Current Sensor Crosstalk Reduction via Sensor Array Optimization
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Solution Overview
Problem
Conventional current sensors based on magnetic cores suffer from high weight, cost, and inability to measure pure DC currents, and exhibit magnetic crosstalk due to imperfect line integration of the magnetic field, especially in multi-phase arrangements or near external currents.
Innovation Solution
The design employs an array of magnetic field sensor elements with varying sensitivities and gain factors, unequally spaced along closed paths around the conductor, allowing for electronic combination of their signals to minimize crosstalk sensitivity by optimizing sensor element configurations and gain allocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current sensors use magnetic cores with secondary windings, then they provide reliable current measurement, but they suffer from large volume, high weight, and high cost
Solution Approach 1:
The patent divides the continuous magnetic core into discrete sensor elements arranged at multiple positions around the conductor. Each sensor element measures the magnetic field at its specific location, and the individual measurements are combined through electronic addition to achieve the integrated effect that would otherwise require a continuous magnetic core. This segmentation eliminates the need for heavy magnetic core material while maintaining measurement reliability.
Solution Approach 2:
The patent replaces the mechanical magnetic core structure with an electronic system. Instead of using a physical magnetic core that requires secondary windings and iron material, the invention uses multiple magnetic field sensors whose electrical output signals are electronically combined. This substitution of mechanical components with electronic equivalents dramatically reduces weight and volume while maintaining the line integration function.
2Reliability
If magnetic core current transformers are used, then they provide stable measurement, but they cannot measure pure DC currents
Solution Approach 1:
The patent creates a measurement system that can universally handle both AC and DC currents through the same sensor array configuration. The magnetic field sensors respond to the total magnetic field regardless of whether it is generated by AC or DC current, and the electronic combination of sensor outputs maintains line integration for both current types. This eliminates the limitation of conventional current transformers that rely on electromagnetic induction, which only works for changing currents.
3Device complexity
If sensor elements are equidistantly positioned on closed paths, then the arrangement is simple and symmetric, but it results in imperfect line integration and magnetic crosstalk from external currents
Solution Approach 1:
The patent applies different characteristics to different sensor elements based on their local positions. Specifically, sensor elements are assigned different gain factors in the electronic combination process, with elements closer to potential external current sources having different weighting than those farther away. This local differentiation in gain allocation compensates for the imperfect geometric symmetry and reduces crosstalk sensitivity while maintaining overall system simplicity.
4Device complexity
If uniform gain factors are applied to all sensor elements, then the electronic combination is simple, but it cannot minimize crosstalk sensitivity
Solution Approach 1:
The patent changes the gain parameter for each sensor element based on its position in the array. By assigning different gain factors to different sensor elements, the system optimizes the weighted sum of magnetic field measurements to minimize sensitivity to external currents. This parameter variation approach allows the simple electronic combination circuit to achieve sophisticated crosstalk rejection without requiring complex processing.
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 approach results in a current sensor with reduced crosstalk, low weight, and linear characteristics, capable of accurately measuring currents while maintaining low magnetic crosstalk even with slight misalignment, combining the advantages of magnetic field integration and sensor arrays.
Implementation Method 1
sensitive to one vector component of the magnetic field generated by the electric current
Implementation Method 2
the output signal of each sensor element is amplified by an element-specific gain factor
Data Source
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AI summary
A device (1) for measuring electric current comprised of a plurality of magnetic field sensor elements (2, 2.1, 2.2,..., 2.n) positioned around a current carrying conductor, where each sensor element is sensitive to one vector component of the magnetic field generated by the electric current, where the sensor elements (2, 2.1, 2.2,..., 2.n) are positioned along one or more continuous closed paths encircling the conductor, characterized in that individual sensor elements (2, 2.1, 2.2,..., 2.n) on the same path have different sensitivities, or their output signals are amplified by different gain factors before they are combined to form the sensor signal, and/or sensor elements (2, 2.1, 2.2,..., 2.n) are non-evenly distributed along the path(s), .g. having a higher element concentration in the vicinity of a certain sensor axis and the output signals of the individual elements (2, 2.1, 2.2,..., 2.n) are electronically combined to generate the output signal of the current sensor, such that the current measuring device (1) has a much reduced crosstalk sensitivity with respect to certain current paths.