Supercoil Rogowski Coil Structure for Low-Voltage Interference Reduction
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Solution Overview
Problem
Existing Rogowski coils used for measuring alternating currents in low-voltage applications suffer from significant measurement errors due to inductive and capacitive interference couplings, particularly in small designs, which are difficult to manufacture with complex winding patterns and result in increased sensitivity to external magnetic fields and capacitive couplings.
Innovation Solution
The use of a supercoil configuration comprising at least two identical coils with the same number of winding layers and windings, but differing in orientation, connected in series and arranged on top of each other, with specific connections and grounding of outer winding layers to reduce interference couplings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If Rogowski coils are made very small for compact design in low-voltage applications, then the device size is reduced, but measurement precision deteriorates due to increased sensitivity to external magnetic fields and capacitive couplings
Solution Approach 1:
The Rogowski coil is divided into multiple separate winding layers (first winding layer, second winding layer, third winding layer) with different orientations. Each layer is wound in a specific direction (clockwise or counter-clockwise) to create opposing magnetic field responses, allowing the coil to maintain small size while compensating for external field interference through differential measurement.
Solution Approach 2:
The winding layers are arranged with asymmetric orientations - some windings go clockwise while others go counter-clockwise. This asymmetric configuration creates different capacitive coupling characteristics for each layer, enabling the system to compensate for external magnetic field interference while maintaining compact dimensions.
2Measurement precision
If complex winding patterns are used to reduce sensitivity to external fields, then measurement precision improves, but manufacturing precision deteriorates due to increased manufacturing complexity
Solution Approach 1:
The complex winding pattern is segmented into multiple discrete winding layers, each with a relatively simple winding direction. The first winding layer, second winding layer, and third winding layer can be manufactured separately with standard techniques, then assembled together. This segmentation simplifies individual manufacturing steps while achieving the overall complex functionality through assembly.
Solution Approach 2:
Different regions of the coil have different winding orientations and capacitive coupling characteristics. The first, second, and third winding layers are positioned at different locations and have different winding directions, creating localized variations in electromagnetic properties that collectively provide external field immunity without requiring complex patterns throughout the entire coil.
3Measurement precision
If shielding surfaces are integrated into the Rogowski coil structure to reduce capacitive interference, then measurement precision improves, but device complexity increases
Solution Approach 1:
The shielding function is merged with the measurement function by using the same winding layers that detect current to also serve as capacitive shields. The first, second, and third winding layers are configured to provide both inductive measurement and capacitive shielding simultaneously, eliminating the need for separate shielding components and reducing overall device complexity.
Solution Approach 2:
The winding layers serve multiple functions: they detect the primary current through inductive coupling, provide capacitive shielding against external electric fields, and create opposing magnetic field responses to cancel external field interference. This multi-functionality reduces the need for additional dedicated shielding components.
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 allows for more accurate current measurement with reduced interference, maintaining a compact design suitable for low-voltage applications by minimizing inductive and capacitive interference.
Implementation Method 1
The induced voltage, which is caused by the time-varying magnetic field of the current to be measured, for example the current in a primary conductor
Implementation Method 2
capacitive couplings caused by time-varying electrical fields also play an important role. In general, the conductive winding of the Rogowski coil with all conductive surfaces of the environment forms a more or less complex capacitive structure
Data Source
AI summary
An apparatus for measuring a current in a conductor. The apparatus has at least one first and one second coil and the at least two coils have an identical coil body and have been wound with the same type of wire with the same number of winding layers and the same number of windings. The at least two coils are arranged electrically connected in series and spatially on top of one another. The at least two coils differ in the orientation of their windings such that the at least two coils form a supercoil. The conductor is passed through the supercoil in order to measure the current.