AC Current Sensor With Eddy-Current Compensation
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Solution Overview
Problem
Existing current sensors struggle to accurately measure AC currents with frequencies up to 2 kHz due to the skin effect, which increases the effective resistance of electrical conductors and complicates magnetic field measurements, and require complex spectral analysis to correct for frequency-dependent errors.
Innovation Solution
A current sensor system that includes a magnetic sensor device and a conductive surface, such as a metal plate, to create a superimposed magnetic field from eddy currents, allowing for accurate measurement of AC currents without spectral analysis by determining the current as a signal proportional to the magnetic field gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic sensor device measures the magnetic field directly without additional components, then the device complexity is low, but the measurement precision deteriorates due to skin effect at high frequencies
Solution Approach 1:
A conductive plate is introduced as an intermediary component between the electrical conductor and the magnetic sensor device. This plate generates eddy currents that create a compensating magnetic field, which counteracts the skin effect and improves measurement accuracy without requiring complex signal processing or sensor modifications
Solution Approach 2:
The invention converts the harmful skin effect into a beneficial measurement mechanism. By intentionally allowing eddy currents to flow in the conductive plate, the system generates a secondary magnetic field that compensates for the skin effect's negative impact, transforming a measurement obstacle into a correction mechanism
2Measurement precision
If spectral analysis is used to correct frequency-dependent errors, then the measurement precision improves, but the device complexity and processing requirements increase
Solution Approach 1:
Instead of using complex spectral analysis to correct errors, the invention transforms the skin effect into a beneficial phenomenon. The eddy currents in the conductive plate automatically generate a compensating magnetic field that corrects frequency-dependent errors in real-time, eliminating the need for post-processing spectral analysis
Solution Approach 2:
The conductive plate performs self-correction of measurement errors through its inherent eddy current generation. The system automatically compensates for skin effect without requiring external processing units, algorithms, or complex signal analysis, making the correction mechanism self-service and hardware-based
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 system achieves accurate measurement of AC currents up to 2 kHz with improved precision and simplicity, minimizing errors caused by the skin effect without requiring heavy processing or spectral analysis.
Implementation Method 1
an electrical conductor configured for conducting said AC electrical current thereby creating a first magnetic field
Implementation Method 2
a metal plate or an electrically conductive surface arranged in the vicinity of said electrical conductor for allowing eddy currents to flow in said surface thereby creating a second magnetic field
Data Source
AI summary
A current sensor system for accurately measuring an AC electrical current having frequencies up to 2 kHz, the system comprising: an electrical conductor (e.g. busbar) for conducting said AC current thereby creating a first magnetic field; a magnetic sensor device for measuring a magnetic field component or gradient; an object (e.g. a metal plate) having an electrically conductive surface arranged in the vicinity of said conductor for allowing eddy currents to flow in said surface, thereby creating a second magnetic field which is superimposed with the first magnetic field; wherein the magnetic sensor device is configured for determining the current as a signal or value proportional to the measured component or gradient. The metal plate may have an opening. The current sensor system may further comprise a shielding.