Dual-Ring TMR Current Sensor for Crosstalk and Eccentricity Errors
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Solution Overview
Problem
Conventional iron-core current sensors suffer from poor linearity and temperature stability, leading to measurement inaccuracies and unsuitability for wide-range applications, while annular magnetic sensor arrays face issues with precision due to crosstalk noise and eccentricity errors.
Innovation Solution
An iron core annular array multi-ring magnetosensitive current sensor is designed with a first ring structure featuring an open iron core and TMR sensing chips, and a second ring structure with multiple TMR chips, utilizing a digital processing unit to combine magnetic field signals and correct errors through compensating magnetic fields and digital signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional iron-core current sensor is used, then the structure is simple and cost-effective, but the measurement precision deteriorates due to poor linearity and temperature stability
Solution Approach 1:
The sensor divides the measurement function into two separate ring structures: the first ring structure with iron core handles flux concentration and feedback, while the second ring structure with TMR sensors performs precise measurement. This segmentation allows each component to optimize its specific function, resolving the contradiction between structural simplicity and measurement precision.
Solution Approach 2:
The patent introduces a compensating winding as an intermediary element that generates a compensating magnetic field to counteract the influence of the measured current on the first ring structure. This intermediary mechanism enables the iron core to maintain flux concentration benefits while eliminating its negative impact on measurement accuracy.
2Reliability
If an annular magnetic sensor array without iron core is used, then transient performance is improved and saturation problem is eliminated, but measurement precision deteriorates due to crosstalk noise and eccentricity errors
Solution Approach 1:
The sensor separates the flux concentration function (first ring with iron core) from the measurement function (second ring with TMR sensors). This segmentation allows the iron core to enhance transient response without introducing saturation, while the dedicated measurement ring maintains precision by using multiple TMR sensors arranged to minimize crosstalk and eccentricity effects.
Solution Approach 2:
The patent merges the advantages of iron-core structures (flux concentration, transient response) with the advantages of annular arrays (no saturation, contactless measurement) into a unified dual-ring system. The first ring provides magnetic flux guidance while the second ring performs accurate measurement, combining benefits from both conventional and modern approaches.
3Ease of operation
If multiple TMR sensors are arranged in an annular array, then contactless measurement capability is achieved, but crosstalk noise increases and reduces measurement precision
Solution Approach 1:
The patent extracts the measurement sensors from direct contact with the current-carrying conductor, arranging them in an annular array around the conductor. This spatial extraction enables contactless measurement while the specific geometric arrangement and use of compensating fields minimizes crosstalk between adjacent sensors, maintaining measurement precision.
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 effectively reduces eccentricity and crosstalk errors, enhancing precision and expanding application scope for accurate current measurement in power systems.
Implementation Method 1
A first tunnel magnetoresistance (TMR) sensing chip is provided at each of the two air gaps, and is configured to measure the first magnetic field signal
Implementation Method 2
The compensating winding is wound evenly around the iron core, and configured to generate a compensating magnetic field according to the feedback current signal, superpose the compensating magnetic field and the first magnetic field signal
Implementation Method 3
a basic principle of the contactless current measurement is to measure a magnetic field based on Ampere current circuit law using multiple TMR sensors surrounding a current-carrying conductor
Data Source
Figure 1~2
Figure 3~4
AI summary
An iron core-annular array multi-ring magnetosensitive current sensor and a current measurement method, the method comprising: using a first loop structure (101) to acquire a feedback current signal generated according to a first magnetic field signal generated by a primary side current; using a second loop structure (102) to measure a second magnetic field signal generated by the current of a wire in a coil; and using a digital processing unit (103) to calculate, according to the feedback current signal and the second magnetic field signal, the feature quantity that characterizes the current of the wire, and determining the current on the wire according to the feature quantity that characterizes the current of the wire.