Rogowski Current Sensor PCB Coil Constant Turn Density
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Solution Overview
Problem
Current Rogowski coils for measuring alternating currents have low measurement sensitivity and poor immunity to external magnetic fields due to irregular winding and size constraints, making them unsuitable for industrial applications with closely spaced primary conductors.
Innovation Solution
A Rogowski-type current sensor with a substantially polygonal electric coil design featuring regular pitch and turn density across both rectilinear and circular sectors, optimized with additional turns of varying widths to maintain constant turn density and minimize sensitivity variations, allowing for improved measurement precision and immunity to external fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional winding techniques are used to produce Rogowski coils, then good quality coils with constant linear density of turns can be obtained, but the production process becomes very complex, costly and difficult to reproduce
Solution Approach 1:
The patent replaces conventional mechanical winding techniques with printed circuit board (PCB) technology to manufacture Rogowski coils. The coil windings are created as conductive traces on a PCB substrate, eliminating the need for complex mechanical winding equipment and manual assembly processes. This substitution maintains manufacturing precision through standardized PCB fabrication while dramatically simplifying the production process and enabling industrial reproducibility.
Solution Approach 2:
The patent changes the manufacturing approach from mechanical winding parameters (thread tension, winding speed, manual positioning) to PCB fabrication parameters (trace width, copper thickness, etching precision). This parameter transformation allows the same functional requirements to be met through a different technological domain with inherently better repeatability and lower complexity.
2Manufacturing precision
If Rogowski coils are made in the form of a printed circuit, then high precision of the winding layout and industrial reproducibility are obtained, but the measurement sensitivity becomes low due to low density of turns
Solution Approach 1:
The patent transitions from two-dimensional planar PCB traces to three-dimensional立体 windings by adding vertical height through multiple layers and overlapping structures. The coil windings extend in the Z-direction (perpendicular to the PCB surface), creating a volumetric sensing region that increases turn density and measurement sensitivity while preserving the PCB manufacturing advantages.
Solution Approach 2:
The patent combines PCB trace material (copper on fiberglass substrate) with additional conductive materials and structural elements to create a composite coil structure. This composite approach allows the integration of high-density winding regions with the rigid, precision-manufacturable PCB base, achieving both manufacturing precision and enhanced measurement sensitivity.
3Object-affected harmful factors
If circular Rogowski coils are used, then good immunity to external magnetic fields is obtained, but the size of the current sensor becomes much larger than with rectangular coils
Solution Approach 1:
The patent applies curved geometries to the rectangular coil structure by rounding the corners and adding circular arc sections to the PCB trace layout. These curved elements provide the magnetic field immunity benefits associated with circular coils while maintaining the overall compact rectangular footprint suitable for close-spaced conductor applications.
4Measurement precision
If the density of turns in rectilinear sections is increased to improve measurement sensitivity, then the pitch between turns must be reduced, but this creates irregularities in the winding that affect immunity to external magnetic fields
Solution Approach 1:
The patent applies different turn densities to different regions of the coil: high-density winding sections are placed in the rectilinear portions where they contribute to measurement sensitivity, while the circular arc sections maintain uniform, lower density for magnetic field immunity. This local differentiation allows each region to optimize its function without compromising the other.
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 enhances measurement sensitivity and immunity to primary conductor position and external fields, enabling compact installation and integration in various configurations, comparable to circular coil technologies.
Implementation Method 1
an electric coil produced in the form of a printed circuit... an electronic unit for conditioning the signal of said electric coil
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Current sensor for measuring an alternating current. The invention relates to a current sensor provided with an electric coil (5) made in the form of a printed circuit. Its closed contour is inscribed within a rectangle delimiting a through window (9) for passing a primary conductor (2). It comprises four rectilinear segments (TR), linked in pairs by a circular sector (SC), delimited by an interior arc (10) and an exterior arc (11). It comprises, in its circular sectors (SC), additional turns (13), which extend from the exterior arc (11) to an intermediate arc (14) disposed between the interior arc (10) and the exterior arc (11). They are interposed between the main turns (12) in such a way that the spacing between two consecutive turns (12, 13) on the exterior arc (11) is equal to the spacing P of the main turns (12) in the rectilinear segments (TR) and that the mean density of turns is almost constant in the electric coil (5).