Excitation signal generation method for online test of electrochemical impedance spectroscopy of new energy battery

Abstract

The invention provides an excitation signal generation method for online test of electrochemical impedance spectroscopy of a new energy battery, and relates to the technical field of electrochemical impedance spectroscopy of the new energy battery. The method comprises the following steps: determining the amplitude of an expected Fourier coefficient according to the expected amplitude of a specified frequency of an effective frequency component set and the expected amplitude of a non-specified frequency of the effective frequency component set; repeatedly executing the following steps: determining an expected Fourier coefficient according to the amplitude of the expected Fourier coefficient and the current phase angle to obtain an actual Fourier coefficient, and replacing the current phase angle of the expected Fourier coefficient with an actual phase angle of the actual Fourier coefficient; and outputting an optimized binary sequence until iteration is performed for a preset number of times, and determining an excitation signal for online test of the electrochemical impedance spectroscopy of the new energy battery according to the optimized binary sequence. According to the invention, the interference of the online test is reduced by covering the specified frequency with the effective power as much as possible and maintaining the consistency of the normalized impedance deviation.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical impedance spectroscopy of new energy batteries, and particularly to a method for generating an excitation signal for on-line testing of electrochemical impedance spectroscopy of new energy batteries. Background Art

[0002] New energy battery technologies such as energy storage batteries, hydrogen fuel cells, and electrolytic cells are widely regarded as highly potential components in future energy solutions. These technologies not only contribute to the conversion and storage of clean energy but also play a crucial role in reducing environmental pollution and promoting sustainable development. However, the performance and lifespan of new energy batteries are significantly affected by their dynamic operating conditions and component durability. Prolonged use and environmental factors such as temperature and load changes can lead to performance degradation and even failures. Electrochemical impedance spectroscopy is a core technology for real-time diagnosis and health prediction of new energy batteries. By performing in-situ measurements to study the relationship between the AC impedance of an electrochemical system and frequency, potential performance degradation factors and failure modes can be identified.

[0003] Electrochemical impedance spectroscopy is usually obtained offline by sweep frequency technology. Although the results are relatively accurate, the measurement is time-consuming and has poor real-time performance. By integrating the electrochemical impedance spectroscopy function into power electronic devices, on-line measurement can be achieved without external equipment. At the same time, selecting an excitation signal with rich and effective harmonic components can shorten the measurement time. However, the low impedance characteristics of new energy batteries and the low signal-to-noise ratio caused by electromagnetic interference in on-line measurement seriously affect the measurement accuracy of impedance, and the limited power of the excitation signal further exacerbates the interference of noise on the electrochemical impedance spectroscopy.

[0004] Currently, there is no technical solution that can solve the above technical problems, and there is no method for generating an excitation signal for on-line testing of electrochemical impedance spectroscopy of new energy batteries. Summary of the Invention

[0005] The present invention provides a method for generating an excitation signal for on-line testing of electrochemical impedance spectroscopy of new energy batteries. By designing and optimizing a binary sequence according to the set of effective frequency components, the power is concentrated and distributed for the effective frequency components in the binary sequence signal of finite length, so as to achieve high-precision and fast on-line testing of the electrochemical impedance spectroscopy of new energy batteries.

[0006] In a first aspect, the present invention provides a method for generating an excitation signal for on-line testing of electrochemical impedance spectroscopy of new energy batteries, including: Determining the expected amplitude of the specified frequency of the set of effective frequency components according to the voltage noise component and the prior impedance, and determining the amplitude of the expected Fourier coefficient according to the expected amplitude of the specified frequency of the set of effective frequency components and the expected amplitude of the non-specified frequency of the set of effective frequency components; Repeatedly execute the following steps: Determine the expected Fourier coefficients according to the amplitude of the expected Fourier coefficients and the current phase angle, perform inverse discrete Fourier transform on the expected Fourier coefficients to obtain a time-domain signal, binarize the time-domain signal to obtain a binary sequence, perform inverse discrete Fourier transform on the binary sequence to obtain actual Fourier coefficients, and replace the current phase angle of the expected Fourier coefficients with the actual phase angle of the actual Fourier coefficients; Iterate until a preset number of times, output an optimized binary sequence, and determine an excitation signal for online measurement of the electrochemical impedance spectrum of a new energy battery according to the optimized binary sequence, so as to determine the electrochemical impedance spectrum according to the excitation signal for online measurement of the electrochemical impedance spectrum of the new energy battery.

[0007] According to the method for generating an excitation signal for online measurement of the electrochemical impedance spectrum of a new energy battery provided by the present invention, before determining the expected amplitude of a specified frequency in the effective frequency component set according to the voltage noise component and the prior impedance, the method further includes: According to the typical amplitude-frequency response of the new energy battery, determine the distribution and quantity of specified harmonics in the defined effective frequency component set at a preset impedance resolution; Determine the prior impedance according to the low-frequency resistance measurement value, the high-frequency resistance measurement value, and the linear relationship between the low-frequency resistance measurement value and the high-frequency resistance measurement value; Determine the voltage noise component according to the low-frequency noise, the band-limited white noise, and the spectral peak narrowband noise.

[0008] According to the method for generating an excitation signal for online measurement of the electrochemical impedance spectrum of a new energy battery provided by the present invention, the determining the expected amplitude of a specified frequency in the effective frequency component set according to the voltage noise component and the prior impedance includes:

[0009] Wherein, is the expected amplitude of the specified frequency in the effective frequency component set, is the prior impedance, is the voltage noise component, is the normalization term.

[0010] According to the method for generating an excitation signal for online measurement of the electrochemical impedance spectrum of a new energy battery provided by the present invention, after replacing the current phase angle of the expected Fourier coefficients with the actual phase angle of the actual Fourier coefficients, the method further includes: Initialize the optimal power distribution fitness to positive infinity, set the first convergence threshold, the second convergence threshold, and the first-order difference step size of the index, and repeat the following steps: Calculate the effective power ratio, and calculate the current power distribution fitness when the effective power ratio at the first-order difference step size is less than the first convergence threshold; When the current power distribution fitness is less than the previous power distribution fitness, update the optimal power distribution fitness and the current binary sequence; Until the optimal power distribution fitness is less than the second convergence threshold, randomly update the current phase angle.

[0011] According to the excitation signal generation method for on-line testing of the electrochemical impedance spectrum of a new energy battery provided by the present invention, after calculating the effective power ratio, the method further includes: When the effective power ratio at the first-order difference step size is greater than or equal to the first convergence threshold, determine the desired Fourier coefficient again according to the amplitude of the desired Fourier coefficient and the current phase angle, so as to obtain the actual Fourier coefficient according to the desired Fourier coefficient, and replace the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient.

[0012] According to the excitation signal generation method for on-line testing of the electrochemical impedance spectrum of a new energy battery provided by the present invention, after calculating the current power distribution fitness, the method further includes: When the current power distribution fitness is greater than or equal to the previous power distribution fitness, determine the desired Fourier coefficient again according to the amplitude of the desired Fourier coefficient and the current phase angle, so as to obtain the actual Fourier coefficient according to the desired Fourier coefficient, and replace the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient.

[0013] According to the excitation signal generation method for on-line testing of the electrochemical impedance spectrum of a new energy battery provided by the present invention, after updating the optimal power distribution fitness and the current binary sequence, the method further includes: When the optimal power distribution fitness is greater than or equal to the second convergence threshold, determine the desired Fourier coefficient again according to the amplitude of the desired Fourier coefficient and the current phase angle, so as to obtain the actual Fourier coefficient according to the desired Fourier coefficient, and replace the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient.

[0014] According to the excitation signal generation method for on-line testing of the electrochemical impedance spectrum of a new energy battery provided by the present invention, the output of the optimized binary sequence includes:

[0015] where is a value that gradually approaches 0 at frequency and is used to describe the difference between the frequency domain form of the optimized binary sequence and the desired amplitude of the specified frequency of the effective frequency component set, is at frequency A value that gradually approaches 0 below, used to describe the difference between the frequency-domain form of the optimized binary sequence and the expected amplitude of the non-specified frequency of the set of effective frequency components. is the actual signal component amplitude of the specified frequency of the set of effective frequency components EFCS, k is the harmonic order of the signal at a fixed frequency resolution, and e is the natural constant. is the imaginary unit. is the phase of the specified frequency of the set of effective frequency components EFCS.

[0016] In a second aspect, there is provided a device for generating an excitation signal for online testing of the electrochemical impedance spectrum of a new energy battery, including: A determination unit, which is used to determine the expected amplitude of the specified frequency of the set of effective frequency components according to the voltage noise component and the prior impedance, and determine the amplitude of the expected Fourier coefficient according to the expected amplitude of the specified frequency of the set of effective frequency components and the expected amplitude of the non-specified frequency of the set of effective frequency components; A repetition unit, which is used to repeatedly execute the following steps: Determine the expected Fourier coefficient according to the amplitude of the expected Fourier coefficient and the current phase angle, perform an inverse discrete Fourier transform on the expected Fourier coefficient to obtain a time-domain signal, binarize the time-domain signal to obtain a binary sequence, perform an inverse discrete Fourier transform on the binary sequence to obtain an actual Fourier coefficient, and replace the current phase angle of the expected Fourier coefficient with the actual phase angle of the actual Fourier coefficient until a preset number of iterations; An output unit, which is used to output an optimized binary sequence, determine an excitation signal for online testing of the electrochemical impedance spectrum of a new energy battery according to the optimized binary sequence, so as to determine the electrochemical impedance spectrum according to the excitation signal for online testing of the electrochemical impedance spectrum of the new energy battery.

[0017] In a third aspect, there is provided an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the program, it implements the method for generating an excitation signal for online testing of the electrochemical impedance spectrum of a new energy battery.

[0018] The present invention determines the harmonic composition of an optimized binary sequence by defining a set of effective frequency components. Meanwhile, an inverse generation method is provided to generate the iterative process of the optimized binary sequence. An index measuring the characteristics of the set of effective frequency components is used to screen the optimized binary sequence. While the designed signal has multiple frequency components, the interference in on-line testing is reduced by covering the effective power as much as possible at the specified frequencies and maintaining the consistency of the normalized impedance deviation. In the measurement of the electrochemical impedance spectrum of a new energy battery, the optimized binary sequence excitation signal designed by the present invention can inject harmonics of multiple frequency components in a short time while maintaining the consistency of the impedance deviation, and can be used to achieve high-precision and fast on-line testing of the electrochemical impedance spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following-described drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is one of the schematic flowcharts of the method for generating an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery provided by the present invention; Figure 2 It is another schematic flowchart of the method for generating an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery provided by the present invention; Figure 3 It is a schematic diagram of the design steps of the optimized binary sequence; Figure 4 It is a typical amplitude-frequency response diagram of a hydrogen fuel cell under linear-logarithmic-linear distribution; Figure 5 It is a diagram of the estimated result of voltage noise; Figure 6 It is a diagram of the iterative steps of the optimized binary sequence; Figure 7 It is a diagram of the screening steps of the optimized binary sequence; Figure 8 It is a time-domain and frequency-domain waveform diagram of the optimized binary sequence; Figure 9 It is a diagram of the electrochemical impedance spectrum result; Figure 10 It is a schematic structural diagram of the device for generating an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery provided by the present invention; Figure 11 It is a schematic structural diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Figure 1 FIG. 1 is one of the flow diagrams of the method for generating an excitation signal for on-line measurement of the electrochemical impedance spectrum of a new energy battery provided by the present invention. The method for generating an excitation signal for on-line measurement of the electrochemical impedance spectrum of a new energy battery includes: Step 101: Determine the expected amplitude of a specified frequency in the set of effective frequency components according to the voltage noise component and the prior impedance, and determine the amplitude of the expected Fourier coefficient according to the expected amplitude of the specified frequency in the set of effective frequency components and the expected amplitude of the non-specified frequency in the set of effective frequency components; Repeat the following steps: Step 102: Determine the expected Fourier coefficient according to the amplitude of the expected Fourier coefficient and the current phase angle, perform an inverse discrete Fourier transform on the expected Fourier coefficient to obtain a time-domain signal, binarize the time-domain signal to obtain a binary sequence, perform an inverse discrete Fourier transform on the binary sequence to obtain an actual Fourier coefficient, and replace the current phase angle of the expected Fourier coefficient with the actual phase angle of the actual Fourier coefficient; Step 103: Until the preset number of iterations is reached, output an optimized binary sequence, and determine an excitation signal for on-line measurement of the electrochemical impedance spectrum of a new energy battery according to the optimized binary sequence, so as to determine the electrochemical impedance spectrum according to the excitation signal for on-line measurement of the electrochemical impedance spectrum of the new energy battery.

[0023] In step 101, an embodiment of the present invention provides a method for designing an excitation signal for on-line measurement of the electrochemical impedance spectrum of new energy batteries such as energy storage batteries, hydrogen fuel cells, and electrolytic cells. Figure 2 FIG. 2 is another flow diagram of the method for generating an excitation signal for on-line measurement of the electrochemical impedance spectrum of a new energy battery provided by the present invention. First, according to the prior impedance and the battery voltage noise, a quantitative relationship between the frequency-domain expected amplitude of the optimized binary sequence and the measurement accuracy is established, and then the characteristics such as the distribution, quantity, and amplitude of the set of effective frequency components are designed; secondly, according to the effective power ratio and the power distribution adaptability index under the signal optimization objective, an inverse generation method is used to generate an optimized binary sequence with the characteristics of the expected set of effective frequency components, which is used as an excitation signal for on-line measurement of the electrochemical impedance spectrum of a new energy battery, and is superimposed with a given working current, and the whole is used as the input of a variable current controller, so as to perform broadband perturbation on the inverter, excite the response voltage of the corresponding frequency, and calculate the electrochemical impedance spectrum by measuring the voltage and current signals.

[0024] Specifically, before determining the expected amplitude of the specified frequency of the effective frequency component set based on the voltage noise component and the prior impedance, the method further includes: Determining the distribution and quantity of the specified harmonics of the defined effective frequency component set at a preset impedance resolution according to the typical amplitude-frequency response of the new energy battery; Determining the prior impedance according to the low-frequency resistance measurement value, the high-frequency resistance measurement value, and the linear relationship between the low-frequency resistance measurement value and the high-frequency resistance measurement value; Determining the voltage noise component according to the low-frequency noise, the band-limited white noise, and the spectral peak narrowband noise.

[0025] Optionally, determining the amplitude of the specified harmonics of the defined effective frequency component set on the premise of maintaining the consistency of the normalized impedance deviation according to the prior impedance and the noise estimation. Figure 4 is the typical amplitude-frequency response diagram of the hydrogen fuel cell under the linear-logarithmic-linear distribution. and are respectively the lower bound and the upper bound of the frequency interval , and the frequency bands , and correspond to the linear, logarithmic, and linear distributions respectively. The quantity of the specified frequencies of the effective frequency component set is determined according to the distribution premise. Under the logarithmic distribution, the impedance of the measured object changes significantly with the frequency, and several effective frequency points are selected per decade of frequency; under the linear distribution, the impedance change is small, and sparse frequency points are selected. The distribution and quantity of the designed effective frequency component set can reduce the signal complexity while coping with the significant changes in the amplitude-frequency curve. In this embodiment, 10 effective frequency points are selected for the frequency band that conforms to the logarithmic distribution, and 3 frequency points are selected for the frequency bands and that conform to the linear distribution.

[0026] The amplitude of the specified frequency of the effective frequency component set is determined by maintaining the consistency of the normalized impedance deviation. An expression of the normalized impedance deviation is established, which represents the relationship between the expected amplitude and the measurement accuracy: ; where is the specified frequency of the effective frequency component set, and are the measured impedance and the actual impedance respectively, and are the voltage and current harmonics without noise respectively, and are the voltage noise component and current noise component corresponding to the specified frequency in the set of effective frequency components. The involved voltage and current noise components and have random phases, such that the normalized impedance deviation has a maximum value and a minimum value. To avoid its uncertainty, the uniform distribution that conforms to the maximum entropy principle is used to simplify the expected value of the normalized deviation under the complex noise distribution is expressed as: ; Maintaining the consistency of the expected value of the normalized impedance deviation, that is, defining it as a constant, can determine the expected amplitude of the specified frequency in the set of effective frequency components , and determining the expected amplitude of the specified frequency in the set of effective frequency components according to the voltage noise component and the prior impedance includes: ; wherein, is the expected amplitude of the specified frequency in the set of effective frequency components, is the prior impedance, is the voltage noise component, is the normalization term.

[0027] The expected amplitude of the non-specified frequency in the set of effective frequency components is set to 0: ; wherein, is the harmonic order of the signal at a fixed frequency resolution, EFCS refers to the set of effective frequency components, is the frequency component of the actual signal at a fixed frequency resolution, which includes the specified frequency and other frequencies in the set of effective frequency components. The actual impedance is unknown before the electrochemical impedance spectroscopy measurement and is replaced by the prior impedance , and the voltage noise component is estimated based on the measured value of the actual noise.

[0028] Optionally, the prior impedance is distinguished according to the linear-log-linear distribution of the set of effective frequency components, and the prior impedances of the frequency bands are respectively replaced by the measured values of the low-frequency resistance and the high-frequency resistance , and the prior impedance of the frequency band is constructed by their linear relationship: ; The modeling of three main types of noise, including 1 / f noise at low frequencies, band-limited white noise, and spectral peak narrowband noise, is applied to the estimation of the voltage noise component . ​

[0029] The stochastic process of the 1 / f noise is expressed as: ; where is the cut-off frequency for distinguishing the dominant noise, and are used to describe a more general form of the 1 / f noise. The generalized parameters are solved by least squares based on the voltage noise in the region below the cut-off frequency, and then the noise estimation at the specified frequency of the optimized binary sequence is determined.

[0030] The time-domain form of the band-limited white noise is approximately a Gaussian distribution with zero mean. The real and imaginary parts of the harmonic components in the frequency domain follow an independent and identically distributed Gaussian distribution, and the amplitude follows an independent and identically distributed Rayleigh distribution. According to the frequency-domain window with an odd length of , in the Rayleigh distribution of the harmonic amplitude, the scale parameter is expressed according to the maximum likelihood estimation:

[0031] where is the harmonic order of the signal at a fixed frequency resolution.

[0032] Based on the scale parameter the mean estimation of the band-limited white noise is obtained: ; The spectral peak narrowband noise is located and estimated according to the outliers of the Rayleigh distribution of the band-limited white noise at the probability threshold . The spectral peak narrowband noise corrects the original mean estimation to the actual measured value. The outlier is expressed as: ; The 1 / f noise is used to estimate the noise level in the region below the cut-off frequency, and the band-limited white noise and the spectral peak narrowband noise are used to estimate the noise level in the region above the cut-off frequency.

[0033] The voltage noise estimation is performed in three cases: .

[0034] Figure 5 is the estimated result graph of the voltage noise. In this embodiment, the cut-off frequency is selected as 50 Hz and p is 0.95. The spectral peak narrowband noise is clearly distinguished from the 1 / f noise and the band-limited white noise floor noise, and the estimated results at the remaining specified harmonics are reasonable compared with the actual noise.

[0035] The present invention repeats step 102 until a preset number of iterations is reached, then executes step 103 to output an optimized binary sequence, and determines an excitation signal for online testing of the electrochemical impedance spectrum of a new energy battery based on the optimized binary sequence, so as to determine the electrochemical impedance spectrum based on the excitation signal for online testing of the electrochemical impedance spectrum of the new energy battery.

[0036] Figure 3 It is a schematic diagram of the optimized binary sequence design step. The present invention specifies the distribution, quantity, and amplitude of harmonics according to the defined set of effective frequency components, and iteratively generates an optimized binary sequence based on the inverse generation method. The generated optimized binary sequence is expressed in the time domain as the numerical values "-1" and "1" of the basic unit, and the actual amplitude is proportionally adjusted according to the trade-off between the measured linear conditions and accuracy. The effective power in the frequency domain of the sequence is concentrated and proportionally distributed among the desired harmonics. The distribution of the frequencies specified by the set of effective frequency components conforms to a linear-log-linear distribution and the frequency band is demarcated by the boundaries of decade frequency intervals. Based on the set of effective frequency components determined in step S1.1, the time-domain form of a discrete binary signal with a given length is arbitrarily initialized, and the corresponding frequency-domain expression is re-specified as the desired amplitudes of the frequencies specified by the set of effective frequency components and the non-specified frequencies and used as the desired Fourier coefficients of the amplitude, and the randomized phase angle is used as the phase angle of the Fourier coefficient L. An optimized binary sequence is generated through the inverse generation method. Before the iterative loop, the period T of the discrete signal and the number of iterations L are initialized according to the optimization index; for step S1.2, refer to Figure 6 the iterative steps shown, and an optimized binary sequence is obtained through iterative looping.

[0037] Figure 6 It is a diagram of the iterative steps of the optimized binary sequence. In step S2.1, the inverse discrete Fourier transform of the desired Fourier coefficients is performed to obtain the time-domain signal ; ; where is the harmonic order of the signal at a fixed frequency resolution, is the length of the discrete binary signal.

[0038] In step S2.2, the time-domain signal is binarized to obtain a binary sequence ; ; In step S2.3, the discrete Fourier transform of the binary sequence is performed to obtain the actual Fourier coefficients : ; where is the harmonic order of the signal at a fixed frequency resolution, and is the length of the discrete binary signal.

[0039] In step S2.4, the phase angle of the desired Fourier coefficient is replaced by the phase angle of the actual Fourier coefficient . The optimization objective of the iterative loop is to concentrate as much power as possible into the set of effective frequency components while meeting its power distribution requirements, as shown in the formula.

[0040] ; where is the harmonic order of the signal at a fixed frequency resolution, is the length of the discrete binary signal, EFCS refers to the set of effective frequency components, and constant is an arbitrary fixed constant.

[0041] The optimization objective can be transformed into a quantitative evaluation of two metrics: the effective power ratio and the power distribution fitness. The effective power ratio measures the degree of power concentration of the optimized binary sequence. For the th iteration, the effective power ratio of the binary sequence is expressed as: ; where is the power of the specified harmonic, is the total power. is the harmonic order of the signal at a fixed frequency resolution, is the length of the binary sequence, and EFCS refers to the set of effective frequency components. Through phase update adjustment, the effective power ratio gradually increases until it converges to the maximum value.

[0042] Optionally, the power distribution fitness measures the gap between the actual and desired power distributions among the effective harmonic components of the optimized binary sequence and is defined as: ; where represents the number of harmonics specified by EFCS. is the average of the ratio of . The power distribution fitness ranges from zero to positive infinity. The smaller this value, the more consistent the ratio of the amplitudes of the specified frequencies in the set of effective frequency components of the binary sequence is with the desired amplitudes. In this embodiment, the fixed frequency resolution is 0.1 Hz, and the length of the binary sequence is 1×10 6 .

[0043] Optionally, after replacing the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient, the method further includes: Initialize the optimal power allocation fitness to positive infinity, set the first convergence threshold, the second convergence threshold, and the first-order difference step size of the metric, and repeatedly execute the following steps: Calculate the effective power ratio. If the effective power ratio at the first-order difference step size is less than the first convergence threshold, calculate the current power allocation fitness. If the current power allocation fitness is less than the previous power allocation fitness, update the optimal power allocation fitness and the current binary sequence. Until the optimal power allocation fitness is less than the second convergence threshold, randomly update the current phase angle.

[0044] Optionally, after calculating the effective power ratio, the method further includes: If the effective power ratio at the first-order difference step size is greater than or equal to the first convergence threshold, determine the desired Fourier coefficient again according to the amplitude of the desired Fourier coefficient and the current phase angle, obtain the actual Fourier coefficient according to the desired Fourier coefficient, and replace the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient.

[0045] Optionally, after calculating the current power allocation fitness, the method further includes: If the current power allocation fitness is greater than or equal to the previous power allocation fitness, determine the desired Fourier coefficient again according to the amplitude of the desired Fourier coefficient and the current phase angle, obtain the actual Fourier coefficient according to the desired Fourier coefficient, and replace the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient.

[0046] Optionally, after updating the optimal power allocation fitness and the current binary sequence, the method further includes: If the optimal power allocation fitness is greater than or equal to the second convergence threshold, determine the desired Fourier coefficient again according to the amplitude of the desired Fourier coefficient and the current phase angle, obtain the actual Fourier coefficient according to the desired Fourier coefficient, and replace the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient.

[0047] In an alternative embodiment, Figure 7 is a flowchart of the screening step for optimizing the binary sequence. After each loop of steps S2.1 to S2.4, as Figure 5 shown, the screening step for optimizing the binary sequence is as follows: S3.1 Initialize the optimal power allocation fitness Set it to positive infinity and set the convergence threshold and , as well as the first-order difference step size a of the index; S3.2 Calculate the effective power ratio. If the effective power ratio under the first-order difference step size a is less than its threshold , then execute S3.3; otherwise, jump out of this step and execute S2.1 to S2.4; S3.3 Calculate the power allocation fitness. If a better power allocation fitness is calculated, then execute S3.4; otherwise, jump out of this step and execute S2.1 to S2.4; S3.4 Update the optimal power allocation fitness and the binary sequence. If the power allocation fitness under the first-order difference step size is less than its threshold , then execute S3.5; otherwise, jump out of this step and execute S2.1 to S2.4; S3.5 Randomly update the phase to avoid falling into a local optimal solution, jump out of this step and execute S2.1 to S2.4.

[0048] After the number of iterations meets the preset number of iterations L, update the harmonic phase corresponding to the optimal power allocation fitness under the optimal effective power ratio, and then calculate the optimized binary sequence.

[0049] By approaching the optimization goal and improving the index performance, the frequency domain form of the optimized binary sequence can be expressed as. The output optimized binary sequence includes: ; where is a value that gradually approaches 0 at frequency , used to describe the difference between the frequency domain form of the optimized binary sequence and the expected amplitude of the specified frequency in the set of effective frequency components, is a value that gradually approaches 0 at frequency , used to describe the difference between the frequency domain form of the optimized binary sequence and the expected amplitude of the non-specified frequency in the set of effective frequency components, is the actual signal component amplitude of the specified frequency in the set of effective frequency components EFCS, which can be adjusted proportionally according to the amplitude ratio adjustment of the binary sequence in the time domain form in step S1.3, is the harmonic order of the signal at a fixed frequency resolution, is the natural constant, is the imaginary unit, is the phase of the specified frequency in the set of effective frequency components EFCS.

[0050] Figure 8It is the time-domain and frequency-domain waveform diagrams of the optimized binary sequence. To optimize the time-domain and frequency-domain waveforms of the binary sequence, the main harmonics in the frequency domain are the specified harmonics of the effective frequency component set. Inevitably, there is a small amount of power waste, and this problem has been improved under the index of the effective power ratio. In addition, the harmonics of the optimized binary sequence have obvious differences due to the differences in noise and impedance, so as to achieve the consistency of the normalized impedance deviation at the specified frequency of the effective frequency component set. The optimized binary sequence of the embodiment is applied to the test of the electrochemical impedance spectrum of the hydrogen fuel cell. It is used as the excitation current to inject into the hydrogen fuel cell, and the FFT (Fast Fourier Transform) is performed on the sampled battery voltage and current signals to calculate the impedance at the specified harmonic frequency of the effective frequency component set. Figure 9 It is the result diagram of the electrochemical impedance spectrum, the convergence threshold and are 5×10 -5 and 1×10 -10 respectively, the number of iterations is 3000, and the first-order difference step size is 5.

[0051] The present invention determines the harmonic composition of the optimized binary sequence by defining the effective frequency component set. At the same time, an inverse generation method is provided to generate the iterative process of the optimized binary sequence. The index for measuring the characteristics of the effective frequency component set is used to screen the optimized binary sequence. While the designed signal has multiple frequency components, the interference of on-line testing is reduced by covering the effective power as much as possible at the specified frequency and maintaining the consistency of the normalized impedance deviation. In the measurement of the electrochemical impedance spectrum of new energy batteries, the optimized binary sequence excitation signal designed by the present invention can inject harmonics of multiple frequency components in a short time, while maintaining the consistency of impedance deviation, and can be used to achieve high-precision and fast on-line testing of the electrochemical impedance spectrum.

[0052] Figure 10 It is the structural schematic diagram of the excitation signal generation device for on-line testing of the electrochemical impedance spectrum of new energy batteries provided by the present invention. The excitation signal generation device for on-line testing of the electrochemical impedance spectrum of new energy batteries includes a determination unit 1. The determination unit 1 is used to determine the expected amplitude of the specified frequency of the effective frequency component set according to the voltage noise component and the prior impedance, and determine the amplitude of the expected Fourier coefficient according to the expected amplitude of the specified frequency of the effective frequency component set and the expected amplitude of the non-specified frequency of the effective frequency component set. The working principle of the determination unit 1 can refer to the foregoing step 101 and will not be elaborated here.

[0053] The excitation signal generation device for on-line testing of the electrochemical impedance spectrum of new energy batteries further includes a repetition unit 2. The repetition unit 2 is used to repeatedly execute the following steps: Determine the expected Fourier coefficients according to the amplitude of the expected Fourier coefficients and the current phase angle, perform inverse discrete Fourier transform on the expected Fourier coefficients to obtain a time-domain signal, binarize the time-domain signal to obtain a binary sequence, perform inverse discrete Fourier transform on the binary sequence to obtain actual Fourier coefficients, and replace the current phase angle of the expected Fourier coefficients with the actual phase angle of the actual Fourier coefficients until the preset number of iterations. The working principle of the repeating unit 2 can refer to the foregoing step 102 and will not be elaborated here.

[0054] The excitation signal generation device for online measurement of the electrochemical impedance spectrum of a new energy battery further includes an output unit 3. The output unit 3 is used to output an optimized binary sequence, determine an excitation signal for online measurement of the electrochemical impedance spectrum of a new energy battery according to the optimized binary sequence, and determine the electrochemical impedance spectrum according to the excitation signal for online measurement of the electrochemical impedance spectrum of a new energy battery. The working principle of the output unit 3 can refer to the foregoing step 103 and will not be elaborated here.

[0055] The present invention determines the harmonic composition of the optimized binary sequence by defining a set of effective frequency components, and at the same time provides an inverse generation method to generate the iterative process of the optimized binary sequence. An index measuring the characteristics of the set of effective frequency components is used to screen the optimized binary sequence. While the designed signal has multiple frequency components, the interference of online measurement is reduced by covering the effective power as much as possible at the specified frequency and maintaining the consistency of the normalized impedance deviation. In the measurement of the electrochemical impedance spectrum of a new energy battery, the optimized binary sequence excitation signal designed by the present invention can inject harmonics of multiple frequency components in a short time while maintaining the consistency of impedance deviation, and can be used to achieve high-precision and fast-speed online measurement of the electrochemical impedance spectrum.

[0056] Figure 11 It is a schematic structural diagram of an electronic device provided by the present invention. As Figure 11As shown, the electronic device may include: a processor 110, a communications interface 120, a memory 130, and a communication bus 140. Among them, the processor 110, the communications interface 120, and the memory 130 complete communication with each other through the communication bus 140. The processor 110 may call the logical instructions in the memory 130 to execute the method for generating an excitation signal for online testing of the electrochemical impedance spectrum of a new energy battery. The method includes: determining the expected amplitude of a specified frequency of an effective frequency component set according to a voltage noise component and a prior impedance, and determining the amplitude of an expected Fourier coefficient according to the expected amplitude of the specified frequency of the effective frequency component set and the expected amplitude of a non-specified frequency of the effective frequency component set; repeatedly executing the following steps: determining the expected Fourier coefficient according to the amplitude of the expected Fourier coefficient and the current phase angle, performing an inverse discrete Fourier transform on the expected Fourier coefficient to obtain a time-domain signal, binarizing the time-domain signal to obtain a binary sequence, performing an inverse discrete Fourier transform on the binary sequence to obtain an actual Fourier coefficient, and replacing the current phase angle of the expected Fourier coefficient with the actual phase angle of the actual Fourier coefficient; until a preset number of iterations, outputting an optimized binary sequence, determining an excitation signal for online testing of the electrochemical impedance spectrum of a new energy battery according to the optimized binary sequence, and determining the electrochemical impedance spectrum according to the excitation signal for online testing of the electrochemical impedance spectrum of the new energy battery.

[0057] In addition, the logical instructions in the above-mentioned memory 130 may be implemented in the form of software functional units and, when sold or used as an independent product, may be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, may be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: various media such as a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk, or an optical disc that can store program codes.

[0058] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute a method for generating an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery provided by the above-mentioned various methods. The method includes: determining the expected amplitude of a specified frequency of an effective frequency component set according to a voltage noise component and a prior impedance, and determining the amplitude of an expected Fourier coefficient according to the expected amplitude of the specified frequency of the effective frequency component set and the expected amplitude of a non-specified frequency of the effective frequency component set; repeating the following steps: determining the expected Fourier coefficient according to the amplitude of the expected Fourier coefficient and the current phase angle, performing an inverse discrete Fourier transform on the expected Fourier coefficient to obtain a time-domain signal, binarizing the time-domain signal to obtain a binary sequence, performing an inverse discrete Fourier transform on the binary sequence to obtain an actual Fourier coefficient, and replacing the current phase angle of the expected Fourier coefficient with the actual phase angle of the actual Fourier coefficient; until a preset number of iterations is reached, outputting an optimized binary sequence, and determining an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery according to the optimized binary sequence, so as to determine the electrochemical impedance spectrum according to the excitation signal for on-line testing of the electrochemical impedance spectrum of the new energy battery.

[0059] On another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it realizes the method for generating an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery provided by the above-mentioned various methods. The method includes: determining the expected amplitude of a specified frequency of an effective frequency component set according to a voltage noise component and a prior impedance, and determining the amplitude of an expected Fourier coefficient according to the expected amplitude of the specified frequency of the effective frequency component set and the expected amplitude of a non-specified frequency of the effective frequency component set; repeating the following steps: determining the expected Fourier coefficient according to the amplitude of the expected Fourier coefficient and the current phase angle, performing an inverse discrete Fourier transform on the expected Fourier coefficient to obtain a time-domain signal, binarizing the time-domain signal to obtain a binary sequence, performing an inverse discrete Fourier transform on the binary sequence to obtain an actual Fourier coefficient, and replacing the current phase angle of the expected Fourier coefficient with the actual phase angle of the actual Fourier coefficient; until a preset number of iterations is reached, outputting an optimized binary sequence, and determining an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery according to the optimized binary sequence, so as to determine the electrochemical impedance spectrum according to the excitation signal for on-line testing of the electrochemical impedance spectrum of the new energy battery.

[0060] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative effort.

[0061] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An excitation signal generation method for on-line testing of the electrochemical impedance spectrum of a new energy battery, characterized in that Including: Determine the expected amplitude of the specified frequency of the effective frequency component set according to the voltage noise component and the prior impedance, and determine the amplitude of the expected Fourier coefficient according to the expected amplitude of the specified frequency of the effective frequency component set and the expected amplitude of the non-specified frequency of the effective frequency component set; Repeatedly execute the following steps: Determine the expected Fourier coefficient according to the amplitude of the expected Fourier coefficient and the current phase angle, perform inverse discrete Fourier transform on the expected Fourier coefficient to obtain a time-domain signal, binarize the time-domain signal to obtain a binary sequence, perform inverse discrete Fourier transform on the binary sequence to obtain an actual Fourier coefficient, and replace the current phase angle of the expected Fourier coefficient with the actual phase angle of the actual Fourier coefficient; Until the preset number of iterations is reached, output an optimized binary sequence, and determine an excitation signal for online measurement of the electrochemical impedance spectrum of the new energy battery according to the optimized binary sequence, so as to determine the electrochemical impedance spectrum according to the excitation signal for online measurement of the electrochemical impedance spectrum of the new energy battery.

2. The method for generating an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery according to claim 1, characterized in that Before determining the expected amplitude of the specified frequency of the effective frequency component set according to the voltage noise component and the prior impedance, the method further includes: According to the typical amplitude-frequency response of the new energy battery, determine the distribution and quantity of the specified harmonics of the defined effective frequency component set at a preset impedance resolution; Determine the prior impedance according to the low-frequency resistance measurement value, the high-frequency resistance measurement value, and the linear relationship between the low-frequency resistance measurement value and the high-frequency resistance measurement value; Determine the voltage noise component according to the low-frequency noise, the band-limited white noise, and the spectral peak narrowband noise.

3. The excitation signal generation method for on-line testing of the electrochemical impedance spectrum of a new energy battery according to claim 1, characterized in that The determining the expected amplitude of the specified frequency of the effective frequency component set according to the voltage noise component and the prior impedance includes: ； wherein, specifies the desired amplitude of the frequency for the set of valid frequency components, is the prior impedance, is the voltage noise component, is the normalization term.

4. The excitation signal generation method for on-line testing of the electrochemical impedance spectrum of a new energy battery according to claim 1, wherein, After replacing the current phase angle of the expected Fourier coefficient with the actual phase angle of the actual Fourier coefficient, the method further includes: Initialize the optimal power distribution fitness to positive infinity, set the first convergence threshold, the second convergence threshold, and the first-order difference step size of the index, and repeatedly execute the following steps: Calculate the effective power ratio. When the effective power ratio at the first-order difference step size is less than the first convergence threshold, calculate the current power distribution fitness; When the current power distribution fitness is less than the previous power distribution fitness, update the optimal power distribution fitness and the current binary sequence; Until the optimal power distribution fitness is less than the second convergence threshold, randomly update the current phase angle.

5. The method for generating an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery according to claim 4, characterized in that, After calculating the effective power ratio, the method further includes: When the effective power ratio at the first-order difference step size is greater than or equal to the first convergence threshold, determine the expected Fourier coefficient again according to the amplitude of the expected Fourier coefficient and the current phase angle, obtain the actual Fourier coefficient according to the expected Fourier coefficient, and replace the current phase angle of the expected Fourier coefficient with the actual phase angle of the actual Fourier coefficient.

6. The method for generating an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery according to claim 4, wherein After calculating the current power distribution fitness, the method further includes: When the current power distribution fitness degree is greater than or equal to the previous power distribution fitness degree, the desired Fourier coefficient is determined again according to the amplitude of the desired Fourier coefficient and the current phase angle, so as to obtain the actual Fourier coefficient according to the desired Fourier coefficient, and replace the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient.

7. The method for generating an excitation signal for on-line testing of the electrochemical impedance spectrum of a new energy battery according to claim 4, wherein After updating the optimal power distribution fitness degree and the current binary sequence, the method further includes: When the optimal power distribution fitness degree is greater than or equal to the second convergence threshold, the desired Fourier coefficient is determined again according to the amplitude of the desired Fourier coefficient and the current phase angle, so as to obtain the actual Fourier coefficient according to the desired Fourier coefficient, and replace the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient.

8. The excitation signal generation method for on-line testing of the electrochemical impedance spectrum of a new energy battery according to claim 1, wherein, The outputting the optimized binary sequence includes: ； wherein, is a value that gradually approaches 0 at frequency and is used to describe the difference between the frequency-domain form of the optimized binary sequence and the expected amplitude of the specified frequency of the set of effective frequency components, is a value that gradually approaches 0 at frequency and is used to describe the difference between the frequency-domain form of the optimized binary sequence and the expected amplitude of the non-specified frequency of the set of effective frequency components, is the actual signal component amplitude of the specified frequency of the set of effective frequency components EFCS, k is the harmonic order of the signal at a fixed frequency resolution, e is the natural constant, is the imaginary unit, is the phase of the specified frequency of the set of effective frequency components EFCS.

9. An excitation signal generation device for on-line testing of the electrochemical impedance spectrum of a new energy battery, characterized in that, including: a determining unit configured to determine the desired amplitude of the specified frequency of the effective frequency component set according to the voltage noise component and the prior impedance, and determine the amplitude of the desired Fourier coefficient according to the desired amplitude of the specified frequency of the effective frequency component set and the desired amplitude of the non-specified frequency of the effective frequency component set; a repeating unit configured to repeatedly execute the following steps: determine the desired Fourier coefficient according to the amplitude of the desired Fourier coefficient and the current phase angle, perform an inverse discrete Fourier transform on the desired Fourier coefficient to obtain a time-domain signal, binarize the time-domain signal to obtain a binary sequence, perform an inverse discrete Fourier transform on the binary sequence to obtain an actual Fourier coefficient, and replace the current phase angle of the desired Fourier coefficient with the actual phase angle of the actual Fourier coefficient until a preset number of iterations; an output unit configured to output an optimized binary sequence, determine an excitation signal for online testing of the electrochemical impedance spectrum of the new energy battery according to the optimized binary sequence, so as to determine the electrochemical impedance spectrum according to the excitation signal for online testing of the electrochemical impedance spectrum of the new energy battery.

10. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the method for generating an excitation signal for online testing of the electrochemical impedance spectrum of a new energy battery according to any one of claims 1 to 8.

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