Elliptical Magnetic Field Sensor Assembly for Flat-Conductor Current
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Solution Overview
Problem
Existing current measurement technologies are highly sensitive to conductor geometries with rectangular cross-sections and varying widths, particularly in flat conductors used in busbars, leading to logistical challenges and the need for busbar-specific inventory management due to manufacturing tolerances and deviations from cylindrical symmetry.
Innovation Solution
A device using at least three magnetic field sensors arranged equidistantly along the circumference of an ellipse, without a flux concentrator, to measure the magnetic field of conductors, allowing for a more uniform distribution and reduced dependence on conductor geometry, with the sensors positioned to minimize measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a circular current transformer arrangement is used, then the measurement is theoretically symmetric, but the form factor becomes relatively large and the measurement accuracy deteriorates for flat conductors with rectangular cross-sections
Solution Approach 1:
The patent applies asymmetry by transitioning from a circular sensor arrangement to an elliptical arrangement that matches the rectangular cross-section geometry of flat conductors. The ellipse has a longer axis aligned with the conductor width, creating an asymmetric configuration that accurately captures the magnetic field distribution of non-cylindrical conductors while maintaining a compact form factor.
Solution Approach 2:
The patent implements local quality by positioning magnetic field sensors at specific locations along the elliptical circumference, with higher sensor density in regions where the magnetic field gradient is steeper (near the conductor edges). This non-uniform sensor distribution optimizes measurement accuracy for flat conductors by concentrating measurement points where they are most needed.
2Reliability
If multiple field probes are used to measure magnetic field around a conductor, then susceptibility to external fields is reduced, but the assumption of cylindrical symmetry is violated for flat conductors leading to measurement errors
Solution Approach 1:
The patent resolves this contradiction by abandoning the symmetric circular arrangement in favor of an asymmetric elliptical arrangement that conforms to the actual geometry of flat conductors. This asymmetric configuration maintains the benefit of multiple sensors for rejecting external fields while accurately representing the magnetic field distribution of rectangular cross-section conductors.
Solution Approach 2:
The patent transitions from a one-dimensional circular path to a two-dimensional elliptical path in the measurement plane. This dimensional change allows the sensor array to better capture the spatial distribution of the magnetic field around flat conductors, improving both external field rejection and measurement accuracy simultaneously.
3Measurement precision
If calibration is performed for specific busbar shapes, then measurement accuracy is optimized for those shapes, but logistical challenges arise requiring busbar-specific inventory management
Solution Approach 1:
The patent achieves universality through the elliptical sensor arrangement that can accommodate various conductor widths and aspect ratios within a single configuration. The elliptical geometry provides a flexible framework that maintains measurement accuracy across different busbar specifications, eliminating the need for multiple calibrated sensor arrays for different conductor types.
Solution Approach 2:
The patent utilizes parameter changes by allowing the elliptical arrangement dimensions (major and minor axes) to be scaled or adjusted to match different conductor geometries. This parametric flexibility enables a single sensor design to be universally applied across various busbar specifications while maintaining calibration accuracy through mathematical modeling that accounts for geometric variations.
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
Enables accurate current measurement across varying conductor widths with low dependence on geometry changes, facilitating cost-effective manufacturing and simplified calibration, and reducing measurement errors to less than 0.4% relative sensitivity error.
Implementation Method 1
device for measuring a magnetic field of a conductor of an electric current
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a device (8) for measuring a magnetic field of a conductor (1) of an electric current, the measurement of the magnetic field being carried out without using a flow concentrator. The device (8) has at least three magnetic field sensors (2). The at least three magnetic field sensors (2) are arranged on a circumference of an ellipse (4), the ellipse (4) being no circle. The at least three magnetic field sensors (2) are equidistantly arranged along the circumference of the ellipse (4).