Gradient Detection Current Sensor for Disturbance Rejection
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Solution Overview
Problem
Conventional current sensors face challenges in maintaining detection accuracy due to disturbances from adjacent devices and geomagnetism, which cannot be sufficiently mitigated by existing shielding methods, leading to reduced accuracy and influence from non-target bus bar currents.
Innovation Solution
The current sensor employs two plate-shaped bus bars with gradient detection type magnetic detection elements arranged perpendicular to the bus bars' length direction and tilted with respect to the thickness direction, canceling out uniform disturbances and minimizing the impact of adjacent bus bar magnetic fields by outputting the difference in magnetic field strengths detected at two sensing positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic shield is provided to reduce disturbances, then detection accuracy is improved, but device size and weight increase
Solution Approach 1:
The patent extracts and eliminates the magnetic shield component from the system. Instead of adding shielding elements to block disturbances, the invention uses gradient detection elements that inherently reject uniform magnetic field disturbances through their differential measurement capability, thereby achieving detection accuracy without the size and complexity penalties of physical shields
Solution Approach 2:
The patent replaces the mechanical/physical shielding approach with a sensor-based solution. Rather than using physical barriers to block magnetic fields, the system uses gradient detection elements that electronically compensate for disturbances through their differential measurement and rejection capabilities, substituting physical protection with intelligent sensing
2Object-affected harmful factors
If magnetic detection elements are disposed orthogonal to non-target bus bar magnetic fields, then influence from non-target currents is suppressed, but detection sensitivity to target currents may be reduced
Solution Approach 1:
The patent applies local quality by orienting the gradient detection elements specifically to detect magnetic field gradients in the direction perpendicular to the bus bar length direction. This localized detection orientation allows the system to be sensitive to target current variations while being inherently insensitive to uniform magnetic field disturbances and non-target current influences, achieving both suppression of harmful factors and maintenance of detection sensitivity through spatially-selective sensing
3Measurement precision
If gradient detection type magnetic detection elements are used, then disturbance rejection is improved, but device complexity increases
Solution Approach 1:
The patent merges the disturbance rejection function into the fundamental operation of the magnetic detection elements themselves. By using gradient detection elements that inherently measure field gradients and reject uniform disturbances as part of their basic sensing mechanism, the system combines disturbance rejection with detection functionality, eliminating the need for separate shielding components and reducing overall device complexity
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 detection accuracy by effectively suppressing disturbances and reducing the influence of non-target bus bar currents, while allowing for size reduction and improved sensitivity, with optimal tilt angles minimizing the ratio of disturbance to target current detection differences.
Implementation Method 1
two magnetic detection elements arranged opposite the two bus bars, respectively, in a plate thickness direction of the bus bars to detect a magnetic field strength generated by a current flowing through the corresponding bus bars
Data Source
AI summary
A current sensor includes two bus bars, each of which is formed in a plate shape, the two bus bars being aligned and arranged so as to be spaced apart from each other in a plate width direction thereof, and magnetic detection element arranged opposite the two bus bars, respectively, in a plate thickness direction of the bus bars to detect a magnetic field strength generated by a current flowing through the corresponding bus bars. The magnetic detection element are gradient detection type magnetic detection elements that output a difference between magnetic field strengths detected at two magnetic sensing positions, respectively, and are arranged in such a manner that a detection axis direction thereof is perpendicular to a length direction of the bus bars and is tilted with respect to the plate thickness direction.