Soft Magnetic Body Current Sensor for Balancing Power and Accuracy
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Solution Overview
Problem
Magnetic balance type current sensors face a trade-off between current detection accuracy and power consumption, where either sensitivity is compromised or power consumption is high due to existing designs that either attenuate the signal magnetic field too much or amplify it excessively.
Innovation Solution
A current sensor design incorporating a magneto-resistive effect element, a feedback coil, a first soft magnetic body between the element and the current line, and a pair of second soft magnetic bodies on both sides of the element to attenuate and intensify the signal and cancelling magnetic fields respectively, optimizing both sensitivity and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a magnetic shield is provided between the magneto-resistive effect element and the current line to attenuate the signal magnetic field, then power consumption is reduced, but detection accuracy deteriorates due to decreased sensitivity
Solution Approach 1:
The magnetic shield is divided into multiple segments: a first magnetic shield portion positioned between the current line and the magneto-resistive effect element to attenuate the signal magnetic field, and second magnetic shield portions positioned on both sides of the magneto-resistive effect element to intensify the magnetic field. This segmentation allows different regions to perform different functions, resolving the contradiction between power reduction and sensitivity maintenance.
Solution Approach 2:
Different portions of the magnetic shield are designed with different properties and positions. The first magnetic shield portion (between current line and element) has attenuation function, while the second magnetic shield portions (on sides of element) have intensification function. This local differentiation allows simultaneous achievement of power consumption reduction and detection accuracy maintenance.
2Measurement precision
If magnetic cores are provided on both sides of the magneto-resistive effect element to intensify the signal magnetic field, then sensitivity is improved, but power consumption increases due to increased feedback current
Solution Approach 1:
The magnetic shielding structure is segmented into a first portion for attenuation and second portions for intensification. The second magnetic shield portions on both sides of the magneto-resistive effect element intensify both the signal magnetic field and the cancelling magnetic field, thereby improving sensitivity while the first magnetic shield portion maintains power consumption at acceptable levels by attenuating excessive signal field.
Solution Approach 2:
The magnetic shield portions are designed with specific geometric parameters (widths, positions, thicknesses) that optimize the balance between field intensification and power consumption. By adjusting these parameters, the system achieves improved sensitivity without proportional increase in power consumption.
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 design achieves high current detection accuracy while limiting power consumption by effectively managing the signal and cancelling magnetic fields, preventing excessive attenuation or amplification, thus balancing sensitivity and power efficiency.
Implementation Method 1
a magneto-resistive effect element which is arranged near a current line, to which a signal magnetic field (first magnetic field) is applied, the signal magnetic field being induced by a current that flows in the current line, and which generates a magneto-resistive change in accordance with a change of the signal magnetic field
Implementation Method 2
The voltage signal is inputted into the feedback coil, and the feedback coil generates a cancelling magnetic field that cancels the signal magnetic field
Implementation Method 3
a first soft magnetic body that is provided between the magneto-resistive effect element and the current line
Implementation Method 4
a pair of second soft magnetic bodies that are provided on both sides of the magneto-resistive effect element with regard to a magnetization detecting direction of the magneto-resistive effect element
Data Source
AI summary
A current sensor has: a magneto-resistive effect element which is arranged near a current line, to which a signal magnetic field is applied, the signal magnetic field being is induced by a current that flows in the current line, and which generates a magneto-resistive change in accordance with a change of the signal magnetic field; cancelling magnetic field generating means that is provided near the magneto-resistive effect element and that generates a cancelling magnetic field that cancels the signal magnetic field; a first soft magnetic body that is provided between the magneto-resistive effect element and the current line; and a pair of second soft magnetic bodies that are provided on both sides of the magneto-resistive effect element with regard to a magnetization detecting direction of the magneto-resistive effect element.