Magnetic Balance Current Sensor Coreless Design
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Solution Overview
Problem
Magnetic balance type current sensors face challenges in miniaturization and workability due to the presence of a magnetic core, leading to increased size and hysteresis, which affects measurement accuracy and power consumption.
Innovation Solution
A magnetic balance type current sensor configuration that includes a magnetic sensor, a magnetic field attenuation unit, and a feedback coil, where the feedback coil generates a cancel magnetic field opposing the induced magnetic field, reducing hysteresis and allowing for miniaturization by integrating components on a substrate without a magnetic core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic core is provided around the conductor to collect magnetic flux, then measurement capability is improved, but device size increases and miniaturization cannot be realized
Solution Approach 1:
The patent extracts and removes the magnetic core from the sensor structure, replacing it with a planar coil configuration. This eliminates the bulky three-dimensional magnetic core while maintaining the magnetic flux collection function through a two-dimensional planar arrangement, thereby achieving miniaturization without sacrificing measurement capability
Solution Approach 2:
The patent transitions from a three-dimensional magnetic core structure to a two-dimensional planar coil structure. By changing the dimensional approach from volumetric to planar, the sensor achieves compact size while maintaining functionality through the strategic arrangement of conductive traces on a substrate
2Measurement precision
If a magnetic core is provided around the conductor, then magnetic flux collection is improved, but workability during installation deteriorates
Solution Approach 1:
The patent replaces the mechanical assembly of a three-dimensional magnetic core around a conductor with a planar integrated structure where the current-carrying conductor and sensing elements are fabricated together on a substrate. This eliminates complex mechanical installation steps and improves workability while maintaining magnetic flux collection through the planar geometry
3Measurement precision
If remanent magnetism is adjusted to improve measurement accuracy, then measurement accuracy is improved, but hysteresis occurs due to the remanent magnetism effect
Solution Approach 1:
The patent removes the magnetic core that causes remanent magnetism, eliminating the source of hysteresis. By replacing the magnetic core with a planar coil structure, the sensor achieves measurement accuracy through geometric design rather than magnetic material properties, thereby avoiding hysteresis while maintaining precision
Solution Approach 2:
The patent changes the fundamental operating parameters from relying on magnetic material properties (remanent magnetism) to relying on geometric and electrical parameters (coil turns, trace geometry, resistance). This parameter transformation eliminates hysteresis while maintaining measurement accuracy through controlled electrical and geometric design
4Productivity
If a magnetic core is provided, then magnetic flux concentration is improved, but the sensor cannot be miniaturized and installation workability deteriorates
Solution Approach 1:
The patent concentrates magnetic flux in the planar dimension rather than using volumetric concentration. The planar coil structure with optimized trace geometry achieves effective magnetic flux collection in two dimensions, eliminating the need for bulky three-dimensional magnetic core structures and enabling sensor miniaturization
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
This configuration enhances measurement accuracy, reduces hysteresis, and improves workability during installation by minimizing magnetic saturation and power consumption, while enabling the sensor to handle larger current values efficiently.
Implementation Method 1
a magnetic sensor of which output varies due to an induced magnetic field from a current wire through which a current to be measured flows
Implementation Method 2
a magnetic field attenuation unit that attenuates the induced magnetic field that acts on the magnetic sensor
Implementation Method 3
a feedback coil which generates a cancel magnetic field that cancels the induced magnetic field in accordance with the output of the magnetic sensor
Data Source
AI summary
A magnetic balance type current sensor includes: a magnetic detection bridge circuit of which output varies due to an induced magnetic field from a current wire; a magnetic field attenuation unit that attenuates the induced magnetic field that acts on a magnetoresistive effect element; and a feedback coil which generates a cancel magnetic field that cancels the induced magnetic field in accordance with the output of the magnetic detection bridge circuit, and through which a current corresponding to the current to be measured flows when it enters a balanced state in which the cancel magnetic field and the induced magnetic field cancel each other, wherein the feedback coil is provided in such a manner that a direction of the cancel magnetic field that acts on the magnetic field attenuation unit is opposite to a direction of the induced magnetic field that acts on the magnetic field attenuation unit.