this difference evenly over the discharge period. In the example mentioned above, it would be possible to add the voltage evenly to only the ON section of the four waveforms (corrected voltage data). This process ensures that the voltage at the start point and the voltage at the end point match. do. Then, for the voltage value, a 4096-point fast Fourier transform was performed on the above-mentioned correction voltage data. The result is the correction voltage FFT processing result. The values ​​are directly subjected to 4096-point FFT processing.

[0047] Next, a window function is applied to the voltage-added signal (equal division correction data) to align the start and end points. Then, the FFT processing is performed according to the input signal. Then, the gain correction is performed on the result of the FFT processing. Example: For example, using a Hanning window reduces the gain by half, so Then, the output is doubled to perform gain correction. Finally, the correction result is is added to the correction voltage FFT processing result, and the result obtained is the corrected voltage FFT processing result. do.

[0048] Then, the resistance value is calculated using the corrected voltage FFT processing results and current FFT processing results. do.

[0049] In another embodiment of the present invention, instead of the above-mentioned FFT processing, a general Fourier transform is used. Conversion may be adopted, or 1024 points may be used instead of 4096 points. It is also possible to employ the Laplace transform process (hereinafter the same applies to FFT process).

[0050] (Measurement processing flow) In FIG. 3A, when processing for one frequency is started in step S301, The process then proceeds to step S302, where SW control is started. Next, the process proceeds to step S303, where the wave to be measured is In one embodiment, when four waveforms are taken, the number of repetitions is set to The number is set to four.

[0051] Next, the process proceeds to step S304, where the SW is controlled to be ON. Next, the process proceeds to step S305. It is determined whether the specified time has elapsed. This time is determined by the frequency, and is 0.1 Hz. If the processing is for the frequency, the 5 seconds of the ON section will be the specified time here. If the answer is No in 05, the process waits until the specified time has elapsed in the same step. If the answer is Yes, proceed to the next step.

[0052] In step S306, the SW is controlled to be OFF. This is a time determined by the frequency, and is set at a frequency of 0.1 Hz. If the processing is for the wave number, the specified time is 5 seconds for the OFF section. If the answer is No in 7, the process will wait until the specified time has elapsed in the same step. If the answer is Yes, proceed to the next step.

[0053] In step S308, the number of repetitions of the waveform to be measured is set to the number of repetitions set in step S303. It is determined whether the number of times has been reached, and if it is No, the process returns to step S304. If so, the process proceeds to step S309, where the measurement for one frequency is completed.

[0054] On the other hand, the process performed in parallel with the process from step S304 to step S308 is In step S351 of FIG. 3B, the process starts. In step S352, the measurement In step S353, the voltage value / current value is acquired as data, and in step S354, the voltage value / current value is acquired as data. In step S354, the acquired data is saved.

[0055] The process of FIG. 3A may be automatically controlled by a microcomputer as PWM process. The PWM control unit automatically switches on and off. The microcomputer sets the repeat period, Only the start and stop instructions are given. Once the repeat period is set and PWM is started, This end determination time corresponds to S308. Also, on the measurement side, while S305 to S308 are controlling ON / OFF, S35 In this example, steps S1 to S354 are repeatedly executed 4096×N times. N is , is the average number of times.

[0056] The operating procedure described above is summarized in the table below. [Table 1]

[0057] Taking the second from the bottom (F2) in the table above as an example, the FET is turned on and off at a cycle of 1.531 Hz. (Actually, it controls ON / OFF / ON.) On the time axis, it is ON for 327.68 ms. Then it turns OFF for the next 327.68ms, and finally turns ON for 327.68ms. For example, it starts at about 7.68 ms after the end of the first ON and ends 320 ms after the last ON. During this time, measurements are taken every 10us, so 65,536 measurements are taken over 655.36ms. However, by taking the average of 16, the number becomes 4096. This number 16 corresponds to N mentioned above. That is, S351 to S354 are repeated a predetermined number of times and averaged as necessary. The operation flow is as follows: 1, the desired 4096 points (this number can also be freely selected) are obtained.

[0058] FIG. 4A illustrates an event that should be addressed by a battery deterioration determination support device according to one embodiment of the present invention. Fig. 4A shows the difference between when discharging (SW control is ON) and when discharging is stopped (SW control is OFF). This shows that the repetition of the interval (between 1 and 2) is repeated a little less than twice. The number of times is set to 1, and in the repeat section (one ON / OFF control of the SW), 4096 points are sampled.

[0059] What is noteworthy in Fig. 4A is that the discharge voltage in the second period is higher than the discharge voltage in the first period. The voltage at the start of discharge is slightly lower (part p in the figure). The voltage at the end of the section is lower than the voltage at the end of the discharge section of the first period by D. That is what it means.

[0060] The reason why the voltage drops in each cycle is because the discharge and discharge stop are repeated. This is due to a decrease in SoC. Specific symptoms are as follows: In FIG. 4A, if the SoC of the battery being measured at time t0 is x%, During the discharge stop period from time t1 to time t2, the SoC is maintained at x%. When discharge starts, the SoC gradually decreases until time t2 when discharge stops. Then, at time t2, a voltage drop (D) occurs due to a drop in SoC.

[0061] As mentioned in (Overview of measurement process), such a voltage drop (D) is calculated by dividing the voltage value at the start point by the voltage value at the end point. Since it is the difference between the voltage values ​​at the points, appropriate correction is required when performing FFT processing. The reason is that when FFT is processed over a finite period, there is a discrepancy between the values ​​at the start and end of the FFT conversion. If there is an excess frequency component, it will be generated (when the frequency characteristics of higher-order terms are calculated, Therefore, the two values ​​must match.

[0062] Generally, when there is a discrepancy between the signal values ​​at the start and end points, the following measures can be taken: A method of applying a window function and setting the start and end points to zero to match the data is also available. The function is to enlarge only the center part and multiply it by a function that makes the periphery closer to zero, This is a method to eliminate jumps by treating the deviation as "zero". The only cases where this is possible are functions that contain the signal characteristics in the center. If there are many numbers in the beginning and end parts, important information will be lost. In the case of transient response, applying a window function can be obtained near the start and end points. Since this would eliminate most of the response signal, we introduced a signal processing method that does not use a window function. You need to enter.

[0063] From the above considerations, in one embodiment of the present invention, the voltage value at the start point and the voltage value at the end point are set to be equal to each other. The following correction process is performed to correct the difference.

[0064] (correction processing) (1) Calculate the difference between the starting voltage and the ending voltage (D).

[0065] (2) The voltage difference D calculated in (1) above is added so that it is uniform throughout the discharge period. In other words, the waveform (one waveform in Figure 4) is equal to the number of repetitions (one in Figure 4) during the ON period. Correction voltage data is added to the above.

[0066] (3) For the voltage value, 4096-point FFT processing is performed on the above corrected voltage data. , the correction voltage is the FFT processing result.

[0067] (4) For current values, a 4096-point FFT was performed on the data obtained without correction. Processing is carried out and the correction results are obtained.

[0068] (5) Apply a window function to the voltage-added signal (equal division correction data) to align the start and end points. Then, FFT processing is performed.

[0069] (6) Gain correction is performed on the result of FFT processing. For example, a Hanning window is used. ndow) reduces the gain by half, so the output from the Hanning window is doubled. For example, gain correction is performed using the

[0070] (7) The correction result performed in (6) above is subtracted from the correction voltage FFT processing result, and the obtained The result is the corrected voltage FFT processing result.

[0071] (8) Calculate the resistance value using the corrected voltage FFT processing results and current FFT processing results. This resistance is a complex impedance consisting of a real resistance (R) and an imaginary resistance (X) for each frequency. This results in a high impedance.

[0072] From another point of view, the above processes (1) to (8) are divided into (battery transient response processing phase) and (post-processing phase). In this case, it can also be explained as follows:

[0073] (Battery transient response processing phase) (A1) The cell voltage immediately before turning off the FET for the first time (time t0) is V0 (FFT start In this case, the time from the start of FFT to the end of the first discharge is short, so It can be assumed that there is no change in SoC here (cell voltage in this vicinity is constant at V0). (This means that the

[0074] (A2) The time that the FET is turned off ends (a little after time t1), and the FET is turned on again. Set to N (start discharge). Then, the cell voltage starts to decrease rapidly. Then, FFT ends. If the cell voltage at time t2 is V1, and the SoC does not change due to discharge, V1 should be higher. It is not clear whether the voltage is higher or lower than V0. Here, it is assumed that V0.

[0075] (A3) Then, for the difference V1-V0, immediately after turning on the FET (time The voltage starts to drop slightly after t1) and is then proportionally subtracted until the FFT ends ( At time t2), a correction is made so that the cell voltage becomes V0. When applying FFT, The start and end values ​​can be matched.

[0076] In this way, at time t0, the voltage is V0, and we assume that this value does not change until the discharge stops. (Because the time between these two is short.) At this time, D=V0-V1. In one embodiment, this D is subtracted proportionally. In actual measurement, if the time between t0 and the end of discharge is 1 ms, the number of points is 100 ( Since it takes 10us to measure one point, 1948 points are effectively apportioned. .

[0077] (Post-processing phase) (B1) FFT processing results from immediately after turning on FET to the end of FFT FFT processing is performed on the constant voltage drop. At this time, for points where the start point and end point do not match, In this case, a window function is applied.

[0078] (B2) In one embodiment of the present invention, the applicable relations are, but are not limited to, The number is a simple voltage drop function (a function in which the voltage decreases linearly over time).

[0079] As mentioned above, the measurement and correction embodiments have been explained from various angles. Add additional explanations for further elaboration.

[0080] [Supplement 1] The significance of matching the voltages at the start and end points As mentioned above, the correction process involves matching the voltages at the start and end points. This means that the difference value during the discharge period is divided equally and "adjusted." The theory is summarized as follows (1-1) to (1-4).

[0081] (1-1) First, let the starting voltage be V0, the ending voltage be V1, and the intermediate voltage be Vx. The time points of the voltage are t0, t1, and tx. Also, the sample numbers are 0, 409, and 5. Let Cx.

[0082] (1-2) The intermediate voltage Vx rises from V0 to Vx as the discharge stops. When discharge starts at V1, the intermediate voltage Vx drops toward V1.

[0083] (1-3) Here, Vd = V0 - V1 (Since SoC decreases due to discharge, V0 > V1) In one embodiment of the present invention, 4096 points are acquired, but 20 to 30 samples were also taken from the time the discharge started until it stopped, and these data were also included in the 4096 points. Therefore, the end time is 20 to 30 samples before the second discharge stop.

[0084] (1-4) If the number of samples in the section from Vx to V1 is S (= 4095 - Cx), then at time ti The voltage is corrected as V=Vi+Vd / S*(Ci-Cx). Also, if ti=tx, correct it as Vi=Vx+Vd / S*(Cx-Cx)=Vx. If ti=t1, then Vi=V1+Vd / S*(C1(=4095)-Cx) =V1+Vd=V1+V0-V1=V0, and the voltages at the start and end points are added together.

[0085] [Supplement 2] The need for a process to return the impact of the difference As explained in Supplementary Note 1, if the voltages at the start and end points are matched, the differential influence is subtracted. This will be explained using examples in (2-1) to (2-3).

[0086] (2-1) The processing in Supplement 1 is a method of proportionally adding the difference in the second discharge period. The voltage value obtained by proportional addition is not the original voltage. This is a measure to avoid errors in higher-order terms when calculating the

[0087] (2-2) Therefore, after the final FFT processing, it is necessary to restore this correction. For the processed material, Vd is zero from t0 to tx, and then decreases linearly from tx to t1. However, even if you apply FFT to this, it is still a straight line, so you will not get the results you want. do not have.

[0088] (2-3) Therefore, a window function is applied to the voltage graph data shown in Figure 4B to perform FFT processing. Then, the gain is multiplied to calculate the effect, and this is subtracted from the voltage FFT. Return to a less affected state.

[0089] [Supplement 3] The significance of not performing correction processing at high frequencies The frequency of the characteristics to be measured varies depending on the battery or discharge body being measured, but is usually 0.1 Hz. In contrast to this, the battery deterioration measurement according to one embodiment of the present invention is performed by dividing the frequency by 100. There are four measurement points on the frequency band of the decision support device (although not limited to these). In one embodiment, four frequencies are set: 0.2 Hz (F1), 1.5 Hz (F2), 12 Hz (F3), and 100 Hz (F4). ) And, although correction processing is not performed for frequencies above 10 Hz, the technology The rationale is as follows:

[0090] In other words, if a square wave of 1 wavelength at 100Hz is input, it will only last for 0.005 seconds in real time. It is calculated as ON (to be precise, it is ON / OFF / ON → end, so it is ON for 0.01 seconds During this time, the SoC will decrease by about 10%. (See the slight voltage drop at part p in FIG. 4A.)

[0091] In fact, when measured at 100Hz, the starting voltage was 3.26431V, while the ending voltage was 3.26400 During this time, there was a voltage drop of approximately 0.00031 V, but this drop was not reflected in the FFT processing. The impact was negligible.

[0092] Furthermore, in one embodiment, the actual measurements at frequencies less than 100 Hz are as follows: That is, the starting voltage measured at 12Hz was 3.26393V, while the ending voltage was The starting voltage was 3.26393V, and the ending voltage was 3.26294V when measured at 1.5Hz. The voltage was 3.26256V, and the starting voltage was 3.26050V when measured at 0.2Hz. The voltage was 3.25943V.

[0093] Although it can be determined that the influence of either on the FFT processing is small, in one embodiment of the present invention, In this case, correction processing should not be performed for frequencies above 1 Hz or a few Hz. For example, the ON time at 1Hz is 0.5 seconds, but if it is this long, In this case, the impact of a decrease in SoC is expected to be small.

[0094] [Supplementary Note 4] The significance of calculating parameters through fitting The battery deterioration determination support device according to one embodiment of the present invention has four measurement points on the frequency band. In one embodiment, the frequency is set at four points: 0.2 Hz (F1), 1.5 Hz (F2), 12 Hz (F3), and 100 Hz (F4). Based on these measurements, higher-order terms (1st, 3rd, 5th, etc.) are calculated. On the other hand, for the slower frequencies, 0.2Hz, 0.6Hz, 1.0Hz, 1.4Hz... are displayed, Under the above conditions, no frequencies lower than 0.2Hz will be produced. The faster frequencies are based on approximately 100Hz. You can output 300Hz, 500Hz, 700Hz, but for example, you can go up to 2kHz or 3kHz. This makes the gain too small, causing fluctuations due to noise.

[0095] Therefore, the above-mentioned fitting process is performed, and the circuit used for this is: circuit=R0-p(R1,C1)-p(R2,C2)-p(R3,C3)-p (R4,L4) is.

[0096] Substitute the fitting result value into the above circuit, and numerically shift the frequency outside the measurement range. The values ​​of higher-order terms can be calculated by the above calculation. In one embodiment, only two points, 0.5 Hz and 20 Hz, are measured, and the higher-order terms are used to some extent to compensate for the difference. After filling in the data, parameter calculations are performed by fitting, and the deterioration of the battery being measured can be judged satisfactorily. A simple Cole-Cole plot can be generated.

[0097] It is thought that how fast the above-mentioned 0.2Hz can be increased depends on the characteristics of the battery. 0.2Hz means that the FET ON / OFF cycle is 0.2Hz, One cycle takes 5 seconds. It may be desirable to measure 0.1Hz to create it, but in that case it will take 10 seconds. If there is not much difference in the fitting results, it is better to process from 0.5Hz. This can significantly reduce processing time to 2 seconds, and in many cases improves overall convenience. is performed at a frequency of 0.5 Hz, then fills in the higher order terms of 1.5 Hz, 7.5 Hz, etc., and The parameters are calculated by fitting, and then the control including the low speed range (0.1Hz, etc.) is calculated. It is also possible to generate a call plot.

[0098] 5A and 5B show processing by a battery deterioration determination support device according to one embodiment of the present invention. 5A shows the state before and after the battery deterioration determination support device according to one embodiment of the present invention. FIG. 5B shows an example of the measurement of the voltage value before processing by The measurement example is subjected to correction processing by a battery deterioration determination support device according to one embodiment of the present invention. As shown in Figure 5B, the voltage values ​​shown in Figure 5A are measured. The difference D between the start and end voltages is calculated by the voltage correction process described above. You can see that the overall pressure has been raised to zero. The above-mentioned FFT processing is performed on the corrected voltage values ​​shown in FIG. 5B. In other words, if we operate on the assumption that the start and end points match and this waveform repeats, Therefore, the inconvenience of abnormal data being calculated does not occur.

[0099] (Example of a Cole-Cole plot) FIG. 6 shows the results of measurements made by a battery deterioration determination support device according to one embodiment of the present invention. An example of a Cole-Cole plot is shown in FIG. 6. In FIG. 6, plots a1 to a4 are measurement points of the first-order term. Also, as the order increases, as can be seen from the scattering of the plot in the r1 region, The plots in the r1 region tend to be scattered. The plot of the r2 region is derived by arithmetic operations as a higher order term of a4. Here, we show up to the third, fifth, seventh, and ninth orders. Higher-order terms can also be obtained. However, since it overlaps with the high frequency first-order term a3, the notation is stopped here.

[0100] FIG. 7 shows a code based on measurements by a battery deterioration determination support device according to one embodiment of the present invention. Example of a Cole-Cole plot and a Cole-Cole plot based on measurements using a conventional AC-IR measuring instrument In the figure, the plots concentrated on side A are Battery1( The results are based on measurements using conventional AC-IR measuring instruments. The alcohol plot (circle plot) and the same for Battery 1 are shown in Fig. Cole-Cole plot based on measurements using a battery deterioration determination support device, etc. (△ plots). The plots concentrated on the B side are Battery 2 (deterioration) The call was based on measurements using conventional AC-IR measuring instruments for the battery Cole plot (circle plot) and Battery 2, one embodiment of the present invention Cole-Cole plot ( △plot).

[0101] Measurement using a conventional AC-IR measuring instrument and battery deterioration determination support according to one embodiment of the present invention For both measurements using devices, the results are for good and deteriorated batteries. The respective characteristics are expressed in the same manner, and the battery deterioration determination support device according to one embodiment of the present invention The measurements by these instruments are comparable to those by conventional AC-IR measuring instruments. are.

[0102] That is, a person skilled in the art can easily understand the battery deterioration determination support device according to one embodiment of the present invention. The Cole-Cole plot based on the measurements was observed, and the battery deterioration was accurately judged in the same way as before. The decision can be made.

[0103] The battery deterioration determination support device according to one embodiment of the present invention has been described above based on a specific example. However, embodiments of the present invention may also include a method or program for implementing the system or device. In addition to the program, storage media on which the program is recorded (for example, optical disks, magneto-optical disks, CD-ROM, CD-R, CD-RW, magnetic tape, hard disk, memory card, etc. It is also possible to adopt an embodiment as follows.

[0104] The implementation form of the program is an object compiled by a compiler. application programs such as executable code, interpreted program code, etc. It is not limited to programs, but can be built into the operating system. It may be in the form of a module or the like.

[0105] Furthermore, the program does not necessarily perform all processing only on the CPU on the control board. It does not need to be mounted on a board, but can be mounted on an expansion board or expansion unit added to the board as needed. A configuration in which part or all of the processing is performed by a separate processing unit (DSP, etc.) It is also possible.

[0106] All of the features described in this specification (including the claims, abstract, and drawings) and and / or all steps of any disclosed method or process, The terms may be combined in any combination except those which are mutually exclusive.

[0107] Also, each of the features described in this specification (including the claims, abstract, and drawings) , unless expressly denied, serve the same, equivalent or similar purpose. Therefore, unless expressly denied, the disclosed features may be substituted with alternative features. Each listed feature is only an example of a generic series of identical or equivalent features.

[0108] Furthermore, the present invention is not limited to any of the specific configurations of the above-described embodiments. The present invention is based on all of the information disclosed in this specification (including the claims, abstract, and drawings). Any novel feature or combination thereof, or any novel method or process step described The present invention can be extended to any combination of these. [Explanation of symbols]

[0109] 10 Battery deterioration determination support device 110 control section 111 Signal control I / F 112 Current measurement I / F 113 Voltage measurement I / F 120 Switch circuit, switching circuit

Claims

1. The internal characteristics of the electric energy supply medium are obtained by an electronic circuit. A method for supporting deterioration determination of an energy supply medium, comprising: The electronic circuit a control means for controlling ON / OFF of discharge of the electric energy supply medium; Measure the voltage of the electric energy supply medium that is ON / OFF controlled. voltage measurement means for acquiring data; a current measuring means for measuring the amount of current discharged from the electric energy supply medium; The electronic circuit The voltage difference between the start and end of measurement for the period associated with the ON / OFF control is and calculating correction data by dividing the acquired voltage difference by the discharge period in the cycle. Correction processing is performed by the The result of the correction process is then converted from the time domain to the frequency domain (Fourier transform). transform processing) or the first transform processing from the time domain to the complex domain (Laplace transform processing) The conversion process is performed. The correction data is subjected to a conversion process from the time domain to the frequency domain (Fourier transform process). Alternatively, a second transformation process is performed to transform the time domain into the complex domain (Laplace transformation process). Conduct the analysis, By applying the result of the second correction process to the result of the first conversion process, , and performing a process to return the influence of the correction process. A method characterized by:

2. the first transformation process is a Fourier transformation process, The second conversion process applies a window function to the correction data generated by the correction process. The first correction transformation data generated by performing Fourier transform processing using the window function is The second correction conversion data is generated taking into account the gain coefficient due to the The method of claim 1.

3. Selecting and controlling a plurality of frequencies for ON / OFF control of the discharge, 10. The method according to claim 1, wherein said correction is not performed when a relatively high frequency is controlled.

2. The method according to claim 2.

4. The relatively high frequency is at least 1 Hz or several Hz or more. The method according to claim 3 .

5. The internal characteristics of the electric energy supply medium are obtained by an electronic circuit. A method for supporting deterioration determination of an energy supply medium, comprising: The internal characteristics of the battery are acquired in advance, and two or more frequencies necessary for determining whether the battery is good or bad are selected. , storing the selected frequency; Discharge control is performed based on the selected frequency, and a voltage measurement means and a current measurement means are used. to acquire voltage data and current data, performing a correction process on the voltage data to calculate corrected voltage data; calculating resistance data from the corrected voltage data and current data; calculating at least some Cole-Cole plot data from the resistance data; A fitting process is performed using at least a part of the Cole-Cole plot data. stomach, A predetermined threshold is set for each parameter value calculated as a result of the fitting process. Supports the assessment of deterioration by comparing with the value. A method characterized by:

6. A Cole-Cole process is performed based on the parameter values ​​calculated from the fitting results.

6. The method of claim 5, further comprising: continuing to generate batches.

7. Two frequencies necessary for determining whether the battery is good or bad are selected, and the low frequency value is It is recommended to select a high frequency as long as it does not affect the parameter calculation by tuning. The method according to claim 5 or 6, wherein the characteristic

8. Apparatus for carrying out the method according to any one of claims 1 to 7.

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