Flexible Bobbin Core Current Sensor for High-Current Measurement
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Solution Overview
Problem
Current current measurement devices in electric power system protection systems have limitations such as a limited dynamic range, core saturation during high-current events, non-linear responses, high cost, and excessive weight due to iron or steel cores, and manufacturing challenges with Rogowski coils.
Innovation Solution
A current measuring device with a hollow, flexible bobbin core wound without a magnetic core, using principles similar to Rogowski coils, which provides accurate signals across a broad range of currents and reduces sensitivity to external influences, facilitating repeatable manufacturing and reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current transformers with iron or steel cores are used, then current measurement capability is provided, but weight becomes excessive and core saturation occurs during high-current events
Solution Approach 1:
The patent removes the magnetic core (iron or steel) from the current transformer design, extracting the problematic heavy component while maintaining the measurement function through air-core or non-magnetic material construction, thereby resolving the contradiction between measurement capability and weight
Solution Approach 2:
The patent changes the physical parameter of the core material from magnetic (iron/steel) to non-magnetic (air or non-magnetic material), which eliminates core saturation during high-current events and significantly reduces weight while preserving current measurement functionality
2Weight of moving object
If Rogowski coils are used, then weight is reduced and manufacturing is simplified, but manufacturing repeatability and sensitivity to external influences become problematic
Solution Approach 1:
The patent employs a flexible bobbin structure that can be molded into precise geometric shapes, providing mechanical stability and consistent geometry for manufacturing repeatability while maintaining the weight advantages of non-rigid constructions, thus resolving the contradiction between weight reduction and manufacturing precision
3Measurement precision
If traditional current transformers are used, then current measurement is provided, but dynamic range is limited and cost increases
Solution Approach 1:
The patent adopts a simplified air-core or non-magnetic core construction with flexible bobbin and standard wire windings, eliminating expensive magnetic materials and complex manufacturing processes, thereby reducing cost while achieving broad dynamic range through the inherent linearity of the design
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 device offers accurate current measurements beyond 300 A, improved mechanical stability, reduced weight, and simplified manufacturing, while maintaining linear responses and robustness against external influences.
Implementation Method 1
a coil having a predetermined number of turns and a predetermined cross-sectional area... the signal generator is configured to generate a calibration signal... by comparing the amplitude of the test signal to the amplitude of the calibration signal
Data Source
AI summary
Current measurement devices for printed circuit board mounting are disclosed herein. The current measurement devices include a hollow and flexible core to improve response to a primary signal and decrease weight. The current measurement device includes a housing with guides to maintain alignment of the core. An electromagnetic shield may be placed between the circumference of the core and the housing. The housing may include apertures to facilitate washing. The current measurement device may include a primary conductor external to the housing.