Magnetic Current Sensor Layout for Compact, Accurate Bus Bars
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Solution Overview
Problem
Existing electric current sensor devices face challenges in reducing size while maintaining detection accuracy due to heat generation and magnetic interference between bus bars, leading to increased package size and decreased accuracy when bus bars are arranged closely together.
Innovation Solution
The device employs a configuration where magnetic detection elements are arranged in a stacking direction along narrow portions of conductors, with specific width ratios and recessed slits to minimize heat and interference, allowing for reduced spacing between conductors while maintaining accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the distance between slits is reduced to minimize heat generation, then heat generation is reduced, but the interval between magnetic detection elements cannot be reduced, causing the package size to increase
Solution Approach 1:
The patent transitions from a planar arrangement of magnetic detection elements to a three-dimensional stacked configuration. Multiple magnetic detection elements are arranged in the thickness direction (z-direction) of the bus bar, allowing them to be positioned closer together without increasing the lateral footprint. This vertical stacking enables reduced package size while maintaining adequate spacing to manage heat generation.
2Productivity
If multiple bus bars are arranged at predetermined intervals, then current detection can be performed, but magnetic flux from adjacent bus bars affects detection accuracy
Solution Approach 1:
The patent introduces a non-magnetic material as an intermediary substance between adjacent bus bars and magnetic detection elements. This non-magnetic material acts as a magnetic shield, blocking magnetic flux from adjacent bus bars from reaching the detection elements. This enables bus bars to be arranged closer together while maintaining detection accuracy by preventing magnetic interference.
3Volume of stationary object
If the interval between bus bars is reduced to downsize the device, then device size is reduced, but magnetic flux interference from adjacent bus bars increases
Solution Approach 1:
The non-magnetic material serves as a magnetic barrier that isolates magnetic detection elements from magnetic flux generated by adjacent bus bars. This allows the bus bars to be positioned closer together, reducing the overall device volume, while the non-magnetic material prevents magnetic interference that would otherwise increase with closer spacing.
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 downsizing of the electric current sensor device while ensuring high detection accuracy and reducing heat generation, suitable for applications in vehicles with three-phase AC motors.
Implementation Method 1
a first detector including a first magnetic detection element and a second magnetic detection element that detect magnetism generated by a current flowing through the first conductor
Data Source
AI summary
An electric current sensor device includes a first detector including first and second magnetic detection elements that detect magnetism generated by a current flowing through a first conductor, the first detector detecting a current of the first conductor based on results of the elements, and a second detector including third and fourth detection elements that detect magnetism generated by the second conductor, the second detector detecting a current of the second conductor based on results of the third and fourth elements. The first conductor includes a first wide portion with a first width through which a current flows in a first direction, and a first narrow portion through which a current flows in a second direction, whose width is a second width narrower than the first, and the first and second elements are arranged in a stacking direction of the first narrow portion, and side by side along the surface.