Magnetic Field Sensor Device for Current Measurement
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Solution Overview
Problem
Existing magnetic field sensor devices for current measurement face challenges such as non-linearity in magnetic field changes, limited bandwidth, and measurement inaccuracies due to the use of ferrite rings and multiple MR sensors, which require additional effort for signal processing and are prone to measurement errors from external interference.
Innovation Solution
A magnetic field sensor device with a ring-shaped arrangement of permanent magnetic elements generating an auxiliary magnetic field tangential or parallel to the magnetic field sensor elements, which adjusts sensitivity and shields external interference, eliminating the need for current-carrying coils and improving homogeneity and shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If ferrite ring is used to guide magnetic field, then magnetic field guidance is improved, but linearity is lost and bandwidth is limited
Solution Approach 1:
The invention removes the ferrite ring from the magnetic field sensor device, extracting the problematic magnetic field guidance component that caused non-linearity and bandwidth limitations. The patent explicitly states that the ferrite ring leads to saturation and non-linearity, so its removal resolves the contradiction by eliminating the source of measurement errors while maintaining magnetic field detection capability through alternative means.
Solution Approach 2:
The invention uses multiple magnetoresistive sensors arranged around the conductor to copy the magnetic field measurement at different positions. This array of sensors replaces the single-point measurement that would require ferrite guidance, allowing accurate current determination through spatial sampling without the need for magnetic field concentrating structures that cause non-linearity.
2Measurement precision
If multiple MR sensors are arranged around conductor, then measurement accuracy is improved, but device complexity and signal processing effort increase
Solution Approach 1:
The invention divides the measurement task into multiple independent magnetoresistive sensors positioned at different angular positions around the conductor. Each sensor provides a separate measurement that can be individually processed, and the final current value is obtained by combining these segmented measurements. This segmentation approach improves accuracy through spatial sampling while maintaining manageable device complexity through modular sensor units.
Solution Approach 2:
The invention combines the outputs of multiple magnetoresistive sensors to determine the total current. By merging the measurement data from sensors positioned at different locations and orientations, the system achieves more accurate current measurement than a single sensor could provide, while the combination process is simplified through established signal processing techniques for multi-sensor arrays.
3Measurement precision
If auxiliary magnetic field is applied to magnetoresistive sensor, then sensitivity is improved, but external interference shielding is reduced
Solution Approach 1:
The invention applies different magnetic field conditions to different sensors in the array. Each magnetoresistive sensor receives a tailored auxiliary magnetic field configuration optimized for its specific position and measurement function. This local optimization allows each sensor to achieve high sensitivity for its particular measurement task while the overall array maintains resistance to external interference through diverse sensing orientations and positions.
Solution Approach 2:
The invention uses feedback in the signal processing to compensate for external magnetic field interference. By continuously monitoring the outputs of multiple sensors and analyzing patterns consistent with external interference versus actual current measurements, the system can identify and subtract interference components, maintaining both sensitivity to current and resistance to external magnetic fields through active compensation.
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 solution provides a universally usable, accurate, and cost-effective magnetic field sensor device with enhanced measurement accuracy and reduced interference, capable of precise current measurement across various ranges without linearity errors or temperature-dependent drifts.
Implementation Method 1
magnetoresistive resistors based on an AMR, GMR, TMR or XMR effect
Implementation Method 2
magnetoresistive resistors based on an AMR, GMR, TMR or XMR effect
Implementation Method 3
magnetoresistive resistors based on an AMR, GMR, TMR or XMR effect
Implementation Method 4
magnetoresistive resistors based on an AMR, GMR, TMR or XMR effect
Implementation Method 5
a magnetic field generating device, which has permanent magnetic magnet elements following the course of the curve, which generate an auxiliary magnetic field at the location of the magnetic field sensor elements
Implementation Method 6
They detect a magnetic field strength surrounding a conductor or a plurality of conductors H along a closed curve S, giving a conclusion about the total current I, passing through the area A passing through the curve S is bounded, according to Ampère's law
Data Source
Figure 1~2
Figure 3a~3c
Figure 4~5
AI summary
The invention relates to a magnetic field sensor device (10, 66, 100, 102, 104, 106, 108, 114, 116, 118) for measuring the current of at least one current-carrying conductor (12), comprising a plurality of magnetic field sensor elements (14) which are arranged around the conductor (12) along a closed curve (16), preferably a circular, rectangular, or elliptical curve, and which have a preferred magnetic field-sensitivity direction substantially tangential or parallel to the curve (16). The magnetic field sensor device also comprises a magnetic field generating device (20). The magnetic field generating device (20) comprises at least one magnet element (24), preferably multiple permanently magnetic abutting magnet elements which follow the course of the curve, said magnet element(s) generating an auxiliary magnetic field (22) at the location of the magnetic field sensor elements (14), wherein the auxiliary magnetic field is oriented substantially at a right angle to the course of the curve (16) of the magnetic field sensor element (14). A secondary aspect relates to a current clamp (60) which comprises the aforementioned magnetic field sensor device (10, 66, 100, 102, 104, 106, 108, 10, 112, 114, 116, 118).