Digital demodulation of all even harmonics of a magnetic modulator based on full phase analysis

Abstract

To provide a method for digital demodulation of all even harmonics of a magnetic modulator based on full phase analysis.SOLUTION: According to the digital demodulation method for all even-order harmonics of a magnetic modulator based on full-phase analysis, when the magnetic modulator is calibrated, standard voltage time sequence data output by the magnetic modulator when a direct current calibration current of a set value flows through the magnetic modulator is obtained, an output voltage sequence of full-phase Fourier analysis is established and pre-processed according to the standard voltage time sequence data, and the pre-processed output voltage sequence of full-phase Fourier analysis is comprehensively analyzed to obtain standard even-order harmonic signals and current conversion coefficients of each order. The present invention uses the full-phase Fourier analysis technology to perform comprehensive pre-processing and comprehensive analysis on the output voltage signal of the air modulator, which greatly reduces the problems of spectrum leakage and phase disturbance, so that the data sampled at different time points are fully utilized, and the signal processing is more accurate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of electrical engineering, and in particular to a method for digital demodulation of all even harmonics of a magnetic modulator based on full phase analysis. [Background technology]

[0002] As voltage levels continue to increase, faults caused by insulation defects in HVDC equipment are becoming increasingly prominent, significantly limiting the safe and stable operation of DC power transmission systems. However, progress in online monitoring technology for monitoring the insulation status of HVDC equipment is relatively slow. This is mainly due to the relatively extreme leakage current of HVDC equipment. The most important DC leakage current amplitude is very small, with an insulation level of only 10 μA under normal circumstances. Existing non-contact current sensing technology cannot meet this requirement.

[0003] At present, non-contact DC sensing technologies mainly include Hall current sensors, magnetoresistive current sensors, and magnetic modulation current sensors, where magnetic modulation sensors have the advantages of high resolution, high sensitivity, high accuracy, small temperature drift, and stable operating characteristics, which better meet the requirements of DC current measurement at the 10μA level.

[0004] However, existing magnetic modulators typically only achieve contactless measurement of DC currents at the hundreds of microamperes level. The main reasons for the limited improvement of demodulation measurement accuracy are as follows: Even when a magnetic modulator employs a dual-core differential sensing structure, the odd-order harmonic components of the output voltage remain significantly larger than the even-order harmonics due to the mismatch in the magnetic properties of the two magnetic cores. This spectral leakage of the odd-order harmonic components impacts the monitoring accuracy of even-order harmonics. Second, due to the asymmetry of the hysteresis loop of the magnetic core material itself, microampere-level zero-point offset noise is common in magnetic modulators, which inevitably significantly impacts the measurement accuracy of tens of microamperes-level DC signals. Therefore, there is an urgent need for a high-precision digital demodulation method for magnetic modulators that can reduce the effects of odd-order harmonic spectral leakage and zero-point offset noise in magnetic modulators and further improve measurement accuracy. Summary of the Invention [Problem to be solved by the invention]

[0005] Considering the shortcomings of existing technology, the present invention provides a digital demodulation method for all even harmonics of a magnetic modulator based on full-phase analysis. This solves the problem that even if a magnetic modulator adopts a dual-core differential sensing structure, the odd-order harmonic components of the output voltage will still be much larger than the even-order harmonics due to the mismatch in the magnetic properties of the two magnetic cores. This problem of spectrum leakage of odd-order harmonic components will affect the accuracy of monitoring even-order harmonics. Secondly, due to the asymmetry of the hysteresis loop of the magnetic core material itself, microampere-level zero-point offset noise is common in magnetic modulators, which inevitably has a significant impact on the measurement accuracy of 10-microampere-level DC signals. [Means for solving the problem]

[0006] To achieve the above object, the present invention provides the following technical solution: A digital demodulation method for all even-order harmonics of a magnetic modulator based on full-phase analysis, comprising the steps of: when calibrating a magnetic modulator, a standard voltage time series data output by the magnetic modulator is obtained when a DC calibration current of a set value is passed through the magnetic modulator, the standard voltage time series data including standard output voltage signal values ​​at multiple time points; specifically, a digital acquisition device is used to convert the output voltage analog signal of the magnetic modulator into a digital signal; an output voltage sequence of full-phase Fourier analysis is established based on the standard voltage time series data, preprocessing is performed, and the preprocessed output voltage sequence of full-phase Fourier analysis is comprehensively analyzed to obtain standard even-order harmonic signals and current conversion coefficients for each order; and after the magnetic modulator is calibrated, the weak DC signal to be measured is demodulated; The weak voltage time series data to be measured, which is output by the magnetic modulator when a signal current flows through the magnetic modulator, is acquired, and a comprehensive analysis is performed to acquire the weak even-order harmonic signals to be measured at each order. The weak voltage time series data to be measured includes weak output voltage signal values ​​to be measured at multiple points in time. Specifically, a digital acquisition device is used to convert the output voltage analog signal of the magnetic modulator into a digital signal. The weak even-order harmonic signals to be measured and current conversion coefficients are comprehensively analyzed to acquire all even-order harmonic detection signals. Based on the all even-order harmonic detection signals, the measurement values ​​of the weak DC signal current to be measured are analyzed.

[0007] Furthermore, the specific steps for establishing the output voltage sequence of the full-phase Fourier analysis are as follows: 2N from the standard output voltage data of the magnetic modulator pre-processed a The standard output voltage signal value at time -1 is selected to establish the output voltage sequence for full-phase Fourier analysis, where the equation of the output voltage sequence for full-phase Fourier analysis is as follows:

[0008]

number

[0009] where Ud is the output voltage sequence of the full-phase Fourier analysis, and u d (0) is the standard output voltage signal value at the beginning of the output voltage sequence of the full-phase Fourier analysis, and u d (1) is the standard output voltage signal value at the second time point of the output voltage sequence of the full-phase Fourier analysis, and u d (2N a -1) is the standard output voltage signal value at the end of the output voltage sequence of the full phase Fourier analysis.

[0010] Furthermore, the specific steps of preprocessing the output voltage sequence of the full-phase Fourier analysis are as follows: establish a Hamming window function sequence, perform convolution analysis to obtain a convolution window sequence, and comprehensively analyze the output voltage sequence of the full-phase Fourier analysis and the convolution window sequence to obtain a sequence after full-phase preprocessing.

[0011] Furthermore, the specific steps of obtaining a convolution window sequence are as follows: a Establish a Hamming window function sequence of , and convolve it with itself to obtain 2N a - Obtain a 1-dimensional convolution window sequence, the specific formula of which is as follows:

[0012]

number

[0013] where HW(n) is the value of the Hamming window function at index n, n is the sample index within the Hamming window, and n=0, 1, 2, ..., N a -1,N a is the length of the Hamming window, GW is the convolution window sequence, and HW is the Hamming window function sequence.

[0014] Furthermore, the specific steps for obtaining the full-phase preprocessed sequence are as follows: multiply the output voltage sequence and the convolution window sequence element by element to obtain a new data sequence, and then extract the k-th and N-th terms of the new data sequence. s +k terms are added in order to obtain the full-phase preprocessed sequence.

[0015]

number

[0016] where y is the new data sequence and U d is the output voltage sequence, GW is the convolution window sequence, and U ap is the sequence after full phase preprocessing, and y(N a ), y(1), y(N a +1), y(N a -1), y(2N a -1) is the corresponding element in the new data sequence, where N a is the length of the Hamming window.

[0017] Furthermore, the specific steps for obtaining each order of standard even-order harmonic signals are as follows: perform Fourier analysis on the sequence after full phase pre-processing to obtain the total harmonic features of the standard output voltage signal, which are used to analyze each order of standard even-order harmonic signals, where the total harmonic features of the standard output voltage signal are as follows:

[0018]

number

[0019] where U d,i and φ i are the amplitude and phase of the ith harmonic, respectively, and ω e is the fundamental angular frequency of the square wave excitation source, and i=1,2,3,···,L, where L is the total number of harmonics.

[0020] Furthermore, the phasor equation for each even harmonic signal is:

[0021]

number

[0022] where: TIFF2026027169000007.tif1929 are the even harmonic signals, and U d,i and φ i are the amplitude and phase of the ith harmonic, respectively, and U dr,i and φ dr,i are the amplitudes and phases of the real even harmonics generated by the DC current, and U z,i and φ z,i is the zero-point offset noise of each even-order harmonic, where i=1,2,3,···,L, and L is the total order of the harmonics.

[0023] Furthermore, the current conversion coefficient is specifically determined by analyzing the standard even-order harmonic signal of each order and the DC calibration current, and the specific formula is as follows:

[0024]

number

[0025] where K i is the current conversion coefficient of the ith harmonic, TIFF2026027169000009.tif1929 is the even harmonic signal of the i-th harmonic, where i=1,2,3,···,L, and L is the total order of the harmonics.

[0026] Furthermore, the equation for the total even harmonic detection signal is:

[0027]

number

[0028] where: TIFF2026027169000011.tif2040 is the total even harmonic detection signal, N2 is the highest even harmonic set in the total even harmonic demodulation, and K N2 is the current conversion coefficient when the highest even harmonic is set in all even harmonic demodulation, TIFF2026027169000012.tif1417 is a weak even harmonic signal to be measured when it is the highest even harmonic set in all even harmonic demodulation.

[0029] Furthermore, the specific calculation formula for analyzing the measurement value of the weak DC signal current to be measured is as follows:

[0030]

number

[0031] where I m is the measurement value of the weak DC signal current to be measured, TIFF2026027169000014.tif2040 is the all even harmonic detection signal, and N2 is the highest even harmonic set in all even harmonic demodulation. [Effects of the Invention]

[0032] The present invention has the following beneficial effects: (1) This method for digitally demodulating all even-order harmonics of a magnetic modulator based on full-phase analysis uses full-phase Fourier analysis technology to perform comprehensive pre-processing and comprehensive analysis on the output voltage signal of the magnetic modulator, thereby significantly reducing the problems of spectral leakage and phase disturbance. Therefore, the data sampled at different times is fully utilized, and the signal processing is more accurate. In particular, the use of a Hamming window function and a convolution window sequence in pre-processing effectively smooths the sudden changes in the signal boundary, significantly reducing the impact of edge effects on spectral analysis, thereby improving the accuracy and reliability of the measurement results.

[0033] (2) This method for digitally demodulating all even harmonics of a magnetic modulator based on full phase analysis utilizes the uniformity of the phases of the real even harmonics caused by the DC calibration current and the dispersion of the zero-point offset noise phase of each even harmonics. By calculating the current conversion coefficient and converting the detection signals of each even harmonic, the influence of the zero-point offset noise can be effectively suppressed. This significantly improves measurement sensitivity and accuracy, especially in detecting weak signals such as 10 μA level DC signals. This improvement is very important for high-precision measurement devices, especially for use in high-voltage DC power transmission systems.

[0034] (3) This method for digitally demodulating all even-order harmonics of a magnetic modulator based on full-phase analysis comprehensively analyzes all even-order harmonic detection signals and accurately calculates current conversion coefficients, thereby effectively extracting useful components from weak signals and avoiding measurement errors caused by insufficient sensitivity of the device. In particular, by analyzing the full-phase harmonic characteristics of the weak DC signal current being measured, it is possible to accurately capture changes in weak signals even in high-noise environments. Such highly sensitive measurement capabilities play an important role in accurately monitoring and evaluating the operating status of equipment in modern power systems, allowing for timely detection and warning of potential faults.

[0035] Of course, a product embodying the present invention need not necessarily achieve all of the above advantages simultaneously. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a flowchart of a method for digitally demodulating all even-order harmonics of a magnetic modulator based on full phase analysis according to the present invention. [Figure 2] 1 is a flowchart of one embodiment of a method for digitally demodulating all even-order harmonics of a magnetic modulator based on full phase analysis according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] The embodiment of this application uses a digital demodulation method for all even harmonics of a magnetic modulator based on full phase analysis. This solves the problem that even if the magnetic modulator adopts a dual magnetic core differential sensing structure, the odd harmonic components of the output voltage will still be much larger than the even harmonics due to the mismatch in the magnetic properties of the two magnetic cores. This problem of spectrum leakage of odd harmonic components will affect the monitoring accuracy of even harmonics. Secondly, due to the asymmetry of the hysteresis loop of the magnetic core material itself, zero-point offset noise at the μA level is common in magnetic modulators, which inevitably has a serious impact on the measurement accuracy of 10 μA level DC signals.

[0038] The general approach to the problem in the examples of this application is as follows. A set DC calibration current is passed through the magnetic modulator to obtain the standard voltage time series data output by the magnetic modulator. A digital acquisition device is used to convert the output voltage analog signal into a digital signal to obtain the standard output voltage signal value. In the establishment and pre-processing of the output voltage sequence ("sequence" in the original Chinese is "sequence") for full-phase Fourier analysis, the output voltage sequence for full-phase Fourier analysis is established based on the standard voltage time series data. Pre-processing is performed on the output voltage sequence, including establishing a Hamming window function sequence and performing convolution analysis to obtain the convolution window sequence. A comprehensive analysis of the output voltage sequence and the convolution window sequence is performed to obtain the full-phase pre-processed sequence. In the Fourier analysis and calculation of the current conversion coefficients, , a Fourier analysis is performed on the sequence after full phase preprocessing to obtain standard even-order harmonic signals of each order, and the current conversion coefficients between the standard even-order harmonic signals of each order and the DC calibration current are calculated. In the acquisition and analysis of the signal to be measured, the weak DC signal current to be measured is passed through a magnetic modulator to obtain time series data of the weak voltage to be measured, and a digital acquisition device is used to convert the output voltage analog signal into a digital signal to obtain the weak output voltage signal value to be measured. In the calculation of all even-order harmonic detection signals and the current to be measured, the weak even-order harmonic signals to be measured and the current conversion coefficients are comprehensively analyzed to obtain all even-order harmonic detection signals, and the measurement value of the weak DC signal current to be measured is calculated based on all even-order harmonic detection signals.

[0039] Referring to Fig. 1, an embodiment of the present invention provides the following technical solution: A method for digitally demodulating all even-order harmonics of a magnetic modulator based on full-phase analysis, comprising the steps of: when calibrating a magnetic modulator, obtaining standard voltage time series data output by the magnetic modulator when a DC calibration current of a set value is passed through the magnetic modulator, the standard voltage time series data including standard output voltage signal values ​​at multiple time points; specifically, using a digital acquisition device to convert the output voltage analog signal of the magnetic modulator into a digital signal; establishing an output voltage sequence of full-phase Fourier analysis based on the standard voltage time series data, performing preprocessing; comprehensively analyzing the preprocessed output voltage sequence of full-phase Fourier analysis to obtain standard even-order harmonic signals and current conversion coefficients for each order; and after the magnetic modulator is calibrated, obtaining a weak voltage to be measured output by the magnetic modulator when a weak DC signal current to be measured is passed through the magnetic modulator. The weak even-order harmonic signals to be measured are acquired, and a comprehensive analysis is performed, including a step of establishing an output voltage sequence through full-phase Fourier analysis, a preprocessing step, and a step of comprehensively analyzing the output voltage sequence after the preprocessing of the full-phase Fourier analysis, to acquire weak even-order harmonic signals to be measured at each order. The weak voltage time-series data to be measured includes weak output voltage signal values ​​to be measured at multiple points in time. Specifically, a digital acquisition device is used to convert the output voltage analog signal of the magnetic modulator into a digital signal. The weak even-order harmonic signals to be measured and current conversion coefficients are comprehensively analyzed to acquire all even-order harmonic detection signals. Based on the all even-order harmonic detection signals, measured values ​​of the weak DC signal current to be measured are analyzed.

[0040] Specifically, the specific steps for establishing the output voltage sequence of the full-phase Fourier analysis are as follows: 2N from the standard output voltage data of the magnetic modulator after preprocessing a The standard output voltage signal value at time -1 is selected to establish the output voltage sequence for full-phase Fourier analysis, where the equation of the output voltage sequence for full-phase Fourier analysis is as follows:

[0041]

number

[0042] where U d is the output voltage sequence of the full-phase Fourier analysis, and u d (0) is the standard output voltage signal value at the beginning of the output voltage sequence of the full-phase Fourier analysis, and u d (1) is the standard output voltage signal value at the second time point of the output voltage sequence of the full-phase Fourier analysis, and u d (2N a -1) is the standard output voltage signal value at the end of the output voltage sequence of the full phase Fourier analysis.

[0043] In this embodiment, the establishment of an output voltage sequence for full-phase Fourier analysis can greatly improve the accuracy of spectral analysis. By selecting pre-processed voltage signal data and performing full-phase Fourier analysis, spectral leakage caused by signal edge effects can be reduced. Specifically, the full-phase processing of the standard output voltage signal value makes full use of the signal at each time point, resulting in more accurate Fourier transform results. This is important for high-precision signal analysis and detection, and can greatly improve the detection sensitivity and reliability, especially when detecting weak signals. The establishment of an output voltage sequence for full-phase Fourier analysis can improve the robustness of signal processing. The full-phase Fourier analysis method takes into account the phase information of the signal at different times, making the entire signal processing process more resistant to noise and interference. This method can better capture the essential characteristics of the signal, especially in the presence of zero-point offset noise, through comprehensive analysis and preprocessing, the impact of noise on signal measurement can be effectively suppressed, and the stability and reliability of the entire signal processing system can be improved. This method lays a solid foundation for subsequent harmonic analysis and current measurement. By establishing the output voltage sequence of full-phase Fourier analysis, each order of harmonic components can be more accurately extracted, especially the even-order harmonic components. In the subsequent step, through Fourier analysis and calculation of current conversion coefficients, the current value of the weak DC signal to be measured can be more accurately measured. The optimized signal processing process improves measurement accuracy and further simplifies the measurement steps, improving the efficiency and reliability of the entire measurement process, and is suitable for the application of high-precision current detection.

[0044] Specifically, the specific steps of preprocessing the output voltage sequence of the full-phase Fourier analysis are as follows: establish a Hamming window function sequence, perform convolution analysis to obtain a convolution window sequence, and comprehensively analyze the output voltage sequence of the full-phase Fourier analysis and the convolution window sequence to obtain a sequence after full-phase preprocessing.

[0045] In this embodiment, by establishing a Hamming window function and performing convolution analysis, the problem of spectral leakage in signal processing can be effectively alleviated. The application of the Hamming window function can smooth the signal edges and reduce the impact of spectral leakage caused by window truncation. The convolution window sequence further enhances this effect, making the spectral analysis results of the Fourier transform more accurate. This preprocessing method can ensure that the signal representation in the frequency domain is closer to the actual situation and can reduce errors caused by boundary effects. Especially in high-precision measurement and analysis, this improvement greatly improves the reliability of the results. The preprocessing step of full-phase Fourier analysis, including convolution analysis with a Hamming window, can improve the robustness of signal processing. The Hamming window function reduces high-frequency noise and boundary effects in the signal, making the processed signal smoother and easier to analyze. After full-phase preprocessing, The sequence preserves the important features of the signal while suppressing noise and interference, making the subsequent Fourier analysis and harmonic extraction more accurate. This method is particularly suitable for accurate signal measurement in high-noise environments and helps improve the stability and reliability of the entire system. After Hamming window function preprocessing and convolution analysis, the output voltage sequence of the full-phase Fourier analysis is smoothed and many interference factors are removed. This preprocessing helps optimize the subsequent harmonic analysis and current measurement. The preprocessed signal is clearer, making it easier to identify and analyze the harmonic components, which allows for more accurate calculation of the current conversion coefficients and extraction of each even-order harmonic signal. This not only improves measurement accuracy, but also simplifies the signal processing process, making the entire measurement process more efficient and reliable. It is particularly suitable for high-precision current detection applications, such as the accurate measurement of weak DC signals.

[0046] Specifically, the specific steps of obtaining a convolution window sequence are as follows: a Establish a Hamming window function sequence of , and convolve it with itself to obtain 2N a - Obtain a 1-dimensional convolution window sequence, the specific formula of which is as follows:

[0047]

number

[0048] where HW(n) is the value of the Hamming window function at index n, n is the sample index within the Hamming window, and n=0, 1, 2, ..., Na-1, Na is the length of the Hamming window, GW is the convolution window sequence, and HW is the Hamming window function sequence.

[0049] In this embodiment, the Hamming window function sequence, due to its special weighting method, can effectively alleviate the problem of spectral leakage in Fourier transform. The convolution window sequence further smooths the signal and greatly reduces the impact of edge effects on the spectrum. This smoothing process ensures that the signal representation in the frequency domain is more true and accurate, and reduces the aliasing phenomenon caused by signal truncation. This is very important for applications requiring high-precision spectrum analysis, such as high-precision current measurement and signal processing. The convolution window sequence and the Hamming window function sequence further improve the robustness of signal processing by convolution operation. This processing method can suppress high-frequency noise and edge effects in the signal, making the processed signal smoother and more stable. By combining full-phase Fourier analysis with a convolution window sequence, the essential characteristics of the signal can be captured more effectively. This improves the anti-interference capability of signal processing, especially in noise and interference environments, thereby improving the stability and reliability of the entire system. By preprocessing the output voltage sequence of full-phase Fourier analysis and using a convolution window sequence, the harmonic components in the signal can be more accurately extracted. The application of a convolution window sequence makes the harmonic characteristics of the signal clearer and easier to analyze, allowing for more accurate calculation of the current conversion coefficients and extraction of each even-order harmonic signal. This optimization process not only improves measurement accuracy, but also simplifies the signal processing process, making the entire measurement process more efficient and reliable. This is particularly suitable for high-precision current detection applications, such as the accurate measurement of weak DC signals.

[0050] Specifically, the specific steps for obtaining the full-phase preprocessed sequence are as follows: multiply the output voltage sequence and the convolution window sequence element by element to obtain a new data sequence, and then divide the k-th and N-th terms of the new data sequence into s +k terms are added in order to obtain the full-phase preprocessed sequence.

[0051]

number

[0052] where y is the new data sequence and U d is the output voltage sequence, GW is the convolution window sequence, and U ap is the sequence after full phase preprocessing, and y(N a ), y(1), y(N a +1), y(N a -1), y(2N a -1) is the corresponding element in the new data sequence, where N a is the length of the Hamming window, from 1 to 2N a -1 covers the entire windowed sequence, and N s ≦N a is.

[0053] In this embodiment, the output voltage sequence and the convolution window sequence are multiplied element by element, which effectively combines the frequency domain and time domain characteristics of the signal and reduces the spectral leakage caused by edge effects. This processing method ensures the accuracy of the Fourier transform result. Each data point in the signal is smoothed, reducing the impact of high-frequency noise and other interference, improving the accuracy and reliability of signal processing. This is important for high-precision current measurement and signal analysis. In particular, in scenarios requiring high accuracy, the full-phase preprocessing sequence can effectively improve the robustness of the signal. The element-by-element multiplication and addition processing method fully considers each part of the signal, making the processed signal smoother and more stable. This can better capture the essential characteristics of the signal and reduce the impact of noise and interference. , especially in the presence of zero-point offset noise, noise interference with signal measurement can be greatly suppressed, improving the stability and anti-interference capability of the entire system. By performing a pre-processing step of element-by-element multiplication and addition of the output voltage sequence and the convolution window sequence, the subsequent harmonic analysis and current measurement can be greatly optimized. The sequence after full-phase pre-processing more clearly reflects the harmonic characteristics of the signal, allowing each order of harmonic components to be more accurately extracted by Fourier transform. This optimization process improves the accuracy of harmonic analysis and further simplifies the signal processing process, making the entire measurement process more efficient and reliable, particularly suitable for accurate measurement of weak DC signals and high-precision current detection. This pre-processing method also allows the current conversion coefficient to be calculated more accurately, improving the sensitivity and accuracy of current measurement.

[0054] Specifically, the specific steps for obtaining each order of standard even-order harmonic signals are as follows: Fourier analysis is performed on the sequence after full phase pre-processing to obtain the total harmonic features of the standard output voltage signal, which are used to analyze each order of standard even-order harmonic signals, where the total harmonic features of the standard output voltage signal are as follows:

[0055]

number

[0056] where U d,i and φ i are the amplitude and phase of the ith harmonic, respectively, and ω e is the fundamental angular frequency of the square wave excitation source, and i=1,2,3,···,L, where L is the total number of harmonics.

[0057] In this embodiment, by performing Fourier analysis on the sequence after full-phase preprocessing, the frequency components of the signal, including the amplitude and phase of each harmonic, can be accurately extracted. This extraction method can reliably capture the subtle characteristics of the signal at different frequencies. Especially for complex signals with multiple harmonic components, this analysis method can accurately identify and separate each even-order harmonic signal, thereby providing a deeper understanding of the frequency characteristics and dynamic changes of the signal and improving the accuracy and reliability of spectral analysis. The full-phase Fourier analysis method significantly improves the sensitivity of harmonic analysis. The signal sequence after full-phase preprocessing retains the complete phase information of the signal and reduces the influence of edge effects, so Fourier analysis has a higher sensitivity for detecting weak harmonic components. This high Sensitivity analysis is crucial for detecting and analyzing the harmonic characteristics of weak DC signals, helping to improve signal measurement accuracy. Particularly in applications such as low-current measurement and high-precision signal analysis, extracting the amplitude and phase of each standard even-order harmonic signal allows for a more accurate description of the signal's full harmonic characteristics. This method effectively suppresses the effects of noise and interference on signal measurement, ensuring stable and reliable measurement results. Combining full-phase Fourier analysis with Hamming window preprocessing fully addresses the signal's edge effects, reducing spectral leakage and phase disturbance, and improving signal measurement accuracy. This processing method is particularly suitable for high-precision current detection and analysis of weak signals, significantly improving the performance and reliability of the entire measurement system.

[0058] Specifically, the phasor equation of each even harmonic signal is as follows:

[0059]

number

[0060] where: TIFF2026027169000020.tif1929 are the even harmonic signals, and U d,i and φ i are the amplitude and phase of the ith harmonic, respectively, and U dr,i and φ dr,i are the amplitudes and phases of the real even harmonics generated by the DC current, and U z,i and φ z,i is the zero-point offset noise of each even-order harmonic, where i=1,2,3,···,L, and L is the total order of the harmonics.

[0061] In this embodiment, each even-order harmonic signal is decomposed into a real even-order harmonic component and a zero-point offset noise component, which can more accurately separate the useful information and noise in the signal. The real even-order harmonic component represents the effective signal generated by the DC current, and the zero-point offset noise component represents the noise interference in the signal. This separation method can effectively suppress the influence of noise in signal processing, thereby improving the accuracy and reliability of measurement, which is particularly important for detecting weak signals and measuring with high precision. By analyzing the phasors of each even-order harmonic signal, the robustness and stability of signal processing can be improved. The phasor formula provides information on the amplitude and phase of the signal, so that the true characteristics of the signal, the amplitude and phase of the real even-order harmonic component, can be determined even in a noisy or interference environment. The uniformity of the zero-point offset noise and the phase dispersion of the zero-point offset noise can be accurately captured and more clearly reflected through the phasor equation, which effectively suppresses noise interference in signal processing and ensures the stability and consistency of the signal processing process. The phasor equation for each even-order harmonic signal makes harmonic analysis and current measurement more accurate. By decomposing the real harmonic components and noise components in the signal, harmonic characteristics can be more accurately extracted and analyzed, and more accurate current conversion coefficients can be calculated. This method not only improves the accuracy of harmonic analysis, but also optimizes the current measurement process, allowing weak DC signals to be more accurately measured in high-precision current detection applications, improving the overall performance and reliability of the measurement system.

[0062] Specifically, the current conversion coefficient is specifically determined by analyzing each standard even-order harmonic signal and the DC calibration current, and the specific formula is as follows:

[0063]

number

[0064] where K i is the current conversion coefficient of the ith harmonic, TIFF2026027169000022.tif1929 is the even harmonic signal of the i-th harmonic, where i=1,2,3,···,L, and L is the total order of the harmonics.

[0065] In this embodiment, the voltage signal of each harmonic order can be converted into a corresponding current signal by calculating the current conversion coefficient. The current conversion coefficient is calculated from the known calibration current and the measured harmonic signal. This conversion method ensures the accuracy of the signal measurement. The calibration process eliminates the influence of instrument errors and environmental factors on the measurement results, thereby improving the accuracy of current measurement. This is especially important for detecting weak signals, as small errors can have a significant impact on the measurement results. The introduction of the current conversion coefficient simplifies the analysis process of complex signals. After each harmonic signal is converted into a current, it can be compared and analyzed more intuitively. Especially when multiple harmonic components are mixed, using the conversion coefficient to normalize the signals of different frequency components can more accurately identify different harmonic components. This simplifies the signal processing and analysis steps and improves signal processing efficiency. The current conversion coefficient is calculated based on the standard even-order harmonic signal and DC calibration current, ensuring the robustness and stability of the measurement system. The calibration process can compensate for nonlinearity and drift within the system, making measurement results more stable and reliable. The introduction of the current conversion coefficient provides a consistent conversion reference even under different measurement conditions, reducing the impact of environmental changes on measurement results and improving overall system performance. This is particularly important for high-precision current detection and long-term monitoring applications, as it ensures that the measurement system maintains high consistency and reliability over a wide range of operating conditions.

[0066] Specifically, the equation for the total even harmonic detection signal is:

[0067]

number

[0068] where: TIFF2026027169000024.tif2040 is the total even harmonic detection signal, N2 is the highest even harmonic set in the total even harmonic demodulation, and K N2is the current conversion coefficient when the highest even harmonic is set in all even harmonic demodulation, TIFF2026027169000025.tif2024 is a weak even harmonic signal to be measured when it is the highest even harmonic set in all even harmonic demodulation.

[0069] In this embodiment, the calculation method of the total even harmonic detection signal can comprehensively consider the contribution of different orders of even harmonic signals to the entire signal. Each even harmonic signal is normalized according to its current conversion coefficient and then accumulated to obtain the total even harmonic detection signal, thereby eliminating the amplitude difference between different frequency components and improving the accuracy and stability of signal detection. Especially in complex signal environments, the target signal can be more accurately identified and extracted, and the sensitivity and reliability of measurement are improved. By calculating the total even harmonic detection signal, the impact of zero-point offset noise on signal detection can be greatly reduced. Zero-point offset noise often affects measurement accuracy, especially in the detection of weak signals. By normalizing and weighting the even harmonic signals, This effectively suppresses noise interference with the detection signal, thereby improving the robustness and interference resistance of the measurement system. This method allows weak signals to be accurately detected even in noisy environments. The method for calculating all even-order harmonic detection signals optimizes the signal processing process and improves measurement efficiency. Normalizing and weighting each even-order harmonic signal not only simplifies the signal processing step, but also improves the speed and efficiency of data processing. The calculation results of all even-order harmonic detection signals can be directly used in subsequent current measurement and signal analysis, reducing the complexity of intermediate processes. This optimized processing method not only improves the system response speed, but also enables high-precision measurement results to be obtained quickly, making it suitable for real-time monitoring and efficient measurement applications.

[0070] Specifically, the specific calculation formula for analyzing the measurement value of the weak DC signal current to be measured is as follows:

[0071]

number

[0072] where I m is the measurement value of the weak DC signal current to be measured, TIFF2026027169000027.tif2040 is the all even harmonic detection signal, and N2 is the highest even harmonic set in all even harmonic demodulation.

[0073] In this embodiment, the formula is used to calculate the measurement value of the weak DC signal current to be measured, thereby greatly improving the accuracy and sensitivity of weak signal measurement. The absolute value of the total even-order harmonic detection signal reflects the intensity of the effective harmonic components in the signal, and by normalizing and weighting it, the effective current component of the weak signal can be accurately extracted. This method is particularly suitable for detecting and measuring weak DC signals and can ensure the accuracy of measurement results in high-precision measurement applications. The formula is used to calculate the total even-order harmonic detection signal with the current conversion coefficients of the set highest even-order harmonic and the second even-order harmonic, which simplifies the measurement process and improves measurement efficiency. The formula is a method for converting the total even-order harmonic detection signal into an actual current measurement value. This method directly provides a method to eliminate tedious intermediate steps and complex calculation processes. This simplified processing method improves the system's response speed and measurement efficiency, making it suitable for real-time monitoring and efficient measurement applications. Normalizing the full even-order harmonic detection signal effectively reduces the impact of noise and interference on measurement results, improving the stability and reliability of the measurement system. Measurements calculated using this formula can maintain high accuracy and consistency, especially in high-noise environments. The full even-order harmonic detection signal integrates information from multiple harmonic components. Applying a standardized current conversion coefficient and the highest even-order harmonic further improves the robustness and interference resistance of the measurement system and ensures the reliability of measurement results under different conditions.

[0074] Referring to FIG. 2, a specific example of a digital demodulation method for all even-order harmonics of a magnetic modulator based on full phase analysis is as follows. Step 1: During the first measurement, apply a 10mA DC calibration current, I ca is fed to the magnetic modulator. Step 2: Use a digital acquisition device to convert the output voltage analog signal into a digital signal, obtain the time series data of the output voltage signal, and use 19999 time series data to perform full-phase Fourier analysis of the output voltage sequence U d Build. Step 3: Construct a Hamming window function sequence HW of length 10000, calculate a convolution window sequence GW, and then multiply the output voltage sequence Ud by the convolution window sequence GW element by element, and sequentially add the kth term and the Ns+kth term to obtain a full-phase preprocessed sequence U ap Get. Step 4: Sequence U ap Perform a Fourier analysis on the total height of the output voltage signal Harmonic features are obtained and based on this, each even harmonic signal TIFF2026027169000028.tif1929 is calculated, and in this embodiment, only harmonics up to the 8th order are considered.

[0075]

number

[0076] Step 5: As can be seen from the above equation, the zero-point offset noise of the magnetic modulator is about 100 μA level, and the 10 mA DC calibration current I ca Therefore, at this point, the current conversion coefficient K i can be calculated as follows:

[0077]

number

[0078] Step 6: After the calibration is complete, apply a weak DC signal current of 0.1 mA to be measured. p is sent to the magnetic modulator, and the even-order harmonic detection signal at this time is TIFF2026027169000031.tif1929 is as follows:

[0079]

number

[0080] In this case, as can be seen from the above equation, the zero-point offset noise of the magnetic modulator has a significant effect on the measurement accuracy of a weak DC signal of 0.1 mA.

[0081] Step 7: Each even harmonic detection signal TIFF2026027169000033.tif1929 current conversion coefficient K i and converts it according to the total even harmonic detection signal Calculate TIFF2026027169000034.tif2040 as follows:

[0082]

number

[0083] Step 8: The total even harmonic detection signal Using TIFF2026027169000036.tif2040, the weak DC signal current I p Measurements of I m is calculated as follows:

[0084]

number

[0085] The all even-order harmonic digital demodulation method of the present invention can greatly weaken the influence of zero-point offset noise, and further improve the measurement sensitivity and accuracy of the magnetic modulator.

[0086] In summary, the present application has at least the following effects: Using full-phase Fourier analysis technology, the magnetic modulator output voltage signal is fully pre-processed and comprehensively analyzed, greatly reducing the problems of spectral leakage and phase disturbance. Data sampled at different times is fully utilized, making signal processing more accurate. In particular, the use of a Hamming window function and a convolution window sequence in pre-processing effectively smooths the sudden changes in the signal boundary, greatly reducing the impact of edge effects on spectral analysis, thereby improving the accuracy and reliability of the measurement results.

[0087] By utilizing the uniform phase of the real even harmonics caused by the DC calibration current and the dispersion of the zero-offset noise phase of each even harmonic, the influence of the zero-offset noise can be effectively suppressed by calculating the current conversion coefficient and converting each even harmonic detection signal, thereby significantly improving measurement sensitivity and accuracy, especially in detecting weak signals such as 10μA level DC signals. Such improvements are very important for high-precision measurement equipment, especially for use in high-voltage DC power transmission systems.

[0088] By comprehensively analyzing all even-order harmonic detection signals and accurately calculating the current conversion coefficients, useful components can be effectively extracted from weak signals, avoiding measurement errors caused by insufficient device sensitivity. In particular, by analyzing the full-phase harmonic characteristics of the weak DC signal current being measured, changes in weak signals can be accurately captured even in high-noise environments. Such highly sensitive measurement capabilities play an important role in accurately monitoring and evaluating the operating status of equipment in modern power systems, allowing for timely detection and warning of potential faults.

[0089] Although preferred embodiments of the present invention have been described, those skilled in the art will be able to make further changes and modifications to these embodiments once they understand the basic inventive concept. It is therefore intended that the appended claims be interpreted to include not only the preferred embodiments but also all changes and modifications that fall within the scope of the present invention.

[0090] Of course, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their technical equivalents, the present invention is intended to cover these modifications and variations as well.

Claims

1. When calibrating a magnetic modulator, a step of acquiring standard voltage time series data output by the magnetic modulator when a DC calibration current of a set value is passed through the magnetic modulator, the standard voltage time series data including standard output voltage signal values ​​at a plurality of points in time; Establishing an output voltage sequence of a full-phase Fourier analysis based on the standard voltage time series data and performing preprocessing; Comprehensively analyzing the pre-processed output voltage sequence of the full-phase Fourier analysis to obtain standard even-order harmonic signals and current conversion coefficients of each order; After the magnetic modulator is calibrated, a step of acquiring weak voltage time series data to be measured output from the magnetic modulator when a weak DC signal current to be measured flows through the magnetic modulator, and performing a comprehensive analysis to acquire weak even-order harmonic signals to be measured for each order, wherein the weak voltage time series data to be measured includes weak output voltage signal values ​​to be measured at multiple points in time; a step of comprehensively analyzing the weak even-order harmonic signals to be measured for each order and the current conversion coefficients to obtain all even-order harmonic detection signals; A digital demodulation method for all even-order harmonics of a magnetic modulator based on full phase analysis, comprising a step of analyzing measured values ​​of the weak DC signal current to be measured based on the all even-order harmonics detection signal.

2. 2N from the standard voltage time series data of the magnetic modulator that has been preprocessed ａ 2. The digital demodulation method for all even-order harmonics of a magnetic modulator based on full phase analysis according to claim 1, wherein a standard output voltage signal value at time point -1 is selected to establish an output voltage sequence for the full phase Fourier analysis using the following equation: [Equation 1] Here, U ｄ is the output voltage sequence of the full-phase Fourier analysis, and u ｄ (0) is the standard output voltage signal value at the beginning of the output voltage sequence of the full phase Fourier analysis, and u ｄ (1) is the standard output voltage signal value at the second time point of the output voltage sequence of the full-phase Fourier analysis, and u ｄ (2N ａ −1) is the standard output voltage signal value at the end of the output voltage sequence of the full phase Fourier analysis.

3. The step of pre-processing the output voltage sequence for full phase Fourier analysis comprises: Establishing a Hamming window function sequence and performing convolution analysis to obtain a convolution window sequence; The digital demodulation method for all even-order harmonics of a magnetic modulator based on full-phase analysis according to claim 1, characterized in that the output voltage sequence of the full-phase Fourier analysis and the convolution window sequence are analyzed comprehensively to obtain a sequence after full-phase preprocessing.

4. In the step of obtaining the convolution window sequence, the following formula 2 is used: Length is N ａ and convolving it with itself to obtain 2N ａ The digital demodulation method for all even-order harmonics of a magnetic modulator based on total phase analysis according to claim 3, characterized in that the convolution window sequence is acquired in a -1-dimensional manner. [Equation 2] where HW(n) is the value of the Hamming window function at index n, n is the sample index in the Hamming window, and n=0, 1, 2, . . . , N ａ -1, N ａ is the length of the Hamming window, GW is the convolution window sequence, and HW is the Hamming window function sequence.

5. In the step of acquiring the sequence after all phase preprocessing, the following formula 3 is used: element-wise multiplying the output voltage sequence and the convolution window sequence to obtain a new data sequence, and ｓ The digital demodulation method for all even-order harmonics of a magnetic modulator based on total phase analysis according to claim 4, characterized in that the +k terms are added in order to obtain the sequence after the total phase preprocessing. [Equation 3] where y is the new data sequence and U ｄ is the output voltage sequence, GW is the convolution window sequence, and U ａｐ is the sequence after full phase preprocessing, and y(N ａ ), y(1), y(N ａ +1), y(N ａ −1), y(2N ａ −1) is the corresponding element in the new data sequence, where N ａ is the length of the Hamming window.

6. In the step of acquiring the standard even-order harmonic signals of each order, 2. The digital demodulation method for all even-order harmonics of a magnetic modulator based on full-phase analysis according to claim 1, wherein a Fourier analysis is performed on the sequence after the full-phase preprocessing to obtain the full harmonic features of the standard output voltage signal shown in the following equation (4), and the full harmonic features are used to analyze the standard even-order harmonic signals of each order. [Equation 4] Here, U ｄ，ｉ and φ ｉ are the amplitude and phase of the i-th harmonic, respectively, and ω ｅ is the fundamental angular frequency of the square wave excitation source, and i=1, 2, 3, . . . , L, L is the total number of harmonics.

7. The digital demodulation method for all even-order harmonics of a magnetic modulator based on total phase analysis according to claim 6, characterized in that the even-order harmonic signals at each order are expressed by a phasor equation shown in the following equation (5). [Equation 5] where: 【number】 are the even harmonic signals, and U ｄ，ｉ and φ ｉ are the amplitude and phase of the i-th harmonic, respectively, and U ｄｒ，ｉ and φ ｄｒ，ｉ are the amplitude and phase of the real even-order harmonics generated by the DC current, and U ｚ，ｉ and φ ｚ，ｉ is the zero-point offset noise of each even-order harmonic, and i=1, 2, 3, . . . , L, where L is the total order of the harmonics.

8. 8. The digital demodulation method for all even-order harmonics of a magnetic modulator based on total phase analysis according to claim 7, wherein the current conversion coefficients are determined by analyzing the standard even-order harmonic signals of each order and the DC calibration currents using the following equation (6): [Equation 6] Here, K ｉ is the current conversion coefficient of the i-th harmonic, 【number】 is the even harmonic signal of the i-th harmonic, where i=1, 2, 3, ..., L, L is the total order of the harmonics, and I ｃａ is the DC calibration current.

9. 9. The digital demodulation method for all even-order harmonics of a magnetic modulator based on total phase analysis according to claim 8, wherein the all even-order harmonics detection signal is expressed by the following equation (7). [Equation 7] where: 【number】 is the total even harmonic detection signal, and N ２ is the highest even harmonic set in all even harmonic demodulation, and K Ｎ２ is the current conversion coefficient when the highest even harmonic is set in all even harmonic demodulation, 【number】 is a weak even harmonic signal to be measured when it is the highest even harmonic set in all even harmonic demodulation.

10. 10. The digital demodulation method for all even-order harmonics of a magnetic modulator based on total phase analysis according to claim 9, wherein the measured value of the weak DC signal current to be measured is analyzed using the following equation (8): [Equation 8] Here, I ｍ is the measurement value of the weak DC signal current to be measured, 【number】 is the total even harmonic detection signal, and N ２ is the highest even harmonic of the setting in all even harmonic demodulation.

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