Differential Current Sensor Layout for Shieldless Noise Rejection
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Solution Overview
Problem
Current sensing technologies face challenges in accurately measuring fast-varying electrical currents due to induced voltages from magnetic flux, leading to measurement errors and potential malfunctions, and require additional magnetic shields that increase device footprint.
Innovation Solution
A magnetic field sensor configuration with sensing elements separated in directions perpendicular to the current, combined with magnetic concentrators, reduces electromagnetic noise without the need for large shields by using redundant signals and gradient measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic shields are used to reduce magnetic noise influence, then measurement accuracy is improved, but device footprint increases
Solution Approach 1:
The patent extracts and removes the magnetic shield component from the sensor assembly, replacing it with a shieldless design that uses signal processing and sensor configuration to achieve noise rejection without the physical shield, thereby reducing device footprint while maintaining measurement accuracy
Solution Approach 2:
The patent replaces the mechanical magnetic shield with an electronic/software-based solution involving differential sensing, signal processing algorithms, and sensor fusion to achieve magnetic noise rejection without physical barriers, reducing the device footprint
2Device complexity
If traditional single-point sensing is used, then device complexity is reduced, but measurement precision of fast-varying currents deteriorates due to induced voltages
Solution Approach 1:
The patent segments the sensing function into multiple spatially distributed sensing elements arranged in specific geometries (e.g., gradiometer configurations with multiple sensors at different positions), which enables differential measurement that rejects induced voltages while maintaining manageable device complexity
Solution Approach 2:
The patent introduces signal processing algorithms and processing circuits as intermediaries that take inputs from multiple sensing elements and compute differential or gradiometer signals, thereby eliminating induced voltage errors through mathematical processing rather than requiring complex hardware modifications
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 sensor provides enhanced immunity to electromagnetic noise, improving signal-to-noise ratio (SNR) and mechanical tolerances, allowing accurate detection of high-frequency currents with reduced coupling and parasitic loops.
Implementation Method 1
A magnetic field sensor for sensing a current through a conductor comprising a hole through the conductor in which the sensor is placed
Implementation Method 2
A magnetic field sensor configuration with sensing elements separated in directions perpendicular to the current, combined with magnetic concentrators
Implementation Method 3
external or stray magnetic fields can be compensated, without using large elements such as shields
Data Source
AI summary
A magnetic field sensor is provided for sensing a current flowing in a first direction divided in at least two conductor portions separated in a second direction perpendicular to the first direction. It includes at least a first sensing element and second sensing element and at least one integrated magnetic concentrator for sensing the magnetic field at respectively first and second positions in a region between the two conductor portions. The sensing elements are adapted in combination with the concentrator to sense the field with a highest sensitivity in a sensing direction perpendicular to the first direction, wherein the two positions are separated by a predetermined distance in a spacing direction perpendicular to the sensing direction.