Measurement apparatus and method for determining electrical characteristics

Abstract

The present invention relates to a measurement device (5, 6) connected to a first terminal (11) and a second terminal (12) of an electrical device, such as a battery cell (10, C), and configured to determine at least one electrical characteristic of the electrical device (10, C). The measurement device (5, 6) includes an impedance measurement device (20, 21) configured to connect the electrical device (10, C) to a measurement circuit (30, 31) when the electrical device is connected to the first terminal (11) and the second terminal (12), and the impedance measurement device (20, 21) is configured to transmit a time-varying test current (I) via the measurement circuit (30, 31). test ) and provides a time-varying test current (I test ) is provided on the electrical equipment (10,C) while the voltage (U cell ) is measured, and the measured voltage (U cell ) and time-varying test current (I test ) and further configured to determine a phase shift and amplitude ratio between the time-varying test current (I test ) comprises a plurality of superimposed discrete frequencies, said discrete frequencies being distributed over a frequency range and separated from one another to avoid frequency overlap due to spectrum spreading between adjacent frequencies.

Description

[Technical Field]

[0001] The present invention relates to a measuring device connected to the first and second terminals of an electrical device, such as a battery cell, and configured to determine at least one electrical characteristic of the electrical device. In particular, the present invention relates to the measurement of the complex impedance of an electrical device. The present invention also relates to a method for determining at least one electrical characteristic of an electrical device.

[0002] Background of the Invention There is growing interest in using battery packs composed of multiple battery cells for various applications, such as powering electric or hybrid vehicles or as stationary power sources. Currently, lithium-ion cells are receiving particular attention.

[0003] Typically, individual cells in a battery pack may have somewhat different capacities and different levels of charge (SOC), for example, due to production variations. Most battery packs include a battery management system (BMS) or at least some form of balancing circuitry to prevent overcharging of individual cells, improve power output, and extend the battery pack's lifespan. Generally, it is advantageous for the differences in characteristics between individual cells to be as small as possible, as this makes battery management and balancing easier and improves the function of the battery pack. In addition, the charging capacity of a battery pack is usually limited by the capacity of the weakest / worst cell.

[0004] The need to reduce quality variability during the manufacturing of high-energy batteries has been addressed by Schnell and Reinhart, who proposed an improved quality control concept that involves different measures during the manufacturing process (Quality Management for Battery Production: A Quality Gate Concept, Precedia CIRP 57 (2016) 568-573). However, it is not precisely specified which measurements should be performed or which variability should be detected.

[0005] U.S. Patent Application Publication No. 2014 / 0212730 discloses a method for manufacturing battery packs. In this method, cells are classified based on the measurement of their internal resistance after pressure is applied, in particular, on the change in internal resistance, thereby selecting cells with similar characteristics and grouping them into corresponding battery packs to form battery packs of varying qualities. This is an interesting concept for forming battery packs with more uniform performance of the cells that make up the pack. However, it does not describe how the pressure test should be performed, and the concept is not very useful for cells where pressure does not have any particular or consistent effect on internal resistance, nor is it very useful when the "quality" of a battery cell has a broader meaning than or different from internal resistance after pressure is applied.

[0006] U.S. Patent Application Publication No. 2013 / 0317639 relates to the automated verification, validation, and post-processing of "battery objects" (cells, cartridges, modules, or packs). The document proposes the use of a robot (standalone or on a production line) equipped with test tools capable of performing various tests on the battery objects. These tests include measuring open-circuit voltage, load terminal voltage, terminal current, internal resistance (or impedance), polarity, insulation, continuity, short-circuit, and charge / discharge measurements. In this case, the battery objects are graded and classified based on the measurements, and all data can be reported and stored in different formats.

[0007] U.S. Patent Application Publication 2013 / 0317639 uses the term "impedance," but it is unclear whether this term is used as a general term for resistance or to refer to complex impedance, which has both amplitude and phase that may vary depending on the frequency of the applied time-varying current. In any case, U.S. Patent Application Publication 2013 / 0317639 does not provide information on how to measure the impedance of a battery object. In particular, it does not provide information on how to perform impedance measurements that can generate useful and reliable data and are also fast enough to be appropriate, for example, on a manufacturing line where there is limited time to perform the measurements.

[0008] It is well known that thorough measurement of the internal impedance of a battery cell can be useful in some cases, as it provides information about the cell's internal workings. However, such thorough measurements involve scanning sinusoidal currents across a wide frequency band, which takes a considerable amount of time to complete (if reliable results are desired), and therefore this type of method is primarily used in laboratories for research purposes. While several faster online impedance testing methods have been proposed based on signals such as pseudo-random binary sequences (PRBS), these methods are generally associated with larger measurement errors.

[0009] Therefore, there is still a need for measurement systems and methods that can quickly provide reliable information about the internal quality of battery cells or other similar electrical devices, particularly for use in battery cell (pack) manufacturing lines, and for testing battery cells already installed in certain applications or classifications of used battery cells.

[0010] Summary of the Invention The present invention relates to a measuring device connected to first and second terminals of an electrical device, such as a battery cell, and configured to determine at least one electrical characteristic of the electrical device.

[0011] This measuring device includes an impedance measuring device configured to connect an electrical device to a measuring circuit when the electrical device is connected to the first terminal and the second terminal, and the impedance measuring device measures a time-varying test current (I) via the measuring circuit. test ) provides a time-varying test current (I test While the device is being provided, the voltage on the electrical device is measured, and in the measuring circuit (30,31), the measured voltage (U cell ) and time-varying test current (I test It is further configured to determine the phase shift and amplitude ratio between ) and the time-varying test current (I test ) includes multiple superimposed discrete frequencies, which are distributed across a frequency range and are separated from each other to avoid frequency overlap due to spectral spread between adjacent frequencies.

[0012] The phase shift and amplitude ratio between voltage and current form the basis for calculating the internal impedance of a battery cell. While the final impedance calculation is useful in many applications, it is not necessary to perform this final calculation, as the "raw data"—namely, the voltage-current phase shift and amplitude ratio—already reflects the internal impedance of the cell.

[0013] Information about a cell's internal impedance is useful for reflecting the internal quality of the cell. For example, faint or minor electrode defects can be identified by comparing the determined internal impedance (or determined "raw data") to a baseline value for cells of the same type. Such information is difficult to obtain by other means, for example, by measuring only the cell's voltage or resistance. Cells exhibiting significantly deviated impedance can be sorted out from the production line or excluded from further use when selecting used cells. A particular advantage of this is that cells with minor defects, such as those that may not be immediately noticeable during the cell's first use but might, for example, increase the cell's degradation rate or become apparent during transport to the assembly site, can be identified and removed from the production line at an early stage. In the cell manufacturing plant, such cells can be removed during production, and in the battery pack assembly plant, deviant or substandard cells can be avoided from being included in the pack. Based on their impedance characteristics, cells can be classified and sorted into various classes so that, at a later stage, packs can be assembled using cells belonging to the same class, reducing variability in cells within a pack and thus improving the quality of the pack.

[0014] A time-varying test current may contain a variety of discrete frequencies, depending on the type of battery cell (or other electrical device) being analyzed and the frequency of interest. Various properties of cell chemistry and material properties respond to specific frequencies, and if a particular property is of interest, it is possible to concentrate the energy of the test current at the corresponding frequency. The term "time-varying" means that the test current oscillates at one or more frequencies. This is clearly in contrast to constant DC.

[0015] For example, the use of several frequencies or a wide frequency range to determine the internal impedance of an electrical circuit is sometimes called impedance spectroscopy and is well known in itself. Conventional impedance spectroscopy is typically used in studies to understand the function of a circuit or component or to investigate the effects of degradation, etc. Usually, a signal with a single frequency is applied each time, and if many frequencies are covered, the analysis is relatively time-consuming. The frequency range of interest in general impedance spectroscopy is typically in the range of 10 mHz to 100 kHz, but wider ranges are tested in studies, while smaller or partial ranges can also provide a lot of information about cell quality.

[0016] In this invention, the time-varying test current (I test The time-varying test current includes multiple superimposed discrete frequencies, which are distributed across a frequency range and separated from one another to avoid frequency overlap due to spread spectrum between adjacent frequencies. Thus, the time-varying test current includes multiple frequencies, possibly hundreds or thousands, that are separated from one another for superimposition and exist simultaneously. The separation has the effect that, preferably, the response from discrete frequencies selected to provide as much useful information as possible for a particular application can be analyzed without interference from spread spectrum effects from other frequencies that are too close to the frequency of interest.

[0017] Superposition has the effect of allowing all frequencies to be tested in a single test (instead of performing a series of tests at various frequencies). Therefore, the combined effect is that impedance analysis can be performed quickly while still yielding reliable results.

[0018] Therefore, compared to conventional impedance spectroscopy, it is possible to obtain results with comparable reliability within a very short measurement period.

[0019] Other shorter excitation signals, such as band-limited white noise, PRBS, and square pulses, do not involve the selection of separated discrete frequencies, but instead consist of a continuum of frequencies or at least a very large number of unseparated frequencies superimposed on a special signal. In such signals, it is more difficult to extract the amplitude and phase effects at each individual frequency, even with sophisticated and more advanced decoding methods.

[0020] At least theoretically, the time-varying test current generated in a measurement circuit does not necessarily need to be measured and can be determined from information about the signal applied to the measurement circuit. For example, if all electronic components involved in generating the test current function perfectly in theory or only vary the signal in a perfectly predictable manner, the current in the measurement circuit will be identical to the desired (and known) control signal, e.g., the time-varying test stimulus signal, or form a known function of this signal. However, since transistors, amplifiers, and other components may vary the signal at least slightly in an unknown manner, it is appropriate to fully measure the actual test current in the measurement circuit to obtain a reliable determination of the phase shift and amplitude ratio. Measuring the test current also reduces the requirements for accuracy and performance of test equipment, which allows for the use of less expensive hardware.

[0021] Voltage and current are determined / measured in a synchronized manner to allow for comparison between phase and amplitude.

[0022] In modern cell manufacturing or battery pack assembly lines with high cell throughput, there is little time to perform measurements on individual cells. To still enable impedance measurements in such manufacturing lines, this disclosure proposes using a signal that includes multiple frequencies superimposed on each other in a provided test current.

[0023] Furthermore, in exemplary embodiments, it is proposed to combine such signals with the integration of a measuring device into assembly line machinery / robots, for example, assembly line robots used to grasp, lift, and move battery cells on a manufacturing line (e.g., from a cell manufacturing line to a shipping container or from a shipping container to a battery pack in a line for assembling battery packs). In this way, impedance measurements can be performed while the cells are being lifted and moved, without interfering with the manufacturing of the cells or packs. Then, although a period of perhaps 20 seconds is available, this time window can be selected to be longer or shorter depending on the specific needs of the application. The frequency of the test current can also be adapted to a given maximum time window by excluding frequencies that are too low to give a meaningful measurement (i.e., frequencies that may have a period that is too long to give a meaningful measurement).

[0024] In this disclosure, the term "manufacturing line station" is used not only to refer to machinery / robots on a manufacturing line or assembly line, but also to refer to an impedance measurement station that can be partially integrated into a manufacturing line and can partially automate the handling and measurement of cells. In some modifications, cells can be transported manually or by some kind of gripping robot to an impedance measurement station located somewhat off the manufacturing line. Furthermore, the manufacturing line station can be configured to measure multiple cells simultaneously, for example, by having multiple measuring devices or by providing a measuring device equipped with multiple impedance measuring devices having corresponding cell terminal connections.

[0025] However, the measuring device does not necessarily need to be integrated into the manufacturing line station; it can be used as a separate measuring tool that can be operated manually in various applications.

[0026] In one embodiment, the impedance measuring device is configured to calculate the internal impedance of an electrical device based on the determined phase shift and amplitude ratio.

[0027] In this embodiment, the impedance measuring device is configured to measure the test current in the measurement circuit.

[0028] In one embodiment, the time-varying test current provided through the measurement circuit includes at least a first component in which the current passing through the measurement circuit forms a DC component concentrated with a specific current amplitude, and a second component which is a time-varying test stimulus signal that, when combined with the first component, causes time varying of the time-varying test current.

[0029] In this embodiment, the first component of the time-varying test current is drawn from the electrical device. Therefore, an external power supply is not required, as there is no need to drive the electrical device with current. This is typically applicable when the electrical device is a (charged) battery cell.

[0030] In one embodiment, the impedance measuring device includes a current stimulation circuit configured to generate a time-varying test stimulus signal.

[0031] In one embodiment, the impedance measuring device includes a transistor configured to receive a time-varying test stimulus signal and control a first component of the time-varying test current.

[0032] In one embodiment, the impedance measuring device includes a current sensing circuit configured to generate a signal representing the test current in the measuring circuit.

[0033] In one embodiment, the impedance measuring device includes a voltage sensing circuit configured to measure the voltage between a first terminal and a second terminal.

[0034] In an embodiment, the impedance measurement device includes a current stimulation circuit, a current sensing circuit, and a data acquisition device connected to a voltage sensing circuit, and the data acquisition device includes a calculation circuit configured to calculate the internal impedance of an electrical device based on a test current and a voltage.

[0035] In an embodiment, the impedance measurement device includes a feedback loop configured to measure a signal representing a test current in a measurement circuit, compare this signal with a time-varying test stimulation signal, and adjust an input voltage to a transistor to improve the match between the two signals in the measurement circuit. This feedback device compensates for the non-linear characteristics inherent in the transistor, ensuring that the test current follows the test stimulation.

[0036] In an embodiment, the time-varying test current includes at least one discrete frequency within the range of 10 mHz to 100 kHz. Preferably, the time-varying test current includes a plurality of superimposed discrete frequencies within the range of 10 mHz to 100 kHz.

[0037] When designing the time-varying test current (I test ) or the time-varying test stimulation signal, there are two limiting variables to consider, namely i) the sampling frequency f s and ii) the total time T (i.e., the total duration of the stimulation) for providing the time-varying test current (I test ). These values set the maximum achievable frequency where f s is the Nyquist frequency f s / 2, while T sets the limit of the lowest frequency f L = 1 / T (hereinafter also referred to as the fundamental frequency), thereby setting the limits of the measurable frequency range. Within these limits, the lowest frequency f l and the highest frequency f h used for the measurement can be selected together with a plurality of frequencies selected within this interval, and these are the frequencies used for the measurement to determine the impedance. Therefore, the frequency interval is f h < f s / 2 and f l > fL It is restricted by [the following].

[0038] Sampling frequency f s The sampling frequency is selected to be more than twice the highest frequency of interest, and can typically be selected within the range of 50 kHz to 1 MHz. This is a cost issue, as equipment with higher sampling frequencies is generally more expensive than equipment with lower sampling frequencies.

[0039] The measurement time T depends on the application, but can typically range from 1 to 100 seconds. However, shorter or longer times are possible depending on the time available for performing the test, the purpose of the measurement, and the frequency of interest. Typical available time on a production line may be a few seconds, perhaps 3 to 20 seconds.

[0040] Further available signal designs involve spacing f between adjacent discrete frequencies to avoid (significant) interference (i.e., frequency overlap) due to spread spectrum. d The goal is to set a minimum value for f. Therefore, the frequency is such that the difference between adjacent frequencies is f. d,min They should be separated in such a way that higher frequencies are at least f lower than the preceding lower frequency in adjacent pairs of discrete frequencies. d,min The Hz should be higher.

[0041] frequency interval f d The minimum value of f d,min is, f L This may relate to the lowest frequency assumed by =1 / T. The recommended interval is 8 * f L Larger f d It has interval f d The minimum value for is 4 * f L It can be set to 10. In most cases, 10 * f L The above f d That is sufficient. Therefore, f d,min ≥4 * fL = 4 / T, preferably f d,min ≥8 * f L = 8 / T, more preferably, f d,min ≥10 * f L = 10 / T.

[0042] When adjacent frequencies interfere significantly, the error in impedance calculated from current and voltage becomes larger. test If present in ), these frequencies can be excluded from the calculation.

[0043] Preferably, the interval between discrete test frequencies, i.e., the frequency interval range f d The signal energy across frequencies is zero or close to zero. This results in a high signal-to-noise ratio and more reliable decoding of the signal. Some signal energy between discrete frequencies may be acceptable depending on the application. The amplitude / signal energy between a discrete test frequency and an upper or lower adjacent discrete test frequency should be <10%, preferably <1%, or more preferably <0.1%, of the amplitude / signal energy of one of the two adjacent discrete frequencies.

[0044] A further signal design step, the fine-tuning step, involves balancing different frequency domains. If a particular frequency domain is more important to the specific electrical device or battery cell being analyzed, it is possible to improve the signal-to-noise ratio by allocating higher amplitude / signal energy to discrete frequencies in that domain.

[0045] The frequency and test duration T used are preferably selected and preset before measurement. The selected values ​​are determined, for example, by the characteristics and available time of the electrical device / battery cell, and should therefore be adapted to the requirements of the specific application.

[0046] For example, if it is desired that the measurement covers the range of 1 Hz to 100 kHz, f l =1Hz (=fundamental frequency) and f h = 100kHz. Next, f s A sampling frequency of 1 MHz can be selected, and a measurement time T = 3 seconds can be selected to satisfy the above given conditions (f h <f s / 2 and f l >f L , where f L =1 / T=1 / 3=0.333...Hz). f l When =1Hz and T=3 seconds, this corresponds precisely to the third harmonic of the sequence. This is because the first frequency component (fundamental frequency) is f l =3 * f L This means that, in order to avoid the effects of spread spectrum, for example, a minimum frequency interval f is 10 times the fundamental frequency. d,min (That is, a frequency interval of 10 times 1 / 3 Hz = 3.333 Hz is added between the discrete frequencies starting from the fundamental frequency) can be selected. This is f l =f1=3 * f L f2=13 * f L f3=23 * f L f4=33 * f L And so on, and in total, f h This provides 30,000 simultaneous discrete test frequencies up to 100 kHz.

[0047] By selecting the parameters above, some test frequencies will produce overtones for other lower frequencies, for example, f4=11 * This results in f1. This can negatively affect the measurement. Such interference overtones are considered to occur at frequency intervals f. d This can be avoided by using a series of prime numbers when setting it. For example, as in the example above, f1=3 as the lowest frequency (reference frequency). * f LUsing this, "3" is the first prime number. As above, using a minimum frequency interval coefficient of 10, the next prime number chosen to give a frequency that is at least 10 higher than the preceding frequency is 13, the next prime number is 23, and so on. In the example given here, the following sequence is when using prime numbers to determine the discrete frequencies, f1=3 * f L (1Hz), f2=13 * f L (13 / 3Hz), f3=23 * f L (23 / 3Hz), f4=37 * f L (37 / 3Hz), f5=47 * f L This can be obtained as (47 / 3Hz), etc. For such frequency intervals and frequency sequences, no interference spectral spread effect appears, and no overlapping or interference overtones are generated. In this example, this results in 16078(f1-f 16078 A test signal having discrete test frequencies is given. The signal energy for all other frequencies is preferably set to zero.

[0048] In the example above, if all available frequencies are used, f s / 2 * We were able to include a test frequency of 3 = 1,500,000. However, this resulted in spread spectral interference and overlapping overtones, which negatively affected impedance decoding in the next stage.

[0049] While the above type of sequence can theoretically contain only two frequencies, in practice it typically contains hundreds or thousands of frequencies.

[0050] The time-varying test current does not need to include all frequencies in the above type of sequence. For example, the signal energy can be set to zero for f2 in the above sequence so that for some reason the lowest frequencies are f1, f3, f4, etc.

[0051] As a principle, the lowest frequency f1 (fundamental frequency) in the frequency series can be anywhere within the interval between the lowest frequency f L and the highest possible frequency f s / 2, respectively. This is because there is no room for additional frequencies in this case. However, in reality, the lowest frequency f1 (fundamental frequency) in the frequency series is set to be relatively close to the lowest possible frequency f L .

[0052] Embodiments of the time-varying test current (I test ), that is, in addition to the discrete frequencies including a plurality of superimposed discrete frequencies, are distributed over a frequency range and separated from each other to avoid frequency overlap due to spectral spread between adjacent frequencies. These embodiments are - the adjacent frequencies are separated by a minimum frequency interval f d,min (f d,min ≧4 * f L =4 / T, preferably f d,min ≧8 * f L =8 / T, more preferably f d,min ≧10 * f L =10 / T, where f L =1 / T and T is the total time for supplying the time-varying test current); - the plurality of frequencies form a frequency series including the lowest frequency f1 and at least one higher frequency f2, f3... f h (dividing any one of the frequencies f2 to f h by f1 does not result in an integer); - dividing any one of the frequencies f1 to f h by the fundamental frequency f L results in a prime number; f1 is associated with the total time T for supplying the time-varying test current such that -f1 = N * 1 / T (where N > 2); - N is a prime number; - The plurality of superimposed discrete frequencies include at least 10 discrete frequencies, preferably at least 100, and more preferably at least 1000 discrete frequencies; - The total time T required to provide the time-varying test current must be 100 seconds or less; - The signal energy between a discrete frequency and an adjacent upper or lower discrete frequency is <10%, preferably <1%, or more preferably <0.1%, of the signal energy of one of the two adjacent discrete frequencies; - The signal energy between a discrete frequency and an adjacent discrete frequency above or below it is zero or close to zero. Includes.

[0053] Once the frequency and frequency interval to be used for measurement are determined, it is time for the next step in generating the test signal. An advantage is ensuring that the signal amplitude is limited in a way that allows the hardware device to generate the signal. This can be done by inverting the phase of a selected test frequency between 0° and 180° according to a random number sequence. A signal with that frequency and phase is a defined description of the signal in the frequency domain.

[0054] In this case, it is possible to transform the frequency components using the inverse discrete-time Fourier transform, and the inverse discrete-time Fourier transform is in the time domain (I tim Define the shape of the test signal in ). One method is to determine the amplitude of the current used when testing a battery cell (or another electrical device). Smaller battery cells should generally be tested with smaller currents. For example, a specific amplitude I ampl If =1A is desired, the test current is I test =I ampl * I tim / max(I tim ) is obtained from. In the formula, max(I tim ) is I tim This represents the highest value in the given region. A signal with a desired amplitude and frequency can be generated here.

[0055] In embodiments, the measuring device is integrated into a machine / robot on a manufacturing or assembly line. Preferably, the machine / robot on the manufacturing or assembly line is configured to grasp and / or lift electrical devices / battery cells.

[0056] In this embodiment, the first terminal and the second terminal form the positive and negative electrodes of a battery cell, which may be of the Li-ion type, respectively.

[0057] The present invention also relates to a method for determining at least one electrical characteristic of an electrical device, such as a battery cell, by connecting a measuring device to a first terminal and a second terminal of the electrical device.

[0058] This delicious, - The step of connecting the electrical device to the measurement circuit of the impedance measuring device located in the measuring device, - The step of providing a time-varying test current via a measurement circuit, - The step of measuring the voltage on the battery cell while a time-varying test current is provided, - In the measurement circuit, the steps include determining the phase shift and amplitude ratio between the measured voltage and the time-varying test current. Includes, Time-varying test current (I test ) includes multiple superimposed discrete frequencies, which are distributed across a frequency range and separated from one another to avoid frequency overlap due to spectral spread between adjacent frequencies. It is characterized by the following:

[0059] Embodiments of this method include: - A step of calculating the internal impedance of the electrical device based on the determined phase shift and amplitude ratio; - A step of measuring the test current in the measurement circuit; - The step of providing at least a first component in which the current passing through the measurement circuit forms a DC component concentrated with a specific current amplitude, a time-varying test stimulus signal which provides a second component that causes time variation of the time-varying test current, and by combining the first and second components, providing a time-varying test current via the measurement circuit; - A step of drawing the first component of the time-varying test current from the electrical device; - A step of generating a time-varying test stimulus signal using an electrical stimulation circuit; - A step of receiving a time-varying test stimulus signal in a transistor placed in an impedance measuring device; - A step of controlling the first component of the time-varying test current with a transistor; - A step of generating a signal representing the test current in the measurement circuit using a current sensing circuit located in the impedance measuring device, and / or - A step in which a test current is applied and the voltage response on the electrical device is measured, while the electrical device is grasped and / or lifted by a manufacturing line or assembly line machine / robot that incorporates a measuring device. It may include one or more of the following.

[0060] In embodiments of this method, the time-varying test current can have the characteristics already mentioned above.

[0061] The present invention will be described below with reference to the following figures. [Brief explanation of the drawing]

[0062] [Figure 1] This is a schematic diagram showing examples of a manufacturing line for producing battery cells and an example of a manufacturing line for assembling battery packs containing multiple battery cells. [Figure 2] For example, Figure 1 is a schematic diagram showing a first embodiment of an impedance measuring device suitable for use in a manufacturing line. [Figure 3]For example, this is a schematic diagram showing a second embodiment of an impedance measuring device suitable for use in a manufacturing line as shown in Figure 1. [Figure 4] This figure shows examples of time-varying test stimulus signals that can be used to generate time-varying test currents. The upper plot shows the frequency content of the signals, highlighting that various amounts of energy can be used in various frequency ranges, and the lower plot shows the resulting signals, including the frequency spectrum from the upper plot. [Figure 5] This figure shows examples of Nyquist plot impedance spectra for impedance measurements of the first and second battery cells. Each spectrum simultaneously shows the phase and amplitude of the complex impedance, and each dot represents the complex-valued impedance for a single frequency, with amplitude and phase depending on its position in the complex plane. [Figure 6] This figure shows the energy content of another example of a time-varying test stimulus signal that can be used to generate a time-varying test current. [Figure 7] This figure shows the signal corresponding to Figure 6. [Figure 8] This is a magnified view of a portion of Figure 6, showing the frequency range up to 10 Hz and indicating which discrete frequencies are actually used in the example signal. [Figure 9] Figure 7 is an enlarged view showing the signal at 1 millisecond. [Figure 10] For example, this is a schematic diagram showing a third embodiment of an impedance measuring device suitable for use in the manufacturing line shown in Figure 1.

[0063] Modes for carrying out the invention Figure 1 shows an exemplary embodiment in which the measuring device according to the present disclosure is incorporated into a manufacturing line robot in a manufacturing line, and the measuring device is positioned to measure battery cells.

[0064] Figure 1 shows a first production line 1 for manufacturing battery cells 10 (indicated as "C" in Figures 2 and 3) and a second production line 2 for assembling battery packs 100 containing multiple battery cells 10. In this example, each production line 1,2 includes measuring devices 5,6 connected to the first terminal 11 and second terminal 12 of the battery cells 10 in the corresponding production lines 1,2, and configured to determine the impedance of the battery cells 10 using impedance measuring devices 20,21 (see Figures 2 and 3). The measuring devices 5,6 are provided with first and second connecting members (not shown) adapted to be connected to the first cell terminal 11 and the second cell terminal 12, respectively.

[0065] As shown in Figure 1, the transport of cells 10 from the first production line 1 to the second production line 2 is shown by several vehicles / containers 3. Thus, Figure 1 shows that the two production lines 1 and 2 are located at different sites. However, cell manufacturing and battery pack assembly may be somewhat integrated at the same site, where specific transport between the two separate production lines 1 and 2 may not be required. Figure 1 is intended to show that, when applied to a production line related to battery cells, the present invention is applicable to production lines for both cell manufacturing and battery pack assembly, and these lines may or may not be located at a considerable distance from each other.

[0066] Figure 1 further illustrates that each production line 1,2 is equipped with production line stations in the form of a first production line robot 7 and a second production line robot 8 for grasping / holding, lifting, and moving battery cells, in particular for placing the battery cells 10 (one by one in this case) into the shipping container 9a of cell production line 1, and for lifting the individual battery cells 10 from the shipping container 9b and placing them into the battery packs 100 of battery pack assembly line 2. If the two production lines 1,2 are integrated, it may not be necessary to place the battery cells 10 into the shipping containers 9a,9b (although they may need to be placed into some kind of storage container), and it may be sufficient to use only one of the production line robots 7,8. Any specific production line grasping device, such as the robots 7,8 shown in Figure 1, is not essential to this embodiment, but measuring devices 5,6 are provided in appropriate embodiments where they are incorporated into the production line devices 7,8.

[0067] Figure 1 further shows that measuring devices 5,6 are positioned on or incorporated into each robot 7,8 in relation to the gripping tools of the robots 7,8 used to grip the battery cell 10. This means that the measuring devices 5,6 are positioned close to the cell 10 while the cell 10 is being gripped, lifted, and moved. This allows the measuring devices 5,6 to be connected to terminals 11,12 when the robots 7,8 grip the cell 10, and the connection to be maintained while the cell 10 is being lifted and moved until the cell 10 is released into the shipping container 9a or into the battery pack 100. In a typical manufacturing line of interest here, during the time spent lifting and moving the cell 10, perhaps about 10-20 seconds, the measuring devices 5,6 can perform measurements on the cell 10, thus allowing these measurements to be performed without delaying the manufacturing process and without any impact on the manufacturing process. By properly positioning and securing the measuring devices 5 and 6 to the corresponding robot / manufacturing line equipment 7 and 8, and ensuring that the gripping tools stably hold the cell 10 during lifting and movement, the measuring devices 5 and 6 do not move relative to the cell 10 during lifting / movement. This simplifies the securing of electrical connections between the cell terminals 11 and 12 and the measuring devices 5 and 6. The connecting members may be incorporated into the gripping tools of the robots 7 and 8.

[0068] As further described in relation to Figures 2 and 3, the impedance measuring devices 20,21 are configured to connect the battery cell 10,C to the measuring circuits 30,31 when connected to the first terminal 11 and the second terminal 12. The impedance measuring devices 20,21 are further configured to apply a time-varying test current through the measuring circuits 30,31. In the illustrated example, this draws a DC current from the cell 10,C to be measured (i.e., no external power supply is required in this example), and applies a time-varying stimulus signal I to the current drawn into the measuring circuits 30,31. in This is done by applying a current. Therefore, the time-varying test current consists of two components, with the current drawn from cell 10,C forming the first component, and the time-varying stimulus signal I in This forms the second component.

[0069] The impedance measuring devices 20 and 21 are used while a time-varying test current is applied (for this reason, the stimulus signal I in (While the voltage is also applied), the voltage U on battery cell 10,C cell and the test current I in the measurement circuits 30 and 31 test It is further configured to measure the test current I test is stimulus signal I in The vibration pattern may differ at least slightly from the (in this case, known) vibration pattern due to the nonlinearity or temperature effects of various electronic circuit components. Therefore, the test current I in the measurement circuits 30,31 may differ. test This is measured.

[0070] The impedance measuring devices 20 and 21 measure the voltage U cell and test current I test It is further configured to determine the phase shift and amplitude ratio between them. These data can be used to calculate the internal impedance of battery cell 10,C. Methods for calculating impedance are well known to those skilled in the art.

[0071] It should be noted that the descriptions of impedance measuring devices 20 and 21 are generally preferable even when measuring devices 5 and 6 are used in embodiments other than those illustrated in Figure 1.

[0072] The determined impedance (or determined phase shift and amplitude ratio) can be compared to reference data and used to identify potential defects inside cell 10,C, such as defects in the electrodes or electrolyte, or defects at the interface between the electrodes and electrolyte. Time-varying test current I test Different frequencies provide different kinds of information about a particular type of cell 10,C, and a particular frequency may be more useful than others for different types of cells. Time-varying test current I test (or rather, in this example, stimulus signal I inThe test current can be adapted to the type of cell 10,C being analyzed, meaning the test current can include one or more selected frequency ranges with clearly high amplitudes. It is also possible to include a very large number of discrete frequencies in the test current, and it is not necessary to analyze all frequencies, but rather to select the frequencies in the next step (i.e., in measuring voltage and current, and / or determining / calculating impedance).

[0073] Figure 2 shows an impedance measuring device 20 according to the first embodiment. The electrodes Po+11 and Po-12 of cell C (corresponding to cell 10 in Figure 1) are connected to the first measuring circuit 30, which includes a current control transistor T and a composite load and current measuring resistor R L+I It also has a second connection point Po- which is connected to the common ground GND. Transistor T is a MOSFET transistor here, but it may be another type of transistor, such as a bipolar transistor.

[0074] The measurement circuit 30 functions solely as a load, i.e., it can draw current from the cell C whose impedance is to be measured. This has the advantage of not requiring a power supply to charge cell C, which simplifies the measurement devices 5 and 6, making them suitable for use, for example, in cell and / or pack manufacturing lines. Transistor T and load resistor R L+I The device restricts operation, so current can only flow in the indicated direction. This passive design allows the circuit to draw energy / current only from cell C.

[0075] Load resistance R L+I It has two functions: 1) to form a load resistance that dissipates the power extracted from cell C, and 2) to form a current measuring resistance. In this case, the test current I in the measurement circuit 30 can be calculated from the voltage across the resistance using Ohm's law. test Information is provided regarding the actual test current I in the measurement circuit 30. test Signal I representingout A resistor R is generated. L+I The magnitude of the resistor can be, for example, 1.0Ω. This allows for a maximum current I from cell C for a cell voltage of 4V. max Given an current of 4A, the maximum power dissipation of the resistor is 16W. The accuracy of the resistor is given by the test current I. test Determines the accuracy of the measurement. (Test current I test The signal representing this is actually a voltage signal, but to show that the signal is a measure of current, for example, U out I out (This is shown.)

[0076] Transistor T is connected to op-amp OA1 and resistor R L+I Together, it constitutes a voltage-controlled current stimulation source. This stimulation source receives a time-varying stimulation signal I, which is provided as an output voltage by a digital-to-analog converter in the data acquisition device D. in Based on this, the time variation of the current in the measurement circuit 30 is controlled. (Time variation test stimulus signal I in Although it is actually a voltage signal, to show that this signal controls the test current, for example, U in I in (It is represented as follows.)

[0077] Voltage-controlled power supply and its control stimulus signal I in If not present, the measurement circuit 30 forms a simple DC circuit. Test stimulus signal I in This is a time-varying signal, that is, it changes with a specific frequency, and when this stimulus signal is applied to the current drawn from cell C via transistor T, it generates a time-varying or oscillation corresponding to the current in the measurement circuit 30. (The corresponding time-varying in the measurement circuit 30 is due to the stimulus signal I from the influence of electronic components.) in It is not necessary to accurately reflect the time variation of the actual test current I in the described embodiment. test (This is measured.) For this reason, the time-varying test current is applied through the measurement circuit 30. However, the test current may be applied by other means.

[0078] Time-varying test current Itest The average I, depending on the selected resistance. max It can be selected to vary according to the applied frequency around / 2A. Due to the impedance of cell C (or other electrical device being measured), at least a specific frequency or frequency range exists, and the test current I in the measurement circuit 30 test and voltage U on cell C cell There is some phase difference between them. Signal I out and voltage U cell Test current I test By measuring this, the impedance, as well as its amplitude and phase, can be calculated simultaneously.

[0079] Transistor T and op-amp OA1, connected as a voltage follower, control the voltage at the gate of transistor T, thereby controlling the resistor R. L+I This is a feedback loop that controls the current in the test current I. The feedback loop is provided to reduce the effects of nonlinearity in the transistor T and other components. test The desired test stimulus I in To follow, the test current I test This generates a transistor gate signal that achieves the desired spectrum and allows the cell behavior at a specific frequency to be tested as desired. Feedback controls the test signal to obtain the desired spectrum. Without feedback, the nonlinearity of the transistor affects the signal, resulting in the generation of a test signal different from the desired test stimulus, thus creating a risk of testing the cell at frequencies other than the desired frequency.

[0080] Thanks to the feedback loop, I in =3V causes R L+I A voltage of 3V is applied at this point, and therefore I out =3V. Here, R L+I =1Ω resistance is I test This corresponds to a current of 3A. The resistor R used in this example is for illustrative purposes only. L+IFor a resistance of R = 1Ω, a one-to-one correspondence is obtained between voltage and current. L+I For other values, see Ohm's Law I test =I out / R L+I The relationships between other currents and voltages are given accordingly.

[0081] The measurement circuit 30 has four connection points, namely U cell , I in , I out It is connected to data acquisition device D, which has GND.

[0082] GND is the common ground and forms the reference level. GND is connected to the negative electrode 12 of cell C and the load resistor R L+I Connected.

[0083] Test signal I used as a stimulus for current in the measurement circuit 30 in This is generated by a digital-to-analog converter (not shown) and sent to the current-controlled amplifier OA1.

[0084] Test current I test is the load resistance R L+I And, test current I test Signal I representing out The signal I is measured using a first analog-to-digital (AD) converter (not shown) in a data acquisition device D, which is configured to be connected to the input of the signal I. out The measured voltage is given by Ohm's Law I test =I out / R L+I Test current I using test It is used in the calculation.

[0085] 4th Connection U cell This involves measuring the cell voltage and the test current I test How does it respond to the time-varying stimulus signal I, that is, the current drawn from cell C? inThe first and second AD converters are connected to a second AD converter (not shown) that records how they respond to the current formed by applying a test current I. test Expression I out and voltage U cell The amplitude ratio and phase shift between them are synchronized so that they can be detected / measured at different frequencies.

[0086] Instead of using a first analog-to-digital converter and a second analog-to-digital converter to provide voltage and current signals, it is possible to use a single analog-to-digital converter with an additional sample-and-hold circuit that is triggered simultaneously, shifting the input, and thereby using a multiplexer to provide voltage and current signals that are measured synchronously.

[0087] Figure 3 shows a second embodiment of the impedance measuring device 21. The second embodiment operates according to the same basic principles as the first embodiment (Figure 2), in which current is drawn from cell C and controlled over time by transistor T. The main difference is the resistor R in the first embodiment (Figure 2). L+I This is two resistors, namely one load resistor R L and one current measuring shunt resistor R I It is divided into two parts. Load resistance R L The size of the shunt resistor R is determined so that it can absorb / dissipate the power extracted from cell C, and in particular so that it can be heated to dissipate the power as heat. In this second embodiment, the shunt resistor R I The shunt resistor R is selected to be small so as to dissipate only a small amount of power and generate only a slight amount of heat. This reduces the potential influence of temperature on current control and measurement. I This is because the resistance can be temperature-dependent. In this configuration, R L The temperature change that causes the change is controlled by the test current I, thanks to the feedback loop. test Signal I representing out It does not affect the accuracy.

[0088] Shunt resistor R I Because it is small, the voltage to it becomes low, and the actual test current I test Voltage signal I representing out It becomes smaller. In order to improve the accuracy of current measurement / calculation in data acquisition device D and the accuracy of current control in OA1, a second amplifier OA2 is added, along with a shunt resistor R I The original I generated by out It is implemented to amplify the signal. The gain of the second amplifier OA2 is selected by resistors R1 and R2. The amplified signal I out This is measured by the first AD converter and also supplied to the current feedback controller that controls transistor T. The data acquisition device D operates in the same manner as described in relation to the first embodiment in Figure 2. out and U cell Measure.

[0089] The resistance of the load resistor RL is preferably chosen to match the capacity and voltage of the battery cell C being measured, and to adapt to the desired amount of current to be drawn from the battery cell C. For example, if you are interested in performing a test with a high current reaching 60A, the load resistor R L It can have a resistance of 0.06Ω. However, any resistance can be used.

[0090] Shunt resistor R I The resistance should, in principle, be as small as possible (under conditions that it does not generate a signal that is too weak), and should also be calibrated and thermally stable to ensure proper measurement. For example, shunt resistor R I It can have a resistance of 0.1 mΩ. However, any other resistance can be used.

[0091] The third resistor R1 can have a resistance of 10 Ω, while the fourth resistor R2 can have a resistance of 10 kΩ. However, other values ​​can be selected for these components. To achieve the desired amplification with respect to the second operational amplifier OA2 and to provide high gain, the fourth resistor R2 can have a significantly larger resistance than the third resistor R1. For example, the third resistor R1 can have a resistance of 1 to 100 Ω, while the fourth resistor R2 can have a resistance of 1 to 100 kΩ.

[0092] To improve the accuracy of current control and measurement, it is beneficial to apply the latest technology in the selection of components (e.g., A / D, D / A, and OP). Furthermore, A / D converters can be coupled for relative measurement so that the voltage to each component is measured instead of measuring against a common ground reference. This reduces the sensitivity of the signal to noise on the common ground. Further improvement is achieved by utilizing a system with four-wire measurement, i.e., as in circuits 20 and 21 respectively, R L+I or R I Use to measure the current, out This can be achieved by using two wires to generate the current and two wires directly connected to the cell electrodes 11 and 12 to measure the cell voltage. In this case, relative measurement is also preferred, in which both wire pairs are coupled to a relative A / D input channel. Measurement circuits can be designed in other ways. For example, a current sensing resistor R I This can be replaced with another current sensor technology, such as a Hall effect-based transducer. Another means of improving accuracy is to configure the cell voltage measurement to accurately measure fluctuations around the apparent cell voltage.

[0093] To perform impedance measurements during short time intervals, for example, during the short time windows involved in attaching / grasping, lifting, transporting, positioning, and removing battery cells 10 / C as described in relation to Figure 1, time-efficient measurements are necessary. This involves controlling the current drawn from battery cells 10 / C by sending a multi-frequency signal I from the digital-to-analog converter of the data acquisition device D to the control gate of transistor T. in This is achieved by similar multi-frequency test current I test This generates a multi-frequency signal. A multi-frequency signal can be, for example, a polysinusoidal signal containing sine signals corresponding to a given set of discrete frequencies to be measured. It can also be another type of signal containing discrete frequencies to be measured.

[0094] Figure 4 shows an example of how a test stimulus signal can be designed. Figure 4 shows the signal in the frequency domain (upper) and the time domain (lower). The upper figure shows the energy content of the signal in the frequency domain. Regions with energy are indicated by black regions, and the signal energy is concentrated at low frequencies, with the lowest range of 0-5 kHz having the highest energy content, the 5-10 kHz range having lower energy, and the 10-50 kHz range having no energy and therefore zero. The spectrum of the actual signal is symmetrical around half the sampling rate (100 kHz), which explains why the low-frequency region of 0-10 kHz is mirrored over 100-90 kHz. Furthermore, the phase of individual frequencies changes randomly between 0° and 180°, which is done so that the time-domain signal has a limited and balanced amplitude.

[0095] The lower diagram in Figure 4 shows the resulting time-varying test signal, i.e., the test stimulus signal I. inThis shows that the time-domain signal is generated from the spectrum using the inverse discrete Fourier transform and therefore contains a selected frequency content. The spectral symmetry and random phase shift start at an amplitude of 0 and do not increase to excessively large amplitudes, thereby giving a time-domain signal that achieves the highest amplitude at the center. Many signals exist with the same spectral characteristics, but preferably, a test signal with a balanced and limited amplitude is selected, as shown in the lower part of Figure 4, as this makes it possible and easy to implement in the D / A converter and current controller. Such signal generation is well known to those skilled in the art.

[0096] Voltage U measured on cell 10,C cell and signal I in measurement circuits 30, 31 out Test current I via test This analysis can be performed, for example, using the Fast Fourier Transform (FFT) or any other suitable signal processing method for frequency analysis.

[0097] The measuring devices 5,6, and in particular the impedance measuring devices 20,21, are preferably designed to generate desired discrete frequencies with respect to the test current applied to the measuring circuits 30,31, whichever are considered interesting for the type of cell or other electrical device involved. (Of course, they should also be designed to measure voltages and currents at these frequencies and to analyze the measured data.)

[0098] Figure 5 shows an example of a spectrogram obtained from impedance spectroscopy. In the plot, the amplitude and phase of the frequency response are visualized as a complex-valued plot called a Nyquist plot. In this case, the x-axis corresponds to real values ​​and the y-axis corresponds to imaginary values ​​with a negative sign (this representation is chosen to match that used in the field of spectroscopy for historical reasons).

[0099] Figure 5 illustrates how impedance measurements can be used to identify cells with potential defects or variability, and also forms an example of a set of reference values ​​that can be compared to identify cells with potential defects or variability. The dots 51 in the first (top / left) series show the impedance spectrum of a new Li-ion battery cell, and the dots 52 in the second (bottom / right) series show the impedance spectrum of the same battery cell after degradation. That is, the first series 51 represents a set (series) of reference values, and the second series 52 represents a similar cell with defects. Various methods can be applied to automatically (mathematically) compare spectra and determine whether a particular cell exhibiting a specific impedance spectrum should be classified as defective.

[0100] If the internal impedance of an individual cell or other electrical device deviates from a reference value (or a set of reference values) by a certain margin, this individual cell can be sorted from production line 1,2, or sorted from some other selection process, or classified by various methods. Alternatively or supplementally, data related to the internal impedance of battery cells can be stored in a database. Such data may be, for example, the determined internal impedance at discrete frequencies, or a parameterized representation of the spectrum composed of the internal impedance at discrete frequencies. This data can then be used later, for example, to track discrepancies when dealing with a faulty battery pack in use.

[0101] Figures 6 to 9 show the time-varying test stimulus signals I that can be used to generate time-varying test currents. inHere is another example. Here, Figure 6 shows the relative signal energy content in different frequency ranges, Figure 7 shows the signal amplitude as a function of time, Figure 8 shows a magnified view of a portion of Figure 6, i.e., the frequency range up to 10 Hz, thereby showing which discrete frequencies are actually used in this range in the example signal, and Figure 9 shows a magnified view of the signal shown in Figure 7 at 1 millisecond.

[0102] In this example, the sampling frequency f s The frequency is 1 MHz, and the total measurement time is 10 seconds (i.e., time-varying test current I test This is the total time provided via the measurement circuits 30 and 31. This gives a fundamental frequency of 0.1 Hz (= f L =1 / T) and Nyquist frequency 500kHz(f s A theoretical frequency range is set between (2) and (3). However, in this case, a frequency range of 0.3 Hz to 100 kHz is selected for the stimulus signal (and therefore for the test current).

[0103] Figure 6 shows that different amplitude / signal energies were selected for different frequency subranges. The highest amplitude is used for frequencies up to 25 kHz, and the lowest amplitude is used for frequencies from 75 to 100 kHz.

[0104] Figure 7 shows the signal amplitude as a function of time during a 10-second measurement T. In this example, the signal contains 50611 discrete frequencies superimposed on each other, making it difficult to see the details of the signal. Along with Figure 9, which shows the signal at 1 millisecond in Figure 7, it can be seen that the signal is a complex continuous non-pulsed signal, does not appear to be a regular deformation of a sine curve, and has a non-trivial shape that is difficult to predict simply by looking at the signal.

[0105] Figure 8 shows nine first discrete frequencies f1 to f9 that are actually used in the frequency range up to 10 Hz. These are f1=0.3 Hz, f2=1.3 Hz, f3=2.3 Hz, f4=3.7 Hz, f5=4.7 Hz, f6=5.9 Hz, f7=7.1 Hz, f8=8.3 Hz, and f9=9.7 Hz. In total, there are 50,611 discrete frequencies across the entire range from 0.3 Hz to 100 kHz. The lowest frequency f1, at 0.3 Hz, is f1=N * The total time T (and fundamental frequency f) is such that 1 / T (where N=3) is obtained. L This is related to ). As can be seen from Figure 8, there is some spectral spread effect, and the frequency has a width of 2 at the base. * f L It has. In this example, the frequency is 10 * f L Minimum frequency interval f d,min It is separated using f1=k. To avoid interference from lower frequency overtones, f1=k * f L The frequency sequence starting with is selected such that k is a prime number separated by 10 or more units (k=3, 13, 23, 37, 47, etc.). Figure 8 shows the interval between frequencies f1, f2, etc., i.e., the frequency interval range f d We also show that the signal energy is 0 over that period.

[0106] Figure 10 shows an impedance measuring device according to a third embodiment. The basic structure and function of the circuit in Figure 10 are the same as those in Figure 3, and the components can have the same characteristics. The PNP-NPN MOSFET pair allows current to flow into electrical device C using T2 and current to be drawn from electrical device C using T1. Due to the PNP-NPN structure, these are mutually exclusive, so T1 and T2 cannot conduct simultaneously, causing a short circuit. While the circuits in Figures 2 and 3 only allow current to be drawn from the electrical device, the circuit in Figure 10 allows a test signal that also uses a symmetrical current to push current into the electrical device. This relies on the same type of feedback mechanism as OA1 to control the current to achieve high-precision current tracking. Compared to Figure 3, it differs slightly in that the NPN transistor in Figure 3 is replaced with a PNP transistor with the logic inverted, and OA1 also needs to be inverted.

[0107] The present invention is not limited to the embodiments described above and can be modified in various ways within the scope of the claims. For example, the measuring devices 5 and 6 do not necessarily need to be incorporated into an assembly robot or other manufacturing line equipment, nor do they necessarily need to be used in a manufacturing line. Furthermore, instead of drawing the test current or at least its first component from the battery cell being measured, it can be supplied from an external power source. Moreover, although the primary application is to perform measurements on battery cells, such as Li-ion cells, the measuring device can also be used for the analysis of fuel cells or other related electrical devices, for example.

Claims

1. In a measuring device (5, 6) connected to the first terminal (11) and the second terminal (12) of an electrical device (10, C), and configured to determine at least one electrical characteristic of the electrical device (10, C), The measuring device (5, 6) includes an impedance measuring device (20, 21) configured to connect the electrical device (10, C) to a measuring circuit (30, 31) when the electrical device is connected to the first terminal (11) and the second terminal (12). The impedance measuring devices (20, 21) are The time-varying test current (I) is transmitted via the measurement circuit (30, 31). ｔｅｓｔ ) provides, The aforementioned time-varying test current (I ｔｅｓｔ While the voltage (U) on the electrical device (10, C) is being provided, ｃｅｌｌ ) measure, In the measurement circuit (30, 31), the measured voltage (U ｃｅｌｌ ) and the aforementioned time-varying test current (I ｔｅｓｔ Determine the phase shift and amplitude ratio between ) It is further structured in the following way: The aforementioned time-varying test current (I ｔｅｓｔ ) includes multiple superimposed discrete frequency components, and the frequency intervals of these multiple superimposed discrete frequency components are separated from each other to avoid frequency overlap due to spectral spread between adjacent frequency components. Adjacent frequencies are separated by a minimum frequency interval f d, min, where f d, min ≥ 4 * f L = 4 / T, and f L = 1 / T, where T is the total time during which the time-varying test current (I test) is provided. A measuring device (5, 6) characterized by the above.

2. The measuring device (5, 6) according to claim 1, wherein the impedance measuring device (20, 21) is configured to calculate the internal impedance of the electrical device (10, C) based on the determined phase shift and amplitude ratio.

3. The impedance measuring device (20, 21) measures the time-varying test current (I) in the measuring circuit (30, 31). ｔｅｓｔ A measuring device (5, 6) according to claim 1 or 2, configured to measure ).

4. The time-varying test current (I ｔｅｓｔ ) provided through the measurement circuits (30, 31) includes at least a first component that forms a direct current component passing through the measurement circuits (30, 31), and a time-varying test stimulus signal (I ｉｎ ) that generates a time variation of the time-varying test current (I ｔｅｓｔ ) when combined with the first component, the measuring device (5, 6) according to any one of claims 1 to 3.

5. The aforementioned time-varying test current (I ｔｅｓｔ The measuring device (5, 6) according to claim 4, wherein the first component of ) is drawn from the electrical device (10, C).

6. The impedance measuring devices (20, 21) detect the time-varying test stimulus signal (I ｉｎ The measuring device (5, 6) according to claim 4 or 5, comprising a current stimulation circuit (OA1, T) configured to generate ).

7. The impedance measuring devices (20, 21) determine the time-varying test current (I ｔｅｓｔ In order to achieve the above time-varying test stimulus signal (I ｉｎ The measuring device (5, 6) according to claim 6, comprising a transistor (T) configured to enable ).

8. The impedance measuring device (20, 21) measures the time-varying test current (I) in the measuring circuit (30, 31). ｔｅｓｔ ) represents the signal (I ｏｕｔ A current sensing circuit (R) configured to generate ) Ｌ＋Ｉ , R Ｉ The measuring device (5, 6) according to claim 7, comprising OA2).

9. The impedance measuring device (20, 21) measures the voltage (U) between the first terminal (11) and the second terminal (12). ｃｅｌｌ The measuring device (5, 6) according to claim 8, comprising a voltage sensing circuit (D) configured to measure ).

10. The impedance measuring devices (20, 21) include the current stimulation circuit (OA1, T) and the current sensing circuit (R Ｌ＋Ｉ , R Ｉ , OA2) and a data acquisition device (D) connected to the voltage sensing circuit, The data acquisition device (D) determines the time-varying test current (I ｔｅｓｔ ) and the voltage (U ｃｅｌｌ The system includes a calculation circuit configured to calculate the internal impedance of the electrical device (10, C) based on the above, The measuring device (5, 6) according to claim 9.

11. The impedance measuring device (20, 21) measures the time-varying test current (I) in the measuring circuit (30, 31). ｔｅｓｔ The signal (I ｏｕｔ ) is measured, and the signal (I ｏｕｔ ) the time-varying test stimulus signal (I ｉｎ The operational amplifier compares the two signals (I out) in the measurement circuit (30, 31) and inputs the signal obtained from the comparison to the gate terminal of the transistor (T), and outputs the output from the source terminal of the transistor (T) as the signal (I out) and inputs it to the operational amplifier, thereby the two signals (I ｏｕｔ , I ｉｎ The measuring device (5, 6) according to claim 8, comprising a feedback loop configured to adjust the input voltage to the gate terminal of the transistor (T) so that the following conditions are met.

12. A measuring device (5, 6) connected to a first terminal (11) and a second terminal (12) of an electrical device (10, C), and configured to determine at least one electrical characteristic of the electrical device (10, C), The measuring device (5, 6) includes an impedance measuring device (20, 21) configured to connect the electrical device (10, C) to a measuring circuit (30, 31) when the electrical device is connected to the first terminal (11) and the second terminal (12). The impedance measuring devices (20, 21) are The time-varying test current (I test) is provided via the measurement circuit (30, 31). While the aforementioned time-varying test current (I test) is being provided, the voltage (U cell) on the electrical device (10, C) is measured. In the measurement circuit (30, 31), the phase shift and amplitude ratio between the measured voltage (U cell) and the time-varying test current (I test) are determined. It is further structured in the following way: The aforementioned time-varying test current (I test) includes a plurality of superimposed discrete frequency components, and the frequency intervals of these plurality of superimposed discrete frequency components are separated from one another to avoid frequency overlap due to spectral spread between adjacent frequency components. The aforementioned multiple superimposed discrete frequencies include the lowest frequency f1 and at least one higher frequency f2, f3, ... ｈ Forms a frequency sequence that includes The higher frequencies f2 to f in the aforementioned frequency series ｈ Dividing any one of these by frequency f1 does not produce an integer. Measuring devices (5, 6).

13. f1 is f1 = N ＊ The measuring device (5, 6) according to claim 12, which is associated with the total time T for providing the time-varying test current such that 1 / T (wherein N > 2)

14. The measuring device according to claim 13 (5, 6), wherein N is a prime number.

15. The measuring device according to any one of claims 1 to 14 (5, 6), wherein the plurality of superimposed discrete frequencies include at least 10 discrete frequencies.

16. The measuring device according to any one of claims 1 to 15 (5, 6), wherein the total time T for providing the time-varying test current is 100 seconds or less.

17. The measuring device according to any one of claims 1 to 16 (5, 6), wherein the signal energy between a discrete frequency and an adjacent discrete frequency above or below is less than 10% of the signal energy of one of the two adjacent discrete frequencies.

18. The measuring apparatus (5, 6) according to any one of claims 1 to 16, wherein the signal energy between a discrete frequency and an adjacent discrete frequency above or below it is zero.

19. The measuring device (5, 6) according to any one of claims 1 to 18, wherein the measuring device (5, 6) is incorporated into a machine / robot (7, 8) on a manufacturing line or assembly line.

20. The measuring device (5, 6) according to any one of claims 1 to 19, wherein the first terminal (11) and the second terminal (12) each form the positive and negative electrodes of a battery cell (10, C).

21. A method for determining at least one electrical characteristic of an electrical device (10, C) by connecting measuring devices (5, 6) to a first terminal (11) and a second terminal (12) of the electrical device (10, C), The steps include connecting the electrical device (10, C) to the measurement circuits (30, 31) of the impedance measuring devices (20, 21) located in the measuring device (5, 6), The time-varying test current (I) is transmitted via the measurement circuit (30, 31). ｔｅｓｔ The steps include providing, While the aforementioned time-varying test current is provided, the voltage (U) on the electrical device (10, C) ｃｅｌｌ The steps include measuring ) and In the measurement circuit (30, 31), the measured voltage (U ｃｅｌｌ ) and the aforementioned time-varying test current (I ｔｅｓｔ The steps of determining the phase shift and amplitude ratio between ) and Includes, The aforementioned time-varying test current (I ｔｅｓｔ ) includes multiple superimposed discrete frequency components, and the frequency intervals of these multiple superimposed discrete frequency components are separated from each other to avoid frequency overlap due to spectral spread between adjacent frequency components. The adjacent frequencies in the provided time-varying test current (I test) are separated by a minimum frequency interval f d, min, where f d, min ≥ 4 * f L = 4 / T and f L = 1 / T, where T is the total time the time-varying test current (I test) is provided. A method characterized by the following features.

22. The method described above is - A step of calculating the internal impedance of the electrical device (10, C) based on the determined phase shift and amplitude ratio. The method according to claim 21, including the method described in claim 21.

23. The method described above is The time-varying test current (I) in the measurement circuit (30, 31) ｔｅｓｔ ) Steps to measure The method according to claim 21 or 22, including the method described in claim 21 or 22.

24. The method described above is At a minimum, a first component is provided that forms the DC current component passing through the measurement circuit (30, 31), and a time-varying test stimulus signal (I ｉｎ ) and the aforementioned time-varying test current (I ｔｅｓｔ A second component is provided that causes a time variation of the first component and the second component, and the time variation test current (I) is provided via the measurement circuit (30, 31). ｔｅｓｔ ) steps to provide The method according to any one of claims 21 to 23, including

25. The method described above is The aforementioned time-varying test current (I ｔｅｓｔ Steps to extract the first component of ) from the electrical device (10, C) The method according to claim 24, including the method described in claim 24.

26. The method described above is The aforementioned time-varying test stimulus signal (I ｉｎ ) is generated by an electrical stimulation circuit (OA1, T) The method according to claim 24 or 25, including the method described in claim 24 or 25.

27. The method described above is In the transistor (T) arranged in the impedance measuring device (20, 21), the time-varying test stimulus signal (I ｉｎ The steps include receiving ) and The aforementioned time-varying test current (I ｔｅｓｔ The first component of ) is controlled by the transistor (T) The method according to any one of claims 24 to 26, including

28. The method described above is The time-varying test current (I) in the measurement circuit (30, 31) ｔｅｓｔ ) represents the signal (I ｏｕｔ ) is placed in the impedance measuring device (20, 21) and is a current sensing circuit (R Ｌ＋Ｉ , R Ｉ Steps generated by OA2) The method according to any one of claims 21 to 27, including

29. The method described above is The voltage (U) on the electrical device (10, C) ｃｅｌｌ While measuring the measurement, the machine / robot (7, 8) of the manufacturing line or assembly line incorporating the measuring devices (5, 6) grasps and / or lifts the electrical device (10, C). The method according to any one of claims 21 to 28, including

30. A method for determining at least one electrical characteristic of an electrical device (10, C) by connecting measuring devices (5, 6) to a first terminal (11) and a second terminal (12) of the electrical device (10, C), The steps include connecting the electrical device (10, C) to the measurement circuits (30, 31) of the impedance measuring devices (20, 21) located in the measuring device (5, 6), The steps include providing a time-varying test current (I test) via the measurement circuits (30, 31), The steps include measuring the voltage (U cell) on the electrical device (10, C) while the aforementioned time-varying test current is provided, In the measurement circuit (30, 31), the steps include determining the phase shift and amplitude ratio between the measured voltage (U cell) and the time-varying test current (I test), and Includes, The aforementioned time-varying test current (I test) includes a plurality of superimposed discrete frequency components, and the frequency intervals of these plurality of superimposed discrete frequency components are separated from one another to avoid frequency overlap due to spectral spread between adjacent frequency components. The aforementioned multiple superimposed discrete frequencies include the lowest frequency f1 and at least one higher frequency f2, f3, ... ｈ Forms a frequency sequence that includes The higher frequencies f2 to f in the aforementioned frequency series ｈ Dividing any one of these by frequency f1 does not produce an integer. method.

31. f1 is f1 = N ＊ The method according to claim 30, wherein the total time T for providing the time-varying test current is associated with 1 / T (wherein N > 2).

32. The method according to claim 31, wherein N is a prime number.

33. The method according to any one of claims 21 to 32, wherein the plurality of superimposed discrete frequencies include at least 10 discrete frequencies.

34. The aforementioned time-varying test current (I ｔｅｓｔ The method according to any one of claims 21 to 33, wherein the substance is provided during a period T of 100 seconds or less.

35. The method according to any one of claims 21 to 34, wherein the signal energy between a discrete frequency and an adjacent upper or lower discrete frequency is less than 10% of the signal energy of one of the two adjacent discrete frequencies.

36. The method according to any one of claims 21 to 35, wherein the signal energy between a discrete frequency and an adjacent discrete frequency above or below it is zero.

37. The measuring device according to any one of claims 1 to 11 (5, 6), wherein the minimum frequency interval f d, min is f d, min ≥ 8 * f L = 8 / T.

38. The measuring device according to any one of claims 1 to 11 (5, 6), wherein the minimum frequency interval f d, min is f d, min ≥ 10 * f L = 10 / T.

39. The method according to any one of claims 21 to 29, wherein the minimum frequency interval f d,min is f d,min ≥ 8 * f L = 8 / T.

40. The method according to any one of claims 21 to 29, wherein the minimum frequency interval f d,min is f d,min ≥ 10 * f L = 10 / T.

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