U-Shaped Current Sensor Shielding for Magnetic Interference Rejection
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Solution Overview
Problem
Existing current sensor units face challenges in effectively suppressing external magnetic interference fields while maintaining high sensitivity and isotropic shielding, leading to anisotropic effects and reduced sensitivity due to the orientation of interfering fields.
Innovation Solution
A current sensor unit design featuring a U-shaped shield with a magnetic field sensor positioned between two parallel side walls and a rear wall, where the conductor is partially enclosed, allowing the sensor to be placed in an area of maximum shielding effectiveness, thereby enhancing isotropic shielding and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a U-shaped shield with near-complete enclosure is used to suppress external magnetic fields, then shielding effectiveness is improved, but the magnetic field is also concentrated within the shield and routed past the sensor, reducing sensitivity
Solution Approach 1:
The shield is designed as a U-shaped structure with two separate parallel side walls and an open front, segmenting the shielding function to block magnetic fields from specific directions (top, bottom, rear) while leaving the front open to allow the magnetic field to reach the sensor. This segmentation resolves the contradiction by providing directional shielding without complete enclosure.
Solution Approach 2:
The shield provides localized shielding effectiveness at specific locations (top, bottom, and rear of the sensor) rather than uniform shielding in all directions. The open front configuration allows the magnetic field to pass through to the sensor while the shielded regions block external interference, creating local quality differences in field distribution that resolve the sensitivity-shielding contradiction.
2Object-affected harmful factors
If two U-shaped shielding devices are used to achieve sufficiently isotropic shielding effect, then shielding isotropy is improved, but device complexity and material usage increase
Solution Approach 1:
The single U-shaped shield performs multiple functions: it provides magnetic shielding from three directions (top, bottom, rear) simultaneously, defines the sensor positioning space, and guides the magnetic field to the sensor. This multi-functionality replaces the need for two separate shields, reducing complexity while maintaining isotropic shielding effectiveness.
Solution Approach 2:
The shield extends in the vertical dimension with two parallel side walls connected by a rear wall, creating a three-dimensional shielding structure that blocks magnetic fields from multiple directions simultaneously. This dimensional approach achieves isotropic shielding with a single component rather than requiring multiple planar shields.
3Measurement precision
If the magnetic field sensor is positioned close to the current conductor to maintain sensitivity, then measurement precision is improved, but the sensor is more susceptible to external magnetic interference
Solution Approach 1:
The U-shaped shield acts as an intermediary structure between the external environment and the sensor-conductor system. It selectively blocks external magnetic fields from reaching the sensor while allowing the desired magnetic field from the current conductor to pass through to the sensor, thus protecting the close-positioned sensor from interference.
Solution Approach 2:
The shield creates a localized protected zone around the sensor and conductor, providing magnetic field shielding specifically where needed (at the sensor location) without affecting the overall system configuration or requiring the sensor to be positioned farther away from the conductor.
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 shielding effectiveness against external magnetic interference, maintaining sensor sensitivity and reducing material and cost, while minimizing coupling of external fields into the useful signal.
Implementation Method 1
measuring the magnetic flux density generated by the current
Implementation Method 2
a U-shaped shield with two parallel side walls and a rear wall connecting the two side walls
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a current sensor unit (10), comprising - an at least partially flat electrical conductor (12), a magnetic field sensor (14) measuring a first magnetic field component and a U-shaped shield (16) with two side walls (16.1) running in parallel and a rear wall (16.2) connecting the two side walls, wherein the magnetic field sensor is arranged along a centre surface between the two side walls running at the same distance from each of the two side walls and perpendicular to the rear wall and the electrical conductor is arranged at least partially between one of the two side walls and the magnetic field sensor.