Laminated Magnetic Core Structure for High-Current Residual Sensing
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Solution Overview
Problem
Residual current sensors face challenges in accurately measuring very small residual currents due to asymmetrical conductor arrangements and local saturations in magnetic cores, especially when dealing with high primary currents.
Innovation Solution
A magnetic core design featuring two core parts with an irregular comb structure and reduced overlap interfaces, where the longer sheet metal layers contribute less than 40% to the total cross-sectional area, enhances sensitivity and stability, allowing precise measurement of residual currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional magnetic core with uniform sheet metal layers is used, then the structure is simple and easy to manufacture, but local saturations occur in the core due to asymmetrical conductor arrangements, reducing measurement accuracy
Solution Approach 1:
The magnetic core employs sheet metal layers with different lengths (first, second, and third length variants) arranged in specific patterns within core sections. This creates local variations in magnetic path properties that compensate for asymmetrical magnetic field distributions caused by conductor positioning, preventing local saturations and improving residual current measurement accuracy without requiring a completely redesigned core structure
Solution Approach 2:
The magnetic core is divided into multiple core sections, each containing specific patterns of sheet metal layers with different lengths. This segmentation allows independent optimization of magnetic flux distribution in different regions of the core, enabling precise control over magnetic field behavior to eliminate saturations while maintaining overall structural integrity
2Reliability
If the sheet metal layers are made uniform in length, then the manufacturing process is simpler, but the asymmetrical arrangement of primary conductors causes local saturations that reduce sensitivity
Solution Approach 1:
Rather than making all sheet metal layers uniform, the invention introduces local variations in layer lengths (first, second, and third length variants) in specific core sections. This local differentiation stabilizes the magnetic flux distribution under asymmetrical conductor arrangements, preventing saturations and improving sensor reliability while keeping the overall manufacturing process manageable through standardized production techniques
3Strength
If more sheet metal layers overlap at connection points, then the magnetic core has better structural integrity, but the complexity of the comb structure increases and manufacturing becomes more difficult
Solution Approach 1:
The magnetic core is divided into multiple core sections with specific numbers of sheet metal layers each (e.g., first core section with 8 layers, second with 6 layers, third with 4 layers). This segmentation creates a manageable comb structure where layers overlap in a controlled manner at connection points, maintaining structural integrity while enabling practical manufacturing and assembly processes
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 modified magnetic core design significantly improves the accuracy and sensitivity of residual current sensors, enabling effective measurement of small residual currents even in high primary current applications, while minimizing the impact of asymmetrical conductor arrangements and external magnetic fields.
Implementation Method 1
the magnetic field generated by a current to be measured (primary current) flowing through a so-called primary conductor is evaluated and the current actually flowing in the primary conductor is determined from this
Implementation Method 2
Magnetic field sensors (also referred to as magnetic field probes) are primarily inductively-operating sensor types or sensor types based on the Hall effect
Implementation Method 3
In order to focus or conduct the magnetic field, soft magnetic elements (for example, a magnetic core made of soft magnetic material) are used
Data Source
AI summary
A magnetic core for a current sensor is provided. The magnetic core comprises a first and a second core part, each of which is formed from a stack made up of a plurality of sheet metal layers. The second core part has a first end piece structured such that some of the sheet metal layers are longer and protrude beyond the remaining, shorter sheet metal layers. The first core part has a second end piece which is structured inversely to the first end piece of the second core part. The first core part and the second core part are joined together at a connection point such that the longer sheet metal layers of the first end piece and the second end piece overlap at the connection point, wherein the overlap takes place at a number of interfaces that is at least two less than the number of sheet metal layers.