Current Sensor Asymmetric Magnetic Detection for Displacement Error
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Solution Overview
Problem
Current sensors used in electric vehicles and hybrid cars face a significant reduction in measurement accuracy due to displacement of the current path, which is often caused by installation errors or vibrations, leading to inaccuracies in current measurement.
Innovation Solution
A current sensor design featuring a pair of magnetic detection elements disposed symmetrically on opposite sides of a virtual line passing through the gravity center of the current path, with sensitivity axes perpendicular to the current direction, allowing for cancellation of output errors resulting from path displacement through differential processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two magnetic detection elements are disposed symmetrically in a substrate to measure current, then current measurement capability is achieved, but measurement precision deteriorates when the current path position is displaced
Solution Approach 1:
The patent applies asymmetry by disposing the two magnetic detection elements at different distances from the current path. Specifically, the first magnetic detection element is positioned closer to the current path than the second magnetic detection element. This asymmetric arrangement creates differential sensitivity to magnetic field changes, allowing the system to compensate for position displacement errors through arithmetic processing of the two detection values, thereby maintaining measurement precision even when the current path position varies.
2Ease of operation
If the current path is installed in a concave portion of the substrate, then ease of installation is improved, but manufacturing precision deteriorates due to installation errors and vibrations
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-positioning the two magnetic detection elements at specific asymmetric locations relative to the expected current path position before the actual current path installation. This preliminary arrangement ensures that even if the current path is later displaced due to installation errors or vibrations in the concave portion, the detection elements are already optimally positioned to detect and compensate for such displacements through their asymmetric configuration.
3Measurement precision
If magnetic detection elements are placed close to the current path for accurate detection, then measurement capability is improved, but sensitivity to position displacement increases
Solution Approach 1:
The patent applies segmentation by dividing the single detection function into two separate magnetic detection elements positioned at different locations. The first detection element is placed closer to the current path while the second is placed farther away. This segmentation allows each element to have different sensitivity characteristics, and through arithmetic processing of their combined outputs, the system achieves both high detection sensitivity and reduced sensitivity to position displacement errors.
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 effectively suppresses the decrease in current measurement accuracy by reversing the pluses and minuses of output errors, maintaining precision even when the current path is displaced, thereby ensuring reliable current measurement in dynamic environments.
Implementation Method 1
a type of current sensor detecting the change of a magnetic field occurring from a current conducted through a current path, using a magnetic detection element
Data Source
AI summary
A current sensor of the present invention includes a mounting unit including a disposition region in which a current path is disposed, a pair of magnetic detection elements disposed in the mounting unit so as to sandwich therebetween the disposition region, and an arithmetic circuit performing an arithmetic operation on the current value of the current path on the basis of the detection values of the pair of magnetic detection elements. The pair of magnetic detection elements is disposed on sides opposite to each other with respect to a virtual line passing through the gravity center of the current path in cross-sectional view of the current path, and individually has sensitivity axes parallel to a direction perpendicular to the direction of a current conducted through the current path and the direction of the virtual line.