Differential Current Sensor Windings for Magnetic Noise Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current detection accuracy is deteriorated by external magnetic fluxes and electromagnetic waves entering a transformer with windings connected in series, leading to noise interference and reduced precision.
Innovation Solution
A current sensor design featuring a pair of windings wound in opposite directions around an annular magnetic core, with return lines extending along the toroidal direction, and a differential amplifier circuit to cancel out external magnetic flux and noise components, improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If windings are connected in series to form a one-turn loop, then the transformer can detect external magnetic fluxes, but current detection accuracy deteriorates due to noise interference
Solution Approach 1:
The winding is divided into multiple winding sections (first winding section, second winding section, etc.) connected in series. Each winding section is equipped with its own damping resistor connected in parallel. This segmentation allows the system to maintain the one-turn loop configuration for external magnetic flux detection while reducing noise interference through distributed damping across sections, thereby improving current detection accuracy.
Solution Approach 2:
Damping resistors are connected in parallel to each winding section to change the electrical parameters of the winding structure. This parameter modification reduces the impact of external magnetic fluxes and electromagnetic waves on the current detection accuracy, allowing the transformer to maintain both external flux detection capability and improved current measurement precision.
2Measurement precision
If damping resistors are connected in parallel to each winding section, then noise interference is reduced, but device complexity increases
Solution Approach 1:
Multiple damping resistors connected in parallel to different winding sections are electrically merged to provide collective noise reduction. This combining approach achieves the noise suppression effect of multiple individual dampers while simplifying the overall structure compared to having completely separate damping circuits for each section, thus reducing device complexity while maintaining measurement precision.
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 enhances current detection accuracy by canceling out external magnetic flux and noise, allowing for precise measurement of currents in higher frequency bands.
Implementation Method 1
a pair of windings including a first winding and a second winding, the first winding and the second winding each including a plurality of winding sections connected in series and wound around different portions of the magnetic core in a poloidal direction along a toroidal direction to detect a current flowing through a measurement target
Implementation Method 2
a plurality of resistance elements, each resistance element is connected in parallel to a respective winding section of the plurality of winding sections
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A current sensor includes an annular magnetic core, a pair of windings each including a plurality of winding sections connected in series and wound around different portions of the magnetic core, and a plurality of resistance elements. Each resistance element is connected in parallel to a respective winding section of the plurality of winding sections. The current sensor includes a return line with one end connected to one end of one winding of the pair of windings and the other end extending from the one end of the one winding to a position near the other end of the one winding along a portion of the magnetic core around which the one winding is wound, and a return line with one end connected to one end of the other winding of the pair of windings and the other end extending from the one end of the other winding to a position near the other end of the other winding along a portion of the magnetic core around which the other winding is wound. The current sensor outputs a signal indicating a difference between an output of the one winding and the return line and an output of the other winding and the return line.