Differential Coil Layout for Interference-Immune Current Sensing
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Solution Overview
Problem
Current sensing devices with coil elements face challenges in accurately measuring current due to interference from non-uniform magnetic and electric fields, which existing configurations fail to adequately address, especially in harsh electrical installations.
Innovation Solution
The configuration of N coil elements arranged in an annular or polygonal pattern with specific electrical connections between winding layers, forming balanced and differential pairs to minimize interference, ensuring strong immunity against external fields and maintaining high measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coil elements are arranged in conventional configurations (successive arrangement with return conductor or intercalated forward-backward paths), then some immunity against uniform magnetic and electric fields is achieved, but strong immunity against non-uniform fields is not provided
Solution Approach 1:
The coil element is divided into multiple winding layers (at least two layers) with each layer contributing to the overall measurement. The segmentation of winding layers allows for differential connections that cancel out interference signals from both uniform and non-uniform magnetic and electric fields, while maintaining sensitivity to the measured current.
Solution Approach 2:
The patent employs differential connections where adjacent winding layers are connected in opposite polarity. This inversion approach causes interference signals induced in adjacent layers to cancel each other out, while the desired measurement signal from the conductor current is summed constructively. This reverse connection strategy provides strong immunity against external fields.
2Ease of manufacture
If multiple winding layers are connected in series without differential pairing, then manufacturing is simplified, but asymmetries and interference loops degrade measurement accuracy
Solution Approach 1:
Adjacent winding layers are connected in differential/opposite polarity configuration. This inversion connection method creates balanced pairs that eliminate asymmetries and interference loops, improving measurement accuracy while maintaining a systematic manufacturing approach that can be automated.
Solution Approach 2:
The patent changes the connection parameter (polarity) between adjacent winding layers from series addition to differential subtraction. This parameter change transforms the electrical characteristics of the coil element, enabling cancellation of interference signals while preserving the measurement signal, thus improving accuracy without significantly complicating manufacturing.
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 effectively eliminates asymmetries and interference loops, providing strong immunity against magnetic and electric interferences, ensuring high accuracy in current measurement even in harsh environments while maintaining low manufacturing costs.
Implementation Method 1
A coil element comprises a bobbin and a winding segment applied on a winding body of the bobbin... to provide a measurement voltage of the device, which is indicative of the current in the conductor
Data Source
AI summary
A current sensing device comprises N coil elements, arranged in annular or polygonal configuration. Coil at =1 is adjacent coil at i=N, and coil at i=x is adjacent to coils at i=x−1 and i=x+1. Each coil comprises a plurality of wire winding layers comprising innermost and outermost wire winding layers that are electrically connected to each other. The outermost layer of coil at i=1 is connected to a terminal via an electrical link. The outermost layer of coil at i=y is connected to innermost layer of coil at i=y−2 via an electrical link. Outermost layer of coil at i=2 is connected to a terminal via an electrical link. Outermost layer of coil at i=z is connected to innermost layer of coil at i=z-2 via an electrical link. Innermost layer of coil at i=N is connected to innermost layer of coil at i=N−1 via an electrical link.