Magnetic Modulator Demodulation for Even Harmonic DC Current Sensing
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Solution Overview
Problem
Current magnetic modulators face challenges in accurately measuring low DC currents due to significant odd harmonic components and zero-offset noises, which impair the monitoring accuracy of even harmonics, especially in high-voltage direct current (HVDC) systems.
Innovation Solution
A full even harmonic digital demodulation method based on full-phase analysis for magnetic modulators, utilizing Fourier analysis, Hamming window functions, and convolution windows to preprocess output voltage signals, effectively reducing spectrum leakage and zero-offset noises, and calculating current conversion coefficients to enhance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a double-core differential sensing structure is used in the magnetic modulator, then the measurement capability for DC currents is improved, but odd harmonic components become significantly larger than even harmonic components due to discrepancies in magnetic characteristics of the two cores
Solution Approach 1:
The patent extracts and removes the harmful odd harmonic components from the output signal through digital signal processing. By identifying the odd harmonic components as separate entities and applying cancellation algorithms, the system isolates and eliminates these harmful factors while preserving the useful even harmonic components that contain the DC current measurement information.
Solution Approach 2:
The patent converts the harmful odd harmonic components into beneficial information by using them as reference signals for cancellation. The odd harmonics, while harmful to measurement accuracy, provide a detectable pattern that can be identified and used to generate anti-phase cancellation signals, thereby transforming the harmful interference into a useful tool for improving measurement accuracy.
2Ease of manufacture
If odd harmonic components are present in the output voltage, then the magnetic modulator can operate with standard core materials, but spectral leakage from odd harmonics impairs the monitoring accuracy of even harmonics
Solution Approach 1:
The patent introduces digital signal processing algorithms as an intermediary between the magnetic modulator output and the measurement system. This intermediary layer processes the mixed signal containing both odd and even harmonics, separating and canceling the odd harmonics while preserving the even harmonics, thereby enabling accurate measurement without requiring special core materials.
3Ease of manufacture
If the hysteresis loop of the magnetic core material is asymmetric, then the magnetic modulator can function with conventional materials, but zero-offset noises at the μA level are introduced which severely affect the measurement accuracy of DC signals
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors the output signal for zero-offset noises and dynamically adjusts the cancellation parameters. By feeding back the measured offset levels and using them to refine the cancellation algorithm, the system adaptively compensates for the asymmetric hysteresis effects, maintaining high measurement accuracy despite using conventional magnetic core materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly improves measurement sensitivity and accuracy, particularly for weak DC signals, by mitigating noise interference and extracting useful components, ensuring reliable and precise current detection in high-noise environments.
Implementation Method 1
magnetic modulators offer advantages such as high resolution, high sensitivity, high precision, minimal temperature drift, and stable working characteristics, being well-suited for measuring DC currents at the level of 10 μA
Implementation Method 2
an output voltage analog signal of the magnetic modulator is converted into a digital signal by using a digital collection device
Implementation Method 3
An output voltage sequence from full-phase Fourier analysis is established based on the standard voltage timing data
Implementation Method 4
utilizing Fourier analysis, Hamming window functions, and convolution windows to preprocess output voltage signals, effectively reducing spectrum leakage
Implementation Method 5
the inherent asymmetry in the hysteresis loop of the magnetic core material introduces zero-offset noises at the μA level
Data Source
AI summary
This application relates to the field of electrical technologies, and provides a full even harmonic digital demodulation method based on full-phase analysis for a magnetic modulator. According to the full even harmonic digital demodulation method based on full-phase analysis for a magnetic modulator, standard voltage timing data output by the magnetic modulator is obtained when a DC calibration current with a set amplitude is fed into the magnetic modulator during calibration of the magnetic modulator; an output voltage sequence from full-phase Fourier analysis is established based on the standard voltage sequence data, and the output voltage sequence is preprocessed; comprehensive analysis is performed on the preprocessed output voltage sequence from full-phase Fourier analysis to obtain all standard even harmonic signals and current conversion coefficients.