Asymmetric Segmented Rogowski Coil for Current Sensing
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Solution Overview
Problem
Current sensing devices, particularly Rogowski coils, face challenges in achieving accuracy, repeatability, and cost efficiency due to complex winding configurations, lack of flexibility, and high manufacturing costs, making them unsuitable for versatile applications, especially in three-phase systems.
Innovation Solution
The development of improved current sensing apparatus with asymmetric geometries and modular designs that allow for flexible placement and reconfiguration around bus bars, optimized for polyphase applications, enabling low-cost manufacturing and enhanced sensitivity while accommodating various physical phenomena and asymmetries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Rogowski coil winding configurations are used, then current sensing accuracy is maintained, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The Rogowski coil is divided into multiple discrete sensing segments or modules, each with simplified winding configurations. These segments can be manufactured separately using standard PCB techniques and then assembled together to form the complete coil assembly, reducing individual manufacturing complexity while maintaining overall sensing accuracy through the combined effect of multiple segments.
Solution Approach 2:
Traditional manual or complex automated winding processes are replaced with PCB-based trace patterns or printed conductor configurations. The sensing coil is implemented as a printed circuit board assembly where conductive traces form the coil windings, eliminating the need for complex mechanical winding operations while preserving the electromagnetic sensing function.
2Ease of operation
If Rogowski coils are made open-ended and flexible for wrapping around conductors, then ease of installation is improved, but manufacturing precision and consistency become more difficult to maintain
Solution Approach 1:
The flexible coil is constructed from multiple rigid or semi-rigid sensing segments that can be individually manufactured with high precision using PCB techniques. These segments are then connected through flexible connectors or articulation points, allowing the overall assembly to bend and wrap around conductors while each individual segment maintains its manufactured geometric precision.
Solution Approach 2:
The coil structure incorporates flexible circuit board materials or thin flexible substrates that allow the sensing elements to bend and conform to different conductor shapes. This flexibility is achieved through the inherent properties of flexible PCB materials while maintaining the precision of the printed conductor patterns through controlled manufacturing processes.
3Speed
If Rogowski coils use air cores instead of magnetically permeable cores, then response to fast-changing currents is improved, but inductance increases
Solution Approach 1:
The coil is divided into multiple smaller sensing segments distributed around the conductor. Each segment contributes a small portion to the total inductance, but the combined effect maintains the fast response characteristics of air-core design while the distributed arrangement optimizes the magnetic coupling with the conductor, effectively managing the inductance level.
4Ease of manufacture
If Rogowski coils are designed for specific applications with fixed geometries, then manufacturing cost is reduced, but adaptability to different applications is lost
Solution Approach 1:
The sensing coil is designed as a modular assembly with standardized segments that can be configured in different arrangements to suit various application requirements. The same basic sensing module can be adapted for different conductor sizes, shapes, and current types by adjusting the number and arrangement of segments, providing universal applicability while maintaining cost-effective manufacturing of standardized components.
Solution Approach 2:
The coil structure incorporates adjustable or reconfigurable elements that allow the geometry and configuration to be modified after manufacturing. This dynamic adaptability enables the same manufactured components to be configured for different applications, combining the cost benefits of standardized production with the flexibility needed for various current sensing scenarios.
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 solution provides low-cost, high-performance current sensing with improved reliability and scalability, capable of handling complex coil configurations and multi-phase systems, offering enhanced sensitivity and resistance to electromagnetic interference.
Implementation Method 1
The voltage that is induced in the coil is proportional to the rate of change of current in the conductor such that the output of the Rogowski coil is indicative to the amount of current passing through the conductor.
Data Source
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AI summary
A low-cost and high-precision current sensing device and methods for use and manufacturing. In one embodiment, the current sensing apparatus comprises a Rogowskt-type coii which is manufactured in segments so as to facilitate the manufacturing process. In an exemplary embodiment, the current sensing apparatus segments are asymmetric in shape and/or composition (e.g., bobbin shape, size, and/or winding configuration) so as to account for asymmetries in the magnetic field distribution around a bus bar, or to accommodate its shape in a more compact form factor, and/or to improve the immunity to the effects of an external magnetic field. Methods of manufacturing and using the aforementioned current sensing apparatus are also disclosed.