Flexible Magnetic Core Current Sensing for Low-Current Accuracy
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Solution Overview
Problem
Existing contactless current sensors lack flexibility and difficulty in placement around conductors in constrained environments, particularly for measuring low or very low currents and alternating currents at various frequencies.
Innovation Solution
A contactless electric current measuring device with a flexible magnetic core and processing electronics, including a deformable magnetic core formed of several dozen magnetic ribbons, a low-pass or band-stop filter, and a processing unit that uses magnetic polarization to compensate for non-linear magnetization curves, allowing adaptation to constrained environments and accurate measurement of low currents and alternating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigid magnetic core is used in current sensors, then measurement precision is improved, but adaptability to constrained environments deteriorates
Solution Approach 1:
The magnetic core is segmented into multiple thin magnetic ribbons (several dozen layers) stacked together. Each ribbon is thin enough to allow flexibility while maintaining magnetic properties. This segmentation enables the core to bend and adapt to constrained environments while preserving measurement precision through the collective magnetic effect of all layers.
Solution Approach 2:
The patent uses thin magnetic ribbons (few tens of micrometers thickness) as the core structure instead of a solid rigid core. These thin film structures provide inherent flexibility, allowing the sensor to be deformed and placed around conductors in constrained environments while maintaining sufficient magnetic permeability for accurate low current measurements.
2Adaptability or versatility
If a flexible magnetic core is used, then adaptability is improved, but measurement precision deteriorates
Solution Approach 1:
By dividing the magnetic core into multiple thin ribbons, each layer contributes to the overall magnetic flux while the thin structure provides flexibility. The cumulative effect of numerous layers maintains sufficient magnetic permeability for precise measurements even though individual layers are thin and flexible.
Solution Approach 2:
The sensor combines multiple magnetic ribbons into a composite structure that integrates flexibility from thin individual layers with enhanced magnetic properties from the stacked configuration. This composite approach allows the core to be both adaptable to constrained environments and sufficiently magnetic for accurate low current measurement.
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
Enables flexible measurement of low or very low currents and alternating currents at industrial frequencies, overcoming placement challenges and achieving high sensitivity and accuracy by excluding polarization frequency from the measurement signal.
Implementation Method 1
A non-contact electric current measuring device with a flexible magnetic core and processing electronics
Implementation Method 2
a flexible magnetic core and appropriate processing electronics... a deformable magnetic core... which easily adapts to its environment
Data Source
Figure 1~2
Figure 3A~4
Figure 5
AI summary
Non-contact current measurement device comprising a flexible sensor (12) and a processing unit (14), the flexible sensor surrounding a conductor (16) carrying an electric current to be measured and having a deformable magnetic core, device in which the processing unit is configured to, in a measuring coil, add to a measuring current at a frequency F a biasing current at a biasing frequency Fpol not a multiple of this frequency F and then, by means of a filter of determined frequency (144), eliminate this biasing current at the biasing frequency Fpol to retain only the measuring current at the frequency F.