Ring Concentrator Current Sensor Minimizing Air Gap
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Solution Overview
Problem
Existing current measurement devices are inefficient and costly due to large air gaps in yokes, requiring excessive ferromagnetic material and high production costs, especially when measuring both small standby currents and high load currents.
Innovation Solution
A current measurement device with a ring concentrator made of thin ferromagnetic material and a magnetic field sensor that minimizes the effective air gap, using a magnetic circuit with a semiconductor chip and a shield to enhance sensitivity and reduce material usage, allowing for continuous measurement of up to 100 A and brief measurement of up to 1000 A.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large air gap (1-3 mm) is used in the yoke, then the device can measure both small standby currents and large load currents, but the yoke requires a lot of ferromagnetic material and production becomes expensive
Solution Approach 1:
The patent changes the air gap parameter from 1-3 mm to a minimal air gap of only a few micrometers. This parameter change allows the magnetic circuit to become highly efficient, enabling measurement of both small standby currents (10-100 mA) and large load currents (up to 1000 A) without requiring excessive ferromagnetic material. The minimal air gap reduces magnetic reluctance while maintaining the ability to handle the full current range.
Solution Approach 2:
The patent extracts the magnetic circuit design from conventional yoke structures with large air gaps and implements a planar magnetic circuit with minimal air gap. This extraction of the essential function (magnetic flux concentration) from the bulky yoke structure eliminates the need for excessive ferromagnetic material while preserving current measurement capability across the full range.
2Adaptability or versatility
If a large air gap (1-3 mm) is used in the yoke, then the device can measure both small standby currents and large load currents, but production becomes expensive
Solution Approach 1:
The patent replaces the conventional mechanical yoke structure with large air gap with a planar magnetic circuit implementation. This substitution uses thin ferromagnetic layers (1-10 μm) deposited on a substrate, eliminating the need for bulky three-dimensional yoke assembly. The planar structure is manufactured using thin-film deposition techniques, which are more cost-effective and suitable for mass production compared to traditional yoke fabrication.
Solution Approach 2:
The patent employs thin ferromagnetic films (1-10 μm thickness) instead of thick yoke structures. These thin films are deposited using physical vapor deposition (PVD) or chemical vapor deposition (CVD) methods, creating a flexible, planar magnetic circuit that is both material-efficient and cost-effective to manufacture at scale.
3Reliability
If conventional current sensors with large air gaps are used, then they can handle high currents, but they require excessive material and have high production costs
Solution Approach 1:
The patent fundamentally changes the air gap parameter from millimeter scale (1-3 mm) to micrometer scale (a few μm). This parameter change dramatically reduces magnetic reluctance in the magnetic circuit, enabling reliable measurement of high currents (up to 1000 A) while using minimal ferromagnetic material. The minimal air gap ensures efficient magnetic flux transfer without requiring bulky yoke structures.
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 device achieves high sensitivity and reduced material costs by minimizing the effective air gap and using planar technology, enabling efficient measurement across a wide range of currents with lower magnetic resistance and smaller calibration currents.
Implementation Method 1
The ring concentrator 2 and the magnetic field sensor 4 completely enclose the conductor 1 and together form a magnetic circuit. The ring concentrator 2 extends in a substantially perpendicular to the conductor 1 level... The magnetic field sensor 4 is arranged below or above the air gap 3 ring concentrator 2 and is used to measure the magnetic field that is generated by the current I flowing through the conductor 1 in the area of the air gap 3.
Implementation Method 2
The magnetic field sensor 4 is arranged below or above the air gap 3 ring concentrator 2 and is used to measure the magnetic field that is generated by the current I flowing through the conductor 1 in the area of the air gap 3.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The device has a circular concentrator (2) made of ferromagnetic material and extending in a plane running perpendicular to a current conductor (1). A magnetic field sensor (4) has a magnetic element (10) i.e. magneto resistive sensor and flux gate sensor, attached to a semiconductor chip and arranged above or below an air gap (3) of the concentrator for bridging the air gap. Two end areas of the magnetic element and two end areas of the concentrator overlap with each other, respectively, and a shield (5) partially surrounds the concentrator in the plane that is clamped by the concentrator.