Current Sensor Asymmetric Bus Bar Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current sensors measuring current through bus bars with rectangular cutouts near corners suffer from increased noise due to adjacent bus bar magnetic fields, reducing the signal-to-noise ratio, especially in compact designs required for vehicles.
Innovation Solution
The magneto-electric conversion elements are positioned lower than their counterparts on a substrate, with their sensitive axes orthogonal to adjacent bus bars, and mounted on opposite surfaces to minimize magnetic field influence, allowing adjustment of magnetic field alignment with the current center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the cutout portion and magneto-electric conversion element are disposed in the vicinity of the corner of the bus bar to achieve compact design, then the size of the current sensor is reduced, but the noise from adjacent bus bar magnetic field increases and the signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies asymmetry by making the first extending portion of the first bus bar have a different length than the second extending portion of the second bus bar. Specifically, the first extending portion is set to be shorter than the second extending portion, creating an asymmetric configuration that positions the magneto-electric conversion element away from the strongest magnetic field regions of adjacent bus bars, thereby reducing noise while maintaining compact size
Solution Approach 2:
The patent utilizes the vertical dimension (height direction) to solve the problem. By adjusting the vertical position of the magneto-electric conversion element and creating asymmetric extending portions at different heights, the patent positions the sensor in a spatial location that minimizes exposure to magnetic field noise from adjacent bus bars while maintaining compact overall dimensions
2Measurement precision
If the magneto-electric conversion element is positioned at the center of the current through the adjacent bus bar, then the measurement accuracy is improved, but the influence of magnetic field noise from the adjacent bus bar increases
Solution Approach 1:
The patent applies local quality by creating different configurations for different parts of the bus bar structure. The first bus bar has a shorter first extending portion while the second bus bar has a longer second extending portion, creating localized structural differences that optimize the magnetic field environment at the specific location of the magneto-electric conversion element, thereby reducing noise while maintaining measurement accuracy
Solution Approach 2:
The patent converts the harmful magnetic field from the adjacent bus bar into a beneficial configuration by strategically positioning the magneto-electric conversion element. By making the first extending portion shorter and the second extending portion longer, the patent creates a magnetic field distribution where the conversion element is positioned in a region with reduced noise interference, effectively using the adjacent bus bar's magnetic field structure to the advantage of noise reduction
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 reduces the impact of adjacent bus bar magnetic fields on the current sensor, improving the signal-to-noise ratio even when cutouts are near bus bar corners, facilitating size reduction and noise reduction.
Implementation Method 1
a magnetic field generating unit that generates a magnetic field in accordance with a current value to be measured
Implementation Method 2
magneto-electric conversion elements are disposed in the cutout portion to measure the current flowing through the bus bars
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3
AI summary
A current sensor 1 capable of reducing the influence of a magnetic field from an adjacent bus bar even when a cutout portion and a magneto-electric conversion element are disposed in the vicinity of a corner of the bus bar includes a substrate 2, a first bus bar 10, and a second bus bar 20. The first bus bar 10 includes a first terminal portion 11, a first rising portion 12, a first extending portion 14, a first cutout portion 15, and a first stepped portion 17. The second bus bar 20 includes a second terminal portion 21, a second rising portion 22, a second extending portion 24, a second cutout portion 25, and a second stepped portion 27. The second stepped portion 27 and the second rising portion 22 are connected together. A second magneto-electric conversion element 28 is mounted on the lower surface of the substrate 2. A first magneto-electric conversion elements 18 is mounted on the upper surface of the substrate 2.