Asymmetric Shielded Current Sensor for High-Accuracy Large Current Detection
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Solution Overview
Problem
High-sensitivity magnetic sensing elements like GMR sensors can only detect a narrow range of magnetic field intensities, making it difficult to accurately measure large currents, such as those in three-phase motors, as the generated magnetic field exceeds their detection capabilities.
Innovation Solution
A current sensor design featuring a busbar with a through-hole and current paths on both sides, sandwiched by asymmetrically arranged magnetic shield plates, with the magnetic sensing element positioned to overlap the through-hole, reducing the detected magnetic field intensity and allowing for high-accuracy detection of large currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-sensitivity magnetic sensing element such as a GMR sensor is used, then measurement precision is improved, but the device can only detect a narrow range of magnetic field intensity, making it unable to accurately measure large currents
Solution Approach 1:
The patent introduces magnetic shield plates as intermediary elements between the busbar and the magnetic sensing element. These shield plates selectively attenuate the magnetic field generated by the busbar before it reaches the sensing element, allowing the high-sensitivity GMR sensor to detect large currents by reducing the field intensity to its detectable range while maintaining measurement accuracy
Solution Approach 2:
The patent changes the magnetic field intensity parameter by using magnetic shield plates with specific permeability characteristics. The shield plates modify the magnetic field distribution and intensity, transforming a field that is too strong for the GMR sensor into one that falls within the sensor's optimal detection range, thereby enabling accurate measurement of large currents
2Stability of the object's composition
If the busbar is positioned at the center between shield plates, then structural symmetry is achieved, but the magnetic field intensity at the sensing element remains too large for accurate detection
Solution Approach 1:
The patent deliberately introduces asymmetry in the positioning of the busbar relative to the shield plates. By offsetting the busbar from the central position, the magnetic field distribution becomes asymmetric, creating a region where the field intensity is reduced to a level suitable for the GMR sensor's detection range while maintaining sufficient field strength for accurate measurement
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
This configuration enables the use of high-sensitivity magnetic sensing elements like GMR sensors to accurately detect large currents by attenuating the magnetic field, effectively extending their detection range and improving measurement accuracy.
Implementation Method 1
a magnetic sensing element for detecting intensity of a magnetic field generated by the current flowing through the busbar
Implementation Method 2
a pair of shield plates that comprise a magnetic material and are arranged to sandwich the busbar in a thickness direction of the busbar
Data Source
AI summary
A current sensor includes a busbar carrying an electric current to be measured, a magnetic sensing element for detecting intensity of a magnetic field generated by the current flowing through the busbar, and a pair of shield plates that include a magnetic material and are arranged to sandwich the busbar in a thickness direction of the busbar. The busbar includes a through-hole penetrating therethrough and current paths formed on both sides of the through-hole, the magnetic sensing element is arranged at a position overlapping the through-hole in the thickness direction of the busbar. The busbar is arranged in a space between the pair of shield plates such that the center in the thickness direction is located at a position offset from the center of the space in the thickness direction.