Closed-loop Current Transducer with Zero Air Gap Sensor
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Solution Overview
Problem
Current closed-loop current transducers face challenges in reducing manufacturing costs while enhancing performance, accuracy, and reliability, with a need for simpler assembly, increased robustness, and improved sensitivity to external magnetic fields.
Innovation Solution
A closed-loop current transducer design featuring a magnetic circuit core with low magnetic reluctance, a Hall effect sensor, and a compensation coil assembly with a dual coil support bobbin configuration, allowing for efficient magnetic field cancellation and improved measurement range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall effect detectors are positioned in an air-gap of the magnetic circuit to increase sensitivity, then measurement accuracy is improved, but manufacturing precision requirements increase due to the need for accurate controlled dimensioning of the air gap
Solution Approach 1:
The patent eliminates the air gap by positioning the Hall effect sensor directly against the magnetic circuit core, changing the physical parameter of the gap distance from non-zero to zero. This eliminates the need for precise air gap control while maintaining measurement accuracy through direct magnetic field coupling.
2Ease of manufacture
If the compensation coil is wound around a coil support bobbin with flanges, then assembly ease is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent integrates the coil support bobbin directly with the magnetic circuit core structure, merging two separate components into a unified assembly. The bobbin serves dual functions as both structural support for the compensation coil and as part of the magnetic circuit pathway, reducing total component count while maintaining assembly simplicity.
3Adaptability or versatility
If a dual coil support bobbin configuration is used, then measurement range is improved, but manufacturing cost increases
Solution Approach 1:
The patent divides the compensation coil into two separate windings on dual bobbins, with each winding contributing to different aspects of magnetic field cancellation. This segmentation allows the transducer to handle a broader range of current magnitudes and directions, improving measurement versatility while using standard manufacturing processes for each segment.
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 design achieves accurate, reliable, and robust current measurement with reduced sensitivity to external fields, simplified assembly, and a compact form factor, while maintaining a large operating range and stability over time.
Implementation Method 1
a magnetic circuit core made of a material with a low magnetic reluctance to conduct magnetic flux and concentrate a magnetic field
Implementation Method 2
a magnetic field detector... Hall effect detectors are widely used
Implementation Method 3
The compensation coil is configured to generate a magnetic field opposing a magnetic field created by an electrical current to be measured
Data Source
AI summary
A closed-loop current transducer comprising a magnetic circuit core made of a material with a low magnetic reluctance to conduct magnetic flux and concentrate a magnetic field, a magnetic field detector positioned in a magnetic circuit gap of the magnetic circuit core, and a compensation coil assembly comprising a compensation coil and a compensation coil support comprising a coil support bobbin, the compensation coil being wound around the coil support bobbin. The magnetic circuit comprises a first longitudinal branch, a second longitudinal branch, and first and second end branches interconnecting the first and second longitudinal branches such that the branches surround a central opening configured to receive one or more primary conductors therethrough, the magnetic circuit being formed of first and second parts assembled together from opposed ends of the compensation coil support.