Flux Gate Current Sensor Digital Winding Merging
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Solution Overview
Problem
Conventional flux valve current sensors face challenges in industrial reproducibility and cost due to complex analog processing and separate components for excitation, demagnetization, and measurement, which also limit their ability to handle high currents effectively.
Innovation Solution
A flux valve current sensor design that integrates a single measurement winding for both excitation and demagnetization, utilizing a digital processing chain with an FPGA for digital excitation and demagnetization signals, and an analog-to-digital converter for measurement, simplifying the structure and reducing costs while improving reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate excitation and demagnetization windings are used in conventional flux valve current sensors, then the measurement function is achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the excitation winding and demagnetization winding into a single measuring winding that performs both functions. The winding is configured with specific turn ratios to enable both excitation of the magnetic core and demagnetization compensation through digital signal processing, thereby reducing component count and device complexity while maintaining measurement reliability
Solution Approach 2:
The single measuring winding is designed to serve multiple functions: it acts as both the excitation winding and the demagnetization winding, and simultaneously serves as the measurement winding. This multi-functionality reduces the overall device complexity while maintaining the required measurement accuracy through digital signal processing
2Measurement precision
If multiple separate windings and analog processing circuits are used, then measurement functions are achieved, but manufacturing cost and production complexity increase
Solution Approach 1:
The patent replaces complex analog processing circuits with a digital processing chain implemented in an FPGA. The digital excitation signal generator, synchronous demodulator, and demagnetization control are all implemented digitally, which improves industrial reproducibility and ease of manufacture while maintaining high measurement precision through digital signal processing techniques
Solution Approach 2:
The patent changes the processing domain from analog to digital, transforming continuous analog signals into discrete digital signals for processing. This parameter change enables better industrial reproducibility through digital manufacturing techniques while maintaining measurement precision through advanced digital signal processing algorithms
3Device complexity
If a single measuring winding is used for both excitation and demagnetization, then device size and cost are reduced, but signal separation and processing become more challenging
Solution Approach 1:
The patent employs periodic square wave excitation signals at a defined frequency, and uses synchronous demodulation techniques to separate the measurement signal from excitation and demagnetization signals. The periodic nature of the excitation allows for frequency-based signal separation through synchronous detection, resolving the challenge of signal separation in the single winding configuration
Solution Approach 2:
The patent introduces digital signal processing as an intermediary between the single measuring winding and the final measurement output. The FPGA-based synchronous demodulator acts as an intermediary that separates and processes the composite signal containing measurement, excitation, and demagnetization components, enabling accurate current measurement despite the unified winding structure
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
This design simplifies the sensor, reduces size and mass, enhances industrial reproducibility, and maintains high accuracy over a wide temperature range with improved immunity to noise and electromagnetic disturbances, effectively handling high currents by optimizing the operating point and using synchronous demodulation.
Implementation Method 1
a magnetic core extending around a conductor carrying a current to be measured, a measuring winding, an excitation circuit arranged to generate a digital excitation signal
Implementation Method 2
an excitation circuit arranged to generate a digital excitation signal, and an injection circuit comprising a digital-to-analog converter arranged to produce an analog excitation current from the digital injection signal
Implementation Method 3
an acquisition circuit including an analog-to-digital converter arranged to acquire an analog measurement voltage across the measuring winding and to produce a digital measurement signal
Implementation Method 4
a demagnetization control circuit arranged to produce, from the digital measurement signal, a digital demagnetization signal intended to compensate for a magnetic flux produced by the current to be measured
Data Source
Figure 1~3
Figure 4
Figure 5~7
AI summary
A current sensor with a flux gate comprising a magnetic core (13), a measurement winding (14), an excitation circuit (23) arranged to generate a digital excitation signal (Se), an acquisition circuit (17) arranged to acquire an analogue measurement voltage (Ve) at the terminals of the measurement winding (14) and to produce a digital measurement signal (Sm), a demagnetising servo circuit (32) arranged to produce, from the digital measurement signal, a digital demagnetisation signal (Sdm) intended to compensate for a magnetic flux produced by the current to be measured, a summer (36) arranged to sum the digital excitation signal and the digital demagnetisation signal in such a way as to obtain a digital injection signal (Si), and an injection circuit (37) arranged to produce an analogue excitation current from the digital injection signal and to inject the analogue excitation current into the measurement winding.