Multi-Air-Gap Magnetoresistive Current Sensing for AC/DC Accuracy
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Solution Overview
Problem
Existing current sensors face challenges in accurately measuring high-frequency harmonics and high-current signals in complex environments due to poor anti-interference ability, conductor eccentricity errors, frequency response inconsistencies, and magnetic hysteresis effects, particularly in high-voltage and high-current applications.
Innovation Solution
A multi-air-gap magnetoresistance current sensor with a magnetoelectric conversion unit, signal processing unit, and feedback compensation unit, utilizing tunneling magnetoresistance elements and a multi-band feedback mechanism to achieve high sensitivity and accuracy, while minimizing interference and hysteresis effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If new magnetoresistance sensing technology is used to achieve high sensitivity, then measurement precision is improved, but anti-interference ability deteriorates
Solution Approach 1:
The patent divides the sensing system into multiple air-gaps (at least three) distributed around the conductor, with each air-gap containing a magnetoresistance element. This segmentation allows the system to average out local interference effects while maintaining high sensitivity, resolving the contradiction between measurement precision and anti-interference ability
Solution Approach 2:
The patent combines multiple magnetoresistance elements from different air-gaps into a unified sensing system that processes signals collectively. By merging the output signals from multiple elements positioned at different locations, the system achieves both high sensitivity (through magnetoresistance effect) and improved anti-interference capability (through spatial diversity and signal averaging)
2Measurement precision
If iron core is used in magnetoresistance sensor, then magnetic field gathering capability is improved, but magnetic hysteresis effect increases limiting linear range
Solution Approach 1:
The patent extracts the iron core from the sensing structure and replaces it with air-gaps, eliminating the source of magnetic hysteresis while preserving magnetic field gathering capability through the concentrated magnetic field effect at the air-gap interfaces. This allows the sensor to maintain high sensitivity without suffering from hysteresis-induced nonlinearity
Solution Approach 2:
The patent changes the magnetic circuit parameters by introducing multiple air-gaps with specific geometric configurations, transforming the magnetic field distribution to achieve both strong field concentration (for high sensitivity) and linear B-H characteristics (by operating in the air-dominated regime rather than iron-dominated regime, eliminating hysteresis effects)
3Device complexity
If single-air-gap structure is used, then device complexity is reduced, but conductor eccentricity error increases
Solution Approach 1:
The patent segments the single air-gap into multiple air-gaps distributed around the conductor, creating a multi-element sensing array. This segmentation provides spatial redundancy that compensates for conductor position variations, reducing eccentricity errors while maintaining relatively simple device structure
Solution Approach 2:
The patent strategically positions the multiple air-gaps asymmetrically or symmetrically around the conductor based on specific measurement requirements, optimizing the sensing geometry to minimize eccentricity effects. The asymmetric distribution of air-gaps allows the system to maintain high measurement precision even when the conductor is not perfectly centered
4Measurement precision
If existing current sensors are used for high-frequency harmonics measurement, then measurement capability is limited, but insulation performance is poor
Solution Approach 1:
The patent replaces traditional electromagnetic induction-based current transformers with a magnetoresistance-based sensing system that uses tunneling magnetoresistance (TMR) or giant magnetoresistance (GMR) effects. This substitution enables high-frequency response capability while maintaining excellent insulation performance, as the sensing elements are electrically isolated from the high-voltage conductor
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 high accuracy and wide frequency domain consideration for AC/DC current measurements, enhancing the performance of high-voltage and high-current measurement equipment.
Implementation Method 1
N new magnetoresistance elements connected in parallel, N air-gap openings are symmetrically arranged on the iron core, and the N new magnetoresistance elements are respectively located at centers of the N air-gap openings
Implementation Method 2
adjust a feedback current based on the amplified voltage signal output by the signal processing unit to enable the new magnetoresistance elements to operate at zero magnetic flux
Data Source
Figure 1~2
AI summary
The disclosure relates to a multi-air-gap magnetoresistance current sensor for alternating current-direct current and a current measurement method, and the multi-air-gap magnetoresistance current sensor for alternating current-direct current includes: a magnetoelectric conversion unit, configured to obtain a magnetic field signal of a target current-carrying wire with to-be-measured current, convert the magnetic field signal into an electric signal, and output the electric signal to a signal processing unit, the magnetoelectric conversion unit adopts a multi-air-gap multi-band closed-loop iron core type structure; a signal processing unit, configured to amplify the electric signal and output the electric signal to a feedback compensation unit; and the feedback compensation unit, configured to adjust a feedback current according to the amplified voltage signal to enable the new magnetoresistance elements to operate at zero magnetic flux, measure a feedback current value, and obtain and output a value of to-be-measured current according to the feedback current value. According to the multi-air-gap magnetoresistance current sensor for alternating current-direct current and the current measurement method provided by the embodiments of the invention, the measurement performance of the current sensor is improved, and the problem of high accuracy and wide frequency domain consideration of current measurement for alternating current-direct current is solved.